Science.gov

Sample records for simulated dissolver off-gas

  1. Off-gas Adsorption Model and Simulation - OSPREY

    SciTech Connect

    Veronica J Rutledge

    2013-10-01

    The absence of industrial scale nuclear fuel reprocessing in the U.S. has precluded the necessary driver for developing the advanced simulation capability now prevalent in so many other countries. Thus, it is essential to model complex series of unit operations to simulate, understand, and predict inherent transient behavior. A capability of accurately simulating the dynamic behavior of advanced fuel cycle separation processes is expected to provide substantial cost savings and many technical benefits. To support this capability, a modeling effort focused on the off-gas treatment system of a used nuclear fuel recycling facility is in progress. The off-gas separation consists of a series of scrubbers and adsorption beds to capture constituents of interest. Dynamic models are being developed to simulate each unit operation involved so each unit operation can be used as a stand-alone model and in series with multiple others. Currently, an adsorption model has been developed within Multi-physics Object Oriented Simulation Environment (MOOSE) developed at the Idaho National Laboratory (INL). Off-gas Separation and REcoverY (OSPREY) models the adsorption of offgas constituents for dispersed plug flow in a packed bed under non-isothermal and non-isobaric conditions. Inputs to the model include gas composition, sorbent and column properties, equilibrium and kinetic data, and inlet conditions. The simulation outputs component concentrations along the column length as a function of time from which breakthrough data can be obtained. The breakthrough data can be used to determine bed capacity, which in turn can be used to size columns. In addition to concentration data, the model predicts temperature along the column length as a function of time and pressure drop along the column length. A description of the OSPREY model, results from krypton adsorption modeling and plans for modeling the behavior of iodine, xenon, and tritium will be discussed.

  2. Off-gas adsorption model and simulation - OSPREY

    SciTech Connect

    Rutledge, V.J.

    2013-07-01

    A capability of accurately simulating the dynamic behavior of advanced fuel cycle separation processes is expected to provide substantial cost savings and many technical benefits. To support this capability, a modeling effort focused on the off-gas treatment system of a used nuclear fuel recycling facility is in progress. The off-gas separation consists of a series of scrubbers and adsorption beds to capture constituents of interest. Dynamic models are being developed to simulate each unit operation involved so each unit operation can be used as a stand-alone model and in series with multiple others. Currently, an adsorption model has been developed within Multi-physics Object Oriented Simulation Environment (MOOSE) developed at the Idaho National Laboratory (INL). Off-gas Separation and Recovery (OSPREY) models the adsorption of offgas constituents for dispersed plug flow in a packed bed under non-isothermal and non-isobaric conditions. Inputs to the model include gas composition, sorbent and column properties, equilibrium and kinetic data, and inlet conditions. The simulation outputs component concentrations along the column length as a function of time from which breakthrough data can be obtained. The breakthrough data can be used to determine bed capacity, which in turn can be used to size columns. In addition to concentration data, the model predicts temperature along the column length as a function of time and pressure drop along the column length. A description of the OSPREY model, results from krypton adsorption modeling and plans for modeling the behavior of iodine, xenon, and tritium will be discussed. (author)

  3. Dissolver Off-gas Hot Operations Authorization (AFCI CETE Milestone Report)

    SciTech Connect

    Jubin, Robert Thomas

    2009-06-01

    The head-end processing of the Coupled-End-to-End (CETE) Demonstration includes fuel receipt, fuel disassembly, exposure of fuel (e.g., by segmenting the fuel pins), voloxidation of the fuel to separate tritium, and fuel dissolution. All of these processing steps with the exception of the dissolution step will be accomplished in the Irradiated Fuels Examination Laboratory (IFEL) (Building 3525). The final headend step will be performed in the Radiochemical Engineering Development Center (Building 7920). The primary purpose of the fuel dissolution step is to prepare the solid fuel for subsequent liquid separations steps. This is accomplished by dissolving the fuel solids using nitric acid. During the dissolution process gases are evolved. Oxides of nitrogen are the primary off-gas components generated by the reactions of nitric acid and the fuel oxides however, during the dissolution and sparging of the resulting solution, iodine, C-14 as carbon dioxide, xenon, and krypton gasses are also released to the off-gas stream. The Dissolver Off-gas treatment rack provides a means of trapping these volatile fission products and other gases via various trapping media. Specifically the rack will recover iodine on a solid sorbent bed, scrub NOx in a water/acid column, scrub CO{sub 2} in a caustic scrubber column, remove moisture with solid sorbent drier beds and recover Xe and Kr using solid absorbent beds. The primary purpose of this experimental rack and the off-gas rack associated with the voloxidation equipment located at IFEL is to close the material balances around the volatile gases and to provide an understanding of the impacts of specific processing conditions on the fractions of the volatile components released from the various head-end processing steps.

  4. Design, Fabrication, and Shakeout Testing of ATALANTE Dissolver Off-Gas Sorbent-Based Capture System

    SciTech Connect

    Walker, Jr, Joseph Franklin; Jubin, Robert Thomas; Jordan, Jacob A.; Bruffey, Stephanie H.

    2015-07-31

    A sorbent-based capture system designed for integration into the existing dissolver off-gas (DOG) treatment system at the ATelier Alpha et Laboratoires pour ANalyses, Transuraniens et Etudes de retraitement (ATALANTE) facility has been successfully designed and fabricated and has undergone shakeout testing. Discussions with personnel from the ATALANTE facility provided guidance that was used for the design. All components for this system were specified, procured, and received on site at Oak Ridge National Laboratory (ORNL). The system was then fabricated and tested at ORNL to verify operation. Shakeout testing resulted in a simplified system. This system should be easily installed into the existing facility and should be straightforward to operate during future experimental testing. All parts were selected to be compatible with ATALANTE power supplies, space requirements, and the existing DOG treatment system. Additionally, the system was demonstrated to meet all of four design requirements. These include (1) a dissolver off-gas flow rate of ≤100 L/h (1.67 L/min), (2) an external temperature of ≤50°C for all system components placed in the hot cell, (3) a sorbent bed temperature of ~150°C, and (4) a gas temperature of ~150°C upon entry into the sorbent bed. The system will be ready for shipment and installation in the existing DOG treatment system at ATALANTE in FY 2016.

  5. Regulatory off-gas analysis from the evaporation of Hanford simulated waste spiked with organic compounds.

    PubMed

    Saito, Hiroshi H; Calloway, T Bond; Ferrara, Daro M; Choi, Alexander S; White, Thomas L; Gibson, Luther V; Burdette, Mark A

    2004-10-01

    After strontium/transuranics removal by precipitation followed by cesium/technetium removal by ion exchange, the remaining low-activity waste in the Hanford River Protection Project Waste Treatment Plant is to be concentrated by evaporation before being mixed with glass formers and vitrified. To provide a technical basis to permit the waste treatment facility, a relatively organic-rich Hanford Tank 241-AN-107 waste simulant was spiked with 14 target volatile, semi-volatile, and pesticide compounds and evaporated under vacuum in a bench-scale natural circulation evaporator fitted with an industrial stack off-gas sampler at the Savannah River National Laboratory. An evaporator material balance for the target organics was calculated by combining liquid stream mass and analytical data with off-gas emissions estimates obtained using U.S. Environmental Protection Agency (EPA) SW-846 Methods. Volatile and light semi-volatile organic compounds (<220 degrees C BP, >1 mm Hg vapor pressure) in the waste simulant were found to largely exit through the condenser vent, while heavier semi-volatiles and pesticides generally remain in the evaporator concentrate. An OLI Environmental Simulation Program (licensed by OLI Systems, Inc.) evaporator model successfully predicted operating conditions and the experimental distribution of the fed target organics exiting in the concentrate, condensate, and off-gas streams, with the exception of a few semi-volatile and pesticide compounds. Comparison with Henry's Law predictions suggests the OLI Environmental Simulation Program model is constrained by available literature data. PMID:15540577

  6. Regulatory Off-Gas Analysis from the Evaporation of Hanford Simulated Waste Spiked with Organic Compounds

    SciTech Connect

    Saito, H.H.

    2001-03-28

    The purposes of this work were to: (1) develop preliminary operating data such as expected concentration endpoints for flow sheet development and evaporator design, and (2) examine the regulatory off-gas emission impacts from the evaporation of relatively organic-rich Hanford Tank 241-AN-107 Envelope C waste simulant containing 14 volatile, semi-volatile and pesticide organic compounds potentially present in actual Hanford RPP waste.

  7. Regulatory Off-Gas Analysis from the Evaporation of Hanford Simulated Waste Spiked with Organic Compounds

    SciTech Connect

    Calloway, T.B. Jr.

    2003-10-23

    After strontium/transuranics removal by precipitation followed by cesium/technetium removal by ion exchange, remaining low activity waste in the Hanford River Protection Project Waste Treatment Plant is to be concentrated by evaporation prior to being mixed with glass formers and vitrified. To provide a technical basis to permit the waste treatment facility, a relatively organic-rich Hanford Tank 241-AN-107 waste simulant was spiked with 14 target volatile, semi-volatile and pesticide compounds, and evaporated under vacuum in a bench-scale natural circulation evaporator fitted with an industrial stack off-gas sampler at the Savannah River Technology Center. An evaporator material balance for the target organics was calculated by combining liquid stream mass and analytical data with off-gas emissions estimates obtained using EPA SW-846 Methods. Volatile and light semi-volatile organic compounds in the waste simulant were found to largely exit through the condenser vent, while heavier semi-volatiles and pesticides generally remain in the evaporator concentrate. An OLI Environmental Simulation Program evaporator model successfully predicted operating conditions and the experimental distribution of the fed target organics exiting in the concentrate, condensate and off-gas streams with the exception of a few semi-volatile and pesticide compounds. Comparison with Henry's Law predictions suggests the OLI ESP model is constrained by available literature data.

  8. Laboratory Evaporation Testing Of Hanford Waste Treatment Plant Low Activity Waste Off-Gas Condensate Simulant

    SciTech Connect

    Adamson, Duane J.; Nash, Charles A.; McCabe, Daniel J.; Crawford, Charles L.; Wilmarth, William R.

    2014-01-27

    (chloride, fluoride, sulfur), will have high ammonia, and will contain carryover particulates of glass-former chemicals. These species have potential to cause corrosion of tanks and equipment, precipitation of solids, release of ammonia gas vapors, and scale in the tank farm evaporator. Routing this stream to the tank farms does not permanently divert it from recycling into the WTP, only temporarily stores it prior to reprocessing. Testing is normally performed to demonstrate acceptable conditions and limits for these compounds in wastes sent to the tank farms. The primary parameter of this phase of the test program was measuring the formation of solids during evaporation in order to assess the compatibility of the stream with the evaporator and transfer and storage equipment. The origin of this LAW Off-Gas Condensate stream will be the liquids from the Submerged Bed Scrubber (SBS) and the Wet Electrostatic Precipitator (WESP) from the LAW facility melter offgas system. The stream is expected to be a dilute salt solution with near neutral pH, and will likely contain some insoluble solids from melter carryover. The soluble components are expected to be mostly sodium and ammonium salts of nitrate, chloride, and fluoride. This stream has not been generated yet, and, thus, the composition will not be available until the WTP begins operation, but a simulant has been produced based on models, calculations, and comparison with pilot-scale tests. This report discusses results of evaporation testing of the simulant. Two conditions were tested, one with the simulant at near neutral pH, and a second at alkaline pH. The neutral pH test is comparable to the conditions in the Hanford Effluent Treatment Facility (ETF) evaporator, although that evaporator operates at near atmospheric pressure and tests were done under vacuum. For the alkaline test, the target pH was based on the tank farm corrosion control program requirements, and the test protocol and equipment was comparable to that

  9. Cracking of simulated oil refinery off-gas over a coal char, petroleum coke, and quartz

    SciTech Connect

    Yuan Zhang; Jin-hu Wu; Dong-ke Zhang

    2008-03-15

    The cracking of oil refinery off-gas, simulated with a gas mixture containing methane (51%), ethylene (21.4%), ethane (21.1%), and propane (6.5%), over a coal char, petroleum coke, and quartz, respectively, has been studied in a fixed bed reactor. The experiments were performed at temperatures between 850 and 1000{sup o}C and at atmospheric pressure. The results show that the conversions of all species considered increased with increasing temperature. Ethane and propane completely decomposed over all three bed materials in the temperature range investigated. However, the higher initial conversion rates of methane and ethylene cracking at all temperatures were observed only over the coal char and not on the petroleum coke and quartz, indicating a significant catalytic effect of the coal char on methane and ethylene cracking. Methane and ethylene conversions decreased with reaction time due to deactivation of the coal char by carbon deposition on the char surface and, in the later stage of a cracking experiment, became negative, suggesting that methane and ethylene had been formed during the cracking of ethane and propane. 16 refs., 13 figs., 2 tabs.

  10. LABORATORY OPTIMIZATION TESTS OF TECHNETIUM DECONTAMINATION OF HANFORD WASTE TREATMENT PLANT LOW ACTIVITY WASTE OFF-GAS CONDENSATE SIMULANT

    SciTech Connect

    Taylor-Pashow, K.; Nash, C.; McCabe, D.

    2014-09-29

    compatible with longterm tank storage and immobilization methods. For this new application, testing is needed to demonstrate acceptable treatment sorbents and precipitating agents and measure decontamination factors for additional radionuclides in this unique waste stream. The origin of this LAW Off-Gas Condensate stream will be the liquids from the Submerged Bed Scrubber (SBS) and the Wet Electrostatic Precipitator (WESP) from the LAW melter off-gas system. The stream is expected to be a dilute salt solution with near neutral pH, and will likely contain some insoluble solids from melter carryover. The soluble components are expected to be mostly sodium and ammonium salts of nitrate, chloride, and fluoride. This stream has not been generated yet and will not be available until the WTP begins operation, but a simulant has been produced based on models, calculations, and comparison with pilot-scale tests. One of the radionuclides that is volatile and expected to be in greatest abundance in this LAW Off-Gas Condensate stream is Technetium-99 ({sup 99}Tc). Technetium will not be removed from the aqueous waste in the Hanford WTP, and will primarily end up immobilized in the LAW glass by repeated recycle of the off-gas condensate into the LAW melter. Other radionuclides that are low but are also expected to be in measurable concentration in the LAW Off-Gas Condensate are {sup 129}I, {sup 90}Sr, {sup 137}Cs, {sup 241}Pu, and {sup 241}Am. These are present due to their partial volatility and some entrainment in the off-gas system. This report discusses results of optimized {sup 99}Tc decontamination testing of the simulant. Testing examined use of inorganic reducing agents for {sup 99}Tc. Testing focused on minimizing the quantity of sorbents/reactants added, and minimizing mixing time to reach the decontamination targets in this simulant formulation. Stannous chloride and ferrous sulfate were tested as reducing agents to determine the minimum needed to convert soluble pertechnetate

  11. Laboratory Scoping Tests Of Decontamination Of Hanford Waste Treatment Plant Low Activity Waste Off-Gas Condensate Simulant

    SciTech Connect

    Taylor-Pashow, Kathryn M.; Nash, Charles A.; Crawford, Charles L.; McCabe, Daniel J.; Wilmarth, William R.

    2014-01-21

    compatible with longterm tank storage and immobilization methods. For this new application, testing is needed to demonstrate acceptable treatment sorbents and precipitating agents and measure decontamination factors for additional radionuclides in this unique waste stream. The origin of this LAW Off-Gas Condensate stream will be the liquids from the Submerged Bed Scrubber (SBS) and the Wet Electrostatic Precipitator (WESP) from the LAW melter off-gas system. The stream is expected to be a dilute salt solution with near neutral pH, and will likely contain some insoluble solids from melter carryover. The soluble components are expected to be mostly sodium and ammonium salts of nitrate, chloride, and fluoride. This stream has not been generated yet and will not be available until the WTP begins operation, but a simulant has been produced based on models, calculations, and comparison with pilot-scale tests. One of the radionuclides that is volatile and expected to be in high concentration in this LAW Off-Gas Condensate stream is Technetium-99 ({sup 99}Tc). Technetium will not be removed from the aqueous waste in the Hanford WTP, and will primarily end up immobilized in the LAW glass by repeated recycle of the off-gas condensate into the LAW melter. Other radionuclides that are also expected to be in appreciable concentration in the LAW Off-Gas Condensate are {sup 129}I, {sup 90}Sr, {sup 137}Cs, and {sup 241}Am. This report discusses results of preliminary radionuclide decontamination testing of the simulant. Testing examined use of Monosodium Titanate (MST) to remove {sup 90}Sr and actinides, inorganic reducing agents for {sup 99}Tc, and zeolites for {sup 137}Cs. Test results indicate that excellent removal of {sup 99}Tc was achieved using Sn(II)Cl{sub 2} as a reductant, coupled with sorption onto hydroxyapatite, even in the presence of air and at room temperature. This process was very effective at neutral pH, with a Decontamination Factor (DF) >577 in two hours. It was less

  12. Steady-state and dynamic simulation study on boil-off gas minimization and recovery strategies at LNG exporting terminals

    NASA Astrophysics Data System (ADS)

    Kurle, Yogesh

    Liquefied natural gas (LNG) is becoming one of the prominent clean energy sources with its abundance, high calorific value, low emission, and price. Vapors generated from LNG due to heat leak are called boil-off gas (BOG). As world-wide LNG productions are increasing fast, BOG generation and handling problems are becoming more critical. Also, due to stringent environmental regulations, flaring of BOG is not a viable option. In this study, typical Propane-and-Mixed-Refrigerant (C3-MR) process, storage facilities, and loading facilities are modeled and simulated to study BOG generation at LNG exporting terminals, including LNG processing, storage, and berth loading areas. Factors causing BOG are presented, and quantities of BOG generated due to each factor at each location are calculated under different LNG temperatures. Various strategies to minimize, recover, and reuse BOG are also studied for their feasibility and energy requirements. Rate of BOG generation during LNG loading---Jetty BOG (JBOG)---changes significantly with loading time. In this study, LNG vessel loading is simulated using dynamic process simulation software to obtain JBOG generation profile and to study JBOG recovery strategies. Also, fuel requirements for LNG plant to run steam-turbine driven compressors and gas-turbine driven compressors are calculated. Handling of JBOG generated from multiple loadings is also considered. The study would help proper handling of BOG problems in terms of minimizing flaring at LNG exporting terminals, and thus reducing waste, saving energy, and protecting surrounding environments.

  13. Surface Decontamination of Simulated Chemical Warfare Agents Using a Nonequilibrium Plasma with Off-Gas Monitoring

    SciTech Connect

    Moeller, Trevor M.; Alexander, M. Lizabeth; Engelhard, Mark H.; Gaspar, Dan J.; Luna, Maria L.; Irving, Patricia M.

    2002-08-01

    InnovaTek is developing a surface decontamination technology that utilizes active species generated in a nonequilibrium corona plasma. The plasma technology was tested against DMMP, a simulant for the chemical agent Sarin. GC-MS analysis showed that a greater than four log10 destruction of the DMMP on an aluminum surface was achieved in a 10 minute treatment. An ion-trap mass spectrometer was utilized to collect time-resolved data on the treatment off-gases. These data indicate that only non-toxic fragments of the broken down DMMP molecule were present in the gas phase. The technology is being further refined to develop a product that will not only decontaminate surfaces but will also sense when decontamination is complete

  14. Laboratory optimization tests of technetium decontamination of Hanford Waste Treatment Plant low activity waste melter off-gas condensate simulant

    SciTech Connect

    Taylor-Pashow, Kathryn M.L.; McCabe, Daniel J.

    2015-11-01

    The Hanford Waste Treatment and Immobilization Plant (WTP) Low Activity Waste (LAW) vitrification facility will generate an aqueous condensate recycle stream (LAW Off-Gas Condensate) from the off-gas system. The baseline plan for disposition of this stream is to send it to the WTP Pretreatment Facility, where it will be blended with LAW, concentrated by evaporation and recycled to the LAW vitrification facility again. Alternate disposition of this stream would eliminate recycling of problematic components, and would enable simplified operation of the LAW melter and the Pretreatment Facilities. Eliminating this stream from recycling within WTP would also decrease the LAW vitrification mission duration and quantity of glass waste.

  15. Emissions characterization and off-gas system development for processing simulated mixed waste in a plasma centrifugal furnace

    SciTech Connect

    Filius, K.D.; Whitworth, C.G.

    1996-12-31

    Plasma arc technology is a high temperature process that completely oxidizes organic waste fractions: inorganic hazardous and radionuclide waste fractions are oxidized and encapsulated in a highly durable slag. The robust nature of the technology lends itself to application of diverse mixed and hazardous wastestreams. Over 500 hours of testing have been completed at the Department of Energy`s Western Environmental Technology Office with a pilot-scale system. This testing was designed to demonstrate operability over a wide range of wastes and provide the data required to evaluate potential applications of the technology on both a technical and economic basis. In addition to characterization of the off gas for typical combustion products, the fate of radionuclide surrogates and hazardous elements within the Plasma Arc Centrifugal Treatment (PACT) system has been investigated extensively. Test results to date demonstrate that cerium, a plutonium surrogate, remains almost exclusively in the slag matrix. Hazardous elements such as chromium and lead volatilize to a greater extent and are captured by the off-gas system. Preliminary design work is underway to develop a minimum emissions off-gas system for demonstration on a engineering-scale plasma unit. The proposed system will filter particulate matter from the hot gas stream and treat them in an electric ceramic oxidizer, which replaces the conventional afterburner, prior to quenching and acid gas removal. 5 refs., 3 figs., 5 tabs.

  16. Simulation of a continuous rotary dissolver

    SciTech Connect

    Carnal, C.L.; Hardy, J.E.; Lewis, B.E.

    1989-01-01

    This paper describes the simulation of a rotating, multistage chemical reactor that dissolves spent nuclear fuel for reprocessing in a breeder cycle. The continuous, time-dependent process model of a dissolver was developed using the Advanced Continuous Simulation Language (ACSL) to calculate various temperatures and the masses of the chemical constituents of the solution in each stage. The Gear integration algorithm (Gear 1971) was used to accommodate the stiff dynamics. An arrangement of interacting discrete sections was employed to cause fresh fuel to be added and dissolver rotations to occur at appropriate times. By changing various constants, the model can simulate the effect of different fuel compositions and operational scenarios. The model code is a valuable tool for analysis of the performance of the dissolution system and has been instrumental in its design. 5 refs., 7 figs.

  17. Adsorption Model for Off-Gas Separation

    SciTech Connect

    Veronica J. Rutledge

    2011-03-01

    The absence of industrial scale nuclear fuel reprocessing in the U.S. has precluded the necessary driver for developing the advanced simulation capability now prevalent in so many other countries. Thus, it is essential to model complex series of unit operations to simulate, understand, and predict inherent transient behavior and feedback loops. A capability of accurately simulating the dynamic behavior of advanced fuel cycle separation processes will provide substantial cost savings and many technical benefits. The specific fuel cycle separation process discussed in this report is the off-gas treatment system. The off-gas separation consists of a series of scrubbers and adsorption beds to capture constituents of interest. Dynamic models are being developed to simulate each unit operation involved so each unit operation can be used as a stand-alone model and in series with multiple others. Currently, an adsorption model has been developed in gPROMS software. Inputs include gas stream constituents, sorbent, and column properties, equilibrium and kinetic data, and inlet conditions. It models dispersed plug flow in a packed bed under non-isothermal and non-isobaric conditions for a multiple component gas stream. The simulation outputs component concentrations along the column length as a function of time from which the breakthrough data is obtained. It also outputs temperature along the column length as a function of time and pressure drop along the column length. Experimental data will be input into the adsorption model to develop a model specific for iodine adsorption on silver mordenite as well as model(s) specific for krypton and xenon adsorption. The model will be validated with experimental breakthrough curves. Another future off-gas modeling goal is to develop a model for the unit operation absorption. The off-gas models will be made available via the server or web for evaluation by customers.

  18. Laboratory Optimization Tests of Technetium Decontamination of Hanford Waste Treatment Plant Direct Feed Low Activity Waste Melter Off-Gas Condensate Simulant

    SciTech Connect

    Taylor-Pashow, K.; McCabe, D.

    2015-12-23

    The Hanford Waste Treatment and Immobilization Plant (WTP) Low Activity Waste (LAW) vitrification facility will generate an aqueous condensate recycle stream (LAW Off-Gas Condensate) from the off-gas system. The baseline plan for disposition of this stream is to send it to the WTP Pretreatment Facility, where it will be blended with LAW, concentrated by evaporation and recycled to the LAW vitrification facility. Alternate disposition of this stream would eliminate recycling of problematic components, and would enable less integrated operation of the LAW melter and the Pretreatment Facilities. Eliminating this stream from recycling within WTP would also decrease the LAW vitrification mission duration and quantity of glass waste.

  19. FINAL REPORT REGULATORY OFF GAS EMISSIONS TESTING ON THE DM1200 MELTER SYSTEM USING HLW AND LAW SIMULANTS VSL-05R5830-1 REV 0 10/31/05

    SciTech Connect

    KRUGER AA; MATLACK KS; GONG W; BARDAKCI T; D'ANGELO NA; BRANDYS M; KOT WK; PEGG IL

    2011-12-29

    system was reconfigured to enable testing of the baseline HLW or LAW off-gas trains to perform off-gas emissions testing with both LAW and HLW simulants in the present work. During 2002 and 2003, many of these off-gas components were tested individually and in an integrated manner with the DM1200 Pilot Melter. Data from these tests are being used to support engineering design confirmation and to provide data to support air permitting activities. In fiscal year 2004, the WTP Project was directed by the Office of River Protection (ORP) to comply with Environmental Protection Agency (EPA) Maximum Achievable Control Technology (MACT) requirements for organics. This requires that the combined melter and off-gas system have destruction and removal efficiency (DRE) of >99.99% for principal organic dangerous constituents (PODCs). In order to provide confidence that the melter and off-gas system are able to achieve the required DRE, testing has been directed with both LAW and HLW feeds. The tests included both 'normal' and 'challenge' WTP melter conditions in order to obtain data for the potential range of operating conditions for the WTP melters and off-gas components. The WTP Project, Washington State Department of Ecology, and ORP have agreed that naphthalene will be used for testing to represent semi-volatile organics and allyl alcohol will be used to represent volatile organics. Testing was also performed to determine emissions of halides, metals, products of incomplete combustion (PICs), dioxins, furans, coplanar PCBs, total hydrocarbons, and COX and NOX, as well as the particle size distribution (PSD) of particulate matter discharged at the end of the off-gas train. A description of the melter test requirements and analytical methods used is provided in the Test Plan for this work. Test Exceptions were subsequently issued which changed the TCO catalyst, added total organic emissions (TOE) to exhaust sampling schedule, and allowing modification of the test conditions in

  20. Methods of Off-Gas Flammability Control for DWPF Melter Off-Gas System at Savannah River Site

    SciTech Connect

    Choi, A.S.; Iverson, D.C.

    1996-05-02

    Several key operating variables affecting off-gas flammability in a slurry-fed radioactive waste glass melter are discussed, and the methods used to prevent potential off-gas flammability are presented. Two models have played a central role in developing such methods. The first model attempts to describe the chemical events occurring during the calcining and melting steps using a multistage thermodynamic equilibrium approach, and it calculates the compositions of glass and calcine gases. Volatile feed components and calcine gases are fed to the second model which then predicts the process dynamics of the entire melter off-gas system including off-gas flammability under both steady state and various transient operating conditions. Results of recent simulation runs are also compared with available data

  1. Off gas film cooler cleaner

    SciTech Connect

    Dhingra, H.S.; Koch, W.C.; Burns, D.C.

    1995-12-31

    An apparatus is described for cleaning depositions of particulate matter from the inside of tubular piping while the piping is in use. The apparatus is remotely controlled in order to operate in hazardous environments. A housing containing brush and shaft assemblies is mounted on top of the tubular piping. Pneumatic cylinders provide linear motion. A roller nut bearing provides rotary motion. The combined motion causes the brush assembly to rotate as it travels along the tube dislodging particulate matter. The main application for this invention is to clean the off gas cooler of a radioactive waste vitrification unit.

  2. Glass melter off-gas system

    DOEpatents

    Jantzen, Carol M.

    1997-01-01

    Apparatus and method for melting glass in a glass melter in such a way as to reduce deposition of particulates in the off-gas duct. Deposit accumulation is reduced by achieving an off-gas velocity above approximately 15 meters/second and an off-gas temperature as close as possible to, but not higher than, the glass softening point. Because the deposits are largely water-soluble, those that do form on the interior surface of the duct can be readily removed by injecting water or steam directly into the off-gas duct from its entrance or exit.

  3. Method for treating a nuclear process off-gas stream

    DOEpatents

    Pence, Dallas T.; Chou, Chun-Chao

    1984-01-01

    Disclosed is a method for selectively removing and recovering the noble gas and other gaseous components typically emitted during nuclear process operations. The method is adaptable and useful for treating dissolver off-gas effluents released during reprocessing of spent nuclear fuels whereby to permit radioactive contaminant recovery prior to releasing the remaining off-gases to the atmosphere. Briefly, the method sequentially comprises treating the off-gas stream to preliminarily remove NO.sub.x, hydrogen and carbon-containing organic compounds, and semivolatile fission product metal oxide components therefrom; adsorbing iodine components on silver-exchanged mordenite; removing water vapor carried by said stream by means of a molecular sieve; selectively removing the carbon dioxide components of said off-gas stream by means of a molecular sieve; selectively removing xenon in gas phase by passing said stream through a molecular sieve comprising silver-exchanged mordenite; selectively separating krypton from oxygen by means of a molecular sieve comprising silver-exchanged mordenite; selectively separating krypton from the bulk nitrogen stream using a molecular sieve comprising silver-exchanged mordenite cooled to about -140.degree. to -160.degree. C.; concentrating the desorbed krypton upon a molecular sieve comprising silver-exchange mordenite cooled to about -140.degree. to -160.degree. C.; and further cryogenically concentrating, and the recovering for storage, the desorbed krypton.

  4. Dynamic Absorption Model for Off-Gas Separation

    SciTech Connect

    Veronica J. Rutledge

    2011-07-01

    Modeling and simulations will aid in the future design of U.S. advanced reprocessing plants for the recovery and recycle of actinides in used nuclear fuel. The specific fuel cycle separation process discussed in this report is the off-gas treatment system. The off-gas separation consists of a series of scrubbers and adsorption beds to capture constituents of interest. Dynamic models are being developed to simulate each unit operation involved so each unit operation can be used as a stand-alone model and in series with multiple others. Currently, a rate based, dynamic absorption model is being developed in gPROMS software. Inputs include liquid and gas stream constituents, column properties, liquid and gas phase reactions, number of stages, and inlet conditions. It simulates multiple component absorption with countercurrent flow and accounts for absorption by mass transfer and chemical reaction. The assumption of each stage being a discrete well-mixed entity was made. Therefore, the model is solved stagewise. The simulation outputs component concentrations in both phases as a function of time from which the rate of absorption is determined. Temperature of both phases is output as a function of time also. The model will be used able to be used as a standalone model in addition to in series with other off-gas separation unit operations. The current model is being generated based on NOx absorption; however, a future goal is to develop a CO2 specific model. The model will have the capability to be modified for additional absorption systems. The off-gas models, both adsorption and absorption, will be made available via the server or web for evaluation by customers.

  5. MATHEMATICAL SIMULATION TOOLS FOR DEVELOPING DISSOLVED OXYGEN TMDLS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This paper presents an extended abstract of a research paper describing four commonly used dissolved oxygen (DO) simulation models. The concentration of DO in surface waters is one of the most commonly used indicators of river and stream health. Regulators and other professionals are increasingly r...

  6. Treatment of nitrous off-gas from dissolution of sludges

    SciTech Connect

    Flament, T.A.

    1998-08-25

    Several configurations have been reviewed for the NO{sub x} removal of dissolver off-gas. A predesign has been performed and operating conditions have been optimized. Simple absorption columns seems to be sufficient. NHC is in charge of the treatment of sludges containing mainly uranium dioxide and metallic uranium. The process is based on the following processing steps a dissolution step to oxidize the pyrophoric materials and to dissolve radionuclides (uranium, plutonium, americium and fission products), a solid/liquid separation to get rid of the insoluble solids (to be disposed at ERDF), an adjustment of the acid liquor with neutronic poisons, and neutralization of the acid liquor with caustic soda. The dissolution step generates a flow of nitrous fumes which was evaluated in a previous study. This NO{sub x} flow has to be treated. The purpose of this report is to study the treatment process of the nitrous vapors and to 0482 perform a preliminary design. Several treatment configurations are studied and the most effective process option with respect to the authorized level of discharge into atmosphere is discussed. As a conclusion, recommendations concerning the unit preliminary design are given.

  7. Simulation of hydrodynamics, temperature, and dissolved oxygen in Bull Shoals Lake, Arkansas, 1994-1995

    USGS Publications Warehouse

    Galloway, Joel M.; Green, W. Reed

    2003-01-01

    and dissolved-oxygen concentration through time. However, results from both scenarios for water temperature and dissolved-oxygen concentration were within the boundaries of the error between measured and simulated water column profile values.

  8. Method and apparatus for off-gas composition sensing

    DOEpatents

    Ottesen, David Keith; Allendorf, Sarah Williams; Hubbard, Gary Lee; Rosenberg, David Ezechiel

    1999-01-01

    An apparatus and method for non-intrusive collection of off-gas data in a steelmaking furnace includes structure and steps for transmitting a laser beam through the off-gas produced by a steelmaking furnace, for controlling the transmitting to repeatedly scan the laser beam through a plurality of wavelengths in its tuning range, and for detecting the laser beam transmitted through the off-gas and converting the detected laser beam to an electrical signal. The electrical signal is processed to determine characteristics of the off-gas that are used to analyze and/or control the steelmaking process.

  9. Adsorption modeling for off-gas treatment

    SciTech Connect

    Ladshaw, A.; Sharma, K.; Yiacoumi, S.; Tsouris, C.; De Paoli, D.W.

    2013-07-01

    Off-gas generated from the reprocessing of used nuclear fuel contains a mixture of several radioactive gases including {sup 129}I{sub 2}, {sup 85}Kr, HTO, and {sup 14}CO{sub 2}. Over the past few decades, various separation and recovery processes have been studied for capturing these gases. Adsorption data for gaseous mixtures of species can be difficult to determine experimentally. Therefore, procedures capable of predicting the adsorption behavior of mixtures need to be developed from the individual isotherms of each of the pure species. A particular isotherm model of interest for the pure species is the Generalized Statistical Thermodynamic Adsorption isotherm. This model contains an adjustable number of parameters and will therefore describe a wide range of adsorption isotherms for a variety of components. A code has been developed in C++ to perform the non-linear regression analysis necessary for the determination of the isotherm parameters, as well as the least number of parameters needed to describe an entire set of data. (authors)

  10. Iodine Pathways and Off-Gas Stream Characteristics for Aqueous Reprocessing Plants – A Literature Survey and Assessment

    SciTech Connect

    R. T. Jubin; D. M. Strachan; N. R. Soelberg

    2013-09-01

    Used nuclear fuel is currently being reprocessed in only a few countries, notably France, England, Japan, and Russia. The need to control emissions of the gaseous radionuclides to the air during nuclear fuel reprocessing has already been reported for the entire plant. But since the gaseous radionuclides can partition to various different reprocessing off-gas streams, for example, from the head end, dissolver, vessel, cell, and melter, an understanding of each of these streams is critical. These off-gas streams have different flow rates and compositions and could have different gaseous radionuclide control requirements, depending on how the gaseous radionuclides partition. This report reviews the available literature to summarize specific engineering data on the flow rates, forms of the volatile radionuclides in off-gas streams, distributions of these radionuclides in these streams, and temperatures of these streams. This document contains an extensive bibliography of the information contained in the open literature.

  11. Molecular simulation of a model of dissolved organic matter

    SciTech Connect

    Sutton, Rebecca; Sposito, Garrison; Diallo, Mamadou S.; Schulten,Hans-Rolf

    2004-11-08

    A series of atomistic simulations was performed to assess the ability of the Schulten dissolved organic matter (DOM) molecule, a well-established model humic molecule, to reproduce the physical and chemical behavior of natural humic substances. The unhydrated DOM molecule had a bulk density value appropriate to humic matter, but its Hildebrand solubility parameter was lower than the range of current experimental estimates. Under hydrated conditions, the DOM molecule went through conformational adjustments that resulted in disruption of intramolecular hydrogen bonds (H-bonds), although few water molecules penetrated the organic interior. The radius of gyration of the hydrated DOM molecule was similar to those measured for aquatic humic substances. To simulate humic materials under aqueous conditions with varying pH levels, carboxyl groups were deprotonated, and hydrated Na{sup +} or Ca{sup 2+} were added to balance the resulting negative charge. Because of intrusion of the cation hydrates, the model metal- humic structures were more porous, had greater solvent-accessible surface areas, and formed more H-bonds with water than the protonated, hydrated DOM molecule. Relative to Na{sup +}, Ca{sup 2+} was both more strongly bound to carboxylate groups and more fully hydrated. This difference was attributed to the higher charge of the divalent cation. The Ca-DOM hydrate, however, featured fewer H-bonds than the Na-DOM hydrate, perhaps because of the reduced orientational freedom of organic moieties and water molecules imposed by Ca{sup 2+}. The present work is, to our knowledge, the first rigorous computational exploration regarding the behavior of a model humic molecule under a range of physical conditions typical of soil and water systems.

  12. Development of silver impregnated alumina for iodine separation from off-gas streams

    SciTech Connect

    Funabashi, Kiyomi; Fukasawa, Tetsuo; Kikuchi, Makoto

    1995-02-01

    An inorganic iodine adsorbent, silver impregnated alumina (AgA), has been developed to separate iodine effectively from off-gas streams of nuclear facilities and to decrease the volume of waste (spent adsorbent). Iodine removal efficiency was improved at relatively high humidity by using alumina carrier with two different pore diameters. Waste volume reduction was achieved by impregnating relatively large amounts of silver into the alumina pores. The developed adsorbent was tested first with simulated off-gas streams under various experimental conditions and finally with actual off-gas streams of the Karlsruhe reprocessing plant. The decontamination factor (DF) was about 100 with the AgA bed depth of 2cm at 70% relative humidity, which was a DF one order higher than that when AgA with one pore size was used. Iodine adsorption capacity was checked by passing excess iodine into the AgA bed. Values were about 0.12 and 0.35 g-I/cm`-AgA bed for 10 and 24wt% silver impregnated AgA, respectively. The results obtained in this study demonstrated the applicability of the developed AgA to the off-gas treatment system of nuclear facilities.

  13. Sorption Modeling and Verification for Off-Gas Treatment

    SciTech Connect

    Tavlarides, Lawrence L.; Lin, Ronghong; Nan, Yue; Yiacoumi, Sotira; Tsouris, Costas; Ladshaw, Austin; Sharma, Ketki; Gabitto, Jorge; DePaoli, David

    2015-04-29

    The project has made progress toward developing a comprehensive modeling capability for the capture of target species in off gas evolved during the reprocessing of nuclear fuel. The effort has integrated experimentation, model development, and computer code development for adsorption and absorption processes. For adsorption, a modeling library has been initiated to include (a) equilibrium models for uptake of off-gas components by adsorbents, (b) mass transfer models to describe mass transfer to a particle, diffusion through the pores of the particle and adsorption on the active sites of the particle, and (c) interconnection of these models to fixed bed adsorption modeling which includes advection through the bed. For single-component equilibria, a Generalized Statistical Thermodynamic Adsorption (GSTA) code was developed to represent experimental data from a broad range of isotherm types; this is equivalent to a Langmuir isotherm in the two-parameter case, and was demonstrated for Kr on INL-engineered sorbent HZ PAN, water sorption on molecular sieve A sorbent material (MS3A), and Kr and Xe capture on metal-organic framework (MOF) materials. The GSTA isotherm was extended to multicomponent systems through application of a modified spreading pressure surface activity model and generalized predictive adsorbed solution theory; the result is the capability to estimate multicomponent adsorption equilibria from single-component isotherms. This advance, which enhances the capability to simulate systems related to off-gas treatment, has been demonstrated for a range of real-gas systems in the literature and is ready for testing with data currently being collected for multicomponent systems of interest, including iodine and water on MS3A. A diffusion kinetic model for sorbent pellets involving pore and surface diffusion as well as external mass transfer has been established, and a methodology was developed for determining unknown diffusivity parameters from transient

  14. Degradation of off-gas toluene in continuous pyrite Fenton system.

    PubMed

    Choi, Kyunghoon; Bae, Sungjun; Lee, Woojin

    2014-09-15

    Degradation of off-gas toluene from a toluene reservoir and a soil vapor extraction (SVE) process was investigated in a continuous pyrite Fenton system. The removal of off-gas toluene from the toluene reservoir was >95% by 8h in the pyrite Fenton system, while it was ∼97 % by 3h in classic Fenton system and then rapidly decreased to initial level by 8h. Continuous consumption of low Fe(II) concentration dissolved from pyrite surface (0.05-0.11 mM) was observed in the pyrite Fenton system, which can lead to the effective and successful removal of the gas-phase toluene due to stable production of OH radical (OH). Inhibitor and spectroscopic test results showed that OH was a dominant radical that degraded gas-phase toluene during the reaction. Off-gas toluene from the SVE process was removed by 96% in the pyrite Fenton system, and remnant toluene from rebounding effect was treated by 99%. Main transformation products from toluene oxidation were benzoic acid (31.4%) and CO2 (38.8%) at 4h, while traces of benzyl alcohol (1.3%) and benzaldehyde (0.7%) were observed. Maximum operation time of continuous pyrite Fenton system was estimated to be 56-61 d and its optimal operation time achieving emission standard was 28.9 d. PMID:25125037

  15. Determination of process conditions for the spray nozzle for the DWPF melter off-gas HEME

    SciTech Connect

    Lee, L.

    1991-12-15

    The DWPF melter off-gas systems have High Efficiency Mist Eliminators (HEME) upstream of the High Efficiency Particulates Air filters (HEPA) to remove fine mist and particulates from the off-gas. To have an acceptable filter life and an efficient HEME operation, air atomized water is sprayed into the melter off-gas and onto the HEME surface. The water spray keeps the HEME wet, which dissolves the soluble particulates and enhances the HEME efficiency. DWPF Technical requested SRL to determine the conditions for the DWPF nozzle which will give complete atomization of water so that the HEME will operate efficiently. Since the air pressure and flow rate to generate the desired spray are not known before hand, an experiment was performed in two stages. The first stage involved preliminary tests which mapped out a general operating region for producing the desired spray pattern. Afterward, all the gages and meters were changed to suitable ranges for the conditions which generated an acceptable spray. This report summarizes the results and the conclusions of the second stage experiment.

  16. Simulation Analysis for HB-Line Dissolver Mixing

    SciTech Connect

    Lee, S

    2006-03-22

    In support of the HB-Line Engineering agitator mixing project, flow pattern calculations have been made for a 90{sup o} apart and helical pitch agitator submerged in a flat tank containing dissolver baskets. The work is intended to determine maximum agitator speed to keep the dissolver baskets from contacting the agitator for the nominal tank liquid level. The analysis model was based on one dissolver basket located on the bottom surface of the flat tank for a conservative estimate. The modeling results will help determine acceptable agitator speeds and tank liquid levels to ensure that the dissolver basket is kept from contacting the agitator blade during HB-Line dissolver tank operations. The numerical modeling and calculations have been performed using a computational fluid dynamics approach. Three-dimensional steady-state momentum and continuity equations were used as the basic equations to estimate fluid motion driven by an agitator with four 90{sup o} pitched blades or three flat blades. Hydraulic conditions were fully turbulent (Reynolds number about 1 x 10{sup 5}). A standard two-equation turbulence model ({kappa},{var_epsilon}), was used to capture turbulent eddy motion. The commercial finite volume code, Fluent [5], was used to create a prototypic geometry file with a non-orthogonal mesh. Hybrid meshing was used to fill the computational region between the round-edged tank bottom and agitator regions. The nominal calculations and a series of sensitivity runs were made to investigate the impact of flow patterns on the lifting behavior of the dissolver basket. At high rotational speeds and low tank levels, local turbulent flow reaches the critical condition for the dissolver basket to be picked up from the tank floor and to touch the agitator blades during the tank mixing operations. This is not desirable in terms of mixing performance. The modeling results demonstrate that the flow patterns driven by the agitators considered here are not strong enough to

  17. SIMULATION OF DISSOLVED OXYGEN PROFILES IN A TRANSPARENT, DIMICTIC LAKE

    EPA Science Inventory

    Thrush Lake is a small, highly transparent lake in northeastern Minnesota. rom 1986 to 1991, vertical profiles of water temperature, dissolved oxygen, chlorophyll a concentration, underwater light irradiance, and Secchi depths were measured at monthly intervals during the ice-fre...

  18. Numerical Simulation of Salinity and Dissolved Oxygen at Perdido Bay and Adjacent Coastal Ocean

    EPA Science Inventory

    Environmental Fluid Dynamic Code (EFDC), a numerical estuarine and coastal ocean circulation hydrodynamic model, was used to simulate the distribution of the salinity, temperature, nutrients and dissolved oxygen (DO) in Perdido Bay and adjacent Gulf of Mexico. External forcing fa...

  19. HC-21C off-gas test procedure. Revision 1

    SciTech Connect

    Cunningham, L.T.

    1995-02-02

    Stabilization of plutonium bearing scrap material occurs in furnaces, FUR-21C-1 and FUR-21C-2, located in glovebox HC-21C. During previous testing and processing operations, water has been observed forming in the off-gas rotameters, FI-21C-1 and FI-21C-2. The off-gas is filtered through a 2 micron ceramic filter, F-21C-1 or F-21C-2, before discharge into the 26 inch vacuum system. The goal of this test plan is to determine the cause and location of water formation in the sludge stabilization off-gas system. The results should help determine what design improvements or processing steps will be implemented to prevent this phenomena from occurring in the future.

  20. Dissolved carbon in extreme conditions characterized by first principles simulations

    NASA Astrophysics Data System (ADS)

    Pan, Ding; Galli, Giulia

    One key component to understanding carbon transport in the Earth interior is the determination of the molecular species formed when carbon bearing materials are dissolved in water at extreme conditions. We used first principles molecular dynamics to investigate oxidized carbon in water at high pressure (P) and high temperature (T), up to the conditions of the Earth's upper mantle. Contrary to popular geochemistry models assuming that CO2 is the major carbon species present in water, we found that most of the dissolved carbon at 10 GPa and 1000 K is in the form of solvated CO32- and HCO3-anions. We also found that ion pairing between alkali metal cations and CO32- or HCO3-anions is greatly affected by P-T conditions, decreasing with pressure along an isotherm. Our study shows that it is crucial to take into account the specific molecular structure of water under extreme conditions and the changes in hydrogen bonding occurring at high P and T, in order to predict chemical reactions in dissolved carbon. Our findings also shed light on possible reduction mechanisms of CO2 when it is geologically stored, depending on the availability of water. The work is supported by the Sloan Foundation through the Deep Carbon Observatory.

  1. HC-21C off-gas test procedure

    SciTech Connect

    Cunningham, L.T.

    1994-12-14

    The goal of this test plan is to determine the cause and location of water formation in the sludge stabilization off-gas system. The results should help determine what design improvements or processing steps will be implemented to prevent this phenomena from occurring in the future. This test procedure will include a series of tests to determine where and why liquid is condensing in the HC-21C furnace off-gas system. The tests will take a sequential, graded approach and may be concluded one the results have satisfactorily resolved the problem.

  2. CHARACTERIZATION OF DWPF MELTER OFF-GAS QUENCHER SAMPLE

    SciTech Connect

    Newell, J.

    2011-11-14

    The Savannah River National Laboratory (SRNL) recently received a deposit sample from the Melter Primary Off Gas System (POG) of the Defense Waste Processing Facility (DWPF). This sample was composed of material that had been collected while the quencher was in operation January 27, 2011 through March 31, 2011. DWPF requested, through a technical assistance request, characterization of the melter off-gas deposits by x-ray diffraction (XRD), scanning electron microscopy (SEM), and chemical analysis. The purpose of the Melter Off-Gas System is to reduce the amount of radioactive particles and mercury in the gases vented to the atmosphere. Gases emitted from the melter pass through the primary film cooler, quencher, Off-Gas Condensate Tank (OGCT), Steam Atomized Scrubbers (SAS), a condenser, a high efficiency mist eliminator, and a high efficiency particulate air filter, before being vented to the Process Vessel Vent System. The film coolers cool the gases leaving the melter vapor space from {approx}750 C to {approx}375 C, by introducing air and steam to the flow. In the next step, the quencher cools the gas to about 60 C by bringing the condensate from the OGCT in contact with the effluent (Figure 1). Most of the steam in the effluent is then condensed and the melter vapor space pressure is reduced. The purpose of the OGCT is to collect and store the condensate formed during the melter operation. Condensate from the OGCT is circulated to the SAS and atomized with steam. This atomized condensate is mixed with the off-gas to wet and join the particulate which is then removed in the cyclone. The next stage incorporates a chilled water condenser which separates the vapors and elemental mercury from the off-gas steam. Primary off-gas deposit samples from the DWPF melter have previously been analyzed. In 2003, samples from just past the film cooler, from the inlet of the quencher and inside the quencher were analyzed at SRNL. It was determined that the samples were a

  3. Dissolved:total metals concentrations in marine acute toxicity test simulations

    SciTech Connect

    Lussier, S.M.; Boothman, W.S.; Champlin, D.; Poucher, S.; Helmstetter, A.

    1995-12-31

    Use of water quality criteria expressed as dissolved metal is recommended by the US EPA, Office of Water, because ``dissolved metal more closely approximates the bioavailable fraction of metal in the water column than does total recoverable metal.`` Water quality criteria (WQC) are expressed in terms of total recoverable or acid-soluble metals concentrations; in part because few toxicity tests with aquatic organisms include measurement of dissolved metals. Therefore, if WQC are to be expressed as dissolved, complete retesting or derivation of dissolved:total (D:T) metals relationships to adjust existing criteria were required. To derive D:T ratios, simulated tests were conducted using concentrations and species similar to those used to derive original criteria. Dissolved (<0.45/{micro}) and total recoverable metals were measured to determine the partitioning relationship under these experimental conditions and convert criteria to reflect dissolved metals concentrations. Simulations were conducted with arsenic (III), cadmium, chromium (VI), lead, nickel, selenium, and zinc. In all simulations, average dissolved metals comprised 93--100% of total metals measured. Dissolved:total ratios did not significantly differ for a given metal throughout each test among test type or treatment concentration. Biological results, while insufficient to derive criteria directly, were generally consistent with results of historical biological response data. These results demonstrate that, under the conditions employed, i.e, short exposure periods (2--4 days) and low particulate load typical of these tests, metals are essentially not removed from solution onto particles. This does not imply that such partitioning is representative of conditions in natural waters, but rather that in the historical acute toxicity tests used to establish water quality criteria, metals were primarily dissolved.

  4. Simple hobby computer-based off-gas analysis system

    SciTech Connect

    Forrest, E.H.; Jansen, N.B.; Flickinger, M.C.; Tsao, G.T.

    1981-02-01

    An Apple II computer has been adapted to monitor fermentation offgas in laboratory and pilot scale fermentors. It can calculate oxygen uptake rates, carbon dioxide evolution rates, respiratory quotient as well as initiating recalibration procedures. In this report the computer-based off-gas analysis system is described.

  5. Simulation of hydrodynamics, temperature, and dissolved oxygen in Beaver Lake, Arkansas, 1994-1995

    USGS Publications Warehouse

    Haggard, Brian; Green, W. Reed

    2002-01-01

    The tailwaters of Beaver Lake and other White River reservoirs support a cold-water trout fishery of significant economic yield in northwestern Arkansas. The Arkansas Game and Fish Commission has requested an increase in existing minimum flows through the Beaver Lake dam to increase the amount of fishable waters downstream. Information is needed to assess the impact of additional minimum flows on temperature and dissolved-oxygen qualities of reservoir water above the dam and the release water. A two-dimensional, laterally averaged hydrodynamic, thermal and dissolved-oxygen model was developed and calibrated for Beaver Lake, Arkansas. The model simulates surface-water elevation, currents, heat transport and dissolved-oxygen dynamics. The model was developed to assess the impacts of proposed increases in minimum flows from 1.76 cubic meters per second (the existing minimum flow) to 3.85 cubic meters per second (the additional minimum flow). Simulations included assessing (1) the impact of additional minimum flows on tailwater temperature and dissolved-oxygen quality and (2) increasing initial water-surface elevation 0.5 meter and assessing the impact of additional minimum flow on tailwater temperatures and dissolved-oxygen concentrations. The additional minimum flow simulation (without increasing initial pool elevation) appeared to increase the water temperature (<0.9 degrees Celsius) and decrease dissolved oxygen concentration (<2.2 milligrams per liter) in the outflow discharge. Conversely, the additional minimum flow plus initial increase in pool elevation (0.5 meter) simulation appeared to decrease outflow water temperature (0.5 degrees Celsius) and increase dissolved oxygen concentration (<1.2 milligrams per liter) through time. However, results from both minimum flow scenarios for both water temperature and dissolved oxygen concentration were within the boundaries or similar to the error between measured and simulated water column profile values.

  6. ART CCIM Phase II-A Off-Gas System Evaluation Test Plan

    SciTech Connect

    Nick Soelberg; Jay Roach

    2009-01-01

    This test plan defines testing to be performed using the Idaho National Laboratory (INL) engineering-scale cold crucible induction melter (CCIM) test system for Phase II-A of the Advanced Remediation Technologies (ART) CCIM Project. The multi-phase ART-CCIM Project is developing a conceptual design for replacing the joule-heated melter (JHM) used to treat high level waste (HLW) in the Defense Waste Processing Facility (DWPF) at the Savannah River Site (SRS) with a cold crucible induction melter. The INL CCIM test system includes all feed, melter off-gas control, and process control subsystems needed for fully integrated operation and testing. Testing will include operation of the melter system while feeding a non-radioactive slurry mixture prepared to simulate the same type of waste feed presently being processed in the DWPF. Process monitoring and sample collection and analysis will be used to characterize the off-gas composition and properties, and to show the fate of feed constituents, to provide data that shows how the CCIM retrofit conceptual design can operate with the existing DWPF off-gas control system.

  7. Hanford Low-Activity Waste Processing: Demonstration of the Off-Gas Recycle Flowsheet - 13443

    SciTech Connect

    Ramsey, William G.; Esparza, Brian P.

    2013-07-01

    Vitrification of Hanford Low-Activity Waste (LAW) is nominally the thermal conversion and incorporation of sodium salts and radionuclides into borosilicate glass. One key radionuclide present in LAW is technetium-99. Technetium-99 is a low energy, long-lived beta emitting radionuclide present in the waste feed in concentrations on the order of 1-10 ppm. The long half-life combined with a high solubility in groundwater results in technetium-99 having considerable impact on performance modeling (as potential release to the environment) of both the waste glass and associated secondary waste products. The current Hanford Tank Waste Treatment and Immobilization Plant (WTP) process flowsheet calls for the recycle of vitrification process off-gas condensates to maximize the portion of technetium ultimately immobilized in the waste glass. This is required as technetium acts as a semi-volatile specie, i.e. considerable loss of the radionuclide to the process off-gas stream can occur during the vitrification process. To test the process flowsheet assumptions, a prototypic off-gas system with recycle capability was added to a laboratory melter (on the order of 1/200 scale) and testing performed. Key test goals included determination of the process mass balance for technetium, a non-radioactive surrogate (rhenium), and other soluble species (sulfate, halides, etc.) which are concentrated by recycling off-gas condensates. The studies performed are the initial demonstrations of process recycle for this type of liquid-fed melter system. This paper describes the process recycle system, the waste feeds processed, and experimental results. Comparisons between data gathered using process recycle and previous single pass melter testing as well as mathematical modeling simulations are also provided. (authors)

  8. Simulation of hydrodynamics, temperature, and dissolved oxygen in Norfork Lake, Arkansas, 1994-1995

    USGS Publications Warehouse

    Galloway, Joel M.; Green, W. Reed

    2002-01-01

    Outflow from Norfork Lake and other White River reservoirs support a cold-water trout fishery of significant economic yield in north-central Arkansas and south-central Missouri. The Arkansas Game and Fish Commission has requested an increase in existing minimum flows through the Norfork Lake dam to increase the amount of fishable waters downstream. Information is needed to assess the impact of increased minimum flows on temperature and dissolved-oxygen concentrations of reservoir water and the outflow. A two-dimensional, laterally averaged, hydrodynamic, temperature, and dissolved-oxygen model was developed and calibrated for Norfork Lake, located on the Arkansas-Missouri State line. The model simulates water-surface elevation, heat transport, and dissolved-oxygen dynamics. The model was developed to assess the impacts of proposed increases in minimum flow from 1.6 cubic meter per second (the existing minimum flow) to 8.5 cubic meters per second (the increased minimum flow). Simulations included assessing the impact of (1) increased minimum flows and (2) increased minimum flows with increased water-surface elevation of 1.1 meter in Norfork Lake on outflow temperatures and dissolved-oxygen concentrations. The increased minimum flow simulation (without increasing initial water-surface elevation) appeared to increase the water temperature and decrease dissolved-oxygen concentration in the outflow. Conversely, the increased minimum flow and initial increase in water-surface elevation (1.1 meter) simulation appeared to decrease outflow water temperature and increase dissolved-oxygen concentration through time. However, results from both scenarios for water temperature and dissolved-oxygen concentration were within the boundaries or similar to the error between measured and simulated water column profile values.

  9. FY-2001 Accomplishments in Off-gas Treatment Technology Development

    SciTech Connect

    Marshall, Douglas William

    2001-09-01

    This report summarizes the efforts funded by the Tank Focus Area to investigate nitrogen oxide (NOx) destruction (a.k.a. deNOx) technologies and off-gas scrubber system designs. The primary deNOx technologies that were considered are staged combustion (a.k.a. NOx reburning), selective catalytic reduction, selective non-catalytic reduction, and steam reformation. After engineering studies and a team evaluation were completed, selective catalytic reduction and staged combustion were considered the most likely candidate technologies to be deployed in a sodium-bearing waste vitrification facility. The outcome of the team evaluation factored heavily in the establishing a baseline configuration for off-gas and secondary waste treatment systems.

  10. Microwave off-gas treatment apparatus and process

    DOEpatents

    Schulz, Rebecca L.; Clark, David E.; Wicks, George G.

    2003-01-01

    The invention discloses a microwave off-gas system in which microwave energy is used to treat gaseous waste. A treatment chamber is used to remediate off-gases from an emission source by passing the off-gases through a susceptor matrix, the matrix being exposed to microwave radiation. The microwave radiation and elevated temperatures within the combustion chamber provide for significant reductions in the qualitative and quantitative emissions of the gas waste stream.

  11. Test results from the GA technologies engineering-scale off-gas treatment system

    SciTech Connect

    Jensen, D.D.; Olguin, L.J.; Wilbourn, R.G.

    1984-06-01

    One method for reducing the volume of HTGR fuel prior to reprocessing or spent fuel storage is to crush and burn the graphite fuel elements. The burner off-gas (BOG) contains radioactive components, principally H-3, C-14, Kr-85, I-129, and Rn-220, as well as chemical forms such as CO/sub 2/, CO, O/sub 2/, and SO/sub 2/. The BOG system employs components designed to remove these constitutents. Test results are reported for the iodine and SO/sub 2/ adsorbers and the CO/HT oxidizer. Silver-based iodine adsorbents were found to catalyze the premature conversion of CO to CO/sub 2/. Subsequent tests showed that iodine removal could not be performed downstream of the CO/HT oxidizer since iodine in the BOG system rapidly deactivated the Pt-coated alumina CO catalyst. Lead-exchanged zeolite (PbX) was found to be an acceptable alternative for removing iodine from BOG without CO conversion. Intermittent and steady-state tests of the pilot-plant SO/sub 2/ removal unit containing sodium-exchanged zeolite (NaX) demonstrated that decontamination factors greater than or equal to 100 could be maintained for up to 50 h. In a reprocessing flowsheet, the solid product from the burners is dissolved in nitric or Thorex acid. The dissolver off-gas (DOG) contains radioactive components H-3, Kr-85, I-129, Rn-220 plus chemical forms such as nitrogen oxides (NO/sub x/). In the pilot-scale system at GA, iodine is removed from the DOG by adsorption. Tests of iodine removal have been conducted using either silver-exchanged mordenite (AgZ) or AgNO/sub 3/-impregnated silica gel (AC-6120). Although each sorbent performed well in the presence of NO/sub x/, the silica gel adsorbent proved more efficient in silver utilization and, thus, more cost effective.

  12. MODEL SIMULATIONS OF DISSOLVED OXYGEN CHARACTERISTICS OF MINNESOTA LAKES: PAST AND FUTURE

    EPA Science Inventory

    A deterministic, one-dimensional, unsteady numerical model has been developed, tested, and applied to simulate mean daily dissolved oxygen (DO) characteristics in 27 lake classes in the state of Minnesota. eaeration and photosynthesis are the oxygen sources, while respiration, se...

  13. DIEL FLUX OF DISSOLVED CARBOHYDRATE IN A SALT MARSH AND A SIMULATED ESTUARINE ECOSYSTEM

    EPA Science Inventory

    The concentrations of total dissolved carbohydrate (TCHO), monosaccharide (MCHO) and polysaccharide (PCHO) were followed over a total of ten diel cycles in a salt marsh and a 13 cu m seawater tank simulating an estuarine ecosystem. Their patterns are compared to those for total d...

  14. SIMULATED CLIMATE CHANGE EFFECTS ON DISSOLVED OXYGEN CHARACTERISTICS IN ICE-COVERED LAKES. (R824801)

    EPA Science Inventory

    A deterministic, one-dimensional model is presented which simulates daily dissolved oxygen (DO) profiles and associated water temperatures, ice covers and snow covers for dimictic and polymictic lakes of the temperate zone. The lake parameters required as model input are surface ...

  15. Simulation of hydrodynamics, temperature, and dissolved oxygen in Table Rock Lake, Missouri, 1996-1997

    USGS Publications Warehouse

    Green, W. Reed; Galloway, Joel M.; Richards, Joseph M.; Wesolowski, Edwin A.

    2003-01-01

    Outflow from Table Rock Lake and other White River reservoirs support a cold-water trout fishery of substantial economic yield in south-central Missouri and north-central Arkansas. The Missouri Department of Conservation has requested an increase in existing minimum flows through the Table Rock Lake Dam from the U.S. Army Corps of Engineers to increase the quality of fishable waters downstream in Lake Taneycomo. Information is needed to assess the effect of increased minimum flows on temperature and dissolved- oxygen concentrations of reservoir water and the outflow. A two-dimensional, laterally averaged, hydrodynamic, temperature, and dissolved-oxygen model, CE-QUAL-W2, was developed and calibrated for Table Rock Lake, located in Missouri, north of the Arkansas-Missouri State line. The model simulates water-surface elevation, heat transport, and dissolved-oxygen dynamics. The model was developed to assess the effects of proposed increases in minimum flow from about 4.4 cubic meters per second (the existing minimum flow) to 11.3 cubic meters per second (the increased minimum flow). Simulations included assessing the effect of (1) increased minimum flows and (2) increased minimum flows with increased water-surface elevations in Table Rock Lake, on outflow temperatures and dissolved-oxygen concentrations. In both minimum flow scenarios, water temperature appeared to stay the same or increase slightly (less than 0.37 ?C) and dissolved oxygen appeared to decrease slightly (less than 0.78 mg/L) in the outflow during the thermal stratification season. However, differences between the minimum flow scenarios for water temperature and dissolved- oxygen concentration and the calibrated model were similar to the differences between measured and simulated water-column profile values.

  16. Process for off-gas particulate removal and apparatus therefor

    DOEpatents

    Carl, Daniel E.

    1997-01-01

    In the event of a breach in the off-gas line of a melter operation requiring closure of the line, a secondary vessel vent line is provided with a particulate collector utilizing atomization for removal of large particulates from the off-gas. The collector receives the gas containing particulates and directs a portion of the gas through outer and inner annular channels. The collector further receives a fluid, such as water, which is directed through the outer channel together with a second portion of the particulate-laden gas. The outer and inner channels have respective ring-like termination apertures concentrically disposed adjacent one another on the outer edge of the downstream side of the particulate collector. Each of the outer and inner channels curves outwardly away from the collector's centerline in proceeding toward the downstream side of the collector. Gasflow in the outer channel maintains the fluid on the channel's wall in the form of a "wavy film," while the gas stream from the inner channel shears the fluid film as it exits the outer channel in reducing the fluid to small droplets. Droplets formed by the collector capture particulates in the gas stream by one of three mechanisms: impaction, interception or Brownian diffusion in removing the particulates. The particulate-laden droplets are removed from the fluid stream by a vessel vent condenser or mist eliminator.

  17. Process for off-gas particulate removal and apparatus therefor

    DOEpatents

    Carl, D.E.

    1997-10-21

    In the event of a breach in the off-gas line of a melter operation requiring closure of the line, a secondary vessel vent line is provided with a particulate collector utilizing atomization for removal of large particulates from the off-gas. The collector receives the gas containing particulates and directs a portion of the gas through outer and inner annular channels. The collector further receives a fluid, such as water, which is directed through the outer channel together with a second portion of the particulate-laden gas. The outer and inner channels have respective ring-like termination apertures concentrically disposed adjacent one another on the outer edge of the downstream side of the particulate collector. Each of the outer and inner channels curves outwardly away from the collector`s centerline in proceeding toward the downstream side of the collector. Gas flow in the outer channel maintains the fluid on the channel`s wall in the form of a ``wavy film,`` while the gas stream from the inner channel shears the fluid film as it exits the outer channel in reducing the fluid to small droplets. Droplets formed by the collector capture particulates in the gas stream by one of three mechanisms: impaction, interception or Brownian diffusion in removing the particulates. The particulate-laden droplets are removed from the fluid stream by a vessel vent condenser or mist eliminator. 4 figs.

  18. Cooler and particulate separator for an off-gas stack

    DOEpatents

    Wright, George T.

    1992-01-01

    An off-gas stack for a melter comprising an air conduit leading to two sets of holes, one set injecting air into the off-gas stack near the melter plenum and the second set injecting air downstream of the first set. The first set injects air at a compound angle, having both downward and tangential components, to create a reverse vortex flow, counter to the direction of flow of gas through the stack and also along the periphery of the stack interior surface. Air from the first set of holes pervents recirculation zones from forming and the attendant accumulation of particulate deposits on the wall of the stack and will also return to the plenum any particulate swept up in the gas entering the stack. The second set of holes injects air in the same direction as the gas in the stack to compensate for the pressure drop and to prevent the concentration of condensate in the stack. A set of sprayers, receiving water from a second conduit, is located downstream of the second set of holes and sprays water into the gas to further cool it.

  19. Cooler and particulate separator for an off-gas stack

    DOEpatents

    Wright, G.T.

    1991-04-08

    This report describes an off-gas stack for a melter, furnace or reaction vessel comprising an air conduit leading to two sets of holes, one set injecting air into the off-gas stack near the melter plenum and the second set injecting air downstream of the first set. The first set injects air at a compound angle, having both downward and tangential components, to create a reverse vortex flow, counter to the direction of flow of gas through the stack and also along the periphery of the stack interior surface. Air from the first set of holes prevents recirculation zones from forming and the attendant accumulation of particulate deposits on the wall of the stack and will also return to the plenum any particulate swept up in the gas entering the stack. The second set of holes injects air in the same direction as the gas in the stack to compensate for the pressure drop and to prevent the concentration of condensate in the stack. A set of sprayers, receiving water from a second conduit, is located downstream of the second set of holes and sprays water into the gas to further cool it.

  20. Simulated effects of surface coal mining and agriculture on dissolved solids in the Redwater River, east-central Montana

    USGS Publications Warehouse

    Ferreira, R.F.; Lambing, J.H.

    1985-01-01

    Dissolved solids concentrations in five reaches of the Redwater River in east-central Montana were simulated to evaluate the effects of surface coal mining and agriculture. A mass-balance model of streamflow and dissolved solids load developed for the Tongue River in southeastern Montana was modified and applied to the Redwater River. Mined acreages, dissolved solids concentrations in mined spoils, and irrigated acreage can be varied in the model to study relative changes in the dissolved solids concentration in consecutive reaches of the river. Because of extreme variability and a limited amount of data, the model was not consecutively validated. Simulated mean and median monthly mean streamflows and consistently larger than those calculated from streamflow records. Simulated mean and median monthly mean dissolved solids loads also are consistently larger than regression-derived values. These discrepancies probably result from extremely variable streamflow, overestimates of streamflow from ungaged tributaries, and weak correlations between streamflow and dissolved solids concentrations. The largest increases in simulated dissolved solids concentrations from mining and agriculture occur from September through January because of smaller streamflows and dissolved solids loads. Different combinations of agriculture and mining under mean flow conditions resulted in cumulative percentage increases of dissolved solids concentrations of less than 5% for mining and less than 2% for agriculture. (USGS)

  1. ART CCIM PHASE II-A OFF-GAS SYSTEM EVALUATION TEST REPORT

    SciTech Connect

    Nick Soelberg

    2009-04-01

    AREVA Federal Services (AFS) is performing a multi-year, multi-phase Advanced Remediation Technologies (ART) project, sponsored by the U.S. Department of Energy (DOE), to evaluate the feasibility and benefits of replacing the existing joule-heated melter (JHM) used to treat high level waste (HLW) in the Defense Waste Processing Facility (DWPF) at the Savannah River Site with a cold crucible induction melter (CCIM). The AFS ART CCIM project includes several collaborators from AREVA subsidiaries, French companies, and DOE national laboratories. The Savannah River National Laboratory and the Commissariat a l’Energie Atomique (CEA) have performed laboratory-scale studies and testing to determine a suitable, high-waste-loading glass matrix. The Idaho National Laboratory (INL) and CEA are performing CCIM demonstrations at two different pilot scales to assess CCIM design and operation for treating SRS sludge wastes that are currently being treated in the DWPF. SGN is performing engineering studies to validate the feasibility of retrofitting CCIM technology into the DWPF Melter Cell. The long-term project plan includes more lab-testing, pilot- and large-scale demonstrations, and engineering activities to be performed during subsequent project phases. A simulant of the DWPF SB4 feed was successfully fed and melted in a small pilot-scale CCIM system during two test series. The OGSE tests provide initial results that (a) provide melter operating conditions while feeding a DWPF SB4 simulant feed, (b) determine the fate of feed organic and metal feed constituents and metals partitioning, and (c) characterize the melter off-gas source term to a downstream off-gas system. The INL CCIM test system was operated continuously for about 30 hours during the parametric test series, and for about 58 hours during the OGSE test. As the DWPF simulant feed was continuously fed to the melter, the glass level gradually increased until a portion of the molten glass was drained from the melter

  2. Materials performance in off-gas systems containing iodine

    SciTech Connect

    Beavers, J.A.; Berry, W.E.; Griess, J.C.

    1981-11-01

    During the reprocessing of spent reactor fuel elements, iodine is released to gas streams from which it is ultimately removed by conversion to nonvolatile iodic acid. Under some conditions iodine can produce severe corrosion in off-gas lines; in this study these conditions were established. Iron- and nickel-based alloys containing more than 6% molybdenum, such as Hastelloy G (7%), Inconel 625 (9%), and Hastelloy C-276 (16%), as well as titanium and zirconium, remained free of attack under all conditions tested. When the other materials, notably the austenitic stainless steels, were exposed to gas streams containing even only low concentrations of iodine and water vapors at 25 and 40/sup 0/C, a highly corrosive, brownish-green liquid formed on their surfaces. In the complete absence of water vapor, the iodine-containing liquid did not form and all materials remained unaffected. The liquid that formed had a low pH (usually < 1), and the attack was about the same in either air or nitrogen. The rate of attack increased with increasing temperature at constant relative humidity but decreased with increasing temperature at constant water content. The severity of attack increased with the increasing water content of the gas except under conditions where relatively large amounts of water were present, such as on a condensing surface. Nitric acid and NO/sub 2/ inhibited attack.

  3. Literature search for offsite data to improve the DWPF melter off-gas model

    SciTech Connect

    Daniel, W.E.

    2000-05-04

    This report documents the literature search performed and any relevant data that may help relax some of the constraints on the DWPF melter off-gas model. The objective of this task was to look for outside sources of technical data to help reduce some of the conservatism built in the DWPF melter off-gas model.

  4. Assessment of the impact of the next generation solvent on DWPF melter off-gas flammability

    SciTech Connect

    Daniel, W. E.

    2013-02-13

    An assessment has been made to evaluate the impact on the DWPF melter off-gas flammability of replacing the current solvent used in the Modular Caustic-Side Solvent Extraction Process Unit (MCU) process with the Next Generation Solvent (NGS-MCU) and blended solvent. The results of this study showed that the concentrations of nonvolatile carbon and hydrogen of the current solvent in the Slurry Mix Evaporator (SME) product would both be about 29% higher than their counterparts of the NGS-MCU and blended solvent in the absence of guanidine partitioning. When 6 ppm of guanidine (TiDG) was added to the effluent transfer to DWPF to simulate partitioning for the NGS-MCU and blended solvent cases and the concentration of Isopar{reg_sign} L in the effluent transfer was controlled below 87 ppm, the concentrations of nonvolatile carbon and hydrogen of the NGS-MCU and blended solvent were still about 12% and 4% lower, respectively, than those of the current solvent. It is, therefore, concluded that as long as the volume of MCU effluent transfer to DWPF is limited to 15,000 gallons per Sludge Receipt and Adjustment Tank (SRAT)/SME cycle and the concentration of Isopar{reg_sign} L in the effluent transfer is controlled below 87 ppm, using the current solvent assumption of 105 ppm Isopar{reg_sign} L or 150 ppm solvent in lieu of NGS-MCU or blended solvent in the DWPF melter off-gas flammability assessment is conservative for up to an additional 6 ppm of TiDG in the effluent due to guanidine partitioning. This report documents the calculations performed to reach this conclusion.

  5. Simulating the effects of fluctuating dissolved oxygen on growth, reproduction, and survival of fish and shrimp.

    PubMed

    Miller Neilan, Rachael; Rose, Kenneth

    2014-02-21

    Individuals are commonly exposed to fluctuating levels of stressors, while most laboratory experiments focus on constant exposures. We develop and test a mathematical model for predicting the effects of low dissolved oxygen (hypoxia) on growth, reproduction, and survival using laboratory experiments on fish and shrimp. The exposure-effects model simulates the hourly reductions in growth and survival, and the reduction in reproduction (fecundity) at times of spawning, of an individual as it is exposed to constant or hourly fluctuating dissolved oxygen (DO) concentrations. The model was applied to seven experiments involving fish and shrimp that included constant and fluctuating DO exposures, with constant exposures used for parameter estimation and the model then used to simulate the growth, reproduction, and survival in the fluctuating treatments. Cumulative effects on growth, reproduction, and survival were predicted well by the model, but the model did not replay the observed episodic low survival days. Further investigation should involve the role of acclimation, possible inclusion of repair effects in reproduction and survival, and the sensitivity of model predictions to the shape of the immediate effects function. Additional testing of the model with other taxa, different patterns of fluctuating exposures, and different stressors is needed to determine the model's generality and robustness. PMID:24269807

  6. Dissolved Organic Phosphorus Production during Simulated Phytoplankton Blooms in a Coastal Upwelling System

    PubMed Central

    Ruttenberg, K. C.; Dyhrman, S. T.

    2012-01-01

    Dissolved organic phosphorus (DOP) is increasingly recognized as an important phosphorus source to marine primary producers. Despite its importance, the production rate and fate of DOP is poorly understood. In this study, patterns of DOP production were evaluated by tracking the evolution of DOP during simulated phytoplankton blooms initiated with nutrient amended surface waters, relative to controls, from the Oregon (USA) coastal upwelling system. Nitrogen (N) and phosphorus (P) additions were used to decouple DOP production and hydrolysis by inducing or repressing, respectively, community alkaline phosphatase activity. In order to examine the progression of nutrient uptake and DOP production under upwelling versus relaxation conditions, two experiments were initiated with waters collected during upwelling events, and two with waters collected during relaxation events. Maximum [under (+P) conditions] and minimum [under (+N) conditions] DOP production rates were calculated and applied to in situ DOP levels to evaluate which end-member rate most closely approximates the in situ DOP production rate at the four study sites in this coastal system. Increases in DOP concentration occurred by day-5 in control treatments in all experiments. N treatments displayed increased chlorophyll a, increased alkaline phosphatase activity, and yielded lower net DOP production rates relative to controls, suggesting that DOP levels were depressed as a consequence of increased hydrolysis of bioavailable DOP substrates. Phosphorus additions resulted in a significant net production of DOP at all stations, but no increase in chlorophyll a relative to control treatments. The contrasting patterns in DOP production between treatments suggests that changes in the ambient dissolved inorganic nitrogen:dissolved inorganic phosphorus (DIN:DIP) ratio could exert profound control over DOP production rates in this system. Patterns of DOP production across the different experiments also suggest that

  7. Development of off-gas emission kinetics for stored wood pellets.

    PubMed

    Fan, Chuigang; Bi, Xiaotao T

    2013-01-01

    A lumped three-reaction kinetic model for off-gas emissions of stored wood pellets in sealed containers has been developed accounting for the formation of CO and CO(2) and the depletion of O(2). Off-gas emission data at different conditions were used to extract kinetic model parameters by numerically fitting the proposed model equations. The fitted kinetic model parameters for different cases showed consistency with one another. With properly estimated model parameters, the current kinetic model can be used to predict off-gas emissions, oxygen depletion, and the buildup of toxic air pollutants in wood pellet storage containers/vessels. PMID:22826538

  8. Simulations of Mixing and Transport of Dissolved Waste Discharged From a Submerged Aquaculture pen

    NASA Astrophysics Data System (ADS)

    Venayagamoorthy, S. K.; Fringer, O. B.; Koseff, J. R.; Naylor, R. L.

    2007-05-01

    The present study focuses on understanding the transport and fate of dissolved wastes from an aquaculture pen in near-coastal environments using the hydrodynamic code SUNTANS, which uses unstructured grids to compute flows at very high resolution. Simulations of the pollutant concentration field (in time and space) as a function of the local environment (stratification, bathymetry, wind), flow conditions (tides, currents), and the location of the pen were performed. The fish-pen causes partial blockage of the water flow, causing deceleration of the approaching flow and the formation of a downstream wake. Results of both the near-field (area within 10 to 20 pen diameters of fish-pen site) as well as the far-field behavior of the pollutant field will be presented. The results provide an understanding of the impact of aquaculture fish-pens on coastal water quality.

  9. Off-Gas Analysis During the Vitrification of Hanford Radioactive Waste Samples

    SciTech Connect

    Ha, B.C.; Ferrara, D.M.; Crawford, C.L.; Choi, A.S.; Bibler, N.E.

    1998-03-01

    This paper describes the off-gas analysis of samples collected during the radioactive vitrification experiments. Production and characterization of the Hanford waste-containing LAW and HAW glasses are presented in related reports from this conference.

  10. Anode shroud for off-gas capture and removal from electrolytic oxide reduction system

    SciTech Connect

    Bailey, James L.; Barnes, Laurel A.; Wiedmeyer, Stanley G.; Williamson, Mark A.; Willit, James L.

    2014-07-08

    An electrolytic oxide reduction system according to a non-limiting embodiment of the present invention may include a plurality of anode assemblies and an anode shroud for each of the anode assemblies. The anode shroud may be used to dilute, cool, and/or remove off-gas from the electrolytic oxide reduction system. The anode shroud may include a body portion having a tapered upper section that includes an apex. The body portion may have an inner wall that defines an off-gas collection cavity. A chimney structure may extend from the apex of the upper section and be connected to the off-gas collection cavity of the body portion. The chimney structure may include an inner tube within an outer tube. Accordingly, a sweep gas/cooling gas may be supplied down the annular space between the inner and outer tubes, while the off-gas may be removed through an exit path defined by the inner tube.

  11. Photodegradation of estrone enhanced by dissolved organic matter under simulated sunlight.

    PubMed

    Caupos, Emilie; Mazellier, Patrick; Croue, Jean-Philippe

    2011-05-01

    In the present work the degradation of estrone (E1) a natural estrogenic hormone has been studied under simulated solar irradiation. The photodegradation of E1 has been investigated in the absence and in the presence of 7.7-8.9 mg L(-1) of dissolved organic carbon (DOC), under solar light simulation with irradiance approximating that of the sun. DOC extracts from different origins have been used. Half-lives ranging between 3.9 h and 7.9 h were observed. Results indicated that E1 was photodegraded even in the absence of DOC. The presence of DOC was found to enhance the degradation of E1. Experiments performed with the addition of reactive species scavengers (azide ions and 2-propanol) have shown that these two species play a significant role in the photodegradation. Some experiments have been performed with a DOC previously submitted to solar irradiation. Changes in optical and physico-chemical properties of DOC strongly affect its photoinductive properties, and hence its efficiency on E1 degradation. A part of the study consisted in the investigation of photoproducts structures. Five photoproducts were shown by chromatographic analysis: one arising from direct photolysis and the four others from DOC photoinduced degradation. PMID:21530993

  12. Numerical simulations of aquaculture dissolved waste transport in a coastal embayment

    NASA Astrophysics Data System (ADS)

    Venayagamoorthy, Subhas; Fringer, Oliver; Koseff, Jeffrey; Naylor, Rosamond

    2008-11-01

    The present study focuses on understanding the transport and fate of dissolved wastes from aquaculture pens in near-coastal environments using the hydrodynamics code SUNTANS (Stanford Unstructured Nonhydrostatic Terrain-following Adaptive Navier- Stokes Simulator), which employs unstructured grids to compute flows in the coastal ocean at very high resolution. Simulations of a pollutant concentration field (in time and space) as a function of the local environment (bathymetry, rotation), flow conditions (tides, wind-induced currents and wind stress), and the location of the pens were performed to study their effects on the evolution of the waste plume. The presence of the fish farm pens causes partial blockage of the flow, leading to the deceleration of the approaching flow and formation of downstream wakes. Results of both the near-field area (area within 10 to 20 pen diameters of the fish-pen site) as well as far-field behavior of the pollutant field are presented. These results highlight for the first time the importance of the wake vortex dynamics on the evolution of the near-field plume as well as the rotation of the earth on the far-field plume. The results provide an understanding of the impact of aquaculture fish-pens on coastal water quality.

  13. Granular and Dissolved Polyacrylamide Effects on Erosion and Runoff under Simulated Rainfall.

    PubMed

    Kang, Jihoon; Amoozegar, Aziz; Heitman, Joshua L; McLaughlin, Richard A

    2014-11-01

    Polyacrylamide (PAM) has been demonstrated to reduce erosion under many conditions, but less is known about the effects of its application method on erosion and concentrations in the runoff water. A rainfall simulation study was conducted to evaluate the performance of an excelsior erosion control blanket (cover) and two PAM application methods. The treatments were (i) no cover + no PAM (control), (ii) cover + no PAM, (iii) cover + granular PAM (GPAM), and (iv) cover + dissolved PAM (DPAM) applied to soil packed in wooden runoff boxes. The GPAM or DPAM (500 mg L) was surface-applied at a rate of 30 kg ha 1 d before rainfall simulation. Rainfall was applied at 83 mm h for 50 min and then repeated for another 20 min after a 30-min rest period. Runoff samples were analyzed for volume, turbidity in nephelometric turbidity units (NTU), total suspended solids (TSS), sediment particle size distribution, and PAM concentration. The cover alone reduced turbidity and TSS in runoff by >60% compared with the control (2315 NTU, 2777 mg TSS L). The PAM further reduced turbidity and TSS by >30% regardless of the application method. The median particle diameter of eroded sediments for PAM treatments was seven to nine times that of the control (12.4 μm). Loss of applied PAM in the runoff water (not sediment) was 19% for the GPAM treatment but only 2% for the DPAM treatment. Both GPAM and DPAM were effective at improving groundcover performance, but DPAM resulted in much less PAM loss. PMID:25602214

  14. Effect of soil erosion on dissolved organic carbon redistribution in subtropical red soil under rainfall simulation

    NASA Astrophysics Data System (ADS)

    Ma, Wenming; Li, Zhongwu; Ding, Keyi; Huang, Jinquan; Nie, Xiaodong; Zeng, Guangming; Wang, Shuguang; Liu, Guiping

    2014-12-01

    Water erosion governs soil carbon reserves and distribution across the watershed or ecosystem. The dynamics of dissolved organic carbon (DOC) under water erosion in red agricultural soil is not clear. To determine the effect of tillage management and water erosion on vertical and lateral transportation of soil organic carbon (SOC) and DOC production under distinct rainfall intensities in the hilly red soil region of southern China, a chisel tillage plot with low rainfall intensity (CT-L) and two no-tillage plots with high (NT-H) and low rainfall intensity (NT-L) studies were conducted. Soil samples were collected from 0-5, 5-10, 10-20, and 20-40 cm soil layers from triplicate soil blocks pre- and post-rainfall for determining concentration of SOC and DOC. Runoff samples were collected at every 6 min for determining concentration of DOC and sediments during rainfall simulations on runoff plots (2 m × 5 m) with various intensities. No fertilizer was applied in any plots. Results clearly show that runoff volumes, sediments and SOC entrained with sediment, and laterally mobilized DOC were significantly larger on NT-H compared to other plots, coinciding with changes in rainfall intensity; and the extent of roughness of the plot surface (CT vs. NT) was the variation in runoff DOC concentration. During the simulated rainfall events, DOC exports average 0.76, 0.64, and 0.27 g C m- 2 h- 1; SOC exports average 3.52, 1.08, and 0.07 g m- 2 h- 1 in the NT-H, NT-L, and CT-L soils, respectively. The maximum export of DOC was obtained under a high intensity rainfall plot, which lagged behind maximum runoff volumes, sediments, and SOC losses with sediment. Export of DOC was proportional to SOC content of soil loss. The least DOC losses in surface runoff and SOC losses with sediment were observed in CT-L plots. Vertical DOC mobilization achieved its maximum with low intensity rainfall under CT treatment. The DOC did not accumulate at the soil surface and was distributed mainly in

  15. Boundary integral simulations of dissolving drops in segmented two-phase flows

    NASA Astrophysics Data System (ADS)

    Ramchandran, Arun; Leary, Thomas

    2015-11-01

    Recent years have seen an upsurge in the literature reporting the microfluidic measurement of the kinetics of `fast' gas-liquid reactions by recording the shrinkage of bubbles in segmented flows of these gas-liquid combinations in microfluidic channels. A critical aspect of the data analysis in these experiments is the knowledge of how dissolution influences the velocity field in the liquid slug, and hence, the mass transport characteristics. Unfortunately, there is no literature on this connection for dissolving bubbles. Our research addresses this gap using boundary integral simulations. The effects of the dissolution rate on the film thickness and the inter-drop separation are examined as a function of the capillary number and the viscosity ratio. The results demonstrate that dissolution can enhance the degree of mixing appreciably from one slug to the next. A curious result is that the film thickness and the droplet separation distance can change significantly beyond a critical capillary number, producing flow patterns completely different from those known for the undissolving bubble case. These results will guide the selection of operating regimes that enable convenient interpretation of data from experiments to deduce kinetic constants.

  16. Simulation of Temperature, Nutrients, Biochemical Oxygen Demand, and Dissolved Oxygen in the Catawba River, South Carolina, 1996-97

    USGS Publications Warehouse

    Feaster, Toby D.; Conrads, Paul A.; Guimaraes, Wladmir B.; Sanders, Curtis L., Jr.; Bales, Jerad D.

    2003-01-01

    Time-series plots of dissolved-oxygen concentrations were determined for various simulated hydrologic and point-source loading conditions along a free-flowing section of the Catawba River from Lake Wylie Dam to the headwaters of Fishing Creek Reservoir in South Carolina. The U.S. Geological Survey one-dimensional dynamic-flow model, BRANCH, was used to simulate hydrodynamic data for the Branched Lagrangian Transport Model. Waterquality data were used to calibrate the Branched Lagrangian Transport Model and included concentrations of nutrients, chlorophyll a, and biochemical oxygen demand in water samples collected during two synoptic sampling surveys at 10 sites along the main stem of the Catawba River and at 3 tributaries; and continuous water temperature and dissolved-oxygen concentrations measured at 5 locations along the main stem of the Catawba River. A sensitivity analysis of the simulated dissolved-oxygen concentrations to model coefficients and data inputs indicated that the simulated dissolved-oxygen concentrations were most sensitive to watertemperature boundary data due to the effect of temperature on reaction kinetics and the solubility of dissolved oxygen. Of the model coefficients, the simulated dissolved-oxygen concentration was most sensitive to the biological oxidation rate of nitrite to nitrate. To demonstrate the utility of the Branched Lagrangian Transport Model for the Catawba River, the model was used to simulate several water-quality scenarios to evaluate the effect on the 24-hour mean dissolved-oxygen concentrations at selected sites for August 24, 1996, as simulated during the model calibration period of August 23 27, 1996. The first scenario included three loading conditions of the major effluent discharges along the main stem of the Catawba River (1) current load (as sampled in August 1996); (2) no load (all point-source loads were removed from the main stem of the Catawba River; loads from the main tributaries were not removed); and (3

  17. Effect of dissolved oxygen content on stress corrosion cracking of a cold worked 316L stainless steel in simulated pressurized water reactor primary water environment

    NASA Astrophysics Data System (ADS)

    Zhang, Litao; Wang, Jianqiu

    2014-03-01

    Stress corrosion crack growth tests of a cold worked nuclear grade 316L stainless steel were conducted in simulated pressurized water reactor (PWR) primary water environment containing various dissolved oxygen (DO) contents but no dissolved hydrogen. The crack growth rate (CGR) increased with increasing DO content in the simulated PWR primary water. The fracture surface exhibited typical intergranular stress corrosion cracking (IGSCC) characteristics.

  18. Detailed Design Data Package item 3.9a: Cadmium buildup in off-gas lines

    SciTech Connect

    Perez, J.M.; Buchmiller, W.C.; Anderson, L.D.; Whittington, G.A.

    1996-04-01

    Waste currently stored at the Hanford Reservation in underground double-shell and single-shell tanks is being considered for vitrification and disposal. To achieve this, Hanford is conducting a Hanford Waste Vitrification Plant Technology Development Project melter campaign. In this campaign, a requirement was identified to quantify the amount of cadmium depositing in the off-gas line between the liquid-fed ceramic melter and the submerged bed scrubber. This issue of cadmium volatility was raised due to the limited data on cadmium volatility in HLW vitrification. Prior to the start of slurry processing, the off-gas line sections were removed and inspects. Any pre-existing deposits were removed. Following the melter campaign, the lines were again removed and solids deposits were sampled and the quantity of deposits were estimated. The data presented in this package include chemical analysis of feed, glass, line deposits, in-ling off-gas stream, and SBS condensate samples. Process data includes melter feeding and glass production rates, off- gas flow rate, and plenum and off-gas stream temperatures.

  19. Removal efficiency of silver impregnated filter materials and performance of iodie filters in the off-gas of the Karlsruhe reprocessing plant WAK

    SciTech Connect

    Herrmann, F.J.; Herrmann, B.; Hoeflich, V.

    1997-08-01

    An almost quantitative retention of iodine is required in reprocessing plants. For the iodine removal in the off-gas streams of a reprocessing plant various sorption materials had been tested under realistic conditions in the Karlsruhe reprocessing plant WAK in cooperation with the Karlsruhe research center FZK. The laboratory results achieved with different iodine sorption materials justified long time performance tests in the WAK Plant. Technical iodine filters and sorption materials for measurements of iodine had been tested from 1972 through 1992. This paper gives an overview over the most important results, Extended laboratory, pilot plant, hot cell and plant experiences have been performed concerning the behavior and the distribution of iodine-129 in chemical processing plants. In a conventional reprocessing plant for power reactor fuel, the bulk of iodine-129 and iodine-127 is evolved into the dissolver off-gas. The remainder is dispersed over many aqueous, organic and gaseous process and waste streams of the plant. Iodine filters with silver nitrate impregnated silica were installed in the dissolver off-gas of the Karlsruhe reprocessing plant WAK in 1975 and in two vessel vent systems in 1988. The aim of the Karlsruhe iodine research program was an almost quantitative evolution of the iodine during the dissolution process to remove as much iodine with the solid bed filters as possible. After shut down of the WAK plant in December 1990 the removal efficiency of the iodine filters at low iodine concentrations had been investigated during the following years. 12 refs., 2 figs., 2 tabs.

  20. Impact Of Melter Internal Design On Off-Gas Flammability

    SciTech Connect

    Choi, A. S.; Lee, S. Y.

    2012-05-30

    The purpose of this study was to: (1) identify the more dominant design parameters that can serve as the quantitative measure of how prototypic a given melter is, (2) run the existing DWPF models to simulate the data collected using both DWPF and non-DWPF melter configurations, (3) confirm the validity of the selected design parameters by determining if the agreement between the model predictions and data is reasonably good in light of the design and operating conditions employed in each data set, and (4) run Computational Fluid Dynamics (CFD) simulations to gain new insights into how fluid mixing is affected by the configuration of melter internals and to further apply the new insights to explaining, for example, why the agreement is not good.

  1. Simulation of oil bioremediation in a tidally influenced beach: Spatiotemporal evolution of nutrient and dissolved oxygen

    NASA Astrophysics Data System (ADS)

    Geng, Xiaolong; Pan, Zhong; Boufadel, Michel C.; Ozgokmen, Tamay; Lee, Kenneth; Zhao, Lin

    2016-04-01

    Numerical experiments of oil bioremediation of tidally influenced beach were simulated using the model BIOMARUN. Nutrient and dissolved oxygen were assumed present in a solution applied on the exposed beach face, and the concentration of these amendments was tracked throughout the beach for up to 6 months. It was found that, in comparison to natural attenuation, bioremediation increased the removal efficiency by 76% and 65% for alkanes and aromatics, respectively. Increasing the nutrient concentration in the applied solution did not always enhance biodegradation as oxygen became limiting even when the beach was originally oxygen-rich. Therefore, replenishment of oxygen to oil-contaminated zone was also essential. Stimulation of oil biodegradation was more evident in the upper and midintertidal zone of the beach, and less in the lower intertidal zone. This was due to reduced nutrient and oxygen replenishment, as very little of the amendment solution reached that zone. It was found that under continual application, most of the oil biodegraded within 2 months, while it persisted for 6 months under natural conditions. While the difference in duration suggests minimal long-term effects, there are situations where the beach would need to be cleaned for major ecological functions, such as temporary nesting or feeding for migratory birds. Biochemical retention time map (BRTM) showed that the duration of solution application was dependent upon the stimulated oil biodegradation rate. By contrast, the application rate of the amendment solution was dependent upon the subsurface extent of the oil-contaminated zone. Delivery of nutrient and oxygen into coastal beach involved complex interaction among amendment solution, groundwater, and seawater. Therefore, approaches that ignore the hydrodynamics due to tide are unlikely to provide the optimal solutions for shoreline bioremediation.

  2. A novel isotopic fractionation during dissolved oxygen consumption in mesopelagic waters inferred from observation and model simulation of dissolved oxygen δ18O in open oceanic regions

    NASA Astrophysics Data System (ADS)

    Nakayama, N.; Oka, A.; Gamo, T.

    2012-12-01

    Oxygen isotopic ratio (δ18O) of dissolved oxygen is a useful for bioactive tracer of the subsurface aphotic (mesopelagic) ocean since it varies nonlinearly related to oxygen consumption via stoichiometry of organic matter decomposition. Therefore, along with global circulation model (GCM), observed δ18O and their vertical/geographical distribution can be effectively used to quantitatively determine how marine biological and ocean physical processes contribute to varying dissolved oxygen (DO) concentration in the ocean, in particular mesopelagic zone where pronounced biological activity alters DO concentration significantly. In the central north Pacific Ocean and Indian Ocean, including Arabian Sea, one of the few regions in the open ocean which has oxygen minimum zone (OMZ, a layer with severely depleted DO), vertical profiles of DO and δ18O were observed. These observed data are compared with a GCM simulation in which a constant isotopic fractionation factor of DO by marine biological respiration and a fixed Redfield molar ratio between P and O are assumed. Even in the Arabian Sea OMZ, relationship between DO and δ18O was found to be similar to those observed in other open oceans, indicating that no specific oxygen consumption process occurred in the OMZ. Using the GCM model, we attempted to reproduce the observed overall relationship between DO and δ18O, but it failed when we adopted the previously reported isotopic fractionation factor: Discrepancy became larger when oxygen saturation level decreased, in particular in thermocline water (at 20% oxygen saturation level, modeled δ18O was heavier than observed values by +7‰). Sensitivity simulations with the GCM model revealed that (1) simply changing the intensity of oxygen consumption by respiration/organic matter decomposition nor physical processes (diffusion and/or advection) could explain the observed relationship between DO and δ18O, (2) applying a smaller isotopic fractionation for deep waters

  3. Development And Initial Testing Of Off-Gas Recycle Liquid From The WTP Low Activity Waste Vitrification Process - 14333

    SciTech Connect

    McCabe, Daniel J.; Wilmarth, William R.; Nash, Charles A.; Taylor-Pashow, Kathryn M.; Adamson, Duane J.; Crawford, Charles L.; Morse, Megan M.

    2014-01-07

    The Waste Treatment and Immobilization Plant (WTP) process flow was designed to pre-treat feed from the Hanford tank farms, separate it into a High Level Waste (HLW) and Low Activity Waste (LAW) fraction and vitrify each fraction in separate facilities. Vitrification of the waste generates an aqueous condensate stream from the off-gas processes. This stream originates from two off-gas treatment unit operations, the Submerged Bed Scrubber (SBS) and the Wet Electrospray Precipitator (WESP). Currently, the baseline plan for disposition of the stream from the LAW melter is to recycle it to the Pretreatment facility where it gets evaporated and processed into the LAW melter again. If the Pretreatment facility is not available, the baseline disposition pathway is not viable. Additionally, some components in the stream are volatile at melter temperatures, thereby accumulating to high concentrations in the scrubbed stream. It would be highly beneficial to divert this stream to an alternate disposition path to alleviate the close-coupled operation of the LAW vitrification and Pretreatment facilities, and to improve long-term throughput and efficiency of the WTP system. In order to determine an alternate disposition path for the LAW SBS/WESP Recycle stream, a range of options are being studied. A simulant of the LAW Off-Gas Condensate was developed, based on the projected composition of this stream, and comparison with pilot-scale testing. The primary radionuclide that vaporizes and accumulates in the stream is Tc-99, but small amounts of several other radionuclides are also projected to be present in this stream. The processes being investigated for managing this stream includes evaporation and radionuclide removal via precipitation and adsorption. During evaporation, it is of interest to investigate the formation of insoluble solids to avoid scaling and plugging of equipment. Key parameters for radionuclide removal include identifying effective precipitation or ion

  4. Development of density plumes of dissolved CO2: Comparing experimental observations with numerical simulations

    NASA Astrophysics Data System (ADS)

    Kirk, Karen; Vosper, Hayley; Rochelle, Chris; Noy, Dave; Chadwick, Andy

    2014-05-01

    The long-term trapping of CO2 within deep geological storage reservoirs will be dependent upon CO2-water-rock geochemical reactions. The first, and most important, steps in this process will be dissolution of CO2 into the reservoir porewater and the transport of this dissolved CO2 through the reservoir. As part of the CO2CARE project we have investigated these via laboratory tests using a water-filled porous medium. Key experimental parameters were measured to determine system permeability, so that a high-resolution numerical model could be built in an attempt to reproduce the observed system behaviour. The Hele-Shaw cell comprised two glass sheets 65 cm wide and 36 cm high, separated by a spacing of 1.1 mm, and filled with closely-packed glass beads 0.4-0.6 mm in diameter. The surface of the glass was treated to prevent the formation of a higher permeability zone along this interface. A pH-sensitive dye was added to the pore-filling water to show where it had been acidified due to the presence of CO2. CO2 gas was introduced to a space at the top of the cell, which created a thin, diffusion-controlled boundary layer of CO2-rich water below the CO2-water interface. CO2 dissolution increased water density, resulting in gravitational instabilities and the formation of many small, downward-migrating plumes. Time-lapse photography was used to track the formation and progress of these plumes. As the plumes grew they increased in length relative to their width, and decreased in number over time. They also became more complex with time, splitting and forming several lobes, whose outer edges became more diffuse as they mixed with the CO2-poor water. The onset time of plume development and the horizontal wavelength (spacing) of the descending plumes are diagnostic measures of the system properties, notably permeability. They were analysed from the time-lapse images and expressed as probability density functions based on histograms of the observations. The derived

  5. Particulate Scrubbing Performance of the High Level Caves Off-Gas System

    SciTech Connect

    Wright, G.T.

    2001-08-16

    Performance tests were conducted at the ETF using off-gas from the Small Cylindrical Melter (SCM) -2. The purpose of these tests was to develop data for comparing small and full scale equipment performance. This reports discusses those test results.

  6. Cyclonic incineration of low heating-value off-gas. Technology spotlight report

    SciTech Connect

    1995-08-01

    Institute of Gas Technology (IGT) investigated the combustion characteristics of low-Btu off-gas and the operating performance of a pilot-scale cyclonic combustor to evaluate the incineration and heat recovery potential. The successful results suggested, among other things, that the cyclonic combustion approach has good potential for developing an advanced, highly efficient afterburner design for a variety of incinerators.

  7. Removal of I, Rn, Xe and Kr from off gas streams using PTFE membranes

    DOEpatents

    Siemer, Darryl D.; Lewis, Leroy C.

    1990-08-07

    A process for removing I, R, Xe and Kr which involves the passage of the off gas stream through a tube-in-shell assembly, whereby the tubing is a PTFE membrane which permits the selective passages of the gases for removing and isolating the gases.

  8. Removal of I, Rn, Xe and Kr from off gas streams using PTFE membranes

    DOEpatents

    Siemer, Darryl D.; Lewis, Leroy C.

    1990-01-01

    A process for removing I, R, Xe and Kr which involves the passage of the off gas stream through a tube-in-shell assembly, whereby the tubing is a PTFE membrane which permits the selective passages of the gases for removing and isolating the gases.

  9. Preliminary Results from Electric Arc Furnace Off-Gas Enthalpy Modeling

    SciTech Connect

    Nimbalkar, Sachin U; Thekdi, Arvind; Keiser, James R; Storey, John Morse

    2015-01-01

    This article describes electric arc furnace (EAF) off-gas enthalpy models developed at Oak Ridge National Laboratory (ORNL) to calculate overall heat availability (sensible and chemical enthalpy) and recoverable heat values (steam or power generation potential) for existing EAF operations and to test ORNL s new EAF waste heat recovery (WHR) concepts. ORNL s new EAF WHR concepts are: Regenerative Drop-out Box System and Fluidized Bed System. The two EAF off-gas enthalpy models described in this paper are: 1.Overall Waste Heat Recovery Model that calculates total heat availability in off-gases of existing EAF operations 2.Regenerative Drop-out Box System Model in which hot EAF off-gases alternately pass through one of two refractory heat sinks that store heat and then transfer it to another gaseous medium These models calculate the sensible and chemical enthalpy of EAF off-gases based on the off-gas chemical composition, temperature, and mass flow rate during tap to tap time, and variations in those parameters in terms of actual values over time. The models provide heat transfer analysis for the aforementioned concepts to confirm the overall system and major component sizing (preliminary) to assess the practicality of the systems. Real-time EAF off-gas composition (e.g., CO, CO2, H2, and H2O), volume flow, and temperature data from one EAF operation was used to test the validity and accuracy of the modeling work. The EAF off-gas data was used to calculate the sensible and chemical enthalpy of the EAF off-gases to generate steam and power. The article provides detailed results from the modeling work that are important to the success of ORNL s EAF WHR project. The EAF WHR project aims to develop and test new concepts and materials that allow cost-effective recovery of sensible and chemical heat from high-temperature gases discharged from EAFs.

  10. Ambient conditions and fate and transport simulations of dissolved solids, chloride, and sulfate in Beaver Lake, Arkansas, 2006--10

    USGS Publications Warehouse

    Green, W. Reed

    2013-01-01

    Beaver Lake is a large, deep-storage reservoir located in the upper White River Basin in northwestern Arkansas, and was completed in 1963 for the purposes of flood control, hydroelectric power, and water supply. Beaver Lake is affected by point and nonpoint sources of minerals, nutrients, and sediments. The City of Fayetteville discharges about half of its sewage effluent into the White River immediately upstream from the backwater of the reservoir. The City of West Fork discharges its sewage effluent into the West Fork of the White River, and the City of Huntsville discharges its sewage effluent into a tributary of War Eagle Creek. A study was conducted to describe the ambient conditions and fate and transport of dissolved solids, chloride, and sulfate concentrations in Beaver Lake. Dissolved solids, chloride, and sulfate are components of wastewater discharged into Beaver Lake and a major concern of the drinking water utilities that use Beaver Lake as their source. A two-dimensional model of hydrodynamics and water quality was calibrated to include simulations of dissolved solids, chloride, and sulfate for the period January 2006 through December 2010. Estimated daily dissolved solids, chloride, and sulfate loads were increased in the White River and War Eagle Creek tributaries, individually and the two tributaries together, by 1.2, 1.5, 2.0, 5.0, and 10.0 times the baseline conditions to examine fate and transport of these constituents through time at seven locations (segments) in the reservoir, from upstream to downstream in Beaver Lake. Fifteen dissolved solids, chloride, and sulfate fate and transport scenarios were compared to the baseline simulation at each of the seven downstream locations in the reservoir, both 2 meters (m) below the surface and 2 m above the bottom. Concentrations were greater in the reservoir at model segments closer to where the tributaries entered the reservoir. Concentrations resulting from the increase in loading became more diluted

  11. Selective Recovery of Radioactive Carbon Dioxide Released from Nuclear Off-gas by Adsorption

    NASA Astrophysics Data System (ADS)

    Munakata, Kenzo; Koga, Akinori

    Off gases produced in the reprocessing of spent nuclear fuel contain various radioactive gases and emission of these gases to the environment must be suppressed as low as possible. 14C with a long half-life, which is mainly released as the form of carbon dioxide, is one of such gaseous radioactive materials. One of the measures to capture radioactive gases from the off-gas is the utilization of adsorption technique. In this work, the adsorption behavior of carbon dioxide on various adsorbents was studied. It was found that a MS4A (Molecular Sieve 4A) adsorbent is more suitable for selective recovery of carbon dioxide. Thus, more detailed adsorption characteristics of carbon dioxide were studied for a MS4A adsorbent. Moreover, the authors investigated the influence of coexistent water vapor, which is also contained in the off-gas, on the adsorption behavior of carbon dioxide.

  12. Effects of headspace and oxygen level on off-gas emissions from wood pellets in storage.

    PubMed

    Kuang, Xingya; Shankar, Tumuluru Jaya; Sokhansanj, Shahab; Lim, C Jim; Bi, Xiaotao T; Melin, Staffan

    2009-11-01

    Few papers have been published in the open literature on the emissions from biomass fuels, including wood pellets, during the storage and transportation and their potential health impacts. The purpose of this study is to provide data on the concentrations, emission factors, and emission rate factors of CO(2), CO, and CH(4) from wood pellets stored with different headspace to container volume ratios with different initial oxygen levels, in order to develop methods to reduce the toxic off-gas emissions and accumulation in storage spaces. Metal containers (45 l, 305 mm diameter by 610 mm long) were used to study the effect of headspace and oxygen levels on the off-gas emissions from wood pellets. Concentrations of CO(2), CO, and CH(4) in the headspace were measured using a gas chromatograph as a function of storage time. The results showed that the ratio of the headspace ratios and initial oxygen levels in the storage space significantly affected the off-gas emissions from wood pellets stored in a sealed container. Higher peak emission factors and higher emission rates are associated with higher headspace ratios. Lower emissions of CO(2) and CO were generated at room temperature under lower oxygen levels, whereas CH(4) emission is insensitive to the oxygen level. Replacing oxygen with inert gases in the storage space is thus a potentially effective method to reduce the biomass degradation and toxic off-gas emissions. The proper ventilation of the storage space can also be used to maintain a high oxygen level and low concentrations of toxic off-gassing compounds in the storage space, which is especially useful during the loading and unloading operations to control the hazards associated with the storage and transportation of wood pellets. PMID:19805393

  13. The integrated melter off-gas treatment systems at the West Valley Demonstration Project

    SciTech Connect

    Vance, R.F.

    1991-12-01

    The West Valley Demonstration project was established by an act of Congress in 1980 to solidify the high level radioactive liquid wastes produced from operation of the Western New York Nuclear Services Center from 1966 to 1972. The waste will be solidified as borosilicate glass. This report describes the functions, the controlling design criteria, and the resulting design of the melter off-gas treatment systems.

  14. On The Impact of Borescope Camera Air Purge on DWPF Melter Off-Gas Flammability

    SciTech Connect

    CHOI, ALEXANDER

    2004-07-22

    DWPF Engineering personnel requested that a new minimum backup film cooler air flow rate, which will meet the off-gas safety basis limits for both normal and seismic sludge-only operations, be calculated when the air purge to the borescope cameras is isolated from the melter. Specifically, it was requested that the latest calculations which were used to set the off-gas flammability safety bases for the sludge batch 2 and 3 feeds be revised, while maintaining all other process variables affecting off-gas flammability such as total organic carbon (TOC), feed rate, melter air purges, and vapor space temperature at their current respective maximum or minimum limits. Before attempting to calculate the new minimum backup film cooler air flow, some of the key elements of the combustion model were reviewed, and it was determined that the current minimum backup film cooler air flow of 233 lb/hr is adequate to satisfy the off-gas flammability safety bases for both normal and seismic operations i n the absence of any borescope camera air purge. It is, therefore, concluded that there is no need to revise the reference E-7 calculations. This conclusion is in essence based on the fact that the current minimum backup film cooler air flow was set to satisfy the minimum combustion air requirement under the worst-case operating scenario involving a design basis earthquake during which all the air purges not only to the borescope cameras but to the seal pot are presumed to be lost due to pipe ruptures. The minimum combustion air purge is currently set at 150 per cent of the stoichiometric air flow required to combust 3 times the normal flow of flammable gases. The DWPF control strategy has been that 100 per cent of the required minimum combustion air is to be provided by the controlled air purge through the backup film cooler alone.

  15. Effects of Headspace and Oxygen Level on Off-gas Emissions from Wood Pellets in Storage

    SciTech Connect

    Sokhansanj, Shahabaddine; Kuang, Xingya; Shankar, T.S.; Lim, C. Jim; Bi, X.T.; Melin, Staffan

    2009-10-01

    Few papers have been published in the open literature on the emissions from biomass fuels, including wood pellets, during the storage and transportation and their potential health impacts. The purpose of this study is to provide data on the concentrations, emission factors, and emission rate factors of CO2, CO, and CH4 from wood pellets stored with different headspace to container volume ratios with different initial oxygen levels, in order to develop methods to reduce the toxic off-gas emissions and accumulation in storage spaces. Metal containers (45 l, 305 mm diameter by 610 mm long) were used to study the effect of headspace and oxygen levels on the off-gas emissions from wood pellets. Concentrations of CO2, CO, and CH4 in the headspace were measured using a gas chromatograph as a function of storage time. The results showed that the ratio of the headspace ratios and initial oxygen levels in the storage space significantly affected the off-gas emissions from wood pellets stored in a sealed container. Higher peak emission factors and higher emission rates are associated with higher headspace ratios. Lower emissions of CO2 and CO were generated at room temperature under lower oxygen levels, whereas CH4 emission is insensitive to the oxygen level. Replacing oxygen with inert gases in the storage space is thus a potentially effective method to reduce the biomass degradation and toxic off-gas emissions. The proper ventilation of the storage space can also be used to maintain a high oxygen level and low concentrations of toxic off-gassing compounds in the storage space, which is especially useful during the loading and unloading operations to control the hazards associated with the storage and transportation of wood pellets.

  16. OFF-GAS MERCURY CONTROL USING SULFUR-IMPREGNATED ACTIVATED CARBON – TEST RESULTS

    SciTech Connect

    Nick Soelberg

    2007-05-01

    Several laboratory and pilot-scale tests since the year 2000 have included demonstrations of off-gas mercury control using fixed bed, sulfur-impregnated activated carbon. These demonstrations have included operation of carbon beds with gas streams containing a wide range of mercury and other gas species concentrations representing off-gas from several U.S. Department of Energy (DOE) mixed waste treatment processes including electrical resistance heated (joule-heated) glass melters, fluidized bed calciners, and fluidized bed steam reformers. Surrogates of various DOE mixed waste streams (or surrogates of offgas from DOE mixed waste streams) including INL “sodium bearing waste” (SBW), liquid “low activity waste” (LAW) from the Pacific Northwest National Laboratory, and liquid waste from Savannah River National Laboratory (“Tank 48H waste”) have been tested. Test results demonstrate mercury control efficiencies up to 99.999%, high enough to comply with the Hazardous Waste (HWC) Combustor Maximum Achievable Control Technology (MACT) standards even when the uncontrolled off-gas mercury concentrations exceed 400,000 ug/dscm (at 7% O2), and confirm carbon bed design parameters for such high efficiencies. Results of several different pilot-scale and engineering-scale test programs performed over several years are presented and compared.

  17. Selective Trapping of Volatile Fission Products with an Off-Gas Treatment System

    SciTech Connect

    B.R. Westphal; J.J. Park; J.M. Shin; G.I. Park; K.J. Bateman; D.L. Wahlquist

    2008-07-01

    A head-end processing step, termed DEOX for its emphasis on decladding via oxidation, is being developed for the treatment of spent oxide fuel by pyroprocessing techniques. The head-end step employs high temperatures to oxidize UO2 to U3O8 resulting in the separation of fuel from cladding and the removal of volatile fission products. Development of the head-end step is being performed in collaboration with the Korean Atomic Energy Research Institute (KAERI) through an International Nuclear Energy Research Initiative. Following the initial experimentation for the removal of volatile fission products, an off-gas treatment system was designed in conjunction with KAERI to collect specific fission gases. The primary volatile species targeted for trapping were iodine, technetium, and cesium. Each species is intended to be collected in distinct zones of the off-gas system and within those zones, on individual filters. Separation of the volatile off-gases is achieved thermally as well as chemically given the composition of the filter media. A description of the filter media and a basis for its selection will be given along with the collection mechanisms and design considerations. In addition, results from testing with the off-gas treatment system will be presented.

  18. Advanced Off-Gas Control System Design For Radioactive And Mixed Waste Treatment

    SciTech Connect

    Nick Soelberg

    2005-09-01

    Treatment of radioactive and mixed wastes is often required to destroy or immobilize hazardous constituents, reduce waste volume, and convert the waste to a form suitable for final disposal. These kinds of treatments usually evolve off-gas. Air emission regulations have become increasingly stringent in recent years. Mixed waste thermal treatment in the United States is now generally regulated under the Hazardous Waste Combustor (HWC) Maximum Achievable Control Technology (MACT) standards. These standards impose unprecedented requirements for operation, monitoring and control, and emissions control. Off-gas control technologies and system designs that were satisfactorily proven in mixed waste operation prior to the implementation of new regulatory standards are in some cases no longer suitable in new mixed waste treatment system designs. Some mixed waste treatment facilities have been shut down rather than have excessively restrictive feed rate limits or facility upgrades to comply with the new standards. New mixed waste treatment facilities in the U. S. are being designed to operate in compliance with the HWC MACT standards. Activities have been underway for the past 10 years at the INL and elsewhere to identify, develop, demonstrate, and design technologies for enabling HWC MACT compliance for mixed waste treatment facilities. Some specific off-gas control technologies and system designs have been identified and tested to show that even the stringent HWC MACT standards can be met, while minimizing treatment facility size and cost.

  19. Removal of Mercury from SBW Vitrification Off-Gas by Activated Carbon

    SciTech Connect

    Deldebbio, John Anthony; Watson, T. T.; Kirkham, Robert John

    2001-09-01

    Radioactive, acidic waste stored at the Idaho Nuclear Technology and Engineering Center (INTEC) have been previously converted into a dry, granular solid at the New Waste Calcining Facility (NWCF). As an alternative to calcination, direct vitrification of the waste, as well as the calcined solids in an Idaho Waste Vitrification Facility (IWVF) is being considered to prepare the waste for final disposal in a federal repository. The remaining waste to be processed is Sodium-Bearing Waste (SBW). Off-gas monitoring during NWCF operations have indicated that future mercury emissions may exceed the proposed Maximum Achievable Control Technology (MACT) limit of 130 ug/dscm (micrograms/dry standard cubic meter) @ 7% O2 for existing Hazardous Waste Combustors (HWC) if modifications are not made. Carbon monoxide and hydrocarbon emissions may also exceed the MACT limits. Off-gas models have predicted that mercury levels in the off-gas from SBW vitrification will exceed the proposed MACT limit of 45 ug/dscm @ 7% O2 for new HWCs. NO2/44% H2O.

  20. Characterization and Dessolution Test results for the January 2005 DWPF Off Gas Condensate Tank Samples (U)

    SciTech Connect

    Fellinger, T

    2005-04-08

    The Off Gas Condensate Tank (OGCT) at the Defense Waste Processing Facility (DWPF) collects the condensate from the off-gas system of the melter. The condensate stream contains entrained solids that collect in the OGCT. Water from the OGCT is re-circulated to the Steam Atomized Scrubber and quencher and may provide a mechanism for re-introducing the particulates into the off-gas system. These particulates are thought to be responsible for plugging the downstream High Efficiency Mist Eliminator filters. Therefore, the OGCT needs to be periodically cleaned to remove the build-up of entrained solids. Currently, the OGCT is cleaned by adding nominally 12 wt% nitric acid with agitation to slurry the solids from the tank. Samples from the OGCT were sent to the Savannah River National Lab (SRNL) for characterization and to conduct tests to determine the optimum nitric acid concentration and residence time to allow more effective cleaning of the OGCT. This report summarizes the chemical and radionuclide results and the results from the nitric acid dissolution testing at 50% and 12% obtained for the OGCT sample.

  1. Theory to boil-off gas cooled shields for cryogenic storage vessels

    NASA Astrophysics Data System (ADS)

    Hofmann, A.

    2004-03-01

    An intermediate refrigeration with boil-off gas cooled shields using the boil-off gas stream is an alternative method to the conventional intermediate refrigeration with a cryogenic liquid. By using an analytical calculation method relations are derived, which enable complete predictions about the effectiveness of an intermediate refrigeration with boil-off gas cooled shields as a function of the number of shields for the different stored cryogenic liquids. For this theoretical derivation however, the restrictive assumption must be made that the thermal conductivity of the used insulation material has a constant value between the considered temperature boundaries. For purposes of a more exact calculation a numerical method is therefore suggested, which takes into consideration that the thermal conductivity is temperature-dependent. For a liquid hydrogen storage vessel with a perlite-vacuum insulation e.g., the effectiveness of one shield and its equilibrium temperature are given as a function of the position of the shield in the insulation space.

  2. Characterization of water quality and simulation of temperature, nutrients, biochemical oxygen demand, and dissolved oxygen in the Wateree River, South Carolina, 1996-98

    USGS Publications Warehouse

    Feaster, Toby D.; Conrads, Paul A.

    2000-01-01

    In May 1996, the U.S. Geological Survey entered into a cooperative agreement with the Kershaw County Water and Sewer Authority to characterize and simulate the water quality in the Wateree River, South Carolina. Longitudinal profiling of dissolved-oxygen concentrations during the spring and summer of 1996 revealed dissolved-oxygen minimums occurring upstream from the point-source discharges. The mean dissolved-oxygen decrease upstream from the effluent discharges was 2.0 milligrams per liter, and the decrease downstream from the effluent discharges was 0.2 milligram per liter. Several theories were investigated to obtain an improved understanding of the dissolved-oxygen dynamics in the upper Wateree River. Data suggest that the dissolved-oxygen concentration decrease is associated with elevated levels of oxygen-consuming nutrients and metals that are flowing into the Wateree River from Lake Wateree. Analysis of long-term streamflow and water-quality data collected at two U.S. Geological Survey gaging stations suggests that no strong correlation exists between streamflow and dissolved-oxygen concentrations in the Wateree River. However, a strong negative correlation does exist between dissolved-oxygen concentrations and water temperature. Analysis of data from six South Carolina Department of Health and Environmental Control monitoring stations for 1980.95 revealed decreasing trends in ammonia nitrogen at all stations where data were available and decreasing trends in 5-day biochemical oxygen demand at three river stations. The influence of various hydrologic and point-source loading conditions on dissolved-oxygen concentrations in the Wateree River were determined by using results from water-quality simulations by the Branched Lagrangian Transport Model. The effects of five tributaries and four point-source discharges were included in the model. Data collected during two synoptic water-quality samplings on June 23.25 and August 11.13, 1997, were used to calibrate

  3. Formation rate of ammonium nitrate in the off-gas line of SRAT and SME in DWPF

    SciTech Connect

    Lee, L.

    1992-02-25

    A mathematical model for the formation rate of ammonium nitrate in the off-gas line of the Sludge Receipt and Adjustment Tank (SRAT) and the Slurry Mixed Evaporator (SME) in DWPF has been developed. The formation rate of ammonium nitrate in the off-gas line depends on pH, temperature, volume and total concentration of ammonia and ammonium ion. Based on a typical SRAT and SME cycle in DWPF, this model predicts the SRAT contributes about 50 lbs of ammonium nitrate while SME contributes about 60 lbs of ammonium nitrate to the off-gas line.

  4. Off-gas chemistry study of melter feed by Springborn Laboratories. [Sludge-only and sludge-precipitate feed samples

    SciTech Connect

    Crow, K.R.

    1985-06-05

    The purpose of the off-gas chemistry study of melter feed samples was to support and help substantiate glass melter thermochemistry models developed for the DWPF. Both sludge-only and sludge-precipitate feed samples were analyzed. Each slurry sample was pyrolyzed at temperatures from 150 to 1000/sup 0/C in air and inert atmospheres, and the head space products were analyzed by chromatographic and mass spectrometric methods. Thermogravimetric, differential scanning calorimetric and Fourier transform infrared analyses were also performed on each sample. There were no unusually high exothermic reactions that would be cause for concern in the DWPF melter. Results for two types of sludge-precipitate feed were compared. One type contained simulated precipitate hydrolysis aqueous (PHA) product as fed to the SCM-2 melter. The second type contained PHA from the lab-scale acid hydrolysis reactor in 677-T. A major difference between the two types was a small, but distinct, presence of higher aromatics in gas from feed with reactor-produced PHA. This feed also evolved more CO and CO/sub 2/ than feed with simulated PHA at high pyrolytic temperatures (>750/sup 0/C). Recent analyses have identified the higher boiling aromatics in reactor-produced PHA as primarily diphenylamine and p-terphenyl. These compounds will be included in future PHA simulations that are fed to research melters. Under an inert atmosphere, benzene and phenol were the two most abundant organics evolved during pyrolysis of sludge-precipitate feed.

  5. Simulation modeling of hydropower impacts on dissolved oxygen in the upper Ohio river basin

    SciTech Connect

    Railsback, S.F.; Jager, H.I.

    1988-09-01

    A model has been developed to assess the impacts of hydropower development at navigation dams on dissolved oxygen (DO) concentrations in the upper Ohio River basin. Field data were used to fit statistical models of aeration at each dam. The Streeter-Phelps equations were used to model DO concentrations between dams. Input data sources were compiled, and the design conditions used for assessment of hydropower impacts were developed. The model was implemented both as Lotus 1-2-3 spreadsheets and as a FORTRAN program. This report contains users' guides for both of these implementations. The sensitivities and uncertainty of the model were analyzed. Modeled DO concentrations are sensitive to water temperature and flow rates, and sensitivities to dam aeration are relatively high in reaches where dam aeration rates are high. Uncertainty in the model was low in reaches dominated by dam aeration and higher in reaches with low dam aeration rates. The 95% confidence intervals for the model range from about /+-/ 0.5 mg/L to about /+-/ 1.5 mg/L.

  6. Utilization of heat of off-gas from regeneration of cracking catalysts

    SciTech Connect

    Golomshtok, L.I.; Bogdanov, A.I.; Kolomiitsev, Y.V.; Levashova, T.M.; Levitskii, E.A.; Zen'kovskii, S.M.

    1983-07-01

    Shortcomings of boiler-utilizer of the convective type, for the utilization of the physical heat of off-gas, have encouraged the development of the afterburner, a reactor with a fluidized bed of an oxidation catalyst, to replace the boiler-utilizer. Catalysts are investigated and copper chromite or chromium oxide are found sufficient. A test-stand evaluation of the process will precede a full scale experimental test, the results of which will formulate guidelines for the development of the carbon monoxide afterburner.

  7. Critique of Hanford Waste Vitrification Plant off-gas sampling requirements

    SciTech Connect

    Goles, R.W.

    1996-03-01

    Off-gas sampling and monitoring activities needed to support operations safety, process control, waste form qualification, and environmental protection requirements of the Hanford Waste Vitrification Plant (HWVP) have been evaluated. The locations of necessary sampling sites have been identified on the basis of plant requirements, and the applicability of Defense Waste Processing Facility (DWPF) reference sampling equipment to these HWVP requirements has been assessed for all sampling sites. Equipment deficiencies, if present, have been described and the bases for modifications and/or alternative approaches have been developed.

  8. FY-12 INL KR CAPTURE ACTIVITIES SUPPORTING THE OFF-GAS SIGMA TEAM

    SciTech Connect

    Troy G. Garn; Mitchell R. Greenhalgh; Jack D Law

    2012-08-01

    Tasks performed this year by INL Kr capture off-gas team members can be segregated into three separate task sub-sections which include: 1) The development and testing of a new engineered form sorbent, 2) An initial NDA gamma scan effort performed on the drum containing the Legacy Kr-85 sample materials, and 3) Collaborative research efforts with PNNL involving the testing of the Ni-DOBDC MOF and an initial attempt to make powdered chalcogel material into an engineered form using our binding process. This document describes the routes to success for the three task sub-sections.

  9. CHARACTERIZATION OF DWPF MELTER OFF-GAS QUENCHER AND STEAM ATOMIZED SCRUBBER DEPOSIT SAMPLES

    SciTech Connect

    Zeigler, K; Ned Bibler, N

    2007-06-06

    This report summarizes the results from the characterization of deposits from the inlets of the primary off-gas Quencher and Steam Atomized Scrubber (SAS) in the Defense Waste Processing Facility (DWPF), as requested by a technical assistance request. DWPF requested elemental analysis and compound identification to help determine the potential causes for the substance formation. This information will be fed into Savannah River National Laboratory modeling programs to determine if there is a way to decrease the formation of the deposits. The general approach to the characterization of these samples included x-ray diffraction (XRD), scanning electron microscopy (SEM), and chemical analysis. The following conclusions are drawn from the analytical results found in this report: (1) The deposits are not high level waste glass from the DWPF melt pool based on comparison of the compositions of deposits to the composition of a sample of glass taken from the pour stream of the melter during processing of Sludge Batch 3. (2) Chemical composition results suggest that the deposits are probably a combination of sludge and frit particles entrained in the off-gas. (3) Gamma emitters, such as Co-60, Cs-137, Eu-154, Am-241, and Am-243 were detected in both the Quencher and SAS samples with Cs-137 having the highest concentration of the gamma emitters. (4) No evidence existed for accumulation of fissile material (U-233, U-235, and Pu-239) relative to Fe in either deposit. (5) XRD results indicated both samples were primarily amorphorous and contained some crystals of the iron oxides, hematite and magnetite (Fe{sub 2}O{sub 3} and Fe(Fe{sub 2}O{sub 4})), along with sodium nitrate (NaNO{sub 3}). The other main crystalline compound in the SAS deposit was mercurous chloride. The main crystalline compound in the Quencher deposit was a uranium oxide compound. These are all sludge components. (6) SEM analysis of the Quencher deposit revealed crystalline uranium compounds within the sample

  10. Analysis and numerical simulation of natural and human-caused low dissolved oxygen in the Minjiang River Estuary.

    PubMed

    Zhang, Peng; Pang, Yong; Shi, Chengchun; Wang, Yishu; Xu, Lei; Pan, Hongche; Xie, Rongrong

    2016-01-01

    The Minjiang River, a typical tidal channel in Southeast China, plays an important role in the supply of drinking water, flood control and drought relief, farming and navigation, as well as shipping and other functions. Dissolved oxygen (DO), as a basic living condition for aquatic biota, has been deteriorating in the Minjiang River in recent years. In order to understand how the spatial distribution of DO responds to river discharge, nutrient loading and water temperature, a three-dimensional Environmental Fluid Dynamics Code model was used to simulate water age and the distribution of DO in the Minjiang River. The model presented in this paper was used for water resource and water quality simulations under various physical, chemical, and biological scenarios. Sensitivity simulation results indicated that the three factors had a significant impact on the spatial distribution variation of DO in the Minjiang River. Increased river discharge or split ratio of the North Channel resulted in decreased water age and increased DO. Increased nutrient loading and water temperature caused lower DO. In order to protect coastal environments in the Minjiang River, river discharge should be increased and pollutants of local cities should be reduced during the high temperature and drought period. PMID:27191570

  11. Recovery Act: Molecular Simulation of Dissolved Inorganic Carbons for Underground Brine CO2 Sequestration

    SciTech Connect

    Goddard, William

    2012-11-30

    To further our understanding and develop the method for measuring the DICs under geological sequestration conditions, we studied the infrared spectra of DICs under high pressure and temperature conditions. First principles simulations of DICs in brine conditions were performed using a highly optimized ReaxFF-DIC forcefield. The thermodynamics stability of each species were determined using the 2PT method, and shown to be consistent with the Reax simulations. More importantly, we have presented the IR spectra of DIC in real brine conditions as a function of temperature and pressure. At near earth conditions, we find a breaking of the O-C-O bending modes into asymmetric and symmetric modes, separated by 100cm{sup -1} at 400K and 5 GPa. These results can now be used to calibrate FTIR laser measurements.

  12. Literature review: Assessment of DWPF melter and melter off-gas system lifetime

    SciTech Connect

    Reigel, M. M.

    2015-07-30

    A glass melter for use in processing radioactive waste is a challenging environment for the materials of construction (MOC) resulting from a combination of high temperatures, chemical attack, and erosion/corrosion; therefore, highly engineered materials must be selected for this application. The focus of this report is to review the testing and evaluations used in the selection of the Defense Waste Processing Facility (DWPF), glass contact MOC specifically the Monofrax® K-3 refractory and Inconel® 690 alloy. The degradation or corrosion mechanisms of these materials during pilot scale testing and in-service operation were analyzed over a range of oxidizing and reducing flowsheets; however, DWPF has primarily processed a reducing flowsheet (i.e., Fe2+/ΣFe of 0.09 to 0.33) since the start of radioactive operations. This report also discusses the materials selection for the DWPF off-gas system and the corrosion evaluation of these materials during pilot scale testing and non-radioactive operations of DWPF Melter #1. Inspection of the off-gas components has not been performed during radioactive operations with the exception of maintenance because of plugging.

  13. Literature review: Assessment of DWPF melter and melter off-gas system lifetime

    SciTech Connect

    Reigel, M.

    2015-07-30

    A glass melter for use in processing radioactive waste is a challenging environment for the materials of construction (MOC) resulting from a combination of high temperatures, chemical attack, and erosion/corrosion; therefore, highly engineered materials must be selected for this application. The focus of this report is to review the testing and evaluations used in the selection of the Defense Waste Processing Facility (DWPF), glass contact MOC specifically the Monofrax® K-3 refractory and Inconel® 690 alloy. The degradation or corrosion mechanisms of these materials during pilot scale testing and in-service operation were analyzed over a range of oxidizing and reducing flowsheets; however, DWPF has primarily processed a reducing flowsheet (i.e., Fe2+/ΣFe of 0.09 to 0.33) since the start of radioactive operations. This report also discusses the materials selection for the DWPF off-gas system and the corrosion evaluation of these materials during pilot scale testing and non-radioactive operations of DWPF Melter #1. Inspection of the off-gas components has not been performed during radioactive operations with the exception of maintenance because of plugging.

  14. Respiratory response to formaldehyde and off-gas of urea formaldehyde foam insulation.

    PubMed Central

    Day, J H; Lees, R E; Clark, R H; Pattee, P L

    1984-01-01

    In 18 subjects, 9 of whom had previously complained of various nonrespiratory adverse effects from the urea formaldehyde foam insulation (UFFI) in their homes, pulmonary function was assessed before and after exposure in a laboratory. On separate occasions formaldehyde, 1 part per million (ppm), and UFFI off-gas yielding a formaldehyde concentration of 1.2 ppm, were delivered to each subject in an environmental chamber for 90 minutes and a fume hood for 30 minutes respectively. None of the measures of pulmonary function used (forced vital capacity, forced expiratory volume in 1 second or maximal midexpiratory flow rate) showed any clinically or statistically significant response to the exposure either immediately after or 8 hours after its beginning. There were no statistically significant differences between the responses of the group that had previously complained of adverse effects and of the group that had not. There was no evidence that either formaldehyde or UFFI off-gas operates as a lower airway allergen or important bronchospastic irritant in this heterogeneous population. Images Fig. 1 PMID:6388780

  15. Assessment of the impact of TOA partitioning on DWPF off-gas flammability

    SciTech Connect

    Daniel, W. E.

    2013-06-01

    An assessment has been made to evaluate the impact on the DWPF melter off-gas flammability of increasing the amount of TOA in the current solvent used in the Modular Caustic-Side Solvent Extraction Process Unit (MCU) process. The results of this study showed that the concentrations of nonvolatile carbon of the current solvent limit (150 ppm) in the Slurry Mix Evaporator (SME) product would be about 7% higher and the nonvolatile hydrogen would be 2% higher than the actual current solvent (126 ppm) with an addition of up to 3 ppm of TOA when the concentration of Isopar L in the effluent transfer is controlled below 87 ppm and the volume of MCU effluent transfer to DWPF is limited to 15,000 gallons per Sludge Receipt and Adjustment Tank (SRAT)/SME cycle. Therefore, the DWPF melter off-gas flammability assessment is conservative for up to an additional 3 ppm of TOA in the effluent based on these assumptions. This report documents the calculations performed to reach this conclusion.

  16. Method of measurement of VOCs in the off-gas and wastewater of wastewater treatment plants

    SciTech Connect

    Min Wang; Keener, T.C.; Orton, T.L.; Zhu, H.; Bishop, P.; Pekonen, S.; Siddiqui, K.

    1997-12-31

    VOCs need to be controlled according to Title 3 of the 1990 Clean Air Act Amendments (CAAA), so an accurate estimation of the total VOC emissions must be attained. This paper reports on a study where EPA method 624 was revised so that this method could be used for VOC analysis both in the water and off-gas of wastewater treatment plants. The revised method uses the same approach and equipment as water and soil analyses, thereby providing a great time and cost advantage for anyone needing to perform this type of analysis. Without using a cryogenic preconcentration step, gas samples from Tedlar bags are easily analyzed to concentrations of approximately 20 ppb using scan mode in a GC-MS unit. For the wastewater, scan mode was still used for the identification, but Selected Ion Monitoring (SIM) mode was used for quantitative analysis because of lower VOC concentration in the water. The results show that this method`s detection limit (MDL) was lowered 2--3 orders of magnitude when compared with scan mode. The modified method has been successfully applied to the identification and quantitative analysis of wastewater and off-gas VOCs from a publicly owned treatment works (POTW) aeration basin (120 MGD).

  17. Cr(VI) Generation During Flaring of CO-Rich Off-Gas from Closed Ferrochromium Submerged Arc Furnaces

    NASA Astrophysics Data System (ADS)

    du Preez, S. P.; Beukes, J. P.; van Zyl, P. G.

    2015-04-01

    Ferrochromium (FeCr) is the only source of new Cr units used in stainless steel production, which is a vital modern day alloy, making FeCr equally important. Small amounts of Cr(VI) are unintentionally formed during several FeCr production steps. One such production step is the flaring of CO-rich off-gas from closed submerged arc furnaces (SAF), for which Cr(VI) formation is currently not quantified. In this study, the influence of flaring temperature, size of the particles passing through the flare, and retention time within the flame were investigated by simulating the process on laboratory scale with a vertical tube furnace. Multiple linear regression (MLR) analysis was conducted on the overall dataset obtained, which indicated that retention time had the greatest impact on pct Cr(VI) conversion, followed by particle size and temperature. The MLR analysis also yielded an optimum mathematical solution, which could be used to determine the overall impact of these parameters on pct Cr(VI) conversion. This equation was used to determine realistic and unrealistic worst-case scenario pct Cr(VI) conversions for actual FeCr SAFs, which yielded 2.7 × 10-2 and 3.5 × 10-1 pct, respectively. These values are significantly lower than the current unsubstantiated pct Cr(VI) conversion used in environmental impact assessments for FeCr smelters, i.e., 0.8 to 1 pct.

  18. Dissolved gas - the hidden saboteur

    SciTech Connect

    Magorien, V.G.

    1993-12-31

    Almost all hydraulic power components, to properly perform their tasks, rely on one basic, physical property, i.e., the incompressibility of the working fluid. Unfortunately, a frequently overlooked fluid property which frustrates this requirement is its ability to absorb, i.e., dissolve, store and give off gas. The gas is, most often but not always, air. This property is a complex one because it is a function not only of the fluid`s chemical make-up but temperature, pressure, exposed area, depth and time. In its relationshiop to aircraft landing-gear, where energy is absorbed hydraulically, this multi-faceted fluid property can be detrimental in two ways: dynamically, i.e., loss of energy absorption ability and statically, i.e., improper aircraft attitude on the ground. The pupose of this paper is to bring an awareness to this property by presenting: (1) examples of these manifestations with some empirical and practical solutions to them, (2) illustrations of this normally `hidden saboteur` at work, (3) Henry`s Dissolved Gas Law, (4) room-temperature, saturated values of dissolved gas for a number of different working fluids, (5) a description of the instrument used to obtain them, (6) some `missing elements` of the Dissolved Gas Law pertaining to absoption, (7) how static and dynamic conditions effect gas absorption and (8) some recommended solutions to prevent becoming a victim of this `hidden saboteur`

  19. Mechanical biological treatment of organic fraction of MSW affected dissolved organic matter evolution in simulated landfill.

    PubMed

    Salati, Silvia; Scaglia, Barbara; di Gregorio, Alessandra; Carrera, Alberto; Adani, Fabrizio

    2013-08-01

    The aim of this paper was to study the evolution of DOM during 1 year of observation in simulated landfill, of aerobically treated vs. untreated organic fraction of MSW. Results obtained indicated that aerobic treatment of organic fraction of MSW permitted getting good biological stability so that, successive incubation under anaerobic condition in landfill allowed biological process to continue getting a strong reduction of soluble organic matter (DOM) that showed, also, an aromatic character. Incubation of untreated waste gave similar trend, but in this case DOM decreasing was only apparent as inhibition of biological process in landfill did not allow replacing degraded/leached DOM with new material coming from hydrolysis of fresh OM. PMID:23743423

  20. Interim report on testing of off-gas treatment technologies for abatement of atmospheric emissions of chlorinated volatile organic compounds

    SciTech Connect

    Haselow, J.S.; Jarosch, T.R.; Rossabi, J.; Burdick, S.; Lombard, K.

    1993-12-01

    The purpose of this report is to briefly summarize the results to date of the off-gas treatment program for atmospheric emissions of chlorinated volatile organic compounds (CVOCs), in particular trichloroethylene (TCE) and perchloroethylene (PCE). This program is part of the Department of Energy`s Office of Technology Development`s Integrated Demonstration for Treatment of Organics in Soil and Water at a Non-Arid Site. The off-gas treatment program was initiated after testing of in-situ air stripping with horizontal wells was completed. That successful test expectedly produced atmospheric emissions of CVOCs that were unabated. It was decided after that test that an off-gas treatment program would complement the Integrated Demonstration not only because off-gas treatment is an integral portion of remediation of CVOC contamination in groundwater and soil but also because several technologies were being developed across the US to mitigate CVOC emissions. A single platform for testing off-gas treatment technologies would facilitate systematic and unbiased evaluation of the emerging technologies.

  1. Study on Indirect Measuring Technology of EAF Steelmaking Decarburization Rate by Off-gas Analysis Technique in Hot State Experiment

    NASA Astrophysics Data System (ADS)

    Dong, Kai; Liu, Wenjuan; Zhu, Rong

    2015-10-01

    In this paper, measurement method of EAF Steelmaking decarburization rate is studied. Because of the fuel gas blown and air mixed, the composition of hot temperature off-gas is measurand unreally, and the flow rate is unknown too, the direct measurement of EAF decarburization rate by furnace gas analysis is unrealized. Firstly, the off-gas generation process is discussed. After that, dynamic concentration of CO2, CO, and O2 in off-gas and EAF oxygen supply rate are monitored in real time. Finally, the concentration and volume flow rate of off-gas are obtained to measure the EAF decarburization rate indirectly. The results of the hot state experiments show that the decarburization rate in oxidization step can reach up to about 0.53 mol/s, and the forecasting carbon concentration is 1.14% corresponding to the average carbon concentration (1.43%) in finial metal samples. The measurement of decarburization rate by off-gas analysis technique can be reasonable in EAF production process.

  2. Risk ranking of bioaccessible metals from fly ash dissolved in simulated lung and gut fluids

    SciTech Connect

    John Twining; Peter McGlinn; Elaine Loi; Kath Smith; Reto Giere

    2005-10-01

    Power plant fly ash from two fuels, coal and a mixture of coal and shredded tires were evaluated for trace metal solubility in simulated human lung and gut fluids (SLF and SGF, respectively) to estimate bioaccessibility. The proportion of bioaccessible to total metal ranged from zero (V) to 80% (Zn) for coal-derived ash in SLF and from 2 (Th) to 100% (Cu) for tire-derived fly ash in SGF. The tire-derived ash contained much more Zn. However, Zn ranked only 5th of the various toxic metals in SGF compared with international regulations for ingestion. On the basis of total concentrations, the metals closest to exceeding limits based on international regulations for inhalation were Cr, Pb, and Al. On dissolution in SLF, the most limiting metals were Pb, Cu, and Zn. For metals exposed to SGF there was no relative change in the top metal, Al, before and after dissolution but the second-ranked metal shifted from Pb to Ni. In most cases only a proportion of the total metal concentrations in either fly ash was soluble, and hence bioaccessible, in either biofluid. When considering the regulatory limits for inhalation of particulates, none of the metal concentrations measured were as hazardous as the fly ash particulates themselves. However, on the basis of the international ingestion regulations for Al, the maximum mass of fly ash that could be ingested is only 1 mg per day (10 mg based on bioaccessibility). It is possible that such a small mass could be consumed by exposed individuals or groups. 39 refs., 1 fig., 3 tabs.

  3. CALCULATION OF DEMONSTRATION BULK VITRIFICATION SYSTEM MELTER INLEAKAGE AND OFF-GAS GENERATION RATE

    SciTech Connect

    MAY TH

    2008-04-16

    The River Protection Project (RPP) mission is to safely store, retrieve, treat, immobilize, and dispose of the Hanford Site tank waste. The Demonstration Bulk Vitrification System (DBVS) is a research and development project whose objective is to demonstrate the suitability of Bulk Vitrification treatment technology waste form for disposing of low-activity waste from the Tank Farms. The objective of this calculation is to determine the DBVS melter inleakage and off-gas generation rate based on full scale testing data from 38D. This calculation estimates the DBVS melter in leakage and gas generation rate based on test data. Inleakage is estimated before the melt was initiated, at one point during the melt, and at the end of the melt. Maximum gas generation rate is also estimated.

  4. MELTER OFF-GAS FLAMMABILITY ASSESSMENT FOR DWPF ALTERNATE REDUCTANT FLOWSHEET OPTIONS

    SciTech Connect

    Choi, A.

    2011-07-08

    Glycolic acid and sugar are being considered as potential candidates to substitute for much of the formic acid currently being added to the Defense Waste Processing Facility (DWPF) melter feed as a reductant. A series of small-scale melter tests were conducted at the Vitreous State Laboratory (VSL) in January 2011 to collect necessary data for the assessment of the impact of these alternate reductants on the melter off-gas flammability. The DM10 melter with a 0.021 m{sup 2} melt surface area was run with three different feeds which were prepared at SRNL based on; (1) the baseline formic/nitric acid flowsheet, (2) glycolic/formic/nitric acid flowsheet, and (3) sugar/formic/nitric acid flowsheet - these feeds will be called the baseline, glycolic, and sugar flowsheet feeds, respectively, hereafter. The actual addition of sugar to the sugar flowsheet feed was made at VSL before it was fed to the melter. For each feed, the DM10 was run under both bubbled (with argon) and non-bubbled conditions at varying melter vapor space temperatures. The goal was to lower its vapor space temperature from nominal 500 C to less than 300 C at 50 C increments and maintain steady state at each temperature at least for one hour, preferentially for two hours, while collecting off-gas data including CO, CO{sub 2}, and H{sub 2} concentrations. Just a few hours into the first test with the baseline feed, it was discovered that the DM10 vapor space temperature would not readily fall below 350 C simply by ramping up the feed rate as the test plan called for. To overcome this, ambient air was introduced directly into the vapor space through a dilution air damper in addition to the natural air inleakage occurring at the operating melter pressure of -1 inch H{sub 2}O. A detailed description of the DM10 run along with all the data taken is given in the report issued by VSL. The SRNL personnel have analyzed the DM10 data and identified 25 steady state periods lasting from 32 to 92 minutes for all

  5. Electrolytic dissolver

    DOEpatents

    Wheelwright, E.J.; Fox, R.D.

    1975-08-26

    This patent related to an electrolytic dissolver wherein dissolution occurs by solution contact including a vessel of electrically insulative material, a fixed first electrode, a movable second electrode, means for insulating the electrodes from the material to be dissolved while permitting a free flow of electrolyte therebetween, means for passing a direct current between the electrodes and means for circulating electrolyte through the dissolver. (auth)

  6. Simulated climate change impact on summer dissolved organic carbon release from peat and surface vegetation: implications for drinking water treatment.

    PubMed

    Ritson, Jonathan P; Bell, Michael; Graham, Nigel J D; Templeton, Michael R; Brazier, Richard E; Verhoef, Anne; Freeman, Chris; Clark, Joanna M

    2014-12-15

    Uncertainty regarding changes in dissolved organic carbon (DOC) quantity and quality has created interest in managing peatlands for their ecosystem services such as drinking water provision. The evidence base for such interventions is, however, sometimes contradictory. We performed a laboratory climate manipulation using a factorial design on two dominant peatland vegetation types (Calluna vulgaris and Sphagnum Spp.) and a peat soil collected from a drinking water catchment in Exmoor National Park, UK. Temperature and rainfall were set to represent baseline and future conditions under the UKCP09 2080s high emissions scenario for July and August. DOC leachate then underwent standard water treatment of coagulation/flocculation before chlorination. C. vulgaris leached more DOC than Sphagnum Spp. (7.17 versus 3.00 mg g(-1)) with higher specific ultraviolet (SUVA) values and a greater sensitivity to climate, leaching more DOC under simulated future conditions. The peat soil leached less DOC (0.37 mg g(-1)) than the vegetation and was less sensitive to climate. Differences in coagulation removal efficiency between the DOC sources appears to be driven by relative solubilisation of protein-like DOC, observed through the fluorescence peak C/T. Post-coagulation only differences between vegetation types were detected for the regulated disinfection by-products (DBPs), suggesting climate change influence at this scale can be removed via coagulation. Our results suggest current biodiversity restoration programmes to encourage Sphagnum Spp. will result in lower DOC concentrations and SUVA values, particularly with warmer and drier summers. PMID:25262551

  7. Innovative method for increased methane recovery from two-phase anaerobic digestion of food waste through reutilization of acidogenic off-gas in methanogenic reactor.

    PubMed

    Yan, Bing Hua; Selvam, Ammaiyappan; Wong, Jonathan W C

    2016-10-01

    In this study, the performance of a two-phase anaerobic digestion reactor treating food waste with the reutilization of acidogenic off-gas was investigated with the objective to improve the hydrogen availability for the methanogenic reactor. As a comparison a treatment without off-gas reutilization was also set up. Results showed that acidogenic off-gas utilization in the upflow anaerobic sludge blanket (UASB) reactor increased the methane recovery up to 38.6%. In addition, a 27% increase in the production of cumulative chemical oxygen demand (COD) together with an improved soluble microbial products recovery dominated by butyrate was observed in the acidogenic leach bed reactor (LBR) with off-gas reutilization. Of the increased methane recovery, ∼8% was contributed by the utilization of acidogenic off-gas in UASB. Results indicated that utilization of acidogenic off-gas in methanogenic reactor is a viable technique for improving overall methane recovery. PMID:27039352

  8. Simulation of the dissolved nitrogen and phosphorus loads in different land uses in the Three Gorges Reservoir Region--based on the improved export coefficient model.

    PubMed

    Wang, Jinliang; Shao, Jing'an; Wang, Dan; Ni, Jiupai; Xie, Deti

    2015-11-01

    Nonpoint source pollution is one of the primary causes of eutrophication of water bodies. The concentrations and loads of dissolved pollutants have a direct bearing on the environmental quality of receiving water bodies. Based on the Johnes export coefficient model, a pollutant production coefficient was established by introducing the topographical index and measurements of annual rainfall. A pollutant interception coefficient was constructed by considering the width and slope of present vegetation. These two coefficients were then used as the weighting factors to modify the existing export coefficients of various land uses. A modified export coefficient model was created to estimate the dissolved nitrogen and phosphorus loads in different land uses in the Three Gorges Reservoir Region (TGRR) in 1990, 1995, 2000, 2005, and 2010. The results show that the new land use export coefficient was established by the modification of the production pollution coefficient and interception pollution coefficient. This modification changed the single numerical structure of the original land use export coefficient and takes into consideration temporal and spatial differentiation features. The modified export coefficient retained the change structure of the original single land use export coefficient, and also demonstrated that the land use export coefficient was not only impacted by the change of land use itself, but was also influenced by other objective conditions, such as the characteristics of the underlying surface, amount of rainfall, and the overall presence of vegetation. In the five analyzed years, the simulation values of the dissolved nitrogen and phosphorus loads in paddy fields increased after applying the modification in calculation. The dissolved nitrogen and phosphorus loads in dry land comprised the largest proportions of the TGRR's totals. After modification, the dry land values showed an initial increase and then a decrease over time, but the increments were

  9. Modelling of dissolved oxygen in the Danube River using artificial neural networks and Monte Carlo Simulation uncertainty analysis

    NASA Astrophysics Data System (ADS)

    Antanasijević, Davor; Pocajt, Viktor; Perić-Grujić, Aleksandra; Ristić, Mirjana

    2014-11-01

    This paper describes the training, validation, testing and uncertainty analysis of general regression neural network (GRNN) models for the forecasting of dissolved oxygen (DO) in the Danube River. The main objectives of this work were to determine the optimum data normalization and input selection techniques, the determination of the relative importance of uncertainty in different input variables, as well as the uncertainty analysis of model results using the Monte Carlo Simulation (MCS) technique. Min-max, median, z-score, sigmoid and tanh were validated as normalization techniques, whilst the variance inflation factor, correlation analysis and genetic algorithm were tested as input selection techniques. As inputs, the GRNN models used 19 water quality variables, measured in the river water each month at 17 different sites over a period of 9 years. The best results were obtained using min-max normalized data and the input selection based on the correlation between DO and dependent variables, which provided the most accurate GRNN model, and in combination the smallest number of inputs: Temperature, pH, HCO3-, SO42-, NO3-N, Hardness, Na, Cl-, Conductivity and Alkalinity. The results show that the correlation coefficient between measured and predicted DO values is 0.85. The inputs with the greatest effect on the GRNN model (arranged in descending order) were T, pH, HCO3-, SO42- and NO3-N. Of all inputs, variability of temperature had the greatest influence on the variability of DO content in river body, with the DO decreasing at a rate similar to the theoretical DO decreasing rate relating to temperature. The uncertainty analysis of the model results demonstrate that the GRNN can effectively forecast the DO content, since the distribution of model results are very similar to the corresponding distribution of real data.

  10. Final Report on Testing of Off-Gas Treatment Technologies for Abatement of Atmospheric Emissions of Chlorinated Volatile Organic Compounds

    SciTech Connect

    Jarosch, T.R.; Haselow, J.S.; Rossabi, J.; Burdick, S.A.; Raymond, R.; Young, J.E.; Lombard, K.H.

    1995-01-23

    The purpose of this report is to summarize the results of the program for off-gas treatment of atmospheric emissions of chlorinated volatile organic compounds (CVOCs), in particular trichloroethylene (TCE) and perchloroethylene (PCE). This program was funded through the Department of Energy Office of Technology Development`s VOC`s in Non-Arid Soils Integrated Demonstration (VNID). The off-gas treatment program was initiated after testing of in-situ air stripping with horizontal wells was completed (Looney et al., 1991). That successful test expectedly produced atmospheric emissions of CVOCs that were unabated. It was decided after that test that an off-gas treatment is an integral portion of remediation of CVOC contamination in groundwater and soil but also because several technologies were being developed across the United States to mitigate CVOC emissions. A single platform for testing off-gas treatment technologies would facilitate cost effective evaluation of the emerging technologies. Another motivation for the program is that many CVOCs will be regulated under the Clean Air Act Amendments of 1990 and are already regulated by many state regulatory programs. Additionally, compounds such as TCE and PCE are pervasive subsurface environmental contaminants, and, as a result, a small improvement in terms of abatement efficiency or cost will significantly reduce CVOC discharges to the environment as well as costs to United States government and industry.

  11. Distribution and Dynamic Properties of Xenon Dissolved in the Ionic Smectic Phase of [C16mim][NO3]: MD Simulation and Theoretical Model.

    PubMed

    Frezzato, Diego; Saielli, Giacomo

    2016-03-10

    We have investigated the structural and dynamic properties of Xe dissolved in the ionic liquid crystal (ILC) phase of 1-hexadecyl-3-methylimidazolium nitrate using classical molecular dynamics (MD) simulations. Xe is found to be preferentially dissolved within the hydrophobic environment of the alkyl chains rather than in the ionic layers of the smectic phase. The structural parameters and the estimated local diffusion coefficients concerning the short-time motion of Xe are used to parametrize a theoretical model based on the Smoluchowski equation for the macroscopic dynamics across the smectic layers, a feature which cannot be directly obtained from the relatively short MD simulations. This protocol represents an efficient combination of computational and theoretical tools to obtain information on slow processes concerning the permeability and diffusivity of the xenon in smectic ILCs. PMID:26848515

  12. MODELING THE IMPACT OF ELEVATED MERCURY IN DEFENSE WASTE PROCESSING FACILITY MELTER FEED ON THE MELTER OFF-GAS SYSTEM - PRELIMINARY REPORT

    SciTech Connect

    Zamecnik, J.; Choi, A.

    2009-03-25

    The Defense Waste Processing Facility (DWPF) is currently evaluating an alternative Chemical Process Cell (CPC) flowsheet to increase throughput. It includes removal of the steam-stripping step, which would significantly reduce the CPC processing time and lessen the sampling needs. However, its downside would be to send 100% of the mercury that come in with the sludge straight to the melter. For example, the new mercury content in the Sludge Batch 5 (SB5) melter feed is projected to be 25 times higher than that in the SB4 with nominal steam stripping of mercury. This task was initiated to study the impact of the worst-case scenario of zero-mercury-removal in the CPC on the DWPF melter off-gas system. It is stressed that this study is intended to be scoping in nature, so the results presented in this report are preliminary. In order to study the impact of elevated mercury levels in the feed, it is necessary to be able to predict how mercury would speciate in the melter exhaust under varying melter operating conditions. A homogeneous gas-phase oxidation model of mercury by chloride was developed to do just that. The model contains two critical parameters pertaining to the partitioning of chloride among HCl, Cl, Cl{sub 2}, and chloride salts in the melter vapor space. The values for these parameters were determined at two different melter vapor space temperatures by matching the calculated molar ratio of HgCl (or Hg{sub 2}Cl{sub 2}) to HgCl{sub 2} with those measured during the Experimental-Scale Ceramic Melter (ESCM) tests run at the Pacific Northwest National Laboratory (PNNL). The calibrated model was then applied to the SB5 simulant used in the earlier flowsheet study with an assumed mercury stripping efficiency of zero; the molar ratio of Cl-to-Hg in the resulting melter feed was only 0.4, compared to 12 for the ESCM feeds. The results of the model run at the indicated melter vapor space temperature of 650 C (TI4085D) showed that due to excessive shortage of

  13. Design and cost estimate for the SRL integrated hot off gas facility using selective adsorption

    SciTech Connect

    Pence, D T; Kirstein, B E

    1981-07-01

    Based on the results of an engineering-scale demonstration program, a design and cost estimate were performed for a 25-m/sup 3//h (15-ft/sup 3//min) capacity pilot plant demonstration system using selective adsorption technology for installation at the Integrated Hot Off Gas Facility at the Savannah River Plant. The design includes provisions for the destruction of NO/sub x/ and the concentration and removal of radioisotopes of ruthenium, iodine-129, tritiated water vapor, carbon-14 contaminated carbon dioxide, and krypton-85. The nobel gases are separated by the use of selective adsorption on mordenite-type zeolites. The theory of noble gas adsorption on zeolites is essentially the same as that for the adsorption of noble gases on activated charcoals. Considerable detail is provided regarding the application of the theory to adsorbent bed designs and operation. The design is based on a comprehensive material balance and appropriate heat transfer calculations. Details are provided on techniques and procedures used for heating, cooling, and desorbing the adsorbent columns. Analyses are also given regarding component and arrangement selection and includes discussions on alternative arrangements. The estimated equipment costs for the described treatment system is about $1,400,000. The cost estimate includes a detailed equipment list of all the major component items in the design. Related technical issues and estimated system performance are also discussed.

  14. Silica-based waste form for immobilization of iodine from reprocessing plant off-gas streams

    NASA Astrophysics Data System (ADS)

    Matyáš, Josef; Canfield, Nathan; Sulaiman, Sannoh; Zumhoff, Mac

    2016-08-01

    A high selectivity and sorption capacity for iodine and a feasible consolidation to a durable SiO2-based waste form makes silver-functionalized silica aerogel (Ag0-aerogel) an attractive choice for the removal and sequestration of iodine compounds from the off-gas of a nuclear fuel reprocessing plant. Hot uniaxial pressing of iodine-loaded Ag0-aerogel (20.2 mass% iodine) at 1200 °C for 30 min under 29 MPa pressure provided a partially sintered product with residual open porosity of 16.9% that retained ∼93% of sorbed iodine. Highly iodine-loaded Ag0-aerogel was successfully consolidated by hot isostatic pressing at 1200 °C with a 30-min hold and under 207 MPa. The fully densified waste form had a bulk density of 3.3 × 103 kg/m3 and contained ∼39 mass% iodine. The iodine was retained in the form of nano- and micro-particles of AgI that were uniformly distributed inside and along boundaries of fused silica grains.

  15. Simulation of carbon cycling, including dissolved organic carbon transport, in forest soil locally enriched with 14C

    SciTech Connect

    Tipping, Ed; Chamberlain, Paul M.; Froberg, Mats J.; Hanson, Paul J; Jardine, Philip M

    2012-01-01

    The DyDOC model was used to simulate organic matter decomposition and dissolved organic matter (DOM) transport in deciduous forest soils at the Oak Ridge Reservation (ORR) in Tennessee, USA. The model application relied on extensive data from the Enriched Background Isotope study (EBIS), which made use of a local atmospheric enrichment of radiocarbon to establish a large-scale manipulation experiment with different inputs of 14C from both above-ground and below-ground litter. The aim of the modelling was to test if the processes that constitute DyDOC can explain the available observations for C dynamics in the ORR. More specifically we used the model to investigate the origins of DOM, its dynamics within the soil profile, and how it contributes to the formation of stable carbon in the mineral soil. The model was first configured to account for water transport through the soil, then observed pools and fluxes of carbon and 14C data were used to fit the model parameters that describe the rates of the metabolic transformations. The soils were described by a thin O-horizon, a 15 cm thick A-horizon and a 45-cm thick B-horizon. Within the thin O-horizon, litter is either converted to CO2 or to a second organic matter pool, which is converted to CO2 at a different rate, both pools being able to produce DOM. The best model performance was obtained by assuming that adsorption of downwardly transported DOM in horizons A and B, followed by further conversion to stable forms, produces mineral-associated carbon pools, while root litter is the source of non-mineral associated carbon, with relatively short residence times. In the simulated steady-state, most carbon entering the O-horizon leaves quickly as CO2, but 17% (46 gC m-2 a-1) is lost as DOC in percolating water. The DOM comprises mainly hydrophobic material, 40% being derived from litter and 60% from older organic matter pools (residence time ~ 10 years). Most of the DOM is converted to CO2 in the mineral soil, over

  16. Microbial community evolution during simulated managed aquifer recharge in response to different biodegradable dissolved organic carbon (BDOC) concentrations.

    PubMed

    Li, Dong; Alidina, Mazahirali; Ouf, Mohamed; Sharp, Jonathan O; Saikaly, Pascal; Drewes, Jörg E

    2013-05-01

    This study investigates the evolution of the microbial community in laboratory-scale soil columns simulating the infiltration zone of managed aquifer recharge (MAR) systems and analogous natural aquifer sediment ecosystems. Parallel systems were supplemented with either moderate (1.1 mg/L) or low (0.5 mg/L) biodegradable dissolved organic carbon (BDOC) for a period of six months during which time, spatial (1 cm, 30 cm, 60 cm, 90 cm, and 120 cm) and temporal (monthly) analyses of sediment-associated microbial community structure were analyzed. Total microbial biomass associated with sediments was positively correlated with BDOC concentration where a significant decline in BDOC was observed along the column length. Analysis of 16S rRNA genes indicated dominance by Bacteria with Archaea comprising less than 1 percent of the total community. Proteobacteria was found to be the major phylum in samples from all column depths with contributions from Betaproteobacteria, Alphaproteobacteria and Gammaproteobacteria. Microbial community structure at all the phylum, class and genus levels differed significantly at 1 cm between columns receiving moderate and low BDOC concentrations; in contrast strong similarities were observed both between parallel column systems and across samples from 30 to 120 cm depths. Samples from 1 cm depth of the low BDOC columns exhibited higher microbial diversity (expressed as Shannon Index) than those at 1 cm of moderate BDOC columns, and both increased from 5.4 to 5.9 at 1 cm depth to 6.7-8.3 at 30-120 cm depths. The microbial community structure reached steady state after 3-4 months since the initiation of the experiment, which also resulted in an improved DOC removal during the same time period. This study suggested that BDOC could significantly influence microbial community structure regarding both composition and diversity of artificial MAR systems and analogous natural aquifer sediment ecosystems. PMID:23490107

  17. Simulated effects of anticipated coal mining on dissolved solids in selected tributaries of the Yampa River, northwestern Colorado

    USGS Publications Warehouse

    Parker, R.S.; Norris, J.M.

    1983-01-01

    Identifying cumulative effects of coal mining on dissolved solids downstream from multipe coal-mining operations is particularly important in western basins. The problem of identifying cumulative effects is evident in the Trout Creek drainage, a tributary to the Yampa River in northwestern Colorado, where a number of mines are active and mine expansions are planned. As an evaluation tool, a model was developed and calibrated for the Trout Creek drainage and a reach of the Yampa River main stem. This model uses a series of nodes on the stream network to sum water quantity and quality through the network. The model operates on a monthly basis and uses data from water years 1976 to 1981. Output is mean monthly discharge, dissolved-solids concentration, and dissolved-solids load. Observed data are needed to initiate the model and for model calibration. Some data were extrapolated from records of nearby streamflow-gaging stations. Some nodes within the stream network were for inputs from anticipated mining and were inactive during calibrations. After calibration, these nodes were used to input water discharge at a given dissolved-solids concentration to reflect various future mine configurations. (USGS)

  18. Advanced online monitoring of cell culture off-gas using proton transfer reaction mass spectrometry.

    PubMed

    Schmidberger, Timo; Gutmann, Rene; Bayer, Karl; Kronthaler, Jennifer; Huber, Robert

    2014-01-01

    Mass spectrometry has been frequently applied to monitor the O₂ and CO₂ content in the off-gas of animal cell culture fermentations. In contrast to classical mass spectrometry the proton transfer reaction mass spectrometry (PTR-MS) provides additional information of volatile organic compounds by application of a soft ionization technology. Hence, the spectra show less fragments and can more accurately assigned to particular compounds. In order to discriminate between compounds of non-metabolic and metabolic origin cell free experiments and fed-batch cultivations with a recombinant CHO cell line were conducted. As a result, in total eight volatiles showing high relevance to individual cultivation or cultivation conditions could be identified. Among the detected compounds methanethiol, with a mass-to-charge ratio of 49, qualifies as a key candidate in process monitoring due to its strong connectivity to lactate formation. Moreover, the versatile and complex data sets acquired by PTR MS provide a valuable resource for statistical modeling to predict non direct measurable parameters. Hence, partial least square regression was applied to the complete spectra of volatiles measured and important cell culture parameters such as viable cell density estimated (R²  = 0.86). As a whole, the results of this study clearly show that PTR-MS provides a powerful tool to improve bioprocess-monitoring for mammalian cell culture. Thus, specific volatiles emitted by cells and measured online by the PTR-MS and complex variables gained through statistical modeling will contribute to a deeper process understanding in the future and open promising perspectives to bioprocess control. PMID:24376199

  19. Analysis on storage off-gas emissions from woody, herbaceous, and torrefied biomass

    SciTech Connect

    Tumuluru, Jaya Shankar; Lim, C. Jim; Bi, Xiaotao T.; Kuang, Xingya; Melin, Staffan; Yazdanpanah, Fahimeh; Sokhansanj, Shahab

    2015-03-02

    Wood chips, torrefied wood chips, ground switchgrass, and wood pellets were tested for off-gas emissions during storage. Storage canisters with gas-collection ports were used to conduct experiments at room temperature of 20 °C and in a laboratory oven set at 40 °C. Commercially-produced wood pellets yielded the highest carbon monoxide (CO) emissions at both 20 and 40 °C (1600 and 13,000 ppmv), whereas torrefied wood chips emitted the lowest of about <200 and <2000 ppmv. Carbon dioxide (CO₂) emissions from wood pellets were 3000 ppmv and 42,000 ppmv, whereas torrefied wood chips registered at about 2000 and 25,000 ppmv, at 20 and 40 °C at the end of 11 days of storage. CO emission factors (milligrams per kilogram of biomass) calculated were lowest for ground switchgrass and torrefied wood chips (2.68 and 4.86 mg/kg) whereas wood pellets had the highest CO of about 10.60 mg/kg, respectively, at 40 °C after 11 days of storage. In the case of CO₂, wood pellets recorded the lowest value of 55.46 mg/kg, whereas switchgrass recorded the highest value of 318.72 mg/kg. This study concludes that CO emission factor is highest for wood pellets, CO₂ is highest for switchgrass and CH₄ is negligible for all feedstocks except for wood pellets, which is about 0.374 mg/kg at the end of 11-day storage at 40 °C.

  20. Removal of Mercury from the Off-Gas from Thermal Treatment of Radioactive Liquid Waste

    SciTech Connect

    Deldebbio, John Anthony; Olson, Lonnie Gene

    2001-05-01

    Acidic, radioactive wastes with a high nitrate concentration, and containing mercury are currently being stored at the Idaho Nuclear Technology and Engineering Center (INTEC). In the past, these wastes were converted into a dry, granular solid by a high temperature fluidized-bed calcination process. In the future, the calcined solids may be immobilized by a vitrification process prior to disposal. It has been proposed that a vitrification facility be built to treat the acidic wastes, as well as the calcined solids. As was the case with the calcination process, NOx levels in the vitrification off-gas are expected to be high, and mercury emissions are expected to exceed the Maximum Control Technology (MACT) limits. Mitigation of mercury emissions by wet scrubbing, followed by adsorption onto activated carbon is being investigated. Scoping tests with sulfur-impregnated activated carbon, KCl-impregnated activated carbon and non-impregnated activated carbon were conducted with a test gas containing1% NO2, 28% H2O, 4% O2 and 67% N2. Average removal efficiencies for Hgo and HgCl2 were 100 ± 2.5% and 99 ± 3.6% respectively, for sulfur-impregnated carbon. The KCl-impregnated carbon removed 99 ± 4.6% HgCl2. The removal efficiency of the non-impregnated carbon was 99 ± 3.6% for HgCl2. No short-term detrimental effects due to NO2 and H2O were observed. These results indicate that, placed downstream of a wet scrubber, an activated carbon adsorption bed has the potential of reducing mercury levels sufficiently to enable compliance with the MACT limit. Long-term exposure tests, and bed size optimization studies are planned for the future.

  1. Systematic selection of off-gas treatment at the Savannah River Site

    SciTech Connect

    McKillip, S.T.; Rehder, T.E.

    1992-01-01

    At the Savannah River Site (SRS), from 1958--1985, effluent waste from the reactor fuel and target rod fabrication area (M-Area) was discharged to a settling basin. In 1981, monitoring wells detected groundwater contamination, specifically trichloroethylene and tetrachloroethylene, in the immediate vicinity of the basin. Under the auspices of Resource Conservation and Recovery Act (RCRA) the M-Area contamination must be addressed by a corrective action program until the volatile organic compound (VOC) concentrations reach Drinking Water Standards. This was initiated in 1985 with startup of a full-scale pump-and-treat air stripper system. Recently, remediation efforts have focused on vacuum extraction to treat vadose zone contamination not addressed by the original recovery wells, and additional pump-and-treat systems to achieve hydraulic control of the plume. Regulatory requirements allowed for discharge of VOCs to the atmosphere when the original remediation system was installed; however, 1990 amendments to the Clean Air Act will eventually require treatment of VOC contaminated air prior to discharge. This has ramifications to systems currently being design, as well as the existing systems. In response to the 1990 Clean Air Act amendments, SRS initiated a study to assess commercially available off-gas treatment technologies. These included carbon adsorption, thermal incineration, catalytic oxidation, absorption, condensation, and UV/peroxide destruction, and xenon flashlamp. Criteria used to evaluate the technologies were the thirty (30) year life cycle cost, permitting considerations, and manpower requirements. The study concluded that catalytic oxidation provided the most desirable combination of these elements.

  2. Avoiding Carbon Bed Hot Spots in Thermal Process Off-Gas Systems

    SciTech Connect

    Nick Soelberg; Joe Enneking

    2011-05-01

    Mercury has had various uses in nuclear fuel reprocessing and other nuclear processes, and so is often present in radioactive and mixed (radioactive and hazardous) wastes. Test programs performed in recent years have shown that mercury in off-gas streams from processes that treat radioactive wastes can be controlled using fixed beds of activated sulfur-impregnated carbon, to levels low enough to comply with air emission regulations such as the Hazardous Waste Combustor (HWC) Maximum Achievable Control Technology (MACT) standards. Carbon bed hot spots or fires have occurred several times during these tests, and also during a remediation of tanks that contained mixed waste. Hot spots occur when localized areas in a carbon bed become heated to temperatures where oxidation occurs. This heating typically occurs due to heat of absoption of gas species onto the carbon, but it can also be caused through external means such as external heaters used to heat the carbon bed vessel. Hot spots, if not promptly mitigated, can grow into bed fires. Carbon bed hot spots and fires must be avoided in processes that treat radioactive and mixed waste. Hot spots are detected by (a) monitoring in-bed and bed outlet gas temperatures, and (b) more important, monitoring of bed outlet gas CO concentrations. Hot spots are mitigated by (a) designing for appropriate in-bed gas velocity, for avoiding gas flow maldistribution, and for sufficient but not excessive bed depth, (b) appropriate monitoring and control of gas and bed temperatures and compositions, and (c) prompt implementation of corrective actions if bed hot spots are detected. Corrective actions must be implemented quickly if bed hot spots are detected, using a graded approach and sequence starting with corrective actions that are simple, quick, cause the least impact to the process, and are easiest to recover from.

  3. Analysis on storage off-gas emissions from woody, herbaceous, and torrefied biomass

    DOE PAGESBeta

    Tumuluru, Jaya Shankar; Lim, C. Jim; Bi, Xiaotao T.; Kuang, Xingya; Melin, Staffan; Yazdanpanah, Fahimeh; Sokhansanj, Shahab

    2015-03-02

    Wood chips, torrefied wood chips, ground switchgrass, and wood pellets were tested for off-gas emissions during storage. Storage canisters with gas-collection ports were used to conduct experiments at room temperature of 20 °C and in a laboratory oven set at 40 °C. Commercially-produced wood pellets yielded the highest carbon monoxide (CO) emissions at both 20 and 40 °C (1600 and 13,000 ppmv), whereas torrefied wood chips emitted the lowest of about <200 and <2000 ppmv. Carbon dioxide (CO₂) emissions from wood pellets were 3000 ppmv and 42,000 ppmv, whereas torrefied wood chips registered at about 2000 and 25,000 ppmv, atmore » 20 and 40 °C at the end of 11 days of storage. CO emission factors (milligrams per kilogram of biomass) calculated were lowest for ground switchgrass and torrefied wood chips (2.68 and 4.86 mg/kg) whereas wood pellets had the highest CO of about 10.60 mg/kg, respectively, at 40 °C after 11 days of storage. In the case of CO₂, wood pellets recorded the lowest value of 55.46 mg/kg, whereas switchgrass recorded the highest value of 318.72 mg/kg. This study concludes that CO emission factor is highest for wood pellets, CO₂ is highest for switchgrass and CH₄ is negligible for all feedstocks except for wood pellets, which is about 0.374 mg/kg at the end of 11-day storage at 40 °C.« less

  4. Demonstration of a steam jet scrubber off-gas system and the burner efficiency of a mixed waste incinerator facility

    SciTech Connect

    Holmes, H; Charlesworth, D L

    1988-01-01

    A full-scale incinerator system, the Consolidated Incineration Facility (CIF), is being designed to process solid and liquid low-level radioactive, mixed, and RCRA hazardous waste. This facility will consist of a rotary kiln, secondary combustion chamber (SCC), and a wet off-gas system. A prototype steam jet scrubber off-gas system has been tested to verify design assumptions for the CIF. The scrubber wastewater will be immobilized in a cement matrix after the blowdown has been concentrated to a maximum solids concentration in a cross-flow filtration system. A sintered metal inertial filter system has been successfully tested. Burner efficiency was tested in a high intensity vortex burner, which destroyed the hazardous waste streams tested.

  5. MODELING THE IMPACT OF ELEVATED MERCURY IN DEFENSE WASTE PROCESSING FACILITY MELTER FEED ON THE MELTER OFF-GAS SYSTEM-PRELIMINARY REPORT

    SciTech Connect

    Zamecnik, J.; Choi, A.

    2010-08-18

    chloride, only 6% of the mercury fed is expected to get oxidized, mostly as HgCl, while the remaining mercury would exist either as elemental mercury vapor (90%) or HgO (4%). Noting that the measured chloride level in the SB5 qualification sample was an order of magnitude lower than that used in the SB5 simulant, the degree of chloride shortage will be even greater. As a result, the projected level of HgCl in the actual SB5 melter exhaust will be even lower than 6% of the total mercury fed, while that of elemental mercury is likely to be greater than 90%. The homogeneous oxidation of mercury in the off-gas was deemed to be of primary importance based on the postulation that mercury and other volatile salts form submicron sized aerosols upon condensation and thus remain largely in the gas stream downstream of the quencher where they can deposit in the off-gas lines, Steam-Atomized Scrubbers (SAS), and High-Efficiency Mist Eliminator (HEME). Formation of these submicron semi-volatile salts in the condensate liquid is considered to be unlikely, so the liquid phase reactions were considered to be less important. However, subsequent oxidation of mercury in the liquid phase in the off-gas system was examined in a simplified model of the off-gas condensate. It was found that the condensate chemistry was consistent with further oxidation of elemental mercury to Hg{sub 2}Cl{sub 2} and conversion of HgO to chlorides. The results were consistent with the available experimental data. It should also be noted that the model predictions presented in this report do not include any physically entrained solids, which typically account for much of the off-gas carryover on a mass basis. The high elemental mercury vapor content predicted at the DWPF Quencher inlet means that physically entrained solids could provide the necessary surface onto which elemental mercury vapor could condense, thereby coating the solids as well as the internal surfaces of the off-gas system with mercury. Clearly

  6. OGRE/MOD1: A computer model for predicting off-gas release from In Situ Vitrification melts

    SciTech Connect

    MacKinnon, R.J.; Mousseau, V.A.

    1990-07-01

    The OGRE program is designed to compute off-gas release from In Situ Vitrification melt pools. This document describes the theoretical basis and computational algorithms used in the program. An outline of the computer program is described including presentation of an example user input deck. Two model problems are examined to verify the program and an example problem is given to demonstrate program usage.

  7. Formation of the ZnFe2O4 phase in an electric arc furnace off-gas treatment system.

    PubMed

    Suetens, T; Guo, M; Van Acker, K; Blanpain, B

    2015-04-28

    To better understand the phenomena of ZnFe2O4 spinel formation in electric arc furnace dust, the dust was characterized with particle size analysis, X-ray fluorescence (XRF), electron backscatter diffraction (EBSD), and electron probe micro-analysis (EPMA). Different ZnFe2O4 formation reaction extents were observed for iron oxide particles with different particle sizes. ZnO particles were present as both individual particles and aggregated on the surface of larger particles. Also, the slag particles found in the off-gas were shown not to react with the zinc vapor. After confirming the presence of a ZnFe2O4 formation reaction, the thermodynamic feasibility of in-process separation - a new electric arc furnace dust treatment technology - was reevaluated. The large air intake and the presence of iron oxide particles in the off-gas were included into the thermodynamic calculations. The formation of the stable ZnFe2O4 spinel phase was shown to be thermodynamically favorable in current electric arc furnace off-gas ducts conditions even before reaching the post combustion chamber. PMID:25646901

  8. Calibration and use of an interactive-accounting model to simulate dissolved solids, streamflow, and water-supply operations in the Arkansas River basin, Colorado

    USGS Publications Warehouse

    Burns, A.W.

    1989-01-01

    An interactive-accounting model was used to simulate dissolved solids, streamflow, and water supply operations in the Arkansas River basin, Colorado. Model calibration of specific conductance to streamflow relations at three sites enabled computation of dissolved-solids loads throughout the basin. To simulate streamflow only, all water supply operations were incorporated in the regression relations for streamflow. Calibration for 1940-85 resulted in coefficients of determination that ranged from 0.89 to 0.58, and values in excess of 0.80 were determined for 16 of 20 nodes. The model then incorporated 74 water users and 11 reservoirs to simulate the water supply operations for two periods, 1943-74 and 1975-85. For the 1943-74 calibration, coefficients of determination for streamflow ranged from 0.87 to 0.02. Calibration of the water supply operations resulted in coefficients of determination that ranged from 0.87 to negative for simulated irrigation diversions of 37 selected water users. Calibration for 1975-85 was not evaluated statistically, but average values and plots of reservoir contents indicated reasonableness of the simulation. To demonstrate the utility of the model, six specific alternatives were simulated to consider effects of potential enlargement of Pueblo Reservoir. Three general major alternatives were simulated: the 1975-85 calibrated model data, the calibrated model data with an addition of 30 cu ft/sec in Fountain Creek flows, and the calibrated model data plus additional municipal water in storage. These three major alternatives considered the options of reservoir enlargement or no enlargement. A 40,000-acre-foot reservoir enlargement resulted in average increases of 2,500 acre-ft in transmountain diversions, of 800 acre-ft in storage diversions, and of 100 acre-ft in winter-water storage. (USGS)

  9. Airborne waste management technology applicable for use in reprocessing plants for control of iodine and other off-gas constituents

    SciTech Connect

    Jubin, R.T.

    1988-02-01

    Extensive work in the area of iodine removal from reprocessing plant off-gas streams using various types of solid sorbent materials has been conducted worldwide over the past two decades. This work has focused on the use of carbon filters, primarily for power plant applications. More recently, the use of silver-containing sorbents has been the subject of considerable research. The most recent work in the United States has addressed the use of silver-exchanged faujasites and mordenites. The chemical reactions of iodine with silver on the sorbent are not well defined, but it is generally believed that chemisorbed iodides and iodates are formed. The process for iodine recovery generally involves passage of the iodine-laden gas stream through a packed bed of the adsorbent material preheated to a temperature of about 150/degree/C. Most iodine removal system designs utilizing silver-containing solid sorbents assume only a 30 to 50% silver utilization. Based on laboratory tests, potentially 60 to 70% of the silver contained in the sorbents can be reacted with iodine. To overcome the high cost of silver associated with these materials, various approaches have been explored. Among these are the regeneration of the silver-containing sorbent by stripping the iodine and trapping the iodine on a sorbent that has undergone only partial silver exchange and is capable of attaining a much higher silver utilization. This summary report describes the US work in regeneration of iodine-loaded solid sorbent material. In addition, the report discusses the broader subject of plant off-gas treatment including system design. The off-gas technologies to recovery No/sub x/ and to recover and dispose of Kr, /sup 14/C, and I are described as to their impacts on the design of an integrated off-gas system. The effect of ventilation philosophy for the reprocessing plant is discussed as an integral part of the overall treatment philosophy of the plant off-gas. 103 refs., 5 figs., 8 tabs.

  10. Structure-property relationship of metal-organic frameworks (MOFs) and physisorbed off-gas radionuclides.

    SciTech Connect

    Nenoff, Tina Maria; Chupas, Peter J.; Garino, Terry J.; Rodriguez, Mark Andrew; Chapman, Karena W.; Sava, Dorina Florentina

    2010-11-01

    We report on the host-guest interactions between metal-organic frameworks (MOFs) with various profiles and highly polarizable molecules (iodine), with emphasis on identifying preferential sorption sites in these systems. Radioactive iodine 129I, along with other volatile radionuclides (3H, 14C, Xe and Kr), represents a relevant component in the off-gas resulted during nuclear fuel reprocessing. Due to its very long half-life, 15.7 x 106 years, and potential health risks in humans, its efficient capture and long-term storage is of great importance. The leading iodine capture technology to date is based on trapping iodine in silver-exchanged mordenite. Our interests are directed towards improving existent capturing technologies, along with developing novel materials and alternative waste forms. Herein we report the first study that systematically monitors iodine loading onto MOFs, an emerging new class of porous solid-state materials. In this context, MOFs are of particular interest as: (i) they serve as ideal high capacity storage media, (ii) they hold potential for the selective adsorption from complex streams, due to their high versatility and tunability. This work highlights studies on both newly developed in our lab, and known highly porous MOFs that all possess distinct characteristics (specific surface area, pore volume, pore size, and dimension of the window access to the pore). The materials were loaded to saturation, where elemental iodine was introduced from solution, as well as from vapor phase. Uptakes in the range of {approx}125-150 wt% I2 sorbed were achieved, indicating that these materials outperform all other solid adsorbents to date in terms of overall capacity. Additionally, the loaded materials can be efficiently encapsulated in stable waste forms, including as low temperature sintering glasses. Ongoing studies are focused on gathering qualitative information with respect to localizing the physisorbed iodine molecules within the frameworks: X

  11. Mutual and Self-Diffusivities in Binary Mixtures of [EMIM][B(CN)4] with Dissolved Gases by Using Dynamic Light Scattering and Molecular Dynamics Simulations.

    PubMed

    Koller, Thomas M; Heller, Andreas; Rausch, Michael H; Wasserscheid, Peter; Economou, Ioannis G; Fröba, Andreas P

    2015-07-01

    Ionic liquids (ILs) are possible working fluids for the separation of carbon dioxide (CO2) from flue gases. For evaluating their performance in such processes, reliable mutual-diffusivity data are required for mixtures of ILs with relevant flue gas components. In the present study, dynamic light scattering (DLS) and molecular dynamics (MD) simulations were used for the investigation of the molecular diffusion in binary mixtures of the IL 1-ethyl-3-methylimidazolium tetracyanoborate ([EMIM][B(CN)4]) with the dissolved gases carbon dioxide, nitrogen, carbon monoxide, hydrogen, methane, oxygen, and hydrogen sulfide at temperatures from 298.15 to 363.15 K and pressures up to 63 bar. At conditions approaching infinite dilution of a gas, the Fick mutual diffusivity of the mixture measured by DLS and the self-diffusivity of the corresponding gas calculated by MD simulations match, which could be generally found within combined uncertainties. The obtained diffusivities are in agreement with literature data for the same or comparable systems as well as with the general trend of increasing diffusivities for decreasing IL viscosities. The DLS and MD results reveal distinctly larger molecular diffusivities for [EMIM][B(CN)4]-hydrogen mixtures compared to mixtures with all other gases. This behavior results in the failure of an empirical correlation with the molar volumes of the gases at their normal boiling points. The DLS experiments also showed that there is no noticeable influence of the dissolved gas and temperature on the thermal diffusivity of the studied systems. PMID:26075680

  12. Numerical Simulations of Bubble Dynamics and Heat Transfer in Pool Boiling---Including the Effects of Conjugate Conduction, Level of Gravity, and Noncondensable Gas Dissolved in the Liquid

    NASA Astrophysics Data System (ADS)

    Aktinol, Eduardo

    Due to the complex nature of the subprocesses involved in nucleate boiling, it has not been possible to develop comprehensive models or correlations despite decades of accumulated data and analysis. Complications such as the presence of dissolved gas in the liquid further confound attempts at modeling nucleate boiling. Moreover, existing empirical correlations may not be suitable for new applications, especially with regards to varying gravity level. More recently, numerical simulations of the boiling process have proven to be capable of reliably predicting bubble dynamics and associated heat transfer by showing excellent agreement with experimental data. However, most simulations decouple the solid substrate by assuming constant wall temperature. In the present study complete numerical simulations of the boiling process are performed---including conjugate transient conduction in the solid substrate and the effects of dissolved gas in the liquid at different levels of gravity. Finite difference schemes are used to discretize the governing equations in the liquid, vapor, and solid phases. The interface between liquid and vapor phases is tracked by a level set method. An iterative procedure is used at the interface between the solid and fluid phases. Near the three-phase contact line, temperatures in the solid are observed to fluctuate significantly over short periods. The results show good agreement with the data available in the literature. The results also show that waiting and growth periods can be related directly to wall superheat. The functional relationship between waiting period and wall superheat is found to agree well with empirical correlations reported in the literature. For the case of a single bubble in subcooled nucleate boiling, the presence of dissolved gas in the liquid is found to cause noncondensables to accumulate at the top of the bubble where most condensation occurs. This results in reduced local saturation temperature and condensation rates

  13. Optimization of UA of heat exchangers and BOG compressor exit pressure of LNG boil-off gas reliquefaction system using exergy analysis

    NASA Astrophysics Data System (ADS)

    Kochunni, Sarun Kumar; Ghosh, Parthasarathi; Chowdhury, Kanchan

    2015-12-01

    Boil-off gas (BOG) generation and its handling are important issues in Liquefied natural gas (LNG) value chain because of economic, environment and safety reasons. Several variants of reliquefaction systems of BOG have been proposed by researchers. Thermodynamic analyses help to configure them and size their components for improving performance. In this paper, exergy analysis of reliquefaction system based on nitrogen-driven reverse Brayton cycle is carried out through simulation using Aspen Hysys 8.6®, a process simulator and the effects of heat exchanger size with and without related pressure drop and BOG compressor exit pressure are evaluated. Nondimensionalization of parameters with respect to the BOG load allows one to scale up or down the design. The process heat exchanger (PHX) requires much higher surface area than that of BOG condenser and it helps to reduce the quantity of methane vented out to atmosphere. As pressure drop destroys exergy, optimum UA of PHX decreases for highest system performance if pressure drop is taken into account. Again, for fixed sizes of heat exchangers, as there is a range of discharge pressures of BOG compressor at which the loss of methane in vent minimizes, the designer should consider choosing the pressure at lower value.

  14. Process system evaluation-consolidated letters. Volume 1. Alternatives for the off-gas treatment system for the low-level waste vitrification process

    SciTech Connect

    Peurrung, L.M.; Deforest, T.J; Richards, J.R.

    1996-03-01

    This report provides an evaluation of alternatives for treating off-gas from the low-level waste (LLW) melter. The study used expertise obtained from the commercial nonradioactive off-gas treatment industry. It was assumed that contact maintenance is possible, although the subsequent risk to maintenance personnel was qualitatively considered in selecting equipment. Some adaptations to the alternatives described may be required, depending on the extent of contact maintenance that can be achieved. This evaluation identified key issues for the off-gas system design. To provide background information, technology reviews were assembled for various classifications of off-gas treatment equipment, including off-gas cooling, particulate control, acid gas control, mist elimination, NO{sub x} reduction, and SO{sub 2} removal. An order-of-magnitude cost estimate for one of the off-gas systems considered is provided using both the off-gas characteristics associated with the Joule-heated and combustion-fired melters. The key issues identified and a description of the preferred off-gas system options are provided below. Five candidate treatment systems were evaluated. All of the systems are appropriate for the different melting/feed preparations currently being considered. The lowest technical risk is achieved using option 1, which is similar to designs for high-level waste (HLW) vitrification in the Hanford Waste Vitrification Project (HWVP) and the West Valley. Demonstration Project. Option 1 uses a film cooler, submerged bed scrubber (SBS), and high-efficiency mist eliminator (HEME) prior to NO{sub x} reduction and high-efficiency particulate air (HEPA) filtration. However, several advantages were identified for option 2, which uses high-temperature filtration. Based on the evaluation, option 2 was identified as the preferred alternative. The characteristics of this option are described below.

  15. Effects of dissolved oxygen on microbial community of single-stage autotrophic nitrogen removal system treating simulating mature landfill leachate.

    PubMed

    Wen, Xin; Zhou, Jian; Wang, Jiale; Qing, Xiaoxia; He, Qiang

    2016-10-01

    The performance of four identical sequencing biofilm batch reactors (SBBR) for autotrophic nitrogen removal was investigated with 2000mg/L ammonia-containing mature landfill leachate at 30°C. The main objective of this study was to evaluate the effects of dissolved oxygen (DO) on the performance and microbial community of single-stage nitrogen removal using anammox and partial nitritation (SNAP) system. At an applied load of 0.5kgNm(-3)d(-1), average total nitrogen removal efficiency (TNRE) above 90% was long-term achieved with an optimal DO concentration of 2.7mg/L. The microelectrode-measured profiles showed the microenvironments inside the biofilms. 16S ribosomal Ribonucleic Acid (rRNA) amplicon pyrosequencing and denaturing gradient gel electrophoresis (DGGE) were used to analyze the microbial variations of different DO concentrations and different positions inside one reactor. PMID:27450126

  16. Effect of temperature and dissolved hydrogen on oxide films formed on Ni and Alloy 182 in simulated PWR water

    NASA Astrophysics Data System (ADS)

    Mendonça, R.; Bosch, R.-W.; Van Renterghem, W.; Vankeerberghen, M.; de Araújo Figueiredo, C.

    2016-08-01

    Alloy 182 is a nickel-based weld metal, which is susceptible to stress corrosion cracking in PWR primary water. It shows a peak in SCC susceptibility at a certain temperature and hydrogen concentration. This peak is related to the electrochemical condition where the Ni to NiO transition takes place. One hypothesis is that the oxide layer at this condition is not properly developed and so the material is not optimally protected against SCC. Therefore the oxide layer formed on Alloy 182 is investigated as a function of the dissolved hydrogen concentration and temperature around this Ni/NiO transition. Exposure tests were performed with Alloy 182 and Ni coupons in a PWR environment at temperatures between 300 °C and 345 °C and dissolved hydrogen concentration between 5 and 35 cc (STP)H2/kg. Post-test analysis of the formed oxide layers were carried out by SEM, EDS and XPS. The exposure tests with Ni coupons showed that the Ni/NiO transition curve is at a higher temperature than the curve based on thermodynamic calculations. The exposure tests with Alloy 182 showed that oxide layers were present at all temperatures, but that the morphology changed from spinel crystals to needle like oxides when the Ni/NiO transition curve was approached. Oxide layers were present below the Ni/NiO transition curve i.e. when the Ni coupon was still free of oxides. In addition an evolved slip dissolution model was proposed that could explain the observed experimental results and the peak in SCC susceptibility for Ni-based alloys around the Ni/NiO transition.

  17. Novel synthesis of bismuth-based adsorbents for the removal of 129I in off-gas

    NASA Astrophysics Data System (ADS)

    Yang, Jae Hwan; Shin, Jin Myeong; Park, Jang Jin; Park, Geun Il; Yim, Man Sung

    2015-02-01

    New adsorbents based on bismuth were investigated for the capture of iodine-129 (129I) in off-gas produced from spent fuel reprocessing. Porous bulky materials were synthesized with polyvinyl alcohol (PVA) as a sacrificial template. Our findings showed that the iodine trapping capacity of as-synthesized samples could reach 1.9-fold that of commercial silver-exchanged zeolite (AgX). The thermodynamic stability of the reaction products explains the high removal efficiency of iodine. We also found that the pore volume of each sample was closely related to the ratio of the reaction products.

  18. SNL Sigma Off-Gas Team Contribution to the FY15 DOE/NE-MRWFD Campaign Accomplishments Report.

    SciTech Connect

    Nenoff, Tina M.

    2015-08-21

    This program at Sandia is focused on Iodine waste form development for Fuel Cycle R&D needs. Our research has a general theme of “Capture and Storage of Iodine Fission Gas “ in which we are focused on silver loaded zeolite waste forms, evaluation of iodine loaded getter materials (eg., mordenite zeolite), and the development of low temperature glass waste forms that successfully incorporate iodine loaded getter materials from I2, organic iodide, etc. containing off-gas streams.

  19. FLOWSHEET EVALUATION FOR THE DISSOLVING AND NEUTRALIZATION OF SODIUM REACTOR EXPERIMENT USED NUCLEAR FUEL

    SciTech Connect

    Daniel, W. E.; Hansen, E. K.; Shehee, T. C.

    2012-10-30

    This report includes the literature review, hydrogen off-gas calculations, and hydrogen generation tests to determine that H-Canyon can safely dissolve the Sodium Reactor Experiment (SRE; thorium fuel), Ford Nuclear Reactor (FNR; aluminum alloy fuel), and Denmark Reactor (DR-3; silicide fuel, aluminum alloy fuel, and aluminum oxide fuel) assemblies in the L-Bundles with respect to the hydrogen levels in the projected peak off-gas rates. This is provided that the number of L-Bundles charged to the dissolver is controlled. Examination of SRE dissolution for potential issues has aided in predicting the optimal batching scenario. The calculations detailed in this report demonstrate that the FNR, SRE, and DR-3 used nuclear fuel (UNF) are bounded by MURR UNF and may be charged using the controls outlined for MURR dissolution in a prior report.

  20. Simulated Passage Through A Modified Kaplan Turbine Pressure Regime: A Supplement to "Laboratory Studies of the Effects of Pressure and Dissolved Gas Supersaturation on Turbine-Passed Fish"

    SciTech Connect

    Abernethy, Cary S.; Amidan, Brett G.; Cada, G. F.

    2002-03-15

    Migratory and resident fish in the Columbia River basin are exposed to stresses associated with hydroelectric power production, including pressure changes during turbine passage and dissolved gas supersaturation (resulting from the release of water from the spillway). The responses of fall Chinook salmon and bluegill sunfish to these two stresses, both singly and in combination, were investigated in the laboratory. A previous test series (Abernethy et al. 2001) evaluated the effects of passage through a Kaplan turbine under the ?worst case? pressure conditions. For this series of tests, pressure changes were modified to simulate passage through a Kaplan turbine under a more ?fish-friendly? mode of operation. The results were compared to results from Abernethy et al. (2001). Fish were exposed to total dissolved gas (TDG) levels of 100%, 120%, or 135% of saturation for 16-22 hours at either surface (101 kPa) or 30 ft (191 kPa) of pressure, then held at surface pressure at 100% saturation for a 48-hour observation period. Sensitivity of fall Chinook salmon to gas supersaturation was slightly higher than in the previous test series, with 15% mortality for surface-acclimated fish at 120% TDG, compared to 0% in the previous tests.

  1. A simple simulation of adsorption equilibrium of Pb(II) on Andosols in the presence of dissolved humic substances for monitoring soil contamination.

    PubMed

    Liu, Yuyu; Kobayashi, Takeshi; Takahashi, Yukari; Kameya, Takashi; Urano, Kohei

    2013-01-01

    The adsorption equilibrium of Pb(II) on Andosols was investigated and described quantitatively in order to develop a simple method for the rapid monitoring of heavy metals in soils. The effect of solution pH on adsorption isotherms was investigated experimentally and in simulations. At pH 7, the considerable desorption of Pb(II) due to the extensive dissolution of humic substances (HS) from soils into aqueous phases is known to be an obstacle to carrying out simulations. In batch experiments, the total organic carbon (TOC) of the aqueous phases was shown to be enhanced by the addition of pre-extracted HS to soil suspensions. By combining the ion-exchange and Freundlich models, the adsorption equilibriums of free Pb(2+) ions and Pb(2+)-HS were simulated and were shown to be in good agreement with the experimental results. By estimating the concentrations and adsorption amounts of Pb(2+) and Pb(2+)-HS from measured CPb and TOC, it is possible to accurately simulate the soil contamination status even in in the presence of dissolved HS in the water in the solid-liquid extraction samples. PMID:23947708

  2. LFCM (liquid-fed eramic melter) emission and off-gas system performance for feed component cesium

    SciTech Connect

    Goles, R.W.; Andersen, C.M.

    1986-09-01

    Except for volatile off-gas effluents, overall adequacy of the liquid-fed ceramic melter (LFCM) system depends most upon its effectiveness in dealing with cesium. However, the mechanism responsible for melter cesium losses has proved insensitive to many LFCM operating and processing conditions. As a result, variations in inleakage, plenum temperature, feeding rate and waste loading do not significantly influence melter cesium performance. Feed composition, specifically halogen content, is the only processing variable that has had a significant effect. Due to the submicron nature of LFCM-generated aerosols, melter disengagement design features are not expected to be particularly effective in reducing cesium emission rates. For the same reason, the cesium performance of conventional quench scrubbers is quite low, being dependent only upon the magnitude of melter entrainment losses. Although a deep bed washable filter has been effective in removing submicron aerosols from the process exhaust, high performance has only been achieved under dry operating conditions. The melter's idling state does not appear to place additional demands upon the off-gas treatment system.

  3. Flow field and dissolved oxygen distributions in the outer channel of the Orbal oxidation ditch by monitor and CFD simulation.

    PubMed

    Guo, Xuesong; Zhou, Xin; Chen, Qiuwen; Liu, Junxin

    2013-04-01

    In the Orbal oxidation ditch, denitrification is primarily accomplished in the outer channel. However, the detailed characteristics of the flow field and dissolved oxygen (DO) distribution in the outer channel are not well understood. Therefore, in this study, the flow velocity and DO concentration in the outer channel of an Orbal oxidation ditch system in a wastewater treatment plant in Beijing (China) were monitored under actual operation conditions. The flow field and DO concentration distributions were analyzed by computed fluid dynamic modeling. In situ monitoring and modeling both showed that the flow velocity was heterogeneous in the outer channel. As a result, the DO was also heterogeneously distributed in the outer channel, with concentration gradients occurring along the flow direction as well as in the cross-section. This heterogeneous DO distribution created many anoxic and aerobic zones, which may have facilitated simultaneous nitrification-denitrification in the channel. These findings may provide supporting information for rational optimization of the performance of the Orbal oxidation ditch. PMID:23923772

  4. Properties of Poloxamer Molecules and Poloxamer Micelles Dissolved in Water and Next to Lipid Bilayers: Results from Computer Simulations.

    PubMed

    Adhikari, Upendra; Goliaei, Ardeshir; Tsereteli, Levan; Berkowitz, Max L

    2016-07-01

    To study the properties of poloxamer molecules P85 and P188 and micelles containing these poloxamers in bulk water and also next to lipid bilayers, we performed coarse-grained molecular dynamics computer simulations. We used MARTINI force-field and adjusted Lennard-Jones nonbonded interaction strength parameters for poloxamer beads to take into account the presence of polarizable water. Simulations of systems containing poloxamer molecules or micelles solvated in bulk water showed that structural properties, such as radii of gyration of the molecules and micelles, agree with the ones inferred from experiments. We observed that P85 micelle is almost spherical in shape, whereas the P188 micelle is distorted from being spherical. Simulations containing systems with the water-lipid bilayer interface showed that hydrophilic blocks of poloxamers interact with lipid headgroups of the bilayer and remain at the interface, whereas hydrophobic blocks prefer to insert into the central hydrophobic region of the bilayer. Simulations containing poloxamer micelles next to lipid bilayer showed no permeation of these micelles into the bilayer. To study the "healing" properties of P188 poloxamer, we performed simulations on a system containing a P188 micelle next to "damaged" lipid bilayer containing a pore. We observed that hydrophobic chains of poloxamers got inserted into the bilayer through the pore region, ultimately closing the pore. PMID:26719970

  5. On structural features of fullerene C60 dissolved in carbon disulfide: complementary study by small-angle neutron scattering and molecular dynamic simulations.

    PubMed

    Avdeev, M V; Tropin, T V; Bodnarchuk, I A; Yaradaikin, S P; Rosta, L; Aksenov, V L; Bulavin, L A

    2010-04-28

    The parameters of fullerene C(60) dissolved in carbon disulfide CS(2) are analyzed by small-angle neutron scattering (SANS) in a wide interval of momentum transfer. To exclude the influence of nonequilibrium conditions, the solutions are prepared without applying shaking, stirring or ultrasound. No indication of the equilibrium cluster state of C(60) (with the cluster size below 60 nm) in the final solutions is revealed. Molecular dynamic simulations are complementary used to find out the partial volume of C(60) in CS(2) and the scattering contribution of the solvent organization at the interface with the fullerene molecule, which is shown to be small. Among several approaches for describing SANS data the preference is given to the model, which takes into account the presence of stable C(60) dimers (comprising 10% of the total particle number density) in the solution. PMID:20441296

  6. Distributions of 14 elements on 60 selected absorbers from two simulant solutions (acid-dissolved sludge and alkaline supernate) for Hanford HLW Tank 102-SY

    SciTech Connect

    Marsh, S.F.; Svitra, Z.V.; Bowen, S.M.

    1993-10-01

    Sixty commercially available or experimental absorber materials were evaluated for partitioning high-level radioactive waste. These absorbers included cation and anion exchange resins, inorganic exchangers, composite absorbers, and a series of liquid extractants sorbed on porous support-beads. The distributions of 14 elements onto each absorber were measured from simulated solutions that represent acid-dissolved sludge and alkaline supernate solutions from Hanford high-level waste (HLW) Tank 102-SY. The selected elements, which represent fission products (Ce, Cs, Sr, Tc, and Y); actinides (U, Pu, and Am); and matrix elements (Cr, Co, Fe, Mn, Zn, and Zr), were traced by radionuclides and assayed by gamma spectrometry. Distribution coefficients for each of the 1680 element/absorber/solution combinations were measured for dynamic contact periods of 30 min, 2 h, and 6 h to provide sorption kinetics information for the specified elements from these complex media. More than 5000 measured distribution coefficients are tabulated.

  7. Simulating unsteady transport of nitrogen, biochemical oxygen demand, and dissolved oxygen in the Chattahoochee River downstream from Atlanta, Georgia

    USGS Publications Warehouse

    Jobson, Harvey E.

    1985-01-01

    As part of an intensive water-quality assessment of the Chattahoochee River, repetitive water-quality measurements were made at 12 sites along a 69-kilometer reach of the river downstream of Atlanta, Georgia. Concentrations of seven constituents (temperature, dissolved oxygen, ultimate carbonaceous biochemical oxygen demand (BOD), organic nitrogen, ammonia, nitrite, and nitrate) were obtained during two periods of 36 hours, one starting on August 30, 1976, and the other starting on May 31, 1977. The study reach contains one large and several small sewage outfalls and receives the cooling water from two large powerplants. An unsteady water-quality model of the Lagrangian type was calibrated using the 1977 data and verified using the 1976 data. The model provided a good means of interpreting these data even though both the flow and the pollution loading rates were highly unsteady. A kinetic model of the cascade type accurately described the physical and biochemical processes occurring in the river. All rate coefficients, except reaeration coefficients and those describing the resuspension of BOD, were fitted to the 1977 data and verified using the 1976 data. The study showed that, at steady low flow, about 38 percent of the BOD settled without exerting an oxygen demand. At high flow, this settled BOD was resuspended and exerted an immediate oxygen demand. About 70 percent of the ammonia extracted from the water column was converted to nitrite, but the fate of the remaining 30 percent is unknown. Photosynthetic production was not an important factor in the oxygen balance during either run.

  8. Molecular Dynamics Simulation Study of the NMR Relaxation of Xenon-131 Dissolved in 1,3-Dioxane and 1,4-Dioxane

    NASA Astrophysics Data System (ADS)

    Luhmer, M.; Reisse, J.

    The experimental NMR relaxation study of Xe-131 dissolved in 1,3-dioxane and 1,4-dioxane indicates that the intermolecular quadrupole relaxation mechanism is equally as efficient in both solvents even if 1,3-dioxane is a dipolar molecule while 1,4-dioxane is not. In order to interpret this observation, molecular-dynamics simulations were performed for model systems of xenon gas dissolved in 1,3-dioxane and 1,4-dioxane. The simulations were able to satisfactorily reproduce various experimental data for each system and, in perfect agreement with the experiment, yielded the same 131Xe quadrupole relaxation rate in both solvents. This result was obtained assuming an electrostatic origin of the electric-field gradient, and therefore validates this explanation. In 1,4-dioxane, the overwhelming part of the fluctuating electric-field gradient experienced by the xenon nucleus is due to the quadrupole moment of the solvent molecules. In 1,3-dioxane, the dipole moment is responsible for approximately half the value of the amplitude of the electric-field-gradient fluctuations only. Contributions at least up to the octopole moment are important and, consequently, the correlation time characterizing the electric-field-gradient fluctuations in 1,3-dioxane is significantly shorter than the dipolar correlation time and is found to be similar to the correlation time value in 1,4-dioxane. The relaxation rate of 131Xe in dioxanes is compared to the value in other solvents including cyclohexane, and comments are made on the general concept of polarity.

  9. A Literature Survey to Identify Potentially Volatile Iodine-Bearing Species Present in Off-Gas Streams

    SciTech Connect

    Bruffey, S. H.; Spencer, B. B.; Strachan, D. M.; Jubin, R. T.; Soelberg, N. R.; Riley, B. J.

    2015-06-30

    Four radionuclides have been identified as being sufficiently volatile in the reprocessing of nuclear fuel that their gaseous release needs to be controlled to meet regulatory requirements (Jubin et al. 2011, 2012). These radionuclides are 3H, 14C, 85Kr, and 129I. Of these, 129I has the longest half-life and potentially high biological impact. Accordingly, control of the release of 129I is most critical with respect to the regulations for the release of radioactive material in stack emissions. It is estimated that current EPA regulations (EPA 2010) would require any reprocessing plant in the United States to limit 129I release to less than 0.05 Ci/MTIHM for a typical fuel burnup of 55 gigawatt days per metric tonne (GWd/t) (Jubin 2011). The study of inorganic iodide in off-gas systems has been almost exclusively limited to I2 and the focus of organic iodide studies has been CH3I. In this document, we provide the results of an examination of publically available literature that is relevant to the presence and sources of both inorganic and organic iodine-bearing species in reprocessing plants. We especially focus on those that have the potential to be poorly sequestered with traditional capture methodologies. Based on the results of the literature survey and some limited thermodynamic modeling, the inorganic iodine species hypoiodous acid (HOI) and iodine monochloride (ICl) were identified as potentially low-sorbing iodine species that could present in off-gas systems. Organic species of interest included both short chain alkyl iodides such as methyl iodide (CH3I) and longer alkyl iodides up to iodododecane (C10H21I). It was found that fuel dissolution may provide conditions conducive to HOI formation and has been shown to result in volatile long-chain alkyl iodides, though these may not volatilize until later in the reprocessing sequence. Solvent extraction processes were found to be significant sources of various organic iodine-bearing species; formation of these

  10. DEVELOPMENT OF A HYDROGEN MORDENITE SORBENT FOR THE CAPTURE OF KRYPTON FROM USED NUCLEAR FUEL REPROCESSING OFF-GAS STREAMS

    SciTech Connect

    Mitchell Greenhalgh; Troy G. Garn; Jack D. Law

    2014-04-01

    A novel new sorbent for the separation of krypton from off-gas streams resulting from the reprocessing of used nuclear fuel has been developed and evaluated. A hydrogen mordenite powder was successfully incorporated into a macroporous polymer binder and formed into spherical beads. The engineered form sorbent retained the characteristic surface area and microporosity indicative of mordenite powder. The sorbent was evaluated for krypton adsorption capacities utilizing thermal swing operations achieving capacities of 100 mmol of krypton per kilogram of sorbent at a temperature of 191 K. A krypton adsorption isotherm was also obtained at 191 K with varying krypton feed gas concentrations. Adsorption/desorption cycling effects were also evaluated with results indicating that the sorbent experienced no decrease in krypton capacity throughout testing.

  11. Isolation of the toluene degrading bacteria and application to the biotrickling filtration system of off-gas treatment

    SciTech Connect

    Yamashita, Shigeki

    1999-07-01

    The period of acclimation in biotrickling filtration system was studied using toluene degrading bacteria. Toluene degrading bacteria were isolated from the test biotrickling filtration apparatus used for the degradation of toluene off-gas. Five colonies found in an agar culture medium were identified to be toluene degrading bacteria; one was classified Acinetobacter genospecies 10 and the other four were Rhodococcus erythropolis. The count of the toluene degrading bacteria was 5.6 x 10 to the power 8th Colony Forming Units/ml-packing space. The toluene elimination activity was found to be 7.4 and 2.0 mg-toluene/g-dry cell/min for colony {number{underscore}sign}1 and colony {number{underscore}sign}2, respectively, using batch vial system. They were higher than that obtained when the original sludge in the test biotrickling filtration apparatus was applied to the same system. The performance of colony {number{underscore}sign}1 was also tested by the test biotrickling filtration system. Urethane foam, which constituted a lattice-like structure internally, was used as the microbial carrier. The artificial off-gas of 100ppm toluene/air was prepared with reagent grade chemical. The space velocity (versus the packed bed) was 100/h. Immediately after the start-up, the removal percentages of toluene was 39%, and it became 84% after two days continuous treatment. This result indicates that addition of colony {number{underscore}sign}1 was thus shown to be an effective means of shortening the acclimation period of a trickle bed biofilter.

  12. Development of mathematical model for simulating biosorption of dissolved metals on Bacillus drentensis immobilized in biocarrier beads

    NASA Astrophysics Data System (ADS)

    Nam, J.; Wang, S.; Lee, M.

    2012-12-01

    Biocarrier beads with dead biomass, Bacillus drentensis, immobilized in polymer polysulfone were synthesized to remove heavy metals from wastewater. To identify the sorption mechanisms and theoretical nature of underlying processes, a series of batch experiments were carried out and a mathematical model was developed to quantify the biosorption of Pb(II) and Cu(II) by the biocarrier beads. A series of mass balance equations for representing mass transfer of metal sorbents in a biocarrier beads and surrounding solution were established and solved using a finite difference method. Major model parameters such as external mass transfer coefficient and maximum sorption capacity, etc. were determined from pseudo-first and second-order kinetic models and Langmuir isotherm model based on kinetic and equilibrium experimental measurements. The model simulation displays reasonable representations of experimental data and implied that the proposed model can be applied to quantitative analysis on biosorption mechanisms by porous granular beads. The simulation results also confirms that the biosorption of heavy metal by the biocarrier beads largely depended on surface adsorption.

  13. Hot Corrosion of Inconel 625 Overlay Weld Cladding in Smelting Off-Gas Environment

    NASA Astrophysics Data System (ADS)

    Mohammadi Zahrani, E.; Alfantazi, A. M.

    2013-10-01

    Degradation mechanisms and hot corrosion behavior of weld overlay alloy 625 were studied. Phase structure, morphology, thermal behavior, and chemical composition of deposited salt mixture on the weld overlay were characterized utilizing XRD, SEM/EDX, DTA, and ICP/OES, respectively. Dilution level of Fe in the weldment, dendritic structure, and degradation mechanisms of the weld were investigated. A molten phase formed on the weld layer at the operating temperature range of the boiler, which led to the hot corrosion attack in the water wall and the ultimate failure. Open circuit potential and weight-loss measurements and potentiodynamic polarization were carried out to study the hot corrosion behavior of the weld in the simulated molten salt medium at 873 K, 973 K, and 1073 K (600 °C, 700 °C, and 800 °C). Internal oxidation and sulfidation plus pitting corrosion were identified as the main hot corrosion mechanisms in the weld and boiler tubes. The presence of a significant amount of Fe made the dendritic structure of the weld susceptible to preferential corrosion. Preferentially corroded (Mo, Nb)-depleted dendrite cores acted as potential sites for crack initiation from the surface layer. The penetration of the molten phase into the cracks accelerated the cracks' propagation mainly through the dendrite cores and further crack branching/widening.

  14. The effect of feed water dissolved organic carbon concentration and composition on organic micropollutant removal and microbial diversity in soil columns simulating river bank filtration.

    PubMed

    Bertelkamp, C; van der Hoek, J P; Schoutteten, K; Hulpiau, L; Vanhaecke, L; Vanden Bussche, J; Cabo, A J; Callewaert, C; Boon, N; Löwenberg, J; Singhal, N; Verliefde, A R D

    2016-02-01

    This study investigated organic micropollutant (OMP) biodegradation rates in laboratory-scale soil columns simulating river bank filtration (RBF) processes. The dosed OMP mixture consisted of 11 pharmaceuticals, 6 herbicides, 2 insecticides and 1 solvent. Columns were filled with soil from a RBF site and were fed with four different organic carbon fractions (hydrophilic, hydrophobic, transphilic and river water organic matter (RWOM)). Additionally, the effect of a short-term OMP/dissolved organic carbon (DOC) shock-load (e.g. quadrupling the OMP concentrations and doubling the DOC concentration) on OMP biodegradation rates was investigated to assess the resilience of RBF systems. The results obtained in this study imply that - in contrast to what is observed for managed aquifer recharge systems operating on wastewater effluent - OMP biodegradation rates are not affected by the type of organic carbon fraction fed to the soil column, in case of stable operation. No effect of a short-term DOC shock-load on OMP biodegradation rates between the different organic carbon fractions was observed. This means that the RBF site simulated in this study is resilient towards transient higher DOC concentrations in the river water. However, a temporary OMP shock-load affected OMP biodegradation rates observed for the columns fed with the river water organic matter (RWOM) and the hydrophilic fraction of the river water organic matter. These different biodegradation rates did not correlate with any of the parameters investigated in this study (cellular adenosine triphosphate (cATP), DOC removal, specific ultraviolet absorbance (SUVA), richness/evenness of the soil microbial population or OMP category (hydrophobicity/charge). PMID:26432535

  15. Off-Gas Generation Rate during Chemical Cleaning Operations at the Savannah River Site - 12499

    SciTech Connect

    Wiersma, Bruce J.; Subramanian, Karthik H.; Ketusky, Edward T.

    2012-07-01

    The enhanced chemical cleaning process (ECC) is being developed at the Savannah River Site (SRS) to remove the residual radioactive sludge heel that remains in a liquid waste storage tank. Oxalic acid is the chemical agent utilized for this purpose. However, the acid also corrodes the carbon steel tank wall and cooling coils. If the oxalic acid has little interaction with the sludge, hydrogen gas could conceivably evolve at cathodic areas due to the corrosion of the carbon steel. Scenarios where hydrogen evolution could occur during ECC include the initial filling of the tank prior to agitation and near the end of the process when there is little or no sludge present. The purpose of this activity was to provide a bounding estimate for the hydrogen generation rate during the ECC process. Sealed vessel coupon tests were performed to estimate the hydrogen generation rate due to corrosion of carbon steel by oxalic acid. These tests determined the maximum instantaneous hydrogen generation rate, the rate at which the generation rate decays, and the total hydrogen generated. The tests were performed with polished ASTM A285 Grade C carbon steel coupons. This steel is representative of the Type I and II waste tanks at SRS. Bounding conditions were determined for the solution environment. The oxalic acid concentration was 2.5 wt.% and the test temperature was 75 deg. C. The test solution was agitated and contained no sludge simulant. Duplicate tests were performed and showed excellent reproducibility for the hydrogen generation rate and total hydrogen generated. The results showed that the hydrogen generation rate was initially high, but decayed rapidly within a couple of days. A statistical model was developed to predict the instantaneous hydrogen generation rate as a function of exposure time by combining both sets of data. An upper bound on the maximum hydrogen generation rate was determined from the upper 95% confidence limit. The upper bound limit on the maximum

  16. TREATMENT TANK OFF-GAS TESTING FOR THE ENHANCED CHEMICAL CLEANING PROCESS

    SciTech Connect

    Wiersma, B.

    2011-08-29

    The purpose of this activity was to provide a bounding estimate of the volume of hydrogen gas generated during Enhanced Chemical Cleaning (ECC) of residual sludge remaining in a Type I or Type II treatment tank as well as to provide results independent of the sludge volume in the waste tank to be cleaned. Previous testing to support Chemical Cleaning was based on a 20:1 oxalic acid to sludge ratio. Hydrogen gas evolution is the primary safety concern. Sealed vessel coupon tests were performed to estimate the hydrogen generation rate due to corrosion of carbon steel by 2.5 wt.% oxalic acid. These tests determined the maximum instantaneous hydrogen generation rate, the rate at which the generation rate decays, and the total hydrogen generated. These values were quantified based on a small scale methodology similar to the one described in WSRC-STI-2007-00209, Rev. 0. The measured rates support identified Safety Class functions. The tests were performed with ASTM A285 Grade C carbon steel coupons. Bounding conditions were determined for the solution environment. The oxalic acid concentration was 2.5 wt.% and the test temperature was 75 C. The test solution was agitated and contained no sludge simulant. Duplicate tests were performed and showed excellent reproducibility for the hydrogen generation rate and total hydrogen generated. The results showed that the hydrogen generation rate was initially high, but decayed rapidly within a couple of days. A statistical model was developed to predict the instantaneous hydrogen generation rate as a function of exposure time by combining both sets of data. An upper bound on the maximum hydrogen generation rate was determined from the upper 95% confidence limit. The upper bound confidence limit for the hydrogen generation rate is represented by the following equation. ln (G{sub v}) = -8.22-0.0584 t + 0.0002 t{sup 2}. This equation should be utilized to estimate the instantaneous hydrogen generation rate per unit surface area, G

  17. Materials evaluation in the WERF (Waste Experimental Reduction Facility) low-level radioactive waste incinerator off-gas system

    SciTech Connect

    Smolik, G.R.; Dalton, J.D.

    1988-08-01

    Performances of alloys in a low-level radioactive, combustible waste incinerator were evaluated. Test coupons and an extracted heat exchanger tube were examined to provide information on alloy behavior in the off-gas system of this facility. Type 316 stainless steel, the alloy of which the heat exchanger is constructed, was most extensively examined. Coupons exposed upstream of the heat exchanger exhibited high temperature corrosion rates of /approximately/100 mpy (incinerator operation time). The rate observed from the heat exchanger tube was lower, /approximately/25 mpy. A 10 year lifetime would be expected based upon this mode of attack and continued similar operating parameters and waste composition. Other alloys were tested to identify potential replacement candidates. Alloys displaying lower metal loss rates at the location upstream of the heat exchanger included HDA 8727 (7 mpy), Alloy 800H (37 mpy), Haynes 230 (50 mpy), and Type 310 stainless steel (63 mpy). The relatively long term exposures (spanning over 4250 hrs of operation) and controlled waste composition makes this information pertinent to the waste incineration community as well as the WERF program. 15 refs., 18 figs., 11 tabs.

  18. Novel Sorbent Development and Evaluation for the Capture of Krypton and Xenon from Nuclear Fuel Reprocessing Off-Gas Streams

    SciTech Connect

    Troy G. Garn; Mitchell R. Greenhalgh; Jack D. Law

    2013-10-01

    The release of volatile radionuclides generated during Used Nuclear Fuel reprocessing in the US will most certainly need to be controlled to meet US regulatory emission limits. A US DOE sponsored Off-Gas Sigma Team has been tasked with a multi-lab collaborative research and development effort to investigate and evaluate emissions and immobilization control technologies for the volatile radioactive species generated from commercial Used Nuclear Fuel (UNF) Reprocessing. Physical Adsorption technology is a simpler and potential economical alternative to cryogenic distillation processes that can be used for the capture of krypton and xenon and has resulted in a novel composite sorbent development procedure using synthesized mordenite as the active material. Utilizing the sorbent development procedure, INL sigma team members have developed two composite sorbents that have been evaluated for krypton and xenon capacities at ambient and 191 K temperature using numerous test gas compositions. Adsorption isotherms have been generated to predict equilibration and maximum capacities enabling modeling to support process equipment scale-up.

  19. Novel Sorbent Development and Evaluation for the Capture of Krypton and Xenon from Nuclear Fuel Reprocessing Off-Gas Streams

    SciTech Connect

    Troy G. Garn; Mitchell R. Greenhalgh; Jack D. Law

    2013-09-01

    The release of volatile radionuclides generated during Used Nuclear Fuel reprocessing in the US will most certainly need to be controlled to meet US regulatory emission limits. A US DOE sponsored Off-Gas Sigma Team has been tasked with a multi-lab collaborative research and development effort to investigate and evaluate emissions and immobilization control technologies for the volatile radioactive species generated from commercial Used Nuclear Fuel (UNF) Reprocessing. Physical Adsorption technology is a simpler and potential economical alternative to cryogenic distillation processes that can be used for the capture of krypton and xenon and has resulted in a novel composite sorbent development procedure using synthesized mordenite as the active material. Utilizing the sorbent development procedure, INL sigma team members have developed two composite sorbents that have been evaluated for krypton and xenon capacities at ambient and 191 K temperature using numerous test gas compositions. Adsorption isotherms have been generated to predict equilibration and maximum capacities enabling modeling to support process equipment scale-up.

  20. Novel sorbent development and evaluation for the capture of krypton and xenon from nuclear fuel reprocessing off-gas stream

    SciTech Connect

    Garn, T.G.; Greenhalgh, M.R.; Law, J.D.

    2013-07-01

    The release of volatile radionuclides generated during Used Nuclear Fuel reprocessing in the US will most certainly need to be controlled to meet US regulatory emission limits. A US DOE sponsored Off-Gas Sigma Team has been tasked with a multi-lab collaborative research and development effort to investigate and evaluate emissions and immobilization control technologies for the volatile radioactive species generated from commercial Used Nuclear Fuel (UNF) Reprocessing. Physical Adsorption technology is a simpler and potential economical alternative to cryogenic distillation processes that can be used for the capture of krypton and xenon and has resulted in a novel composite sorbent development procedure using synthesized mordenite as the active material. Utilizing the sorbent development procedure, Idaho National Laboratory sigma team members have developed two composite sorbents that have been evaluated for krypton and xenon capacities at ambient and 191 K temperature using numerous test gas compositions. Adsorption isotherms have been generated to predict equilibration and maximum capacities enabling modeling to support process equipment scale-up. (authors)

  1. Peer review panel summary report for technical determination of mixed waste incineration off-gas systems for Rocky Flats; Appendix A

    SciTech Connect

    1992-12-31

    A Peer Review Panel was convened on September 15-17, 1992 in Boulder, Co. The members of this panel included representatives from DOE, EPA, and DOE contractors along with invited experts in the fields of air pollution control and waste incineration. The primary purpose of this review panel was to make a technical determination of a hold, test and release off gas capture system should be implemented in the proposed RF Pland mixed waste incineration system; or if a state of the art continuous air pollution control and monitoring system should be utilized as the sole off-gas control system. All of the evaluations by the panel were based upon the use of the fluidized bed unit proposed by Rocky Flats and cannot be generalized to other systems.

  2. Field demonstration for bioremediation treatment: Technology demonstration of soil vapor extraction off-gas at McClellan Air Force Base. Final report November 1997--April 1998

    SciTech Connect

    Magar, V.S.; Tonga, P.; Webster, T.; Drescher, E.

    1999-01-12

    McClellan Air Force Base (AFB) is a National Test Location designated through the Strategic Environmental Research and Development Program (SERDP), and was selected as the candidate test site for a demonstration of soil vapor extraction (SVE) off-gas treatment technology. A two-stage reactor system was employed for the treatment of the off-gas. The biological treatment was conducted at Operable Unit (OU) D Site S, located approximately 400 ft southwest of Building 1093. The SVE system at this area normally operates at a nominal volumetric flowrate of approximately 500 to 600 standard cubic feet per minute (scfm). The contaminated air stream from the SVE system that was fed to the reactor system operated at a flowrate of 5 to 10 scfm. The two-stage reactor system consisted of a fixed-film biofilter followed by a completely mixed (by continuous stirring), suspended-growth biological reactor. This reactor configuration was based on a review of the literature, on characterization of the off-gas from the SVE system being operated at McClellan AFB, and on the results of the laboratory study conducted by Battelle and Envirogen for this study.

  3. AFCI Coupled End-to-End Research,Development and Demonstration Project: Integrated Off-gas Treatment System Design and Initial Performance - 9226

    SciTech Connect

    Jubin, Robert Thomas; Patton, Bradley D; Ramey, Dan W; Spencer, Barry B

    2009-01-01

    Oak Ridge National Laboratory is conducting a complete, coupled end-to-end (CETE) demonstration of advanced nuclear fuel reprocessing to support the Advanced Fuel Cycle Initiative. This small-scale reprocessing operation provides a unique opportunity to test integrated off-gas treatment systems designed to recover the primary volatile fission and activation products (H-3, C-14, Kr-85, and I-139) released from the spent nuclear fuel (SNF). The CETE project will demonstrate an advanced head-end process, referred to as voloxidation, designed to condition the SNF, separate the SNF from the cladding, and release tritium contained in the fuel matrix. The off-gas from the dry voloxidation process as well as from the more traditional fuel dissolution process will be treated separately and the volatile components recovered. This paper provides descriptions of the off-gas treatment systems for both the voloxidation process and for the fuel dissolution process and provides preliminary results from the initial CETE processing runs. Impacts of processing parameters on the relative quantities of volatile components released and recovery efficiencies are evaluated.

  4. The development of an industrial-scale fed-batch fermentation simulation.

    PubMed

    Goldrick, Stephen; Ştefan, Andrei; Lovett, David; Montague, Gary; Lennox, Barry

    2015-01-10

    This paper describes a simulation of an industrial-scale fed-batch fermentation that can be used as a benchmark in process systems analysis and control studies. The simulation was developed using a mechanistic model and validated using historical data collected from an industrial-scale penicillin fermentation process. Each batch was carried out in a 100,000 L bioreactor that used an industrial strain of Penicillium chrysogenum. The manipulated variables recorded during each batch were used as inputs to the simulator and the predicted outputs were then compared with the on-line and off-line measurements recorded in the real process. The simulator adapted a previously published structured model to describe the penicillin fermentation and extended it to include the main environmental effects of dissolved oxygen, viscosity, temperature, pH and dissolved carbon dioxide. In addition the effects of nitrogen and phenylacetic acid concentrations on the biomass and penicillin production rates were also included. The simulated model predictions of all the on-line and off-line process measurements, including the off-gas analysis, were in good agreement with the batch records. The simulator and industrial process data are available to download at www.industrialpenicillinsimulation.com and can be used to evaluate, study and improve on the current control strategy implemented on this facility. PMID:25449107

  5. Dissolver vessel bottom assembly

    DOEpatents

    Kilian, Douglas C.

    1976-01-01

    An improved bottom assembly is provided for a nuclear reactor fuel reprocessing dissolver vessel wherein fuel elements are dissolved as the initial step in recovering fissile material from spent fuel rods. A shock-absorbing crash plate with a convex upper surface is disposed at the bottom of the dissolver vessel so as to provide an annular space between the crash plate and the dissolver vessel wall. A sparging ring is disposed within the annular space to enable a fluid discharged from the sparging ring to agitate the solids which deposit on the bottom of the dissolver vessel and accumulate in the annular space. An inlet tangential to the annular space permits a fluid pumped into the annular space through the inlet to flush these solids from the dissolver vessel through tangential outlets oppositely facing the inlet. The sparging ring is protected against damage from the impact of fuel elements being charged to the dissolver vessel by making the crash plate of such a diameter that the width of the annular space between the crash plate and the vessel wall is less than the diameter of the fuel elements.

  6. Rate and peak concentrations of off-gas emissions in stored wood pellets--sensitivities to temperature, relative humidity, and headspace volume.

    PubMed

    Kuang, Xingya; Shankar, Tumuluru Jaya; Bi, Xiaotao T; Lim, C Jim; Sokhansanj, Shahab; Melin, Staffan

    2009-11-01

    Wood pellets emit CO, CO(2), CH(4), and other volatiles during storage. Increased concentration of these gases in a sealed storage causes depletion of concentration of oxygen. The storage environment becomes toxic to those who operate in and around these storages. The objective of this study was to investigate the effects of temperature, moisture, and the relative size of storage headspace on emissions from wood pellets in an enclosed space. Twelve 10-l plastic containers were used to study the effects of headspace ratio (25, 50, and 75% of container volume) and temperatures (10-50 degrees C). Another eight containers were set in uncontrolled storage relative humidity (RH) and temperature. Concentrations of CO(2), CO, and CH(4) were measured by gas chromatography (GC). The results showed that emissions of CO(2), CO, and CH(4) from stored wood pellets are more sensitive to storage temperature than to RH and the relative volume of headspace. Higher peak emission factors are associated with higher temperatures. Increased headspace volume ratio increases peak off-gas emissions because of the availability of oxygen associated with pellet decomposition. Increased RH in the enclosed container increases the rate of off-gas emissions of CO(2), CO, and CH(4) and oxygen depletion. PMID:19656803

  7. Rate and peak concentrations of off-gas emissions in stored wood pellets sensitivities to temperature, relative humidity, and headspace volume

    SciTech Connect

    Kuang, Xingya; Shankar, T.J.; Bi, X.T.; Lim, C. Jim; Sokhansanj, Shahabaddine; Melin, Staffan

    2009-08-01

    Wood pellets emit CO, CO2, CH4 and other volatiles during storage. Increased concentration of these gases in a sealed storage causes depletion of concentration of oxygen. The storage environment becomes toxic to those who operate in and around these storages. The objective of this study was to investigate the effects of temperature, moisture and storage headspace on emissions from wood pellets in an enclosed space. Twelve 10-liter plastic containers were used to study the effects of headspace ratio (25%, 50%, and 75% of container volume) and temperatures (10-50oC). Another eight containers were set in uncontrolled storage relative humidity and temperature. Concentrations of CO2, CO and CH4 were measured by a gas chromatography (GC). The results showed that emissions of CO2, CO and CH4 from stored wood pellets are most sensitive to storage temperature. Higher peak emission factors are associated with higher temperatures. Increased headspace volume ratio increases peak off-gas emissions because of the availability of oxygen for pellet decomposition. Increased relative humidity in the enclosed container increases the rate of off-gas emissions of CO2, CO and CH4 and oxygen depletion.

  8. Efficient carbon dioxide utilization and simultaneous hydrogen enrichment from off-gas of acetone-butanol-ethanol fermentation by succinic acid producing Escherichia coli.

    PubMed

    He, Aiyong; Kong, Xiangping; Wang, Chao; Wu, Hao; Jiang, Min; Ma, Jiangfeng; Ouyang, Pingkai

    2016-08-01

    The off-gas from acetone-butanol-ethanol (ABE) fermentation was firstly used to be CO2 source (co-substrate) for succinic acid production. The optimum ratio of H2/CO2 indicated higher CO2 partial pressures with presence of H2 could enhance C4 pathway flux and reductive product productivity. Moreover, when an inner recycling bioreactor was used for CO2 recycling at a high total pressure (0.2Mpa), a maximum succinic acid concentration of 65.7g·L(-1) was obtained, and a productivity of 0.76g·L(-1)·h(-1) and a high yield of 0.86g·g(-1) glucose were achieved. Furthermore, the hydrogen content was simultaneously enriched to 92.7%. These results showed one successful attempt to reuse the off-gas of ABE fermentation which can be an attractive CO2 source for succinic acid production. PMID:27142628

  9. Modifying the dissolved-in-water type natural gas field simulation model based on the distribution of estimated Young's modulus for the Kujukuri region, Japan

    NASA Astrophysics Data System (ADS)

    Nakagawa, T.; Matsuyama, R.; Adachi, M.; Kuroshima, S.; Ogatsu, T.; Adachi, R.

    2015-11-01

    A simulation model, which covers the part of Southern-Kanto natural gas field in Chiba prefecture, was developed to perform studies and make predictions of land subsidence. However, because large differences between simulated and measured subsidence occurred in the northern modeled area of the gas field, the model was modified with an estimated Young's modulus distribution. This distribution was estimated by the yield value distribution and the correlation of yield value with Young's modulus. Consequently, the simulated subsidence in the north area was improved to some extent.

  10. The interplay between the paracetamol polymorphism and its molecular structures dissolved in supercritical CO2 in contact with the solid phase: In situ vibration spectroscopy and molecular dynamics simulation analysis.

    PubMed

    Oparin, Roman D; Moreau, Myriam; De Walle, Isabelle; Paolantoni, Marco; Idrissi, Abdenacer; Kiselev, Michael G

    2015-09-18

    The aim of this paper is to characterize the distribution of paracetamol conformers which are dissolved in a supercritical CO2 phase being in equilibrium with their corresponding crystalline form. The quantum calculations and molecular dynamics simulations were used in order to characterize the structure and analyze the vibration spectra of the paracetamol conformers in vacuum and in a mixture with CO2 at various thermodynamic state parameters (p,T). The metadynamics approach was applied to efficiently sample the various conformers of paracetamol. Furthermore, using in situ IR spectroscopy, the conformers that are dissolved in supercritical CO2 were identified and the evolution of the probability of their presence as a functions of thermodynamic condition was quantified while the change in the crystalline form of paracetamol have been monitored by DSC, micro IR and Raman techniques. The DSC analysis as well as micro IR and Raman spectroscopic studies of the crystalline paracetamol show that the subsequent heating up above the melting temperature of the polymorph I of paracetamol and the cooling down to room temperature in the presence of supercritical CO2 induces the formation of polymorph II. The in situ IR investigation shows that two conformers (Conf. 1 and Conf. 2) are present in the phase of CO2 while conformer 3 (Conf. 3) has a high probability to be present after re-crystallization. PMID:26028160

  11. Sequence and transcriptional analysis of the genes responsible for curdlan biosynthesis in Agrobacterium sp. ATCC 31749 under simulated dissolved oxygen gradients conditions.

    PubMed

    Zhang, Hong-Tao; Zhan, Xiao-Bei; Zheng, Zhi-Yong; Wu, Jian-Rong; Yu, Xiao-Bin; Jiang, Yun; Lin, Chi-Chung

    2011-07-01

    Expression at the mRNA level of ten selected genes in Agrobacterium sp. ATCC 31749 under various dissolved oxygen (DO) levels during curdlan fermentation related to electron transfer chain (ETC), tricarboxylic acid (TCA) cycle, peptidoglycan/lipopolysaccharide biosynthesis, and uridine diphosphate (UDP)-glucose biosynthesis were determined by qRT-PCR. Experiments were performed at DO levels of 30%, 50%, and 75%, as well as under low-oxygen conditions. The effect of high cell density on transcriptional response of the above genes under low oxygen was also studied. Besides cytochrome d (cyd A), the transcription levels of all the other genes were increased at higher DO and reached maximum at 50% DO. Under 75% DO, the transcriptional levels of all the genes were repressed. In addition, transcription levels of icd, sdh, cyo A, and fix N genes did not exhibit significant fluctuation with high cell density culture under low oxygen. These results suggested a mechanism for DO regulation of curdlan synthesis through regulation of transcriptional levels of ETCs, TCA, and UDP-glucose synthesis genes during curdlan fermentation. To our knowledge, this is the first report that DO concentration apparently regulates curdlan biosynthesis in Agrobacterium sp. ATCC 31749 providing essential lead for the optimization of the fermentation at the industrial scale. PMID:21472535

  12. Simulation of dissolved oxygen and biochemical oxygen demand, Plantation Canal, Broward County, Florida with an evaluation of the QUAL-I model for use in south Florida

    USGS Publications Warehouse

    Russo, Thomas N.; McQuivey, Raul S.

    1975-01-01

    A mathematical model; QUAL-I, developed by the Texas Water Development Board, was evaluated as a management tool in predicting the spatial and temporal distribution of dissolved oxygen and biochemical oxygen demand in Plantation Canal. Predictions based on the QUAL-I model, which was verified only against midday summer-flow conditions, showed that improvement of quality of inflows from sewage treatment plants and use of at least 130 cubic feet per second of dilution water would improve water quality in the canal significantly. The model was not fully amenable to use on Plantation Canal because: (1) it did not consider photosynthetic production, nitrification, and benthic oxygen demand as sources and sinks of oxygen; (2) the model assumptions of complete mixing, transport, and steady state were not met; and (3) the data base was inadequate because it consisted of only one set of data for each case. However, it was felt that meaningful results could be obtained for some sets of conditions. (Woodard-USGS)

  13. Investigation of the effects of beam scattering and beam wandering on laser beams passing thorough the off-gas duct of an Electric Arc Furnace

    NASA Astrophysics Data System (ADS)

    Alikhanzadeh, Amirhossein

    The project sets to determine the effects of scattering and beam wandering on light that passes through the off-gas of EAF. The effects of light scattering from metallic dust and beam wandering due to temperature gradient and turbulence in the medium are investigated. Using Matlab, a model was developed based on Mie theory to calculate light transmission when the optical properties are known; most importantly refractive index of the dust as well as incident wavelength, particle size and concentration of the particles per cm 3 of the gas. The model was validated and was used to show that as the particle size parameter increases, the scattering losses decreases. Turbulence and temperature gradients in the air cause the laser beam to change shape. Using a big collection lens can minimize the signal fluctuation caused by the beam wandering. A thorough understanding of these phenomena helps in designing optical sensors in the industry.

  14. Leaching of the residue from the dry off-gas de-dusting and desulfurization process of an iron ore sinter plant

    NASA Astrophysics Data System (ADS)

    Lanzerstorfer, Christof; Xu, Qi; Neuhold, Robert

    2015-02-01

    The residue from a second-stage dry sinter plant off-gas cleaning process contains both the fine dust from the sinter plant and the sorbent used. Recycling of the material that is usually handled by landfills to the sinter plant feed is not possible because of its chloride content. Leaching of the chlorides allow the recycling of remaining solids. The saline leachate produced contains some heavy metals and must be treated before it is discharged into the sea. In laboratory experiments, leaching tests with the subsequent treatment of the leachate were conducted. After the process was optimized, all heavy-metal concentrations were below the permissible values. The optimum treatment conditions for heavy-metal precipitation were observed to be the filtration of the suspended solids followed by the dosing of liquid with lime milk (pH 10) and the subsequent precipitation using sodium sulfide.

  15. Formulation and in vivo human bioavailability of dissolving tablets containing a self-nanoemulsifying itraconazole solid dispersion without precipitation in simulated gastrointestinal fluid.

    PubMed

    Piao, Zong-Zhu; Choe, Jae-Seung; Oh, Kyung Teak; Rhee, Yun-Seok; Lee, Beom-Jin

    2014-01-23

    To investigate the performance of a solid-state self-nanoemulsifying system with no precipitation in gastric and intestinal fluid, itraconazole (ITZ) was selected as a model drug because of its practically insoluble nature in intestinal fluid. A self-nanoemulsifying ITZ solid dispersion (SNESD) system was prepared as follows: (1) establishment of self-nanoemulsifying composition via the hot melting method, (2) solidification with fumed silicon dioxide (Aerosil 300) via adsorption to prepare SNESD and (3) preparation of a directly compressible tablet containing SNESD. This SNESD was easily formulated in the form of a dissolving tablet and provided a favourable nanoemulsifying microenvironment with no precipitation in the testing media. The SNESD and SNESD-loaded tablet displayed highly enhanced dissolution via nanomisation (266.8 nm and 258.3 nm at 60 min and 120 min, respectively), whereas the drug alone or a reference ITZ Sporanox® capsule displayed very low dissolution and precipitated immediately in intestinal fluid. Drug precipitation in intestinal fluid may affect the in vivo performance of poorly soluble weakly basic drugs and was estimated according to the crystal growth theory. The superdisintegrant and surfactant in the formulation of the tablet were very crucial to the dissolution of the SNESD-loaded tablet. The drug contents and dissolution rates of the SNESD-loaded tablets were also stable during storage in terms of dissolution and drug content. The SNESD-loaded tablet displayed significantly increased oral bioavailability in healthy human volunteers compared with the reference Sporanox® capsule. The current solid-state SNESD-loaded tablet could provide an alternative to liquid-based emulsifying preparations for various poorly water-soluble drugs without precipitation in testing media. PMID:24012590

  16. Simulated passage through a modified Kaplan turbine pressure regime: A supplement to "Laboratory Studies of the Effects of Pressure and Dissolved Gas Supersaturation on Turbine-Passed Fish"

    SciTech Connect

    Abernethy, C. S.; Amidan, B. G.; Cada, G. F.

    2002-04-01

    A previous test series (Abernethy et al. 2001) evaluated the effects of passage through a Kaplan turbine under the “worst case” pressure conditions. For this series of tests, pressure changes were modified to simulate passage through a Kaplan turbine under a more “fish-friendly” mode of operation. The results were compared to results from Abernethy et al. (2001). These data indicate that altered operating conditions that raise the nadir (low point) of the turbine passage pressure regime could reduce the injury and mortality rates of fish during turbine passage. Fall Chinook salmon were not injured or killed when subjected to the modified pressure scenario. Bluegills were more sensitive to pressure effects than fall Chinook salmon, but injury and mortality rates were lower under the modified Kaplan pressure regime. This improvement was particularly significant among fish that were acclimated to greater water pressures (traveling at greater depth).

  17. DEVELOPMENT OF AN ANTIFOAM TRACKING SYSTEM AS AN OPTION TO SUPPORT THE MELTER OFF-GAS FLAMMABILITY CONTROL STRATEGY AT THE DWPF

    SciTech Connect

    Edwards, T.; Lambert, D.

    2014-08-27

    The Savannah River National Laboratory (SRNL) has been working with the Savannah River Remediation (SRR) Defense Waste Processing Facility (DWPF) in the development and implementation of an additional strategy for confidently satisfying the flammability controls for DWPF’s melter operation. An initial strategy for implementing the operational constraints associated with flammability control in DWPF was based upon an analytically determined carbon concentration from antifoam. Due to the conservative error structure associated with the analytical approach, its implementation has significantly reduced the operating window for processing and has led to recurrent Slurry Mix Evaporator (SME) and Melter Feed Tank (MFT) remediation. To address the adverse operating impact of the current implementation strategy, SRR issued a Technical Task Request (TTR) to SRNL requesting the development and documentation of an alternate strategy for evaluating the carbon contribution from antifoam. The proposed strategy presented in this report was developed under the guidance of a Task Technical and Quality Assurance Plan (TTQAP) and involves calculating the carbon concentration from antifoam based upon the actual mass of antifoam added to the process assuming 100% retention. The mass of antifoam in the Additive Mix Feed Tank (AMFT), in the Sludge Receipt and Adjustment Tank (SRAT), and in the SME is tracked by mass balance as part of this strategy. As these quantities are monitored, the random and bias uncertainties affecting their values are also maintained and accounted for. This report documents: 1) the development of an alternate implementation strategy and associated equations describing the carbon concentration from antifoam in each SME batch derived from the actual amount of antifoam introduced into the AMFT, SRAT, and SME during the processing of the batch. 2) the equations and error structure for incorporating the proposed strategy into melter off-gas flammability assessments

  18. Development and Testing of the Advanced CHP System Utilizing the Off-Gas from the Innovative Green Coke Calcining Process in Fluidized Bed

    SciTech Connect

    Chudnovsky, Yaroslav; Kozlov, Aleksandr

    2013-08-15

    Green petroleum coke (GPC) is an oil refining byproduct that can be used directly as a solid fuel or as a feedstock for the production of calcined petroleum coke. GPC contains a high amount of volatiles and sulfur. During the calcination process, the GPC is heated to remove the volatiles and sulfur to produce purified calcined coke, which is used in the production of graphite, electrodes, metal carburizers, and other carbon products. Currently, more than 80% of calcined coke is produced in rotary kilns or rotary hearth furnaces. These technologies provide partial heat utilization of the calcined coke to increase efficiency of the calcination process, but they also share some operating disadvantages. However, coke calcination in an electrothermal fluidized bed (EFB) opens up a number of potential benefits for the production enhancement, while reducing the capital and operating costs. The increased usage of heavy crude oil in recent years has resulted in higher sulfur content in green coke produced by oil refinery process, which requires a significant increase in the calcinations temperature and in residence time. The calorific value of the process off-gas is quite substantial and can be effectively utilized as an “opportunity fuel” for combined heat and power (CHP) production to complement the energy demand. Heat recovered from the product cooling can also contribute to the overall economics of the calcination process. Preliminary estimates indicated the decrease in energy consumption by 35-50% as well as a proportional decrease in greenhouse gas emissions. As such, the efficiency improvement of the coke calcinations systems is attracting close attention of the researchers and engineers throughout the world. The developed technology is intended to accomplish the following objectives: - Reduce the energy and carbon intensity of the calcined coke production process. - Increase utilization of opportunity fuels such as industrial waste off-gas from the novel

  19. ADDING REALISM TO NUCLEAR MATERIAL DISSOLVING ANALYSIS

    SciTech Connect

    Williamson, B.

    2011-08-15

    Two new criticality modeling approaches have greatly increased the efficiency of dissolver operations in H-Canyon. The first new approach takes credit for the linear, physical distribution of the mass throughout the entire length of the fuel assembly. This distribution of mass is referred to as the linear density. Crediting the linear density of the fuel bundles results in using lower fissile concentrations, which allows higher masses to be charged to the dissolver. Also, this approach takes credit for the fact that only part of the fissile mass is wetted at a time. There are multiple assemblies stacked on top of each other in a bundle. On average, only 50-75% of the mass (the bottom two or three assemblies) is wetted at a time. This means that only 50-75% (depending on operating level) of the mass is moderated and is contributing to the reactivity of the system. The second new approach takes credit for the progression of the dissolving process. Previously, dissolving analysis looked at a snapshot in time where the same fissile material existed both in the wells and in the bulk solution at the same time. The second new approach models multiple consecutive phases that simulate the fissile material moving from a high concentration in the wells to a low concentration in the bulk solution. This approach is more realistic and allows higher fissile masses to be charged to the dissolver.

  20. FINAL REPORT DM1200 TESTS WITH AZ 101 HLW SIMULANTS VSL-03R3800-4 REV 0 2/17/04

    SciTech Connect

    KRUGER AA; MATLACK KS; BARDAKCI T; D'ANGELO NA; GONG W; KOT WK; PEGG IL

    2011-12-29

    This report documents melter and off-gas performance results obtained on the DM 1200 HLW Pilot Melter during processing of simulated HLW AZ-101 feed. The principal objectives of the DM1200 melter testing were to determine the achievable glass production rates for simulated HLW AZ-101 feed; determine the effect of bubbling rate and feed solids content on production rate; characterize melter off-gas emissions; characterize the performance of the prototypical off-gas system components as well as their integrated performance; characterize the feed, glass product, and off-gas effluents; and to perform pre- and post-test inspections of system components. The test objectives (including test success criteria), along with how they were met, are outlined in a table.

  1. Influence of pH, inorganic anions, and dissolved organic matter on the photolysis of antimicrobial triclocarban in aqueous systems under simulated sunlight irradiation.

    PubMed

    Ding, Shi-Ling; Wang, Xi-Kui; Jiang, Wen-Qiang; Zhao, Ru-Song; Shen, Ting-Ting; Wang, Chen; Wang, Xia

    2015-04-01

    The photolysis of the antimicrobial triclocarban (TCC) in aqueous systems under simulated sunlight irradiation was studied. The effects of several abiotic parameters, including solution pH, initial TCC concentration, presence of natural organic matter, and most common inorganic anions in surface waters, were investigated. The results show that the photolysis of TCC followed pseudo-first-order kinetics. The TCC photolysis rate constant increased with increasing solution pH and decreasing the initial TCC concentration. Compared with the TCC photolysis in pure water, the presence of aqueous bicarbonate, nitrate, humic acids, and its sodium salt decreased the TCC photolysis rate, but fulvic acid increased the TCC photolysis rate. The electron spin resonance and reactive oxygen species scavenging experiments indicated that TCC may undergo two different types of phototransformation reactions: direct photolysis and energy transfer to generate (1)O2. The main degradation products were tentatively identified by gas chromatography interfaced with mass spectrometry (GC-MS), and a possible degradation pathway was also proposed. PMID:25354431

  2. Customized design of electronic noses placed on top of air-lift bioreactors for in situ monitoring the off-gas patterns.

    PubMed

    Rosi, Pablo E; Miscoria, Silvia A; Bernik, Delia L; Martín Negri, R

    2012-06-01

    A specially designed electronic nose was coupled to an air-lift bioreactor in order to perform on-line monitoring of released vapors. The sensor array was placed at the top of the bioreactor sensing the headspace in equilibrium with the evolving liquor at any time without the need of aspiration and pumping of gases into a separated sensor chamber. The device was applied to follow the off-gas of a bioreactor with Acidithiobacillus thiooxidans grown on beds of elemental sulfur under aerobic conditions. Evolution was monitored by acid titration, pH and optical density measurements. The electronic nose was capable to differentiate each day of reactor evolution since inoculation within periods marked off culture medium replacements using multivariate data analysis. Excellent discrimination was obtained indicating the potentiality for on-line monitoring in non-perturbed bioreactors. The prospects for electronic nose/bioreactor merging are valuable for whatever the bacterial strain or consortium used in terms of scent markers to monitor biochemical processes. PMID:22212349

  3. Transport of dissolved gas and its ecological impact after a gas release from deepwater.

    PubMed

    Wimalaratne, Malinda R; Yapa, Poojitha D; Nakata, Kisaburo; Premathilake, Lakshitha T

    2015-11-15

    Previous models on simulating gas releases in deepwater were not focused on the dissolved component and its impact on water quality. This paper presents a new model developed for simulating the transport/spread of dissolved methane from an underwater release and its impact on dissolved oxygen in ambient water. Methane dissolves into ambient water from gas phase, direct from hydrate phase, and from dissociating hydrates formed earlier. Dissolved methane affects the dissolved oxygen levels in ambient water due to microbial interaction and possible direct absorption of oxygen into methane bubbles. We use new model simulations of Deepspill field experiments to compare with instantaneous profiles which were unpublished until now. The comparisons are very good with a short time lag, but are within the acceptable discrepancy for models for emergency response and contingency planning. Scenario simulations show the effect on dissolved oxygen due to different methane release situations. PMID:26364205

  4. Off gas film cooler cleaner

    DOEpatents

    Dhingra, Hardip S.; Koch, William C.; Burns, David C.

    1997-01-01

    An apparatus for cleaning depositions of particulate matter from the inside of tubular piping while the piping is in use. The apparatus is remote controlled in order to operate in hazardous environments. A housing containing brush and shaft assemblies is mounted on top of the tubular piping. Pneumatic cylinders provide linear motion. A roller nut bearing provides rotary motion. The combined motion causes the brush assembly to rotate as it travels along the tube dislodging particulate matter.

  5. Off gas film cooler cleaner

    DOEpatents

    Dhingra, H.S.; Koch, W.C.; Burns, D.C.

    1997-08-26

    An apparatus is described for cleaning depositions of particulate matter from the inside of tubular piping while the piping is in use. The apparatus is remote controlled in order to operate in hazardous environments. A housing containing brush and shaft assemblies is mounted on top of the tubular piping. Pneumatic cylinders provide linear motion. A roller nut bearing provides rotary motion. The combined motion causes the brush assembly to rotate as it travels along the tube dislodging particulate matter. 5 figs.

  6. Startup and initial operation of a DFGD and pulse jet fabric filter system on Cokenergy's Indiana Harbor coke oven off gas system

    SciTech Connect

    Morris, W.J.; Gansley, R.R.; Schaddell, J.G.

    1999-07-01

    This paper describes the design, initial operation and performance testing of a Dry Flue Gas Desulfurization (DFGD) and Modular Pulse Jet Fabric Filter (MPJFF) system installed at Cokenergy's site in East Chicago, Indiana. The combined flue gas from the sixteen (16) waste heat recovery boilers is processed by the system to control emissions of sulfur dioxide and particulates. These boilers recover energy from coke oven off gas from Indiana Harbor Coke Company's coke batteries. The DFGD system consists of two 100% capacity absorbers. Each absorber vessel uses a single direct drive rotary atomizer to disperse the lime slurry for SO{sub 2} control. The MPJFF consists of thirty two (32) modules arranged in twin sixteen-compartment (16) units. The initial start up of the DFGD/MPJFF posed special operational issues due to the low initial gas flows through the system as the four coke oven batteries were cured and put in service for the first time. This occurred at approximately monthly intervals beginning in March 1998. A plan was implemented to perform a staged startup of the DFGD and MPJFF to coincide with the staged start up of the coke batteries and waste heat boilers. Operational issues that are currently being addressed include reliability of byproduct removal. Performance testing was conducted in August and September 1998 at the inlet of the system and the outlet stack. During these tests, particulate, SO{sub 2}, SO{sub 3}, and HCI emissions were measured simultaneously at the common DFGD inlet duct and the outlet stack. Measurements were also taken for average lime, water, and power consumption during the tests as well as system pressure losses. These results showed that all guarantee parameters were achieved during the test periods. The initial operation and performance testing are described in this paper.

  7. Method for dissolving plutonium dioxide

    DOEpatents

    Tallent, Othar K.

    1978-01-01

    The fluoride-catalyzed, non-oxidative dissolution of plutonium dioxide in HNO.sub.3 is significantly enhanced in rate by oxidizing dissolved plutonium ions. It is believed that the oxidation of dissolved plutonium releases fluoride ions from a soluble plutonium-fluoride complex for further catalytic action.

  8. The decomposition of vegetation and soil in marginal peat-forming landscapes: climate simulations to quantify gaseous and dissolved carbon fluxes and the effects on peat accumulation and drinking water treatment

    NASA Astrophysics Data System (ADS)

    Ritson, J.; Bell, M.; Clark, J. M.; Graham, N.; Templeton, M.; Brazier, R.; Verhoef, A.; Freeman, C.

    2013-12-01

    Peatlands in the UK represent a large proportion of the soil carbon store, however there is concern that some systems may be switching from sinks to sources of carbon. The accumulation of organic material in peatlands results from the slow rates of decomposition typically occurring in these regions. Climate change may lead to faster decomposition which, if not matched by an equivalent increase in net primary productivity and litter fall, may tip the balance between source and sink. Recent trends have seen a greater flux of dissolved organic matter (DOM) from peatlands to surface waters and a change in DOM character, presenting challenges to water treatment, for example in terms of increased production of disinfectant by-products (DBPs). Peat systems border a large proportion of reservoirs in the UK so uncertainty regarding DOM quantity and quality is a concern for water utilities. This study considered five peatland vegetation types (Sphagnum spp., Calluna vulgaris, Molinea caerulea, peat soil and mixed litter) collected from the Exmoor National Park, UK where it is hypothesised that peat formation may be strongly affected by future changes to climate. A factorial experiment design to simulate climate was used, considering vegetation type, temperature and rainfall amount using a current baseline and predictions from the UKCP09 model. Gaseous fluxes of carbon were monitored over a two month period to quantify the effect on carbon mineralisation rates while 13C NMR analysis was employed to track which classes of compounds decayed preferentially. The DOM collected was characterised using UV and fluorescence techniques before being subject to standard drinking water treatment processes (coagulation/flocculation followed by chlorination). The effect of the experimental factors on DOM amenability to removal and propensity to form DBPs was then considered, with both trihalomethane (THM) and haloacetonitrile (HAN) DBP classes monitored. Initial results have shown a

  9. The Measurement of Dissolved Oxygen

    ERIC Educational Resources Information Center

    Thistlethwayte, D.; And Others

    1974-01-01

    Describes an experiment in environmental chemistry which serves to determine the dissolved oxygen concentration in both fresh and saline water. Applications of the method at the undergraduate and secondary school levels are recommended. (CC)

  10. METHOD OF DISSOLVING URANIUM METAL

    DOEpatents

    Slotin, L.A.

    1958-02-18

    This patent relates to an economicai means of dissolving metallic uranium. It has been found that the addition of a small amount of perchloric acid to the concentrated nitric acid in which the uranium is being dissolved greatly shortens the time necessary for dissolution of the metal. Thus the use of about 1 or 2 percent of perchioric acid based on the weight of the nitric acid used, reduces the time of dissolution of uranium by a factor of about 100.

  11. Effect of Greenhouse Gases Dissolved in Seawater.

    PubMed

    Matsunaga, Shigeki

    2016-01-01

    A molecular dynamics simulation has been performed on the greenhouse gases carbon dioxide and methane dissolved in a sodium chloride aqueous solution, as a simple model of seawater. A carbon dioxide molecule is also treated as a hydrogen carbonate ion. The structure, coordination number, diffusion coefficient, shear viscosity, specific heat, and thermal conductivity of the solutions have been discussed. The anomalous behaviors of these properties, especially the negative pressure dependence of thermal conductivity, have been observed in the higher-pressure region. PMID:26729101

  12. Effect of Greenhouse Gases Dissolved in Seawater

    PubMed Central

    Matsunaga, Shigeki

    2015-01-01

    A molecular dynamics simulation has been performed on the greenhouse gases carbon dioxide and methane dissolved in a sodium chloride aqueous solution, as a simple model of seawater. A carbon dioxide molecule is also treated as a hydrogen carbonate ion. The structure, coordination number, diffusion coefficient, shear viscosity, specific heat, and thermal conductivity of the solutions have been discussed. The anomalous behaviors of these properties, especially the negative pressure dependence of thermal conductivity, have been observed in the higher-pressure region. PMID:26729101

  13. Online dissolved methane and total dissolved sulfide measurement in sewers.

    PubMed

    Liu, Yiwen; Sharma, Keshab R; Fluggen, Markus; O'Halloran, Kelly; Murthy, Sudhir; Yuan, Zhiguo

    2015-01-01

    Recent studies using short-term manual sampling of sewage followed by off-line laboratory gas chromatography (GC) measurement have shown that a substantial amount of dissolved methane is produced in sewer systems. However, only limited data has been acquired to date due to the low frequency and short span of this method, which cannot capture the dynamic variations of in-sewer dissolved methane concentrations. In this study, a newly developed online measuring device was used to monitor dissolved methane concentrations at the end of a rising main sewer network, over two periods of three weeks each, in summer and early winter, respectively. This device uses an online gas-phase methane sensor to measure methane under equilibrium conditions after being stripped from the sewage. The data are then converted to liquid-phase methane concentrations according to Henry's Law. The detection limit and range are suitable for sewer application and can be adjusted by varying the ratio of liquid-to-gas phase volume settings. The measurement presented good linearity (R² > 0.95) during field application, when compared to off-line measurements. The overall data set showed a wide variation in dissolved methane concentration of 5-15 mg/L in summer and 3.5-12 mg/L in winter, resulting in a significant average daily production of 24.6 and 19.0 kg-CH₄/d, respectively, from the network with a daily average sewage flow of 2840 m³/day. The dissolved methane concentration demonstrated a clear diurnal pattern coinciding with flow and sulfide fluctuation, implying a relationship with the wastewater hydraulic retention time (HRT). The total dissolved sulfide (TDS) concentration in sewers can be determined simultaneously with the same principle. PMID:25462721

  14. Reducing emissions from uranium dissolving

    SciTech Connect

    Griffith, W.L.; Compere, A.L.; Huxtable, W.P.; Googin, J.M.

    1992-10-01

    This study was designed to assess the feasibility of decreasing NO{sub x} emissions from the current uranium alloy scrap tray dissolving facility. In the current process, uranium scrap is dissolved in boiling nitric acid in shallow stainless-steel trays. As scrap dissolves, more metal and more nitric acid are added to the tray by operating personnel. Safe geometry is assured by keeping liquid level at or below 5 cm, the depth of a safe infinite slab. The accountability batch control system provides additional protection against criticality. Both uranium and uranium alloys are dissolved. Nitric acid is recovered from the vapors for reuse. Metal nitrates are sent to uranium recovery. Brown NO{sub x} fumes evolved during dissolving have occasionally resulted in a visible plume from the trays. The fuming is most noticeable during startup and after addition of fresh acid to a tray. Present environmental regulations are expected to require control of brown NO{sub x} emissions. A detailed review of the literature, indicated the feasibility of slightly altering process chemistry to favor the production of NO{sub 2} which can be scrubbed and recycled as nitric acid. Methods for controlling the process to manage offgas product distribution and to minimize chemical reaction hazards were also considered.

  15. Reducing emissions from uranium dissolving

    SciTech Connect

    Griffith, W.L.; Compere, A.L.; Huxtable, W.P.; Googin, J.M.

    1992-10-01

    This study was designed to assess the feasibility of decreasing NO[sub x] emissions from the current uranium alloy scrap tray dissolving facility. In the current process, uranium scrap is dissolved in boiling nitric acid in shallow stainless-steel trays. As scrap dissolves, more metal and more nitric acid are added to the tray by operating personnel. Safe geometry is assured by keeping liquid level at or below 5 cm, the depth of a safe infinite slab. The accountability batch control system provides additional protection against criticality. Both uranium and uranium alloys are dissolved. Nitric acid is recovered from the vapors for reuse. Metal nitrates are sent to uranium recovery. Brown NO[sub x] fumes evolved during dissolving have occasionally resulted in a visible plume from the trays. The fuming is most noticeable during startup and after addition of fresh acid to a tray. Present environmental regulations are expected to require control of brown NO[sub x] emissions. A detailed review of the literature, indicated the feasibility of slightly altering process chemistry to favor the production of NO[sub 2] which can be scrubbed and recycled as nitric acid. Methods for controlling the process to manage offgas product distribution and to minimize chemical reaction hazards were also considered.

  16. Dissolving Polymers in Ionic Liquids.

    NASA Astrophysics Data System (ADS)

    Hoagland, David; Harner, John

    2009-03-01

    Dissolution and phase behavior of polymers in ionic liquids have been assessed by solution characterization techniques such as intrinsic viscosity and light scattering (static and dynamic). Elevated viscosity proved the greatest obstacle. As yet, whether principles standard to conventional polymer solutions apply to ionic liquid solutions is uncertain, especially for polymers such as polyelectrolytes and hydrophilic block copolymers that may specifically interact with ionic liquid anions or cations. For flexible polyelectrolytes (polymers releasing counterions into high dielectric solvents), characterization in ionic liquids suggests behaviors more typical of neutral polymer. Coil sizes and conformations are approximately the same as in aqueous buffer. Further, several globular proteins dissolve in a hydrophilic ionic liquid with conformations analogous to those in buffer. General principles of solubility, however, remain unclear, making predictions of which polymer dissolves in which ionic liquid difficult; several otherwise intractable polymers (e.g., cellulose, polyvinyl alcohol) dissolve and can be efficiently functionalized in ionic liquids.

  17. Reducing Emissions from Uranium Dissolving

    SciTech Connect

    Griffith, W.L.

    1992-01-01

    This study was designed to assess the feasibility of decreasing NO{sub x} emissions from the current uranium alloy scrap tray dissolving facility. In the current process, uranium scrap is dissolved in boiling nitric acid in shallow stainless-steel trays. As scrap dissolves, more metal and more nitric acid are added to the tray by operating personnel. Safe geometry is assured by keeping liquid level at or below 5 cm, the depth of a safe infinite slab. The accountability batch control system provides additional protection against criticality. The trays are steam coil heated. The process has operated satisfactorily, with few difficulties, for decades. Both uranium and uranium alloys are dissolved. Nitric acid is recovered from the vapors for reuse. Metal nitrates are sent to uranium recovery. Brown NO{sub x} fumes evolved during dissolving have occasionally resulted in a visible plume from the trays. The fuming is most noticeable during startup and after addition of fresh acid to a tray. Present environmental regulations are expected to require control of brown NO{sub x} emissions. Because NO{sub x} is hazardous, fumes should be suppressed whenever the electric blower system is inoperable. Because the tray dissolving process has worked well for decades, as much of the current capital equipment and operating procedures as possible were preserved. A detailed review of the literature, indicated the feasibility of slightly altering process chemistry to favor the production of NO{sub 2}, which can be scrubbed and recycled as nitric acid. Methods for controlling the process to manage offgas product distribution and to minimize chemical reaction hazards were also considered.

  18. Air classification: Potential treatment method for optimized recycling or utilization of fine-grained air pollution control residues obtained from dry off-gas cleaning high-temperature processing systems.

    PubMed

    Lanzerstorfer, Christof

    2015-11-01

    In the dust collected from the off-gas of high-temperature processes, usually components that are volatile at the process temperature are enriched. In the recycling of the dust, the concentration of these volatile components is frequently limited to avoid operation problems. Also, for external utilization the concentration of such volatile components, especially heavy metals, is often restricted. The concentration of the volatile components is usually higher in the fine fractions of the collected dust. Therefore, air classification is a potential treatment method to deplete the coarse material from these volatile components by splitting off a fines fraction with an increased concentration of those volatile components. In this work, the procedure of a sequential classification using a laboratory air classifier and the calculations required for the evaluation of air classification for a certain application were demonstrated by taking the example of a fly ash sample from a biomass combustion plant. In the investigated example, the Pb content in the coarse fraction could be reduced to 60% by separation of 20% fines. For the non-volatile Mg the content was almost constant. It can be concluded that air classification is an appropriate method for the treatment of off-gas cleaning residues. PMID:26268600

  19. METHOD OF DISSOLVING METALLIC URANIUM

    DOEpatents

    Schulz, W.W.

    1959-07-28

    A process is presented for more rapidly dissolving metallic uranium which comprises contacting the uranium with a mixture of nitric and phosphoric acids. The preferred concentration is a mixture which is about 10 M in nitric acid and between 0.1 to 0.15 M in phosphoric acid.

  20. Dissolving pulp from jute stick.

    PubMed

    Matin, Mhafuza; Rahaman, M Mostafizur; Nayeem, Jannatun; Sarkar, Mamon; Jahan, M Sarwar

    2015-01-22

    Jute stick is woody portion of jute plant, which remain as leftover after extracting bast fibre. Presently, it is being used for fencing in the rural area. In this investigation, biorefinery concept was initiated in producing dissolving pulp from jute stick by pre-hydrolysis kraft process. At 170°C for 1h of pre-hydrolysis, 70% of hemicelluloses was dissolved with negligible loss of α-cellulose. At this condition, 75% of dissolved sugars in the pre-hydrolysis liquor were in the oligomeric form. The pre-hydrolysed jute stick was subsequently pulped by kraft process with the variation of active alkali. The pulp yield was 36.2% with kappa number 18.5 at the conditions of 16% active alkali for 2h of cooking at 170°C. Final pulp was produced with 92% α-cellulose and 89% brightness after D0EpD1EpD1 bleaching. The produced dissolving pulp can be used in rayon production. PMID:25439866

  1. Erosion patterns on dissolving blocks

    NASA Astrophysics Data System (ADS)

    Courrech du Pont, Sylvain; Cohen, Caroline; Derr, Julien; Berhanu, Michael

    2016-04-01

    Patterns in nature are shaped under water flows and wind action, and the understanding of their morphodynamics goes through the identification of the physical mechanisms at play. When a dissoluble body is exposed to a water flow, typical patterns with scallop-like shapes may appear [1,2]. These shapes are observed on the walls of underground rivers or icebergs. We experimentally study the erosion of dissolving bodies made of salt, caramel or ice into water solutions without external flow. The dissolving mixture, which is created at the solid/liquid interface, undergoes a buoyancy-driven instability comparable to a Rayleigh-Bénard instability so that the dissolving front destabilizes into filaments. This mechanism yields to spatial variations of solute concentration and to differential dissolution of the dissolving block. We first observe longitudinal stripes with a well defined wavelength, which evolve towards chevrons and scallops that interact and move again the dissolving current. Thanks to a careful analysis of the competing physical mechanisms, we propose scaling laws, which account for the characteristic lengths and times of the early regime in experiments. The long-term evolution of patterns is understood qualitatively. A close related mechanism has been proposed to explain structures observed on the basal boundary of ice cover on brakish lakes [3] and we suggest that our experiments are analogous and explain the scallop-like patterns on iceberg walls. [1] P. Meakin and B. Jamtveit, Geological pattern formation by growth and dissolution in aqueous systems, Proc. R. Soc. A 466, 659-694 (2010). [2] P.N. Blumberg and R.L. Curl, Experimental and theoretical studies of dissolution roughness, J. Fluid Mech. 65, 735-751 (1974). [3] L. Solari and G. Parker, Morphodynamic modelling of the basal boundary of ice cover on brakish lakes, J.G.R. 118, 1432-1442 (2013).

  2. A photochemically resistant component in riverine dissolved black carbon

    NASA Astrophysics Data System (ADS)

    Dittmar, Thorsten; Riedel, Thomas; Niggemann, Jutta; Vähätalo, Anssi

    2015-04-01

    Rivers transport combustion-derived dissolved black carbon (DBC) to the oceans at an annual flux that is much higher than required to balance the oceanic inventory of DBC. To resolve this mismatch we studied the long-term stability of DBC in ten major world rivers that together account for approximately 1/3 of the global freshwater discharge to the oceans. Riverine DBC was remarkably resistant against microbial degradation, but decomposition of nearly all chromophoric dissolved organic matter under extensive irradiation with simulated sunlight removed almost 80% of DBC. Photochemically transformed DBC was further microbially decomposed by more than 10% in a subsequent one-year long bioassay. Based on these findings, on a global scale, the estimated riverine flux of microbially degraded and photo-resistant DBC is sufficient to replenish the oceans with DBC and likely contributes to the dissolved organic matter pool that persists in the oceans and sequesters carbon for centuries to millennia.

  3. Comparison of dissolved and total metals concentrations from acute tests with saltwater organisms

    SciTech Connect

    Lussier, S.M.; Boothman, W.S.; Champlin, D.; Poucher, S.; Helmstetten, A.

    1999-05-01

    Aquatic life criteria (ALC) have traditionally been expressed for meals in terms of total-recoverable or acid-soluble concentrations. Recent US Environmental protection Agency policy recommended use of dissolved metal concentrations for setting water quality standards. Criteria derived from previous tests could be expressed in terms of dissolved metals if ratios of dissolved-to-total concentrations in those tests were consistent. Using those metals with insufficient dissolved metals data to directly derive criteria (arsenic (III), cadmium, chromium (VI), lead, nickel, selenium (IV), and zinc), the authors measured both total and dissolved metal concentrations in acute saltwater static and flow-through tests. Exposure conditions simulated those of original tests used to derive ALC. Partitioning of metals between dissolved and particulate forms was very consistent. Dissolved metal concentrations were greater than 90% of total concentrations in all tests, exceeding 95% in 10 of 13 tests. Dissolved-to-total metal ratios did not vary significantly with concentration, time, or type of test. Biological responses were consistent with historical data. Results implied that in acute saltwater toxicity tests used to establish ALC, metals were primarily dissolved. Thus criteria developed for metals based on total concentrations should be equally valid when expressed in terms of dissolved concentrations.

  4. PROCESS OF DISSOLVING ZIRCONIUM ALLOYS

    DOEpatents

    Shor, R.S.; Vogler, S.

    1958-01-21

    A process is described for dissolving binary zirconium-uranium alloys where the uranium content is about 2%. In prior dissolution procedures for these alloys, an oxidizing agent was added to prevent the precipitation of uranium tetrafluoride. In the present method complete dissolution is accomplished without the use of the oxidizing agent by using only the stoichiometric amount or slight excess of HF required by the zirconium. The concentration of the acid may range from 2M to 10M and the dissolution is advatageously carried out at a temperature of 80 deg C.

  5. Novel method for online monitoring of dissolved N2O concentrations through a gas stripping device.

    PubMed

    Mampaey, Kris E; van Dongen, Udo G J M; van Loosdrecht, Mark C M; Volcke, Eveline I P

    2015-01-01

    Nitrous oxide emissions from wastewater treatment plants are currently measured by online gas phase analysis or grab sampling from the liquid phase. In this study, a novel method is presented to monitor the liquid phase N2O concentration for aerated as well as non-aerated conditions/reactors, following variations both in time and in space. The monitoring method consists of a gas stripping device, of which the measurement principle is based on a continuous flow of reactor liquid through a stripping flask and subsequent analysis of the N2O concentration in the stripped gas phase. The method was theoretically and experimentally evaluated for its fit for use in the wastewater treatment context. Besides, the influence of design and operating variables on the performance of the gas stripping device was addressed. This method can easily be integrated with online off-gas measurements and allows to better investigate the origin of the gas emissions from the treatment plant. Liquid phase measurements of N2O are of use in mitigation of these emissions. The method can also be applied to measure other dissolved gasses, such as methane, being another important greenhouse gas. PMID:25573615

  6. Erosion Patterns on Dissolving Surfaces

    NASA Astrophysics Data System (ADS)

    Cohen, Caroline; Polizzi, Stefano; Berhanu, Michael; Derr, Julien; Courrech Du Pont, Sylvain

    2015-11-01

    The shaping of landscapes results from water or wind erosional processes. Here we focus on dissolution processes. We perform laboratory experiments on hard caramel bodies, which dissolve on a short timescale, compared to geological material such as limestone. We highlight the spontaneous appearance of a dissolution pattern with no external flow. When a tilted hard caramel block dissolves, the syrup (denser than water) sinks in the bath and induces a flow, which results in a pattern on the bottom of the block. First parallel stripes appear, which evolve to transversal scallops in about one hour. The whole pattern moves upstream at a slow velocity. The stripes appearance is due to a buoyancy-driven instability. By varying the density and the viscosity of the bath, we show that the initial wavelengths of the pattern are in agreement with those given by the solutal Rayleigh-Benard number. Later pattern evolution to scallops results from complex interactions between the flow and the topography. Finally we emphasize that similar mechanism of patterns formation can occur in the dissolution of minerals like salt, but also in the shaping of the bottom face of melting icebergs in the cold seas.

  7. METHOD OF DISSOLVING REFRACTORY ALLOYS

    DOEpatents

    Helton, D.M.; Savolainen, J.K.

    1963-04-23

    This patent relates to the dissolution of alloys of uranium with zirconium, thorium, molybdenum, or niobium. The alloy is contacted with an anhydrous solution of mercuric chloride in a low-molecular-weight monohydric alcohol to produce a mercury-containing alcohol slurry. The slurry is then converted to an aqueous system by adding water and driving off the alcohol. The resulting aqueous slurry is electrolyzed in the presence of a mercury cathode to remove the mercury and produce a uranium-bearing aqueous solution. This process is useful for dissolving irradiated nuclear reactor fuels for radiochemical reprocessing by solvent extraction. In addition, zirconium-alloy cladding is selectively removed from uranium dioxide fuel compacts by this means. (AEC)

  8. Progress in dissolving modified LEU Cintichem targets

    SciTech Connect

    Leonard, R.A.; Chen, L.; Mertz, C.J.; Vandegrift, G.F.

    1996-12-31

    A process is under development to use low-enriched uranium (LEU) metal targets for production of {sup 99}Mo. The first step is to dissolve the irradiated foil. In past work, this has been done by heating a closed (sealed) vessel containing the foil and a solution of nitric and sulfuric acids. In this work, the authors have demonstrated that (1) the dissolver solution can contain nitric acid alone, (2) uranium dioxide is also dissolved by nitric acid alone, and (3) barrier metals of Cu, Fe, or Ni on the U foil are also dissolved by nitric acid. Changes to the dissolver design and operation needed to accommodate the uranium foil are discussed, including (1) simple operations that are easy to do in a remote-maintenance facility, (2) heat removal from the irradiated LEU foil, and (3) cold trap operation with high dissolver pressures.

  9. Dissolved air-flotation processes. Technical report

    SciTech Connect

    Krofta, M.; Wang, L.K.

    1986-11-05

    The theories and applications of various dissolved-air-flotation clarifiers (Supracell, Sandfloat, Floatpress, and Sedifloat) are presented. Supracell is a high-rate dissolved-air-flotation clarifier with only 3 to 5 minutes of detention time. Major application of Supracell is industrial-effluent treatment. Sandfloat is a package plant consisting of flocculation, dissolved-air floatation and automatic backwash filtration, and designed for either potable water treatment or tertiary wastewater-treatment. Sedifloat is a wastewater-treatment package plant consisting of both sedimentation and dissolved-air flotation. Floatpress consists of both dissolved air flotation and filter press and is specifically designed for sludge thickening. A Krofta Bargefloat is a floating lake-water clarification plant designed for acid-rain neutralization, phosphorus removal, algae removal and lake-water purification. Bargefloat has built-in chemical feeders, flocculator, dissolved-air-flotation clarifier and sand filter on a barge.

  10. Design/installation and structural integrity assessment of Bethel Valley low-level waste collection and transfer system upgrade for Building 3092 (Central Off-Gas Scrubber Facility) at Oak Ridge National Laboratory

    SciTech Connect

    1995-01-01

    This document describes and assesses planned modifications to be made to the Building 3092 Central Off-Gas Scrubber Facility of the Oak Ridge National Laboratory, Oak Ridge, Tennessee. The modifications are made in responsible to the requirements of 40CFR264 Subpart J, relating to environmental protection requirements for buried tank systems. The modifications include the provision of a new scrubber recirculation tank in a new, below ground, lines concrete vault, replacing and existing recirculation sump that does not provide double containment. A new buried, double contained pipeline is provided to permit discharge of spent scrubber recirculation fluid to the Central Waste Collection Header. The new vault, tank, and discharge line are provided with leak detection and provisions to remove accumulated liquid. New scrubber recirculation pumps, piping, and accessories are also provided. This assessment concludes that the planned modifications comply with applicable requirements of 40CFR264 Subpart J, as set forth in Appendix F to the Federal Facility Agreement, Docket No. 89-04-FF, covering the Oak Ridge Reservation.

  11. [Concentrations and Speciation of Dissolved Heavy Metal in Rainwater in Guiyang, China].

    PubMed

    Zhu, Zhao-zhou; Li, Jun; Wang, Zhi-ru

    2015-06-01

    In order to understand the pollution situation, as well as seasonal changes in characteristics and speciation of dissolved heavy metals in acid rain control zone, the concentrations of dissolved heavy metals in rainwater collected at Guiyang were measured using inductively coupled plasma mass spectrometry (ICP-MS). And the speciation of dissolved heavy metals was further simulated by PHREEQC model. The results showed that the dissolved Co, Ni, Cu, Zn and Cd concentrations were low and not higher than the national standards for drinking water quality in China. The dissolved Pd concentrations were high in fall and winter and higher than the national standards for drinking water quality in China. The Co and Ni in rainwater mainly came from the crust and there was almost no human impact. The Cu, Zn, Cd and Pd pollutions in rainwater were affected by human activity with different levels. The degrees of contamination in autumn and winter were more serious than those in spring and summer. The free metal ion species was the dominant form of dissolved heavy metal, accounting for 47.27%-95.28% of the dissolved metal in rainwater from Guiyang city. The free metal ion species was followed in abundance by Metal-Oxalate and Metal-sulfate complexes that accounted for 0.72% -51.87% and 0.50%-7.66%, respectively. The acidity of rainwater, acid type as well as content of ligand more likely controlled the distribution of dissolved heavy metal in precipitation. PMID:26387294

  12. Investigating Students' Understanding of the Dissolving Process

    ERIC Educational Resources Information Center

    Naah, Basil M.; Sanger, Michael J.

    2013-01-01

    In a previous study, the authors identified several student misconceptions regarding the process of dissolving ionic compounds in water. The present study used multiple-choice questions whose distractors were derived from these misconceptions to assess students' understanding of the dissolving process at the symbolic and particulate levels. The…

  13. Dissolved Oxygen Data for Coos Estuary (Oregon)

    EPA Science Inventory

    The purpose of this product is the transmittal of dissolved oxygen data collected in the Coos Estuary, Oregon to Ms. Molly O'Neill (University of Oregon), for use in her studies on the factors influencing spatial and temporal patterns in dissolved oxygen in this estuary. These d...

  14. Influence of dissolved organic materials on turbid water optical properties and remote-sensing reflectance

    NASA Technical Reports Server (NTRS)

    Witte, W. G.; Whitlock, C. H.; Harriss, R. C.; Usry, J. W.; Poole, L. R.; Houghton, W. M.; Morris, W. D.; Gurganus, E. A.

    1982-01-01

    The effects of dissolved organic materials on turbid-water optical properties are assessed, by means of field measurements and laboratory simulations in which upwelled reflectance, attenuation, absorption, and backscatter spectral properties at wavelengths from 450 to 800 nm are examined in relation to water chemistry. The data show that dissolved organic materials decrease upwelled reflectance from turbid waters, and that the decrease in reflectance is a nonlinear function of concentration with the largest gradients at low carbon concentrations, depending on wavelength. Upwelled reflectance is found to be highly correlated with two backscatter-absorption parameters used in some optical models, which are nonlinear with dissolved organic material concentration change.

  15. Fish Passage Through a Simulated Horizontal Bulb Turbine Pressure Regime: A Supplement to"Laboratory Studies of the Effects of Pressure and Dissolved Gas Supersaturation on Turbine-Passed Fish"

    SciTech Connect

    Abernethy, Cary S. ); Amidan, Brett G. ); Cada, G F.

    2003-07-31

    Migratory and resident fish in the Columbia River Basin are exposed to stresses associated with hydroelectric power production, including pressure changes during turbine passage. The responses of fall chinook salmon and bluegill sunfish to rapid pressure change was investigated at the Pacific Northwest National Laboratory. Previous test series evaluated the effects of passage through a vertical Kaplan turbine under the"worst case" pressure conditions and under less severe conditions where pressure changes were minimized. For this series of tests, pressure changes were modified to simulate passage through a horizontal bulb turbine, commonly installed at low head dams. The results were compared to results from previous test series. Migratory and resident fish in the Columbia River Basin are exposed to stresses associated with hydroelectric power production, including pressure changes during turbine passage. The responses of fall chinook salmon and bluegill sunfish to rapid pressure change was investigated at the Pacific Northwest National Laboratory. Previous test series evaluated the effects of passage through a vertical Kaplan turbine under the"worst case" pressure conditions and under less severe conditions where pressure changes were minimized. For this series of tests, pressure changes were modified to simulate passage through a horizontal bulb turbine, commonly installed at low head dams. The results were compared to results from previous test series. Both fish species were acclimated for 16-22 hours at either surface (101 kPa; 1 atm) or 30 ft (191 kPa; 1.9 atm) of pressure in a hyperbaric chamber before exposure to a pressure scenario simulating passage through a horizontal bulb turbine. The simulation was as follows: gradual pressure increase to about 2 atm of pressure, followed by a sudden (0.4 second) decrease in pressure to either 0.7 or 0.95 atm, followed by gradual return to 1 atm (surface water pressure). Following the exposure, fish were held at

  16. AN EMPIRICAL MODEL FOR DISSOLVED PHOSPHORUS IN RUNOFF FROM SURFACE-APPLIED FERTILIZERS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dissolved phosphorus (P) in runoff from surface-applied fertilizers can be relatively great, but commonly used field or watershed-scale computer models often do not simulate direct transfer of fertilizer P to runoff. Using data from our own simulated rainfall experiments and published runoff studies...

  17. Documentation of a dissolved-solids model of the Tongue River, southeastern Montana

    USGS Publications Warehouse

    Woods, Paul F.

    1981-01-01

    A model has been developed for assessing potential increases in dissolved solids of the Tongue River as a result of leaching of overburden materials used to backfill pits in surface coal-mining operations. The model allows spatial and temporal simulation of streamflow and dissolved-solids loads and concentrations under user-defined scenarios of surface coal mining and agricultural development. The model routes an input quantity of streamflow and dissolved solids from the upstream end to the downstream end of a stream reach while algebraically accounting for gains and losses of streamflow and dissolved solids within the stream reach. Input data needed to operate the model include the following: simulation number, designation of hydrologic conditions for each simulated month, either user-defined or regression-defined concentrations of dissolved solids input by the Tongue River Reservoir, number of irrigated acres, number of mined acres, dissolved-solids concentration of mine leachates and quantity of other water losses. A listing of the Fortran computer program, definitions of all variables in the model, and an example output permit use of the model by interested persons. (USGS)

  18. Transient Dissolved Organic Carbon Through Soils

    NASA Astrophysics Data System (ADS)

    Mei, Y.; Hornberger, G. M.; Kaplan, L. A.; Newbold, J. D.; Aufdenkampe, A. K.; Tsang, Y.

    2009-12-01

    Dissolved organic carbon (DOC) is an important constituent of soil solution that plays a role in many chemical and biological processes in soils; it is also an important energy source for bacteria in the soil ecosystem. Hydrology has a significant control on the transport and fate of dissolved organic carbon in the soil but mechanisms that affect said transport are not well understood. In particular, dynamic information on DOC transport through forest soils on short time scales (one or two precipitation event) is lacking at present. DOC is a very complex mix of organic compounds. A key to quantifying DOC dynamics is to establish useful approximations for behavior of this complex mixture. Biodegradable dissolved organic carbon (BDOC) is an important part of DOC. It is reported that between 12 and 44% of DOC released from the forest floor can be decomposed in solutions by indigenous microbes. In our study, we considered how DOC, BDOC, and flow interact in soil columns. In-situ soil cores with two different lengths were installed under a mixed deciduous canopy. The effects of artificial rain on DOC and BDOC transport were examined by dripping nano pure water amended with bromide on the top of soil cores and sampling the water collected at the bottom of the cores for DOC and BDOC. We used plug-flow biofilm reactors to measure the BDOC concentration. It is likely that reduced rates of decomposition in dry soils will cause microbial products of DOC to accumulate; hence DOC concentration should be high at the first flush of rain and decline as the event proceeds. The experimental results show the expected pattern, that is, the first samples we collected always had the highest DOC and BDOC concentrations. The concentrations tend to decline through the simulated precipitation event. Application of a second “storm” forty minutes after the cessation of the first application of water resulted in effluent DOC concentration increasing a small amount initially and then

  19. Fish passage through a simulated horizontal bulb turbine pressure regime: A supplement to "Laboratory Studies of the Effects of Pressure and Dissolved Gas Supersaturation on Turbine-Passed Fish"

    SciTech Connect

    Abernethy, C. S.; Amidan, B. G.; Cada, G. F.

    2003-07-01

    Migratory and resident fish in the Columbia River Basin are exposed to stresses associated with hydroelectric power production, including pressure changes during turbine passage. The responses of fall chinook salmon and bluegill sunfish to rapid pressure change was investigated at the Pacific Northwest National Laboratory. Previous test series evaluated the effects of passage through a vertical Kaplan turbine under the “worst case” pressure conditions (Abernethy et al. 2001) and under less severe conditions where pressure changes were minimized (Abernethy et al. 2002). For this series of tests, pressure changes were modified to simulate passage through a horizontal bulb turbine, commonly installed at low-head dams. The results were compared to results from previous test series. Tests indicated that for most of the cross-sectional area of a horizontal bulb turbine, pressure changes occurring during turbine passage are not harmful to fall chinook salmon and only minimally harmful to bluegill. However, some areas within a horizontal bulb turbine may have extreme pressure conditions that would be harmful to fish. These scenarios were not tested because they represent a small cross-sectional area of the turbine compared to the centerline pressures scenarios used in these tests.

  20. The Influence of Physical Forcing on Bottom-water Dissolved Oxygen within the Caloosahatchee River Estuary, FL

    EPA Science Inventory

    Environmental Fluid Dynamic Code (EFDC), a numerical estuarine and coastal ocean circulation hydrodynamic model, was used to simulate the distribution of dissolved oxygen (DO), salinity, temperature, nutrients (nitrogen and phosphorus), and chlorophyll a in the Caloosahatchee Riv...

  1. FDA Approves First Fully Dissolvable Stent

    MedlinePlus

    ... fullstory_159721.html FDA Approves First Fully Dissolvable Stent Device is absorbed by the body after about ... July 5, 2016 (HealthDay News) -- The first coronary stent to be gradually absorbed by the body has ...

  2. Photochemistry of Dissolved Black Carbon Released from Biochar: Reactive Oxygen Species Generation and Phototransformation.

    PubMed

    Fu, Heyun; Liu, Huiting; Mao, Jingdong; Chu, Wenying; Li, Qilin; Alvarez, Pedro J J; Qu, Xiaolei; Zhu, Dongqiang

    2016-02-01

    Dissolved black carbon (BC) released from biochar can be one of the more photoactive components in the dissolved organic matter (DOM) pool. Dissolved BC was mainly composed of aliphatics and aromatics substituted by aromatic C-O and carboxyl/ester/quinone moieties as determined by solid-state nuclear magnetic resonance. It underwent 56% loss of absorbance at 254 nm, almost complete loss of fluorescence, and 30% mineralization during a 169 h simulated sunlight exposure. Photoreactions preferentially targeted aromatic and methyl moieties, generating CH2/CH/C and carboxyl/ester/quinone functional groups. During irradiation, dissolved BC generated reactive oxygen species (ROS) including singlet oxygen and superoxide. The apparent quantum yield of singlet oxygen was 4.07 ± 0.19%, 2-3 fold higher than many well-studied DOM. Carbonyl-containing structures other than aromatic ketones were involved in the singlet oxygen sensitization. The generation of superoxide apparently depended on electron transfer reactions mediated by silica minerals in dissolved BC, in which phenolic structures served as electron donors. Self-generated ROS played an important role in the phototransformation. Photobleaching of dissolved BC decreased its ability to further generate ROS due to lower light absorption. These findings have significant implications on the environmental fate of dissolved BC and that of priority pollutants. PMID:26717492

  3. Photochemical flocculation of terrestrial dissolved organic matter and iron

    NASA Astrophysics Data System (ADS)

    Helms, John R.; Mao, Jingdong; Schmidt-Rohr, Klaus; Abdulla, Hussain; Mopper, Kenneth

    2013-11-01

    Dissolved organic matter (DOM) rich water samples (Great Dismal Swamp, Virginia) were 0.1-μm filtered and UV-irradiated in a solar simulator for 30 days. During the irradiation, pH increased, particulate organic matter (POM) and particulate iron formed. After 30 days, 7% of the dissolved organic carbon (DOC) was converted to POC while 75% was remineralized. Approximately 87% of the iron was removed from the dissolved phase after 30 days, but iron did not flocculate until a major fraction of DOM was removed by photochemical degradation and flocculation (>10 days); thus, during the initial 10 days, there were sufficient organic ligands present or the pH was low enough to keep iron in solution. Nuclear magnetic resonance and Fourier transform infrared spectroscopies indicated that photochemically flocculated POM was more aliphatic than the residual non-flocculated DOM. Photochemically flocculated POM was also enriched in amide functionality, while carbohydrate-like material was resistant to both photochemical degradation and flocculation. Abiotic photochemical flocculation likely removes a significant fraction of terrestrial DOM from the upper water column between headwaters and the ocean, but has previously been ignored. Preliminary evidence suggests that this process may significantly impact the transport of DOM and POM in ocean margin environments including estuaries.

  4. Photo-lability of deep ocean dissolved black carbon

    NASA Astrophysics Data System (ADS)

    Stubbins, A.; Niggemann, J.; Dittmar, T.

    2012-01-01

    Dissolved black carbon (DBC), defined here as condensed aromatics isolated from seawater via PPL solid phase extraction and quantified as benzene polycarboxylic acid oxidation products, is a significant component of the oceanic dissolved organic carbon (DOC) pool. These condensed aromatics are widely distributed in the open ocean and appear to be tens of thousands of years old. As such DBC is regarded as highly refractory. In the current study, the photo-lability of DBC, DOC and coloured dissolved organic matter (CDOM; ultraviolet-visible absorbance) were determined over the course of a 28 d irradiation of North Atlantic Deep Water under a solar simulator. During the irradiation DBC fell from 1044 ± 164 nM C to 55 ± 15 nM C, a 20-fold decrease in concentration. Dissolved black carbon photo-degradation was more rapid and more extensive than for bulk CDOM and DOC. Further, the photo-lability of components of the DBC pool increased with their degree of aromatic condensation. These trends indicate that a continuum of compounds of varying photo-lability exists within the marine DOC pool. In this continuum, photo-lability scales with aromatic character, specifically the degree of condensation. Scaling the rapid photo-degradation of DBC to rates of DOC photo-mineralisation for the global ocean leads to an estimated photo-chemical half-life for oceanic DBC of less than 800 yr. This is more than an order of magnitude shorter than the apparent age of DBC in the ocean. Photo-degradation is therefore posited as the primary sink for oceanic DBC and the survival of DBC molecules in the oceans for millennia appears to be facilitated not by their inherent inertness but by the rate at which they are cycled through the surface ocean's photic zone.

  5. Dialysate With High Dissolved Hydrogen Facilitates Dissociation of Indoxyl Sulfate From Albumin

    PubMed Central

    Tange, Yoshihiro; Takesawa, Shingo; Yoshitake, Shigenori

    2015-01-01

    Background: Protein-bound toxins such as indoxyl sulfate (IS) are not efficiently removed by conventional hemodialysis (HD). Objectives: To improve the removal of IS, we performed an in vitro study to evaluate the effects of high dissolved hydrogen on the dissociation of IS from albumin using simulated HD. Materials and Methods: Wasted dialysate from peritoneal dialysis was concentrated a hundred times using extracorporeal ultrafiltration method. Dialysate with high dissolved hydrogen was made by mixing concentrated dialysis solution and electrolyzed-reduced water. The amounts of free fractions of IS were determined by high performance liquid chromatography. Results: IS was significantly dissociated from albumin using dialysate with high dissolved hydrogen compared with conventional dialysate (P < 0.05). Conclusions: Effective removal of IS is expected using a dialysate with high dissolved hydrogen. PMID:25883914

  6. Dissolved-Solids Load in Henrys Fork Upstream from the Confluence with Antelope Wash, Wyoming, Water Years 1970-2009

    USGS Publications Warehouse

    Foster, Katharine; Kenney, Terry A.

    2010-01-01

    Annual dissolved-solids load at the mouth of Henrys Fork was estimated by using data from U.S. Geological Survey streamflow-gaging station 09229500, Henrys Fork near Manila, Utah. The annual dissolved-solids load for water years 1970-2009 ranged from 18,300 tons in 1977 to 123,300 tons in 1983. Annual streamflows for this period ranged from 14,100 acre-feet in 1977 to 197,500 acre-feet in 1983. The 25-percent trimmed mean dissolved-solids load for water years 1970-2009 was 44,300 tons per year at Henrys Fork near Manila, Utah. Previous simulations using a SPAtially Referenced Regression On Watershed attributes (SPARROW) model for dissolved solids specific to water year 1991 conditions in the Upper Colorado River Basin predicted an annual dissolved-solids load of 25,000 tons for the Henrys Fork Basin upstream from Antelope Wash. On the basis of computed dissolved-solids load data from Henrys Fork near Manila, Utah, together with estimated annual dissolved-solids load from Antelope Wash and Peoples Canal, this prediction was adjusted to 37,200 tons. As determined by simulations with the Upper Colorado River Basin SPARROW model, approximately 56 percent (14,000 tons per year) of the dissolved-solids load at Henrys Fork upstream from Antelope Wash is associated with the 21,500 acres of irrigated agricultural lands in the upper Henrys Fork Basin.

  7. Process for coal liquefaction in staged dissolvers

    DOEpatents

    Roberts, George W.; Givens, Edwin N.; Skinner, Ronald W.

    1983-01-01

    There is described an improved liquefaction process by which coal is converted to a low ash and low sulfur carbonaceous material that can be used as a fuel in an environmentally acceptable manner without costly gas scrubbing equipment. In the process, coal is slurried with a pasting oil, passed through a preheater and at least two dissolvers in series in the presence of hydrogen-rich gases at elevated temperatures and pressures. Solids, including mineral ash and unconverted coal macerals, are separated from the condensed reactor effluent. In accordance with the improved process, the first dissolver is operated at a higher temperature than the second dissolver. This temperature sequence produces improved product selectivity and permits the incorporation of sufficient hydrogen in the solvent for adequate recycle operations.

  8. Wastewater treatment with zero dissolved oxygen

    SciTech Connect

    Hirl, P.J.

    1998-07-01

    Many wastewater treatment plants operate their biological reactors inefficiently because the aeration is not adjusted so that the oxygen supply rate equals the microbial oxygen demand in real times. Tapered aeration systems vary aeration based on the oxygen demand profile but these systems are static. Dynamic oxygen control systems have been successful but do not operate at low dissolved oxygen concentrations. The purpose of the research described is to develop a control system and reactor operating strategies to dynamically change the aeration rate to match the oxygen uptake rate while maintaining the dissolve oxygen concentration less than 0.5 mg/L. Though, low dissolved oxygen operation can reduce the rate of carbon degradation and/or promote filamentous bulking, it also maximizes the oxygen transfer rate and can promote simultaneous nitrification and denitrification. Development and testing of a control system and operating strategies at the bench scale is in progress.

  9. A Quantitative Evaluation of Dissolved Oxygen Instrumentation

    NASA Technical Reports Server (NTRS)

    Pijanowski, Barbara S.

    1971-01-01

    The implications of the presence of dissolved oxygen in water are discussed in terms of its deleterious or beneficial effects, depending on the functional consequences to those affected, e.g., the industrialist, the oceanographer, and the ecologist. The paper is devoted primarily to an examination of the performance of five commercially available dissolved oxygen meters. The design of each is briefly reviewed and ease or difficulty of use in the field described. Specifically, the evaluation program treated a number of parameters and user considerations including an initial check and trial calibration for each instrument and a discussion of the measurement methodology employed. Detailed test results are given relating to the effects of primary power variation, water-flow sensitivity, response time, relative accuracy of dissolved-oxygen readout, temperature accuracy (for those instruments which included this feature), error and repeatability, stability, pressure and other environmental effects, and test results obtained in the field. Overall instrument performance is summarized comparatively by chart.

  10. Release of biodegradable dissolved organic matter from ancient sedimentary rocks

    NASA Astrophysics Data System (ADS)

    Schillawski, Sarah; Petsch, Steven

    2008-09-01

    Sedimentary rocks contain the largest mass of organic carbon on Earth, yet these reservoirs are not well integrated into modern carbon budgets. Here we describe the release of dissolved organic matter (DOM) from OM-rich sedimentary rocks under simulated weathering conditions. Results from column experiments demonstrate slow, sustained release of DOM from ancient sedimentary rocks under simulated weathering conditions. 1H-NMR analysis of shale-derived DOM reveals a highly aliphatic, carbohydrate-poor material distinct from other natural DOM pools. Shale-derived DOM is rapidly assimilated and biodegraded by aerobic heterotrophic bacteria. Consequently, no compositional signature of shale-derived DOM other than 14C-depletion is likely to persist in rivers or other surface reservoirs. Combined, these efforts show that dissolution provides a mechanism for the conversion of refractory kerogen into labile biomass, linking rock weathering with sedimentary OM oxidation and the delivery of aged OM to rivers and ocean margins.

  11. Dissolving process of a cellulose bunch in ionic liquids: a molecular dynamics study.

    PubMed

    Li, Yao; Liu, Xiaomin; Zhang, Suojiang; Yao, Yingying; Yao, Xiaoqian; Xu, Junli; Lu, Xingmei

    2015-07-21

    In recent years, a variety of ionic liquids (ILs) were found to be capable of dissolving cellulose and mechanistic studies were also reported. However, there is still a lack of detailed information at the molecular level. Here, long time molecular dynamics simulations of cellulose bunch in 1-ethyl-3-methylimidazolium acetate (EmimAc), 1-ethyl-3-methylimidazolium chloride (EmimCl), 1-butyl-3-methylimidazolium chloride (BmimCl) and water were performed to analyze the inherent interaction and dissolving mechanism. Complete dissolution of the cellulose bunch was observed in EmimAc, while little change took place in EmimCl and BmimCl, and nothing significant happened in water. The deconstruction of the hydrogen bond (H-bond) network in cellulose was found and analyzed quantitatively. The synergistic effect of cations and anions was revealed by analyzing the whole dissolving process. Initially, cations bind to the side face of the cellulose bunch and anions insert into the cellulose strands to form H-bonds with hydroxyl groups. Then cations start to intercalate into cellulose chains due to their strong electrostatic interaction with the entered anions. The H-bonds formed by Cl(-) cannot effectively separate the cellulose chain and that is the reason why EmimCl and BmimCl dissolve cellulose more slowly. These findings deepen people's understanding on how ILs dissolve cellulose and would be helpful for designing new efficient ILs to dissolve cellulose. PMID:26095890

  12. EXPERIMENTAL STUDY TO EVALUATE CORROSION OF THE F-CANYON DISSOLVER DURING THEUNIRRADIATED MARK-42 CAMPAIGN

    SciTech Connect

    Mickalonis, J; Kerry Dunn, K

    1999-08-01

    Unirradiated Mark 42 fuel tubes are to be dissolved in an upcoming campaign in F-canyon. Savannah River Technology Center (SRTC)/Chemical & Hydrogen Technology Section (CHTS) identified a flow sheet for the dissolution of these Mark 42 fuel tubes which required a more aggressive dissolver solution than previously required for irradiated Mark 42 fuel tubes. Subsequently, SRTC/MTS was requested to develop and perform a corrosion testing program to assess the impact of new flow sheets on corrosion of the dissolver wall. The two primary variables evaluated were the fluoride and aluminum concentrations of the dissolver solution. Fluoride was added as Calcium Fluoride (CaF{sub 2}) while the aluminum was added either as metallic aluminum, which was subsequently dissolved, or as the chemical aluminum nitrate (Al(NO{sub 3}){sub 3}). The dissolved aluminum metal was used to simulate the dissolution of the aluminum from the Mark 42 cladding and fuel matrix. Solution composition for the corrosion tests bracketed the flow sheet for the Mark 42. Corrosion rates of AISI Type 304 stainless steel coupons, both welded and non-welded coupons, were calculated from measured weight losses and post-test concentrations of soluble Fe, Cr and Ni. The corrosion rates, which ranged between 2.7 and 32.5 mpy, were calculated from both the one day and the one week weight losses. These corrosion rates indicated a relatively mild corrosion on the dissolver vessel. The welded coupons consistently had a higher corrosion rate than the non-welded coupons. The difference between the two decreased as the solution aggressiveness decreased. In these test solutions, aggressiveness corresponded with the fluoride concentration. Based on the results of this study, any corrosion occurring during the Mark 42 Campaign is not expected to have a deleterious effect on the dissolver vessel.

  13. Evaluation of a vertical continuous centrifuge for clarification of HTGR dissolver slurries

    SciTech Connect

    Olguin, L.J.

    1980-03-01

    A series of statistically designed centrifuge performance tests was conducted to evaluate the solid-liquid separation efficiency of a vertical continuous centrifuge. Test results show that 100% of the particles greater than 4 microns in diameter were removed from simulated HTGR fuel reprocessing dissolver solutions. Centrifugal force and liquid density are the principal variables affecting separation efficiency.

  14. Identification of dissolved-constituent sources in mine-site ground water using batch mixing

    USGS Publications Warehouse

    Clark, Gregory M.; Williams, Robert S., Jr.

    1991-01-01

    Batch-mixing experiments were used to help identify lithologic and mineralogic sources of increased concentrations of dissolved solids in water affected by surface coal mining in northwestern Colorado. Ten overburden core samples were analyzed for mineral composition and mixed with distilled water for 90 days until mineral-water equilibrium was reached. Between one day and 90 days after initial contact, specific conductance in the sample mixtures had a median increase of 306 percent. Dissolved-solids concentrations ranged from 200 to 8,700 mg/L in water samples extracted from the mixtures after 90 days. Mass-balance simulations were conducted using the geochemical models BALANCE and WATEQF to quantify mineral-water interactions occurring in five selected sample mixtures and in water collected from a spring at a reclaimed mine site. The spring water is affected by mineral-water interactions occurring in all of the lithologic units comprising the overburden. Results of the simulations indicate that oxidation of pyrite, dissolution of dolomite, gypsum, and epsomite, and cation-exchange reactions are the primary mineral-water interactions occurring in the overburden. Three lithologic units in the overburden (a coal, a sandstone, and a shale) probably contribute most of the dissolved solids to the spring water. Water sample extracts from mixtures using core from these three units accounted for 85 percent of the total dissolved solids in the 10 sample extracts. Other lithologic units in the over-burden probably contribute smaller quantities of dissolved solids to the spring water.

  15. DISSOLVED OXYGEN IMPACT FROM URBAN STORM RUNOFF

    EPA Science Inventory

    The primary objective of the research reported here is to determine if on a national basis a correlation exists between strength of dissolved oxygen (DO) deficits and the presence of rainfall and/or storm runoff downstream of urban areas. A secondary objective is to estimate the ...

  16. Modeling Fish Growth in Low Dissolved Oxygen

    ERIC Educational Resources Information Center

    Neilan, Rachael Miller

    2013-01-01

    This article describes a computational project designed for undergraduate students as an introduction to mathematical modeling. Students use an ordinary differential equation to describe fish weight and assume the instantaneous growth rate depends on the concentration of dissolved oxygen. Published laboratory experiments suggest that continuous…

  17. Dissolving microneedles for transdermal drug delivery.

    PubMed

    Lee, Jeong W; Park, Jung-Hwan; Prausnitz, Mark R

    2008-05-01

    Microfabrication technology has been adapted to produce micron-scale needles as a safer and painless alternative to hypodermic needle injection, especially for protein biotherapeutics and vaccines. This study presents a design that encapsulates molecules within microneedles that dissolve within the skin for bolus or sustained delivery and leave behind no biohazardous sharp medical waste. A fabrication process was developed based on casting a viscous aqueous solution during centrifugation to fill a micro-fabricated mold with biocompatible carboxymethylcellulose or amylopectin formulations. This process encapsulated sulforhodamine B, bovine serum albumin, and lysozyme; lysozyme was shown to retain full enzymatic activity after encapsulation and to remain 96% active after storage for 2 months at room temperature. Microneedles were also shown to be strong enough to insert into cadaver skin and then to dissolve within minutes. Bolus delivery was achieved by encapsulating molecules just within microneedle shafts. For the first time, sustained delivery over hours to days was achieved by encapsulating molecules within the microneedle backing, which served as a controlled release reservoir that delivered molecules by a combination of swelling the backing with interstitial fluid drawn out of the skin and molecule diffusion into the skin via channels formed by dissolved microneedles. We conclude that dissolving microneedles can be designed to gently encapsulate molecules, insert into skin, and enable bolus or sustained release delivery. PMID:18261792

  18. REMOVING DISSOLVED INORGANIC CONTAMINANTS FROM WATER

    EPA Science Inventory

    Dissolved inorganic contaminants in water can be cationic, anionic, or neutral forms of ions, atoms, or molecules of any element in the periodic table. The article describes the physicochemical treatment processes typically used to remove the more common inorganic contaminants fr...

  19. Contaminant-mediated photobleaching of wetland chromophoric dissolved organic matter.

    PubMed

    Langlois, Maureen C; Weavers, Linda K; Chin, Yu-Ping

    2014-09-20

    Photolytic transformation of organic contaminants in wetlands can be mediated by chromophoric dissolved organic matter (CDOM), which in turn can lose its reactivity from photobleaching. We collected water from a small agricultural wetland (Ohio), Kawai Nui Marsh (Hawaii), the Everglades (Florida), and Okefenokee Swamp (Georgia) to assess the effect of photobleaching on the photofate of two herbicides, acetochlor and isoproturon. Analyte-spiked water samples were irradiated using a solar simulator and monitored for changes in CDOM light absorbance and dissolved oxygen. Photobleaching did not significantly impact the indirect photolysis rates of either herbicide over 24 hours of irradiation. Surprisingly, the opposite effect was observed with isoproturon, which accelerated DOM photobleaching. This phenomenon was more pronounced in higher-CDOM waters, and we believe that the redox pathway between triplet-state CDOM and isoproturon may be responsible for our observations. By contrast, acetochlor indirect photolysis was dependent on reaction with the hydroxyl radical and did not accelerate photobleaching of wetland water as much as isoproturon. Finally, herbicide indirect photolysis rate constants did not correlate strongly to any one chemical or optical property of the sampled waters. PMID:24828085

  20. Photo-lability of deep ocean dissolved black carbon

    NASA Astrophysics Data System (ADS)

    Stubbins, A.; Niggemann, J.; Dittmar, T.

    2012-05-01

    Dissolved black carbon (DBC), defined here as condensed aromatics isolated from seawater via PPL solid phase extraction and quantified as benzenepolycarboxylic acid (BPCA) oxidation products, is a significant component of the oceanic dissolved organic carbon (DOC) pool. These condensed aromatics are widely distributed in the open ocean and appear to be tens of thousands of years old. As such DBC is regarded as highly refractory. In the current study, the photo-lability of DBC, DOC and coloured dissolved organic matter (CDOM; ultraviolet-visible absorbance) were determined over the course of a 28 day irradiation of North Atlantic Deep Water under a solar simulator. During the irradiation DBC fell from 1044 ± 164 nM-C to 55 ± 15 nM-C, a 20-fold decrease in concentration. Dissolved black carbon photo-degradation was more rapid and more extensive than for bulk CDOM and DOC. The concentration of DBC correlated with CDOM absorbance and the quality of DBC indicated by the ratios of different BPCAs correlated with CDOM absorbance spectral slope, suggesting the optical properties of CDOM may provide a proxy for both DBC concentrations and quality in natural waters. Further, the photo-lability of components of the DBC pool increased with their degree of aromatic condensation. These trends indicate that a continuum of compounds of varying photo-lability exists within the marine DOC pool. In this continuum, photo-lability scales with aromatic character, specifically the degree of condensation. Scaling the rapid photo-degradation of DBC to rates of DOC photo-mineralisation for the global ocean leads to an estimated photo-chemical half-life for oceanic DBC of less than 800 years. This is more than an order of magnitude shorter than the apparent age of DBC in the ocean. Consequently, photo-degradation is posited as the primary sink for oceanic DBC and the apparent survival of DBC molecules in the oceans for millennia appears to be facilitated not by their inherent inertness but

  1. Predicting dissolved organic nitrogen export from a drained loblolly pine plantation

    NASA Astrophysics Data System (ADS)

    Tian, Shiying; Youssef, Mohamed A.; Skaggs, R. Wayne; Chescheir, G. M.; Amatya, Devendra M.

    2013-04-01

    Dissolved organic nitrogen (DON) export from terrestrial ecosystems influences the ecology of receiving surface waters. The soil carbon (C) and nitrogen (N) model, DRAINMOD-N II, was modified to simulate key processes associated with DON transformations and transport in the soil profile. DON production is modeled by tracking dynamic C:N ratios of dissolved organic matter originating from various organic matter pools. The Langmuir isotherm was used to quantify the assumed instantaneous equilibrium between potentially soluble organic N in solid and aqueous phases. DON transport with soil water was simulated using a numerical solution to the advection-dispersion reaction equation. The modified model was used for simulating temporal variations of DON export from three loblolly pine (Pinus taeda L.) plantations located in eastern North Carolina. Results showed that the model can accurately predict DON export dynamics during storm events with Nash-Sutcliffe efficiency (E) of 0.5, seasonal DON losses with E above 0.6, and annual DON losses with E above 0.7. In addition to the well-recognized role of hydrological processes, reasonable quantifications of the seasonal changes in the potentially soluble soil organic matter, the DON sorption to soil particles, and the dynamic C:N ratios of dissolved organic matter were found to be essential for mechanistic representation of DON export dynamics. Specifically, adapting the dynamic C:N ratios enabled the model to reasonably describe the temporal variations of correlations between DON and dissolved organic carbon in drainage water.

  2. Distribution of dissolved silver in marine waters

    NASA Astrophysics Data System (ADS)

    Barriada, J. L.; Achterberg, E. P.; Tappin, A.; Truscott, J.

    2003-04-01

    Silver is one of the most toxic heavy metals, surpassed only by mercury [1-3]. Monitoring of dissolved silver concentrations in natural waters is therefore of great importance. The determination of dissolved silver in waters is not without challenges, because of its low (picomolar) concentrations. Consequently, there are only a few reported studies in marine waters, which have been performed in USA [4-6] and Japan [7]. The analytical techniques used in the reported studies for the determination of silver in seawater were Graphite Furnace Atomic Absorption Spectroscopy (GFAAS) after solvent extraction [2,4,5], and Inductively Coupled Plasma Mass Spectrometry (ICP-MS) after solvent extraction or solid phase extraction [7,8]. In this contribution, we will present an optimised Magnetic Sector (MS) ICP-MS technique for the determination of dissolved silver in marine waters. The MS-ICP-MS method used anion exchange column to preconcentrate silver from saline waters, and to remove the saline matrix. The ICP-MS method has been used successfully to determine total dissolved silver in estuarine and oceanic samples. Bibliography 1. H. T. Ratte, Environ. Toxicol. Chem. 1999, 18: p. 89-108. 2. R. T. Herrin, A. W. Andren and D. E. Armstrong, Environ. Sci. Technol. 2001, 35: 1953-1958. 3. D. E. Schildkraut, P. T. Dao, J. P. Twist, A. T. Davis and K. A. Robillard, Environ. Toxicol. Chem. 1998, 17: 642-649. 4. E. Breuer, S. A. Sanudo-Wilhelmy and R. C. Aller, Estuaries. 1999, 22:603-615. 5. A. R. Flegal, S. A. Sanudowilhelmy and G. M. Scelfo, Mar. Chem. 1995, 49: 315-320. 6. S. N. Luoma, Y. B. Ho and G. W. Bryan, Mar. Pollut. Bull. 1995, 31: 44-54. 7. Y. Zhang, H. Amakawa and Y. Nozaki, Mar. Chem. 2001, 75: 151-163. 8. L. Yang and R. E. Sturgeon, J. Anal. At. Spectrom. 2002, 17: 88-93.

  3. Treatment of SRS Tank 48H Simulants Using Fenton's Reagent

    SciTech Connect

    Taylor, PA

    2003-11-18

    High-level-waste Tank 48H at the Savannah River Site (SRS) contains about 50,000 lb of tetraphenylborate (TPB), which must be destroyed to return the tank to active service. Laboratory-scale tests were conducted to evaluate the use of Fenton's Reagent (hydrogen peroxide and a metal catalyst) to treat simulants of the Tank 48H waste. Samples of the treated slurry and the off-gas were analyzed to determine the reaction products. Process parameters developed earlier by AEA Technology were used for these tests; namely (for 500 mL of waste simulant), reduce pH to 7.5 with nitric acid, heat to boiling, add hydrogen peroxide at 1 mL/min for 1 h, reduce pH to 3.5, and add the remaining peroxide at 2 mL/min. These parameters were developed to minimize the formation of tarry materials during the early part of the reaction and to minimize the concentration of total organic carbon in the final treated slurry. The treated samples contained low concentrations of total organic carbon (TOC) and no detectable TPB. Tests using a mixture of iron and copper salts as the Fenton's catalyst had a lower TOC concentration in the final treated slurry than did tests that used a copper-only catalyst. TPB is known to hydrolyze to benzene, particularly at high temperature and low pH, and copper is known to increase the rate of hydrolysis. Significant amounts of benzene were present in the off-gas from the tests, especially during the early portion of the treatment, indicating that the hydrolysis reaction was occurring in parallel with the oxidation of the TPB by Fenton's reagent. For the reaction conditions used in these tests, approximately equal fractions of the TPB were converted to benzene and carbon dioxide. Minimizing the formation of benzene is important to SRS personnel; however, this consideration was not addressed in the AEA-recommended parameters, since they did not analyze for benzene in the off-gas. Smaller amounts of carbon monoxide and other organics were also produced. One test

  4. Key results from SB8 simulant flowsheet studies

    SciTech Connect

    Koopman, D. C.

    2013-04-26

    Key technically reviewed results are presented here in support of the Defense Waste Processing Facility (DWPF) acceptance of Sludge Batch 8 (SB8). This report summarizes results from simulant flowsheet studies of the DWPF Chemical Process Cell (CPC). Results include: Hydrogen generation rate for the Sludge Receipt and Adjustment Tank (SRAT) and Slurry Mix Evaporator (SME) cycles of the CPC on a 6,000 gallon basis; Volume percent of nitrous oxide, N2O, produced during the SRAT cycle; Ammonium ion concentrations recovered from the SRAT and SME off-gas; and, Dried weight percent solids (insoluble, soluble, and total) measurements and density.

  5. Investigating Students' Understanding of the Dissolving Process

    NASA Astrophysics Data System (ADS)

    Naah, Basil M.; Sanger, Michael J.

    2013-04-01

    In a previous study, the authors identified several student misconceptions regarding the process of dissolving ionic compounds in water. The present study used multiple-choice questions whose distractors were derived from these misconceptions to assess students' understanding of the dissolving process at the symbolic and particulate levels. The symbolic-level questions were based on balanced equations, and the particulate-level questions used multiple-choice questions involving dynamic animations or static pictures. This paper analyzes students' responses to these questions to look for associations among four variables—Answer (the correct answer and three misconceptions), Representation (symbolic or particulate question), Visualization (static or animated pictures), and Representation Order (symbolic questions before or after the particulate questions). The results indicate that the correct answer and the acid-base misconception were more popular than the ion-pair or subscript error misconceptions, the ion-pair misconception was more popular for the particulate questions than the symbolic questions, and that participants were more likely to select the correct answer when viewing static particulate questions compared to animated particulate questions, especially if the particulate questions are seen first. These results suggest that the animated motion of dissolving these compounds in water may be distracting for students.

  6. SUSPENDED AND DISSOLVED SOLIDS EFFECTS ON FRESHWATER BIOTA: A REVIEW

    EPA Science Inventory

    It is widely recognized that suspended and dissolved solids in lakes, rivers, streams, and reservoirs affect water quality. In this report the research needs appropriate to setting freshwater quality criteria or standards for suspended solids (not including bedload) and dissolved...

  7. 7 CFR 760.908 - Deceased individuals or dissolved entities.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... dissolved entity must be provided. (c) If a participant is now a dissolved general partnership or joint venture, all members of the general partnership or joint venture at the time of dissolution or their...

  8. 7 CFR 760.908 - Deceased individuals or dissolved entities.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... dissolved entity must be provided. (c) If a participant is now a dissolved general partnership or joint venture, all members of the general partnership or joint venture at the time of dissolution or their...

  9. FINAL REPORT INTEGRATED DM1200 MELTER TESTING USING AZ 102 AND C 106/AY-102 HLW SIMULANTS: HLW SIMULANT VERIFICATION VSL-05R5800-1 REV 0 6/27/05

    SciTech Connect

    KRUGER AA; MATLACK KS; GONG W; BARDAKCI T; D'ANGELO NA; BRANDYS M; KOT WK; PEGG IL

    2011-12-29

    The principal objectives of the DM1200 melter tests were to determine the effects of feed rheology, feed solid content, and bubbler configuration on glass production rate and off-gas system performance while processing the HLW AZ-101 and C-106/AY-102 feed compositions; characterize melter off-gas emissions; characterize the performance of the prototypical off-gas system components, as well as their integrated performance; characterize the feed, glass product, and off-gas effluents; and perform pre- and post test inspections of system components. The specific objectives (including test success criteria) of this testing, along with how each objective was met, are outlined in a table. The data provided in this Final Report address the impacts of HLW melter feed rheology on melter throughput and validation of the simulated HLW melter feeds. The primary purpose of this testing is to further validate/verify the HLW melter simulants that have been used for previous melter testing and to support their continued use in developing melter and off-gas related processing information for the Project. The primary simulant property in question is rheology. Simulants and melter feeds used in all previous melter tests were produced by direct addition of chemicals; these feed tend to be less viscous than rheological the upper-bound feeds made from actual wastes. Data provided here compare melter processing for the melter feed used in all previous DM100 and DM1200 tests (nominal melter feed) with feed adjusted by the feed vendor (NOAH Technologies) to be more viscous, thereby simulating more closely the upperbounding feed produced from actual waste. This report provides results of tests that are described in the Test Plan for this work. The Test Plan is responsive to one of several test objectives covered in the WTP Test Specification for this work; consequently, only part of the scope described in the Test Specification was addressed in this particular Test Plan. For the purpose of

  10. Assessing the Effects of Water Rights Purchases on Dissolved Oxygen, Stream Temperatures, and Fish Habitat

    NASA Astrophysics Data System (ADS)

    Mouzon, N. R.; Null, S. E.

    2014-12-01

    Human impacts from land and water development have degraded water quality and altered the physical, chemical, and biological integrity of Nevada's Walker River. Reduced instream flows and increased nutrient concentrations affect native fish populations through warm daily stream temperatures and low nightly dissolved oxygen concentrations. Water rights purchases are being considered to maintain instream flows, improve water quality, and enhance habitat for native fish species, such as Lahontan cutthroat trout. This study uses the River Modeling System (RMSv4), an hourly, physically-based hydrodynamic and water quality model, to estimate streamflows, temperatures, and dissolved oxygen concentrations in the Walker River. We simulate thermal and dissolved oxygen changes from increased streamflow to prioritize the time periods and locations that water purchases most enhance native trout habitat. Stream temperatures and dissolved oxygen concentrations are proxies for trout habitat. Monitoring results indicate stream temperature and dissolved oxygen limitations generally exist in the 115 kilometers upstream of Walker Lake (about 37% of the study area) from approximately May through September, and this reach currently acts as a water quality barrier for fish passage.

  11. Total dissolvable and dissolved iron isotopes in the water column of the Peru upwelling regime

    NASA Astrophysics Data System (ADS)

    Chever, Fanny; Rouxel, Olivier J.; Croot, Peter L.; Ponzevera, Emmanuel; Wuttig, Kathrin; Auro, Maureen

    2015-08-01

    Vertical distributions of iron (Fe) concentrations and isotopes were determined in the total dissolvable and dissolved pools in the water column at three coastal stations located along the Peruvian margin, in the core of the Oxygen Minimum Zone (OMZ). The shallowest station 121 (161 m total water depth) was characterized by lithogenic input from the continental plateau, yielding concentrations as high as 456 nM in the total dissolvable pool. At the 2 other stations (stations 122 and 123), Fe concentrations of dissolved and total dissolvable pools exhibited maxima in both surface and deep layers. Fe isotopic composition (δ56Fe) showed a fractionation toward lighter values for both physical pools throughout the water column for all stations with minimum values observed for the surface layer (between -0.64 and -0.97‰ at 10-20 m depth) and deep layer (between -0.03 and -1.25‰ at 160-300 m depth). An Fe isotope budget was established to determine the isotopic composition of the particulate pool. We observed a range of δ56Fe values for particulate Fe from +0.02 to -0.87‰, with lightest values obtained at water depth above 50 m. Such light values in the both particulate and dissolved pools suggest sources other than atmospheric dust deposition in the surface ocean, including lateral transport of isotopically light Fe. Samples collected at station 122 closest to the sediment show the lightest isotope composition in the dissolved and the particulate pools (-1.25 and -0.53‰ respectively) and high Fe(II) concentrations (14.2 ± 2.1 nM) consistent with a major reductive benthic Fe sources that is transferred to the ocean water column. A simple isotopic model is proposed to link the extent of Fe(II) oxidation and the Fe isotope composition of both particulate and dissolved Fe pools. This study demonstrates that Fe isotopic composition in OMZ regions is not only affected by the relative contribution of reductive and non-reductive shelf sediment input but also by

  12. Dissolved gas transport in the presence of a trapped gas phase: Experimental evaluation of a two-dimensional kinetic model

    SciTech Connect

    Donaldson, J.H.; Istok, J.D.; O`Reilly, K.T.

    1998-01-01

    Quantitative information on dissolved gas transport in ground water aquifers is needed for a variety of site characterization and remedial design applications. The objective of this study was to gain further understanding of dissolved gas transport in the presence of trapped gas in the pore space of an otherwise water saturated porous medium, using a combination of laboratory experiments and numerical modeling. Transport experiments were conducted in a large-scale laboratory physical aquifer model containing a homogeneous sandpack. Tracer (Br{sup {minus}}) and dissolved gas (O{sub 2} or H{sub 2}) plumes were created using a two-well injection/extraction scheme and then were allowed to drift in a uniform flow field. Plume locations and shapes were monitored by measuring tracer and dissolved gas concentrations as a function of position within the sandpack and time. In all experiments, partitioning of the dissolved gases between the mobile ground water and stationary trapped gas phases resulted in substantial retardation and tailing of the dissolved O{sub 2} and H{sub 2} plumes relative to the Br{sup {minus}} plumes. Most observed plume features could be reproduced in simulations performed with a numerical model that combined the advection-dispersion equation with diffusion controlled mass transfer of dissolved gas between the mobile aqueous and stationary trapped gas phases. Fitted values of the volumetric trapped gas content and mass transfer coefficient ranged from 0.04 to 0.08 and from 10{sup {minus}6} to 10{sup {minus}5} sec{sup {minus}1}, respectively. Sensitivity analyses were used to examine how systematic variations in these parameters would be expected to affect dissolved gas transport under a range of potential field conditions. The experimental and modeling results indicate that diffusion controlled mass transfer should be considered when predicting dissolved gas transport in ground water aquifers in the presence of trapped gas.

  13. Novel approach of aceclofenac fast dissolving tablet.

    PubMed

    Dave, Vivek; Yadav, Sachdev; Sharma, Swapnil; Vishwakarma, Pushpendra; Ali, Nasir

    2015-01-01

    Fast disintegrating tablets (FDTs) have received ever increasing demand during the last decade, and the field has become a hastily growing area in the pharmaceutical industry. Upon introduction into the mouth, these tablets dissolve or disintegrate in the mouth in the absence of additional water for easy administration of active pharmaceutical ingredients. Aceclofenac, an NSAID, has been recommended orally for the treatment of bone and connective tissue disorder and thus the formulation of the same resulted in development of several FDT technologies. The present aim is to formulate a tablet which disintegrate and dissolve rapidly and give its rapid onset of action: analgesic, antipyretic and anti-inflammatory action. Besides, the conventional tablets also show poor patient compliance an attempt had been made to formulate for FDT of aceclofenac by using various super disintegrants like sodium starch glycolate, croscarmellose sodium and crosspovidone (polyplasdone XL) and PEG 6000 followed by novel technique. The tablets were evaluated for friability, hardness, weight variation, disintegration time, wetting time, in vitro dissolution studies and drug content studies. It was concluded that the batch which was prepared by using combination of crosspovidone and sodium starch glycolate as a super disintegrant shows excellent disintegration time, enhance dissolution rate, taste masking and hence lead to improve efficacy and bioavailability of drug. PMID:25553683

  14. Photoluminescent detection of dissolved underwater trace explosives.

    PubMed

    Langston, Tye

    2010-01-01

    A portable, rapid, and economical method for in situ trace explosive detection in aqueous solutions was demonstrated using photoluminescence. Using europium/ thenoyltrifluoroacetone as the reagent, dissolved nitroglycerin was fluorescently tagged and detected in seawater solutions without sample preparation, drying, or preconcentration. The chemical method was developed in a laboratory setting and demonstrated in a flow-through configuration using lightweight, inexpensive, commercial components by directly injecting the reagents into a continually flowing seawater stream using a small amount of organic solvent (approximately 8% of the total solution). Europium's vulnerability to vibrational fluorescence quenching by water provided the mode of detection. Without nitroglycerin in the seawater solution, the reagent's fluorescence was quenched, but when dissolved nitroglycerin was present, it displaced the water molecules from the europium/thenoyltrifluoroacetone compound and restored fluorescence. This effort focused on developing a seawater sensor, but performance comparisons were made to freshwater. The method was found to perform better in freshwater and it was shown that certain seawater constituents (such as calcium) have an adverse impact. However, the concentrations of these constituents are not expected to vary significantly from the natural seawater used herein. PMID:20364240

  15. DISSOLVED CONCENTRATION LIMITS OF RADIOACTIVE ELEMENTS

    SciTech Connect

    NA

    2004-11-22

    The purpose of this study is to evaluate dissolved concentration limits (also referred to as solubility limits) of elements with radioactive isotopes under probable repository conditions, based on geochemical modeling calculations using geochemical modeling tools, thermodynamic databases, field measurements, and laboratory experiments. The scope of this modeling activity is to predict dissolved concentrations or solubility limits for 14 elements with radioactive isotopes (actinium, americium, carbon, cesium, iodine, lead, neptunium, plutonium, protactinium, radium, strontium, technetium, thorium, and uranium) important to calculated dose. Model outputs for uranium, plutonium, neptunium, thorium, americium, and protactinium are in the form of tabulated functions with pH and log (line integral) CO{sub 2} as independent variables, plus one or more uncertainty terms. The solubility limits for the remaining elements are either in the form of distributions or single values. The output data from this report are fundamental inputs for Total System Performance Assessment for the License Application (TSPA-LA) to determine the estimated release of these elements from waste packages and the engineered barrier system. Consistent modeling approaches and environmental conditions were used to develop solubility models for all of the actinides. These models cover broad ranges of environmental conditions so that they are applicable to both waste packages and the invert. Uncertainties from thermodynamic data, water chemistry, temperature variation, and activity coefficients have been quantified or otherwise addressed.

  16. Basin-scale transport of hydrothermal dissolved metals across the South Pacific Ocean.

    PubMed

    Resing, Joseph A; Sedwick, Peter N; German, Christopher R; Jenkins, William J; Moffett, James W; Sohst, Bettina M; Tagliabue, Alessandro

    2015-07-01

    Hydrothermal venting along mid-ocean ridges exerts an important control on the chemical composition of sea water by serving as a major source or sink for a number of trace elements in the ocean. Of these, iron has received considerable attention because of its role as an essential and often limiting nutrient for primary production in regions of the ocean that are of critical importance for the global carbon cycle. It has been thought that most of the dissolved iron discharged by hydrothermal vents is lost from solution close to ridge-axis sources and is thus of limited importance for ocean biogeochemistry. This long-standing view is challenged by recent studies which suggest that stabilization of hydrothermal dissolved iron may facilitate its long-range oceanic transport. Such transport has been subsequently inferred from spatially limited oceanographic observations. Here we report data from the US GEOTRACES Eastern Pacific Zonal Transect (EPZT) that demonstrate lateral transport of hydrothermal dissolved iron, manganese, and aluminium from the southern East Pacific Rise (SEPR) several thousand kilometres westward across the South Pacific Ocean. Dissolved iron exhibits nearly conservative (that is, no loss from solution during transport and mixing) behaviour in this hydrothermal plume, implying a greater longevity in the deep ocean than previously assumed. Based on our observations, we estimate a global hydrothermal dissolved iron input of three to four gigamoles per year to the ocean interior, which is more than fourfold higher than previous estimates. Complementary simulations with a global-scale ocean biogeochemical model suggest that the observed transport of hydrothermal dissolved iron requires some means of physicochemical stabilization and indicate that hydrothermally derived iron sustains a large fraction of Southern Ocean export production. PMID:26156374

  17. Net methylation of mercury in estuarine sediment microcosms amended with dissolved, nanoparticulate, and microparticulate mercuric sulfides.

    PubMed

    Zhang, Tong; Kucharzyk, Katarzyna H; Kim, Bojeong; Deshusses, Marc A; Hsu-Kim, Heileen

    2014-08-19

    The production of methylmercury (MeHg) by anaerobic microorganisms depends in part on the speciation and bioavailability of inorganic mercury to these organisms. Our previous work with pure cultures of methylating bacteria has demonstrated that the methylation potential of mercury decreased during the aging of mercuric sulfides (from dissolved to nanoparticulate and microcrystalline HgS). The objective of this study was to understand the relationship between mercury sulfide speciation and methylation potential in experiments that more closely simulate the complexity of sediment settings. The study involved sediment slurry microcosms that represented a spectrum of salinities in an estuary and were each amended with different forms of mercuric sulfides: dissolved Hg and sulfide, nanoparticulate HgS (3-4 nm in diameter), and microparticulate HgS (>500 nm). The results indicated that net MeHg production was influenced by both the activity of sulfate-reducing microorganisms (roughly represented by the rate of sulfate loss) and the bioavailability of mercury. In the presence of abundant sulfate and carbon sources (supporting relatively high microbial activity), net MeHg production in the slurries amended with dissolved Hg was greater than in slurries amended with nano-HgS, similar to previous experiments with pure bacterial cultures. In microcosms with minimal microbial activity (indicated by low rates of sulfate loss), the addition of either dissolved Hg or nano-HgS resulted in similar amounts of net MeHg production. For all slurries receiving micro-HgS, MeHg production did not exceed abiotic controls. In slurries amended with dissolved and nano-HgS, mercury was mainly partitioned to bulk-scale mineral particles and colloids, indicating that Hg bioavailability was not simply related to dissolved Hg concentration or speciation. Overall, the results suggest that models for mercury methylation potential in the environment will need to balance the relative contributions of

  18. Basin-scale transport of hydrothermal dissolved metals across the South Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Resing, Joseph A.; Sedwick, Peter N.; German, Christopher R.; Jenkins, William J.; Moffett, James W.; Sohst, Bettina M.; Tagliabue, Alessandro

    2015-07-01

    Hydrothermal venting along mid-ocean ridges exerts an important control on the chemical composition of sea water by serving as a major source or sink for a number of trace elements in the ocean. Of these, iron has received considerable attention because of its role as an essential and often limiting nutrient for primary production in regions of the ocean that are of critical importance for the global carbon cycle. It has been thought that most of the dissolved iron discharged by hydrothermal vents is lost from solution close to ridge-axis sources and is thus of limited importance for ocean biogeochemistry. This long-standing view is challenged by recent studies which suggest that stabilization of hydrothermal dissolved iron may facilitate its long-range oceanic transport. Such transport has been subsequently inferred from spatially limited oceanographic observations. Here we report data from the US GEOTRACES Eastern Pacific Zonal Transect (EPZT) that demonstrate lateral transport of hydrothermal dissolved iron, manganese, and aluminium from the southern East Pacific Rise (SEPR) several thousand kilometres westward across the South Pacific Ocean. Dissolved iron exhibits nearly conservative (that is, no loss from solution during transport and mixing) behaviour in this hydrothermal plume, implying a greater longevity in the deep ocean than previously assumed. Based on our observations, we estimate a global hydrothermal dissolved iron input of three to four gigamoles per year to the ocean interior, which is more than fourfold higher than previous estimates. Complementary simulations with a global-scale ocean biogeochemical model suggest that the observed transport of hydrothermal dissolved iron requires some means of physicochemical stabilization and indicate that hydrothermally derived iron sustains a large fraction of Southern Ocean export production.

  19. 40 CFR 430.40 - Applicability; description of the dissolving sulfite subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... dissolving sulfite subcategory. 430.40 Section 430.40 Protection of Environment ENVIRONMENTAL PROTECTION... CATEGORY Dissolving Sulfite Subcategory § 430.40 Applicability; description of the dissolving sulfite... at dissolving sulfite mills....

  20. 40 CFR 430.40 - Applicability; description of the dissolving sulfite subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... dissolving sulfite subcategory. 430.40 Section 430.40 Protection of Environment ENVIRONMENTAL PROTECTION... CATEGORY Dissolving Sulfite Subcategory § 430.40 Applicability; description of the dissolving sulfite... at dissolving sulfite mills....

  1. Seafloor Weathering Dependence on Temperature and Dissolved Inorganic Carbon

    NASA Astrophysics Data System (ADS)

    Abbot, D. S.; Farahat, N. X.; Archer, D. E.

    2015-12-01

    Most thinking on Earth's carbon cycle implicates silicate weathering as the dominant control of atmospheric CO2 concentration over long timescales. Recent analyses of alteration of basalt at the seafloor, however, suggest that seafloor weathering (low-temperature (<60C) chemical alteration of the upper oceanic crust due to hydrothermal seawater circulation) increases dramatically in warm, high CO2 periods of Earth's history. This raises the possibility that seafloor weathering could complement silicate weathering in maintaining Earth's long term climate stability. Moreover, seafloor weathering would be the only type of weathering available on an exoplanet entirely covered by water, so understanding how it might work is essential for understanding the habitable zones of such waterworlds. We have built a 2D numerical model of the flow of seawater through porous basalt coupled to chemical alteration reactions that can calculate alkalinity fluxes and carbonate deposition (seafloor weathering). I will present simulations in which we vary the seawater temperature and dissolved inorganic carbon concentration, which are boundary conditions to our model, over large ranges. These results will provide a constraint on the ability of seafloor weathering to act as an effective climate buffer on Earth and other planets. I can't give you a preview of the results yet because at the time of writing this abstract we haven't completed the simulations!

  2. Effluent dissolved organic nitrogen and dissolved phosphorus removal by enhanced coagulation and microfiltration.

    PubMed

    Arnaldos, Marina; Pagilla, Krishna

    2010-10-01

    Plants aiming to achieve very low effluent nutrient levels (<3 mg N/L for N, and <0.1 mg P/L for P) need to consider removal of effluent fractions hitherto not taken into account. Two of these fractions are dissolved organic nitrogen (DON) and dissolved non-reactive phosphorus (DNRP) (mainly composed of organic phosphorus). In this research, enhanced coagulation using alum (at doses commonly employed in tertiary phosphorus removal) followed by microfiltration (using 0.22 μm pore size filters) was investigated for simultaneous effluent DON and dissolved phosphorus (DP) fractions removal. At an approximate dose of 3.2 mg Al(III)/L, corresponding to 1.5 Al(III)/initial DON-N and 3.8 Al(III)/initial DP-P molar ratios, maximum simultaneous removal of DON and DP was achieved (69% for DON and 72% for DP). At this dose, residual DON and DP concentrations were found to be 0.3 mg N/L and 0.25 mg P/L, respectively. Analysis of the trends of removal revealed that the DNRP removal pattern was similar to that commonly reported for dissolved reactive phosphorus. Since this study involved intensive analytical work, a secondary objective was to develop a simple and accurate measurement protocol for determining dissolved N and P species at very low levels in wastewater effluents. The protocol developed in this study, involving simultaneous digestion for DON and DNRP species, was found to be very reliable and accurate based on the results. PMID:20643469

  3. Removal of dissolved metals by plant tissue

    SciTech Connect

    Scott, C.D. )

    1992-04-25

    Various types of microbial biomass have been shown to adsorb metals dissolved in aqueous media. It has now been demonstrated that certain plant tissues are also effective for this type of adsorption process. In particular, tomato and tobacco roots harvested from field-grown plants were shown to adsorb Sr from an aqueous solution of SrCl[sub 2]. Distribution coefficients in excess of 550 were measured and the adsorption isotherms at 25 C could be fitted to Langmuir-type expressions. The bioadsorbent could be regenerated and metals recovered by either a reduction in the pH to less than 2.0 or by use of a concentrated chloride salt solution.

  4. Method for dissolving delta-phase plutonium

    DOEpatents

    Karraker, David G.

    1992-01-01

    A process for dissolving plutonium, and in particular, delta-phase plutonium. The process includes heating a mixture of nitric acid, hydroxylammonium nitrate (HAN) and potassium fluoride to a temperature between 40.degree. and 70.degree. C., then immersing the metal in the mixture. Preferably, the nitric acid has a concentration of not more than 2M, the HAN approximately 0.66M, and the potassium fluoride 0.1M. Additionally, a small amount of sulfamic acid, such as 0.1M can be added to assure stability of the HAN in the presence of nitric acid. The oxide layer that forms on plutonium metal may be removed with a non-oxidizing acid as a pre-treatment step.

  5. Dissolved Concentration Limits of Radioactive Elements

    SciTech Connect

    Y. Chen; E.R. Thomas; F.J. Pearson; P.L. Cloke; T.L. Steinborn; P.V. Brady

    2003-06-20

    The purpose of this study is to evaluate dissolved concentration limits (also referred to as solubility limits) of radioactive elements under possible repository conditions, based on geochemical modeling calculations using geochemical modeling tools, thermodynamic databases, and measurements made in laboratory experiments and field work. The scope of this modeling activity is to predict dissolved concentrations or solubility limits for 14 radioactive elements (actinium, americium, carbon, cesium, iodine, lead, neptunium, plutonium, protactinium, radium, strontium, technetium, thorium, and uranium), which are important to calculated dose. Model outputs are mainly in the form of look-up tables plus one or more uncertainty terms. The rest are either in the form of distributions or single values. The results of this analysis are fundamental inputs for total system performance assessment to constrain the release of these elements from waste packages and the engineered barrier system. Solubilities of plutonium, neptunium, uranium, americium, actinium, thorium, protactinium, lead, and radium have been re-evaluated using the newly updated thermodynamic database (Data0.ymp.R2). For all of the actinides, identical modeling approaches and consistent environmental conditions were used to develop solubility models in this revision. These models cover broad ranges of environmental conditions so that they are applicable to both waste packages and the invert. Uncertainties from thermodynamic data, water chemistry, temperature variation, activity coefficients, and selection of solubility controlling phase have been quantified or otherwise addressed. Moreover, a new blended plutonium solubility model has been developed in this revision, which gives a mean solubility that is three orders of magnitude lower than the plutonium solubility model used for the Total System Performance Assessment for the Site Recommendation. Two alternative neptunium solubility models have also been

  6. Centrifugo-pneumatic valving utilizing dissolvable films.

    PubMed

    Gorkin, Robert; Nwankire, Charles E; Gaughran, Jennifer; Zhang, Xin; Donohoe, Gerard G; Rook, Martha; O'Kennedy, Richard; Ducrée, Jens

    2012-08-21

    In this article we introduce a novel technology that utilizes specialized water dissolvable thin films for valving in centrifugal microfluidic systems. In previous work (William Meathrel and Cathy Moritz, IVD Technologies, 2007), dissolvable films (DFs) have been assembled in laminar flow devices to form efficient sacrificial valves where DFs simply open by direct contact with liquid. Here, we build on the original DF valving scheme to leverage sophisticated, merely rotationally actuated vapour barriers and flow control for enabling comprehensive assay integration with low-complexity instrumentation on "lab-on-a-disc" platforms. The advanced sacrificial valving function is achieved by creating an inverted gas-liquid stack upstream of the DF during priming of the system. At low rotational speeds, a pocket of trapped air prevents a surface-tension stabilized liquid plug from wetting the DF membrane. However, high-speed rotation disrupts the metastable gas/liquid interface to wet the DF and thus opens the valve. By judicious choice of the radial position and geometry of the valve, the burst frequency can be tuned over a wide range of rotational speeds nearly 10 times greater than those attained by common capillary burst valves based on hydrophobic constrictions. The broad range of reproducible burst frequencies of the DF valves bears the potential for full integration and automation of comprehensive, multi-step biochemical assay protocols. In this report we demonstrate DF valving, discuss the biocompatibility of using the films, and show a potential sequential valving system including the on-demand release of on-board stored liquid reagents, fast centrifugal sedimentation and vigorous mixing; thus providing a viable basis for use in lab-on-a-disc platforms for point-of-care diagnostics and other life science applications. PMID:22692574

  7. DISSOLVED CONCENTRATION LIMITS OF RADIOACTIVE ELEMENTS

    SciTech Connect

    P. Bernot

    2005-07-13

    The purpose of this study is to evaluate dissolved concentration limits (also referred to as solubility limits) of elements with radioactive isotopes under probable repository conditions, based on geochemical modeling calculations using geochemical modeling tools, thermodynamic databases, field measurements, and laboratory experiments. The scope of this activity is to predict dissolved concentrations or solubility limits for elements with radioactive isotopes (actinium, americium, carbon, cesium, iodine, lead, neptunium, plutonium, protactinium, radium, strontium, technetium, thorium, and uranium) relevant to calculated dose. Model outputs for uranium, plutonium, neptunium, thorium, americium, and protactinium are provided in the form of tabulated functions with pH and log fCO{sub 2} as independent variables, plus one or more uncertainty terms. The solubility limits for the remaining elements are either in the form of distributions or single values. Even though selection of an appropriate set of radionuclides documented in Radionuclide Screening (BSC 2002 [DIRS 160059]) includes actinium, transport of Ac is not modeled in the total system performance assessment for the license application (TSPA-LA) model because of its extremely short half-life. Actinium dose is calculated in the TSPA-LA by assuming secular equilibrium with {sup 231}Pa (Section 6.10); therefore, Ac is not analyzed in this report. The output data from this report are fundamental inputs for TSPA-LA used to determine the estimated release of these elements from waste packages and the engineered barrier system. Consistent modeling approaches and environmental conditions were used to develop solubility models for the actinides discussed in this report. These models cover broad ranges of environmental conditions so they are applicable to both waste packages and the invert. Uncertainties from thermodynamic data, water chemistry, temperature variation, and activity coefficients have been quantified or

  8. METHOD FOR DISSOLVING LANTHANUM FLUORIDE CARRIER FOR PLUTONIUM

    DOEpatents

    Koshland, D.E. Jr.; Willard, J.E.

    1961-08-01

    A method is described for dissolving lanthanum fluoride precipitates which is applicable to lanthanum fluoride carrier precipitation processes for recovery of plutonium values from aqueous solutions. The lanthanum fluoride precipitate is contacted with an aqueous acidic solution containing dissolved zirconium in the tetravalent oxidation state. The presence of the zirconium increases the lanthanum fluoride dissolved and makes any tetravalent plutonium present more readily oxidizable to the hexavalent state. (AEC)

  9. Method for dissolving plutonium oxide with HI and separating plutonium

    DOEpatents

    Vondra, Benedict L.; Tallent, Othar K.; Mailen, James C.

    1979-01-01

    PuO.sub.2 -containing solids, particularly residues from incomplete HNO.sub.3 dissolution of irradiated nuclear fuels, are dissolved in aqueous HI. The resulting solution is evaporated to dryness and the solids are dissolved in HNO.sub.3 for further chemical reprocessing. Alternatively, the HI solution containing dissolved Pu values, can be contacted with a cation exchange resin causing the Pu values to load the resin. The Pu values are selectively eluted from the resin with more concentrated HI.

  10. Method to Estimate the Dissolved Air Content in Hydraulic Fluid

    NASA Technical Reports Server (NTRS)

    Hauser, Daniel M.

    2011-01-01

    In order to verify the air content in hydraulic fluid, an instrument was needed to measure the dissolved air content before the fluid was loaded into the system. The instrument also needed to measure the dissolved air content in situ and in real time during the de-aeration process. The current methods used to measure the dissolved air content require the fluid to be drawn from the hydraulic system, and additional offline laboratory processing time is involved. During laboratory processing, there is a potential for contamination to occur, especially when subsaturated fluid is to be analyzed. A new method measures the amount of dissolved air in hydraulic fluid through the use of a dissolved oxygen meter. The device measures the dissolved air content through an in situ, real-time process that requires no additional offline laboratory processing time. The method utilizes an instrument that measures the partial pressure of oxygen in the hydraulic fluid. By using a standardized calculation procedure that relates the oxygen partial pressure to the volume of dissolved air in solution, the dissolved air content is estimated. The technique employs luminescent quenching technology to determine the partial pressure of oxygen in the hydraulic fluid. An estimated Henry s law coefficient for oxygen and nitrogen in hydraulic fluid is calculated using a standard method to estimate the solubility of gases in lubricants. The amount of dissolved oxygen in the hydraulic fluid is estimated using the Henry s solubility coefficient and the measured partial pressure of oxygen in solution. The amount of dissolved nitrogen that is in solution is estimated by assuming that the ratio of dissolved nitrogen to dissolved oxygen is equal to the ratio of the gas solubility of nitrogen to oxygen at atmospheric pressure and temperature. The technique was performed at atmospheric pressure and room temperature. The technique could be theoretically carried out at higher pressures and elevated

  11. Relating dissolved organic matter fluorescence to functional properties

    NASA Astrophysics Data System (ADS)

    Tipping, E.; Baker, A.; Thacker, S.; Gondar, D.

    2007-12-01

    The fluorescence excitation emission matrix properties of dissolved organic matter from three rivers and one lake in NW England are analysed. Sites are sampled in duplicate and for some sites seasonally to cover variations in dissolved organic matter composition, river flow, and carbon isotopic (13C, 14C) variability. Results are compared to the functional properties of the dissolved organic matter, the functional assays provide quantitative information on light absorption, fluorescence, photochemical fading, pH buffering, copper binding, benzo[a]pyrene binding, hydrophilicity and adsorption to alumina. Fluorescence characterization of the dissolved organic matter samples demonstrates that peak C fluorescence emission wavelength, the ratio of peak T to peak C fluorescence intensity, and the fluorescence : absorbance ratio best differentiate different dissolved organic matter samples. These parameters correspond to dissolved organic matter aromaticity, the ratio of labile to recalcitrant organic matter, and dissolved organic matter molecular weight. Peak C fluorescence emission wavelength, the ratio of peak T to peak C fluorescence intensity, and the fluorescence : absorbance ratio fluorescence parameters also have strong correlations with several of the functional assays, in particular the extinction coefficients, benzo(a)pyrene binding and alumina adsorption, and buffering capacity. In many cases, regression equations with a correlation coefficient >0.9 are obtained, suggesting that dissolved organic matter functional character can be predicted from DOM fluorescence properties. For one site, the relationship between dissolved organic matter source, fluorescence, function and carbon isotopic composition is discussed.

  12. [Sources, Migration and Conversion of Dissolved Alkanes, Dissolved Fatty Acids in a Karst Underground River Water, in Chongqing Area].

    PubMed

    Liang, Zuo-bing; Sun, Yu-chuan; Wang, Zun-bo; Shi, Yang; Jiang, Ze-li; Zhang, Mei; Xie, Zheng-Lan; Liao, Yu

    2015-09-01

    Dissolved alkanes and dissolved fatty acids were collected from Qingmuguan underground river in July, October 2013. By gas chromatography-mass spectrometer (GC-MS), alkanes and fatty acids were quantitatively analyzed. The results showed that average contents of alkanes and fatty acids were 1 354 ng.L-1, 24203 ng.L-1 in July, and 667 ng.L-1, 2526 ng.L-1 in October respectively. With the increasing migration distance of dissolved alkanes and dissolved fatty acids in underground river, their contents decreased. Based on the molecular characteristic indices of alkanes, like CPI, OEP, Paq and R, dissolved alkanes were mainly originated from microorganisms in July, and aquatic plants in October. Saturated straight-chain fatty acid had the highest contents in all samples with the dominant peak in C16:0, combined with the characteristics of carbon peak, algae or bacteria might be the dominant source of dissolved fatty acids. PMID:26717680

  13. Temperature Dependence of Photodegradation of Dissolved Organic Matter to Dissolved Inorganic Carbon and Particulate Organic Carbon

    PubMed Central

    Porcal, Petr; Dillon, Peter J.; Molot, Lewis A.

    2015-01-01

    Photochemical transformation of dissolved organic matter (DOM) has been studied for more than two decades. Usually, laboratory or “in-situ” experiments are used to determine photodegradation variables. A common problem with these experiments is that the photodegradation experiments are done at higher than ambient temperature. Five laboratory experiments were done to determine the effect of temperature on photochemical degradation of DOM. Experimental results showed strong dependence of photodegradation on temperature. Mathematical modeling of processes revealed that two different pathways engaged in photochemical transformation of DOM to dissolved inorganic carbon (DIC) strongly depend on temperature. Direct oxidation of DOM to DIC dominated at low temperatures while conversion of DOM to intermediate particulate organic carbon (POC) prior to oxidation to DIC dominated at high temperatures. It is necessary to consider this strong dependence when the results of laboratory experiments are interpreted in regard to natural processes. Photodegradation experiments done at higher than ambient temperature will necessitate correction of rate constants. PMID:26106898

  14. EFFECTS OF SUNLIGHT ON CARBOXYL CONTENT OF DISSOLVED ORGANIC MATTER IN THE SATILLA RIVER OF GEORGIA, UNITED STATES

    EPA Science Inventory

    A study examined the effect of sunlight-initiated photo-degradation of dissolved organic matter (DOM) on its carboxyl content, and the role of oxygen and iron in this process. Solar-simulated irradiations were performed on 0.2-mm filtered water samples collected from the highly c...

  15. FOREST SOIL RESPONSE TO ACID AND SALT ADDITIONS OF SULFATE III. SOLUBILIZATION AND COMPOSITION OF DISSOLVED ORGANIC CARBON

    EPA Science Inventory

    A year-long experiment, using reconstructed spodosol and intact alfisol soil columns, was conducted to examine the effects of various simulated throughfall solutions on soil C dynamics. oil organic C solubilization, dissolved organic C fractions, and decomposition rates were stud...

  16. Dissolved P in streams in dry years and wet years

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dissolved phosphorus (P) has often been identified as the nutrient of concern in lakes, reservoirs, and streams especially where there is evidence of eutrophication. We analyzed contiguous-spatial and temporal variability of dissolved P [soluble reactive P (SRP)] stream concentrations during times ...

  17. Black Carbon in Estuarine and Coastal Ocean Dissolved Organic Matter

    NASA Technical Reports Server (NTRS)

    Mannino, Antonio; Harvey, H. Rodger

    2003-01-01

    Analysis of high-molecular-weight dissolved organic matter (DOM) from two estuaries in the northwest Atlantic Ocean reveals that black carbon (BC) is a significant component of previously uncharacterized DOM, suggesting that river-estuary systems are important exporters of recalcitrant dissolved organic carbon to the ocean.

  18. Artificial neural network modeling of dissolved oxygen in reservoir.

    PubMed

    Chen, Wei-Bo; Liu, Wen-Cheng

    2014-02-01

    The water quality of reservoirs is one of the key factors in the operation and water quality management of reservoirs. Dissolved oxygen (DO) in water column is essential for microorganisms and a significant indicator of the state of aquatic ecosystems. In this study, two artificial neural network (ANN) models including back propagation neural network (BPNN) and adaptive neural-based fuzzy inference system (ANFIS) approaches and multilinear regression (MLR) model were developed to estimate the DO concentration in the Feitsui Reservoir of northern Taiwan. The input variables of the neural network are determined as water temperature, pH, conductivity, turbidity, suspended solids, total hardness, total alkalinity, and ammonium nitrogen. The performance of the ANN models and MLR model was assessed through the mean absolute error, root mean square error, and correlation coefficient computed from the measured and model-simulated DO values. The results reveal that ANN estimation performances were superior to those of MLR. Comparing to the BPNN and ANFIS models through the performance criteria, the ANFIS model is better than the BPNN model for predicting the DO values. Study results show that the neural network particularly using ANFIS model is able to predict the DO concentrations with reasonable accuracy, suggesting that the neural network is a valuable tool for reservoir management in Taiwan. PMID:24078053

  19. Systemic delivery of artemether by dissolving microneedles.

    PubMed

    Qiu, Yuqin; Li, Chun; Zhang, Suohui; Yang, Guozhong; He, Meilin; Gao, Yunhua

    2016-07-11

    Dissolving microneedles (DMNs) based transdermal delivery is an attractive drug delivery approach with minimal invasion. However, it is still challenging to load poorly water-soluble drugs in DMNs for systemic delivery. The aim of the study was to develop DMNs loaded with artemether (ARM) as a model drug, to enable efficient drug penetration through skin for systemic absorption and distribution. The micro-conduits created by microneedles were imaged by confocal laser scanning microscopy (CLSM), and the insertion depth was suggested to be about 270μm. The maximum amount of ARM delivered into skin was 72.67±2.69% of the initial dose loaded on DMNs preparation. Pharmacokinetics study in rats indicated a dose-dependent profile of plasma ARM concentrations, after ARM-loaded DMNs treatment. In contrast to intramuscular injection, DMNs application resulted in lower peak plasma levels, but higher plasma ARM concentration at 8h after administration. There were no significant difference in area under the curve and bioavailability between DMNs group and intramuscular group (P>0.05). Pharmacodynamics studies performed in collagen-induced arthritis (CIA) rats showed that ARM-loaded DMNs could reverse paw edema, similar to ARM intramuscular injection. In conclusion, developed DMNs provided a potential minimally invasive route for systemic delivery of poorly water-soluble drugs. PMID:27150946

  20. Methanex, Hoechst Celanese dissolve methanol partnership

    SciTech Connect

    Morris, G.D.L.

    1993-03-31

    One of the many joint venture alliances recently announced in the petrochemical sector is ending in divorce. Hoechst Celanese Chemical (Dallas) and Methanex Corp. (Vancouver) are in the process of dissolving the partnership they had formed to restart Hoechst Celanese's methanol plant at Clear Lake, TX. Hoechst Celanese says it is actively seeking replacement partners and has several likely prospects, while Methanex is concentrating on its other ventures. Those include its just-completed acquisition of Fletcher Challenge's (Auckland, NZ) methanol business and a joint venture with American Cyanamid to convert an ammonia plant at Fortier, LA to methanol. Methanex will still be the world's largest producer of methanol. Officially, the negotiations between Methanex and Hoechst Celanese just broke down over the last month or so,' says Steve Yurich, operations manager for the Clear Lake plant. Market sources, however, say that Methanex found itself with too many irons in the fire' and pulled out before it ran into financial or perhaps even antitrust difficulties.

  1. Determination of dissolved aluminum in water samples

    USGS Publications Warehouse

    Afifi, A.A.

    1983-01-01

    A technique has been modified for determination of a wide range of concentrations of dissolved aluminum (Al) in water and has been tested. In this technique, aluminum is complexed with 8-hydroxyquinoline at pH 8.3 to minimize interferences, then extracted with methyl isobutyl ketone (MIBK). The extract is analyzed colorimetrically at 395 nm. This technique is used to analyze two forms of monomeric Al, nonlabile (organic complexes) and labile (free, Al, Al sulfate, fluoride and hydroxide complexes). A detection limit 2 ug/L is possible with 25-ml samples and 10-ml extracts. The detection limit can be decreased by increasing the volume of the sample and (or) decreasing the volume of the methyl isobutyl ketone extract. The analytical uncertainty of this method is approximately + or - 5 percent. The standard addition technique provides a recovery test for this technique and ensures precision in samples of low Al concentrations. The average percentage recovery of the added Al plus the amount originally present was 99 percent. Data obtained from analyses of filtered standard solutions indicated that Al is adsorbed on various types of filters. However, the relationship between Al concentrations and adsorption remains linear. A test on standard solutions also indicated that Al is not adsorbed on nitric acid-washed polyethylene and polypropylene bottle wells. (USGS)

  2. Dissolved oxygen enhancement on the Provo River

    SciTech Connect

    Wahl, T.L.; Young, D.

    1995-12-31

    Dissolved oxygen (DO) enhancement activities have been underway for the past two years on the Provo River downstream of the U.S, Bureau of Reclamation`s Deer Creek Dam and Powerplant. A feasibility test during the summer of 1993 demonstrated that a combination of turbine aeration and weir aeration over the tailrace control gates could economically improve DO concentrations immediately downstream of the powerplant. During the summer of 1994 both aeration methods were implemented for two months during the most severe low-DO period. Biological studies were conducted before and during the aeration effort in an attempt to determine the fishery response to DO improvements. Unfortunately, the effectiveness of turbine aeration was limited by unusual powerplant operations prompted by very dry conditions in central Utah in 1994. Weir aeration was more effective. The response of fish populations to low DO levels varied. Marked fish exhibited movement throughout the study area prior, during, and after low-DO periods. Fish condition did not exhibit downward trends during low-DO periods. However, fish exposed to low DO were lethargic and unable to recover from handling stress. Invertebrate populations were dominated by four taxa tolerant to adverse water quality.

  3. [Effect of dissolved oxygen on mutanolysin fermentation].

    PubMed

    Liu, T J; Xu, W L; Sun, W B; Zhang, Y Z

    2000-03-01

    Effects of several parameters relating to dissolved oxygen(DO) on mutanolysin fermentation were studied. The experiment using shake flasks shows that the medium volume and shaker agitation speed affect the production of mutanolysin. At the same time, the agitation rate together with aeation rate has effects on DO in fermentor. Mutanolysin fermentation was affected by DO greatly. Oxygen is a key restricted factor in mutanolysin fermentation. It affects the metablism and physiological action of Streptomyces globisporus S186. Whatever the DO is excessive high or low, it won't benefit the mutanolysin production. If DO is super, S. globisporus S186 will grow luxuriantly but do not produce mutanolysin, while if DO is lower, the S. globisporus S186 won't grow well even not to produce mutanolysin. During the course of fermentation, the DO changed regularly. It is similar to many antibiotic fermentation and some amino acid fermentation. As S. globisporus S186 grow in exponential phase, DO begin to decrease rapidly from 6 h and get to the lowest point at 40 h or so. Subsequently mutanolysin starts to be produced. DO rises again from 90 h. The key technoloyg of oxygen control in the fermentation is to keep the DO at a suboptimum level. In order to get a high mutanolysin yield, during the culture in fermentor the agitation rate and aeration rate should be kept at 200 r/min and 1:0.8(V:V) respectively. PMID:10976334

  4. Composition of dissolved organic matter in groundwater

    NASA Astrophysics Data System (ADS)

    Longnecker, Krista; Kujawinski, Elizabeth B.

    2011-05-01

    Groundwater constitutes a globally important source of freshwater for drinking water and other agricultural and industrial purposes, and is a prominent source of freshwater flowing into the coastal ocean. Therefore, understanding the chemical components of groundwater is relevant to both coastal and inland communities. We used electrospray ionization coupled with Fourier-transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS) to examine dissolved organic compounds in groundwater prior to and after passage through a sediment-filled column containing microorganisms. The data revealed that an unexpectedly high proportion of organic compounds contained nitrogen and sulfur, possibly due to transport of surface waters from septic systems and rain events. We matched 292 chemical features, based on measured mass:charge ( m/z) values, to compounds stored in the Kyoto Encyclopedia of Genes and Genomes (KEGG). A subset of these compounds (88) had only one structural isomer in KEGG, thus supporting tentative identification. Most identified elemental formulas were linked with metabolic pathways that produce polyketides or with secondary metabolites produced by plants. The presence of polyketides in groundwater is notable because of their anti-bacterial and anti-cancer properties. However, their relative abundance must be quantified with appropriate analyses to assess any implications for public health.

  5. Corrosion of irradiated MOX fuel in presence of dissolved H 2

    NASA Astrophysics Data System (ADS)

    Carbol, P.; Fors, P.; Van Winckel, S.; Spahiu, K.

    2009-07-01

    The corrosion behaviour of irradiated MOX fuel (47 GWd/tHM) has been studied in an autoclave experiment simulating repository conditions. Fuel fragments were corroded at room temperature in a 10 mM NaCl/2 mM NaHCO 3 solution in presence of dissolved H 2 for 2100 days. The results show that dissolved H 2 in concentration 1 mM and higher inhibits oxidation and dissolution of the fragments. Stable U and Pu concentrations were measured at 7 × 10 -10 and 5 × 10 -11 M, respectively. Caesium was only released during the first two years of the experiment. The results indicate that the UO 2 matrix of a spent MOX fuel is the main contributor to the measured dissolution, while the corrosion of the high burn-up Pu-rich islands appears negligible.

  6. Evaluation of filter media for clarification of partially dissolved residues containing plutonium

    SciTech Connect

    Foley, E.S.

    1989-10-09

    A common process in the chemical industry employs the leaching of a desirable component from an insoluble substrate, followed by filtration to produce a clarified solution of the desirable component and a discardable residue. The work described here involved evaluating sintered metal filter media for separating dissolved plutonium from undissolved residues generated at various locations owned by the Department of Energy throughout the United States. The work was performed during a six-week assignment at the Savannah River Laboratory as part of a high school science enrichment program conducted in the summer of 1989. The leach step used included dissolving the plutonium-containing solids in a solution of nitric-hydrofluoric acid. To simulate the partial solubility of the actual plutonium-containing residues, a non-radioactive power plant flyash was used. 6 refs., 14 figs., 1 tab.

  7. Dissolved Gas-in-Oil Analysis in Transformers Based on Near-Infrared Photoacoustic Spectroscopy

    NASA Astrophysics Data System (ADS)

    Mao, Xuefeng; Zhou, Xinlei; Zhai, Liang; Yu, Qingxu

    2015-06-01

    This paper investigates an application of near-infrared photoacoustic spectroscopy (PAS) to analyze the dissolved gas-in-oil of a transformer. A near-infrared tunable fiber laser-based PAS system has been developed. Using this system, the gas detection limits (signal-to-noise ratio = 1) of 4 ppb at 1531.59 nm for , 39 ppm at 1565.98 nm for CO, and 34 ppm at 1572.34 are reached. In addition, the fault gas () is produced by a transformer spatial discharge simulation system, and the productivity of the gas is measured quantitatively. The experiment demonstrates the near-infrared PAS system is able to be applied to the dissolved gas analysis of a transformer.

  8. Evaluation of disintegration testing of different fast dissolving tablets using the texture analyzer.

    PubMed

    el-Arini, Silvia Kocova; Clas, Sophie-Dorothée

    2002-01-01

    The in vitro disintegration behavior of fast dissolving systems manufactured by the main commercialized technologies was studied using the texture analyzer (TA) instrument. Quantitative parameters were employed to characterize the effect of the major test variables on the disintegration profiles. The average disintegration profiles of the products were compared using the test conditions that minimized these effects and at the same time mimicked the in vivo situation in the patient's mouth. The differences in the disintegration mechanisms of the fast dissolving systems were reflected in the shape of their disintegration profiles and in the parameters derived from the profiles. The differences were explained in relation to the technology and/or formulation characteristics involved in the manufacture of each product. The in vitro disintegration times obtained under the simulated in vivo conditions were correlated with the reported in vivo disintegration times. PMID:12229267

  9. Bioavailability and characterization of dissolved organic nitrogen and dissolved organic phosphorus in wastewater effluents.

    PubMed

    Qin, Chao; Liu, Haizhou; Liu, Lei; Smith, Scott; Sedlak, David L; Gu, April Z

    2015-04-01

    There is still a great knowledge gap in the understanding of characteristics and bioavailability of dissolved organic nitrogen (DON) and dissolved organic phosphorus (DOP) in wastewater effluents, which surmise implications related to both discharge regulation and treatment practice. In this study, we simultaneously investigated the characteristics and bioavailability of both DON and DOP, with separated hydrophilic versus hydrophobic fractions, in highly-treated wastewater effluents for the first time. The tertiary effluents from two wastewater treatment plants were separated into two fractions by XAD-8 resin coupled with anion exchange resin based on the hydrophobicity. Results showed that the majority of DON was present in hydrophilic forms while more DOP existed in hydrophobic forms. Hydrophilic DON contributed to 64.0%-72.2% of whole DON, while hydrophobic DOP accounted for 61.4%-80.7% of total DOP for the two plants evaluated. The effluents and their fractions were then subject to bioavailability assay based on 14-day algae growth. The results indicated that majority (~73-75%) of the effluent DOP, particularly the hydrophobic fraction with lower C/P ratio was more likely to be bioavailable for algal growth. The bioavailable fraction of DON varied widely (28%-61%) for the two plants studied and the hydrophilic fraction with lower C/N ratio seemed to exhibit higher bioavailability than the hydrophobic portion. The differences in bioavailable DON and DOP distributions of effluents from those two plants could be attributed to different receiving effluent compositions and wastewater treatment processes. In addition, fluorescence excitation-emission matrices (EEMs) combined with parallel factor analysis (PARAFAC) were used to characterize the dissolved organic matter (DOM) in wastewater effluent, which provided insights into the nature of organic matter in wastewater samples with different characteristics and originating sources. PMID:25527968

  10. Dissolved organic carbon and chromophoric dissolved organic matter properties of rivers in the USA

    USGS Publications Warehouse

    Spencer, Robert G.M.; Butler, Kenna D.; Aiken, George R.

    2012-01-01

    Dissolved organic carbon (DOC) concentration and chromophoric dissolved organic matter (CDOM) parameters were measured over a range of discharge in 30 U.S. rivers, covering a diverse assortment of fluvial ecosystems in terms of watershed size and landscape drained. Relationships between CDOM absorption at a range of wavelengths (a254, a350, a440) and DOC in the 30 watersheds were found to correlate strongly and positively for the majority of U.S. rivers. However, four rivers (Colorado, Colombia, Rio Grande and St. Lawrence) exhibited statistically weak relationships between CDOM absorption and DOC. These four rivers are atypical, as they either drain from the Great Lakes or experience significant impoundment of water within their watersheds, and they exhibited values for dissolved organic matter (DOM) parameters indicative of autochthonous or anthropogenic sources or photochemically degraded allochthonous DOM and thus a decoupling between CDOM and DOC. CDOM quality parameters in the 30 rivers were found to be strongly correlated to DOM compositional metrics derived via XAD fractionation, highlighting the potential for examining DOM biochemical quality from CDOM measurements. This study establishes the ability to derive DOC concentration from CDOM absorption for the majority of U.S. rivers, describes characteristics of riverine systems where such an approach is not valid, and emphasizes the possibility of examining DOM composition and thus biogeochemical function via CDOM parameters. Therefore, the usefulness of CDOM measurements, both laboratory-based analyses and in situ instrumentation, for improving spatial and temporal resolution of DOC fluxes and DOM dynamics in future studies is considerable in a range of biogeochemical studies.

  11. Dissolved organic carbon and chromophoric dissolved organic matter properties of rivers in the USA

    NASA Astrophysics Data System (ADS)

    Spencer, Robert G. M.; Butler, Kenna D.; Aiken, George R.

    2012-09-01

    Dissolved organic carbon (DOC) concentration and chromophoric dissolved organic matter (CDOM) parameters were measured over a range of discharge in 30 U.S. rivers, covering a diverse assortment of fluvial ecosystems in terms of watershed size and landscape drained. Relationships between CDOM absorption at a range of wavelengths (a254, a350, a440) and DOC in the 30 watersheds were found to correlate strongly and positively for the majority of U.S. rivers. However, four rivers (Colorado, Colombia, Rio Grande and St. Lawrence) exhibited statistically weak relationships between CDOM absorption and DOC. These four rivers are atypical, as they either drain from the Great Lakes or experience significant impoundment of water within their watersheds, and they exhibited values for dissolved organic matter (DOM) parameters indicative of autochthonous or anthropogenic sources or photochemically degraded allochthonous DOM and thus a decoupling between CDOM and DOC. CDOM quality parameters in the 30 rivers were found to be strongly correlated to DOM compositional metrics derived via XAD fractionation, highlighting the potential for examining DOM biochemical quality from CDOM measurements. This study establishes the ability to derive DOC concentration from CDOM absorption for the majority of U.S. rivers, describes characteristics of riverine systems where such an approach is not valid, and emphasizes the possibility of examining DOM composition and thus biogeochemical function via CDOM parameters. Therefore, the usefulness of CDOM measurements, both laboratory-based analyses and in situ instrumentation, for improving spatial and temporal resolution of DOC fluxes and DOM dynamics in future studies is considerable in a range of biogeochemical studies.

  12. Treatment of trichloroethene and hexavalent chromium by granular iron in the presence of dissolved CaCO3

    NASA Astrophysics Data System (ADS)

    Jeen, Sung-Wook; Yang, YanQi; Gui, Lai; Gillham, Robert W.

    2013-01-01

    Column experiments and numerical simulations were conducted to evaluate the effects of Cr(VI) and dissolved CaCO3 on the iron reactivity towards trichloroethene (TCE) and Cr(VI) reduction. Column experiments included measurements of iron corrosion potential and characterization of surface film composition using Raman spectroscopy. Three columns received different combinations of TCE (5 mg L- 1), Cr(VI) (10 mg L- 1) and dissolved CaCO3 (300 mg L- 1), after short periods of conditioning with Millipore water followed by 10 mg L- 1 TCE in Millipore water, for a total of 8 months. The results showed that co-existence with TCE did not affect Cr(VI) reduction kinetics, however, the presence of Cr(VI) reduced TCE degradation rates significantly. The formation of Fe(III)/Cr(III) products caused progressive passivation of the iron and was consistent with the increase in corrosion potential. The presence of dissolved CaCO3 resulted in a stable corrosion potential and faster degradation rates of TCE and Cr(VI). Over time, however, the accumulation of secondary carbonate minerals on the iron surface decreased the iron reactivity. Numerical simulation using a reactive transport model reproduced the observations from the column experiments reasonably well. The simulation can be valuable in the design of PRBs or in the development of effective maintenance procedures for PRBs treating groundwater co-contaminated with Cr(VI) and TCE in the presence of dissolved CaCO3.

  13. Treatment of trichloroethene and hexavalent chromium by granular iron in the presence of dissolved CaCO3.

    PubMed

    Jeen, Sung-Wook; Yang, YanQi; Gui, Lai; Gillham, Robert W

    2013-01-01

    Column experiments and numerical simulations were conducted to evaluate the effects of Cr(VI) and dissolved CaCO(3) on the iron reactivity towards trichloroethene (TCE) and Cr(VI) reduction. Column experiments included measurements of iron corrosion potential and characterization of surface film composition using Raman spectroscopy. Three columns received different combinations of TCE (5 mg L(-1)), Cr(VI) (10 mg L(-1)) and dissolved CaCO(3) (300 mg L(-1)), after short periods of conditioning with Millipore water followed by 10 mg L(-1) TCE in Millipore water, for a total of 8 months. The results showed that co-existence with TCE did not affect Cr(VI) reduction kinetics, however, the presence of Cr(VI) reduced TCE degradation rates significantly. The formation of Fe(III)/Cr(III) products caused progressive passivation of the iron and was consistent with the increase in corrosion potential. The presence of dissolved CaCO(3) resulted in a stable corrosion potential and faster degradation rates of TCE and Cr(VI). Over time, however, the accumulation of secondary carbonate minerals on the iron surface decreased the iron reactivity. Numerical simulation using a reactive transport model reproduced the observations from the column experiments reasonably well. The simulation can be valuable in the design of PRBs or in the development of effective maintenance procedures for PRBs treating groundwater co-contaminated with Cr(VI) and TCE in the presence of dissolved CaCO(3). PMID:23247400

  14. Scavenging dissolved oxygen via acoustic droplet vaporization.

    PubMed

    Radhakrishnan, Kirthi; Holland, Christy K; Haworth, Kevin J

    2016-07-01

    Acoustic droplet vaporization (ADV) of perfluorocarbon emulsions has been explored for diagnostic and therapeutic applications. Previous studies have demonstrated that vaporization of a liquid droplet results in a gas microbubble with a diameter 5-6 times larger than the initial droplet diameter. The expansion factor can increase to a factor of 10 in gassy fluids as a result of air diffusing from the surrounding fluid into the microbubble. This study investigates the potential of this process to serve as an ultrasound-mediated gas scavenging technology. Perfluoropentane droplets diluted in phosphate-buffered saline (PBS) were insonified by a 2 MHz transducer at peak rarefactional pressures lower than and greater than the ADV pressure amplitude threshold in an in vitro flow phantom. The change in dissolved oxygen (DO) of the PBS before and after ADV was measured. A numerical model of gas scavenging, based on conservation of mass and equal partial pressures of gases at equilibrium, was developed. At insonation pressures exceeding the ADV threshold, the DO of air-saturated PBS decreased with increasing insonation pressures, dropping as low as 25% of air saturation within 20s. The decrease in DO of the PBS during ADV was dependent on the volumetric size distribution of the droplets and the fraction of droplets transitioned during ultrasound exposure. Numerically predicted changes in DO from the model agreed with the experimentally measured DO, indicating that concentration gradients can explain this phenomenon. Using computationally modified droplet size distributions that would be suitable for in vivo applications, the DO of the PBS was found to decrease with increasing concentrations. This study demonstrates that ADV can significantly decrease the DO in an aqueous fluid, which may have direct therapeutic applications and should be considered for ADV-based diagnostic or therapeutic applications. PMID:26964964

  15. Dissolved oxygen as an indicator of bioavailable dissolved organic carbon in groundwater

    USGS Publications Warehouse

    Chapelle, Francis H.; Bradley, Paul M.; McMahon, Peter B.; Kaiser, Karl; Benner, Ron

    2012-01-01

    Concentrations of dissolved oxygen (DO) plotted vs. dissolved organic carbon (DOC) in groundwater samples taken from a coastal plain aquifer of South Carolina (SC) showed a statistically significant hyperbolic relationship. In contrast, DO-DOC plots of groundwater samples taken from the eastern San Joaquin Valley of California (CA) showed a random scatter. It was hypothesized that differences in the bioavailability of naturally occurring DOC might contribute to these observations. This hypothesis was examined by comparing nine different biochemical indicators of DOC bioavailability in groundwater sampled from these two systems. Concentrations of DOC, total hydrolysable neutral sugars (THNS), total hydrolysable amino acids (THAA), mole% glycine of THAA, initial bacterial cell counts, bacterial growth rates, and carbon dioxide production/consumption were greater in SC samples relative to CA samples. In contrast, the mole% glucose of THNS and the aromaticity (SUVA254) of DOC was greater in CA samples. Each of these indicator parameters were observed to change with depth in the SC system in a manner consistent with active biodegradation. These results are uniformly consistent with the hypothesis that the bioavailability of DOC is greater in SC relative to CA groundwater samples. This, in turn, suggests that the presence/absence of a hyperbolic DO-DOC relationship may be a qualitative indicator of relative DOC bioavailability in groundwater systems.

  16. Chapter A6. Section 6.2. Dissolved Oxygen

    USGS Publications Warehouse

    Revised by Lewis, Michael Edward

    2006-01-01

    Accurate data for the concentration of dissolved oxygen in surface and ground waters are essential for documenting changes in environmental water resources that result from natural phenomena and human activities. Dissolved oxygen is necessary in aquatic systems for the survival and growth of many aquatic organisms and is used as an indicator of the health of surface-water bodies. This section of the National Field Manual (NFM) includes U.S. Geological Survey (USGS) guidance and protocols for four methods to determine dissolved-oxygen concentrations: the amperometric, luminescent-sensor, spectrophotometric, and iodometric (Winkler) methods.

  17. Isolation and chemical characterization of dissolved and colloidal organic matter

    USGS Publications Warehouse

    Aiken, G.; Leenheer, J.

    1993-01-01

    Commonly used techniques for the concentration and isolation of organic matter from water, such as preparative chromatography, ultrafiltration and reverse osmosis, and the methods used to analyze the organic matter obtained by these methods are reviewed. The development of methods to obtain organic matter that is associated with fractions of the dissolved organic carbon other than humic substances, such as organic bases, hydrophilic organic acids and colloidal organic matter are discussed. Methods specifically used to study dissolved organic nitrogen and dissolved organic phosphorous are also discussed. -from Authors

  18. Dissolved gas and isotopic tracers of denitrification

    SciTech Connect

    Singleton, M J; Moran, J E; Esser, B K; McNab, W W; Carle, S F; Cey, B D

    2008-02-28

    We present results from field studies in California (USA) where tritium-helium age dating is used in conjunction with major gases (N{sub 2}, O{sub 2}, CH{sub 4}, CO{sub 2}), noble gases (He, Ne, Ar, Kr, Xe), and stable isotopes ({sup 15}N/{sup 14}N, {sup 18}O/{sup 16}O) in order to document nitrate loading and denitrification associated with confined animal agricultural operations and septic systems. Preliminary results show that in-field extraction of the full suite of dissolved gases will be possible using a new Gas Extraction System under development to augment the current Noble Gas Mass Spectrometry and Membrane Inlet Mass Spectrometry techniques. Ascribing observed groundwater nitrate levels to specific current and past land use practices is often complicated by uncertainty in groundwater age and the degree and locus of dentrification. Groundwater age dating at dairy field sites using the {sup 3}H-{sup 3}He method indicates that the highest nitrate concentrations (150-260 mg/L-NO3) occur in waters with apparent ages of <5 yrs, whereas older waters contain excess N{sub 2} from saturated zone denitrification [1]. At a residential septic system site in Livermore, CA, waters with young apparent ages (<1 yr) proximal to leach line drainage have lower nitrate concentrations and elevated nitrate {delta}{sup 15}N and {delta}{sup 18}O values consistent with denitrification, but little evidence for excess N{sub 2}, indicating that denitrification is occurring in the unsaturated zone. Degassing of groundwater can complicate efforts to calculate travel times [2] and to quantify denitrification. Degassed groundwater underlying dairy operations is formed by two distinct mechanisms: (1) recharge of manure lagoon water affected by biogenic gas ebullition [3] and (2) saturated zone denitrification producing N{sub 2} gas above solubility in groundwater. Gas loss due to both mechanisms is evident in the concentrations of noble gases and major gases in dairy groundwater samples.

  19. DISSOLVED OXYGEN, TEMPERATURE, SURVIVAL OF YOUNG AT FISH SPAWNING SITES

    EPA Science Inventory

    Fluctuations of dissolved oxygen concentrations and water temperatures in their natural spawning sites were measured during embryo through larva stages of northern pike (Esox lucius), and during embryo and sac larva stages of bluegills (Lepomis macrochirus) and pumpkinseeds (Lepo...

  20. The effect of membrane filtration on dissolved trace element concentrations

    USGS Publications Warehouse

    Horowitz, A.J.; Lum, K.R.; Garbarino, J.R.; Hall, G.E.M.; Lemieux, C.; Demas, C.R.

    1996-01-01

    The almost universally accepted operational definition for dissolved constituents is based on processing whole-water samples through a 0.45-??m membrane filter. Results from field and laboratory experiments indicate that a number of factors associated with filtration, other than just pore size (e.g., diameter, manufacturer, volume of sample processed, amount of suspended sediment in the sample), can produce substantial variations in the 'dissolved' concentrations of such elements as Fe, Al, Cu, Zn, Pb, Co, and Ni. These variations result from the inclusion/exclusion of colloidally- associated trace elements. Thus, 'dissolved' concentrations quantitated by analyzing filtrates generated by processing whole-water through similar pore- sized membrane filters may not be equal/comparable. As such, simple filtration through a 0.45-??m membrane filter may no longer represent an acceptable operational definition for dissolved chemical constituents. This conclusion may have important implications for environmental studies and regulatory agencies.

  1. Neptunium estimation in dissolver and high-level-waste solutions

    SciTech Connect

    Pathak, P.N.; Prabhu, D.R.; Kanekar, A.S.; Manchanda, V.K.

    2008-07-01

    This papers deals with the optimization of the experimental conditions for the estimation of {sup 237}Np in spent-fuel dissolver/high-level waste solutions using thenoyltrifluoroacetone as the extractant. (authors)

  2. DISSOLVED AIR FLOTATION TREATMENT OF GULF SHRIMP CANNERY WASTEWATER

    EPA Science Inventory

    This study reports on the operation of a plant scale dissolved air flotation system installed to define and evaluate attainable shrimp cannery wastewater treatment levels. The system was operated in all three modes of DAF pressurization. Destabilizing coagulants investigation inc...

  3. FIELD MEASUREMENT OF DISSOLVED OXYGEN: A COMPARISON OF TECHNIQUES

    EPA Science Inventory

    The measurement and interpretation of geochemical redox parameters are key components of ground water remedial investigations. Dissolved oxygen (DO) is perhaps the most robust geochemical parameter in redox characterization; however, recent work has indicated a need for proper da...

  4. 7 CFR 760.115 - Deceased individuals or dissolved entities.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... now a dissolved general partnership or joint venture, all members of the general partnership or joint venture at the time of dissolution or their duly authorized representatives must sign the application...

  5. 7 CFR 1413.113 - Deceased individuals or dissolved entities.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... a dissolved general partnership or joint venture, all members of the general partnership or joint venture at the time of dissolution or their duly authorized representatives must sign the application...

  6. 7 CFR 760.115 - Deceased individuals or dissolved entities.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... now a dissolved general partnership or joint venture, all members of the general partnership or joint venture at the time of dissolution or their duly authorized representatives must sign the application...

  7. COMPARISON OF METHODS FOR DETERMINATION OF DISSOLVED INORGANIC CARBON

    EPA Science Inventory

    The presentation reviews several approaches for determining dissolved inorganic carbon (DIC) in drinking water. xperimental studies compared the accuracy and precision of DIC determination obtained by either direct analysis using a coulometric titration technique, or by comutatio...

  8. DESIGN PROCEDURES FOR DISSOLVED OXYGEN CONTROL OF ACTIVATED SLUDGE PROCESSES

    EPA Science Inventory

    This report presents design procedures and guidelines for the selection of aeration equipment and dissolved (DO) control systems for activated sludge treatment plants. Aeration methods, equipment and application techniques are examined and selection procedures offered. Various DO...

  9. Utilizing Colored Dissolved Organic Matter to Derive Dissolved Black Carbon Export by Arctic Rivers

    NASA Astrophysics Data System (ADS)

    Stubbins, Aron; Spencer, Robert; Mann, Paul; Holmes, R.; McClelland, James; Niggemann, Jutta; Dittmar, Thorsten

    2015-10-01

    Wildfires have produced black carbon (BC) since land plants emerged. Condensed aromatic compounds, a form of BC, have accumulated to become a major component of the soil carbon pool. Condensed aromatics leach from soils into rivers, where they are termed dissolved black carbon (DBC). The transport of DBC by rivers to the sea is a major term in the global carbon and BC cycles. To estimate Arctic river DBC export, 25 samples collected from the six largest Arctic rivers (Kolyma, Lena, Mackenzie, Ob’, Yenisey and Yukon) were analyzed for dissolved organic carbon (DOC), colored dissolved organic matter (CDOM), and DBC. A simple, linear regression between DOC and DBC indicated that DBC accounted for 8.9 ± 0.3% DOC exported by Arctic rivers. To improve upon this estimate, an optical proxy for DBC was developed based upon the linear correlation between DBC concentrations and CDOM light absorption coefficients at 254 nm (a254). Relatively easy to measure a254 values were determined for 410 Arctic river samples between 2004 and 2010. Each of these a254 values was converted to a DBC concentration based upon the linear correlation, providing an extended record of DBC concentration. The extended DBC record was coupled with daily discharge data from the six rivers to estimate riverine DBC loads using the LOADEST modeling program. The six rivers studied cover 53% of the pan-Arctic watershed and exported 1.5 ± 0.1 million tons of DBC per year. Scaling up to the full area of the pan-Arctic watershed, we estimate that Arctic rivers carry 2.8 ± 0.3 million tons of DBC from land to the Arctic Ocean each year. This equates to ~8% of Arctic river DOC export, slightly less than indicated by the simpler DBC vs DOC correlation-based estimate. Riverine discharge is predicted to increase in a warmer Arctic. DBC export was positively correlated with river runoff, suggesting that the export of soil BC to the Arctic Ocean is likely to increase as the Arctic warms.

  10. Cellular partitioning of nanoparticulate versus dissolved metals in marine phytoplankton.

    PubMed

    Bielmyer-Fraser, Gretchen K; Jarvis, Tayler A; Lenihan, Hunter S; Miller, Robert J

    2014-11-18

    Discharges of metal oxide nanoparticles into aquatic environments are increasing with their use in society, thereby increasing exposure risk for aquatic organisms. Separating the impacts of nanoparticle from dissolved metal pollution is critical for assessing the environmental risks of the rapidly growing nanomaterial industry, especially in terms of ecosystem effects. Metal oxides negatively affect several species of marine phytoplankton, which are responsible for most marine primary production. Whether such toxicity is generally due to nanoparticles or exposure to dissolved metals liberated from particles is uncertain. The type and severity of toxicity depends in part on whether phytoplankton cells take up and accumulate primarily nanoparticles or dissolved metal ions. We compared the responses of the marine diatom, Thalassiosira weissflogii, exposed to ZnO, AgO, and CuO nanoparticles with the responses of T. weissflogii cells exposed to the dissolved metals ZnCl2, AgNO3, and CuCl2 for 7 d. Cellular metal accumulation, metal distribution, and algal population growth were measured to elucidate differences in exposure to the different forms of metal. Concentration-dependent metal accumulation and reduced population growth were observed in T. weissflogii exposed to nanometal oxides, as well as dissolved metals. Significant effects on population growth were observed at the lowest concentrations tested for all metals, with similar toxicity for both dissolved and nanoparticulate metals. Cellular metal distribution, however, markedly differed between T. weissflogii exposed to nanometal oxides versus those exposed to dissolved metals. Metal concentrations were highest in the algal cell wall when cells were exposed to metal oxide nanoparticles, whereas algae exposed to dissolved metals had higher proportions of metal in the organelle and endoplasmic reticulum fractions. These results have implications for marine plankton communities as well as higher trophic levels, since

  11. Spatial distribution of dissolved constituents in Icelandic river waters

    NASA Astrophysics Data System (ADS)

    Oskarsdottir, Sigrídur Magnea; Gislason, Sigurdur Reynir; Snorrason, Arni; Halldorsdottir, Stefanía Gudrún; Gisladottir, Gudrún

    2011-02-01

    SummaryIn this study we map the spatial distribution of selected dissolved constituents in Icelandic river waters using GIS methods to study and interpret the connection between river chemistry, bedrock, hydrology, vegetation and aquatic ecology. Five parameters were selected: alkalinity, SiO 2, Mo, F and the dissolved inorganic nitrogen and dissolved inorganic phosphorus mole ratio (DIN/DIP). The highest concentrations were found in rivers draining young rocks within the volcanic rift zone and especially those draining active central volcanoes. However, several catchments on the margins of the rift zone also had high values for these parameters, due to geothermal influence or wetlands within their catchment area. The DIN/DIP mole ratio was higher than 16 in rivers draining old rocks, but lowest in rivers within the volcanic rift zone. Thus primary production in the rivers is limited by fixed dissolved nitrogen within the rift zone, but dissolved phosphorus in the old Tertiary catchments. Nitrogen fixation within the rift zone can be enhanced by high dissolved molybdenum concentrations in the vicinity of volcanoes. The river catchments in this study were subdivided into several hydrological categories. Importantly, the variation in the hydrology of the catchments cannot alone explain the variation in dissolved constituents. The presence or absence of central volcanoes, young reactive rocks, geothermal systems and wetlands is important for the chemistry of the river waters. We used too many categories within several of the river catchments to be able to determine a statistically significant connection between the chemistry of the river waters and the hydrological categories. More data are needed from rivers draining one single hydrological category. The spatial dissolved constituent distribution clearly revealed the difference between the two extremes, the young rocks of the volcanic rift zone and the old Tertiary terrain.

  12. High-pressure injection of dissolved oxygen for hydrocarbon remediation in a fractured dolostone aquifer.

    PubMed

    Greer, K D; Molson, J W; Barker, J F; Thomson, N R; Donaldson, C R

    2010-10-21

    A field experiment was completed at a fractured dolomite aquifer in southwestern Ontario, Canada, to assess the delivery of supersaturated dissolved oxygen (supersaturated with respect to ambient conditions) for enhanced bioremediation of petroleum hydrocarbons in groundwater. The injection lasted for 1.5h using iTi's gPro® oxygen injection technology at pressures of up to 450 kPa and at concentrations of up to 34 mg O₂/L. A three-dimensional numerical model for advective-dispersive transport of dissolved oxygen within a discretely-fractured porous medium was calibrated to the observed field conditions under a conservative (no-consumption) scenario. The simulation demonstrated that oxygen rapidly filled the local intersecting fractures as well as the porous matrix surrounding the injection well. Following injection, the local fractures were rapidly flushed by the natural groundwater flow system but slow back-diffusion ensured a relatively longer residence time in the matrix. A sensitivity analysis showed significant changes in behaviour with varying fracture apertures and hydraulic gradients. Applying the calibrated model to a 7-day continuous injection scenario showed oxygen residence times (at the 3mg/L limit), within a radius of 2-4m from the injection well, of up to 100 days. This study has demonstrated that supersaturated dissolved oxygen can be effectively delivered to this type of a fractured and porous bedrock system at concentrations and residence times potentially sufficient for enhanced aerobic biodegradation. PMID:20727615

  13. Cellulase activity and dissolved organic carbon release from lignocellulose macrophyte-derived in four trophic conditions.

    PubMed

    Bottino, Flávia; Cunha-Santino, Marcela Bianchessi; Bianchini, Irineu

    2016-01-01

    Considering the importance of lignocellulose macrophyte-derived for the energy flux in aquatic ecosystems and the nutrient concentrations as a function of force which influences the decomposition process, this study aims to relate the enzymatic activity and lignocellulose hydrolysis in different trophic statuses. Water samples and two macrophyte species were collected from the littoral zone of a subtropical Brazilian Reservoir. A lignocellulosic matrix was obtained using aqueous extraction of dried plant material (≈40°C). Incubations for decomposition of the lignocellulosic matrix were prepared using lignocelluloses, inoculums and filtered water simulating different trophic statuses with the same N:P ratio. The particulate organic carbon and dissolved organic carbon (POC and DOC, respectively) were quantified, the cellulase enzymatic activity was measured by releasing reducing sugars and immobilized carbon was analyzed by filtration. During the cellulose degradation indicated by the cellulase activity, the dissolved organic carbon daily rate and enzyme activity increased. It was related to a fast hydrolysable fraction of cellulose that contributed to short-term carbon immobilization (ca. 10 days). After approximately 20 days, the dissolved organic carbon and enzyme activity were inversely correlated suggesting that the respiration of microorganisms was responsible for carbon mineralization. Cellulose was an important resource in low nutrient conditions (oligotrophic). However, the detritus quality played a major role in the lignocelluloses degradation (i.e., enzyme activity) and carbon release. PMID:26991278

  14. Characterization of a novel dissolved CO2 sensor for utilization in environmental monitoring and aquaculture industry

    NASA Astrophysics Data System (ADS)

    Balogh, K.; Jesus, João. M.; Gouveia, C.; Domingues, Jorge O.; Markovics, A.; Baptista, J. M.; Kovacs, B.; Pereira, Carlos M.; Borges, Maria-Teresa; Jorge, P. A. S.

    2013-11-01

    A novel optical fiber sensor is presented for measuring dissolved CO2 for water quality monitoring applications, where the optical signal is based either on refractive index changes or on color change. The sensing chemistry is based on the acid-basic equilibrium of 4-nitrophenol, that is converted into the anionic form by addition quaternary ammonium hydroxide. The CO2 sensitive layer was characterized and tested by using simple absorbance/reflectance measurement setups where the sensor was connected to a fiber optic CCD spectrometer. A prototype simulating a real shallow raceway aquaculture system was developed and its hydraulic behavior characterized. A commercially available partial-pressure- NDIR sensor was used as a reference for dissolved CO2 tests with the new optical fiber sensor under development. Preliminary tests allowed verifying the suitability of the new optical sensor for accurately tracking the dissolved carbon dioxide concentration in a suitable operation range. Direct comparison of the new sensor and the reference sensor system allowed to demonstrate the suitability of the new technology but also to identify some fragilities there are presently being addressed.

  15. Formulation of rizatriptan benzoate fast dissolving buccal films by emulsion evaporation technique

    PubMed Central

    Vidyadhara, Suryadevara; Sasidhar, Reddyvallam Lankapalli; Balakrishna, Thalamanchi; Vardhan, Malapolu Santha

    2015-01-01

    Aim: The present study deals with the formulation of fast dissolving films of Rizatriptan benzoate that is used for the treatment of Migraine. The concept of fast-dissolving drug delivery emerged from the desire to provide patient with more conventional means of taking their medication. Materials and Methods: In the present research work, various trials were carried out using film forming agents such as maltodextrin, gum karaya and xanthan gum to prepare an ideal film. Emulsion evaporation method was used for the preparation of films. The prepared films were evaluated for weight uniformity, drug content, film thickness, folding endurance, dispersion test and curling. The in vitro dissolution studies were carried out using simulated salivary fluid (pH 6.8 phosphate buffer). Results: About 97% of the drug was found to be released from the film within 10 min that is a desirable character for fast absorption. The drug excipient interaction studies carried out by differential scanning calorimetry analysis and Fourier transform infrared studies revealed that there were no major interactions between the drugs and excipients used for the preparation of films. Conclusion: Fast dissolving films of Rizatriptan benzoate prepared by emulsion evaporation technique were found to be suitable for eliciting better therapeutic effect in the treatment of migraine. PMID:25838995

  16. High-pressure injection of dissolved oxygen for hydrocarbon remediation in a fractured dolostone aquifer

    NASA Astrophysics Data System (ADS)

    Greer, K. D.; Molson, J. W.; Barker, J. F.; Thomson, N. R.; Donaldson, C. R.

    2010-10-01

    A field experiment was completed at a fractured dolomite aquifer in southwestern Ontario, Canada, to assess the delivery of supersaturated dissolved oxygen (supersaturated with respect to ambient conditions) for enhanced bioremediation of petroleum hydrocarbons in groundwater. The injection lasted for 1.5 h using iTi's gPro® oxygen injection technology at pressures of up to 450 kPa and at concentrations of up to 34 mg O 2/L. A three-dimensional numerical model for advective-dispersive transport of dissolved oxygen within a discretely-fractured porous medium was calibrated to the observed field conditions under a conservative (no-consumption) scenario. The simulation demonstrated that oxygen rapidly filled the local intersecting fractures as well as the porous matrix surrounding the injection well. Following injection, the local fractures were rapidly flushed by the natural groundwater flow system but slow back-diffusion ensured a relatively longer residence time in the matrix. A sensitivity analysis showed significant changes in behaviour with varying fracture apertures and hydraulic gradients. Applying the calibrated model to a 7-day continuous injection scenario showed oxygen residence times (at the 3 mg/L limit), within a radius of 2-4 m from the injection well, of up to 100 days. This study has demonstrated that supersaturated dissolved oxygen can be effectively delivered to this type of a fractured and porous bedrock system at concentrations and residence times potentially sufficient for enhanced aerobic biodegradation.

  17. Resolving Coffee Roasting-Degree Phases Based on the Analysis of Volatile Compounds in the Roasting Off-Gas by Photoionization Time-of-Flight Mass Spectrometry (PI-TOFMS) and Statistical Data Analysis: Toward a PI-TOFMS Roasting Model.

    PubMed

    Czech, Hendryk; Schepler, Claudia; Klingbeil, Sophie; Ehlert, Sven; Howell, Jessalin; Zimmermann, Ralf

    2016-06-29

    Coffee beans of two cultivars, Arabica (Mexico) and Robusta (Vietnam), were roasted in a small-scale drum roaster at different temperature profiles. Evolving volatile compounds out of the roasting off-gas were analyzed by photoionization mass spectrometry at four different wavelengths, either with single-photon ionization (SPI) or resonance-enhanced multiphoton ionization (REMPI). The different analyte selectivities at the four wavelengths and their relevance for the examination of the roasting process were discussed. Furthermore, intensities of observed m/z were grouped by non-negative matrix factorization (NMF) to reveal the temporal evolutions of four roasting phases ("evaporation", "early roast", "late roast", and "overroast") from NMF scores and the corresponding molecular composition from the NMF factor loadings, giving chemically sound results concerning the roasting phases. Finally, linear classifiers were constructed from real mass spectra at maximum NMF scores by linear discriminant analysis to obtain quantities which are simple to measure for real-time analysis of the roasting process. PMID:27309797

  18. Characterization of Urban Runoff Pollution between Dissolved and Particulate Phases

    PubMed Central

    Wei, Zhang; Simin, Li; Fengbing, Tang

    2013-01-01

    To develop urban stormwater management effectively, characterization of urban runoff pollution between dissolved and particulate phases was studied by 12 rainfall events monitored for five typical urban catchments. The average event mean concentration (AEMC) of runoff pollutants in different phases was evaluated. The AEMC values of runoff pollutants in different phases from urban roads were higher than the ones from urban roofs. The proportions of total dissolved solids, total dissolved nitrogen, and total dissolved phosphorus in total ones for all the catchments were 26.19%–30.91%, 83.29%–90.51%, and 61.54–68.09%, respectively. During rainfall events, the pollutant concentration at the initial stage of rainfall was high and then sharply decreased to a low value. Affected by catchments characterization and rainfall distribution, the highest concentration of road pollutants might appear in the later period of rainfall. Strong correlations were also found among runoffs pollutants in different phases. Total suspended solid could be considered as a surrogate for particulate matters in both road and roof runoff, while dissolved chemical oxygen demand could be regarded as a surrogate for dissolved matters in roof runoff. PMID:23935444

  19. Characterization of urban runoff pollution between dissolved and particulate phases.

    PubMed

    Wei, Zhang; Simin, Li; Fengbing, Tang

    2013-01-01

    To develop urban stormwater management effectively, characterization of urban runoff pollution between dissolved and particulate phases was studied by 12 rainfall events monitored for five typical urban catchments. The average event mean concentration (AEMC) of runoff pollutants in different phases was evaluated. The AEMC values of runoff pollutants in different phases from urban roads were higher than the ones from urban roofs. The proportions of total dissolved solids, total dissolved nitrogen, and total dissolved phosphorus in total ones for all the catchments were 26.19%-30.91%, 83.29%-90.51%, and 61.54-68.09%, respectively. During rainfall events, the pollutant concentration at the initial stage of rainfall was high and then sharply decreased to a low value. Affected by catchments characterization and rainfall distribution, the highest concentration of road pollutants might appear in the later period of rainfall. Strong correlations were also found among runoffs pollutants in different phases. Total suspended solid could be considered as a surrogate for particulate matters in both road and roof runoff, while dissolved chemical oxygen demand could be regarded as a surrogate for dissolved matters in roof runoff. PMID:23935444

  20. Dissolved Vanillin as Tracer for Estuarine Lignin Conversion

    NASA Astrophysics Data System (ADS)

    Edelkraut, F.

    1996-12-01

    Lignin is produced only by vascular plants and therefore can be used as a tracer for terrestrial organic carbon input to the estuarine and marine environments. Lignin measurements have been done by analyses of the oxidation products such as vanillin or 4-hydroxybenzaldehyde. In the Elbe Estuary, free dissolved vanillin was analysed in order to test whether such measurements yield information on terrestrial carbon inputs into the Estuary and on the vanillin derived from lignin oxidation. In the period 1990-1992, concentrations of dissolved vanillin in the Elbe ranged from 0 to 60 μ g l -1(mean: 8 μg l -1). Higher values were found in areas of increased microbial activity such as the turbidity zone and the river mouth where the water chemistry is influenced by large tidal flats. No correlation was found between dissolved vanillin and suspended matter concentrations, although lignin is normally associated with suspended particulate matter, nor was a covariance seen between dissolved vanillin and the terrestrial carbon inputs into the Estuary. Apparently, biological conversion of lignin was faster than the transport processes, and local sources were more dominant for the vanillin concentration than riverine sources. The dissolved vanillin turnover was fast and, consequently, a significant amount of lignin may be converted within an estuary. In sediments from the Estuary, the concentrations of dissolved vanillin were similar to those found in the water phase and showed no clear vertical profile. The sediment is unlikely to be the source for vanillin.

  1. On the losses of dissolved CO(2) during champagne serving.

    PubMed

    Liger-Belair, Gérard; Bourget, Marielle; Villaume, Sandra; Jeandet, Philippe; Pron, Hervé; Polidori, Guillaume

    2010-08-11

    Pouring champagne into a glass is far from being consequenceless with regard to its dissolved CO(2) concentration. Measurements of losses of dissolved CO(2) during champagne serving were done from a bottled Champagne wine initially holding 11.4 +/- 0.1 g L(-1) of dissolved CO(2). Measurements were done at three champagne temperatures (i.e., 4, 12, and 18 degrees C) and for two different ways of serving (i.e., a champagne-like and a beer-like way of serving). The beer-like way of serving champagne was found to impact its concentration of dissolved CO(2) significantly less. Moreover, the higher the champagne temperature is, the higher its loss of dissolved CO(2) during the pouring process, which finally constitutes the first analytical proof that low temperatures prolong the drink's chill and helps it to retain its effervescence during the pouring process. The diffusion coefficient of CO(2) molecules in champagne and champagne viscosity (both strongly temperature-dependent) are suspected to be the two main parameters responsible for such differences. Besides, a recently developed dynamic-tracking technique using IR thermography was also used in order to visualize the cloud of gaseous CO(2) which flows down from champagne during the pouring process, thus visually confirming the strong influence of champagne temperature on its loss of dissolved CO(2). PMID:20681665

  2. Assessment of water quality and factors affecting dissolved oxygen in the Sangamon River, Decatur to Riverton, Illinois, summer 1982

    USGS Publications Warehouse

    Schmidt, A.R.; Stamer, J.K.

    1987-01-01

    Water quality and processes that affect the dissolved-oxygen concentration in a 45.9 mile reach of the Sangamon River from Decatur to Riverton, Illinois, were determined from data collected during low-flow periods in the summer of 1982. Relations among dissolved oxygen, water discharge, biochemical oxygen demand, ammonia and nitrite plus nitrate concentrations, and photosynthetic-oxygen production were simulated using a one-dimensional, steady-state computer model. Average dissolved oxygen concentrations ranged from 8.0 milligrams per liter at the upstream end of the study reach at Decatur to 5.2 milligrams per liter 12.2 miles downstream. Ammonia concentrations ranged from 45 milligrams per liter at the mouth of Stevens Creek (2.6 miles downstream from Decatur) to 0.03 milligram per liter at the downstream end of the study reach. Un-ionized ammonia concentrations exceeded the maximum concentration specified in the State water quality standard (0.04 milligram per liter) throughout most of the study reach. Model simulations indicated that oxidation of ammonia to form nitrite plus nitrate was the most significant process leading to low dissolved oxygen concentrations in the river. (USGS)

  3. Puget Sound Dissolved Oxygen Modeling Study: Development of an Intermediate-Scale Hydrodynamic Model

    SciTech Connect

    Yang, Zhaoqing; Khangaonkar, Tarang; Labiosa, Rochelle G.; Kim, Taeyun

    2010-11-30

    The Washington State Department of Ecology contracted with Pacific Northwest National Laboratory to develop an intermediate-scale hydrodynamic and water quality model to study dissolved oxygen and nutrient dynamics in Puget Sound and to help define potential Puget Sound-wide nutrient management strategies and decisions. Specifically, the project is expected to help determine 1) if current and potential future nitrogen loadings from point and non-point sources are significantly impairing water quality at a large scale and 2) what level of nutrient reductions are necessary to reduce or dominate human impacts to dissolved oxygen levels in the sensitive areas. In this study, an intermediate-scale hydrodynamic model of Puget Sound was developed to simulate the hydrodynamics of Puget Sound and the Northwest Straits for the year 2006. The model was constructed using the unstructured Finite Volume Coastal Ocean Model. The overall model grid resolution within Puget Sound in its present configuration is about 880 m. The model was driven by tides, river inflows, and meteorological forcing (wind and net heat flux) and simulated tidal circulations, temperature, and salinity distributions in Puget Sound. The model was validated against observed data of water surface elevation, velocity, temperature, and salinity at various stations within the study domain. Model validation indicated that the model simulates tidal elevations and currents in Puget Sound well and reproduces the general patterns of the temperature and salinity distributions.

  4. Photochemical degradation of dissolved organic matter and dissolved lignin phenols from the Congo River

    NASA Astrophysics Data System (ADS)

    Spencer, Robert G. M.; Stubbins, Aron; Hernes, Peter J.; Baker, Andy; Mopper, Kenneth; Aufdenkampe, Anthony K.; Dyda, Rachael Y.; Mwamba, Vincent L.; Mangangu, Arthur M.; Wabakanghanzi, Jose N.; Six, Johan

    2009-09-01

    Photochemical degradation of Congo River dissolved organic matter (DOM) was investigated to examine the fate of terrigenous DOM derived from tropical ecosystems. Tropical riverine DOM receives greater exposure to solar radiation, particularly in large river plumes discharging directly into the open ocean. Initial Congo River DOM exhibited dissolved organic carbon (DOC) concentration and compositional characteristics typical of organic rich blackwater systems. During a 57 day irradiation experiment, Congo River DOM was shown to be highly photoreactive with a decrease in DOC, chromophoric DOM (CDOM), lignin phenol concentrations (Σ8) and carbon-normalized yields (Λ8), equivalent to losses of ˜45, 85-95, >95 and >95% of initial values, respectively, and a +3.1 ‰ enrichment of the δ13C-DOC signature. The loss of Λ8 and enrichment of δ13C-DOC during irradiation was strongly correlated (r = 0.99, p < 0.01) indicating tight coupling between these biomarkers. Furthermore, the loss of CDOM absorbance was correlated to the loss of Λ8 (e.g., a355 versus Λ8; r = 0.98, p < 0.01) and δ13C-DOC (e.g., a355 versus δ13C; r = 0.97, p < 0.01), highlighting the potential of CDOM absorbance measurements for delineating the photochemical degradation of lignin and thus terrigenous DOM. It is apparent that these commonly used measurements for examination of terrigenous DOM in the oceans have a higher rate of photochemical decay than the bulk DOC pool. Further process-based studies are required to determine the selective removal rates of these biomarkers for advancement of our understanding of the fate of this material in the ocean.

  5. Laboratory Studies of the Effects of Pressure and Dissolved Gas Supersaturation on Turbine-Passed Fish

    SciTech Connect

    Neitzel, Duane A.

    2009-09-14

    Migratory and resident fish in the Columbia River Basin are exposed to stresses associated with hydroelectric power production, including changes in pressure as they pass through turbines and dissolved gas supersaturation (resulting from the release of water from the spillway). To examine pressure changes as a source of turbine-passage injury and mortality, Pacific Northwest National Laboratory scientists conducted specific tests using a hyperbaric chamber. Tests were designed to simulate Kaplan turbine passage conditions and to quantify the response of fish to rapid pressure changes, with and without the complication of fish being acclimated to gas-supersaturated water.

  6. Exchanges and photo-biogeochemical transformation of dissolved organic compounds in Eastern US tidal marsh ecosystems.

    NASA Astrophysics Data System (ADS)

    Tzortziou, Maria; Neale, Patrick; Megonigal, Patrick; Butterworth, Megan; Jaffe, Rudolf

    2010-05-01

    The role of tidal marshes as sources, sinks and/or transformers of biologically important nutrients, carbon and pollutants has been studied in various marsh-estuarine environments and geomorphological settings. Although there is no consensus on the magnitude and direction of marsh-estuary net (particulate and dissolved) organic fluxes, most previous studies suggest that salt marshes export dissolved organic carbon (DOC) to the surrounding estuarine waters. There has been less attention, however, to the influence of transformations on marsh-exported organic carbon composition or "quality". Yet, carbon composition affects a wide variety of estuarine processes, including microbial respiration and photochemistry. Our objectives in this study were to quantify the photo-reactivity and bio-availability of dissolved organic carbon compounds exported from tidal wetlands of the Chesapeake Bay and determine their effects on the optical properties of colored organic matter (CDOM). We quantified DOC bioavailability with two assays of microbial mineralization: the traditional batch incubation approach in which a suspension of DOM and microbial cells (1 µm filtrate) was incubated in bottles for 7 d, and a continuous-flow bioreactor approach in which DOC (0.2 µm filtrate) was passed through a microbial community that had been pre-established on glass beads from the same source water. Photochemical degradation was measured after a 10h exposure to filtered xenon irradiance simulating midday surface exposure. We measured decreases in CDOM absorption and fluorescence spectra, DOC concentrations, changes in molecular weight distribution, and increases in dissolved inorganic carbon (DIC) and CO2. Results provide important insights on the transformation, fate and cycling of marsh-exported organic compounds, and the role of tidal marsh systems as major regulators of short-scale biological, optical and biogeochemical variability in highly dynamic coastal margins and catchment areas.

  7. Attractive surface force in the presence of dissolved gas: a molecular approach.

    PubMed

    Bratko, Dusan; Luzar, Alenka

    2008-02-19

    Despite widespread evidence of the influence of dissolved air on hydrophobic interaction, the mechanisms of observed effects are still unknown. Although some experiments indicate that adsorbed gases can modify the structure of water next to hydrophobic surfaces, gas effects on measured forces have been observed only at large surface separations. Gas-specific depletion of water at a hydrophobic surface has been detected but was not reproduced in subsequent measurements. We use computer simulations to study short-ranged hydrophobic attraction in the absence and presence of dissolved gas and monitor gas adsorption at molecular resolution inaccessible in experiments. Although we observe a significant accumulation of dissolved gases at hydrophobic surfaces, even in supersaturated gas solutions surface concentrations remain too low to induce any significant change in the local structure of water and short-range surface forces. We present direct calculations of the hydrophobic force between model hydrocarbon plates at separations between 1.5 and 4 nm. Although stronger, the calculated solvation force has a similar decay rate as deduced from recent surface force apparatus measurements at a somewhat lower contact angle. Within the statistical uncertainty, short-range attraction is not affected by the presence of dissolved nitrogen, even in supersaturated solution with a gas fugacity as high as 30 atm. Comparisons of the adsorption behavior of N2, O2, CO2, and Ar reveal similar features in contrast to the peculiar suppression of water depletion reported for an Ar solution in a neutron reflectivity experiment. Our calculations reveal a notable difference between pathways to the capillary evaporation of pure water and gas-phase nucleation in confined supersaturated gas solutions. PMID:17979305

  8. Photochemical Degradation of Persistent Organic Pollutants: A Study of Ice Photochemistry Mediated by Dissolved Organic Matter

    NASA Astrophysics Data System (ADS)

    Bobby, R.; Pagano, L.; Grannas, A. M.

    2012-12-01

    It is well established that ice is a reactive medium in the environment and that active photochemistry occurs in frozen systems. Snow and ice contain a number of absorbing species including nitrate, peroxide and organic matter. Upon irradiation, they can generate a variety of reactive intermediates such as hydroxyl radical and singlet oxygen. It has been shown that dissolved organic matter is a ubiquitous component of snow and ice and plays an important role in overall light absorption properties of the sample. Additionally, the reactive intermediates produced can further react with contaminants present and alter their fate in the environment. Unfortunately, the role of dissolved organic matter in ice photochemistry has received little attention. Here we present results from laboratory-based studies aimed at elucidating the role of dissolved organic matter photochemistry on contaminant degradation in ice. Aqueous samples of our target pollutant, aldrin (20 μg/L), in liquid and frozen phases, were irradiated under Q-Panel 340 lamps to simulate the UV radiation profile of natural sunlight. Results indicated that frozen samples degraded more quickly than liquid samples and that the addition of dissolved organic matter increases the aldrin degradation rate significantly. Both terrestrial (Suwannee River, U.S.) and microbial sources (Pony Lake, Antarctica) of DOM were able to sensitize aldrin loss in ice. Scavengers of singlet oxygen, such as furfuryl alcohol and β-carotene, were also added to DOM solutions. Based on the type of organic matter present, the scavengers had different effects on the photochemical degradation of aldrin. Our results indicate that natural organic matter present in ice is an important component of ice photochemical processes.

  9. Actinide partitioning studies using dihexyl-N,N-diethycarbamolymehtyl phosphonate and dissolved zirconium calcine

    SciTech Connect

    Brewer, K.N.; Herbst, R.S.; Law, J.D.; Garn, T.G.; Tillotson, R.D.; Todd, T.A.

    1996-01-01

    A baseline flowsheet capable of partitioning the transuranic (TRU) elements from dissolved zirconium calcines has been developed. The goal of the TRU partitioning process is to remove the TRUs from solutions of dissolved zirconium calcines to below the 10 CFR 61.55 Class A waste limit of 10 nCi/g. Extraction, scrub, strip, and wash distribution coefficients for several elements, including the actinides, were measured in the laboratory by performing equal volume batch contacts. A solvent containing diheyl-N, N- diethylcarbamoylmethyl phosphonate (CMP), tributylphosphate (TBP), and a branched chain hydrocarbon as the diluent were used to develop this process. A non-radioactive zirconium pilot-plant calcine was spiked with the TRUs, U, Tc, or a radioactive isotope of zirconium to simulate the behavior of these elements in actual dissolved zirconium calcine feed. Distribution coefficient data obtained from laboratory testing were used to recommend: (1) solvent composition, (2) scrub solutions capable of selectively removing extracted zirconium while minimizing actinide recycle, (3) optimized strip solutions which quantitatively recover extracted actinides, and (4) feed adjustments necessary for flowsheet efficiency. Laboratory distribution coefficients were used in conjunction with the Generic TRUEX Model (GTM) to develop and recommend a flowsheet for testing in the 5.5-cm Centrifugal Contractor Mockup. GTM results indicate that the recommended flowsheet should remove the actinides from dissolved zirconium calcine feed to below the Class A waste limit of 10 nCi/g. Less than 0.01 wt% of the extracted zirconium will report to the high- activity waste (HAW) fraction using the 0.05 M H{sub 2}C{sub 2}O{sub 4} in 3.0 M HNO{sub 3} scrub, and greater than 99% of the extracted actinides are recovered with 0.001 M HEDPA.

  10. Evaporation of iodine-containing off-gas scrubber solution

    DOEpatents

    Partridge, J.A.; Bosuego, G.P.

    1980-07-14

    Mercuric nitrate-nitric acid scrub solutions containing radioiodine may be reduced in volume without excessive loss of volatile iodine. The use of concentrated nitric acid during an evaporation process oxidizes the mercury-iodide complex to a less volatile mercuric iodate precipitate.

  11. Graphite fuels combustion off-gas treatment options

    SciTech Connect

    Kirkham, R.J.; Lords, R.E.

    1993-03-01

    Scenarios for burning bulk graphite and for burning crushed fuel particles from graphite spent nuclear fuels have been considered. Particulates can be removed with sintered metal filters. Subsequent cooling would then condense semi-volatile fission products into or onto a particulate. These particulates would be trapped by a second sintered metal filter or downstream packed bed. A packed bed scrub column can be used to eliminate most of the iodine-129 and tritium. A molecular sieve bed is proposed to collect the residual {sup 129}I and other tramp radionuclides downstream (Ruthenium, etc.). Krypton-85 can be recovered, if need be, either by cryogenics or by the KALC process (Krypton Adsorption in Liquid Carbon dioxide). Likewise carbon-14 in the form of carbon dioxide could be collected with a caustic or lime scrub solution and incorporated into a grout. Sulfur dioxide present will be well below regulatory concern level of 4.0 tons per year and most of it would be removed by the scrubber. Carbon monoxide emissions will depend on the choice of burner and start-up conditions. Should the system exceed the regulatory concern level, a catalytic converter in the final packed bed will be provided. Radon and its daughters have sufficiently short half-lives (less than two minutes). If necessary, an additional holdup bed can be added before the final HEPA filters or additional volume can be added to the molecular sieve bed to limit radon emissions. The calculated total effective dose equivalent at the Idaho National Engineering Laboratory boundary from a single release of all the {sup 3}, {sup 14}C, {sup 85}Kr, and {sup 129}I in the total fuel mass if 0.43 mrem/year.

  12. Relative effect of temperature and pH on diel cycling of dissolved trace elements in prickly pear creek, Montana

    USGS Publications Warehouse

    Jones, C.A.; Nimick, D.A.; McCleskey, R.B.

    2004-01-01

    Diel (24 hr) cycles in dissolved metal and As concentrations have been documented in many northern Rocky Mountain streams in the U.S.A. The cause(s) of the cycles are unknown, although temperature- and pH-dependent sorption reactions have been cited as likely causes. A light/dark experiment was conducted to isolate temperature and pH as variables affecting diel metal cycles in Prickly Pear Creek, Montana. Light and dark chambers containing sediment and a strand of macrophyte were placed in the stream to simulate instream temperature oscillations. Photosynthesis-induced pH changes were allowed to proceed in the light chambers while photosynthesis was prevented in the dark chambers. Water samples were collected periodically for 22 hr in late July 2001 from all chambers and the stream. In the stream, dissolved Zn concentrations increased by 300% from late afternoon to early morning, while dissolved As concentrations exhibited the opposite pattern, increasing 33% between early morning and late afternoon. Zn and As concentrations in the light chambers showed similar, though less pronounced, diel variations. Conversely, Zn and As concentrations in the dark chambers had no obvious diel variation, indicating that light, or light-induced reactions, caused the variation. Temperature oscillations were nearly identical between light and dark chambers, strongly suggesting that temperature was not controlling the diel variations. As expected, pH was negatively correlated (P < 0.01) with dissolved Zn concentrations and positively correlated with dissolved As concentrations in both the light and dark chambers. From these experiments, photosynthesis-induced pH changes were determined to be the major cause of the diel dissolved Zn and As cycles in Prickly Pear Creek. Further research is necessary in other streams to verify that this finding is consistent among streams having large differences in trace-element concentrations and mineralogy of channel substrate. ?? 2004 Kluwer

  13. K Basin Sludge Conditioning Process Testing Partitioning of PCBs in Dissolver Solution After Neutralization/Precipitation (Caustic Adjustment)

    SciTech Connect

    Schmidt, A.J.; Thornton, B.M.; Hoppe, E.W.; Mong, G.M.; Silvers, K.L.; Slate, S.O.

    1999-01-04

    The purpose of the work described in this report was to gain a better understanding of how PCB congeners present in a simulated K Basin sludge dissolver solution will partition upon neutralization and precipitation (i.e., caustic adjustment). In a previous study (Mong et al. 1998),the entire series of sludge conditioning steps (acid dissolution, filtration, and caustic adjustment) were examined during integrated testing. In the work described here, the caustic adjustment step was isolated to examine the fate of PCBs in more detail within this processing step. For this testing, solutions of dissolver simulant (containing no solids) with a known initial concentration of PCB congeners were neutralized with caustic to generate a clarified supernatant and a settled sludge phase. PCBs were quantified in each phase (including the PCBs associated with the test vessel rinsates), and material balance information was collected.

  14. Ocean metabolism and dissolved organic matter: How do small dissolved molecules persist in the ocean?

    NASA Astrophysics Data System (ADS)

    Benner, Ronald

    2010-05-01

    The ocean reservoir of dissolved organic matter (DOM) is among the largest global reservoirs (~700 Pg C) of reactive organic carbon. Marine primary production (~50 Pg C/yr) by photosynthetic microalgae and cyanobacteria is the major source of organic matter to the ocean and the principal substrate supporting marine food webs. The direct release of DOM from phytoplankton and other organisms as well as a variety of other processes, such as predation and viral lysis, contribute to the ocean DOM reservoir. Continental runoff and atmospheric deposition are relatively minor sources of DOM to the ocean, but some components of this material appear to be resistant to decomposition and to have a long residence time in the ocean. Concentrations of DOM are highest in surface waters and decrease with depth, a pattern that reflects the sources and diagenesis of DOM in the upper ocean. Most (70-80%) marine DOM exists as small molecules of low molecular weight (<1 kDalton). Surprisingly, high-molecular-weight (>1 kDalton) DOM is relatively enriched in major biochemicals, such as combined neutral sugars and amino acids, and is more bioavailable than low-molecular-weight DOM. The observed relationships among the size, composition, and reactivity of DOM have led to the size-reactivity continuum model, which postulates that diagenetic processes lead to the production of smaller molecules that are structurally altered and resistant to microbial degradation. The radiocarbon content of these small dissolved molecules also indicates these are the most highly aged components of DOM. Chemical signatures of bacteria are abundant in DOM and increase during diagenesis, indicating bacteria are an important source of slowly cycling biochemicals. Recent analyses of DOM isolates by ultrahigh-resolution mass spectrometry have revealed an incredibly diverse mixture of molecules. Carboxyl-rich alicyclic molecules are abundant in DOM, and they appear to be derived from diagenetically

  15. Variable C : N : P stoichiometry of dissolved organic matter cycling in the Community Earth System Model

    DOE PAGESBeta

    Letscher, R. T.; Moore, J. K.; Teng, Y. -C.; Primeau, F.

    2015-01-12

    Dissolved organic matter (DOM) plays an important role in the ocean's biological carbon pump by providing an advective/mixing pathway for ~ 20% of export production. DOM is known to have a stoichiometry depleted in nitrogen (N) and phosphorus (P) compared to the particulate organic matter pool, a fact that is often omitted from biogeochemical ocean general circulation models. However the variable C : N : P stoichiometry of DOM becomes important when quantifying carbon export from the upper ocean and linking the nutrient cycles of N and P with that of carbon. Here we utilize recent advances in DOM observationalmore » data coverage and offline tracer-modeling techniques to objectively constrain the variable production and remineralization rates of the DOM C : N : P pools in a simple biogeochemical-ocean model of DOM cycling. The optimized DOM cycling parameters are then incorporated within the Biogeochemical Elemental Cycling (BEC) component of the Community Earth System Model (CESM) and validated against the compilation of marine DOM observations. The optimized BEC simulation including variable DOM C : N : P cycling was found to better reproduce the observed DOM spatial gradients than simulations that used the canonical Redfield ratio. Global annual average export of dissolved organic C, N, and P below 100 m was found to be 2.28 Pg C yr-1 (143 Tmol C yr-1, 16.4 Tmol N yr-1, and 1 Tmol P yr-1, respectively, with an average export C : N : P stoichiometry of 225 : 19 : 1 for the semilabile (degradable) DOM pool. Dissolved organic carbon (DOC) export contributed ~ 25% of the combined organic C export to depths greater than 100 m.« less

  16. Effect of membrane filtration artifacts on dissolved trace element concentrations

    USGS Publications Warehouse

    Horowitz, Arthur J.; Elrick, Kent A.; Colberg, Mark R.

    1992-01-01

    Among environment scientists, the current and almost universally accepted definition of dissolved constituents is an operational one; only those materials which pass through a 0.45-??m membrane filter are considered to be dissolved. Detailed laboratory and field studies on Fe and Al indicate that a number of factors associated with filtration, other than just pore size, can substantially alter 'dissolved' trace element concentrations; these include: filter type, filter diameter, filtration method, volume of sample processed, suspended sediment concentration, suspended sediment grain-size distribution, concentration of colloids and colloidally associated trace elements and concentration of organic matter. As such, reported filtered-water concentrations employing the same pore size filter may not be equal. Filtration artifacts may lead to the production of chemical data that indicate seasonal or annual 'dissolved' chemical trends which do not reflect actual environmental conditions. Further, the development of worldwide averages for various dissolved chemical constituents, the quantification of geochemical cycles, and the determination of short- or long-term environmental chemical trends may be subject to substantial errors, due to filtration artifacts, when data from the same or multiple sources are combined. Finally, filtration effects could have a substantial impact on various regulatory requirements.

  17. Leaching of dissolved phosphorus from tile-drained agricultural areas.

    PubMed

    Andersen, H E; Windolf, J; Kronvang, B

    2016-01-01

    We investigated leaching of dissolved phosphorus (P) from 45 tile-drains representing animal husbandry farms in all regions of Denmark. Leaching of P via tile-drains exhibits a high degree of spatial heterogeneity with a low concentration in the majority of tile-drains and few tile-drains (15% in our investigation) having high to very high concentration of dissolved P. The share of dissolved organic P (DOP) was high (up to 96%). Leaching of DOP has hitherto been a somewhat overlooked P loss pathway in Danish soils and the mechanisms of mobilization and transport of DOP needs more investigation. We found a high correlation between Olsen-P and water extractable P. Water extractable P is regarded as an indicator of risk of loss of dissolved P. Our findings indicate that Olsen-P, which is measured routinely in Danish agricultural soils, may be a useful proxy for the P leaching potential of soils. However, we found no straight-forward correlation between leaching potential of the top soil layer (expressed as either degree of P saturation, Olsen-P or water extractable P) and the measured concentration of dissolved P in the tile-drain. This underlines that not only the source of P but also the P loss pathway must be taken into account when evaluating the risk of P loss. PMID:27332841

  18. The diffusion of dissolved silica in dilute aqueous solution

    NASA Astrophysics Data System (ADS)

    Applin, Kenneth R.

    1987-08-01

    The diffusion coefficient of dissolved silica at 25.5 ± .5° C was determined as a function of concentration using a non-steady-state method whereby agar-gelled solutions containing dissolved silica from 0.09 to 1.50 mM ( pH = 5.5) were placed in contact with distilled water in glass cells. Diffusion coefficients were obtained by measuring the dissolved silica content of the distilled water after a given length of time. The measured diffusion coefficients decreased as a function of increasing dissolved silica concentration, which is thought to reflect an increase in dimeric silica according to the equilibrium: 2 Si( OH) 4 = Si2O( OH) 6 + H2O. The tracer diffusion coefficients for Si(OH) 4 and Si 2O(OH) 6 and an association constant for the above reaction were determined by fitting the following equation to the experimental data: Dobs = αDmonomer + (1 - α) Ddimer where α is the fraction of total dissolved silica which is Si(OH) 4. The best fit yielded tracer D's for Si(OH) 4 and Si 2O(OH) 6 of 2.2 and 1.0 (in units of 10 -5 cm 2 sec -1), respectively, and an association constant of 330.

  19. Influence of dissolved organic matter on dissolved vanadium speciation in the Churchill River estuary (Manitoba, Canada).

    PubMed

    Shi, Yong Xiang; Mangal, Vaughn; Guéguen, Céline

    2016-07-01

    Diffusive gradients in thin films (DGT) devices were used to investigate the temporal and spatial changes in vanadium (V) speciation in the Churchill estuary system (Manitoba). Thirty-six DGT sets and 95 discrete water samples were collected at 8 river and 3 estuary sites during spring freshet and summer base flow. Dissolved V concentration in the Churchill River at summer base flow was approximately 5 times higher than those during the spring high flow (27.3 ± 18.9 nM vs 4.8 ± 3.5 nM). DGT-labile V showed an opposite trend with greater values found during the spring high flow (2.6 ± 1.8 nM vs 1.4 ± 0.3 nM). Parallel factor analysis (PARAFAC) conducted on 95 excitation-emission matrix spectra validated four humic-like (C1C4) and one protein-like (C5) fluorescent components. Significant positive relationship was found between protein-like DOM and DGT-labile V (r = 0.53, p < 0.05), indicating that protein-like DOM possibly affected the DGT-labile V concentration in Churchill River. Sediment leachates were enriched in DGT-labile V and protein-like DOM, which can be readily released when river sediment began to thaw during spring freshet. PMID:27065459

  20. Removal of dissolved organic matter by anion exchange: Effect of dissolved organic matter properties

    USGS Publications Warehouse

    Boyer, T.H.; Singer, P.C.; Aiken, G.R.

    2008-01-01

    Ten isolates of aquatic dissolved organic matter (DOM) were evaluated to determine the effect that chemical properties of the DOM, such as charge density, aromaticity, and molecular weight, have on DOM removal by anion exchange. The DOM isolates were characterized asterrestrial, microbial, or intermediate humic substances or transphilic acids. All anion exchange experiments were conducted using a magnetic ion exchange (MIEX) resin. The charge density of the DOM isolates, determined by direct potentiometric titration, was fundamental to quantifying the stoichiometry of the anion exchange mechanism. The results clearly show that all DOM isolates were removed by anion exchange; however, differences among the DOM isolates did influence their removal by MIEX resin. In particular, MIEX resin had the greatest affinity for DOM with high charge density and the least affinity for DOM with low charge density and low aromaticity. This work illustrates that the chemical characteristics of DOM and solution conditions must be considered when evaluating anion exchange treatment for the removal of DOM. ?? 2008 American Chemical Society.

  1. Time Series Stream Temperature And Dissolved Oxygen Modeling In The Lower Flint River Basin

    NASA Astrophysics Data System (ADS)

    Li, G.; Jackson, C. R.

    2004-12-01

    The tributaries of the Lower Flint River Basin (LFRB) are incised into the upper Floridan semi-confined limestone aquifer, and thus seepage of relatively old groundwater sustains baseflows and provides some control over temperature and dissolved oxygen fluctuations. This hydrologic and geologic setting creates aquatic habitat that is unique in the state of Georgia. Groundwater withdrawals and possible water supply reservoirs threaten to exacerbate low flow conditions during summer droughts, which may force negative impacts to stream temperature and dissolved oxygen (DO). To evaluate the possible effects of human modifications to stream habitat, summer time series (in 15 min interval) of stream temperature and DO were monitored over the last three years along these streams, and a Continuously Stirred Tank Reactor (CSTR) model was developed and calibrated with these data. The driving forces of the diel trends and the overall levels of stream temperature and DO were identified by this model. Simulations were conducted with assumed managed flow conditions to illustrate potential effects of various stream flow regimes on stream temperature and DO time series. The goal of this research is to provide an accurate simulation tool to guide management decisions.

  2. Extreme conditions in a dissolving air nanobubble

    NASA Astrophysics Data System (ADS)

    Yasui, Kyuichi; Tuziuti, Toru; Kanematsu, Wataru

    2016-07-01

    Numerical simulations of the dissolution of an air nanobubble in water have been performed taking into account the effect of bubble dynamics (inertia of the surrounding liquid). The presence of stable bulk nanobubbles is not assumed in the present study because the bubble radius inevitably passes the nanoscale in the complete dissolution of a bubble. The bubble surface is assumed to be clean because attachment of hydrophobic materials on the bubble surface could considerably change the gas diffusion rate. The speed of the bubble collapse (the bubble wall speed) increases to about 90 m/s or less. The shape of a bubble is kept nearly spherical because the amplitude of the nonspherical component of the bubble shape is negligible compared to the instantaneous bubble radius. In other words, a bubble never disintegrates into daughter bubbles during the dissolution. At the final moment of the dissolution, the temperature inside a bubble increases to about 3000 K due to the quasiadiabatic compression. The bubble temperature is higher than 1000 K only for the final 19 ps. However, the Knudsen number is more than 0.2 for this moment, and the error associated with the continuum model should be considerable. In the final 2.3 ns, only nitrogen molecules are present inside a bubble as the solubility of nitrogen is the lowest among the gas species. The radical formation inside a bubble is negligible because the probability of nitrogen dissociation is only on the order of 10-15. The pressure inside a bubble, as well as the liquid pressure at the bubble wall, increases to about 5 GPa at the final moment of dissolution. The pressure is higher than 1 GPa for the final 0.7 ns inside a bubble and for the final 0.6 ns in the liquid at the bubble wall. The liquid temperature at the bubble wall increases to about 360 K from 293 K at the final stage of the complete dissolution.

  3. Extreme conditions in a dissolving air nanobubble.

    PubMed

    Yasui, Kyuichi; Tuziuti, Toru; Kanematsu, Wataru

    2016-07-01

    Numerical simulations of the dissolution of an air nanobubble in water have been performed taking into account the effect of bubble dynamics (inertia of the surrounding liquid). The presence of stable bulk nanobubbles is not assumed in the present study because the bubble radius inevitably passes the nanoscale in the complete dissolution of a bubble. The bubble surface is assumed to be clean because attachment of hydrophobic materials on the bubble surface could considerably change the gas diffusion rate. The speed of the bubble collapse (the bubble wall speed) increases to about 90 m/s or less. The shape of a bubble is kept nearly spherical because the amplitude of the nonspherical component of the bubble shape is negligible compared to the instantaneous bubble radius. In other words, a bubble never disintegrates into daughter bubbles during the dissolution. At the final moment of the dissolution, the temperature inside a bubble increases to about 3000 K due to the quasiadiabatic compression. The bubble temperature is higher than 1000 K only for the final 19 ps. However, the Knudsen number is more than 0.2 for this moment, and the error associated with the continuum model should be considerable. In the final 2.3 ns, only nitrogen molecules are present inside a bubble as the solubility of nitrogen is the lowest among the gas species. The radical formation inside a bubble is negligible because the probability of nitrogen dissociation is only on the order of 10^{-15}. The pressure inside a bubble, as well as the liquid pressure at the bubble wall, increases to about 5 GPa at the final moment of dissolution. The pressure is higher than 1 GPa for the final 0.7 ns inside a bubble and for the final 0.6 ns in the liquid at the bubble wall. The liquid temperature at the bubble wall increases to about 360 K from 293 K at the final stage of the complete dissolution. PMID:27575216

  4. Formulation Development and Evaluation of Fast Dissolving Film of Telmisartan

    PubMed Central

    Londhe, Vaishali Y.; Umalkar, Kashmira B.

    2012-01-01

    Hypertension is a major cause of concern not just in the elderly but also in the youngsters. An effort was made to formulate a fast dissolving film containing telmisartan which is used in the treatment of hypertension with a view to improve the onset of action, therapeutic efficacy, patient compliance and convenience. The major challenge in formulation of oral films of telmisatran is that it shows very less solubility in the pH range of 3–9. Various film forming agents and polyhydric alcohols were evaluated for optimizing composition of fast dissolving films. Fast dissolving films using hydroxypropyl methylcellulose, polyvinyl alcohol, glycerol, sorbitol, menthol and an alkalizer were formulated using solvent casting method. Optimized formulations were evaluated for their weight, thickness, folding endurance, appearance, tensile strength, disintegration time and dissolution profile. PMID:23325992

  5. Formulation development and evaluation of fast dissolving film of telmisartan.

    PubMed

    Londhe, Vaishali Y; Umalkar, Kashmira B

    2012-03-01

    Hypertension is a major cause of concern not just in the elderly but also in the youngsters. An effort was made to formulate a fast dissolving film containing telmisartan which is used in the treatment of hypertension with a view to improve the onset of action, therapeutic efficacy, patient compliance and convenience. The major challenge in formulation of oral films of telmisatran is that it shows very less solubility in the pH range of 3-9. Various film forming agents and polyhydric alcohols were evaluated for optimizing composition of fast dissolving films. Fast dissolving films using hydroxypropyl methylcellulose, polyvinyl alcohol, glycerol, sorbitol, menthol and an alkalizer were formulated using solvent casting method. Optimized formulations were evaluated for their weight, thickness, folding endurance, appearance, tensile strength, disintegration time and dissolution profile. PMID:23325992

  6. Microscopic residues of bone from dissolving human remains in acids.

    PubMed

    Vermeij, Erwin; Zoon, Peter; van Wijk, Mayonne; Gerretsen, Reza

    2015-05-01

    Dissolving bodies is a current method of disposing of human remains and has been practiced throughout the years. During the last decade in the Netherlands, two cases have emerged in which human remains were treated with acid. In the first case, the remains of a cremated body were treated with hydrofluoric acid. In the second case, two complete bodies were dissolved in a mixture of hydrochloric and sulfuric acid. In both cases, a great variety of evidence was collected at the scene of crime, part of which was embedded in resin, polished, and investigated using SEM/EDX. Apart from macroscopic findings like residual bone and artificial teeth, in both cases, distinct microscopic residues of bone were found as follows: (partly) digested bone, thin-walled structures, and recrystallized calcium phosphate. Although some may believe it is possible to dissolve a body in acid completely, at least some of these microscopic residues will always be found. PMID:25677640

  7. Effects of dissolved organic matter from a eutrophic lake on the freely dissolved concentrations of emerging organic contaminants.

    PubMed

    Xiao, Yi-Hua; Huang, Qing-Hui; Vähätalo, Anssi V; Li, Fei-Peng; Chen, Ling

    2014-08-01

    The authors studied the effects of dissolved organic matter (DOM) on the bioavailability of bisphenol A (BPA) and chloramphenicol by measuring the freely dissolved concentrations of the contaminants in solutions containing DOM that had been isolated from a mesocosm in a eutrophic lake. The abundance and aromaticity of the chromophoric DOM increased over the 25-d mesocosm experiment. The BPA freely dissolved concentration was 72.3% lower and the chloramphenicol freely dissolved concentration was 56.2% lower using DOM collected on day 25 than using DOM collected on day 1 of the mesocosm experiment. The freely dissolved concentrations negatively correlated with the ultraviolent absorption coefficient at 254 nm and positively correlated with the spectral slope of chromophoric DOM, suggesting that the bioavailability of these emerging organic contaminants depends on the characteristics of the DOM present. The DOM-water partition coefficients (log KOC ) for the emerging organic contaminants positively correlated with the aromaticity of the DOM, measured as humic acid-like fluorescent components C1 (excitation/emission=250[313]/412 nm) and C2 (excitation/emission=268[379]/456 nm). The authors conclude that the bioavailability of emerging organic contaminants in eutrophic lakes can be affected by changes in the DOM. PMID:24839192

  8. Novel System for Continuous Measurements of Dissolved Gases in Liquids

    NASA Astrophysics Data System (ADS)

    Baer, D. S.; Liem, J.; Owano, T. G.; Gupta, M.

    2014-12-01

    Measurements of dissolved gases in lakes, rivers and oceans may be used to quantify underwater greenhouse gas generation, air-surface exchange, and pollution migration. Studies involving quantification of dissolved gases typically require obtaining water samples (from streams, lakes, or ocean water) and transporting them to a laboratory, where they are degased. The gases obtained are then generally measured using gas chromatography and isotope ratio mass spectrometry for concentrations and isotope ratios, respectively. This conventional, off-line, discrete-sample methodology is time consuming and labor intensive, and thus severely inhibits detailed spatial and temporal mapping of dissolved gases. In this work, we describe the commercial development of a new portable membrane-based gas extraction system (18.75" x 18.88" x 10.69", 16 kg, 85 watts) that interfaces directly to our cavity enhanced laser absorption based (or Off-Axis ICOS) gas analyzers to continuously and quickly measure concentrations and isotope ratios of dissolved gases. By accurately controlling the water flow rate through the membrane contactor, gas pressure on the outside and water pressure on the inside of the membrane, the system can generate precise and highly reproducible results. Furthermore, the gas-phase mole fractions (parts per million, ppm) may be converted into dissolved gas concentrations (nM), by accurately measuring the gas flow rates in and out of the extraction system. We will present detailed laboratory test data that quantifies the performance (linearity, precision, and dynamic range) of the system for measurements of the concentrations and isotope ratios of dissolved greenhouse gases (methane, carbon dioxide, and nitrous oxide) continuously and in real time.

  9. Rapid Dissolving-Debonding Strategy for Optically Transparent Paper Production

    PubMed Central

    Chen, Jinbo; Han, Xiaogang; Fang, Zhiqiang; Cheng, Fan; Zhao, Bin; Lu, Pengbo; Li, Jun; Dai, Jiaqi; Lacey, Steven; Elspas, Raphael; Jiang, Yuhao; Liu, Detao; Hu, Liangbing

    2015-01-01

    Transparent paper is an alternative substrate for electronic devices due to its unique properties. However, energy-intensive and/or time-consuming procedures currently limit the scalable production of transparent paper. In this report, we demonstrate a rapid process to fabricate optically transparent paper with regenerative cellulose fibers (RCFs) by employing a dissolving-debonding strategy. The RCFs have an average width of 19.3 μm and length of several hundred microns and are prepared into transparent paper by vacuum filtration. This new dissolving-debonding approach enables high production efficiency while creating transparent paper with excellent optical and mechanical properties. PMID:26657809

  10. Nano-Enriched and Autonomous Sensing Framework for Dissolved Oxygen.

    PubMed

    Shehata, Nader; Azab, Mohammed; Kandas, Ishac; Meehan, Kathleen

    2015-01-01

    This paper investigates a nano-enhanced wireless sensing framework for dissolved oxygen (DO). The system integrates a nanosensor that employs cerium oxide (ceria) nanoparticles to monitor the concentration of DO in aqueous media via optical fluorescence quenching. We propose a comprehensive sensing framework with the nanosensor equipped with a digital interface where the sensor output is digitized and dispatched wirelessly to a trustworthy data collection and analysis framework for consolidation and information extraction. The proposed system collects and processes the sensor readings to provide clear indications about the current or the anticipated dissolved oxygen levels in the aqueous media. PMID:26287211

  11. Rapid Dissolving-Debonding Strategy for Optically Transparent Paper Production

    NASA Astrophysics Data System (ADS)

    Chen, Jinbo; Han, Xiaogang; Fang, Zhiqiang; Cheng, Fan; Zhao, Bin; Lu, Pengbo; Li, Jun; Dai, Jiaqi; Lacey, Steven; Elspas, Raphael; Jiang, Yuhao; Liu, Detao; Hu, Liangbing

    2015-12-01

    Transparent paper is an alternative substrate for electronic devices due to its unique properties. However, energy-intensive and/or time-consuming procedures currently limit the scalable production of transparent paper. In this report, we demonstrate a rapid process to fabricate optically transparent paper with regenerative cellulose fibers (RCFs) by employing a dissolving-debonding strategy. The RCFs have an average width of 19.3 μm and length of several hundred microns and are prepared into transparent paper by vacuum filtration. This new dissolving-debonding approach enables high production efficiency while creating transparent paper with excellent optical and mechanical properties.

  12. Dissolved-oxygen quenching of in-situ fluorescence measurements

    NASA Astrophysics Data System (ADS)

    Chudyk, Wayne; Tonaszuck, David; Pohlig, Kenneth

    1993-04-01

    In-situ fluorescence measurements of aromatic organic ground water contaminants do not always agree with gas chromatographic methods. Dissolved oxygen quenching of fluorescence may be an interferant in field measurements. Two standard fluorescent aromatics, quinine sulfate and naphthalene, were evaluated in this study. Over the range of dissolved oxygen concentrations expected to be encountered in the field, no effects of oxygen quenching on fluorescence of these compounds was observed. Quenching of quinine sulfate fluorescence by sodium chloride was observed using this system. Sodium chloride quenching was shown to follow the Stern-Volmer relation.

  13. Dissolvable bridges for manipulating fluid volumes in paper networks

    PubMed Central

    Houghtaling, Jared; Liang, Tinny; Thiessen, Gregory; Fu, Elain

    2013-01-01

    A capability that is key to increasing the performance of paper microfluidic devices is control of fluid transport in the devices. We present dissolvable bridges as a novel method of manipulating fluid volumes within paper-based devices. We demonstrate and characterize the operation of the bridges, including tunability of the volumes passed from 10 to 80 μL using parameters such as geometry and composition. We further demonstrate the utility of dissolvable bridges in the important context of automated delivery of different volumes of a fluid from a common source to multiple locations in a device for simple device loading and activation. PMID:24228812

  14. Thermodynamic properties of gases dissolved in electrolyte solutions.

    NASA Technical Reports Server (NTRS)

    Tiepel, E. W.; Gubbins, K. E.

    1973-01-01

    A method based on perturbation theory for mixtures is applied to the prediction of thermodynamic properties of gases dissolved in electrolyte solutions. The theory is compared with experimental data for the dependence of the solute activity coefficient on concentration, temperature, and pressure; calculations are included for partial molal enthalpy and volume of the dissolved gas. The theory is also compared with previous theories for salt effects and found to be superior. The calculations are best for salting-out systems. The qualitative feature of salting-in is predicted by the theory, but quantitative predictions are not satisfactory for such systems; this is attributed to approximations made in evaluating the perturbation terms.

  15. Relationship between ecosystem respiration and aeration constant in open channel dissolved oxygen analysis

    NASA Astrophysics Data System (ADS)

    Parker, S. J.; Butler, A. P.; Heppell, C. M.

    2015-12-01

    Using the open channel diel method of Odum (1956) and the night-time regression method (Hornberger and Kelly, 1985), we analysed a time series of dissolved oxygen (DO) in two slow flowing streams for a two month period in summer 2014 and obtained values for ecosystem respiration and the aeration constant for each day in the period. We then used the standard dissolved oxygen lumped model to generate a DO time series behaviour for one of those rivers selecting respiration and aeration parameters by randomly sampling from the values obtained from the data. Two synthetic time series were created, one where respiration and aeration were independent of temperature and a second where respiration and aeration were affected by temperature according to the modified Arrhenius relationship. With these two synthetic time series, we again recovered the respiration and aeration input parameters using the night- time regression method and compared those recovered parameters with the input parameters. Because the simulations were conducted with parameters that were known, the values recovered using the night-time regression method (i.e post-simulation) could be compared with parameters driving the simulation (i.e. pre-simulation input values). For values based on data, we found a strong correlation between the aeration constant and respiration for both rivers. For the synthetic time series, no such correlation was found, either with the temperature independent or temperature dependent time series. The night-time regression method also recovered perfectly the input parameters, so the correlation was not brought about as a result of implementing the method itself. We are currently investigating the cause of the correlation.

  16. Dissolved, Exsolved and Re-dissolved H2O in Volcanology: Rheology, Glass Transition, and Thermodynamics

    NASA Astrophysics Data System (ADS)

    Russell, K.; kennedy, B.; Giordano, D.; Friedlander, E. A.

    2012-12-01

    All natural magmas originate with dissolved H2O. All such magmas degas during transport and eruption. The presence, abundance, and state of H2O in magmas control phase relations and the transport properties of melts and magmas. For example, dissolved H2O lowers viscosity, lowers glass transition temperatures (Tg), and controls the temperature and nature of crystallization. The effects of exsolved water are also substantial in terms of modifying the bulk transport properties of the magma, facilitating egress of volatiles and, thus, promoting crystallization. Of great interest is the coupling this component (H2O) creates between the thermodynamic processes (i.e. cooling, crystallization, vesiculation) and the properties (i.e. density, viscosity) controlling the mechanical behaviour (i.e. flow and fracture) of magma during transport and eruption. The coupling allows for strong feedbacks between system variables. The component H2O also has a retrograde solubility in silicate melts wherein H2O solubility in the melt increases with decreasing T. Here, we explore some of the consequences of retrograde solubility of H2O for volcanic systems using a new preliminary experimental dataset. These data establish the 1-atmosphere solubility limits of H2O in silicic melt at volcanic temperatures and are complementary to the growing literature on the low pressure (<50 MPa) solubility of volatiles in silicate melts (e.g., Behrens et al. 2009; DiMatteo et al. 2004; Liu et al. 2005; Zhang 1999). We specifically look at the implications of these data, especially the retrograde solubility limits, for welding of pyroclastic deposits (e.g. ignimbrites, conduit fill, fall out). The cessation of welding and compaction processes in pyroclastic deposits is reached when deposits cool below Tg. However, the fact that H2O has a retrograde solubility means that inter- and intraclast water will be resorbed by vitric pyroclasts as the deposit cools (regardless of load). This has the immediate

  17. EFFECTS OF SUSPENDED SEDIMENTS ON PHOTOLYSIS RATES OF DISSOLVED POLLUTANTS

    EPA Science Inventory

    Data are presented concerning the effects of suspended sediments upon photolysis rates of dissolved ultraviolet (u.v.) absorbing pollutants. The malachite green leucocyanide actinometer was found to be a convenient and sensitive device for measurement of solar u.v. radiation (abo...

  18. TOTAL DISSOLVED AND BIOAVAILABLE METALS AT LAKE TEXOMA MARINAS

    EPA Science Inventory

    Dissolved metals in water and total metals in sediments have been measured at marina areas in Lake Texoma during June 1999 to October 2001, and October 2001, respectively. The metals most often found in the highest concentrations in marina water were Na and Ca, followed by Mg an...

  19. Effects of elevated total dissolved solids on bivalves

    EPA Science Inventory

    A series of experiments were performed to assess the toxicity of different dominant salt recipes of excess total dissolved solids (TDS) to organisms in mesocosms. Multiple endpoints were measured across trophic levels. We report here the effects of four different TDS recipes on b...

  20. Dissolving Carboxylic Acids and Primary Amines on the Overhead Projector

    ERIC Educational Resources Information Center

    Solomon, Sally D.; Rutkowsky, Susan A.

    2010-01-01

    Liquid carboxylic acids (or primary amines) with limited solubility in water are dissolved by addition of aqueous sodium hydroxide (or hydrochloric acid) on the stage of an overhead projector using simple glassware and very small quantities of chemicals. This effective and colorful demonstration can be used to accompany discussions of the…

  1. Optimization of fast dissolving etoricoxib tablets prepared by sublimation technique.

    PubMed

    Patel, D M; Patel, M M

    2008-01-01

    The purpose of this investigation was to develop fast dissolving tablets of etoricoxib. Granules containing etoricoxib, menthol, crospovidone, aspartame and mannitol were prepared by wet granulation technique. Menthol was sublimed from the granules by exposing the granules to vacuum. The porous granules were then compressed in to tablets. Alternatively, tablets were first prepared and later exposed to vacuum. The tablets were evaluated for percentage friability and disintegration time. A 3(2) full factorial design was applied to investigate the combined effect of 2 formulation variables: amount of menthol and crospovidone. The results of multiple regression analysis indicated that for obtaining fast dissolving tablets; optimum amount of menthol and higher percentage of crospovidone should be used. A surface response plots are also presented to graphically represent the effect of the independent variables on the percentage friability and disintegration time. The validity of a generated mathematical model was tested by preparing a checkpoint batch. Sublimation of menthol from tablets resulted in rapid disintegration as compared with the tablets prepared from granules that were exposed to vacuum. The optimized tablet formulation was compared with conventional marketed tablets for percentage drug dissolved in 30 min (Q(30)) and dissolution efficiency after 30 min (DE(30)). From the results, it was concluded that fast dissolving tablets with improved etoricoxib dissolution could be prepared by sublimation of tablets containing suitable subliming agent. PMID:20390084

  2. Investigating Factors that Affect Dissolved Oxygen Concentration in Water

    ERIC Educational Resources Information Center

    Jantzen, Paul G.

    1978-01-01

    Describes activities that demonstrate the effects of factors such as wind velocity, water temperature, convection currents, intensity of light, rate of photosynthesis, atmospheric pressure, humidity, numbers of decomposers, presence of oxidizable ions, and respiration by plants and animals on the dissolved oxygen concentration in water. (MA)

  3. Optimization of Fast Dissolving Etoricoxib Tablets Prepared by Sublimation Technique

    PubMed Central

    Patel, D. M.; Patel, M. M.

    2008-01-01

    The purpose of this investigation was to develop fast dissolving tablets of etoricoxib. Granules containing etoricoxib, menthol, crospovidone, aspartame and mannitol were prepared by wet granulation technique. Menthol was sublimed from the granules by exposing the granules to vacuum. The porous granules were then compressed in to tablets. Alternatively, tablets were first prepared and later exposed to vacuum. The tablets were evaluated for percentage friability and disintegration time. A 32 full factorial design was applied to investigate the combined effect of 2 formulation variables: amount of menthol and crospovidone. The results of multiple regression analysis indicated that for obtaining fast dissolving tablets; optimum amount of menthol and higher percentage of crospovidone should be used. A surface response plots are also presented to graphically represent the effect of the independent variables on the percentage friability and disintegration time. The validity of a generated mathematical model was tested by preparing a checkpoint batch. Sublimation of menthol from tablets resulted in rapid disintegration as compared with the tablets prepared from granules that were exposed to vacuum. The optimized tablet formulation was compared with conventional marketed tablets for percentage drug dissolved in 30 min (Q30) and dissolution efficiency after 30 min (DE30). From the results, it was concluded that fast dissolving tablets with improved etoricoxib dissolution could be prepared by sublimation of tablets containing suitable subliming agent. PMID:20390084

  4. RESPONSE OF LEAD SOLUBILITY TO DISSOLVED CARBONATE IN DRINKING WATER

    EPA Science Inventory

    A model is presented showing the detailed response of the theoretical solubility curves for lead to changes in dissolved inorganic carbonate concentration (TIC) and pH at 25 C. Aqueous Pb(II) ion, lead carbonate complexes, lead hydroxide monomers and polymers, and the solids lead...

  5. Dissolved Organic Matter and Emerging Contaminants in Urban Stream Ecosystems

    NASA Astrophysics Data System (ADS)

    Kaushal, S. S.; Findlay, S.; Groffman, P.; Belt, K.; Delaney, K.; Sides, A.; Walbridge, M.; Mayer, P.

    2009-05-01

    We investigated the effects of urbanization on the sources, bioavailability and forms of natural and anthropogenic organic matter found in streams located in Maryland, U.S.A. We found that the abundance, biaoavailability, and enzymatic breakdown of dissolved organic carbon (DOC), dissolved organic nitrogen (DON), and dissolved organic phosphorus (DOP) increased in streams with increasing watershed urbanization suggesting that organic nutrients may represent a growing form of nutrient loading to coastal waters associated with land use change. Organic carbon, nitrogen, and phosphorus in urban streams were elevated several-fold compared to forest and agricultural streams. Enzymatic activities of stream microbes in organic matter decomposition were also significantly altered across watershed land use. Chemical characterization suggested that organic matter in urban streams originated from a variety of sources including terrestrial, sewage, and in-stream transformation. In addition, a characterization of emerging organic contaminants (polyaromatic cyclic hydrocarbons, organochlorine pesticides, and polybrominated diphenyl ether flame retardents), showed that organic contaminants and dissolved organic matter increase with watershed urbanization and fluctuate substantially with changing climatic conditions. Elucidating the emerging influence of urbanization on sources, transport, and in-stream transformation of organic nutrients and contaminants will be critical in unraveling the changing role of organic matter in urban degraded and restored stream ecosystems.

  6. Reduction of Dissolved Oxygen at a Copper Rotating Disc Electrode

    ERIC Educational Resources Information Center

    Kear, Gareth; Albarran, Carlos Ponce-de-Leon; Walsh, Frank C.

    2005-01-01

    Undergraduates from chemical engineering, applied chemistry, and environmental science courses, together with first-year postgraduate research students in electrochemical technology, are provided with an experiment that demonstrates the reduction of dissolved oxygen in aerated seawater at 25°C. Oxygen reduction is examined using linear sweep…

  7. Dissolved oxygen: method comparison with potentiometric stripping analysis

    SciTech Connect

    Fayyad, M.; Tutunji, M.; Ramakrishna, R.S.; Taha, Z.

    1987-04-01

    Three methods for determination of dissolved oxygen in samples of natural water are compared; potentiometric stripping analysis, PSA compares well with oxygen selective electrodes. Although potentiometric stripping analysis and oxygen selective electrode methods are found to be simple, rapid and of higher reproducibility than the usual Winkler procedure, the use of oxygen selective electrodes has many disadvantages.

  8. Dissolved Trace metal distributions and speciation in Yellow Sea, China

    NASA Astrophysics Data System (ADS)

    Li, Li; Wang, Xiaojing; Zhang, Cuiqin; Liu, Jihua; Shi, Xuefa

    2016-04-01

    Trace metals play an important role in marine biogeochemical cycling processes. However, owing to the lack of trace-metal clean sampling and analytical techniques, high quality data for dissolved trace metals in coastal seawaters of China are scarce. In this study, by employing stringent trace-metal clean sampling and analytical techniques, we investigated spatial distribution patterns of several dissolved trace metals (Cu, Ni, Co, Pb, Cd, Zn, and Ag) in Yellow Sea and Bohai Sea of China, and discussed their potential sources and sinks. In general, the dissolved metal concentrations decreased from Bohai Sea to Yellow Sea, and from nearshore to offshore. Despite the severe contamination status reported in coastal seawaters of China, the trace metal concentrations found in seawater are comparable to the concentrations found in pristine coastal seawaters of the US and the EU. In the meantime, the speciation of several metals (Cu, Pb, Zn, Cd) were also studied with the electrochemical (ASV and CLE-CSV) methods in the Yellow Sea. Natural organic ligands were found in seawaters that strongly complexed with dissolved metals. The concentrations and binding constants of the complexing ligands for each metal were reported and compared with the ones found in other coastal seawaters.

  9. Dissolved oxygen concentration affects hybrid striped bass growth

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Management of dissolved oxygen (DO) concentration in ponds at night during the growing season is important because fish growth and yield are greater in ponds with higher nightly DO concentrations. Three studies were conducted to quantify performance traits and metabolic responses of hybrid striped b...

  10. Do soils loose phosphorus with dissolved organic matter?

    NASA Astrophysics Data System (ADS)

    Kaiser, K.; Brödlin, D.; Hagedorn, F.

    2014-12-01

    During ecosystem development and soil formation, primary mineral sources of phosphorus are becoming increasingly depleted. Inorganic phosphorus forms tend to be bound strongly to or within secondary minerals, thus, are hardly available to plants and are not leached from soil. What about organic forms of phosphorus? Since rarely studied, little is known on the composition, mobility, and bioavailability of dissolved organic phosphorus. There is some evidence that plant-derived compounds, such as phytate, bind strongly to minerals as well, while microbial compounds, such as nucleotides and nucleic acids, may represent more mobile fractions of soil phosphorus. In some weakly developed, shallow soils, leaching losses of phosphorus seem to be governed by mobile organic forms. Consequently, much of the phosphorus losses observed during initial stages of ecosystem development may be due to the leaching of dissolved organic matter. However, the potentially mobile microbial compounds are enzymatically hydrolysable. Forest ecosystems on developed soils already depleted in easily available inorganic phosphorus are characterized by rapid recycling of organic phosphors. That can reduce the production of soluble forms of organic phosphorus as well as increase the enzymatic hydrolysis and subsequent plant uptake of phosphorus bound within dissolved organic matter. This work aims at giving an outlook to the potential role of dissolved organic matter in the cycling of phosphorus within developing forest ecosystems, based on literature evidence and first results of ongoing research.

  11. CONDUCTOMETRIC CHARACTERIZATION OF DISSOLVED HUMIC MATERIALS. (R828158)

    EPA Science Inventory

    Conductometric replacement titrations of humic and fulvic acids dissolved in a slight excess of hydroxide were carried out with standard acid. The slope of the titration curve corresponding to the protonation of humate/fulvate was related to the electrophoretic mobility of the...

  12. FIELD MEASUREMENT OF DISSOLVED OXYGEN: A COMPARISON OF METHODS

    EPA Science Inventory

    The ability to confidently measure the concentration of dissolved oxygen (D.O.) in ground water is a key aspect of remedial selection and assessment. Presented here is a comparison of the commonly practiced methods for determining D.O. concentrations in ground water, including c...

  13. Leachability of dissolved chromium in asphalt and concrete surfacing materials.

    PubMed

    Kayhanian, Masoud; Vichare, Akshay; Green, Peter G; Harvey, John

    2009-08-01

    Leachate metal pollutant concentrations produced from different asphalt and concrete pavement surfacing materials were measured under controlled laboratory conditions. The results showed that, in general, the concentrations of most metal pollutants were below the reporting limits. However, dissolved chromium was detected in leachate from concrete (but not asphalt) specimens and more strongly in the early-time leachate samples. As the leaching continued, the concentration of Cr decreased to below or close to the reporting limit. The source of the chromium in concrete pavement was found to be cement. The concentration of total Cr produced from leachate of different cement coming from different sources that was purchased from retail distributors ranged from 124 to 641mug/L. This result indicates that the potential leachability of dissolved Cr from concrete pavement materials can be reduced through source control. The results also showed that the leachability of dissolved Cr in hardened pavement materials was substantially reduced. For example, the concentration of dissolved Cr measured in actual highway runoff was found to be much lower than the Cr concentration produced from leachate of both open and dense graded concrete pavement specimens under controlled laboratory study. It was concluded that pavement materials are not the source of pollutants of concern in roadway runoff; rather most pollutants in roadway surface runoff are generated from other road-use or land-use sources, or from (wet or dry) atmospheric deposition. PMID:19604624

  14. The Placebo Effect: Dissolving the Expectancy Versus Conditioning Debate

    ERIC Educational Resources Information Center

    Stewart-Williams, Steve; Podd, John

    2004-01-01

    The authors review the literature on the 2 main models of the placebo effect: expectancy theory and classical conditioning. A path is suggested to dissolving the theoretical impasse that has long plagued this issue. The key is to make a clear distinction between 2 questions: What factors shape placebo effects? and What learning mediates the…

  15. PROCESS OF DISSOLVING FUEL ELEMENTS OF NUCLEAR REACTORS

    DOEpatents

    Wall, E.M.V.; Bauer, D.T.; Hahn, H.T.

    1963-09-01

    A process is described for dissolving stainless-steelor zirconium-clad uranium dioxide fuel elements by immersing the elements in molten lead chloride, adding copper, cuprous chloride, or cupric chloride as a catalyst and passing chlorine through the salt mixture. (AEC)

  16. REMOVAL OF HUMICSUBSTANCES AND ALGAE BY DISSOLVED AIR FLOTATION

    EPA Science Inventory

    Dissolved air flotation (DAF) is used in place of conventional gravity settling as a means to separate low density floc particles from water. The following objectives were: (1) to compare DAF to conventional water treatment of coagulation-flocculation followed by gravity settling...

  17. Dissolved oxygen analysis, TMDL model comparison, and particulate matter shunting—Preliminary results from three model scenarios for the Klamath River upstream of Keno Dam, Oregon

    USGS Publications Warehouse

    Sullivan, Annett B.; Rounds, Stewart A.; Deas, Michael L.; Sogutlugil, I. Ertugrul

    2012-01-01

    Efforts are underway to identify actions that would improve water quality in the Link River to Keno Dam reach of the Upper Klamath River in south-central Oregon. To provide further insight into water-quality improvement options, three scenarios were developed, run, and analyzed using previously calibrated CE-QUAL-W2 hydrodynamic and water-quality models. Additional scenarios are under development as part of this ongoing study. Most of these scenarios evaluate changes relative to a "current conditions" model, but in some cases a "natural conditions" model was used that simulated the reach without the effect of point and nonpoint sources and set Upper Klamath Lake at its Total Maximum Daily Load (TMDL) targets. These scenarios were simulated using a model developed by the U.S. Geological Survey (USGS) and Watercourse Engineering, Inc. for the years 2006–09, referred to here as the "USGS model." Another model of the reach was developed by Tetra Tech, Inc. for years 2000 and 2002 to support the Klamath River TMDL process; that model is referred to here as the "TMDL model." The three scenarios described in this report included (1) an analysis of whether this reach of the Upper Klamath River would be in compliance with dissolved oxygen standards if sources met TMDL allocations, (2) an application of more recent datasets to the TMDL model with comparison to results from the USGS model, and (3) an examination of the effect on dissolved oxygen in the Klamath River if particulate material were stopped from entering Klamath Project diversion canals. Updates and modifications to the USGS model are in progress, so in the future these scenarios will be reanalyzed with the updated model and the interim results presented here will be superseded. Significant findings from this phase of the investigation include: * The TMDL analysis used depth-averaged dissolved oxygen concentrations from model output for comparison with dissolved oxygen standards. The Oregon dissolved oxygen

  18. Quantification of dissolved iron sources to the North Atlantic Ocean.

    PubMed

    Conway, Tim M; John, Seth G

    2014-07-10

    Dissolved iron is an essential micronutrient for marine phytoplankton, and its availability controls patterns of primary productivity and carbon cycling throughout the oceans. The relative importance of different sources of iron to the oceans is not well known, however, and flux estimates from atmospheric dust, hydrothermal vents and oceanic sediments vary by orders of magnitude. Here we present a high-resolution transect of dissolved stable iron isotope ratios (δ(56)Fe) and iron concentrations ([Fe]) along a section of the North Atlantic Ocean. The different iron sources can be identified by their unique δ(56)Fe signatures, which persist throughout the water column. This allows us to calculate the relative contribution from dust, hydrothermal venting and reductive and non-reductive sedimentary release to the dissolved phase. We find that Saharan dust aerosol is the dominant source of dissolved iron along the section, contributing 71-87 per cent of dissolved iron. Additional sources of iron are non-reductive release from oxygenated sediments on the North American margin (10-19 per cent), reductive sedimentary dissolution on the African margin (1-4 per cent) and hydrothermal venting at the Mid-Atlantic Ridge (2-6 per cent). Our data also indicate that hydrothermal vents in the North Atlantic are a source of isotopically light iron, which travels thousands of kilometres from vent sites, potentially influencing surface productivity. Changes in the relative importance of the different iron sources through time may affect interactions between the carbon cycle and climate. PMID:25008528

  19. Dissolved amino acids in oceanic basaltic basement fluids

    NASA Astrophysics Data System (ADS)

    Lin, Huei-Ting; Amend, Jan P.; LaRowe, Douglas E.; Bingham, Jon-Paul; Cowen, James P.

    2015-09-01

    The oceanic basaltic basement contains the largest aquifer on Earth and potentially plays an important role in the global carbon cycle as a net sink for dissolved organic carbon (DOC). However, few details of the organic matter cycling in the subsurface are known because great water depths and thick sediments typically hinder direct access to this environment. In an effort to examine the role of water-rock-microorganism interaction on organic matter cycling in the oceanic basaltic crust, basement fluid samples collected from three borehole observatories installed on the eastern flank of the Juan de Fuca Ridge were analyzed for dissolved amino acids. Our data show that dissolved free amino acids (1-13 nM) and dissolved hydrolyzable amino acids (43-89 nM) are present in the basement. The amino acid concentrations in the ridge-flank basement fluids are at the low end of all submarine hydrothermal fluids reported in the literature and are similar to those in deep seawater. Amino acids in recharging deep seawater, in situ amino acid production, and diffusional input from overlying sediments are potential sources of amino acids in the basement fluids. Thermodynamic modeling shows that amino acid synthesis in the basement can be sustained by energy supplied from inorganic substrates via chemolithotrophic metabolisms. Furthermore, an analysis of amino acid concentrations and compositions in basement fluids support the notion that heterotrophic activity is ongoing. Similarly, the enrichment of acidic amino acids and depletion of hydrophobic ones relative to sedimentary particulate organic matter suggests that surface sorption and desorption also alters amino acids in the basaltic basement. In summary, although the oceanic basement aquifer is a net sink for deep seawater DOC, similar amino acid concentrations in basement aquifer and deep seawater suggest that DOC is preferentially removed in the basement over dissolved amino acids. Our data also suggest that organic carbon

  20. Photochemical Flocculation of Terrestrial Dissolved Organic Matter (tDOM) and Iron: Mechanisms and Geochemical Implications

    NASA Astrophysics Data System (ADS)

    Mopper, K.; Helms, J. R.; Mao, J.; Abdulla, H. A.; Schmidt-Rohr, K.

    2013-12-01

    Photoflocculation of DOM has received relatively little attention. No previous studies have examined the chemical composition of the flocs nor investigated the coagulation mechanisms. We observed that, after 30 days of simulated solar UV irradiation of 0.1-um filtered Great Dismal Swamp (Virginia) water, 7.1% of the DOC was converted to POC while 75% was remineralized. Approximately 87% of the iron was removed from the dissolved phase after 30 days, but iron did not flocculate until a major fraction of DOM was removed by photochemical degradation and flocculation (>10 days); thus, during the initial 10 days, there were sufficient organic ligands present and/or the pH was low enough to keep iron in solution. Although photoflocculation of iron did eventually occur, it is not clear if iron is required for the initial flocculation of DOM. Using NMR and FT-IR techniques, we found that photochemically flocculated POM was enriched in aliphatics and amide functionality relative to the residual non-flocculated DOM, while carbohydrate-like material was neither photochemical degraded nor flocculated. Based on this spectroscopic evidence, we propose several mechanisms for the formation of the flocs during irradiation. We also speculate that abiotic photochemical flocculation may remove a significant fraction of tDOM and iron from the upper water column between headwaters and the ocean, including estuaries. Fig. 1. Concentrations of dissolved (gray), particulate (black), and adsorbed (white) material as a function of irradiation time: (a) organic carbon, (b) absorption at 300 nm, (c) total iron by atomic absorption, and (d) total nitrogen. Error bars represent the combined standard deviations of the 'total,' 'dissolved,' and 'adsorbed' terms from which the 'particulate' term was calculated. Total nitrogen was not determined for the 'adsorbed' material

  1. Direct and dissolved oxygen involved photodegradation of MeO-PBDEs in water.

    PubMed

    Xue, Weifeng; Chen, Jingwen; Xie, Qing

    2016-04-15

    Photodegradation has been proved to be a crucial way of elimination for polybrominated diphenyl ethers (PBDEs) and hydroxylated PBDEs (HO-PBDEs). However, it is still unknown whether methoxylated PBDEs (MeO-PBDEs) can also undergo photodegradation. In this study, 4'-MeO-BDE-17, 5-MeO-BDE-47, 5'-MeO-BDE-99, 6-MeO-BDE-47 and 6-MeO-BDE-85 were selected as targets to investigate their photodegradation in water. Meanwhile, the effects of dissolved oxygen on the photoreactions of MeO-PBDEs were also unveiled. Simulated sunlight experiments indicate that 6-MeO-BDE-47 resisted photodegradation for 20h, while other MeO-PBDEs underwent relatively fast photodegradation, which was greatly susceptible to the substitution patterns of methoxyl and bromine. Photo-excited MeO-PBDEs (except 6-MeO-BDE-47) can sensitize dissolved oxygen to generate singlet oxygen ((1)O2) and superoxide anion radical (O2(-)). The generated (1)O2 cannot degrade the MeO-PBDEs, whereas O2(-) was reactive with MeO-PBDEs. The contribution of dissolved oxygen to the photodegradation of 4'-MeO-BDE-17 and 6-MeO-BDE-85 was negligible; while the negative contribution was observed for 5-MeO-BDE-47 and 5'-MeO-BDE-99. Hydrodebromination was a crucial photodegradation pathway for MeO-PBDEs (excluding 4'-MeO-BDE-17 and 6-MeO-BDE-47). Eventually, direct photolysis half-lives of MeO-PBDEs except 6-MeO-BDE-47 in the surface waters at 40 N latitude were calculated to be 1.35-3.46d in midsummer and 6.39-17.47d in midwinter. PMID:26802632

  2. Changes in glucose fermentation pathways by an enriched bacterial culture in response to regulated dissolved H2 concentrations.

    PubMed

    Zheng, Hang; Zeng, Raymond J; Duke, Mikel C; O'Sullivan, Cathryn A; Clarke, William P

    2015-06-01

    It is well established that metabolic pathways in the fermentation of organic waste are primarily controlled by dissolved H2 concentrations, but there is no reported study that compares observed and predicted shifts in fermentation pathways induced by manipulating the dissolved H2 concentration. A perfusion system is presented that was developed to control dissolved H2 concentrations in the continuous fermentation of glucose by a culture highly enriched towards Thermoanaerobacterium thermosaccharolyticum (86 ± 9% relative abundance) from an originally diverse consortia in the leachate of a laboratory digester fed with municipal solid waste. Media from a 2.5 L CSTR was drawn through sintered steel membrane filters to retain biomass, allowing vigorous sparging in a separate chamber without cellular disruption. Through a combination of sparging and variations in glucose feeding rate from 0.8 to 0.2 g/L/d, a range of steady state fermentations were performed with dissolved H2 concentrations as low as an equivalent equilibrated H2 partial pressure of 3 kPa. Trends in product formation rates were simulated using a H2 regulation partitioning model. The model correctly predicted the direction of products redistribution in response to H2 concentration changes and the acetate and butyrate formation rates when H2 concentrations were less than 6 kPa. However, the model over-estimated acetate, ethanol and butanol productions at the expense of butyrate production at higher H2 concentrations. The H2 yield at the lowest dissolved H2 concentration was 2.67 ± 0.08 mol H2 /mol glucose, over 300% higher than the yield achieved in a CSTR operated without sparging. PMID:25545692

  3. Pathways and transformations of dissolved methane and dissolved inorganic carbon in Arctic tundra soils: Evidence from analysis of stable isotopes

    NASA Astrophysics Data System (ADS)

    Throckmorton, H.; Perkins, G.; Muss, J. D.; Smith, L. J.; Conrad, M. E.; Torn, M. S.; Heikoop, J. M.; Newman, B. D.; Wilson, C. J.; Wullschleger, S. D.

    2014-12-01

    Arctic soils contain a large pool of terrestrial C and are of great interest because of their potential for releasing significant amounts of carbon dioxide (CO2) and methane (CH4) to the atmosphere. Few attempts have been made, however, to derive quantitative budgets of CO2 and CH4 budgets for high-latitude ecosystems. Therefore, this study used naturally occurring geochemical and isotopic tracers to estimate production pathways and transformations of dissolved inorganic carbon (DIC = Σ (total) dissolved CO2) and dissolved CH4 in soil pore waters from 17 locations (drainages) in Barrow, Alaska (USA) in July and September, 2013; and to approximate a complete balance of belowground C cycling at our sampling locations. Results suggest that CH4 was primarily derived from biogenic acetate fermentation, with a shift at 4 locations from July to September towards CO2 reduction as the dominant methanogenic pathway. A large majority of CH4 produced at the frost table methane was transferred directly to the atmosphere via plant roots and ebullition (94.0 ± 1.4% and 96.6 ± 5.0% in July and September). A considerable fraction of the remaining CH4 was oxidized to CO2 during upward diffusion in July and September, respectively. Methane oxidization produced <1% of CO2 relative to alternative production mechanisms in deep subsurface pore waters. The majority of subsurface CO2 was produced from anaerobic respiration, likely due to reduction of Fe oxides and humics (52 ± 6 to 100 ± 13%, on average) while CO2 produced from methanogenesis accounted for the remainder (0 ± 13% to 47 ± 6%, on average) for July and September, respectively. Dissolved CH4 and dissolved CO2 concentrations correlated with thaw depth, suggesting that Arctic ecosystems will likely produce and release a greater amount of greenhouse gasses under projected warming and deepening of active layer thaw depth under future climate change scenarios.

  4. Seasonal variability of total dissolved fluxes and origin of major dissolved elements within a large tropical river: The Orinoco, Venezuela

    NASA Astrophysics Data System (ADS)

    Laraque, Alain; Moquet, Jean-Sébastien; Alkattan, Rana; Steiger, Johannes; Mora, Abrahan; Adèle, Georges; Castellanos, Bartolo; Lagane, Christèle; Lopez, José Luis; Perez, Jesus; Rodriguez, Militza; Rosales, Judith

    2013-07-01

    Seasonal variations of total dissolved fluxes of the lower Orinoco River were calculated taking into account four complete hydrological cycles during a five-year period (2005-2010). The modern concentrations of total dissolved solids (TDS) of the Orinoco surface waters were compared with data collected during the second half of the last century published in the literature. This comparison leads to the conclusion that chemical composition did not evolve significantly at least over the last thirty to forty years. Surface waters of the Orinoco at Ciudad Bolivar are between bicarbonated calcic and bicarbonated mixed. In comparison to mean values of concentrations of total dissolved solids (TDS) of world river surface waters (89.2 mg l-1), the Orinoco River at Ciudad Bolivar presents mainly low mineralized surface waters (2005-10: TDS 30 mg l-1). The TDS fluxes passing at this station in direction to the Atlantic Ocean between 2005 and 2010 were estimated at 30 × 106 t yr-1, i.e. 36 t km-2 yr-1. It was observed that the seasonal variations (dry season vs wet season) of total dissolved fluxes (TDS and dissolved organic carbon (DOC)) are mainly controlled by discharge variations. Two groups of elements have been defined from dilution curves and molar ratio diagrams. Ca2+, Mg2+, HCO3-, Cl- and Na+ mainly come from the same geographic and lithologic area, the Andes. K+ and SiO2 essentially come from the Llanos and the Guayana Shield. These findings are important for understanding fundamental geochemical processes within the Orinoco River basin, but also as a baseline study in the perspective of the development of numerous mining activities related with aluminum and steel industries; and the plans of the Venezuelan government to construct new fluvial ports on the lower Orinoco for the transport of hydrocarbons.

  5. Brine-induced advection of dissolved aromatic hydrocarbons to arctic bottom waters

    SciTech Connect

    Payne, J.R. ); Hachmeister, L.E. ); McNabb, G.D. Jr. ); Smith, G.S. ); Manen, C.A. ); Sharpe, H.E.

    1991-05-01

    Extruded brine, generated during sea ice formation in nearshore arctic waters, will sink to the bottom and can form a stable bottom boundary layer. This layer can persist for periods of up to 4-6 months. Limited quantities of dissolved aromatic hydrocarbons resulting from a spill of crude oil or refined petroleum distillate products during periods of ice growth can be transported as conservative components to the benthos with sinking brine. Once incorporated into the stable bottom boundary layer, these aromatic components are no longer subject to loss by evaporative processes, and they only can be diluted by ultimately mixing with uncontaminated water masses, a process that proceeds slowly throughout the ice-covered period. This mechanism for the transport of dissolved hydrocarbons has been demonstrated through a laboratory test-tank simulation and a chemical/physical oceanographic field program conducted in the Chukchi Sea near Pt. Frankline, AK (March 1985). The results are pertinent to shallow nearshore oil and gas exploration, development, production, and transportation activities in high latitude marine systems.

  6. Direct photolysis of carbonyl compounds dissolved in cloud and fog droplets

    NASA Astrophysics Data System (ADS)

    Epstein, S. A.; Tapavicza, E.; Furche, F.; Nizkorodov, S. A.

    2013-04-01

    Gas phase photolysis is an important tropospheric sink for many carbonyl compounds, however the significance of direct photolysis of carbonyl compounds dissolved in cloud and fog droplets is uncertain. We develop a theoretical approach to assess the importance of aqueous photolysis for a series of carbonyls that possess carboxyl and hydroxyl functional groups by comparison with rates of other atmospheric processes. We use computationally and experimentally derived Henry's law parameters, hydration equilibrium parameters, aqueous hydroxyl radical (OH) rate constants, and optical extinction coefficients to identify types of compounds that will not have competitive aqueous photolysis rates. We also present molecular dynamics simulations of atmospherically relevant carbonyl compounds designed to estimate gas and aqueous phase extinction coefficients. In addition, experiments designed to measure the photolysis rate of glyceraldehyde, an atmospherically relevant water soluble organic compound, reveal that aqueous quantum yields are highly molecule-specific and cannot be extrapolated from measurements of structurally similar compounds. We find that only three out of the 92 carbonyl compounds investigated, pyruvic acid, 3-oxobutanoic acid, and 3-oxopropanoic acid, may have aqueous photolysis rates that exceed the rate of oxidation by dissolved OH. For almost all carbonyl compounds lacking α, β conjugation, atmospheric removal by direct photolysis in cloud and fog droplets can be neglected.

  7. Temporal scale-induced uncertainty in load duration curves for instream-dissolved oxygen.

    PubMed

    Patil, Abhijit; Deng, Zhiqiang; Malone, Ronald F

    2013-02-01

    Load duration curves were developed using the Hydrological Simulation Program FORTRAN (HSPF) for dissolved oxygen (DO) for the Amite River in Louisiana, USA. The concept of 'dissolved oxygen reserve', defined as the total quantity of DO, is introduced. The effect of temporal resolution on duration curves of DO reserve was examined using duration curves developed based on daily, weekly, biweekly, and monthly average data. Duration curves for DO exhibited high variability in the load estimated using daily data as compared to those based on biweekly and monthly data. A seasonal analysis revealed the trend in the DO reserve. The daily DO reserve for the Amite River at Port Vincent was 44,049.31 kg when daily summer data were used and 74,255.15 kg for daily annual data. A surplus of 10,691 kg of DO reserve was shown in the monthly data during critical summer months. The coefficient of variation (CV), used to define the temporal scale-induced uncertainty, was found to be linearly and inversely correlated with the logarithm of the time scale. Regression equations were developed to extrapolate near real-time flow and water quality data, greatly simplifying flow and water quality monitoring and reducing the cost involved in flow and water quality monitoring. PMID:22623167

  8. Impact of solute concentration on the electrocatalytic conversion of dissolved gases in buffered solutions

    NASA Astrophysics Data System (ADS)

    Shinagawa, Tatsuya; Takanabe, Kazuhiro

    2015-08-01

    To maintain local pH levels near the electrode during electrochemical reactions, the use of buffer solutions is effective. Nevertheless, the critical effects of the buffer concentration on electrocatalytic performances have not been discussed in detail. In this study, two fundamental electrochemical reactions, oxygen reduction reaction (ORR) and hydrogen oxidation reaction (HOR), on a platinum rotating disk electrode are chosen as model gas-related aqueous electrochemical reactions at various phosphate concentrations. Our detailed investigations revealed that the kinetic and limiting diffusion current densities for both the ORR and HOR logarithmically decrease with increasing solute concentration (log |jORR | = - 0.39 c + 0.92 , log |jHOR | = - 0.35 c + 0.73) . To clarify the physical aspects of this phenomenon, the electrolyte characteristics are addressed: with increasing phosphate concentration, the gas solubility decrease, the kinematic viscosity of the solution increase and the diffusion coefficient of the dissolved gases decrease. The simulated limiting diffusion currents using the aforementioned parameters match the measured ones very well (log |jORR | = - 0.43 c + 0.99 , log |jHOR | = - 0.40 c + 0.54) , accurately describing the consequences of the electrolyte concentration. These alterations of the electrolyte properties associated with the solute concentration are universally applicable to other aqueous gas-related electrochemical reactions because the currents are purely determined by mass transfer of the dissolved gases.

  9. Direct photolysis of carbonyl compounds dissolved in cloud and fog~droplets

    NASA Astrophysics Data System (ADS)

    Epstein, S. A.; Tapavicza, E.; Furche, F.; Nizkorodov, S. A.

    2013-09-01

    Gas-phase photolysis is an important tropospheric sink for many carbonyl compounds; however the significance of direct photolysis of these compounds dissolved in cloud and fog droplets is uncertain. We develop a theoretical approach to assess the importance of aqueous photolysis for a series of carbonyls that possess carboxyl and hydroxyl functional groups by comparison with rates of other atmospheric processes. We use computationally and experimentally derived effective Henry's law constants, hydration equilibrium parameters, aqueous hydroxyl radical (OH) rate constants, and optical extinction coefficients to identify types of compounds that will (or will not) have competitive aqueous photolysis rates. We also present molecular dynamics simulations designed to estimate gas- and aqueous-phase extinction coefficients of unstudied atmospherically relevant compounds found in d-limonene and isoprene secondary organic aerosol. In addition, experiments designed to measure the photolysis rate of glyceraldehyde, an atmospherically relevant water-soluble organic compound, reveal that aqueous quantum yields are highly molecule-specific and cannot be extrapolated from measurements of structurally similar compounds. We find that only two out of the 92 carbonyl compounds investigated, pyruvic acid and acetoacetic acid, may have aqueous photolysis rates that exceed the rate of oxidation by dissolved OH. For almost all carbonyl compounds lacking α,β-conjugation that were investigated, atmospheric removal by direct photolysis in cloud and fog droplets can be neglected under typical atmospheric conditions.

  10. Dissolved oxygen regulation by logarithmic/antilogarithmic control to improve a wastewater treatment process.

    PubMed

    Flores, Victor R; Sanchez, Edgar N; Béteau, Jean-François; Hernandez, Salvador Carlos

    2013-01-01

    This paper presents the automation of a real activated sludge wastewater treatment plant, which is located at San Antonio Ajijic in Jalisco, Mexico. The main objective is to create an on-line automatic supervision system, and to regulate the dissolved oxygen concentration in order to improve the performances of the process treating municipal wastewater. An approximate mathematical model is determined in order to evaluate via simulations different control strategies: proportional integral (PI), fuzzy PI and PI Logarithm/Antilogarithm (PI L/A). The controlled variable is dissolved oxygen and the control input is the injected oxygen. Based on this evaluation, the PI L/A controller is selected to be implemented in the real process. After that, the implementation, testing and fully operation of the plant automation are described. With this system, the considered wastewater treatment plant save energy and improves the effluent quality; also, the process monitoring is done online and it is easily operated by the plant users. PMID:24617069

  11. Photochemical Oxidation of Dissolved Elemental Mercury by Carbonate Radicals in Water

    DOE PAGESBeta

    He, Feng; Zhao, Weirong; Liang, Liyuan; Gu, Baohua

    2014-11-11

    Photochemical oxidation of dissolved elemental mercury [Hg(0)] affects mercury chemical speciation and its transfer at the water-air interface in the aquatic environment. The mechanisms and factors that control Hg(0) photooxidation, however, are not completely understood, especially in natural freshwaters containing dissolved organic matter (DOM) and carbonate. Here, we evaluate Hg(0) photooxidation rates affected by various reactive ionic species [e.g., DOM, CO32-, NO3-] and free radicals in a creek water and a phosphate buffer solution (pH=8) under simulated solar irradiation. We report a high Hg(0) photooxidation rate (k = 1.44 h-1) in the presence of both HCO32- and NO3-, whereas HCO32-,more » NO3-, or DOM alone increased the oxidation rate slightly (k = 0.1 0.17 h-1). Using scavengers and enhancers for singlet oxygen (1O2) and hydroxyl (HO∙ ) radicals, as well as electron paramagnetic resonance spectroscopy, we identify that carbonate radicals (CO3 ∙-) primarily drive the Hg(0) photooxidation, whereas addition of DOM resulted in a 2-fold decrease in Hg(0) oxidation. This study identifies an unrecognized pathway of Hg(0) photooxidation by CO3 ∙- radicals and the inhibitory effect of DOM, which could be important in assessing Hg transformation and fate in water containing carbonate such as hard water and seawater.« less

  12. Heat as a tracer to estimate dissolved organic carbon flux from a restored wetland

    USGS Publications Warehouse

    Burow, K.R.; Constantz, J.; Fujii, R.

    2005-01-01

    Heat was used as a natural tracer to characterize shallow ground water flow beneath a complex wetland system. Hydrogeologic data were combined with measured vertical temperature profiles to constrain a series of two-dimensional, transient simulations of ground water flow and heat transport using the model code SUTRA (Voss 1990). The measured seasonal temperature signal reached depths of 2.7 m beneath the pond. Hydraulic conductivity was varied in each of the layers in the model in a systematic manual calibration of the two-dimensional model to obtain the best fit to the measured temperature and hydraulic head. Results of a series of representative best-fit simulations represent a range in hydraulic conductivity values that had the best agreement between simulated and observed temperatures and that resulted in simulated pond seepage values within 1 order of magnitude of pond seepage estimated from the water budget. Resulting estimates of ground water discharge to an adjacent agricultural drainage ditch were used to estimate potential dissolved organic carbon (DOC) loads resulting from the restored wetland. Estimated DOC loads ranged from 45 to 1340 g C/(m2 year), which is higher than estimated DOC loads from surface water. In spite of the complexity in characterizing ground water flow in peat soils, using heat as a tracer provided a constrained estimate of subsurface flow from the pond to the agricultural drainage ditch. Copyright ?? 2005 National Ground Water Association.

  13. The availability of dissolved organic phosphorus compounds to marine phytoplankton

    NASA Astrophysics Data System (ADS)

    Hua-Sheng, Hong; Hai-Li, Wang; Bang-Qin, Huang

    1995-06-01

    The availability of three dissolved organic phosphorus (DOP) compounds as nutrient sources for experimental culture of three algae was studied. Results indicated that these compounds could be utilized by algae, and that dissolved inorganic phosphorus (DIP) was first to be uptaken when various forms of phosphorus (DIP and DOP) co-existed. Dicrateria zhanjiangensis' uptake of sodium glycerophosphate was faster than that of D-ribose-5-phosphate. The increase of sodium glycerophosphate had little effect on the maximum uptake rate( V max) of Chlorella sp., but increased the semisaturation constant( K s) remarkably; the photosynthesis rates(PR) of Dicrateria zhanjiangensis and Chlorella sp. were rarely affected by using various forms of phosphorus in the culture experiments. The possible DOP pathways utilized by algae are discussed.

  14. Preparation of encapsulated proteins dissolved in low viscosity fluids.

    PubMed

    Ehrhardt, M R; Flynn, P F; Wand, A J

    1999-05-01

    The majority of proteins are too large to be comprehensively examined by solution NMR methods, primarily because they tumble too slowly in solution. One potential approach to making the NMR relaxation properties of large proteins amenable to modern solution NMR techniques is to encapsulate them in a reverse micelle which is dissolved in a low viscosity fluid. Unfortunately, promising low viscosity fluids such as the short chain alkanes, supercritical carbon dioxide, and various halocarbon refrigerants all require the application of significant pressure to be kept liquefied at room temperature. Here we describe the design and use of a simple cost effective NMR tube suitable for the preparation of solutions of proteins encapsulated in reverse micelles dissolved in such fluids. PMID:10382308

  15. [Quantitative analysis of transformer oil dissolved gases using FTIR].

    PubMed

    Zhao, An-xin; Tang, Xiao-jun; Wang, Er-zhen; Zhang, Zhong-hua; Liu, Jun-hua

    2013-09-01

    For the defects of requiring carrier gas and regular calibration, and low safety using chromatography to on line monitor transformer dissolved gases, it was attempted to establish a dissolved gas analysis system based on Fourier transform infrared spectroscopy. Taking into account the small amount of characteristic gases, many components, detection limit and safety requirements and the difficulty of degasser to put an end to the presence of interference gas, the quantitative analysis model was established based on sparse partial least squares, piecewise section correction and feature variable extraction algorithm using improvement TR regularization. With the characteristic gas of CH4, C2H6, C2H6, and CO2, the results show that using FTIR meets DGA requirements with the spectrum wave number resolution of 1 cm(-1) and optical path of 10 cm. PMID:24369641

  16. Unimodal response of fish yield to dissolved organic carbon.

    PubMed

    Finstad, Anders G; Helland, Ingeborg P; Ugedal, Ola; Hesthagen, Trygve; Hessen, Dag O

    2014-01-01

    Here, we demonstrate a contrasting effect of terrestrial coloured dissolved organic material on the secondary production of boreal nutrient poor lakes. Using fish yield from standardised brown trout gill-net catches as a proxy, we show a unimodal response of lake secondary productivity to dissolved organic carbon (DOC). This suggests a trade-off between positive and negative effects, where the initial increase may hinge upon several factors such as energy subsidising, screening of UV-radiation or P and N load being associated with organic carbon. The subsequent decline in production with further increase in DOC is likely associated with light limitations of primary production. We also show that shallow lakes switch from positive to negative effects at higher carbon loads than deeper lakes. These results underpin the major role of organic carbon for structuring productivity of boreal lake ecosystems. PMID:24165396

  17. Nutrient and dissolved oxygen studies at OTEC sites

    SciTech Connect

    Quinby-Hunt, M.S.; Fanning, K.; Ziemann, D.; Walsh, T.W.; Knauer, G.A.

    1981-07-01

    In order to adequately assess the impact of artificial upwelling and other possible ecological impacts of OTEC operations on the chemistry of the water column at OTEC sites, studies were initiated at several potential sites. At most sites,hydrocasts were taken at approximately noon and midnight to a depth of about 100 m; samples were collected from about 15 depths to be analyzed for nitrates, nitrites, reactive phosphate, silicate and dissolved oxygen. At some sites, samples were analyzed for various other parameters including ammonia, total organic phosphorus and carbonate alkalinity. Preliminary data on nitrates, phosphates, silicates and dissolved oxygen from several potential sites - off Hawaii, Oahu, Peurto Rico, and the Virgin Islands - are presented and compared. Significant differences between nutrient concentrations have been found at the Caribbean and Hawaiian sites. There is also evidence of seasonal variation at the Oahu site. (LEW)

  18. Azomethine H colorimetric method for determining dissolved boron in water

    USGS Publications Warehouse

    Spencer, R.R.; Erdmann, D.E.

    1979-01-01

    An automated colorimetric method for determining dissolved boron in water is described. The boron is complexed with azomethine H, which is readily available as the condensation product of H acid (8-amino-1-naphthol-3,6-disulfonic acid) and salicylaldehyde. The absorbance of the yellow complex formed is then measured colorimetrically at 410 nm. Interference effects from other dissolved species are minimized by the addition of diethylenetriaminepentaacetic acid (DTPA); however, iron, zinc, and bicarbonate interfere at concentrations above 400 ??g/L, 2000 ??g/L, and 200 mg/L, respectively. The bicarbonate interference can be eliminated by careful acidification of the sample with concentrated HCl to a pH between 5 and 6. Thirty samples per hour can be routinely analyzed over the range of from 10 to 400 ??g/L, boron.

  19. Determination of total dissolved solids in water analysis

    USGS Publications Warehouse

    Howard, C.S.

    1933-01-01

    The figure for total dissolved solids, based on the weight of the residue on evaporation after heating for 1 hour at 180??C., is reasonably close to the sum of the determined constituents for most natural waters. Waters of the carbonate type that are high in magnesium may give residues that weigh less than the sum. Natural waters of the sulfate type usually give residues that are too high on account of incomplete drying.

  20. Characteristics of dissolved carbon change in irrigation water

    NASA Astrophysics Data System (ADS)

    Akaike, Y.; Kunishio, A.; Kawamoto, Y.; Murakami, H.; Iwata, T.

    2012-12-01

    It is necessary to estimate carbon emission from soil for understanding carbon cycle processes in cultivated fields. Since irrigation water is introduced into a typical rice paddy field, one part of emitted carbon content from soil were trapped by water and dissolved in it, and dissolved carbon content outflows from the field at the drainage moment. In this study, we continuously and regularly analyzed dissolved carbon content of irrigation water and investigated seasonal variation of efflux of carbon from a paddy field. Experimental site is located reclaimed land in the southern part of Okayama Prefecture, Japan. And rice cropping cultivation has continued in a similar method every year. Intermittent irrigation water managements, or 3 days flooded and 4 days drained condition, were carried out during almost all the period of rice cultivated term. Irrigation water was sampled every flooding and drainage days. Inorganic carbon (IC) concentration was measured with total carbon (TC) analyzer (TOC-V/CSH, SHIMAZU). Amount of dissolved carbon in irrigation water was calculated from product of the carbon concentration and water levels. The experimental paddy field was divided into two areas, and two bottle of water were sampled from each area. In order to investigate what impact is brought on the annual carbon cycle by the difference of disposal management of residual biomass after the harvest, residual biomass was burned and plowed into soil at the one area on 29th Nov., 2011, and residue was not burned and directly plowed into soil at the other area as usual. IC during cultivated term in 2011 and 2012 in both area gradually increased day by day for every flooded periods. And IC showed distinct diurnal variations with lower value in the daytime than at night, it is because of photosynthetic activities by aquatic algae in the irrigation water.

  1. Variability in dissolved oxygen off Eastern Luzon, Philippines

    NASA Astrophysics Data System (ADS)

    San Diego-McGlone, M.; Escobar, M.; Jacinto, G.; Villanoy, C. L.

    2013-12-01

    The eastern coast and shelf of Luzon is a unique area encompassed by the bifurcation of the western boundary North Equatorial Current (NEC) into the Kuroshio and Mindanao Currents. This region is also productive and has become a rich fishing ground. Of interest is how biogeochemistry in this area is influenced by variability in the bifurcation driven by ENSO events, as well as by production and remineralization processes. Results from 2011 and 2012 oceanographic cruises show changes in dissolved oxygen (DO) off Eastern Luzon in both spatial and temporal scales. Between 2011 and 2012, there was a southern shift of the bifurcation latitude. Water masses from the NEC and the Kuroshio Recirculation Gyre (KRG) east of Luzon have inherent low and higher DO concentrations, respectively. A subsurface oxygen minimum layer was seen at 150-200m. Waters with this low dissolved oxygen signature comes from a 400m-deep sill basin (Lamon Deep) off Eastern Luzon. Apart from low ventilation rates, organic matter decomposition contributes to depletion of DO. Proximity of the basin to the coast is evident in the high particulate organic carbon concentration that is delivered from land through run-off and the nearby river. The low DO water is advected offshore and contributes to the spatial variability of DO in the area. Linear regression of particulate organic carbon, dissolved organic carbon, dissolved inorganic carbon, and nutrients with AOU strongly correlate organic matter remineralization to the change in DO with depth. The variability in DO off Eastern Luzon is analyzed with the large-scale variability offshore of source waters to determine the relative influence of biogeochemical cycling in the area.

  2. Sea Water Ageing of GFRP Composites and the Dissolved salts

    NASA Astrophysics Data System (ADS)

    Chakraverty, A. P.; Mohanty, U. K.; Mishra, S. C.; Satapathy, A.

    2015-02-01

    This paper houses the effect of sea water immersion on glass fibre reinforced polymer (GFRP) composites. The major sources of interest are study of sea water absorption, penetration of the dissolved salts, details of chemical and physical bonds at the interface, variations of mechanical properties and study of failure mechanisms as revealed through SEM fractographs. Eighteen ply GFRP composites are immersed in sea water for a period of one year in steps of two months durations. It is revealed that the moisture absorption transforms from a Fickian to non-Fickian behavior with lapse of time. The dissolved salt 'K' shows highest depth of penetration after one year of immersion while 'Na' shows a least depth of penetration, as revealed from the EDS spectra. It is also revealed that 'Ca' seems to have a sudden burst in the rate of penetration even surpassing that of 'K'. This trend can be attributed to the combined effect of ionic mobility of the various dissolved salts and the probable interaction between 'K' and the -OH group of epoxy resin. This interaction between dissolved 'K' and the -OH group in the polymer could have arrested the further advancement of 'K' salts in the polymer, resulting in comparatively high rates of 'Ca' penetration. The mechanical properties such as inter laminar shear stress (ILSS), stress and strain at rupture, glass transition temperature (Tg) and elastic modulus show a decreasing trend with the increased duration of immersion. As revealed from the SEM fractographs pot- holing, fiber pull-out, matrix crack etc. are seen to be the major reason for failure of the immersed samples under load.

  3. Toxicity of dissolved and precipitated aluminium to marine diatoms.

    PubMed

    Gillmore, Megan L; Golding, Lisa A; Angel, Brad M; Adams, Merrin S; Jolley, Dianne F

    2016-05-01

    Localised aluminium contamination can lead to high concentrations in coastal waters, which have the potential for adverse effects on aquatic organisms. This research investigated the toxicity of 72-h exposures of aluminium to three marine diatoms (Ceratoneis closterium (formerly Nitzschia closterium), Minutocellus polymorphus and Phaeodactylum tricornutum) by measuring population growth rate inhibition and cell membrane damage (SYTOX Green) as endpoints. Toxicity was correlated to the time-averaged concentrations of different aluminium size-fractions, operationally defined as <0.025μm filtered, <0.45μm filtered (dissolved) and unfiltered (total) present in solution over the 72-h bioassay. The chronic population growth rate inhibition after aluminium exposure varied between diatom species. C. closterium was the most sensitive species (10% inhibition of growth rate (72-h IC10) of 80 (55-100)μg Al/L (95% confidence limits)) while M. polymorphus (540 (460-600)μg Al/L) and P. tricornutum (2100 (2000-2200)μg Al/L) were less sensitive (based on measured total aluminium). Dissolved aluminium was the primary contributor to toxicity in C. closterium, while a combination of dissolved and precipitated aluminium forms contributed to toxicity in M. polymorphus. In contrast, aluminium toxicity to the most tolerant diatom P. tricornutum was due predominantly to precipitated aluminium. Preliminary investigations revealed the sensitivity of C. closterium and M. polymorphus to aluminium was influenced by initial cell density with aluminium toxicity significantly (p<0.05) increasing with initial cell density from 10(3) to 10(5)cells/mL. No effects on plasma membrane permeability were observed for any of the three diatoms suggesting that mechanisms of aluminium toxicity to diatoms do not involve compromising the plasma membrane. These results indicate that marine diatoms have a broad range in sensitivity to aluminium with toxic mechanisms related to both dissolved and precipitated

  4. Recycle Waste Collection Tank (RWCT) simulant testing in the PVTD feed preparation system

    SciTech Connect

    Abrigo, G.P.; Daume, J.T.; Halstead, S.D.; Myers, R.L.; Beckette, M.R.; Freeman, C.J.; Hatchell, B.K.

    1996-03-01

    (This is part of the radwaste vitrification program at Hanford.) RWCT was to routinely receive final canister decontamination sand blast frit and rinse water, Decontamination Waste Treatment Tank bottoms, and melter off-gas Submerged Bed Scrubber filter cake. In order to address the design needs of the RWCT system to meet performance levels, the PNL Vitrification Technology (PVTD) program used the Feed Preparation Test System (FPTS) to evaluate its equipment and performance for a simulant of RWCT slurry. (FPTS is an adaptation of the Defense Waste Processing Facility feed preparation system and represents the initially proposed Hanford Waste Vitrification Plant feed preparation system designed by Fluor-Daniel, Inc.) The following were determined: mixing performance, pump priming, pump performance, simulant flow characterization, evaporator and condenser performance, and ammonia dispersion. The RWCT test had two runs, one with and one without tank baffles.

  5. Xe-129 NMR of xenon dissolved in biological media.

    NASA Astrophysics Data System (ADS)

    Mazitov, R. K.; Kuzma, N. N.; Happer, W.; Driehuys, B.; Merrill, G. F.

    2002-03-01

    The high solubility and large chemical shift of ^129Xe in various tissues makes it an ideal, non-invasive probe for pathological conditions such as cancer or atherosclerosis. To this end, we report NMR measurements of lineshapes, chemical shifts, and relaxation times of ^129Xe dissolved in the following biological tissues in vitro: heart, muscle, sinew, stomach(R.K. Mazitov, K. M. Enikeev, et al., Dokl. Akad. Nauk) 365, 396 (1999)., and the white and yolk of egg. NMR measurements of xenon dissolved in olive and sunflower oils are also reported. Tissues weighing 160--250 mg, not exposed to freezing, were studied in a 11.75 T field at the ^129Xe resonance frequency of 138.4 MHz; the pressure of xenon in the sealed-sample ampoules was ~20 bar. The influence of drugs and water content on tissues was studied. No xenon-water clathrates(J.A. Ripmeester and D.W. Davidson, J. Mol. Struct. ) 75, 67 (1981). were observed in the tissues, even at the high pressures used. The aim of this study is to establish possible correlations between the NMR parameters of dissolved xenon and the state of the tissue.

  6. Iron traps terrestrially derived dissolved organic matter at redox interfaces

    PubMed Central

    Riedel, Thomas; Zak, Dominik; Biester, Harald; Dittmar, Thorsten

    2013-01-01

    Reactive iron and organic carbon are intimately associated in soils and sediments. However, to date, the organic compounds involved are uncharacterized on the molecular level. At redox interfaces in peatlands, where the biogeochemical cycles of iron and dissolved organic matter (DOM) are coupled, this issue can readily be studied. We found that precipitation of iron hydroxides at the oxic surface layer of two rewetted fens removed a large fraction of DOM via coagulation. On aeration of anoxic fen pore waters, >90% of dissolved iron and 27 ± 7% (mean ± SD) of dissolved organic carbon were rapidly (within 24 h) removed. Using ultra-high-resolution MS, we show that vascular plant-derived aromatic and pyrogenic compounds were preferentially retained, whereas the majority of carboxyl-rich aliphatic acids remained in solution. We propose that redox interfaces, which are ubiquitous in marine and terrestrial settings, are selective yet intermediate barriers that limit the flux of land-derived DOM to oceanic waters. PMID:23733946

  7. Sequestration of dissolved CO2 in the Oriskany formation.

    PubMed

    Dilmore, Robert M; Allen, Douglas E; Jones, J Richard McCarthy; Hedges, Sheila W; Soong, Yee

    2008-04-15

    Experiments were conducted to determine the solubility of CO2 in a natural brine solution of the Oriskany formation under elevated temperature and pressure conditions. These data were collected at temperatures of 22 and 75 degrees C and pressures between 100 and 450 bar. Experimentally determined data were compared with CO2 solubility predictions using a model developed by Duan and Sun (Chem. Geol. 2003, 193, 257-271). Model results compare well with Oriskany brine CO2 solubility data collected experimentally, suggesting that the Duan and Sun model is a reliable tool for estimating solution CO2 capacity in high salinity aquifers in the temperature and pressure range evaluated. The capacity for the Oriskany formation to sequester dissolved CO2 was calculated using results of the solubility models, estimation of the density of CO2 saturated brine, and available geographic information system (GIS) information on the formation depth and thickness. Results indicate that the Oriskany formation can hold approximately 0.36 gigatonnes of dissolved CO2 if the full basin is considered. When only the region where supercritical CO2 can exist (temperatures greaterthan 31 degrees C and pressures greaterthan 74 bar) is considered, the capacity of the Oriskany formation to sequester dissolved CO2 is 0.31 gigatonnes. The capacity estimate considering the potential to sequester free-phase supercritical CO2 if brine were displaced from formation pore space is 8.8 gigatonnes in the Oriskany formation. PMID:18497120

  8. Sequestration of Dissolved CO2 in the Oriskany Formation

    SciTech Connect

    Dilmore, R.M.; Allen, D.E.; McCarthy-Jones, J.R.; Hedges, S.W.; Soong, Yee

    2008-04-15

    Experiments were conducted to determine the solubility of CO2 in a natural brine solution of the Oriskany formation under elevated temperature and pressure conditions. These data were collected at temperatures of 22 and 75 °C and pressures between 100 and 450 bar. Experimentally determined data were compared with CO2 solubility predictions using a model developed by Duan and Sun (Chem. Geol. 2003, 193, 257-271). Model results compare well with Oriskany brine CO2 solubility data collected experimentally, suggesting that the Duan and Sun model is a reliable tool for estimating solution CO2 capacity in high salinity aquifers in the temperature and pressure range evaluated. The capacity for the Oriskany formation to sequester dissolved CO2 was calculated using results of the solubility models, estimation of the density of CO2 saturated brine, and available geographic information system (GIS) information on the formation depth and thickness. Results indicate that the Oriskany formation can hold approximately 0.36 gigatonnes of dissolved CO2 if the full basin is considered. When only the region where supercritical CO2 can exist (temperatures greater than 31° C and pressures greater than 74 bar) is considered, the capacity of the Oriskany formation to sequester dissolved CO2 is 0.31 gigatonnes. The capacity estimate considering the potential to sequester free-phase supercritical CO2 if brine were displaced from formation pore space is 8.8 gigatonnes in the Oriskany formation.

  9. FDA-Approved Natural Polymers for Fast Dissolving Tablets.

    PubMed

    Alam, Md Tausif; Parvez, Nayyar; Sharma, Pramod Kumar

    2014-01-01

    Oral route is the most preferred route for administration of different drugs because it is regarded as safest, most convenient, and economical route. Fast disintegrating tablets are very popular nowadays as they get dissolved or facilely disintegrated in mouth within few seconds of administration without the need of water. The disadvantages of conventional dosage form, especially dysphagia (arduousness in swallowing), in pediatric and geriatric patients have been overcome by fast dissolving tablets. Natural materials have advantages over synthetic ones since they are chemically inert, non-toxic, less expensive, biodegradable and widely available. Natural polymers like locust bean gum, banana powder, mango peel pectin, Mangifera indica gum, and Hibiscus rosa-sinenses mucilage ameliorate the properties of tablet and utilized as binder, diluent, and superdisintegrants increase the solubility of poorly water soluble drug, decrease the disintegration time, and provide nutritional supplement. Natural polymers are obtained from the natural origin and they are cost efficacious, nontoxic, biodegradable, eco-friendly, devoid of any side effect, renewable, and provide nutritional supplement. It is proved from the studies that natural polymers are more safe and efficacious than the synthetic polymers. The aim of the present article is to study the FDA-approved natural polymers utilized in fast dissolving tablets. PMID:26556207

  10. FDA-Approved Natural Polymers for Fast Dissolving Tablets

    PubMed Central

    Alam, Md Tausif; Parvez, Nayyar; Sharma, Pramod Kumar

    2014-01-01

    Oral route is the most preferred route for administration of different drugs because it is regarded as safest, most convenient, and economical route. Fast disintegrating tablets are very popular nowadays as they get dissolved or facilely disintegrated in mouth within few seconds of administration without the need of water. The disadvantages of conventional dosage form, especially dysphagia (arduousness in swallowing), in pediatric and geriatric patients have been overcome by fast dissolving tablets. Natural materials have advantages over synthetic ones since they are chemically inert, non-toxic, less expensive, biodegradable and widely available. Natural polymers like locust bean gum, banana powder, mango peel pectin, Mangifera indica gum, and Hibiscus rosa-sinenses mucilage ameliorate the properties of tablet and utilized as binder, diluent, and superdisintegrants increase the solubility of poorly water soluble drug, decrease the disintegration time, and provide nutritional supplement. Natural polymers are obtained from the natural origin and they are cost efficacious, nontoxic, biodegradable, eco-friendly, devoid of any side effect, renewable, and provide nutritional supplement. It is proved from the studies that natural polymers are more safe and efficacious than the synthetic polymers. The aim of the present article is to study the FDA-approved natural polymers utilized in fast dissolving tablets. PMID:26556207

  11. Iron traps terrestrially derived dissolved organic matter at redox interfaces.

    PubMed

    Riedel, Thomas; Zak, Dominik; Biester, Harald; Dittmar, Thorsten

    2013-06-18

    Reactive iron and organic carbon are intimately associated in soils and sediments. However, to date, the organic compounds involved are uncharacterized on the molecular level. At redox interfaces in peatlands, where the biogeochemical cycles of iron and dissolved organic matter (DOM) are coupled, this issue can readily be studied. We found that precipitation of iron hydroxides at the oxic surface layer of two rewetted fens removed a large fraction of DOM via coagulation. On aeration of anoxic fen pore waters, >90% of dissolved iron and 27 ± 7% (mean ± SD) of dissolved organic carbon were rapidly (within 24 h) removed. Using ultra-high-resolution MS, we show that vascular plant-derived aromatic and pyrogenic compounds were preferentially retained, whereas the majority of carboxyl-rich aliphatic acids remained in solution. We propose that redox interfaces, which are ubiquitous in marine and terrestrial settings, are selective yet intermediate barriers that limit the flux of land-derived DOM to oceanic waters. PMID:23733946

  12. Use of Passive Samplers to Measure Dissolved Organic Contaminants in a Temperate Estuary

    EPA Science Inventory

    Measuring dissolved concentrations of organic contaminants can be challenging given their low solubilities and high particle association. However, to perform accurate risk assessments of these chemicals, knowing the dissolved concentration is critical since it is considered to b...

  13. STREAM PRODUCTIVITY ANALYSIS WITH DORM (DISSOLVED OXYGEN ROUTING MODEL) - 2: PARAMETER ESTIMATION AND SENSITIVITY

    EPA Science Inventory

    The dissolved oxygen routing model DORM, which determines productivity and respiration of a stream biological community, requires in addition to stream geometry and stream flow, parameter values for reaeration coefficients and temperature and dissolved oxygen (DO) limitations on ...

  14. THE ROLE OF NITROGEN IN CHROMOPHORIC AND FLUORESCENT DISSOLVED ORGANIC MATTER FORMATION

    EPA Science Inventory

    Microbial and photochemical processes affect chromophoric dissolved organic matter (CDOM) dynamics in the ocean. Some evidence suggests that dissolved nitrogen plays a role in CDOM formation, although this has received little systematic attention in marine ecosystems. Coastal sea...

  15. Dissolved Nutrient Retention Dynamics in River Networks: A Modeling Investigation of Transient Flow and Scale Effects

    SciTech Connect

    Ye, Sheng; Covino, Timothy P.; Sivapalan, Murugesu; Basu, Nandita; Li, Hongyi; Wang, Shaowen

    2012-06-30

    In this paper, we use a dynamic network flow model, coupled with a transient storage zone biogeochemical model, to simulate dissolved nutrient removal processes at the channel network scale. We have explored several scenarios in respect of the combination of rainfall variability, and the biological and geomorphic characteristics of the catchment, to understand the dominant controls on removal and delivery of dissolved nutrients (e.g., nitrate). These model-based theoretical analyses suggested that while nutrient removal efficiency is lower during flood events compared to during baseflow periods, flood events contribute significantly to bulk nutrient removal, whereas bulk removal during baseflow periods is less. This is due to the fact that nutrient supply is larger during flood events; this trend is even stronger in large rivers. However, the efficiency of removal during both periods decreases in larger rivers, however, due to (i) increasing flow velocities and thus decreasing residence time, and (ii) increasing flow depth, and thus decreasing nutrient uptake rates. Besides nutrient removal processes can be divided into two parts: in the main channel and in the hyporheic transient storage zone. When assessing their relative contributions the size of the transient storage zone is a dominant control, followed by uptake rates in the main channel and in the transient storage zone. Increasing size of the transient storage zone with downstream distance affects the relative contributions to nutrient removal of the water column and the transient storage zone, which also impacts the way nutrient removal rates scale with increasing size of rivers. Intra-annual hydrologic variability has a significant impact on removal rates at all scales: the more variable the streamflow is, compared to mean discharge, the less nutrient is removed in the channel network. A scale-independent first order uptake coefficient, ke, estimated from model simulations, is highly dependent on the

  16. Variable C : N : P stoichiometry of dissolved organic matter cycling in the Community Earth System Model

    DOE PAGESBeta

    Letscher, R. T.; Moore, J. K.; Teng, Y. -C.; Primeau, F.

    2014-06-16

    Dissolved organic matter (DOM) plays an important role in the ocean's biological carbon pump by providing an advective/mixing pathway for ~ 20% of export production. DOM is known to have a stoichiometry depleted in nitrogen (N) and phosphorus (P) compared to the particulate organic matter pool, a~fact that is often omitted from biogeochemical-ocean general circulation models. However the variable C : N : P stoichiometry of DOM becomes important when quantifying carbon export from the upper ocean and linking the nutrient cycles of N and P with that of carbon. Here we utilize recent advances in DOM observational data coveragemore » and offline tracer-modeling techniques to objectively constrain the variable production and remineralization rates of the DOM C / N / P pools in a simple biogeochemical-ocean model of DOM cycling. The optimized DOM cycling parameters are then incorporated within the Biogeochemical Elemental Cycling (BEC) component of the Community Earth System Model and validated against the compilation of marine DOM observations. The optimized BEC simulation including variable DOM C : N : P cycling was found to better reproduce the observed DOM spatial gradients than simulations that used the canonical Redfield ratio. Global annual average export of dissolved organic C, N, and P below 100 m was found to be 2.28 Pg C yr-1 (143 Tmol C yr-1), 16.4 Tmol N yr-1, and 1 Tmol P yr-1, respectively with an average export C : N : P stoichiometry of 225 : 19 : 1 for the semilabile (degradable) DOM pool. DOC export contributed ~ 25% of the combined organic C export to depths greater than 100 m.« less

  17. Temporal variations in dissolved selenium in Lake Kinneret (Israel)

    USGS Publications Warehouse

    Nishri, A.; Brenner, I.B.; Hall, G.E.M.; Taylor, H.E.

    1999-01-01

    Selenium is an essential micronutrient for the growth of the dinoflagellate Peridinium gatunense that dominates the spring algal bloom in Lake Kinneret (LK). The relationship between the levels of dissolved selenium species and the occurance of algal blooms in this lake was studied. During algal blooms of P. gatunense in spring and of the blue-green Aphanizomenon ovalisporum in fall (in 1994) the concentration of epilimnetic dissolved organic Se (Se(org)) increased whereas that of selenite (SeIV) decreased, to levels below the limit of detection: 5 ng/l. The disappearance of SeIV during these blooms is attributed to algal uptake and it is suggested that the growth of both algae may have depended on Se(org) regeneration. A budget performed for selenate (SeVI) suggests that this species is also consumed by algae but to a lesser extent than SeIV (in 1994 ~40% of the epilimnetic load). During the stratification period the hypolimnion of Lake Kinneret becomes anoxic, with high levels of dissolved sulfide. The affects of this environment on the distribution of Se oxy-anions, selenite (SeIV) and selenate(SeVI), were also studied. At the onset of thermal stratification (March) about 35% of the lake inventory of both Se oxidized species are entrapped in the hypolimnion. During stages of oxygen depletion and H2S accumulation, SeIV is completely and SeVI partially removed from this layer. The removal is attributed to reduction followed by formation of particulate reduced products, such as elemental selenium Se(o). The ratio between SeVI to total dissolved selenium (SE(T)) in water sources to the lake is ~0.84, about twice the corresponding ratio in the lake (~0.44, during holomixis). In the lake about 75% of annual SeVI inflow from external sources undergoes reduction to selenide (Se-II) and Se(o) through epilimnetic algal assimilation and hypolimnetic anoxic reduction, respectively. It is suggested that the latter oxidation of the dissolved organic selenide released from

  18. Removal of hydrocarbons from petrochemical wastewater by dissolved air flotation.

    PubMed

    Galil, N I; Wolf, D

    2001-01-01

    The dissolved air flotation (DAF) method has an important role in the removal of hydrocarbons, as well as in the protection of the biological treatment, which usually follows the DAF. The aims of this study were to evaluate the removal efficiencies of suspended solids, general organic matter, hydrocarbons and phenols by DAF, as influenced by the flocculant type, aluminum sulfate (alum) or a cationic polyelectrolyte. Laboratory batch experiments included chemical flocculation followed by DAF, controlling the flocculant dose and the air to solids ratio. The characterization of the influent and effluent was based on general analysis of organic matter (COD), suspended solids, hydrocarbons and phenols. The influent to all experiments was supplied daily from the outlet of a full scale oil-water gravitational separation unit at a petrochemical complex in Haifa, Israel. The influent contained hydrocarbons in the range of 20 to 77 mg/L. Usually less than 10% were found in "free" form, 70 to 80% were emulsified and 10 to 20% were dissolved. The DAF process enabled us to reduce the general hydrocarbon content by 50 to 90%. The effluent was characterized by stable and uniform levels of suspended solids, and oil, almost without depending on the influent concentrations. The results indicate that the chemical flocculation followed by DAF removed efficiently the emulsified phase, which could be aggregated and separated to the surface. However, it was found that the process could also remove substantial amounts of dissolved organic matter. This mechanism could be explained by the hydrophobic characteristics of some of the substances, which could bind to the solid surfaces. It was found that aggregates created by the flocculation with the cationic polyelectrolite (C-577) could remove up to 40% from the dissolved hydrocarbon. Alum flocs also indicated removal of soluble materials, mainly phenols. The results obtained in this study indicated the possibility to improve the protection

  19. Trophic complexity in aqueous systems: bacterial species richness and protistan predation regulate dissolved organic carbon and dissolved total nitrogen removal.

    PubMed

    Saleem, Muhammad; Fetzer, Ingo; Harms, Hauke; Chatzinotas, Antonis

    2016-02-24

    Loading of water bodies with dissolved organic carbon (DOC) and dissolved total nitrogen (DTN) affects their integrity and functioning. Microbial interactions mitigate the negative effects of high nutrient loads in these ecosystems. Despite numerous studies on how biodiversity mediates ecosystem functions, whether and how diversity and complexity of microbial food webs (horizontal, vertical) and the underlying ecological mechanisms influence nutrient removal has barely been investigated. Using microbial microcosms accommodating systematic combinations of prey (bacteria) and predator (protists) species, we showed that increasing bacterial richness improved the extent and reliability of DOC and DTN removal. Bacterial diversity drove nutrient removal either due to species foraging physiology or functional redundancy, whereas protistan diversity affected nutrient removal through bacterial prey resource partitioning and changing nutrient balance in the system. Our results demonstrate that prey-predator diversity and trophic interactions interactively determine nutrient contents, thus implying the vital role of microbial trophic complexity as a biological buffer against DOC and DTN. PMID:26888033

  20. Fiber-optic dissolved oxygen and dissolved carbon dioxide sensors using fluorophores encapsulated in sol gel matrices

    NASA Astrophysics Data System (ADS)

    Kwon, Hyeog-Chan

    Fiber optic chemical sensors (FOCS) for oxygen, dissolved oxygen (DO), and dissolved CO2 sensing using thin films of fluorophores encapsulated in sol-gel matrices were made and tested. The DO/O2 sensor used ruthenium(II) tris(4,7-diphenyl-1,10-phenanthroline) perchlorate (Ru(Ph 2Phen)Cl2) as the oxygen sensitive fluorophore and methyltrimethoxysilane (MTMS) sol-gel as the encapsulating matrix material. For the DCO2 sensor, 8-hydroxy-1,3,6-pyrenetrisulfonic acid trisodium salt (HPTS) co-doped with sodium bicarbonate was used as the DCO2 sensitive fluorophore-chemical system and diisobutoxy-alumino triethoxysilane (ASE) sol-gel was used as the encapsulating matrix material. It was found that oxygen quenches the excited state Ru(Ph2Phen)Cl 2 by diffusing through the MTMS matrix. Continuous excitation of Ru(Ph 2Phen)Cl2 during MTMS drying resulted in long, single exponential lifetimes of the metal complex and increased sensor sensitivity. When the sensor was field tested, it was found to have an excellent match compared to conventional titration method for determining dissolved oxygen concentrations and had fast response times. It was determined that this sensor measured the vapor pressure of oxygen rather than the absolute concentration of dissolved oxygen. For DCO2 sensing, it was found that the dynamic response of the senor could be tuned by varying the HPTS to NaHCO3 ratios. The sensor had fast response times compared to other fiber optic DCO 2 sensors reported which typically have response times of minutes.

  1. Dissolved Carbonate Species in Mixed-Volatile Rhyolitic melts: Carbon Speciation Correlates with Dissolved H2O Content

    NASA Astrophysics Data System (ADS)

    Moore, G.; Roggensack, K.; Holloway, J.

    2006-12-01

    The solubility and speciation of volatiles (H2O, CO2) in silicate melts play an important role in determining magma behavior and properties (e.g. volcanic degassing, viscosity, density, glass transition temperature). Carbon dioxide is an important volatile component to consider because of its abundance in volcanic systems, its potential effect on melt behavior, and its low solubility (relative to H2O) that makes it the primary bubble former at high pressures. In previous volatile solubility and spectroscopic work, carbon dioxide has been observed to dissolve as a molecular CO2 unit in silicic melts (e.g. Blank and Holloway, 1994; Tamic et al, 2001), as a carbonate ion in mafic melts (Fine and Stolper, 1986), while intermediate magma compositions such as andesites contain both species (King et al, 2002). FTIR spectroscopic results from low pressure (400- 600 MPa) piston-cylinder experiments show that a calc-alkaline rhyolite melt saturated with a mixed (H2O + CO2) fluid of known composition, has both molecular CO2 and carbonate species present. Dissolved carbonate is not observed in glasses with less than ~2.5 wt% H2O, but its abundance increases linearly with increasing water content thereafter to ~80% carbonate (relative to total dissolved CO2) at ~6 wt% H2O. These results are consistent with H2O depolymerizing the rhyolite (i.e. making it more basalt-like), thereby favoring the formation of the carbonate species. We speculate that the reasons previous mixed volatile studies on rhyolites (e.g. Tamic et al, 2001; Liu et al, 2004) have not observed dissolved carbonate may include bulk compositional differences (i.e. more or less network modifiers present), different P-T conditions, and/or differing quench rates for the experimental apparatus used. These observations have significant implications for understanding the processes occuring during volatile degassing of explosive rhyolitic volcanic systems that contain both H2O and CO2.

  2. 40 CFR 430.40 - Applicability; description of the dissolving sulfite subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... dissolving sulfite subcategory. 430.40 Section 430.40 Protection of Environment ENVIRONMENTAL PROTECTION... SOURCE CATEGORY Dissolving Sulfite Subcategory § 430.40 Applicability; description of the dissolving sulfite subcategory. The provisions of this subpart are applicable to discharges resulting from...

  3. 40 CFR 430.40 - Applicability; description of the dissolving sulfite subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... dissolving sulfite subcategory. 430.40 Section 430.40 Protection of Environment ENVIRONMENTAL PROTECTION... SOURCE CATEGORY Dissolving Sulfite Subcategory § 430.40 Applicability; description of the dissolving sulfite subcategory. The provisions of this subpart are applicable to discharges resulting from...

  4. 40 CFR 430.40 - Applicability; description of the dissolving sulfite subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... dissolving sulfite subcategory. 430.40 Section 430.40 Protection of Environment ENVIRONMENTAL PROTECTION... SOURCE CATEGORY Dissolving Sulfite Subcategory § 430.40 Applicability; description of the dissolving sulfite subcategory. The provisions of this subpart are applicable to discharges resulting from...

  5. Biochemical Oxygen Demand and Dissolved Oxygen. Training Module 5.105.2.77.

    ERIC Educational Resources Information Center

    Kirkwood Community Coll., Cedar Rapids, IA.

    This document is an instructional module package prepared in objective form for use by an instructor familiar with the azide modification of the Winkler dissolved oxygen test and the electronic dissolved oxygen meter test procedures for determining the dissolved oxygen and the biochemical oxygen demand of a wastewater sample. Included are…

  6. Dissolved oxygen imaging in a porous medium to investigate biodegradation in a plume with limited electron acceptor supply.

    PubMed

    Huang, Wei E; Oswald, Sascha E; Lerner, David N; Smith, Colin C; Zheng, Chunmiao

    2003-05-01

    A novel combination of noninvasive imaging with an oxygen sensitive fluorescent indicator was developed to investigate the biodegradation processes occurring at the fringe of a solute plume, where the supply of oxygen was limited. A thin transparent porous matrix (156 x 120 x 3 mm) was made from quartz plates and quartz sand (212-300 microm) and enriched with acetate-degrading bacteria. A degrading plume developed from a continuous acetate source in the uniform flow field containing dissolved oxygen. Ruthenium (II)-dichlorotris(1,10-phenanthroline) (Ru(phen)3Cl2), a water-soluble fluorescent dye, was used as an indicator of dissolved oxygen. The fluorescence intensity was dependent on the concentration of oxygen because the dissolved oxygen acted as collisional quencher. The oxygen distribution was interpreted from images recorded by a CCD camera. These two-dimensional experimental results showed quantitatively how the oxygen concentrations decreased strongly at the narrow plume fringe and that oxygen was depleted at the core of the plume. Separately, dispersivity was measured in a series of nonreactive transport experiments, and biodegradation parameters were evaluated by batch experiments. Two-dimensional numerical simulations with MT3D/RT3D used these parameters, and the predicted oxygen distributions were compared with the experimental results. This measurement method provides a novel approach to investigate details of solute transport and biodegradation in porous media. PMID:12775064

  7. Dissolved Organic Matter Transformations: Implications for Catchment-Scale Processes

    NASA Astrophysics Data System (ADS)

    Robinson, A.; Hernes, P.; Montanez, I.; Eustis, B.

    2006-12-01

    Particulate and dissolved phase lignin parameters are used to understand sources and dynamics of terrigenous organic matter (OM) in freshwater and marine systems. Impacts of catchment properties, such as soil type and mineralogy, vegetation distribution and hydrologic conditions on terrestrial dissolved and particulate biomarker compositions have not been addressed. Our experimental approach deciphers relative contributions of these parameters on bulk DOM compositions. Carbon-normalized lignin yields (Λ8) are one means to assess contributions of lignin phenols to bulk organic carbon. Ratios of syringyl (S), vanillyl (V) and cinnamyl (C) lignin phenols distinguish angiosperm and gymnosperm woody and nonwoody tissues. Ratios of acids:aldehydes (ad:ac) within vanillyl groups indicate diagenetic alteration of OM. Interpretation of these ratios relies on the fundamental assumption that each lignin compound behaves similarly, despite differences in solubility and sorption. Fractionation due to leaching impacts C:V, ac:al and (Λ8). C:V ranges from 1/2 to 4 times original plant compositions, increasing proportions of DOM ascribed to nonwoody tissues. Shifts in C:V and S:V due to leaching, suggest that source ratios from plant materials may not be appropriate endmembers for dissolved phases. An ~2-fold increase in ac:al ratios between litters and leachates suggest that dissolved phases are more diagenetically altered than litters, although this is simply due to solubilization. Λ8 values, tracking lignin and bulk carbon solubility differences, indicate greater loss of bulk OM relative to lignin for most plant litters. During sorption of leachates to mineral soils, lignin compositional trends are more variable compared to leaching data. Sorption of angiosperm leachates resulted in significant enrichment of S phenols on soils, which would increase the inferred contribution of angiosperms obtained for mixtures. C:V fractionation during sorption decreased in 3 of 4 plant

  8. Occurrence and distribution of dissolved tellurium in Changjiang River estuary

    NASA Astrophysics Data System (ADS)

    Wu, Xiaodan; Song, Jinming; Li, Xuegang

    2014-03-01

    With the implementation of the GEOTRACES program, the biogeochemical cycle and distribution of tellurium (Te) in marine environments are becoming increasing environmental concerns. In this study, the concentration of dissolved Te in the Changjiang (Yangtze) River estuary and nearby waters was determined in May 2009 by hydride-generation atomic fluorescence spectrometry to elucidate the abundance, dominant species, distribution, and relationship with environmental factors. Results show that: (1) dissolved Te was low owing to its low abundance in the Earth's crust, high insolubility in water, and strong affinity to particulate matter; (2) Te(IV) and Te(VI) predominated in surface water. Te(VI) was the dominant species in bottom water, and Te(IV) was the minor species; (3) Horizontally, resulting from low phytoplankton metabolism and the weak reduction from Te(VI) to Te(IV) in the shore, Te(IV) was concentrated in the central zone instead of the coastal region. However, Te(VI) was abundant near the mouth of the Changjiang River where the Changjiang water is diluted and in the area to the south where the Taiwan Warm Current invaded. In the adsorption-desorption process, Te(IV) was negatively related to suspended particulate matter (SPM), indicating that it was adsorbed by particulate matter. While for Te(VI), the positive correlation with SPM suggested that it was desorbed from the solid phase. In the estuary, dissolved Te had a negative correlation to salinity. However, it deviated from the dilution line in high-salinity regions due to the invasion of the Taiwan Warm Current and the mineralization of organic matter. The relationship between Te(IV) and SPM nutrients indicated that it was more bioavailable and more related to phosphorus than to nitrogen. Progress in the field is slow and more research is needed to quantify the input of Te to the estuary and evaluate the biochemical role of organisms.

  9. Metabolomics confirms that dissolved organic carbon mitigates copper toxicity.

    PubMed

    Taylor, Nadine S; Kirwan, Jennifer A; Yan, Norman D; Viant, Mark R; Gunn, John M; McGeer, James C

    2016-03-01

    Reductions in atmospheric emissions from the metal smelters in Sudbury, Canada, produced major improvements in acid and metal contamination of local lakes and indirectly increased dissolved organic carbon (DOC) concentrations. Metal toxicity, however, has remained a persistent problem for aquatic biota. Integrating high-throughput, nontargeted mass spectrometry metabolomics with conventional toxicological measures elucidated the mediating effects of dissolved organic matter (DOM) on the toxicity of Cu to Daphnia pulex-pulicaria, a hybrid isolated from these soft water lakes. Two generations of daphniids were exposed to Cu (0-20 μg/L) at increasing levels of natural DOM (0-4 mg DOC/L). Added DOM reduced Cu toxicity monotonically with median lethal concentration values increasing from 2.3 μg/L Cu without DOM to 22.7 μg/L Cu at 4 mg DOC/L. Reproductive output similarly benefited, increasing with DOM, yet falling with increases in Cu. Second generation reproduction was more impaired than the first generation. Dissolved organic matter had a greater influence than Cu on the metabolic status of the daphniids. Putative identification of metabolite peaks indicated that DOM elevation increased the metabolic energy status of the first generation animals, but this benefit was reduced in the second generation, although evidence of increased oxidative stress was detected. These results indicate that Sudbury's terrestrial ecosystems should be managed to increase aquatic DOM supply to enable daphniid colonists to both survive and foster stable populations. Environ Toxicol Chem 2016;35:635-644. © 2015 SETAC. PMID:26274843

  10. Chemical shift of hyperpolarized 129Xe dissolved in liquid nitrogen

    NASA Astrophysics Data System (ADS)

    Patton, B.; Kuzma, N. N.; Happer, W.

    2002-01-01

    We report NMR measurements of hyperpolarized xenon dissolved in liquid nitrogen. The dependence of the 129Xe frequency shift on liquid nitrogen temperature was measured along the nitrogen saturated vapor curve from 77 to 93 K. Plotted as a function of the liquid nitrogen density, the chemical shift of xenon is very well described by a simple proportionality relation, with a slope of 0.2135(15) ppm/amagat. The relationship between the chemical shift and the longitudinal spin relaxation is considered in terms of the spin-rotation interaction, and estimates of Xe relaxation time in liquid nitrogen are discussed.

  11. Bead and Process for Removing Dissolved Metal Contaminants

    SciTech Connect

    Summers, Bobby L., Jr.; Bennett, Karen L.; Foster, Scott A.

    2005-01-18

    A bead is provided which comprises or consists essentially of activated carbon immobilized by crosslinked poly (carboxylic acid) binder, sodium silicate binder, or polyamine binder. The bead is effective to remove metal and other ionic contaminants from dilute aqueous solutions. A method of making metal-ion sorbing beads is provided, comprising combining activated carbon, and binder solution (preferably in a pin mixer where it is whipped), forming wet beads, and heating and drying the beads. The binder solution is preferably poly(acrylic acid) and glycerol dissolved in water and the wet beads formed from such binder solution are preferably heated and crosslinked in a convection oven.

  12. Continuous measurement of dissolved sulfide in sewer systems.

    PubMed

    Sutherland-Stacey, L; Corrie, S; Neethling, A; Johnson, I; Gutierrez, O; Dexter, R; Yuan, Z; Keller, J; Hamilton, G

    2008-01-01

    Sulfides are particularly problematic in the sewage industry. Hydrogen sulfide causes corrosion of concrete infrastructure, is dangerous at high concentrations and is foul smelling at low concentrations. Despite the importance of sulfide monitoring there is no commercially available system to quantify sulfide in waste water. In this article we report on our use of an in situ spectrometer to quantify bisulfide in waste water and additional analysis with a pH probe to calculate total dissolved sulfide. Our results show it is possible to use existing commercially available and field proven sensors to measure sulfide to mg/l levels continuously with little operator intervention and no sample preparation. PMID:18309215

  13. Toxicity of dissolved ozone to fish eggs and larvae

    SciTech Connect

    Asbury, C.; Coler, R.

    1980-07-01

    To find levels of dissolved residual ozone lethal to fish eggs and larvae during brief exposures, continuous-flow toxicity tests were performed with eggs and larvae of yellow perch (Perca flavescens), and fathead minnow (Pimephales promelas), eggs of white sucker (Catastomus commersoni), and larvae of bluegill sunfish (Lepomis macrochirus). The 50 and 99% lethal concentrations with confidence limits were calculated. Eggs of the species tested were more tolerant than larvae, which were destroyed by very brief exposures (less than 2 minutes) to residuals less than 0.1 mg/1. Because of the sensitivity of the larvae, residual ozone concentrations in natural waters should remain well below 50 ..mu..g/1.

  14. Catchment scale molecular composition of hydrologically mobilized dissolved organic matter

    NASA Astrophysics Data System (ADS)

    Raeke, Julia; Lechtenfeld, Oliver J.; Oosterwoud, Marieke R.; Bornmann, Katrin; Tittel, Jörg; Reemtsma, Thorsten

    2016-04-01

    Increasing concentrations of dissolved organic matter (DOM) in rivers of temperate catchments in Europe and North Amerika impose new technical challenges for drinking water production. The driving factors for this decadal increase in DOM concentration are not conclusive and changes in annual temperatures, precipitation and atmospheric deposition are intensely discussed. It is known that the majority of DOM is released by few but large hydrologic events, mobilizing DOM from riparian wetlands for export by rivers and streams. The mechanisms of this mobilization and the resulting molecular composition of the released DOM may be used to infer long-term changes in the biogeochemistry of the respective catchment. Event-based samples collected over two years from streams in three temperate catchments in the German mid-range mountains were analyzed after solid-phase extraction of DOM for their molecular composition by ultra-high resolution mass spectrometry (FT-ICR MS). Hydrologic conditions, land use and water chemistry parameters were used to complement the molecular analysis. The molecular composition of the riverine DOM was strongly dependent on the magnitude of the hydrologic events, with unsaturated, oxygen-enriched compounds being preferentially mobilized by large events. This pattern is consistent with an increase in dissolved iron and aluminum concentrations. In contrast, the relative proportions of nitrogen and sulfur bearing compounds increased with an increased agricultural land use but were less affected by the mobilization events. Co-precipitation experiments with colloidal aluminum showed that unsaturated and oxygen-rich compounds are preferentially removed from the dissolved phase. The precipitated compounds thus had similar chemical characteristics as compared to the mobilized DOM from heavy rain events. Radiocarbon analyses also indicated that this precipitated fraction of DOM was of comparably young radiocarbon age. DOM radiocarbon from field samples

  15. Oxidation of nanoscale zero-valent iron under sufficient and limited dissolved oxygen: Influences on aggregation behaviors.

    PubMed

    Jiang, Danlie; Hu, Xialin; Wang, Rui; Yin, Daqiang

    2015-03-01

    Oxidations of nanoscale zero-valent iron (nZVI) under aerobic (dissolved oxygen≈8mgL(-1)) and anaerobic (dissolved oxygen <3mgL(-1)) conditions were simulated, and their influences on aggregation behaviors of nZVI were investigated. The two oxidation products were noted as HO-nZVI (nZVI oxidized in highly oxygenated water) and LO-nZVI (nZVI oxidized in lowly oxygenated water) respectively. The metallic iron of the oxidized nZVI was almost exhausted (Fe(0)≈8±5%), thus magnetization mainly depended on magnetite content. Since sufficient dissolved oxygen led to the much less magnetite (∼15%) in HO-nZVI than that in LO-nZVI (>90%), HO-nZVI was far less magnetic (Ms=88kAm(-1)) than LO-nZVI (Ms=365kAm(-1)). Consequently, HO-nZVI formed small agglomerates (228±10nm), while LO-nZVI tended to form chain-like aggregations (>1μm) which precipitated rapidly. Based on the EDLVO theory, we suggested that dissolved oxygen level determined aggregation morphologies by controlling the degree of oxidation and the magnitude of magnetization. Then the chain-like alignment of LO-nZVI would promote further aggregation, but the agglomerate morphology of HO-nZVI would eliminate magnetic forces and inhibit the aggregation while HO-nZVI remained magnetic. Our results indicated the fine colloidal stability of HO-nZVI, which might lead to the great mobility in the environment. PMID:25441925

  16. Process for coal liquefaction by separation of entrained gases from slurry exiting staged dissolvers

    DOEpatents

    Givens, Edwin N.; Ying, David H. S.

    1983-01-01

    There is described an improved liquefaction process by which coal is converted to a low ash and low sulfur carbonaceous material that can be used as a fuel in an environmentally acceptable manner without costly gas scrubbing equipment. In the process, coal is slurried with a solvent, passed through a preheater and at least two dissolvers in series in the presence of hydrogen-rich gases at elevated temperatures and pressures. Solids, including mineral ash and unconverted coal macerals are separated from the condensed dissolver effluent. In accordance with the improved process, fresh hydrogen is fed to each dissolver and the entrained gas from each dissolver is separated from the slurry phase and removed from the reactor system before the condensed phase is passed to the next dissolver in the series. In accordance with another process, the feeds to the dissolvers are such that the top of each downstream dissolver is used as a gas-liquid separator.

  17. Process performance of the pilot-scale in situ vitrification of a simulated waste disposal site at the Oak Ridge National Laboratory

    SciTech Connect

    Carter, J.G.; Koegler, S.S.; Bates, S.O.

    1988-06-01

    Process feasibility studies have been successfully performed on three developmental scales to determine the potential for applying in situ vitrification to intermediate-level (low-level) waste placed in seepage pits and trenches at Oak Ridge National Laboratory (ORNL). In the laboratory, testing was performed in crucibles containing a mixture of 50% ORNL soil and 50% limestone. In an engineering-scale test at Pacific Northwest Laboratory a /1/12/-scale simulation of an ORNL waste trench was constructed and vitrified, resulting in a waste product containing soil and limestone concentrations of 68 wt % and 32 wt %, respectively. In the pilot-scale test a /3/8/-scale simulation of the same trench was constructed and vitrified at ORNL, resulting in soil and limestone concentrations of 80% and 20%, respectively, in the waste product. Results of the three scales of testing indicate that the ORNL intermediate-level (low-level) waste sites can be successfully processed by in situ vitrification; the waste form will retain significant quantities of the cesium and strontium. Because cesium-137 and strontium-90 are the major components of the radionuclide inventory in the ORNL seepage pits and trenches, final field process decontamination factors (i.e., losses to the off-gas system relative to the waste inventory) of 1.0 E + 4 are desired to minimize activity buildup in the off-gas system. 17 refs., 34 figs., 13 tabs.

  18. INFLUENCE OF PH, DISSOLVED OXYGEN, SUSPENDED SOLIDS OR DISSOLVED SOLIDS UPON VENTILATORY AND COUGH FREQUENCIES IN THE BLUEGILL 'LEPOMIS MACROCHIRUS' AND BROOK TROUT 'SALVELINUS FONTINALIS'

    EPA Science Inventory

    Conservative no-effect concentration ranges were estimated for ventilatory and coughing responses of bluegill sunfish Lepomis macrochirus and brook trout Salvelinus fontinalis exposed to altered pH, or to changes in dissolved oxygen (DO), suspended solids, or dissolved solids con...

  19. Dynamics of dissolved organic matter in fjord ecosystems: Contributions of terrestrial dissolved organic matter in the deep layer

    NASA Astrophysics Data System (ADS)

    Yamashita, Youhei; McCallister, S. Leigh; Koch, Boris P.; Gonsior, Michael; Jaffé, Rudolf

    2015-06-01

    Annually, rivers and inland water systems deliver a significant amount of terrestrial organic matter (OM) to the adjacent coastal ocean in both particulate and dissolved forms; however, the metabolic and biogeochemical transformations of OM during its seaward transport remains one of the least understood components of the global carbon cycle. This transfer of terrestrial carbon to marine ecosystems is crucial in maintaining trophic dynamics in coastal areas and critical in global carbon cycling. Although coastal regions have been proposed as important sinks for exported terrestrial materials, most of the global carbon cycling data, have not included fjords in their budgets. Here we present distributional patterns on the quantity and quality of dissolved OM in Fiordland National Park, New Zealand. Specifically, we describe carbon dynamics under diverse environmental settings based on dissolved organic carbon (DOC) depth profiles, oxygen concentrations, optical properties (fluorescence) and stable carbon isotopes. We illustrate a distinct change in the character of DOC in deep waters compared to surface and mid-depth waters. Our results suggest that, both, microbial reworking of terrestrially derived plant detritus and subsequent desorption of DOC from its particulate counterpart (as verified in a desorption experiment) are the main sources of the humic-like enriched DOC in the deep basins of the studied fjords. While it has been suggested that short transit times and protection of OM by mineral sorption may ultimately result in significant terrestrial carbon burial and preservation in fjords, our data suggests the existence of an additional source of terrestrial OM in the form of DOC generated in deep, fjord water.

  20. Global effects of agriculture on fluvial dissolved organic matter

    PubMed Central

    Graeber, Daniel; Boëchat, Iola G.; Encina-Montoya, Francisco; Esse, Carlos; Gelbrecht, Jörg; Goyenola, Guillermo; Gücker, Björn; Heinz, Marlen; Kronvang, Brian; Meerhoff, Mariana; Nimptsch, Jorge; Pusch, Martin T.; Silva, Ricky C. S.; von Schiller, Daniel; Zwirnmann, Elke

    2015-01-01

    Agricultural land covers approximately 40% of Earth’s land surface and affects hydromorphological, biogeochemical and ecological characteristics of fluvial networks. In the northern temperate region, agriculture also strongly affects the amount and molecular composition of dissolved organic matter (DOM), which constitutes the main vector of carbon transport from soils to fluvial networks and to the sea, and is involved in a large variety of biogeochemical processes. Here, we provide first evidence about the wider occurrence of agricultural impacts on the concentration and composition of fluvial DOM across climate zones of the northern and southern hemispheres. Both extensive and intensive farming altered fluvial DOM towards a more microbial and less plant-derived composition. Moreover, intensive farming significantly increased dissolved organic nitrogen (DON) concentrations. The DOM composition change and DON concentration increase differed among climate zones and could be related to the intensity of current and historical nitrogen fertilizer use. As a result of agriculture intensification, increased DON concentrations and a more microbial-like DOM composition likely will enhance the reactivity of catchment DOM emissions, thereby fuelling the biogeochemical processing in fluvial networks, and resulting in higher ecosystem productivity and CO2 outgassing. PMID:26541809

  1. Rapid implantation of dissolving microneedles on an electrospun pillar array.

    PubMed

    Yang, Huisuk; Kim, Soyoung; Huh, Inyoung; Kim, Suyong; Lahiji, Shayan F; Kim, Miroo; Jung, Hyungil

    2015-09-01

    Dissolving microneedles (DMNs), designed to release drugs and dissolve after skin insertion, have been spotlighted as a novel transdermal delivery system due to their advantages such as minimal pain and tissue damage, ability to self-administer, and no associated hazardous residues. The drug delivery efficacy of DMNs, however, is limited by incomplete insertion and the extended period required for DMN dissolution. Here, we introduce a novel DMN delivery system, DMN on an electrospun pillar array (DEPA), which can rapidly implant DMNs into skin. DMNs were fabricated on a pillar array covered by a fibrous sheet produced by electrospinning PLGA solution (14%, w/v). DMNs were implanted into the skin by manual application (press and vibration for 10 s) by tearing of the fibers hung on the 300-μm pillars. Separation of DMNs from the fibrous sheet was dependent on both pillar height and the properties of the fibrous sheet. After evaluation of the implantation and dissolution of DMNs with diffusion of red dye by taking cross-sectional images of porcine skin, the hypoglycemic effect of insulin loaded DEPA was examined using a healthy mouse model. This DMN array overcomes critical issues associated with the low penetration efficiency of flat patch-based DMNs, and will allow realization of patient convenience with the desired drug efficacy. PMID:26117659

  2. Precipitates in landfill leachate mediated by dissolved organic matters.

    PubMed

    Li, Zhenze; Xue, Qiang; Liu, Lei; Li, Jiangshan

    2015-04-28

    Clogging of landfill leachate collection system is so ubiquitous that it causes problems to landfills. Although precipitations of calcite and other minerals have been widely observed, the mechanism of precipitation remains obscure. We examined the clog composition, dissolved organic matters, leachate chemical compositions and the correlation of these variables in view of the precipitation process. It is shown that Dissolved Organic Carbon (DOC) inhibits precipitation of landfill leachate. Using the advanced NICA-Donnan model, the analysis of aqueous chemical reactions between Mg-Ca-DOC-CO2 suggests a good agreement with experimental observations. Calcite and dolomite are both found to be oversaturated in most of the landfill leachate samples. DOC is found to preferentially bind with Mg than Ca, leading to more likely precipitation of Calcite than dolomite from landfill leachate. The NICA-Donnan model gives a reasonable estimation of dolomite saturation index in a wide range of DOC. Modeling confirms the major precipitation mechanism in terms of alkaline earth metal carbonate. Uncertainties in model parameters are discussed with particular focus on DOC composition, functional group types and density concentration and the influential factors. PMID:25661175

  3. Screening for Dissolved Methane in Groundwater Across Texas Shale Plays

    NASA Astrophysics Data System (ADS)

    Nicot, J. P.; Mickler, P. J.; Hildenbrand, Z.; Larson, T.; Darvari, R.; Uhlman, K.; Smyth, R. C.; Scanlon, B. R.

    2014-12-01

    There is considerable interest in methane concentrations in groundwater, particularly as they relate to hydraulic fracturing in shale plays. Recent studies of aquifers in the footprint of several gas plays across the US have shown that (1) dissolved thermogenic methane may or may not be present in the shallow groundwater and (2) shallow thermogenic methane may be naturally occurring and emplaced through mostly vertical migration over geologic time and not necessarily a consequence of recent unconventional gas production. We are currently conducting a large sampling campaign across the state of Texas to characterize shallow methane in fresh-water aquifers overlying shale plays and other tight formations. We collected a total of ~800 water samples, ~500 in the Barnett, ~150 in the Eagle Ford, ~80 in the Haynesville shale plays as well as ~50 in the Delaware Basin of West Texas. Preliminary analytical results suggest that dissolved methane is not widespread in shallow groundwater and that, when present at concentrations exceeding 10 mg/L, it is often of thermogenic origin according to the isotopic signature and to the presence of other light hydrocarbons. The Barnett Shale contains a large methane hotspot (~ 2 miles wide) along the Hood-Parker county line which is likely of natural origin whereas the Eagle Ford and Haynesville shales, neglecting microbial methane, show more distributed methane occurrences. Samples from the Delaware Basin show no methane except close to blowouts.

  4. Formulation development and evaluation of mouth dissolving film of domperidone.

    PubMed

    Joshi, Pratikkumar; Patel, Harsha; Patel, Vishnu; Panchal, Rushi

    2012-03-01

    The present investigation was undertaken with the objective of formulating mouth dissolving film(s) of the antiemetic drug Domperidone to enhance the convenience and compliance by the elderly and pediatric patients. Domperidone is a drug of choice in case of nausea and vomiting produced by chemotherapy, migraine headaches, food poisoning and viral infections. It causes dopamine (D2 and D3) receptor blockage both at the chemoreceptor trigger zone and at the gastric level. It shows high first pass metabolism which results in poor bioavailability (10-15%). In view of high first pass metabolism and short plasma half-life it is an ideal candidate for rapid release drug delivery system. The solid dispersions of Domperidone were prepared with the use β-cyclodextrin in various ratios (1:1, 1:2, 1:3) and solubility study was performed to determine the ratio in which solubility of Domperidone was highest (1:3). The selected solid dispersions were then utilized for the preparation of film by solvent casting method utilizing HPMC E15 as a film forming agent and PEG-400 as plasticizer. Five formulae were prepared and were evaluated for their in vitro dissolution characteristics, in vitro disintegration time, and their physico-mechanical properties. The promising film (F1) showed the greatest drug dissolution (more than 75% within 15 min), satisfactory in vitro disintegration time (45 sec) and physico-mechanical properties that are suitable for mouth dissolving films. PMID:23066181

  5. Changing Export of Dissolved Black Carbon from Arctic Rivers

    NASA Astrophysics Data System (ADS)

    Stubbins, A.; Spencer, R. G.; Mann, P. J.; Dittmar, T.; Niggemann, J.; Holmes, R. M.; McClelland, J. W.

    2014-12-01

    Arctic rivers carry black carbon (BC) from Arctic soils to the ocean, linking two of the largest carbon stores on Earth. Wildfires have charred biomass since land plants emerged. BC, a refractory component of char, has accumulated in soils. In the oceans, dissolved BC (DBC) has also accumulated. Here we use samples and data collected as part of the long-term, high temporal resolution Arctic Great Rivers Observatory to model export of DBC from the six largest Arctic Rivers. Scaling to the pan-Arctic catchment, we report that ~3 million tons of DBC are delivered to the Arctic Ocean each year, which is ~8% of dissolved organic carbon loads to the Arctic Ocean. We suggest the transfer of Arctic river DBC to areas of deep water formation is a major source of DBC to the deep ocean carbon store. As the Arctic warms, greater wildfire occurrence is expected to produce more BC and changing hydrology and permafrost thaw to promote DBC export. Thus, the transfer of BC from Arctic soils to the ocean is predicted to increase.

  6. Distribution and molecular characterization of dissolved DNA in aquatic environments

    SciTech Connect

    DeFlaun, M.F.

    1987-01-01

    The distribution of dissolved DNA in oceanic, estuarine and freshwater environments in southwest Florida and the Gulf of Mexico was determined by using a method for the measurement of dissolved DNA based on the fluorescence of Hoechst 33258-DNA complexes. A wide range of molecular weights (determined by agarose gel electrophoresis) was found for extracellular DNA concentrated from various aquatic environments. A model system for probing extracellular DNA from aquatic environments was developed using the plasmid pS{beta}TK2.0 containing the herpes simplex thymidine kinase (TK) gene. Plasmid DNA and the TK gene fragment added to artificial seawater were concentrated and probed with ({sup 35}S) labelled TK to establish percent recovery and detection limits for the method. The degradation of plasmid DNA added to a natural seawater sample was monitored over a 36 h period by probing with the TK gene probe. Intact plasmid was detected for up to 4 h and DNA hybridizable to the TK probe was detected for up to 24 h. These methods were used to probe for the TK gene in environmental samples of extracellular DNA. Hybridization to the TK probe was detected in both freshwater and estuarine samples.

  7. Kinetics of desorption of organic compounds from dissolved organic matter.

    PubMed

    Kopinke, Frank-Dieter; Ramus, Ksenia; Poerschmann, Juergen; Georgi, Anett

    2011-12-01

    This study presents a new experimental technique for measuring rates of desorption of organic compounds from dissolved organic matter (DOM) such as humic substances. The method is based on a fast solid-phase extraction of the freely dissolved fraction of a solute when the solution is flushed through a polymer-coated capillary. The extraction interferes with the solute-DOM sorption equilibrium and drives the desorption process. Solutes which remain sorbed to DOM pass through the extraction capillary and can be analyzed afterward. This technique allows a time resolution for the desorption kinetics from subseconds up to minutes. It is applicable to the study of interaction kinetics between a wide variety of hydrophobic solutes and polyelectrolytes. Due to its simplicity it is accessible for many environmental laboratories. The time-resolved in-tube solid-phase microextraction (TR-IT-SPME) was applied to two humic acids and a surfactant as sorbents together with pyrene, phenanthrene and 1,2-dimethylcyclohexane as solutes. The results give evidence for a two-phase desorption kinetics: a fast desorption step with a half-life of less than 1 s and a slow desorption step with a half-life of more than 1 min. For aliphatic solutes, the fast-desorbing fraction largely dominates, whereas for polycyclic aromatic hydrocarbons such as pyrene, the slowly desorbing, stronger-bound fraction is also important. PMID:22035249

  8. Application of natural attenuation for the remediation of dissolved BTEX

    SciTech Connect

    De, M.A.; Wessner, E.; Graves, D.

    1995-12-31

    Gasoline released from leaking underground storage tanks adversely impacted soil and groundwater. The underground storage tanks were removed and a soil vapor extraction system was installed in the area of the tank excavation. Natural attenuation was chosen as the preferred strategy for groundwater treatment and a thorough evaluation of natural attenuation processes was undertaken. Previous site data and recently collected groundwater results were used to assess the effect of natural attenuation on the dissolved phase BTEX plume during the past three years. A median benzene biodegradation rate of 0.0056 per day was calculated using a first order decay equation. The biodegradative capacity of the aquifer was calculated to be at least 144,000 grams of hydrocarbon which exceeds the BTEX mass present in the aquifer. BIOPLUME II modeling of the aquifer indicated that natural attenuation, occurring at rates measured on the site, will effectively reduce the concentration of dissolved BTEX to target levels within 7 years. Plume migration is expected to be minimal.

  9. Dissolved Black Carbon in the South China Sea

    NASA Astrophysics Data System (ADS)

    Fang, Z.; Yang, W.; Chen, M.; Ma, H.

    2015-12-01

    Dissolved black carbon (DBC) has been ubiquitously reported in dissolved organic matter (DOM). However, the abundance and provenance of DBC in the ocean are not well understood. Here, DBC in the South China Sea (SCS) was determined at molecular level using the benzenepolycarboxylic acids (BPCAs) method. DBC showed high concentrations in the upper 100 m seawater with the average of 1.13 μmol l-1 (n=55). In the intermediate seawater (200-1500 m), DBC ranged from 0.67 to 0.89 μmol l-1 with the average of 0.78 μmol l-1 (n=9), exhibiting nearly homogeneous distributions. The vertical distribution pattern indicated that DBC significantly degraded in the photic zone, corresponding to an attenuate constant of 12.5±4.9 km-1. The ratios of B6CA/B3CAs increased downward, implying that aromatic condensation degree of DBC increase during transport from surface to deep water. Using the standing crops of DBC in the upper 200 m and the residence time of seawater, atmospheric deposition of DBC was estimated to be 1.94 TgC yr-1, accounting for around 16% of the global BC deposition. Our study highlights that DBC could be an important component of ocean carbon cycling in Pacific Asia Marginal Seas.

  10. Groundwater-transported dissolved organic nitrogen exports from coastal watersheds

    USGS Publications Warehouse

    Kroeger, K.D.; Cole, Marci L.; Valiela, I.

    2006-01-01

    We analyzed groundwater-transported nitrogen (N) exports from 41 watershed segments that comprised 10 Cape Cod, Massachusetts watersheds to test the hypotheses that chemical form of N exports is related to land use and to length of flow paths through watersheds. In the absence of human habitation, these glacial outwash-plain watersheds exported largely dissolved organic N (DON) but at relatively low annual rate. Addition of people to watersheds increased rates of both total dissolved N (TDN) and DON export through groundwater. Percent of TDN as DON in groundwater was negatively related to path length of groundwater through aquifers, but %DON was not significantly related to population density on the watersheds. DON was often the dominant form of N exported from the watersheds, even at high population densities. Our results suggest that natural sources are not entirely responsible for organic N exports from watersheds, but, instead, a substantial portion of anthropogenic N introduced to watersheds is exported as DON. This finding is in disagreement with previous results, which suggest that anthropogenic N is exported from watersheds largely as NO 3- and that DON exported from watersheds is from natural sources. ?? 2006, by the American Society of Limnology and Oceanography, Inc.

  11. Cracking of duplex stainless steel due to dissolved hydrogen

    SciTech Connect

    Huang, J.H.; Altstetter, C.J.

    1995-05-01

    Ferallium 255 duplex stainless steel was cathodically precharged with hydrogen at 265 C in a molten salt electrolyte. Sustained load tests were carried out in air at 0 C, 25 C and 50 C with average hydrogen contents from 3 to 15 wt ppm. The DC potential drop method was calibrated with optical measurements to continuously monitor the crack position and allow calculation of crack velocity and stress intensity. The crack velocity vs stress intensity (K) curves generally rose gradually over a large range in K and had definite thresholds for subcritical crack growth. Second and third stages were not always clearly delineated. Threshold stress intensities decreased as hydrogen content increased. An identifiable stage 2 occurred most often for alloys containing about 10 wt ppm dissolved hydrogen. The crack growth velocities generally increased with increasing temperature or hydrogen content. As the dissolved hydrogen increased, the fracture mode changed from microvoid coalescence (MVC) to microcrack coalescence (MCC) with some tearing ridges. At high hydrogen content, both ferrite and austenite phases showed brittle morphology, which was identical to the fracture surface of the uncharged specimens tested in hydrogen gas at 108 kPa pressure. Comparing the embrittling effect of internal hydrogen with that of external hydrogen it is found that the threshold stress intensity in hydrogen gas at 1 atm is lower than that at the highest internal hydrogen concentration (15 wt ppm).

  12. Global effects of agriculture on fluvial dissolved organic matter

    NASA Astrophysics Data System (ADS)

    Graeber, Daniel; Boëchat, Iola G.; Encina-Montoya, Francisco; Esse, Carlos; Gelbrecht, Jörg; Goyenola, Guillermo; Gücker, Björn; Heinz, Marlen; Kronvang, Brian; Meerhoff, Mariana; Nimptsch, Jorge; Pusch, Martin T.; Silva, Ricky C. S.; von Schiller, Daniel; Zwirnmann, Elke

    2015-11-01

    Agricultural land covers approximately 40% of Earth’s land surface and affects hydromorphological, biogeochemical and ecological characteristics of fluvial networks. In the northern temperate region, agriculture also strongly affects the amount and molecular composition of dissolved organic matter (DOM), which constitutes the main vector of carbon transport from soils to fluvial networks and to the sea, and is involved in a large variety of biogeochemical processes. Here, we provide first evidence about the wider occurrence of agricultural impacts on the concentration and composition of fluvial DOM across climate zones of the northern and southern hemispheres. Both extensive and intensive farming altered fluvial DOM towards a more microbial and less plant-derived composition. Moreover, intensive farming significantly increased dissolved organic nitrogen (DON) concentrations. The DOM composition change and DON concentration increase differed among climate zones and could be related to the intensity of current and historical nitrogen fertilizer use. As a result of agriculture intensification, increased DON concentrations and a more microbial-like DOM composition likely will enhance the reactivity of catchment DOM emissions, thereby fuelling the biogeochemical processing in fluvial networks, and resulting in higher ecosystem productivity and CO2 outgassing.

  13. Photochemical and Nonphotochemical Transformations of Cysteine with Dissolved Organic Matter.

    PubMed

    Chu, Chiheng; Erickson, Paul R; Lundeen, Rachel A; Stamatelatos, Dimitrios; Alaimo, Peter J; Latch, Douglas E; McNeill, Kristopher

    2016-06-21

    Cysteine (Cys) plays numerous key roles in the biogeochemistry of natural waters. Despite its importance, a full assessment of Cys abiotic transformation kinetics, products and pathways under environmental conditions has not been conducted. This study is a mechanistic evaluation of the photochemical and nonphotochemical (dark) transformations of Cys in solutions containing chromophoric dissolved organic matter (CDOM). The results show that Cys underwent abiotic transformations under both dark and irradiated conditions. Under dark conditions, the transformation rates of Cys were moderate and were highly pH- and temperature-dependent. Under UVA or natural sunlight irradiations, Cys transformation rates were enhanced by up to two orders of magnitude compared to rates under dark conditions. Product analysis indicated cystine and cysteine sulfinic acid were the major photooxidation products. In addition, this study provides an assessment of the contributions of singlet oxygen, hydroxyl radical, hydrogen peroxide, and triplet dissolved organic matter to the CDOM-sensitized photochemical oxidation of Cys. The results suggest that another unknown pathway was dominant in the CDOM-sensitized photodegradation of Cys, which will require further study to identify. PMID:27172378

  14. A simple headspace equilibration method for measuring dissolved methane

    USGS Publications Warehouse

    Magen, C; Lapham, L.L.; Pohlman, John W.; Marshall, Kristin N.; Bosman, S.; Casso, Michael; Chanton, J.P.

    2014-01-01

    Dissolved methane concentrations in the ocean are close to equilibrium with the atmosphere. Because methane is only sparingly soluble in seawater, measuring it without contamination is challenging for samples collected and processed in the presence of air. Several methods for analyzing dissolved methane are described in the literature, yet none has conducted a thorough assessment of the method yield, contamination issues during collection, transport and storage, and the effect of temperature changes and preservative. Previous extraction methods transfer methane from water to gas by either a "sparge and trap" or a "headspace equilibration" technique. The gas is then analyzed for methane by gas chromatography. Here, we revisit the headspace equilibration technique and describe a simple, inexpensive, and reliable method to measure methane in fresh and seawater, regardless of concentration. Within the range of concentrations typically found in surface seawaters (2-1000 nmol L-1), the yield of the method nears 100% of what is expected from solubility calculation following the addition of known amount of methane. In addition to being sensitive (detection limit of 0.1 ppmv, or 0.74 nmol L-1), this method requires less than 10 min per sample, and does not use highly toxic chemicals. It can be conducted with minimum materials and does not require the use of a gas chromatograph at the collection site. It can therefore be used in various remote working environments and conditions.

  15. Molecular-level dynamics of refractory dissolved organic matter

    NASA Astrophysics Data System (ADS)

    Niggemann, J.; Gerdts, G.; Dittmar, T.

    2012-04-01

    Refractory dissolved organic matter (DOM) accounts for most of the global oceanic organic carbon inventory. Processes leading to its formation and factors determining its stability are still largely unknown. We hypothesize that refractory DOM carries a universal molecular signature. Characterizing spatial and temporal variability in this universal signature is a key to understanding dynamics of refractory DOM. We present results from a long-term study of the DOM geo-metabolome in the open North Sea. Geo-metabolomics considers the entity of DOM as a population of compounds, each characterized by a specific function and reactivity in the cycling of energy and elements. Ten-thousands of molecular formulae were identified in DOM by ultrahigh resolution mass spectrometry analysis (FT-ICR-MS, Fourier-Transform Ion Cyclotron Resonance Mass Spectrometry). The DOM pool in the North Sea was influenced by a complex interplay of processes that produced, transformed and degraded dissolved molecules. We identified a stable fraction in North Sea DOM with a molecular composition similar to deep ocean DOM. Molecular-level changes in this stable fraction provide novel information on dynamics and interactions of refractory DOM.

  16. The effects of dissolved gas supersaturation on white sturgeon larvae

    USGS Publications Warehouse

    Counihan, T.D.; Miller, A.I.; Mesa, M.G.; Parsley, M.J.

    2000-01-01

    Spill at dams has caused supersaturation of atmospheric gas in waters of the Columbia and Snake rivers and raised concerns about the effects of dissolved gas supersaturation (DGS) on white sturgeons Acipenser transmontanus. The timing and location of white sturgeon spawning and the dispersal of white sturgeon larvae from incubation areas makes the larval stage potentially vulnerable to the effects of DGS. To assess the effects of DGS on white sturgeon larvae, we exposed larvae to mean total dissolved gas (TDG) levels of 118% and 131% saturation in laboratory bioassay tests. Gas bubble trauma (GBT) was manifested as a gas bubble in the buccal cavity, nares, or both and it first occurred at developmental stages characterized by the formation of the mouth and gills. Exposure times of 15 min were sufficient to elicit these signs in larvae in various stages of development. No mortality was observed in larvae exposed to 118% TDG for 10 d, but 50% mortality occurred after a 13-d exposure to 131% TDG. The signs of GBT we observed resulted in positive buoyancy and alterations in behavior that may affect the dispersal and predation vulnerability of white sturgeon larvae. The exact depth distribution of dispersing white sturgeon larvae in the Columbia River currently is unknown. Thus, our results may represent a worst-case scenario if white sturgeon larvae are dispersed at depths with insufficient hydrostatic pressure to compensate for high TDG levels.

  17. Mathematical modeling of wastewater-derived biodegradable dissolved organic nitrogen.

    PubMed

    Simsek, Halis

    2016-11-01

    Wastewater-derived dissolved organic nitrogen (DON) typically constitutes the majority of total dissolved nitrogen (TDN) discharged to surface waters from advanced wastewater treatment plants (WWTPs). When considering the stringent regulations on nitrogen discharge limits in sensitive receiving waters, DON becomes problematic and needs to be reduced. Biodegradable DON (BDON) is a portion of DON that is biologically degradable by bacteria when the optimum environmental conditions are met. BDON in a two-stage trickling filter WWTP was estimated using artificial intelligence techniques, such as adaptive neuro-fuzzy inference systems, multilayer perceptron, radial basis neural networks (RBNN), and generalized regression neural networks. Nitrite, nitrate, ammonium, TDN, and DON data were used as input neurons. Wastewater samples were collected from four different locations in the plant. Model performances were evaluated using root mean square error, mean absolute error, mean bias error, and coefficient of determination statistics. Modeling results showed that the R(2) values were higher than 0.85 in all four models for all wastewater samples, except only R(2) in the final effluent sample for RBNN modeling was low (0.52). Overall, it was found that all four computing techniques could be employed successfully to predict BDON. PMID:27019968

  18. Dissolved organic nitrogen in precipitation: Collection, analysis and atmospheric flux

    SciTech Connect

    Scudlark, J.R.; Church, T.M.; Russell, K.M.; Montag, J.A.; Maben, J.R.; Keene, W.C.; Galloway, J.N.

    1995-12-31

    Recent studies have documented the importance of atmosphere inorganic nitrogen deposition to coastal waters. However, due to the limited number of field measurements and concerns about the reliability of measurement techniques, the aeolian flux of organic N is very uncertain. Coordinated studies have been initiated at Lewes, DE and Charlottesville, VA to evaluate collection and analysis techniques for dissolved organic nitrogen (DON) in precipitation and to provide preliminary estimate of DON wet fluxes. Sampling was conducted both manually and employing an automated wet-only collector (ACM) on a daily basis. A total of 37 events were analyzed from October 1993 through December 1994. Side-by-side comparisons of standard white HDPE buckets and stainless steel and glass collection vessels indicate sampling artifacts associate with plastic buckets. DON in precipitation appears to be highly labile, with significant losses observed in some samples within 12 hours. Analytical methods evaluated include persulfate wet chemical oxidation, UV photo-oxidation and a modified high temperature instrumental (ANTEK 7000) technique. Based on preliminary results, the volume-weighted average concentration of DON in precipitation at the mid-Atlantic coast is 9.1 {micro}moles/1. On an annual basis, DON compromises 23% of the total dissolved nitrogen in precipitation, varying from 0--64% on an event basis. From an ecological perspective, DON wet flux represents a quantitatively important exogenous source of N to coastal waters such as Chesapeake Bay.

  19. Continuous Dissolved Oxygen Measurements and Modelling Metabolism in Peatland Streams

    PubMed Central

    Dick, Jonathan J.; Soulsby, Chris; Birkel, Christian; Malcolm, Iain; Tetzlaff, Doerthe

    2016-01-01

    Stream water dissolved oxygen was monitored in a 3.2km2 moorland headwater catchment in the Scottish Highlands. The stream consists of three 1st order headwaters and a 2nd order main stem. The stream network is fringed by peat soils with no riparian trees, though dwarf shrubs provide shading in the lower catchment. Dissolved oxygen (DO) is regulated by the balance between atmospheric re-aeration and the metabolic processes of photosynthesis and respiration. DO was continuously measured for >1 year and the data used to calibrate a mass balance model, to estimate primary production, respiration and re-aeration for a 1st order site and in the 2nd order main stem. Results showed that the stream was always heterotrophic at both sites. Sites were most heterotrophic in the summer reflecting higher levels of stream metabolism. The 1st order stream appeared more heterotrophic which was consistent with the evident greater biomass of macrophytes in the 2nd order stream, with resulting higher primary productivity. Comparison between respiration, primary production, re-aeration and potential physical controls revealed only weak relationships. However, the most basic model parameters (e.g. the parameter linking light and photosynthesis) controlling ecosystem processes resulted in significant differences between the sites which seem related to the stream channel geometry. PMID:27556278

  20. Continuous Dissolved Oxygen Measurements and Modelling Metabolism in Peatland Streams.

    PubMed

    Dick, Jonathan J; Soulsby, Chris; Birkel, Christian; Malcolm, Iain; Tetzlaff, Doerthe

    2016-01-01

    Stream water dissolved oxygen was monitored in a 3.2km2 moorland headwater catchment in the Scottish Highlands. The stream consists of three 1st order headwaters and a 2nd order main stem. The stream network is fringed by peat soils with no riparian trees, though dwarf shrubs provide shading in the lower catchment. Dissolved oxygen (DO) is regulated by the balance between atmospheric re-aeration and the metabolic processes of photosynthesis and respiration. DO was continuously measured for >1 year and the data used to calibrate a mass balance model, to estimate primary production, respiration and re-aeration for a 1st order site and in the 2nd order main stem. Results showed that the stream was always heterotrophic at both sites. Sites were most heterotrophic in the summer reflecting higher levels of stream metabolism. The 1st order stream appeared more heterotrophic which was consistent with the evident greater biomass of macrophytes in the 2nd order stream, with resulting higher primary productivity. Comparison between respiration, primary production, re-aeration and potential physical controls revealed only weak relationships. However, the most basic model parameters (e.g. the parameter linking light and photosynthesis) controlling ecosystem processes resulted in significant differences between the sites which seem related to the stream channel geometry. PMID:27556278

  1. Global effects of agriculture on fluvial dissolved organic matter.

    PubMed

    Graeber, Daniel; Boëchat, Iola G; Encina-Montoya, Francisco; Esse, Carlos; Gelbrecht, Jörg; Goyenola, Guillermo; Gücker, Björn; Heinz, Marlen; Kronvang, Brian; Meerhoff, Mariana; Nimptsch, Jorge; Pusch, Martin T; Silva, Ricky C S; von Schiller, Daniel; Zwirnmann, Elke

    2015-01-01

    Agricultural land covers approximately 40% of Earth's land surface and affects hydromorphological, biogeochemical and ecological characteristics of fluvial networks. In the northern temperate region, agriculture also strongly affects the amount and molecular composition of dissolved organic matter (DOM), which constitutes the main vector of carbon transport from soils to fluvial networks and to the sea, and is involved in a large variety of biogeochemical processes. Here, we provide first evidence about the wider occurrence of agricultural impacts on the concentration and composition of fluvial DOM across climate zones of the northern and southern hemispheres. Both extensive and intensive farming altered fluvial DOM towards a more microbial and less plant-derived composition. Moreover, intensive farming significantly increased dissolved organic nitrogen (DON) concentrations. The DOM composition change and DON concentration increase differed among climate zones and could be related to the intensity of current and historical nitrogen fertilizer use. As a result of agriculture intensification, increased DON concentrations and a more microbial-like DOM composition likely will enhance the reactivity of catchment DOM emissions, thereby fuelling the biogeochemical processing in fluvial networks, and resulting in higher ecosystem productivity and CO2 outgassing. PMID:26541809

  2. How well do global ocean biogeochemistry models simulate dissolved iron distributions?

    NASA Astrophysics Data System (ADS)

    Tagliabue, Alessandro; Aumont, Olivier; DeAth, Ros; Dunne, John P.; Dutkiewicz, Stephanie; Galbraith, Eric; Misumi, Kazuhiro; Moore, J. Keith; Ridgwell, Andy; Sherman, Elliot; Stock, Charles; Vichi, Marcello; Völker, Christoph; Yool, Andrew

    2016-02-01

    Numerical models of ocean biogeochemistry are relied upon to make projections about the impact of climate change on marine resources and test hypotheses regarding the drivers of past changes in climate and ecosystems. In large areas of the ocean, iron availability regulates the functioning of marine ecosystems and hence the ocean carbon cycle. Accordingly, our ability to quantify the drivers and impacts of fluctuations in ocean ecosystems and carbon cycling in space and time relies on first achieving an appropriate representation of the modern marine iron cycle in models. When the iron distributions from 13 global ocean biogeochemistry models are compared against the latest oceanic sections from the GEOTRACES program, we find that all models struggle to reproduce many aspects of the observed spatial patterns. Models that reflect the emerging evidence for multiple iron sources or subtleties of its internal cycling perform much better in capturing observed features than their simpler contemporaries, particularly in the ocean interior. We show that the substantial uncertainty in the input fluxes of iron results in a very wide range of residence times across models, which has implications for the response of ecosystems and global carbon cycling to perturbations. Given this large uncertainty, iron fertilization experiments based on any single current generation model should be interpreted with caution. Improvements to how such models represent iron scavenging and also biological cycling are needed to raise confidence in their projections of global biogeochemical change in the ocean.

  3. Effects of dissolved CO2 on Shallow Freshwater Microbial Communities simulating a CO2 Leakage Scenario

    NASA Astrophysics Data System (ADS)

    Gulliver, D. M.; Lowry, G. V.; Gregory, K.

    2013-12-01

    Geological carbon sequestration is likely to be part of a comprehensive strategy to minimize the atmospheric release of greenhouse gasses, establishing a concern of sequestered CO2 leakage into overlying potable aquifers. Leaking CO2 may affect existing biogeochemical processes and therefore water quality. There is a critical need to understand the evolution of CO2 exposed microbial communities that influence the biogeochemistry in these freshwater aquifers. The evolution of microbial ecology for different CO2 exposure concentrations was investigated using fluid-slurry samples obtained from a shallow freshwater aquifer (55 m depth, 0.5 MPa, 22 °C, Escatawpa, MS). The microbial community of well samples upstream and downstream of CO2 injection was characterized. In addition, batch vessel experiments were conducted with the upstream aquifer samples exposed to varying pCO2 from 0% to 100% under reservoir temperature and pressure for up to 56 days. The microbial community of the in situ experiment and the batch reactor experiment were analyzed with 16S rRNA clone libraries and qPCR. In both the in situ experiment and the batch reactor experiment, DNA concentration did not correlate with CO2 exposure. Both the in situ experiment and the batch reactors displayed a changing microbial community with increased CO2 exposure. The well water isolate, Curvibacter, appeared to be the most tolerant genus to high CO2 concentrations in the in situ experiments and to mid-CO2 concentrations in the batch reactors. In batch reactors with pCO2 concentrations higher than experienced in situ (pCO2 = 0.5 MPa), Pseudomonas appeared to be the most tolerant genus. Findings provide insight into a dynamic biogeochemical system that will alter with CO2 exposure. Adapted microbial populations will eventually give rise to the community that will impact the metal mobility and water quality. Knowledge of the surviving microbial populations will enable improved models for predicting the fate of CO2 following leakage and lead to better strategies for ensuring the quality of potable aquifer water.

  4. Yucca Mountain Area Saturated Zone Dissolved Organic Carbon Isotopic Data

    SciTech Connect

    Thomas, James; Decker, David; Patterson, Gary; Peterman, Zell; Mihevc, Todd; Larsen, Jessica; Hershey, Ronald

    2007-06-25

    Groundwater samples in the Yucca Mountain area were collected for chemical and isotopic analyses and measurements of water temperature, pH, specific conductivity, and alkalinity were obtained at the well or spring at the time of sampling. For this project, groundwater samples were analyzed for major-ion chemistry, deuterium, oxygen-18, and carbon isotopes of dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC). The U.S. Geological Survey (USGS) performed all the fieldwork on this project including measurement of water chemistry field parameters and sample collection. The major ions dissolved in the groundwater, deuterium, oxygen-18, and carbon isotopes of dissolved inorganic carbon (DIC) were analyzed by the USGS. All preparation and processing of samples for DOC carbon isotopic analyses and geochemical modeling were performed by the Desert Research Institute (DRI). Analysis of the DOC carbon dioxide gas produced at DRI to obtain carbon-13 and carbon-14 values was conducted at the University of Arizona Accelerator Facility (a NSHE Yucca Mountain project QA qualified contract facility). The major-ion chemistry, deuterium, oxygen-18, and carbon isotopes of DIC were used in geochemical modeling (NETPATH) to determine groundwater sources, flow paths, mixing, and ages. The carbon isotopes of DOC were used to calculate groundwater ages that are independent of DIC model corrected carbon-14 ages. The DIC model corrected carbon-14 calculated ages were used to evaluate groundwater travel times for mixtures of water including water beneath Yucca Mountain. When possible, groundwater travel times were calculated for groundwater flow from beneath Yucca Mountain to down gradient sample sites. DOC carbon-14 groundwater ages were also calculated for groundwaters in the Yucca Mountain area. When possible, groundwater travel times were estimated for groundwater flow from beneath Yucca Mountain to down gradient groundwater sample sites using the DOC calculated

  5. Identification of key parameters controlling dissolved oxygen migration and attenuation in fractured crystalline rocks.

    PubMed

    Spiessl, S M; MacQuarrie, K T B; Mayer, K U

    2008-01-28

    In the crystalline rocks of the Canadian Shield, geochemical conditions are currently reducing at depths of 500-1000 m. However, during future glacial periods, altered hydrologic conditions could potentially result in enhanced recharge of glacial melt water containing a relatively high concentration of dissolved oxygen (O2). It is therefore of interest to investigate the physical and geochemical processes, including naturally-occurring redox reactions, that may control O2 ingress. In this study, the reactive transport code MIN3P is used in combination with 2k factorial analyses to identify the most important parameters controlling oxygen migration and attenuation in fractured crystalline rocks. Scenarios considered are based on simplified conceptual models that include a single vertical fracture, or a fracture zone, contained within a rock matrix that extends from the ground surface to a depth of 500 m. Consistent with field observations, Fe(II)-bearing minerals are present in the fractures (i.e. chlorite) and the rock matrix (biotite and small quantities of pyrite). For the parameter ranges investigated, results indicate that for the single fracture case, the most influential factors controlling dissolved O2 ingress are flow velocity in the fracture, fracture aperture, and the biotite reaction rate in the rock matrix. The most important parameters for the fracture zone simulations are flow velocity in the individual fractures, pO2 in the recharge water, biotite reaction rate, and to a lesser degree the abundance and reactivity of chlorite in the fracture zone, and the fracture zone width. These parameters should therefore receive increased consideration during site characterization, and in the formulation of site-specific models intended to predict O2 behavior in crystalline rocks. PMID:17935829

  6. Photochemical Oxidation of Dissolved Elemental Mercury by Carbonate Radicals in Water

    SciTech Connect

    He, Feng; Zhao, Weirong; Liang, Liyuan; Gu, Baohua

    2014-11-11

    Photochemical oxidation of dissolved elemental mercury [Hg(0)] affects mercury chemical speciation and its transfer at the water-air interface in the aquatic environment. The mechanisms and factors that control Hg(0) photooxidation, however, are not completely understood, especially in natural freshwaters containing dissolved organic matter (DOM) and carbonate. Here, we evaluate Hg(0) photooxidation rates affected by various reactive ionic species [e.g., DOM, CO32-, NO3-] and free radicals in a creek water and a phosphate buffer solution (pH=8) under simulated solar irradiation. We report a high Hg(0) photooxidation rate (k = 1.44 h-1) in the presence of both HCO32- and NO3-, whereas HCO32-, NO3-, or DOM alone increased the oxidation rate slightly (k = 0.1 0.17 h-1). Using scavengers and enhancers for singlet oxygen (1O2) and hydroxyl (HO ) radicals, as well as electron paramagnetic resonance spectroscopy, we identify that carbonate radicals (CO3 ∙-) primarily drive the Hg(0) photooxidation, whereas addition of DOM resulted in a 2-fold decrease in Hg(0) oxidation. This study identifies an unrecognized pathway of Hg(0) photooxidation by CO3 ∙- radicals and the inhibitory effect of DOM, which could be important in assessing Hg transformation and fate in water containing carbonate such as hard water and seawater.

  7. FINAL REPORT INTEGRATED DM1200 MELTER TESTING OF REDOX EFFECTS USING HLW AZ-101 AND C-106/AY-102 SIMULANTS VSL-04R4800-1 REV 0 5/6/

    SciTech Connect

    KRUGER AA; MATLACK KS; GONG W; BARDAKCI T; D'ANGELO NA; LUTZE W; BIZOT PM; CALLOW RA; BRANDYS M; KOT WK; PEGG IL

    2011-12-29

    This report documents melter and off-gas performance results obtained on the DM1200 HLW Pilot Melter during processing of AZ-101 and C-106/AY-102 HLW simulants. The tests reported herein are a subset of three tests from a larger series of tests described in the Test Plan for the work; results from the remaining tests will be reported separately. Three nine day tests, one with AZ-101 and two with C-106/AY-102 feeds were conducted with variable amounts of added sugar to address the effects of redox. The test with AZ-101 included ruthenium spikes to also address the effects of redox on ruthenium volatility. One of tests addressed the effects of increased flow-sheet nitrate levels using C-106/AY-102 feeds. With high nitrate/nitrite feeds (such as WTP LAW feeds), reductants are required to prevent melt foaming and deleterious effects on glass production rates. Sugar is the baseline WTP reductant for this purpose. WTP HLW feeds typically have relatively low nitrate/nitrite content in comparison to the organic carbon content and, therefore, have typically not required sugar additions. However, HLW feed variability, particularly with respect to nitrate levels, may necessitate the use of sugar in some instances. The tests reported here investigate the effects of variable sugar additions to the melter feed as well as elevated nitrate levels in the waste. Variables held constant to the extent possible included melt temperature, bubbling rate, plenum temperature, cold cap coverage, the waste simulant composition, and the target glass composition. The principal objectives of the DM1200 melter testing were to determine the achievable glass production rates for simulated HLW feeds with variable amounts of added sugar and increased nitrate levels; characterize melter off-gas emissions; characterize the performance of the prototypical off-gas system components as well as their integrated performance; characterize the feed, glass product, and off-gas effluents; and perform pre- and

  8. Modeling the simultaneous transport of silver nanoparticles and dissolved silver ions in water-saturated sand columns

    NASA Astrophysics Data System (ADS)

    Taghavy, A.; Wang, Y.; Mittelman, A.; Becker, M. D.; Pennell, K. D.; Abriola, L. M.

    2011-12-01

    Concerns over the potential adverse impacts of nanosilver particles (nAg) on human health and the environment have arisen based upon their widespread use in various commercial and biomedical products. In addition, in situ dissolution of deposited nAg could enhance its environmental impact through the formation of dissolved silver ion (Ag+) plumes. A hybrid mathematical model is presented that simulates the simultaneous reactive transport of nAg/Ag+ in porous media. The simulator couples a Lagrangian Random Walk-based Particle Tracking (RWPT) method for nAg transport with a conventional Eulerian Finite Differencing (FD) scheme for the reactive transport of dissolved solutes. In the absence of oxidants other than dissolved oxygen (DO), nAg is assumed to dissolve via a cooperative oxidation reaction with DO and proton ions (H+), and dissolution is modeled by a first-order kinetic expression. An existing empirical correlation is implemented for evaluation of the dissolution rate constant from physiochemical characteristics of the system and nanoparticles, including solution pH, particle specific surface area (SSA), and temperature. The hybrid modeling approach enables the consideration of different particle size classes and the associated particle-specific dissolution rates. The utility of simulator is demonstrated by modeling results obtained from nAg/ Ag+ transport studies performed in ca. 10.8-cm long borosilicate glass columns with an inside diameter of 2.5 cm. Three column experiments were performed at a constant flow rate, yielding a particle approach velocity of 7.68±0.04 m/day, at dissolved oxygen concentrations ranging from 1.65 mg/L to 8.99 mg/L. A 3 pore volume pulse of nAg suspension, containing 3.17±0.07 mg/L total Ag and 10mM NaNO3 at pH 7.07, was injected into water-saturated columns packed with washed 40-50 mesh Ottawa sand. Following nAg injection, the columns were flushed with nAg-free background solution for an additional 3 pore volumes, which

  9. CLOSE STELLAR ENCOUNTERS IN YOUNG, SUBSTRUCTURED, DISSOLVING STAR CLUSTERS: STATISTICS AND EFFECTS ON PLANETARY SYSTEMS

    SciTech Connect

    Craig, Jonathan; Krumholz, Mark R.

    2013-06-01

    Both simulations and observations indicate that stars form in filamentary, hierarchically clustered associations, most of which disperse into their galactic field once feedback destroys their parent clouds. However, during their early evolution in these substructured environments, stars can undergo close encounters with one another that might have significant impacts on their protoplanetary disks or young planetary systems. We perform N-body simulations of the early evolution of dissolving, substructured clusters with a wide range of properties, with the aim of quantifying the expected number and orbital element distributions of encounters as a function of cluster properties. We show that the presence of substructure both boosts the encounter rate and modifies the distribution of encounter velocities compared to what would be expected for a dynamically relaxed cluster. However, the boost only lasts for a dynamical time, and as a result the overall number of encounters expected remains low enough that gravitational stripping is unlikely to be a significant effect for the vast majority of star-forming environments in the Galaxy. We briefly discuss the implications of this result for models of the origin of the solar system, and of free-floating planets. We also provide tabulated encounter rates and orbital element distributions suitable for inclusion in population synthesis models of planet formation in a clustered environment.

  10. Sensitivity of stream dissolved organic carbon to temperature and discharge: Implications of future climates

    NASA Astrophysics Data System (ADS)

    Winterdahl, Mattias; Laudon, Hjalmar; Lyon, Steve W.; Pers, Charlotta; Bishop, Kevin

    2016-01-01

    Dissolved organic carbon (DOC) is a significant constituent in aquatic ecosystems with concentrations in streams influenced by both temperature and water flow pathway dynamics associated with changes in discharge (streamflow). We investigated the sensitivity of DOC concentrations in 12 high-latitude headwater streams to changes in temperature and discharge using a mathematical model. The implications of differences in sensitivities were explored by using downscaled projections of air temperature and discharge to simulate possible trajectories of DOC concentrations in a changing climate. We found two distinct responses: (i) catchments where stream DOC sensitivity was high to temperature but low to discharge and (ii) catchments where stream DOC sensitivity was low to temperature but high to discharge. Streams with strong seasonal DOC dynamics were more sensitive to temperature changes than nonseasonal systems. In addition, stream DOC sensitivity to discharge was strongly correlated with vertical soil water DOC differences in the near-stream zone. Simulations of possible future changes in DOC concentrations indicated median increases of about 4-24% compared to current levels when using projections of air temperature and discharge but even larger increases were observed for base flow concentrations (13-42%). Streams with high-temperature sensitivity showed the largest increases in DOC concentrations. Our results suggest that future climatic changes could bring significant increases in surface water DOC concentrations in boreal and hemiboreal areas but that the response ultimately is dependent on vertical soil solution DOC differences and soil organic carbon distribution.

  11. Collective and convective effects compete in patterns of dissolving surface droplets.

    PubMed

    Laghezza, Gianluca; Dietrich, Erik; Yeomans, Julia M; Ledesma-Aguilar, Rodrigo; Kooij, E Stefan; Zandvliet, Harold J W; Lohse, Detlef

    2016-06-29

    The effects of neighboring droplets on the dissolution of a sessile droplet, i.e. collective effects, are investigated both experimentally and numerically. On the experimental side small approximately 20 nL mono-disperse surface droplets arranged in an ordered pattern were dissolved and their size evolution is studied optically. The droplet dissolution time was studied for various droplet patterns. On the numerical side, lattice-Boltzmann simulations were performed. Both simulations and experiments show that the dissolution time of a droplet placed in the center of a pattern can increase by as much as 60% as compared to a single, isolated droplet, due to the shielding effect of the neighboring droplets. However, the experiments also show that neighboring droplets enhance the buoyancy driven convective flow of the bulk, increasing the mass exchange and counteracting collective effects. We show that this enhanced convection can reduce the dissolution time of droplets at the edges of the pattern to values below that of a single, isolated droplet. PMID:27270609

  12. Human-driven changes in dissolved phosphorus deposition to the ocean

    NASA Astrophysics Data System (ADS)

    Myriokefalitakis, Stelios; Nenes, Athanasios; Kanakidou, Maria

    2016-04-01

    The atmospheric cycle of phosphorus (P) is parameterized in a global 3-D chemistry-transport model by taking into account the primary emissions of total (TP) and dissolved P (PO4) associated with dust, sea-salt, bioaerosols and combustion particles of anthropogenic and natural sources. Mineral sources are calculated to contribute by roughly 80% to the TP emissions. The calculated annual deposition flux of PO4 presents strong spatial and temporal variability with about 30% occurring over the ocean. Sensitivity simulations using preindustrial (year 1850), present (year 2008) and future (year 2100) anthropogenic and biomass burning emission scenarios, indicate that an increase in dust-P dissolution flux may have occurred in the last 150 years due to increasing atmospheric acidity due to anthropogenic emissions. On the opposite, a decrease of dust-P containing dissolution flux is projected for near future, since air-quality regulations are expected to reduce atmospheric acidity compared to present-day. Present day simulations of atmospheric P aerosol concentrations and deposition fluxes compare satisfactorily with available observations, thus, providing confidence to the model results. This work has been co-financed by the European Union (European Social Fund - ESF) and Greek national funds through the Operational Program "Education and Lifelong Learning" of the National Strategic Reference Framework (NSRF) - Research Funding Program: ARISTEIA - PANOPLY (Pollution Alters Natural Aerosol Composition: implications for Ocean Productivity, cLimate and air qualitY) grant.

  13. Modeling dissolved organic carbon in temperate forest soils: TRIPLEX-DOC model development and validation

    NASA Astrophysics Data System (ADS)

    Wu, H.; Peng, C.; Moore, T. R.; Hua, D.; Li, C.; Zhu, Q.; Peichl, M.; Arain, M. A.; Guo, Z.

    2014-05-01

    Even though dissolved organic carbon (DOC) is the most active carbon (C) cycling in soil organic carbon (SOC) pools, it receives little attention from the global C budget. DOC fluxes are critical to aquatic ecosystem inputs and contribute to the C balance of terrestrial ecosystems, but few ecosystem models have attempted to integrate DOC dynamics into terrestrial C cycling. This study introduces a new process-based model, TRIPLEX-DOC, that is capable of estimating DOC dynamics in forest soils by incorporating both ecological drivers and biogeochemical processes. TRIPLEX-DOC was developed from Forest-DNDC, a biogeochemical model simulating C and nitrogen (N) dynamics, coupled with a new DOC process module that predicts metabolic transformations, sorption/desorption, and DOC leaching in forest soils. The model was validated against field observations of DOC concentrations and fluxes at white pine forest stands located in southern Ontario, Canada. The model was able to simulate seasonal dynamics of DOC concentrations and the magnitudes observed within different soil layers, as well as DOC leaching in the age sequence of these forests. Additionally, TRIPLEX-DOC estimated the effect of forest harvesting on DOC leaching, with a significant increase following harvesting, illustrating that land use change is of critical importance in regulating DOC leaching in temperate forests as an important source of C input to aquatic ecosystems.

  14. Agent-based modeling of hyporheic dissolved organic carbon transport and transformation

    NASA Astrophysics Data System (ADS)

    Gabrielsen, P. J.; Wilson, J. L.; Pullin, M.

    2011-12-01

    Dissolved organic carbon (DOC) is a complex suite of organic compounds present in natural ecosystems, and is particularly studied in river and stream systems. The hyporheic zone (HZ), a region of surface water-shallow groundwater exchange, has been identified as a hotspot of DOC processing and is generally regarded as a net sink of organic matter. More recent studies into stream DOC have shifted to examining DOC quality rather than bulk quantity. DOC quality variability has been linked to hydrologic and climatic variability, both focuses of current climate change research. A new agent-based model in the NetLogo modeling environment couples hydrologic transport with chemical and biological transformation of DOC to simulate changing DOC quality in hyporheic flow. A pore-scale model implements a Lattice Boltzmann fluid dynamic model and surficial interactions to simulate sorption and microbial uptake. Upscaled to a stream meander scale, this model displays spatial variation and evolution of DOC quality. Model output metrics are correlated to field sample analytical results from a hyporheic meander of the East Fork Jemez River, Sandoval Co., NM.

  15. Effects of asynchronous snowmelt on flushing of dissolved organic carbon: A mixing model approach

    USGS Publications Warehouse

    Boyer, E.W.; Hornberger, G.M.; Bencala, K.E.; McKnight, Diane M.

    2000-01-01

    In many snowmelt-dominated catchments, stream dissolved organic carbon (DOC) levels typically increase rapidly as spring melt commences, peak before maximum discharge, and decrease quickly as melting continues. We present data from Deer Creek (Summit County, CO) that shows this distinctive flushing response of DOC during snowmelt runoff, with DOC stored in landscape soils flushed to the stream in response to infiltrating melt waters. Our prior studies show that asynchronous melting of the snowpack across the landscape causes the spring DOC flush to be initiated at different times throughout the catchment. In this study we quantify characteristics of the asynchronous melt and its effect on DOC flushing. We investigated whether a simple mixing model can be used to capture the essentials of the asynchronous melting of a seasonal snowpack and its controls on DOC transport. We divided the catchment into zones of aspect and elevation, which largely determine spatial and temporal variations in the distribution of snow. TOPMODEL was used to simulate the hydrology in each zone, and the simulated flow paths were routed through a simple DOC mixing model to predict contributions of DOC to the stream. The zonal responses were aggregated to give a predicted response of hydrology and DOC fluxes for the entire catchment. Our results indicate that asynchronous melting-which determines the timing of contributions of discharge and DOC to streamflow from different areas of the landscape-can be quantified using a simple modeling approach. Copyright ?? 2000 John Wiley & Sons, Ltd.

  16. SLUDGE BATCH 6/TANK 40 SIMULANT CHEMICAL PROCESS CELL SIMULATIONS

    SciTech Connect

    Koopman, David

    2010-04-28

    , and significant mercury was not accounted for in the highest acid run. Coalescence of elemental mercury droplets in the mercury water wash tank (MWWT) appeared to degrade with increasing stoichiometry. Observations were made of mercury scale formation in the SRAT condenser and MWWT. A tacky mercury amalgam with Rh, Pd, and Cu, plus some Ru and Ca formed on the impeller at 159% acid. It contained a significant fraction of the available Pd, Cu, and Rh as well as about 25% of the total mercury charged. Free (elemental) mercury was found in all of the SME products. Ammonia scrubbers were used during the tests to capture off-gas ammonia for material balance purposes. Significant ammonium ion formation was again observed during the SRAT cycle, and ammonia gas entered the off-gas as the pH rose during boiling. Ammonium ion production was lower than in the SB6 Phase II and the qualification simulant testing. Similar ammonium ion formation was seen in the ARP/MCU simulation as in the 120% flowsheet run. A slightly higher pH caused most of the ammonium to vaporize and collect in the ammonia scrubber reflux solution. Two periods of foaminess were noted. Neither required additional antifoam to control the foam growth. A steady foam layer formed during reflux in the 120% acid run. It was about an inch thick, but was 2-3 times more volume of bubbles than is typically seen during reflux. A similar foam layer also was seen during caustic boiling of the simulant during the ARP addition. While frequently seen with the radioactive sludge, foaminess during caustic boiling with simulants has been relatively rare. Two further flowsheet tests were performed and will be documented separately. One test was to evaluate the impact of process conditions that match current DWPF operation (lower rates). The second test was to evaluate the impact of SRAT/SME processing on the rheology of a modified Phase III simulant that had been made five times more viscous using ultrasonication.

  17. Model-aided quantification of dissolved carbon and nitrogen release after windthrow disturbance in an Austrian karst system

    NASA Astrophysics Data System (ADS)

    Hartmann, A.; Kobler, J.; Kralik, M.; Dirnböck, T.; Humer, F.; Weiler, M.

    2016-01-01

    Karst systems are important for drinking water supply. Future climate projections indicate increasing temperature and a higher frequency of strong weather events. Both will influence the availability and quality of water provided from karst regions. Forest disturbances such as windthrow can disrupt ecosystem cycles and cause pronounced nutrient losses from the ecosystems. In this study, we consider the time period before and after the wind disturbance period (2007/08) to identify impacts on DIN (dissolved inorganic nitrogen) and DOC (dissolved organic carbon) with a process-based flow and solute transport simulation model. When calibrated and validated before the disturbance, the model disregards the forest disturbance and its consequences on DIN and DOC production and leaching. It can therefore be used as a baseline for the undisturbed system and as a tool for the quantification of additional nutrient production. Our results indicate that the forest disturbance by windthrow results in a significant increase of DIN production lasting ˜ 3.7 years and exceeding the pre-disturbance average by 2.7 kg ha-1 a-1 corresponding to an increase of 53 %. There were no significant changes in DOC concentrations. With simulated transit time distributions we show that the impact on DIN travels through the hydrological system within some months. However, a small fraction of the system outflow (< 5 %) exceeds mean transit times of > 1 year.

  18. Characterization of dissolved organic matter from a restored urban marsh and its role in the mobilization of trace metals.

    PubMed

    ElBishlawi, Hagar; Jaffe, Peter R

    2015-05-01

    Dissolved organic matter (DOM), although highly variable and not very well characterized, plays a role in many important environmental reaction and transport processes, including trace metal mobilization. This study characterizes heterogeneous DOM from the pore-water of a restored urban tidal marsh, using chemical, optical, and electrochemical methods for dissolved organic carbon/nitrogen ratios (C:N: 1.8-6.4), spectroscopic characteristics (decreased aromaticity in amended sediments), element ratios (maximum sediment-associated trace metal concentrations measured<30 cm), and metal complexation properties (logKc: Cd: 10.7±0.7>Pb: 9.5±0.1>Cr: 7.3±0.1>Cu: 5.07±0.53), all as a function of sediment depth. Specific DOM properties from the restored marsh were then compared to pore-water samples from a natural marsh and a simulated wetland microcosm which resulted in similar values, while the reference humic acid significantly differed in properties from field DOM. The results revealed that reference humic acids do not accurately represent the complexity of natural heterogeneous DOM, whereas a simulated wetland microcosm may provide a reasonable representation of natural DOM. Clear differences between amended and original soil (transition below 30 cm) were observed in DOM and trace metal properties including: lower DOM content, higher logKc values, less DOM complexity, development of a iron-sulfide redox buffering pool, and greater affinity for metals in the solid phase occurring in the amended sediments. PMID:25681788

  19. Release of dissolved nitrogen from water during depressurization

    NASA Technical Reports Server (NTRS)

    Simoneau, R. J.

    1978-01-01

    Experiments were run to study depressurization of water containing various concentrations of dissolved nitrogen gas, the primary case being room temperature water saturated with nitrogen at 4 MPa. In a static depressurization experiment, water with very high nitrogen content was depressurized at rates from 0.09 to 0.50 MPa per second and photographed with high speed movies. The pictures showed that the bubble population at a given pressure increased strongly with decreasing depressurization rate. Flow experiments were performed in an axisymmetric converging-diverging nozzle and in a two-dimensional converging nozzle with glass sidewalls. Depressurization gradients were roughly 500 to 1200 MPa per second. Both nozzles exhibited choked flow behavior even at nitrogen concentration levels as low as 4 percent of saturated. The flow rates were independent of concentration level and could be computed as incompressible water flow based on the difference between stagnation and throat pressures; however, the throat pressures were significantly different between the two nozzles.

  20. Radiocarbon in dissolved organic carbon of the Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Druffel, E. R. M.; Griffin, S.; Coppola, A. I.; Walker, B. D.

    2016-05-01

    Marine dissolved organic carbon (DOC) is produced in the surface ocean though its radiocarbon (14C) age in the deep ocean is thousands of years old. Here we show that ≥10% of the DOC in the deep North Atlantic is of postbomb origin and that the 14C age of the prebomb DOC is ≥4900 14C year, ~900 14C year older than previous estimates. We report 14C ages of DOC in the deep South Atlantic that are intermediate between values in the North Atlantic and the Southern Ocean. Finally, we conclude that prebomb DOC 14C ages are older and a portion of deep DOC is more dynamic than previously reported.