Sample records for simulated dissolver off-gas

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

    SciTech Connect

    Jubin, Robert Thomas [ORNL

    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.

  2. 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.

  3. 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

    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 de-coupled 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 canistered glass waste forms. This LAW Off-Gas Condensate stream contains components that are volatile at melter temperatures and are problematic for the glass waste form. Because this stream recycles within WTP, these components accumulate in the Condensate stream, exacerbating their impact on the number of LAW glass containers that must be produced. Approximately 32% of the sodium in Supplemental LAW comes from glass formers used to make the extra glass to dilute the halides to be within acceptable concentration ranges in the LAW glass. Diverting the stream reduces the halides in the recycled Condensate and is a key outcome of this work. Additionally, under possible scenarios where the LAW vitrification facility commences operation prior to the WTP Pretreatment facility, identifying a disposition path becomes vitally important. This task examines the impact of potential future disposition of this stream in the Hanford tank farms, and investigates auxiliary evaporation to enable another disposition path. Unless an auxiliary evaporator is used, returning the stream to the tank farms would require evaporation in the 242-A evaporator. This stream is expected to be unusual because it will be very high in corrosive species that are volatile in the melter (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 used for routine evaluation of feed compatibility studies for the 242-A evaporator. One of the

  4. 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

    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 de-coupled 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. This LAW Off-Gas Condensate stream contains components that are volatile at melter temperatures and are problematic for the glass waste form. Because this stream recycles within WTP, these components accumulate in the Condensate stream, exacerbating their impact on the number of LAW glass containers that must be produced. Approximately 32% of the sodium in Supplemental LAW comes from glass formers used to make the extra glass to dilute the halides to acceptable concentrations in the LAW glass, and diverting the stream reduces the halides in the recycled Condensate and is a key outcome of this work. Additionally, under possible scenarios where the LAW vitrification facility commences operation prior to the WTP Pretreatment facility, identifying a disposition path becomes vitally important. This task examines the potential treatment of this stream to remove radionuclides and subsequently disposition the decontaminated stream elsewhere, such as the Effluent Treatment Facility (ETF), for example. The treatment process envisioned is very similar to that used for the Actinide Removal Process (ARP) that has been operating for years at the Savannah River Site (SRS), and focuses on using mature radionuclide removal technologies that are also 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 to the insoluble technetium dioxide. The reducing agents were tried with and without sorbents.

  5. A system of miniaturized stirred bioreactors for parallel continuous cultivation of yeast with online measurement of dissolved oxygen and off-gas.

    PubMed

    Klein, Tobias; Schneider, Konstantin; Heinzle, Elmar

    2013-02-01

    Chemostat cultivation is a powerful tool for physiological studies of microorganisms. We report the construction and application of a set of eight parallel small-scale bioreactors with a working volume of 10?mL for continuous cultivation. Hungate tubes were used as culture vessels connected to multichannel-peristaltic pumps for feeding fresh media and removal of culture broth and off-gas. Water saturated air is sucked into the bioreactors by applying negative pressure, and small stirrer bars inside the culture vessels allow sufficient mixing and oxygen transfer. Optical sensors are used for non-invasive online measurement of dissolved oxygen, which proved to be a powerful indicator of the physiological state of the cultures, particularly of steady-state conditions. Analysis of culture exhaust-gas by means of mass spectrometry enables balancing of carbon. The capacity of the developed small-scale bioreactor system was validated using the fission yeast Schizosaccharomyces pombe, focusing on the metabolic shift from respiratory to respiro-fermentative metabolism, as well as studies on consumption of different substrates such as glucose, fructose, and gluconate. In all cases, an almost completely closed carbon balance was obtained proving the reliability of the experimental setup. PMID:22887039

  6. 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

    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 de-coupled 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. This LAW Off-Gas Condensate stream contains components that are volatile at melter temperatures and are problematic for the glass waste form. Because this stream recycles within WTP, these components accumulate in the Condensate stream, exacerbating their impact on the number of LAW glass containers that must be produced. Approximately 32% of the sodium in Supplemental LAW comes from glass formers used to make the extra glass to dilute the halides to acceptable concentrations in the LAW glass, and diverting the stream reduces the halides in the recycled Condensate and is a key outcome of this work. Additionally, under possible scenarios where the LAW vitrification facility commences operation prior to the WTP Pretreatment facility, identifying a disposition path becomes vitally important. This task seeks to examine the potential treatment of this stream to remove radionuclides and subsequently disposition the decontaminated stream elsewhere, such as the Effluent Treatment Facility (ETF), for example. The treatment process envisioned is very similar to that used for the Actinide Removal Process (ARP) that has been operating for years at the Savannah River Site (SRS), and focuses on using mature radionuclide removal technologies that are also 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 effective at alkaline pH. Conversely, removal of the cesium was more effective at alka

  7. Surface decontamination of simulated chemical warfare agents using a nonequilibrium plasma with off-gas monitoring

    Microsoft Academic Search

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

    2002-01-01

    InnovaTek, Inc., Richland, WA, is developing a surface decontamination technology that utilizes active species generated in a nonequilibrium corona plasma. The plasma technology was tested against dimethyl-methyl phosphonate (DMMP), a simulant for the chemical agent Sarin. Gas chromatograph mass spectrometry analysis showed that a greater than four log10 destruction of the DMMP on an aluminum surface was achieved in a

  8. DYNAMIC SIMULATION FOR IMPROVING THE PERFORMANCE OF BOIL-OFF GAS RECONDENSATION SYSTEM AT LNG RECEIVING TERMINALS

    Microsoft Academic Search

    Yajun Li; Xingshui Chen

    2012-01-01

    The boil-off gas (BOG) recondensation system is one of the most important facilities at liquefied natural gas (LNG) storing and receiving terminals, whose failure may cause BOG loss and\\/or severe accidents. Operation of a BOG recondensation system requires sufficient care under various situations, especially when LNG load and BOG load fluctuate. This study improves the control algorithm for a BOG

  9. Efficient particulate scrubber for glass melter off-gas

    SciTech Connect

    Wright, G.T.

    1983-01-01

    Operation of joule-heated, continuous slurry-fed melters has demonstrated that off-gas aerosols are generated by entrainment of feed slurry and vaporization of volatile species from the melt. Effective off-gas stream decontamination for these aerosols can be obtained by utilizing a suitably designed and operated wet scrubber system. Results are presented for performance tests conducted with an air aspirating-type venturi scrubber processing a simulated melter off-gas aerosol. Mass overall removal efficiencies ranged from 99.5 to 99.8%. Details of the testing program and applications for melter off-gas system design are discussed.

  10. Efficient particulate scrubber for glass melter off-gas

    SciTech Connect

    Wright, G.T.

    1982-01-01

    Operation of joule-heated, continuous slurry fed melters has demonstrated that off-gas aerosols are generated by entrainment of feed slurry and vaporization of volatile species from the melt. Effective off-gas stream decontamination for these aerosols can be obtained by utilizing a suitably designed and operated wet scrubber system. Results are presented for performance tests conducted with an air aspirating-type venturi scrubber processing a simulated melter off-gas aerosol. Mass removal efficiencies ranged from 99.5 to 99.8%. Details of the testing program and applications for melter off-gas system design are discussed.

  11. 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

    The operational requirements for the River Protection Project - Waste Treatment Plant (RPP-WTP) Low Activity Waste (LAW) and High Level Waste (HLW) melter systems, together with the feed constituents, impose a number of challenges to the off-gas treatment system. The system must be robust from the standpoints of operational reliability and minimization of maintenance. The system must effectively control and remove a wide range of solid particulate matter, acid mists and gases, and organic constituents (including those arising from products of incomplete combustion of sugar and organics in the feed) to concentration levels below those imposed by regulatory requirements. The baseline design for the RPP-WTP LAW primary off-gas system includes a submerged bed scrubber (SBS), a wet electrostatic precipitator (WESP), and a high efficiency particulate air (HEPA) filter. The secondary off-gas system includes a sulfur-impregnated activated carbon bed (AC-S), a thermal catalytic oxidizer (TCO), a single-stage selective catalytic reduction NOx treatment system (SCR), and a packed-bed caustic scrubber (PBS). The baseline design for the RPP-WTP HLW primary off-gas system includes an SBS, a WESP, a high efficiency mist eliminator (HEME), and a HEPA filter. The HLW secondary off-gas system includes a sulfur-impregnated activated carbon bed, a silver mordenite bed, a TCO, and a single-stage SCR. The one-third scale HLW DM1200 Pilot Melter installed at the Vitreous State Laboratory (VSL) was equipped with a prototypical off-gas train to meet the needs for testing and confirmation of the performance of the baseline off-gas system design. Various modifications have been made to the DM1200 system as the details of the WTP design have evolved, including the installation of a silver mordenite column and an AC-S column for testing on a slipstream of the off-gas flow; the installation of a full-flow AC-S bed for the present tests was completed prior to initiation of testing. The DM1200 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 response to attainable plenum temperatures as well as temperature increases in the sulfur impr

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

    SciTech Connect

    Choi, A.S. [Westinghouse Savannah River Company, AIKEN, SC (United States); 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

  13. 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...

  14. 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.

  15. Experimental simulation of solids distribution in coal liquefaction dissolvers

    Microsoft Academic Search

    R. Sivasubramanian; D. H. S. Ying; E. N. Givens

    1981-01-01

    A major element of the coal dissolution section of any liquefaction plant is the dissolver. The design of the SRC-I Demonstration Plant Dissolver planned for Western Kentucky based on data generated from the Wilsonville and Ft. Lewis dissolvers is discussed. Two different columns of 127 mm (5 inch) and 305 mm (12 inch) diameters were used to investigate the effect

  16. Numerical simulation of dissolved silica in the San Fancisco Bay

    USGS Publications Warehouse

    Peterson, D.H.; Festa, J.F.; Conomos, T.J.

    1978-01-01

    A two-dimensional (vertical) steady-state numerical model that simulates water circulation and dissolved-silica distributions is applied to northern San Francisco Bay. The model (1) describes the strong influence of river inflow on estuarine circulation and, in turn, on the biologically modulated silica concentration, and (2) shows how rates of silica uptake relate to silica supply and mixing rates in modifying a conservative behavior. Longitudinal silica distributions influenced by biological uptake (assuming both vertically uniform and vertically decreasing uptake situations) show that uptake rates of 1 to 10 ??g-at. l-1 day-1 are sufficient to depress silica concentrations at river inflows of 100-400 m3 s-1, respectively, and that the higher rates appear ineffective at inflows above 400 m3 s-1. The simulations further indicate that higher silica utilization in the null zone is not essential to depress silica concentrations strongly there. Advective water-replacement times at river inflows of 400, 200 and 100 m3 s-1 are computed to be less than 25, 45 and 75 days, respectively, for a 120-km estuary-river system. ?? 1978.

  17. 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.

  18. COUPLED FREE AND DISSOLVED PHASE TRANSPORT: NEW SIMULATION CAPABILITIES AND PARAMETER INVERSION

    EPA Science Inventory

    The vadose zone free-phase simulation capabilities of the US EPA Hydrocarbon Spill Screening Model (HSSM)have been linked with the 3-D multi-species dissolved-phase contaminant transport simulator MT3DMS....

  19. Off-gas characteristics of liquid-fed joule-heated ceramic melters

    Microsoft Academic Search

    R. W. Goles; G. J. Sevigny

    1982-01-01

    The off gas characteristics of liquid fed joule heated ceramic meters were investigated as a function of melter operational condition and simulated waste feed composition. The identity and behavior patterns of gaseous emissions, the characteristics of melter generated aerosols, the nature and magnitude of melter effluent losses and the factors affecting melter operational performance were established.

  20. Off-gas characteristics of liquid-fed joule-heated ceramic melters

    NASA Astrophysics Data System (ADS)

    Goles, R. W.; Sevigny, G. J.

    1982-06-01

    The off gas characteristics of liquid fed joule heated ceramic meters were investigated as a function of melter operational condition and simulated waste feed composition. The identity and behavior patterns of gaseous emissions, the characteristics of melter generated aerosols, the nature and magnitude of melter effluent losses and the factors affecting melter operational performance were established.

  1. 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 lift up the dissolver basket for the agitator speeds up to 2500 rpm. The results also show that local velocity magnitudes for the three-blade flat plate agitator are at maximum three times smaller than the helical fourblade one. Table 5 and Table 6 summarize the results.

  2. 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...

  3. 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.

  4. 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...

  5. 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

  6. Diel flux of dissolved carbohydrate in a salt marsh and a simulated estuarine ecosystem

    Microsoft Academic Search

    C. M. Burney; K. M. Johnson; J. Mc N. Sieburth

    1981-01-01

    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 m3 seawater tank simulating an estuarine ecosystem. Their patterns are compared to those for total dissolved organic carbon (DOC), SCO2, pH, O2, chlorophyll a, phaeopigments and solar radiation. During 5 of the

  7. COUPLED FREE AND DISSOLVED PHASE TRANSPORT: NEW SIMULATION CAPABILITIES AND PARAMETER INVERSION

    EPA Science Inventory

    The vadose zone free-phase simulation capabilities of the US EPA Hydrocarbon Spill Screening Model (HSSM) (Weaver et al., 1994) have been linked with the 3-D multi-species dissolved-phase contaminant transport simulator MT3DMS (Zheng and Wang, 1999; Zheng, 2005). The linkage pro...

  8. Simulated changes in dissolved Iron deposition to the global ocean driven by human activity

    NASA Astrophysics Data System (ADS)

    Myriokefalitakis, Stelios; Daskalakis, Nikos; Mihalopoulos, Nikos; Baker, Alex R.; Nenes, Athanassios; Kanakidou, Maria

    2015-04-01

    The global 3-d chemistry transport atmospheric model TM4-ECPL is used to simulate the atmospheric cycle of iron (Fe) and evaluate its atmospheric deposition to the ocean by accounting for both Fe natural and anthropogenic sources as well as of the proton and ligand promoted iron mobilisation from dust aerosol. Model evaluation is performed by comparison to available observations. Present day dissolved Fe deposition presents strong spatial and temporal variability with an annual deposition flux about 0.489 Tg(Fe)/yr from which about 25% are deposited over the ocean. The model simulates past, present and future iron deposition accounting for changes in anthropogenic emissions. We show that dissolved iron deposition has significantly increased since 1850 while it is expected to decrease in the future due to air pollution regulations. These changes affect the atmospheric dissolved Fe supply to High-Nutrient-Low-Chlorophyll oceanic areas characterized by Fe scarcity.

  9. 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 ...

  10. Simulated climate change effects on dissolved oxygen characteristics in ice-covered lakes

    Microsoft Academic Search

    Xing Fang; Heinz G. Stefan

    1997-01-01

    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 area (AS), maximum depth (HMAX), and Secchi depth as a measure of light attenuation and trophic state. The model is

  11. 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.

  12. Materials performance in off-gas systems containing iodine

    Microsoft Academic Search

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

    1981-01-01

    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

  13. RELIABLE OZONE DISINFECTION USING OFF-GAS CONTROL

    EPA Science Inventory

    The electrical energy used in manufacturing ozone constitutes a major part of the operating cost of disinfection. The paper presents a control strategy that combines use of off-gas measurement and contact time to achieve reliable disinfection throughout the day with minimum energ...

  14. 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)

  15. 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.

  16. 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.

  17. One-dimensional simulation of stratification and dissolved oxygen in McCook Reservoir, Illinois

    USGS Publications Warehouse

    Robertson, Dale M.

    2000-01-01

    As part of the Chicagoland Underflow Plan/Tunnel and Reservoir Plan, the U.S. Army Corps of Engineers, Chicago District, plans to build McCook Reservoir.a flood-control reservoir to store combined stormwater and raw sewage (combined sewage). To prevent the combined sewage in the reservoir from becoming anoxic and producing hydrogen sulfide gas, a coarse-bubble aeration system will be designed and installed on the basis of results from CUP 0-D, a zero-dimensional model, and MAC3D, a three-dimensional model. Two inherent assumptions in the application of MAC3D are that density stratification in the simulated water body is minimal or not present and that surface heat transfers are unimportant and, therefore, may be neglected. To test these assumptions, the previously tested, one-dimensional Dynamic Lake Model (DLM) was used to simulate changes in temperature and dissolved oxygen in the reservoir after a 1-in-100-year event. Results from model simulations indicate that the assumptions made in MAC3D application are valid as long as the aeration system, with an air-flow rate of 1.2 cubic meters per second or more, is operated while the combined sewage is stored in the reservoir. Results also indicate that the high biochemical oxygen demand of the combined sewage will quickly consume the dissolved oxygen stored in the reservoir and the dissolved oxygen transferred through the surface of the reservoir; therefore, oxygen must be supplied by either the rising bubbles of the aeration system (a process not incorporated in DLM) or some other technique to prevent anoxia.

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

    DOEpatents

    Wright, George T. (15 Cherry Hills Dr., Aiken, SC 29803)

    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. Glass melter off-gas system pluggages: Cause, significance, and remediation

    SciTech Connect

    Jantzen, C.M.

    1991-03-01

    Liquid high-level nuclear waste will be immobilized at the Savannah River Site (SRS) by vitrification in borosilicate glass. The glass will be produced in the Defense Waste Processing Facility (DWPF) where the glass will be poured into stainless steel canisters for eventual disposal in a geologic repository. Experimental glass melters used to develop the vitrification process for immobilization of the waste have experienced problems with pluggage of the off-gas line with solid deposits. Off-gas deposits from the DWPF 1/2 Scale Glass Melter (SGM) and the 1/10th scale Integrated DWPF Melter System (IDMS) were determined to be mixtures of alkali rich chlorides, sulfates, borates, and fluorides with entrained Fe{sub 2}O{sub 3}, spinel, and frit particles. The distribution and location of the alkali deposits throughout the off-gas system indicate that the deposits form by vapor-phase transport and condensation. Condensation of the alkali-rich phases cement the entrained particulates causing off-gas system pluggages. The identification of vapor phase transport as the operational mechanism causing off-gas system pluggage indicates that deposition can be effectively eliminated by increasing the off-gas velocity. Scale glass melter operating experience indicates that a velocity of >50 fps is necessary in order to transport the volatile species to the quencher to prevent having condensation occur in the off-gas line. Hotter off-gas line temperatures would retain the alkali compounds as vapors so that they would remain volatile until they reach the quencher. However, hotter off-gas temperatures can only be achieved by using less air/steam flow at the off-gas entrance, e.g. at the off-gas film cooler (OGFC). This would result in lower off-gas velocities. Maintaining a high velocity is, therefore, considered to be a more important criterion for controlling off-gas pluggage than temperature control. 40 refs., 16 figs., 5 tabs.

  20. Thermal Expansion of Simulated Fuels with Dissolved Fission Products in a UO2 Matrix

    NASA Astrophysics Data System (ADS)

    Kang, K. H.; Na, S. H.; Park, C. J.; Kim, Y. H.; Song, K. C.; Lee, S. H.; Kim, S. W.

    2009-06-01

    As a part of the DUPIC (direct use of spent PWR fuel in CANDU reactors) fuel development program, the thermal expansion of simulated spent fuel pellets with dissolved fission products has been studied by using a thermo-mechanical analyzer (TMA) in the temperature range from 298 K to 1773 K to investigate the effects of fission products forming solid solutions in a UO2 matrix on the thermal expansions. Simulated fuels with an equivalent burn-up of (30 to 120) GWd/tU were used in this study. The linear thermal expansions of the simulated fuel pellets were higher than that of UO2, and the difference between these fuel pellets and UO2 increased monotonically with temperature. For the temperature range from 298 K to 1773 K, the values of the average linear thermal expansion coefficients for UO2 and simulated fuels with an equivalent burn-up of (30, 60, and 120) GWd/tU are 1.19 × 10-5 K-1, 1.22 × 10-5 K-1, 1.26 × 10-5 K-1, and 1.32 × 10-5 K-1, respectively.

  1. Watershed modeling of dissolved oxygen and biochemical oxygen demand using a hydrological simulation Fortran program.

    PubMed

    Liu, Zhijun; Kieffer, Janna M; Kingery, William L; Huddleston, David H; Hossain, Faisal

    2007-11-01

    Several inland water bodies in the St. Louis Bay watershed have been identified as being potentially impaired due to low level of dissolved oxygen (DO). In order to calculate the total maximum daily loads (TMDL), a standard watershed model supported by U.S. Environmental Protection Agency, Hydrological Simulation Program Fortran (HSPF), was used to simulate water temperature, DO, and bio-chemical oxygen demand (BOD). Both point and non-point sources of BOD were included in watershed modeling. The developed model was calibrated at two time periods: 1978 to 1986 and 2000 to 2001 with simulated DO closely matched the observed data and captured the seasonal variations. The model represented the general trend and average condition of observed BOD. Water temperature and BOD decay are the major factors that affect DO simulation, whereas nutrient processes, including nitrification, denitrification, and phytoplankton cycle, have slight impacts. The calibrated water quality model provides a representative linkage between the sources of BOD and in-stream DO\\BOD concentrations. The developed input parameters in this research could be extended to similar coastal watersheds for TMDL determination and Best Management Practice (BMP) evaluation. PMID:17990165

  2. Accepted for publication in GEOPHYSICAL RESEARCH LETTERS, doi:10.1029/2010GL044689 1/10 Simulations of underwater plumes of dissolved

    E-print Network

    of underwater plumes of dissolved oil in the Gulf of Mexico Alistair Adcroft12 , Robert Hallberg23 , John P of underwater plumes of dissolved oil in the Gulf of Mexico, Geophys. Res. Lett., doi:10.1029/2010GL044689 is embedded in an ocean- climate model and used to simulate underwater plumes of dissolved and suspended oil

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

    Microsoft Academic Search

    Fellinger

    2005-01-01

    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.

  4. Inorganic adsorber material for off-gas cleaning in fuel reprocessing plants

    Microsoft Academic Search

    J. G. Wilhelm; H. Schuettelkopf; M. W. First

    1973-01-01

    USA (28 Aug 1972). impregnated, amorphous silicic acid was developed for ; use in off-gas cleaning systems of fuel reprocessing plants. Extensive ; experimental work was performed to evaluate the removal efficiency of this ; material from off-gas containing NOâ for elemental iodine and methyl iodide. ; Experimental data are given on the influence exerted by relative humidity ; temperature,

  5. A plasma process controlled emissions off-gas demonstration

    SciTech Connect

    Battleson, D.; Kujawa, S.T. [MSE, Inc., Butte, MT (United States); Leatherman, G. [SAIC, Inc., Idaho Falls, ID (United States). STAR Center

    1995-12-31

    Thermal technologies are currently identified as playing an important role in the treatment of many DOE waste streams, and emissions from these processes will be scrutinized by the public, regulators, and stakeholders. For some time, there has been a hesitancy by the public to accept thermal treatment of radioactive contaminated waste because of the emissions from these processes. While the technology for treatment of emissions from these processes is well established, it is not possible to provide the public complete assurance that the system will be in compliance with air quality regulations 100% of the operating time in relation to allowing noncompliant emissions to exit the system. Because of the possibility of noncompliant emissions and the public`s concern over thermal treatment systems, it has been decided that the concept of a completely controlled emissions off-gas system should be developed and implemented on Department of Energy (DOE) thermal treatment systems. While the law of conservation of mass precludes a completely closed cycle system, it is possible to apply the complete control concept to emissions.

  6. TREATMENT OF MERCURY TARGET OFF-GAS AT SNS

    SciTech Connect

    DeVore, Joe R [ORNL; Freeman, David W [ORNL

    2007-01-01

    The Spallation Neutron Source (SNS) is the first operational spallation source to use liquid Mercury as a target material. This paper describes the treatment system to remove volatile spallation products from a Helium purge stream that emanates from the Mercury target and adjustments made to achieve design goals in response to phenomena experienced during initial operations. The Helium stream is treated to remove volatile spallation products prior to environmental release because of its activity level as these accumulate in the gas space in the Mercury Loop. Unanticipated local dose rates were noted in treatment system components during low power startup. Gamma scanning of these components identified the presence of nineteen noble gas isotopes and their daughters, indicating that the doses resulted from noble gas sorption. Treatment of this equipment with stable Xenon greatly reduced but did not eliminate these. Significant moisture was also encountered in the system, resulting in the plugging of the system cold trap. Changes to some of the system equipment were required together with moisture elimination from components to which moisture was sorbed. Necessary re-configuration of Mercury pump components presented additional requirements and system control changes to accommodate system operation at reduced pressure. The Off-Gas Treatment System has been successfully operated since April, 2006. System availability and removal effectiveness have been high. Operational issues occurring during the first year of operation have been resolved.

  7. Stimulating hydrogenotrophic denitrification in simulated groundwater containing high dissolved oxygen and nitrate concentrations.

    PubMed

    Schnobrich, Matthew R; Chaplin, Brian P; Semmens, Michael J; Novak, Paige J

    2007-05-01

    In agricultural areas, nitrate (NO3-) is a common groundwater pollutant as a result of extensive fertilizer application. At elevated concentrations, NO3- consumption causes methemoglobinemia in infants and has been linked to several cancers; therefore, its removal from groundwater is important. The addition of hydrogen gas (H2) via gas-permeable membranes has been shown to stimulate denitrification in a laboratory-scale reactor. This research, using large columns packed with aquifer material to which a simulated groundwater was fed, was conducted to further identify the conditions required for the use of membrane-delivered H2 in situ. In this study, we show that this novel technology was capable of treating highly contaminated (25 mg/L NO3- -N) and oxygenated (5.5mg/L dissolved oxygen) water, but that nutrient addition and gas pressure adjustment was required. Complete NO3- reduction was possible without the accumulation of either NO2- or N2O when the H2 lumen pressure was increased to 17 psi and phosphate was added to the groundwater. The total organic carbon content of the effluent, 110 cm downgradient of H2 addition, did not increase. The results from these experiments demonstrate that this technology can be optimized to provide effective NO3- removal in even challenging field applications. PMID:17363026

  8. Observing system simulation experiments of dissolved oxygen monitoring in Massachusetts Bay

    NASA Astrophysics Data System (ADS)

    Xue, Pengfei; Chen, Changsheng; Beardsley, Robert C.

    2012-05-01

    Observing system simulation experiments (OSSEs) were performed in Massachusetts Bay for the design of optimal monitoring sites for dissolved oxygen (DO) measurements. Experiments were carried out using the Ensemble Kalman Filter (EnKF) for data assimilation with focus on initial and boundary perturbations. Running a well-validated water quality model with a perturbed initial field of DO but "true" boundary forcing conditions, the model is capable of restoring DO back to the true state without data assimilation over a recovery time scale of about a month. Since DO in Massachusetts Bay has a bay-wide correlation scale, placing a monitoring site of DO near the northern boundary or at a location that has maximum correlation to the entire domain can shorten the restoring time to a week. Running the model with perturbed boundary forcing without data assimilation, the results show that the errors propagate into Massachusetts Bay following the inflow from the northern boundary and spread southward to Cape Cod Bay over a time scale of about a month. Using a DO monitoring site located near the northern entrance, the data assimilation can efficiently control the error propagation and prevent the model field from deviating from the true state. The model shows that the inflow from the northern entrance, which is connected to the upstream Western Maine Coastal Current, plays an important role in controlling the DO variation in Massachusetts Bay, and the residence time of the bay controlled by this flow is about one month. Understanding the upstream boundary-control nature of this system is critical for optimal design of sampling strategies of water quality variables in this region.

  9. The use of a biofilter for reducing off-gas odour from an industrial fermentation process.

    PubMed

    Searcy, E M L; Zhang, Q; Cicek, N

    2005-01-01

    This study evaluated the performance of a lab-scale, closed bed biofilter for the removal of odour in off-gas released from an industrial fermentation facility. This off-gas was emitted from the facility periodically after the sterilization of fermentation medium. The lab scale biofilter was operated for over two months, totalling 30 medium sterilizations. The biofilter was subjected to a shock odour load for each sterilization cycle and to two airflow conditions: the fermentation off-gas and compressed room air, which was cooler and drier than the fermentation off-gas. The biofilter was effective in removing odour under shock loading and variable operating conditions (temperature and relative humidity). An odour reduction rate of 72% was achieved immediately after medium sterilization when odour levels were highest (32 800 OU m(-3)). The filter had an odour removal efficiency of 61% and 67% for 24 h and 50 h after sterilization, respectively. PMID:15747605

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

    DOEpatents

    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. Glass melter off-gas system pluggages: Cause, significance, and remediation

    SciTech Connect

    Jantzen, C.M.

    1991-12-31

    Liquid high-level nuclear waste will be immobilized at the Savannah River Site (SRS) by vitrification in borosilicate glass. Experimental glass melters, used to develop the vitrification process, have occasionally experienced problems with pluggage of the off-gas line with solid deposits. The deposits were determined to be mixtures of alkali rich chlorides, sulfates, borates, and fluorides with entrained insoluble particles of Fe{sub 2}O{sub 3} spinel, and frit. The distribution and location of the alkali deposits throughout the off-gas system indicate that the deposits form by vapor-phase transport and condensation. Condensation of the alkali-rich phases cements the entrained particulates causing the off-gas system pluggages. The identification of vapor phase transport as the operational mechanism causing off-gas system pluggages indicates that deposition can be effectively eliminated by increasing the off-gas velocity. The cementitious alkali borates, halides, and sulfates comprising the off-gas line deposits were determined to be water soluble. Thus pluggage can be effectively removed with water and/or steam.

  12. Glass melter off-gas system pluggages: Cause, significance, and remediation

    SciTech Connect

    Jantzen, C.M.

    1991-01-01

    Liquid high-level nuclear waste will be immobilized at the Savannah River Site (SRS) by vitrification in borosilicate glass. Experimental glass melters, used to develop the vitrification process, have occasionally experienced problems with pluggage of the off-gas line with solid deposits. The deposits were determined to be mixtures of alkali rich chlorides, sulfates, borates, and fluorides with entrained insoluble particles of Fe{sub 2}O{sub 3} spinel, and frit. The distribution and location of the alkali deposits throughout the off-gas system indicate that the deposits form by vapor-phase transport and condensation. Condensation of the alkali-rich phases cements the entrained particulates causing the off-gas system pluggages. The identification of vapor phase transport as the operational mechanism causing off-gas system pluggages indicates that deposition can be effectively eliminated by increasing the off-gas velocity. The cementitious alkali borates, halides, and sulfates comprising the off-gas line deposits were determined to be water soluble. Thus pluggage can be effectively removed with water and/or steam.

  13. 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 permeability of the system was calculated to be 2.2-2.5 x 10-9 m2, and this used for modelling work. Having experimentally reproduced the transition from diffusion-dissolution to convection-dissolution, and from this determined the system properties, we simulated the process in a numerical flow model. A high resolution model of the Hele-Shaw cell was built using the TOUGH2 flow simulator with the ECO 2N fluid property module, with a permeability of 2.5 x 10-9 m2, and applying laboratory pressure and temperature conditions. Plume development in terms of onset time, sinking rate and wavelength statistics are closely comparable between experiment and model. This suggests therefore that the numerical flow simulator was able to reproduce the critical process of transition from diffusion-dominated to convection-dominated processes in a realistic way. This further increases our confidence in the suitability of numerical models in making predictions of system evolution within CO2 storage schemes.

  14. A web-based simulation system for transport and retention of dissolved contaminants in soil

    Microsoft Academic Search

    Honghai Zeng; Vladimir J. Alarcon; William Kingery; H. Magdi Selim; Jianping Zhu

    2002-01-01

    The movement of contaminants through the soil matrix is primarily a liquid phase process in which the chemical partitions between sorbed and dissolved phases. These phenomena have been modeled extensively and several computer models were developed. The use of those computer programs requires installation of the software in the users machine. Usually, post-processing of the numerical output provided by the

  15. Photochemical degradation of chromophoric-dissolved organic matter exposed to simulated UV-B and natural solar radiation

    Microsoft Academic Search

    Yunlin Zhang; Mingliang Liu; Boqiang Qin; Sheng Feng

    2009-01-01

    Photochemical degradation of chromophoric-dissolved organic matter (CDOM) by UV-B radiation decreases CDOM absorption in the\\u000a UV region and fluorescence intensity, and alters CDOM composition. CDOM absorption, fluorescence, and the spectral slope indicating\\u000a the CDOM composition were studied using 0.22-?m-filtered samples of Meiliang Bay water from Lake Taihu that were exposed to\\u000a short-term (0–12 h) simulated UV-B radiation and long-term (0–12 days)

  16. LIBS: Application to toxic metal concentration measurements in a plasma torch off-gas emission system

    SciTech Connect

    Singh, J.P.; Yueh, F.Y.; Zhang, H.; Etheridge, J.; Kirkland, R.L. [Mississippi State Univ., Mississippi State, MS (United States). Diagnostic Instrumentation and Analysis Lab.

    1995-12-31

    Laser-Induced Breakdown Spectroscopy (LIBS) has been used to monitor the metal concentrations of the off-gas system of a 250 kW plasma treatment system during vitrification of a Savannah River surrogate waste. LIBS spectra of different elements in the off-gas emission have been recorded in various spectral regions to select the appropriate spectral lines for the concentration measurements. The LIBS concentration measurement were then performed at different test run conditions. The results of various measurements are presented. These measurements demonstrated LIBS`s capability for real-time toxic metal monitoring.

  17. Cyclonic combustor for low-heating value off-gas incineration

    Microsoft Academic Search

    H. A. Abbasi; M. J. Khinkis; R. T. Waibel; S. R. Meder

    1984-01-01

    The combustion characteristics of a low-Btu off-gas and the operating performance of a 3 x 10⁶ Btu\\/h pilot-scale cyclonic combustor were investigated to evaluate the incineration and heat recovery potential. The average composition of the off-gas was 8.5% Hâ, 1.5% CO, 22% COâ, 56% Nâ, 3.4% CHâ and higher hydrocarbons, 7.3% HâO, 0.5% NHâ, and 0.15% HâS with a higher

  18. 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.

  19. 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 adsorption chemicals, solid-liquid separation methods, and achievable decontamination factors. Results of the radionuclide removal testing indicate that the radionuclides, including Tc-99, can be removed with inorganic sorbents and precipitating agents. Evaporation test results indicate that the simulant can be evaporated to fairly high concentration prior to formation of appreciable solids, but corrosion has not yet been examined.

  20. 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.

  1. Off-gas cleanup system considerations for fluidized-bed radioactive waste calcination at the ICPP

    Microsoft Academic Search

    Freeby

    1978-01-01

    Air fluidization, off-gas recycle, and steam fluidization are evaluated as process alternatives for a waste calcining facility. Emphasis in the study was on the capability of each process to reduce radiochemical and chemical emissions to as low as practicable while minimizing system complexity and potential for calciner downtime.

  2. A FISSION GAS MONITOR FOR GAS COOLED OR OFF-GAS EXPERIMENTAL SYSTEMS

    Microsoft Academic Search

    J. F. Sommers; I. J. Wells

    1959-01-01

    The fission gas monitor is a very sensitive instrument for the detection ; of fresh fission products in gas cooled or off-gas systems. It is quite ; versatile so that it can be used on a wide variety of experiments either as a ; quick, positive, and sensitive detector of fission products or as a quantitative ; measuring device for

  3. Off-gas treatment and characterization for a radioactive in situ vitrification test

    SciTech Connect

    Oma, K.H.; Timmerman, C.L.

    1984-08-01

    Effluents released to the off gas during the in situ vitrification (ISV) of a test site have been characterized by Pacific Northwest Laboratory. The site consisted of a 19 L waste package of soil containing 600 nCi/g transuranic and 30,000 nCi/g mixed fission products surrounded by uncontaminated soil. Radioactive isotopes present in the package were /sup 241/Am, /sup 238///sup 239/Pu, /sup 137/Cs, /sup 106/Ru, /sup 90/Sr, and /sup 60/Co. The ISV process melted the waste package and surrounding soil and immobilized the radionuclides in place, producing a durable, 8.6 metric ton glass and crystalline monolith. The test successfully demonstrated that the process provides containment of radioactive material. No release to the environment was detected during processing of cooldown. Due to the high temperature during processing, some gases were released into the off-gas hood that was over the test site. The hood was maintained at a slight negative pressure to contain any volatile or entrained material during processing. Gases passed from the hood to an off-gas treatment system where they were treated using a venturi-ejector scrubber, a tandem nozzle gas cleaner scrubber followed by a condenser, heater, and two stages of HEPA filters. The off-gas treatment system is located in the semi-trailer to allow transport of the process to other potential test sites. Retention of all radionuclides by the vitrified zone was greater than 99%. Soil-to-off-gas decontamination factors (DFs) for transuranic elements averaged greater than 4000 and for fission products, DFs ranged from 130 for /sup 137/Cs to 3100 for /sup 90/Sr. 7 references, 15 figures, 4 tables.

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

    SciTech Connect

    Sokhansanj, Shahabaddine [ORNL; Kuang, Xingya [University of British Columbia, Vancouver; Shankar, T.S. [University of British Columbia, Vancouver; Lim, C. Jim [University of British Columbia, Vancouver; Bi, X.T. [University of British Columbia, Vancouver; Melin, Staffan [University of British Columbia, Vancouver

    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.

  5. 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.

  6. 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.

  7. Evaluation of oxygen transfer efficiency under process conditions using the dynamic off-gas method.

    PubMed

    Schuchardt, A; Libra, J A; Sahlmann, C; Wiesmann, U; Gnirss, R

    2007-05-01

    The off-gas method can be used to investigate standard oxygen transfer efficiencies under process conditions (alphaSOTE) over the operating life of an aeration system. A method to evaluate alphaSOTE is described in detail by US and German standards. The standards, however, do not describe how to evaluate dynamic changes in aSOTE over a day, which can be useful to uncover problems and unfavourable process conditions. Based on over three years experience gained in off-gas testing in Berlin wastewater treatment plants (WWTPs) under operating conditions, a method to evaluate and interpret the dynamic changes in oxygen transfer is presented. The application of the dynamic off-gas method brings important additional information, which can be used to increase operational efficiency of the aeration basin and to increase process reliability, with a relatively small increase in effort. This paper shows how to perform dynamic measurements under process conditions. Some results of such measurements under dynamic process conditions, performed in a Berlin WWTP, are discussed. PMID:17615957

  8. 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.

  9. 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.

  10. 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

  11. Off-gas characteristics of defense waste vitrification using liquid-fed Joule-heated ceramic melters

    Microsoft Academic Search

    R. W. Goles; G. J. Sevigny

    1983-01-01

    Off-gas and effluent characterization studies have been established as part of a PNL Liquid-Fed Ceramic Melter development program supporting the Savannah River Laboratory Defense Waste Processing Facility (SRL-DWPF). The objectives of these studies were to characterize the gaseous and airborne emission properties of liquid-fed joule-heated melters as a function of melter operational parameters and feed composition. All areas of off-gas

  12. 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

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

    NASA Astrophysics Data System (ADS)

    Antanasijevi?, Davor; Pocajt, Viktor; Peri?-Gruji?, Aleksandra; Risti?, 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.

  14. 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. [Univ. of Cincinnati, OH (United States). Dept. of Civil and Environmental Engineering; Siddiqui, K. [Hamilton County Metropolitan Sewer District, Cincinnati, OH (United States)

    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).

  15. 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

  16. ASSESSMENT OF THE IMPACT OF TOA PARTITIONING ON DWPF MELTER OFF-GAS FLAMMABILITY

    SciTech Connect

    Daniel, G.

    2013-06-18

    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.

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

    SciTech Connect

    Tipping, Ed [Lancaster Environment Center; Chamberlain, Paul M. [Lancaster Environment Center; Froberg, Mats J. [Sveriges Lantbruksuniversitet; Hanson, Paul J [ORNL; Jardine, Philip M [ORNL

    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 timescales of 1 to 15 years, but there is a conversion of 11 gC m-2 a-1 into stabilised forms that turnover on a timescale of 100-200 years. The small flux of DOC leaving the B-horizon (1.2 gC m-2 a-1) is mainly hydrophilic material, some of which can penetrate to depth quickly after formation. Considering the soil profile as single entity, the simulated soil carbon pools at ORR have mean residence times in the range 1-200 years, most of the carbon being in the slow pools, most of the turnover associated with the faster ones.

  18. 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)

  19. Fabrication of remote steam atomized scrubbers for DDWPF (Defense Waste Processing Facility) off-gas system

    SciTech Connect

    Nielsen, M.G.; Lafferty, J.D.

    1988-01-01

    The Defense Waste Processing Facility (DWPF) is being constructed for the purpose of processing high-level waste from liquid sludge to a vitrified borosilicate glass. In the operation of continuous slurry-fed melters, off-gas aerosols are created by entrainment of feed slurried and the vaporization of volatile species from the molten glass mixture. It is necessary to decontaminate these aerosols in order to minimize discharge of airborne radionuclide particulates. A Steam Atomized Scrubber (SAS) has been developed for DWPF which utilizes a patented Hydro-Sonic System gas scrubbing method. The Hydro-Sonic System utilizes a steam aspirating-type venturi scrubber that requires very precise fabrication tolerances in order to obtain acceptable decontamination factors. In addition to the process-related tolerances, precision mounting and nozzle tolerances are required for remote service at DWPF.

  20. Desulfurization of 10-ton retort off-gas using a Venturi scrubber

    SciTech Connect

    Place, B.G.; Barbour, F.A.; Owen, T.E.; Hobbs, R.; Turner, T.F.

    1985-05-01

    WRI has investigated Venturi scrubber performance in desulfurizing off-gas generated by WRI's 10-ton oil shale retort. A theory of weak electrolyte transport is derived, and two computer models are developed which describe desulfurization. Data on hydrogen sulfide removal and transmissometry are presented. The hydrogen sulfide removal data are analyzed using the above models. Desulfurization was selective, regardless of the solvent used. Removal efficiencies of 60 to 70% were routinely observed, even though solvent concentrations were low compared with industrial applications. This suggests the use of a low-cost desulfurization process using a Venturi absorber. Based on the above, it is concluded that a Venturi scrubber may be the best device for the treatment of in situ oil shale retort gas. The transmissometry data show good correlation with Venturi operating parameters, demonstrating the usefulness of transmissometry applications.

  1. 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)

  2. Comparison of a fuel-driven and steam-driven ejector in solid oxide fuel cell systems with anode off-gas recirculation: Part-load behavior

    NASA Astrophysics Data System (ADS)

    Engelbracht, Maximilian; Peters, Roland; Blum, Ludger; Stolten, Detlef

    2015-03-01

    This paper investigates the use of ejectors for recirculating anode off-gas in an SOFC system, focusing on the part-load capability of two different systems. In the first system, recirculation was enabled by a fuel-driven ejector. The part-load threshold of this system was determined by carbon formation and was 77.8% assuming a fuel utilization of 70% and suitable ejector geometry. The second system was based on a steam-driven ejector. The simulation results for this system showed an improved part-load capability of 37.8% as well as a slightly improved electrical efficiency. Here, the minimal part load was determined by the condensation temperature of the condenser used in the system.

  3. 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.

  4. Off-gas characteristics of defense waste vitrification using liquid-fed Joule-heated ceramic melters

    SciTech Connect

    Goles, R.W.; Sevigny, G.J.

    1983-09-01

    Off-gas and effluent characterization studies have been established as part of a PNL Liquid-Fed Ceramic Melter development program supporting the Savannah River Laboratory Defense Waste Processing Facility (SRL-DWPF). The objectives of these studies were to characterize the gaseous and airborne emission properties of liquid-fed joule-heated melters as a function of melter operational parameters and feed composition. All areas of off-gas interest and concern including effluent characterization, emission control, flow rate behavior and corrosion effects have been studied using alkaline and formic-acid based feed compositions. In addition, the behavioral patterns of gaseous emissions, the characteristics of melter-generated aerosols and the nature and magnitude of melter effluent losses have been established under a variety of feeding conditions with and without the use of auxiliary plenum heaters. The results of these studies have shown that particulate emissions are responsible for most radiologically important melter effluent losses. Melter-generated gases have been found to be potentially flammable as well as corrosive. Hydrogen and carbon monoxide present the greatest flammability hazard of the combustibles produced. Melter emissions of acidic volatile compounds of sulfur and the halogens have been responsible for extensive corrosion observed in melter plenums and in associated off-gas lines and processing equipment. The use of auxiliary plenum heating has had little effect upon melter off-gas characteristics other than reducing the concentrations of combustibles.

  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.

    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 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, there are many process benefits to be gained by removing the steam-stripping step from the CPC c

  6. 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

  7. 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.

  8. 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

    2015-03-01

    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 more »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 CO?, 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, CO? is highest for switchgrass and CH? 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

  9. 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.

  10. 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

    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 comes 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 offgas 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 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, there are many process benefits to be gained by removing the steam-stripping step from the CPC c

  11. 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.

  12. Modeling of off-gas emissions from wood pellets during marine transportation.

    PubMed

    Pa, Ann; Bi, Xiaotao T

    2010-10-01

    After a fatal accident during the discharge of wood pellets at Helsingborg, emissions from pellets during marine transportation became a concern for the safe handling and storage of wood pellets. In this paper, a two-compartment model has been developed for the first time to predict the concentrations of CO, CO?, CH?, and O? inside the cargo ship and the time and rate of forced ventilation required before the safe entry into the stairway adjacent to the storage hatch. The hatch and stairway are treated as two perfectly mixed tanks. The gas exchange rate between these two rooms and the gas exchange rate with the atmosphere are fitted to satisfy a measured tracer final concentration of 33 p.p.m.v. in the stairway and an average final hatch to stairway CO, CO?, and CH? concentration ratio of 1.62 based on measurement from five other hatch and stairway systems. The reaction kinetics obtained from a laboratory unit using a different batch of pellets, however, need to be scaled in order to bring the prediction to close agreement with onboard measured emission data at the end of voyage. Using the adjusted kinetic data, the model was able to predict the general trend of data recorded in the first 12.5 days of the voyage. Further validation, however, requires the data recorded over the whole journey. The model was applied to predict the effect of ocean temperature on the off-gas emissions and the buildup of concentrations in the hatch and stairway. For safe entry to the cargo ship, the current model predicted that a minimal ventilation rate of 4.4 hr?¹ is required for the stairway's CO concentration to lower to a safe concentration of 25 p.p.m.v. At 4.4 hr?¹, 10 min of ventilation time is required for the safe entry into the stairway studied. PMID:20603277

  13. 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

  14. 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.

  15. Thermoeconomic optimization of a cryogenic refrigeration cycle for re-liquefaction of the LNG boil-off gas

    Microsoft Academic Search

    Hoseyn Sayyaadi; M. Babaelahi

    2010-01-01

    The development of the liquefaction process for the Liquefied Natural Gas (LNG) boil-off re-liquefaction plants will be addressed to provide an environmentally friendly and cost effective solution for the gas transportation. In this manner, onboard boil-off gas (BOG) re-liquefaction system as a cryogenic refrigeration cycle is utilized in order to re-liquefy the BOG and returns it to the cargo tanks

  16. 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.

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

    SciTech Connect

    Nenoff, Tina Maria; Chupas, Peter J. (Argonne National Laboratory); Garino, Terry J.; Rodriguez, Mark Andrew; Chapman, Karena W. (Argonne National Laboratory); 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-ray single-crystal analyses, in conjunction with high pressure differential pair distribution function (d-PDF) studies aimed to identify preferential sites in the pores, and improve MOFs robustness. Furthermore, durability studies on the iodine loaded MOFs and subsequent waste forms include thermal analyses, SEM/EDS elemental mapping, and leach-durability testing. We anticipate for this in-depth analysis to further aid the design of advanced materials, capable to address major hallmarks: safe capture, stability and durability over extended timeframes.

  18. A global model of the marine ecosystem for long-term simulations: Sensitivity to ocean mixing, buoyancy forcing, particle sinking, and dissolved organic matter cycling

    NASA Astrophysics Data System (ADS)

    Schmittner, A.; Oschlies, A.; Giraud, X.; Eby, M.; Simmons, H. L.

    2005-09-01

    A new model of the marine ecosystem coupled into a global Earth System Climate Model suitable for long-term (multimillennial timescale) simulations is presented. The model is based on nitrate as the sole limiting nutrient. Prognostic equations for nutrients, phytoplankton, zooplankton, and detritus are solved online in the three-dimensional ocean circulation model component. Experiments with different parameterizations of vertical mixing, including a scheme of tidally driven mixing, changes in buoyancy forcing in the Southern Ocean, different particle sinking velocities, and the inclusion of dissolved organic matter are performed, and the results are compared with observations. The results reemphasize the roles of Southern Ocean freshwater forcing and diapycnal mixing in the low-latitude pycnocline in setting the global deep water circulation and properties. The influence of high mixing in the Southern Ocean as inferred from observations is much more limited. The deep water circulation also has a strong influence on the marine ecosystem and nutrient distributions. We demonstrate that larger values of vertical diffusion lead to a shallower nutricline due to increased upwelling. Export production and nutrient distributions respond sensitively to changes in mixing and to the ratio of particle sinking to remineralization in the upper ocean. The best fits to global measurements of temperature, salinity, deep ocean radiocarbon, mixed layer depth, nutrients, and chlorophyll are obtained for values of vertical mixing in the pycnocline of around 0.2-0.3 × 10-4 m2/s and for e-folding depth for particle remineralization of 100-200 m. A simple parameterization of dissolved organic matter dynamics increases primary production and nutrient concentrations in the upper ocean and improves chlorophyll distributions in the subtropical gyres but has no discernible influence on particulate export fluxes. Remaining model deficiencies are identified, and strategies for future model improvement are outlined.

  19. Studying dissolved organic carbon export from the Penobscot Watershed in to Gulf of Maine using Regional Hydro-Ecological Simulation System (RHESSys)

    NASA Astrophysics Data System (ADS)

    Rouhani, S. F. B. B.; Schaaf, C.; Douglas, E. M.; Choate, J. S.; Yang, Y.; Kim, J.

    2014-12-01

    The movement of Dissolved Organic Carbon (DOC) from terrestrial system into aquatic system plays an important role for carbon sequestration in ecosystems and affects the formation of soil organic matters.Carbon cycling, storage, and transport to marine systems have become critical issues in global-change science, especially with regard to northern latitudes (Freeman et al., 2001; Benner et al., 2004). DOC, as an important composition of the carbon cycling, leaches from the terrestrial watersheds is a large source of marine DOC. The Penobscot River basin in north-central Maine is the second largest watershed in New England, which drains in to Gulf of Maine. Approximately 89% of the watershed is forested (Griffith and Alerich, 1996).Studying temporal and spatial changes in DOC export can help us to understand terrestrial carbon cycling and to detect any shifts from carbon sink to carbon source or visa versa in northern latitude forested ecosystems.Despite for the importance of understanding carbon cycling in terrestrial and aquatic biogeochemistry, the Doc export, especially the combination of DOC production from bio-system and DOC transportation from the terrestrial in to stream has been lightly discussed in most conceptual or numerical models. The Regional Hydro-Ecological Simulation System (RHESSys), which has been successfully applied in many study sites, is a physical process based terrestrial model that has the ability to simulate both the source and transportation of DOC by combining both hydrological and ecological processes. The focus of this study is on simulating the DOC concentration and flux from the land to the water using RHESSys in the Penobscot watershed. The simulated results will be compared with field measurement of DOC from the watershed to explore the spatial and temporal DOC export pattern. This study will also enhance our knowledge to select sampling locations properly and also improve our understanding on DOC production and transportation in terrestrial forest ecosystem.

  20. 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.

  1. Distributions of 14 elements into 10 liquid extractants from simulated acid-dissolved sludge and acidified supernate solutions of Hanford high-level waste

    SciTech Connect

    Marsh, S.F. [Sandia National Labs., Albuquerque, NM (United States); Svitra, Z.V.; Bowen, S.M. [Los Alamos National Lab., NM (United States)

    1994-02-01

    The distributions of 14 elements into ten extractants were measured from simulant solutions that represent acidic dissolved sludge and acidified supernate from Hanford HLW Tank 102-SY. The extractants: LIX{sup TM}-26, LIX{sup TM}-54, LIX{sup TM}-84, LIX{sup TM}-1010, Cyanex{sup TM} 272, Cyanex{sup TM} 923, Aliquat{sup TM} 336, DHDECMP, DHDECMP-DIPB, and CMPO-DIPB, were sorbed on porous carbon beads to provide dry-appearing beads that would be suitable for column operations. 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 measured by gamma spectrometry. Distribution coefficients for each of 280 element/absorber/solution combinations were measured for dynamic contact periods of 30 minutes, 2 hours, and 6 hours to provide sorption kinetics information for the selected elements from these complex media. The resulting 840 measured distribution coefficients are presented.

  2. Results for the DWPF Slurry Mix Evaporator Condensate Tank, Off Gas Condensate Tank, And Recycle Collection Tank Samples

    SciTech Connect

    TERRI, FELLINGER

    2004-12-21

    The Defense Waste Processing Facility, DWPF, currently generates approximately 1.4 million gallons of recycle water per year during Sludge-Only operations. DWPF has minimized condensate generation to 1.4 million gallons by not operating the Steam Atomized Scrubbers, SASs, for the melter off gas system. By not operating the SASs, DWPF has reduced the total volume by approximately 800,000 gallons of condensate per year. Currently, the recycle stream is sent to back to the Tank Farm and processed through the 2H Evaporator system. To alleviate the load on the 2H Evaporator system, an acid evaporator design is being considered as an alternate processing and/or concentration method for the DWPF recycle stream. In order to support this alternate processing option, the DWPF has requested that the chemical and radionuclide compositions of the Off Gas Condensate Tank, OGCT, Slurry Mix Evaporator Condensate Tank, SMECT, Recycle Collection Tank, RCT, and the Decontamination Waste Treatment Tank, DWTT, be determined as a part of the process development work for the acid evaporator design. Samples have been retrieved from the OGCT, RCT, and SMECT and have been sent to the Savannah River National Laboratory, SRNL for this characterization. The DWTT samples have been recently shipped to SRNL. The results for the DWTT samples will be issued at later date.

  3. Development of submicron particle size classification and collection techniques for nuclear facility off-gas streams. [Diffusion battery and electrofluidized bed

    SciTech Connect

    Hohorst, F.A.; Fernandez, S.J.

    1981-02-01

    High efficiency particulate air (HEPA) filters are an essential part of nuclear facility off-gas cleanup systems. However, HEPA-rated sampling filters are not the most appropriate samplers for the particle penetrating off-gas cleanup systems. Previous work at the Idaho Chemical Processing Plant (ICPP) estimated perhaps 5% of the radioactivity that challenged sampling filters penetrated them in the form of submicron particles - typically less than 0.2 microns. Accordingly, to evaluate these penetrating aerosols more fully, a suitable robust monitoring system for size differentiation and measurement of submicron particles was developed. A literature survey revealed that the diffusion battery was the best choice for particle size classification and that the electrofluidized bed was the best method for particle collection in ICPP off-gas streams. This report describes the laboratory study and in-plant demonstration of these two techniques.

  4. 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.

  5. Photobleaching of humic rich dissolved organic matter

    Microsoft Academic Search

    Thomas Brinkmann; Daniel Sartorius; Fritz H. Frimmel

    2003-01-01

    Humic rich dissolved organic matter (DOM) from a bog lake in the Northern Black Forest was treated with simulated solar UV-light. The effects of irradiation time, initial pH values, and dissolved iron and copper on photobleaching were investigated. The DOC concentration and the UV\\/VIS absorption decreased with increasing amounts of absorbed light energy. The wavelengths of the maximum bleaching effect

  6. 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.

  7. 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{sub v}, at a given time, t. The units for G{sub v} and t are ft{sup 3}/ft{sup 2}/min and hours, respectively. The total volume of hydrogen gas generated during the test was calculated from the model equation. An upper bound on the total gas generated was determined from the upper 95% confidence limit. The upper bound limit on the total hydrogen generated during the 163 hour test was 0.332 ft{sup 3}/ft{sup 2}. The maximum instantaneous hydrogen generation rate for this scenario is greater than that previously measured in the 8 wt.% oxalic acid tests due to both the absence of sludge in the test (i.e., greater than 20:1 ratio of acid to sludge) and the use of polished coupons (vs. mill scale coupons). However, due to passivation of the carbon steel surface, the corrosion rate decays by an order of magnitude within the first three days of exposure such that the instantaneous hydrogen generation rates are less than that previously measure in the 8 wt.% oxalic acid tests. While the results of these tests are bounding, the conditions used in this study may not be representative of the ECC flowsheet, and the applicability of these results to the flowsheet should be evaluated for the following reasons: (1) The absence of sludge results in higher instantaneous hydrogen generation rates than when the sludge is present; and (2) Polished coupons do not represent the condition of the carbon steel interior of the tank, which are covered with mill scale. Based on lower instantaneous corrosion rates measured on mill scale coupons exposed to oxalic acid, lower instantaneous hydrogen generation rates are expected for the tank interior than measured on the polished coupons. Corrosion rates were determined from the coupon tests and also calculated from the measured hydrogen generation rates. Excellent agreement was achieved between the time averaged corrosion rate calculated from the hydrogen generation rates and the corrosion rates determined from the coupon tests. The corrosion rates were on the order of 18 to 28 mpy. Good agreement was also observed between the maximum instantaneo

  8. Pill Dissolving Demo

    NSDL National Science Digital Library

    2014-09-18

    In a class demonstration, the teacher places different pill types ("chalk" pill, gel pill, and gel tablet) into separate glass beakers of vinegar, representing human stomach acid. After 20-30 minutes, the pills dissolve. Students observe which dissolve the fastest, and discuss the remnants of the various pills. What they learn contributes to their ongoing objective to answer the challenge question presented in lesson 1 of this unit.

  9. 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.

  10. Labview Based Dissolved Oxygen Sensor

    Microsoft Academic Search

    Fenghong Chu; Junjie Yang

    2009-01-01

    A dissolved oxygen sensor based on data acquisition card and Labview was studied in this paper. The stimulated light and fluorescence light signal was fed to the data acquisition card of the computer, and by Labview software we calculated the fluorescence lifetime, based on the relationship between fluorescence lifetime and dissolved oxygen concentration we got the dissolved oxygen concentration.

  11. Real-time monitoring of shake flask fermentation and off gas using triple disposable noninvasive optical sensors.

    PubMed

    Ge, Xudong; Rao, Govind

    2012-01-01

    Bioprocess development is a data-driven process requiring a large number of experiments to be conducted under varying conditions. Small-scale upstream bioprocess development is often performed in shake flasks because they are inexpensive and can be operated in parallel. However, shake flasks are often not equipped to accurately monitor critical process parameters such as pH, dissolved oxygen, and CO2 concentrations. Therefore, there is no definitive information on oxygen supply of growing cells, CO2 formation, and pH changes. Here we describe several shake flask fermentations where all three parameters are monitored by disposable noninvasive optical sensors. The sensitive element of these sensors is a thin, luminescent patch affixed inside the flask. Small electronic devices for excitation and fluorescence detection are positioned outside the shake flask for noninvasive monitoring. By measuring the process parameters throughout the course of the E. coli fermentations, we obtain information that is not routinely available in shake flask fermentations. For example, for cultures with only a few millimeters liquid depth, oxygen limitation can occur at relatively low agitation speeds. Under certain conditions oscillations in dissolved oxygen can occur. An increase in shaker speed and a decrease in culture volume can increase the oxygen availability and reduce the duration of oxygen limitation. PMID:22323391

  12. 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

  13. Utilization of LOTUS computer program for rotary kiln, secondary combustion chamber and off-gas system design for a mixed and LLW incinerator

    SciTech Connect

    Sanders, N.; Voshell, M.E.

    1987-04-01

    This paper discusses the advantages of the LOTUS 1-2-3 spreadsheet as used in the design of an incineration facility. The program is used to calculate material and energy balances, excess air requirements, and temperature control requirements. The flexibility of the LOTUS system in exploring a variety of design scenarios is discussed. The spreadsheet models a rotary kiln which burns solids and liquids and a secondary combustion chamber which burns liquids. The incineration facility uses a wet scrubbing off-gas system for particulates and acid gas removal and control. The computer program is extremely useful for calculating excess air and fuel oil requirements for incineration system temperature control and for determining off-gas system flow rates. The single most important factor is that once all the chemical equations for all wastes to be fired have been developed and the spreadsheet set up, any number of cases may be evaluated. This is essential to compare the effects of feed components on flue gas volume, quantities of acid gases and metal oxides generated, and particulate loading, all of which affect the proper sizing, selection and cost of equipment.

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

    Microsoft Academic Search

    KRUGER AA; MATLACK KS; BARDAKCI T; DANGELO NA; GONG W; KOT WK; PEGG IL

    2011-01-01

    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

  15. 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

  16. 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.

  17. How to Measure Dissolved Oxygen

    NSDL National Science Digital Library

    Washington State University Department of Ecology

    This web page, hosted by the Washington State Department of Ecology, offers a general overview of dissolved oxygen and how it is measured. It includes protocols for measuring dissolved oxygen in turbulent waters as well as using the Winkler titration method. The site also features links to measuring other water quality parameters such as pH, nutrients, and turbidity.

  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 petroleum coke calcination process. - Increase the opportunity of heat (chemical and physical) utilization from process off-gases and solid product. - Develop a design of advanced CHP system utilizing off-gases as an “opportunity fuel” for petroleum coke calcinations and sensible heat of calcined coke. A successful accomplishment of the aforementioned objectives will contribute toward the following U.S. DOE programmatic goals: - Drive a 25% reduction in U. S. industrial energy intensity by 2017 in support of EPAct 2005; - Contribute to an 18% reduction in U.S. carbon intensity by 2012 as established by the Administration’s “National Goal to Reduce Emissions Intensity.” 8

  19. 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-CH?/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

  20. Interactions Among Dissolved Nitrogen, Phosphate, and Dissolved Oxygen at Several Sites in Chesapeake Bay in 2000

    NSDL National Science Digital Library

    Charlie Hunter (Southwestern College; )

    2006-06-18

    We looked at the correlation between dissolved oxygen and two water quality variables: dissolved nitrogen and dissolved phosphorus. We thought that, if dissolved oxygen were highly correlated with dissolved nitrogen (for example), then that would imply that dissolved nitrogen was limiting or otherwise important at that site. Likewise for dissolved phosphorus. We found that different sites in the bay had different levels of correlation, but there was no spatial pattern to the data.

  1. 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.

  2. 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.

  3. 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.

  4. 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 statistically significant (Mann-Whitney U) difference in THM formation (p<0.05) as well as the amount of DOM produced and specific UV absorption at 254nm (p<0.01) between vegetation classes.

  5. ICPP custom dissolver explosion recovery

    SciTech Connect

    Demmer, R.; Hawk, R.

    1992-06-11

    This report discusses the recovery from the February 9, 1991 small scale explosion in a custom processing dissolver at the Idaho Chemical Processing Plant. Custom processing is a small scale dissolution facility which processes nuclear material in an economical fashion. The material dissolved in this facility was uranium metal, uranium oxides, and uranium/fissium alloy in nitric acid. The paper explained the release of fission material, and the decontamination and recovery of the fuel material. The safety and protection procedures were also discussed. Also described was the chemical analysis which was used to speculate the most probable cause of the explosion. (MB)

  6. Continuous monitoring of dissolved oxygen

    Microsoft Academic Search

    Barron

    1965-01-01

    Modification of portable oxygen meters allows continuous monitoring of dissolved oxygen in waterflood systems, instead of using spot checks which permit only partial oxygen removal. This is made possible by the addition of an automatic, continuous readout instrument to the common oxygen sensor in use today. The oxygen sensor consists of an electrolytic cell made of a cathode, an anode,

  7. Phase fluorometric dissolved oxygen sensor

    Microsoft Academic Search

    C. McDonagh; C. Kolle; A. K. McEvoy; D. L. Dowling; A. A. Cafolla; S. J. Cullen; B. D. MacCraith

    2001-01-01

    The design and performance of a ruggedised dissolved oxygen (DO) probe, which is based on phase fluorometric detection of the quenched fluorescence of an oxygen-sensitive ruthenium complex, is reported. The complex is entrapped in a porous hydrophobic sol–gel matrix that has been optimised for this application. The LED excitation and photodiode detection are employed in a dipstick probe configuration, with

  8. 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 ?-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% ?-cellulose and 89% brightness after D0EpD1EpD1 bleaching. The produced dissolving pulp can be used in rayon production. PMID:25439866

  9. 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.

  10. 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.

  11. Mechanisms controlling dissolved iron distribution in the North Pacific: A model study

    E-print Network

    2011-01-01

    in deter- mining surface water distributions of Al and Fe inthe distribution of Fe and Al in the surface waters of theDistribution [ 20 ] The simulated dissolved iron concentrations in the surface water

  12. The interaction of iodine with insoluble residue in the dissolution of simulated spent-fuel pellets

    SciTech Connect

    Sakurai, T.; Takahashi, A.; Ishikawa, N.; Komaki, Y. (Japan Atomic Energy Research Inst., Physical Chemistry Lab., Tokai-mura, Ibaraki-ken 319-11 (JP))

    1991-04-01

    To properly control radioiodine ({sup 129}I) when reprocessing nuclear fuels, it is important to understand the interaction between iodine and the insoluble residue produced during the dissolution of spent fuels. Simulated spent-fuel pellets ({approximately} 1 g each) equivalent to spent fuel with a burnup of 5% fima were dissolved in 4.1 M HNO{sub 3} or a simulated spent-fuel solution to examine this interaction and the material balance of iodine. In dissolution in 4.1 M HNO{sub 3}, 2 to 5% of the iodine in the pellet is conveyed to the insoluble residue (8 {plus minus} 1 mg), 1 to 5% remains in solution, and the balance volatilizes into the off-gas. The process that incorporates iodine into the residue is the formation of slightly soluble iodides, such as PdI{sub 2} and AgI, on the surface of the residue. The quantity of iodine in the residue averages 1.1 {plus minus} 0.5 Mg I/mg of residue. Pellet dissolution in simulated spent-fuel solutions with a uranium concentration of {ge}170 g U/{ell} and corresponding amounts of fission product elements causes a marked increase in the amount of residue and a significant increase in the amount of iodine involved. This phenomenon is due to the secondary precipitation of some metal molybdates. The PdI{sub 2} and AgI in the residue are in equilibrium with Pd{sup 2+}, Ag{sup +}, and I{sup {minus}} in the solution. The I{sup {minus}} can be oxidized into I{sub 2} in a hot nitric acid solution bubbled with NO{sub 2}. The action of NO{sub 2} causes part of the iodine in the residue to be eluted into the solution and then volatilized into the off-gas during the operation to expel iodine (IO{sup {minus}}{sup 3}) form the solution. A process consisting of (a) heating of the residue in a IO{sup {minus}}{sub 3}-concentrated HNO{sub 3} at 100{degrees} C will transfer 50 to 90% of the iodine in the residue to the gas phase. The remaining iodine is probably inside the residue as it is difficult to remove.

  13. Simulations of Dissolved and Particulate Organic Matter with a Nitrogen-based Oceanic Ecosystem Model: A one Dimensional Model Applied to the Hawaii Ocean Time-series Station ALOHA

    Microsoft Academic Search

    S. L. Smith; Y. Yamanaka; M. J. Kishi

    2001-01-01

    Efforts are beginning to include oceanic ecosystem models in global simulations of the carbon cycle, to improve the representations of primary production and of the resulting oceanic uptake of carbon dioxide. Coupling complicated ecosystem models with three dimensional physical models to obtain meaningful simulations poses several challenges. Before proceeding to a three dimensional implementation, we have undertaken this study using

  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. 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…

  16. Dissolved Gaseous Mercury Concentrations and Mercury

    E-print Network

    O'Driscoll, Nelson

    % of total annual mercury inputs to the system, and studies on the Great Lakes (Canada-United States) showDissolved Gaseous Mercury Concentrations and Mercury Volatilization in a Frozen Freshwater Fluvial to examine dissolved gaseous mercury (DGM), mercury volatilization, and sediment interactions in a frozen

  17. 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...

  18. Temporal evolution of hyporheic dissolved organic carbon

    NASA Astrophysics Data System (ADS)

    Gabrielsen, P. J.

    2010-12-01

    Dissolved organic carbon (DOC) is a complex suite of organic compounds present in natural ecosystems, and is particularly studied in river 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 riverine 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. This presentation examines the effect of organic and inorganic HZ DOC processes, i.e. microbial uptake and sorption, respectively, on DOC quality as measured through molecular weight distributions (MWDs). Sediment and water samples from East Fork Jemez River in northern New Mexico are used to experimentally simulate DOC processes and observe the subsequent effect on MWD evolution. Parallel factor analysis (PARAFAC) of excitation-emission matrices (EEMs) is also used to examine fluorescent properties throughout DOC process experimentation, providing a second characterizing metric. Results from this study will be applied to a field sampling campaign in the summer of 2011 along the East Fork Jemez River to study temporal and spatial variability in organic and inorganic DOC processes.

  19. Dissolved air flotation and me.

    PubMed

    Edzwald, James K

    2010-04-01

    This paper is mainly a critical review of the literature and an assessment of what we know about dissolved air flotation (DAF). A few remarks are made at the outset about the author's personal journey in DAF research, his start and its progression. DAF has been used for several decades in drinking water treatment as an alternative clarification method to sedimentation. DAF is particularly effective in treating reservoir water supplies; those supplies containing algae, natural color or natural organic matter; and those with low mineral turbidity. It is more efficient than sedimentation in removing turbidity and particles for these type supplies. Furthermore, it is more efficient in removing Giardia cysts and Cryptosporidium oocysts. In the last 20 years, fundamental models were developed that provide a basis for understanding the process, optimizing it, and integrating it into water treatment plants. The theories were tested through laboratory and pilot-plant studies. Consequently, there have been trends in which DAF pretreatment has been optimized resulting in better coagulation and a decrease in the size of flocculation tanks. In addition, the hydraulic loading rates have increased reducing the size of DAF processes. While DAF has been used mainly in conventional type water plants, there is now interest in the technology as a pretreatment step in ultrafiltration membrane plants and in desalination reverse osmosis plants. PMID:20096437

  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. Impact of circulation on export production, dissolved organic matter, and dissolved oxygen in the ocean: Results from Phase II of the Ocean

    E-print Network

    Follows, Mick

    in the ocean: Results from Phase II of the Ocean Carbon-cycle Model Intercomparison Project (OCMIP-2) R. G) and dissolved oxygen simulated by 12 global ocean models participating in the second phase of the Ocean Carbon-resolution ocean circulation models. The model mean (±1s) downward flux of organic matter across 75 m depth is 17

  2. Dissolved aluminum in the Gulf of Mexico 

    E-print Network

    Myre, Peggy Lynne

    1990-01-01

    concentration 37 11) Di. ssolved aluminum profiles from the Northwest Atlantic Ocean, Caribbean Sea and the Gulf of Mexico 12) Dissolved aluminum from the Atlantic Ocean and the Pacific Ocean INTRODUCTION The processes which control the concentration... s input Dissolved al uminum wa s measured at seven stations in the Northwest Gulf of Mexico in water depths ranging from 0 t o 1 1 8 3 meters above the continental slope . Samples were chosen in waters above the continental slope t o distinguish...

  3. 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. (BATTELLE (PACIFIC NW LAB)); Amidan, Brett G. (BATTELLE (PACIFIC NW LAB)); Cada, G F. (ORNL)

    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 surface pressure for a 48-hour post exposure observation period. No fall chinook salmon died during or after exposure to the horizontal bulb turbine passage pressures, and no injuries were observed during the 48-hour post exposure observation period. As with the previous test series, it cannot be determined whether fall chinook salmon acclimated to the greater water pressure during the pretest holding period. For bluegill sunfish exposed to the horizontal bulb turbine turbine-passage pressures, only one fish died and injuries were less severe and less common than for bluegills subjected to either the"worst case" pressure or modified Kaplan turbine pressure conditions in previous tests. Injury rates for bluegills were higher at 0.7 atm nadir than for the 0.95 atm nadir. However, injuries were limited to minor internal hemorrhaging. Bluegills did not suffer swim bladder rupture in any tested scenarios. 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.

  4. Reduced dissolved oxygen and jet fuel deposition

    SciTech Connect

    Ervin, J.S.; Heneghan, S.P.; Williams, T.F.; Hanchak, M.A. [Univ. of Dayton, OH (United States)

    1995-12-31

    A fundamental understanding of the effect of low dissolved oxygen concentrations on thermal stability (thermal stability refers to the deposit forming tendency of the fuel) is incomplete but is essential for aircraft fuel system design. At high altitudes, the ambient pressure and temperature are reduced significantly, resulting in the diminished solubility of dissolved oxygen. In addition as a fire preventative measure, an on-board inert gas generating system (OBIGGS) may be used to reduce the oxygen level in the liquid fuel. Since these features lessen the dissolved oxygen concentration of the fuel, it is imperative to understand the effect of reduced oxygen levels on the formation of jet fuel deposits. For this purpose, the authors have conducted experiments using a flowing system in which the dissolved oxygen level at the entrance of the apparatus is varied. One of the most intriguing results found is the increase in deposits in heated sections for decreased oxygen consumption. This observation is seemingly contrary to nearly all previous observations concerning the relation between deposit formation and oxygen consumption. For a given system, there appears to be an unfavorable dissolved oxygen concentration which produces the maximum amount of deposits. In addition, it was found that the deposition mechanisms in heated locations were quite different from those in cooled regions.

  5. 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

  6. Dissolved Oxygen Levels in Lake Chabot

    NASA Astrophysics Data System (ADS)

    Sharma, D.; Pica, R.

    2014-12-01

    Dissolved oxygen levels are crucial in every aquatic ecosystem; it allows for the fish to breathe and it is the best indicator of water quality. Lake Chabot is the main backup water source for Castro Valley, making it crucial that the lake stays in good health. Last year, research determined that the water in Lake Chabot was of good quality and not eutrophic. This year, an experiment was conducted using Lake Chabot's dissolved oxygen levels to ensure the quality of the water and to support the findings of the previous team. After testing three specifically chosen sites at the lake using a dissolved oxygen meter, results showed that the oxygen levels in the lake were within the healthy range. It was then determined that Lake Chabot is a suitable backup water source and it continues to remain a healthy habitat.

  7. Process for coal liquefaction in staged dissolvers

    DOEpatents

    Roberts, George W. (Emmaus, PA); Givens, Edwin N. (Bethlehem, PA); Skinner, Ronald W. (Allentown, PA)

    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. Dissolved aluminum in the Gulf of Mexico

    E-print Network

    Myre, Peggy Lynne

    1990-01-01

    DISSOLVED ALUMINUM IN THE GULF OF MEXICO A Thesis by PEGGY LYNNE MYRE Submitted to the Office of Graduate Studies of Texas A6M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE August 1990 Majo...~ Subject: Oceanography DISSOLVED ALUMINUM IN THE GULF OF MEXICO A Thesis by PEGGY LYNNE MYRE Approved as to style and content by: David R. Schink (Chair of Committee) Jack G. Ba dauf (Member) Wilford D. Gardner (Member) John W. M rse (Member...

  9. 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.

  10. Influence of Dissolved Organic Materials on Turbid Water Optical Properties and Remote-Sensing Reflectance

    Microsoft Academic Search

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

    1982-01-01

    Results from both field measurements and laboratory simulations are used to assess the effects of dis- solved organic materials on turbid-water optical properties. Upwelled reflectance, attenuation, absorp- tion, and bckscatter spectral properties at wavelengths from 450 to 800 nm are examined in relation to water chemistry. From these data it is clear that dissolved organic materials decrease upwelled reflect- ance

  11. Pore-scale heterogeneous reaction rates on a dissolving limestone surface Yael Levensona

    E-print Network

    Simon, Emmanuel

    Pore-scale heterogeneous reaction rates on a dissolving limestone surface Yael Levensona , Simon simulations to show that this difference cannot be explained using a simple diffusion - surface reaction model that the rate of calcite dissolution within micron-size pores at the surface of a limestone sample is much lower

  12. TRANSPORT OF DISSOLVED ORGANICS FROM DILUTE AQUEOUS SOLUTIONS THROUGH FLEXIBLE MEMBRANE LINERS

    EPA Science Inventory

    This paper presents the results of experiments relating to the partitioning of dissolved organics from dilute aqueous solutions to polymeric flexihle memhrane liner (FMLs) and their permeation through these liners. n order to simulate partitioning and the transport of waste const...

  13. Oceanography June 200450 Colored Dissolved Organic

    E-print Network

    Oregon, University of

    blue sea" can typically be seen only hundreds of miles offshore. The areas of the ocean that most, red, blue, or green. The color of the ocean, when measured in full spectral detail, tells scientistsOceanography June 200450 Colored Dissolved Organic in the Coastal Ocean A N O P T I C A L TO O L F

  14. EFFECT OF DISSOLVED ORGANIC SUBSTANCES ON OYSTERS

    E-print Network

    and detailed studies of the effects of industrial wastes on oysters, Grassostrea virginica (Gmelin), continuousEF·FECT OF DISSOLVED ORGANIC SUBSTANCES· ON OYSTERS BY ALBERT COLLIER, S. M. RAY, A. W. MAGNITZKY gapes ~f !ileveral oysters recorded simultaneously indicated a parallel reaction to the concentration

  15. Developing Standards for Dissolved Iron in Seawater

    Microsoft Academic Search

    Kenneth S. Johnson; Edward Boyle; Kenneth Bruland; Kenneth Coale; Chris Measures; James Moffett; Ana Aguilar-Islas; Katherine Barbeau; Bridget Bergquist; Andrew Bowie; Kristen Buck; Yihua Cai; Zanna Chase; Jay Cullen; Takashi Doi; Virginia Elrod; Steve Fitzwater; Michael Gordon; Andrew King; Patrick Laan; Luis Laglera-Baquer; William Landing; Maeve Lohan; Jeffrey Mendez; Angela Milne; Hajime Obata; Lia Ossiander; Joshua Plant; Geraldine Sarthou; Peter Sedwick; Geoffrey J. Smith; Bettina Sohst; Sara Tanner; Stan Van den Berg; Jingfeng Wu

    2007-01-01

    In nearly a dozen open-ocean fertilization experiments conducted by more than 100 researchers from nearly 20 countries, adding iron at the sea surface has led to distinct increases in photosynthesis rates and biomass. These experiments confirmed the hypothesis proposed by the late John Martin that dissolved iron concentration is a key variable that controls phytoplankton processes in ocean surface waters.

  16. Reduced water density at hydrophobic surfaces: Effect of dissolved gases

    PubMed Central

    Doshi, Dhaval A.; Watkins, Erik B.; Israelachvili, Jacob N.; Majewski, Jaroslaw

    2005-01-01

    Here, direct noninvasive neutron reflectivity measurements reveal the presence of a reduced (deuterated) water density region, with a sigmoidal density profile at the hydrophobic silane–water interface that depends on the type and concentration of dissolved gases in the water. Removal of dissolved gases decreases the width of the reduced water density region, and their reintroduction leads to its increase. When compared with recent computer simulations, a locally fluctuating density profile is proposed, whereas preexisting nanobubbles are excluded. The presence of a fluctuating reduced water density region between two hydrophobic surfaces and the attractive “depletion force” to which it leads may help explain the hydrophobic force and its reported diminution in deaerated water. Our results are also quantitatively consistent with recent dynamic surface force apparatus results that drastically revise previous estimates of the slip length of water flowing past hydrophobic surfaces from microns to ?20 nm. Our observations, therefore, go a long way toward reconciling three quite different types of experiments and phenomena: water depletion at hydrophobic surfaces, water slip at hydrophobic surfaces, and the hydrophobic interaction. PMID:15976022

  17. Evaluation and Testing of IONSIV IE-911 for the Removal of Cesium-137 from INEEL Tank Waste and Dissolved Calcines

    SciTech Connect

    N. R. Mann; T. A. Todd; K. N. Brewer; D. J. Wood; T. J. Tranter; P. A. Tullock

    1999-04-01

    Development of waste treatment processes for the remediation of radioactive wastes is currently underway. A number of experiments were performed at the Idaho Nuclear Technology and Environmental Center (INTEC) located at the Idaho National Engineering and Environmental Laboratory (INEEL) with the commercially available sorbent material, IONSIV IE-911, crystalline silicotitanate (CST), manufactured by UOP LLC. The purpose of this work was to evaluate the removal efficiency, sorbent capacity and selectivity of CST for removing Cs-137 from actual and simulated acidic tank waste in addition to dissolved pilot-plant calcine solutions. The scope of this work included batch contact tests performed with non-radioactive dissolved Al and Run-64 pilot plant calcines in addition to simulants representing the average composition of tank waste. Small-scale column tests were performed with actual INEEL tank WM-183 waste, tank waste simulant, dissolved Al and Run-64 pilot plant calcine solutions. Small-scale column experiments using actual WM-183 tank waste resulted in fifty-percent Cs-137 breakthrough at approximately 589 bed volumes. Small-scale column experiments using the tank waste simulant displayed fifty-percent Cs-137 breakthrough at approximately 700 bed volumes. Small-scale column experiments using dissolved Al calcine simulant displayed fifty-percent Cs-137 breakthrough at approximately 795 bed volumes. Column experiments with dissolved Run-64, pilot plant calcine did not reach fifty-percent breakthrough throughout the test.

  18. 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...

  19. Microfabricated solid-state dissolved oxygen sensor

    Microsoft Academic Search

    Glen W. McLaughlin; Katie Braden; Benjamin Franc; Gregory T. A. Kovacs

    2002-01-01

    This paper describes the design, fabrication and testing of a microfabricated oxygen concentration sensor consisting of a microfabricated thin-film electrode matrix overlaid with a solid-state proton conductive matrix (PCM) and encapsulated in a bio-inert polytetrafluoroethelene (PTFE) film. Through cyclic voltammetry (CV) and voltage step (VS) measurements, the device was shown to have a linear response with respect to dissolved oxygen

  20. 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.

  1. Supersaturated dissolved oxygen measured by the phosphorescence decay rate

    Microsoft Academic Search

    Yongxia Zhang; Duane Johnson

    2003-01-01

    Unsaturated dissolved oxygen (DO) can be measured easily using oxygen probes based on electrochemistry. However, large concentrations of supersaturated dissolved oxygen are difficult to measure by traditional methods. We will introduce a new technique to measure supersaturated dissolved oxygen concentrations using the phosphorescence decay rate of a caged lumophore. The results are in good agreement with the Stern–Volmer equation, where

  2. Dissolved gaseous mercury behavior in shallow water estuaries 

    E-print Network

    Landin, Charles Melchor

    2008-10-10

    ................................ 51 xi FIGURE Page 17 Depth profiles of DGM, salinity, temperature, and dissolved oxygen for the July 2005 and November 2005 studies ....................................................... 54 18 Depth profiles of DGM, salinity..., temperature, and dissolved oxygen for the January 2006 and February 2006 studies.......................................................... 55 19 Depth profiles of DGM, salinity, temperature, and dissolved oxygen for the April 2006 and June 2006...

  3. Dissolved gaseous mercury behavior in shallow water estuaries 

    E-print Network

    Landin, Charles Melchor

    2009-05-15

    ................................ 51 xi FIGURE Page 17 Depth profiles of DGM, salinity, temperature, and dissolved oxygen for the July 2005 and November 2005 studies ....................................................... 54 18 Depth profiles of DGM, salinity..., temperature, and dissolved oxygen for the January 2006 and February 2006 studies.......................................................... 55 19 Depth profiles of DGM, salinity, temperature, and dissolved oxygen for the April 2006 and June 2006...

  4. HB-Line Dissolver Dilution Flows and Dissolution Capability with Dissolver Charge Chute Cover Off

    SciTech Connect

    Hallman, D.F.

    2003-01-15

    A flow test was performed in Scrap Recovery of HB-Line to document the flow available for hydrogen dilution in the dissolvers when the charge chute covers are removed. Air flow through the dissolver charge chutes, with the covers off, was measured. A conservative estimate of experimental uncertainty was subtracted from the results. After subtraction, the test showed that there is 20 cubic feet per minute (cfm) air flow through the dissolvers during dissolution with a glovebox exhaust fan operating, even with the scrubber not operating. This test also showed there is 6.6 cfm air flow through the dissolvers, after subtraction of experimental uncertainty if the scrubber and the glovebox exhaust fans are not operating. Three H-Canyon exhaust fans provide sufficient motive force to give this 6.6 cfm flow. Material charged to the dissolver will be limited to chemical hydrogen generation rates that will be greater than or equal to 25 percent of the Lower Flammability Limit (LFL) during normal operations. The H-Canyon fans will maintain hydrogen below LFL if electrical power is lost. No modifications are needed in HB-Line Scrap Recovery to ensure hydrogen is maintained less that LFL if the scrubber and glovebox exhaust fans are not operating.

  5. 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

  6. 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 mercury speciation and activity of methylating microorganisms. PMID:25007388

  7. Dissolved organic matter in the Baltic Sea

    NASA Astrophysics Data System (ADS)

    Hoikkala, L.; Kortelainen, P.; Soinne, H.; Kuosa, H.

    2015-02-01

    Several factors highlight the importance of dissolved organic matter (DOM) in coastal ecosystems such as the Baltic Sea: 1) DOM is the main energy source for heterotrophic bacteria in surface waters, thus contributing to the productivity and trophic state of bodies of water. 2) DOM functions as a nutrient source: in the Baltic Sea, more than one-fourth of the bioavailable nutrients can occur in the dissolved organic form in riverine inputs and in surface water during summer. Thus, DOM also supports primary production, both directly (osmotrophy) and indirectly (via remineralization). 3) Flocculation and subsequent deposition of terrestrial DOM within river estuaries may contribute to production and oxygen consumption in coastal sediments. 4) Chromophoric DOM, which is one of the major absorbers of light entering the Baltic Sea, contributes highly to water color, thus affecting the photosynthetic depth as well as recreational value of the Baltic Sea. Despite its large-scale importance to the Baltic Sea ecosystem, DOM has been of minor interest compared with inorganic nutrient loadings. Information on the concentrations and dynamics of DOM in the Baltic Sea has accumulated since the late 1990s, but it is still sporadic. This review provides a coherent view of the current understanding of DOM dynamics in the Baltic Sea.

  8. 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.

  9. Version 3.0 SOP 7 --Dissolved organic carbon October 12, 2007 Determination of dissolved organic

    E-print Network

    .1% by volume of the concentrated acid is added to each sample prior to analysis to lower the pH of the sample to pH pH and with sparging, all inorganic carbon species are converted to CO2 and removed should be evaluated for suitability. 2. Definition The dissolved organic carbon content of sea water

  10. Ocean metabolism and dissolved organic matter: How do small dissolved molecules persist in the ocean?

    Microsoft Academic Search

    Ronald Benner

    2010-01-01

    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

  11. Limitation of lowland riverine bacterioplankton by dissolved organic carbon and inorganic nutrients

    Microsoft Academic Search

    Douglas P. WesthorpeSimon; Simon M. Mitrovic; David Ryan; Tsuyoshi Kobayashi

    2010-01-01

    Flow regulation in lowland rivers has reduced the amount of allochthonous dissolved organic carbon (DOC) entering main channels\\u000a through less frequent wetting of benches, flood runners and floodplains. The hypothesis tested was that lowland riverine bacterioplankton\\u000a are DOC limited when flow events are absent and simulating an increase in assimilable DOC similar to that expected during\\u000a an environmental flow will

  12. Neural network approach to separate the non-algal absorption coefficient into dissolved and particulate

    NASA Astrophysics Data System (ADS)

    Ioannou, Ioannis; Foster, Robert; Gilerson, Alex; Ahmed, Sam

    2013-08-01

    We present a method for the separation of the non-algal absorption coefficient into its independent components of dissolved species and non-algal particulate absorptions from remote sensing reflectance (Rrs) measurements in the visible part of the spectrum. This separation is problematic due to the similar absorption spectra of these substances. Due to this complication, we approach the problem by constructing a neural network which relates the remote sensing reflectance at the available MODIS visible wavelengths (412, 443, 488, 531, 547 and 667nm) with the ratio of the absorption coefficient of non-algal particulates to the absorption coefficient of dissolved species, thereby permitting analytical separation of the total non-algal absorption into particulate and dissolved components. The resulting synthetically trained algorithm is tested on simulated data as well as independently on the NASA Bio-Optical Marine Algorithm Data set (NOMAD). Very good agreement is obtained, with R2 values of 87% and 78% for the non-algal particulate and dissolved absorption components, respectively for the NOMAD. Finally, we apply the algorithm to MODIS data and present global distributions for these parameters.

  13. Deformed cross-dissolves for image interpolation in scientific visualization

    Microsoft Academic Search

    Detlef Ruprecht; Fb Informatik Ls

    1994-01-01

    Deformed cross-dissolves are methods for inconspicuous interpolation between images. Wedescribe algorithms for deformation based on scattered data interpolation methods and animproved cross-dissolve algorithm offering better performance than a normal bidirectionalcross-dissolve. Results for interpolation in the field of medical visualization are presented.1 IntroductionImage interpolation has applications in scientific applications as well as in computer animation.In computer...

  14. 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 temperatures.

  15. Scattering measurements from a dissolving bubble.

    PubMed

    Kapodistrias, George; Dahl, Peter H

    2012-06-01

    A laboratory-scale study on acoustic scattering from a single bubble undergoing dissolution in undersaturated fresh water is presented. Several experiments are performed with the acoustic source driven with five-cycle tone bursts, center frequency of 120 kHz, to insonify a single bubble located on axis of the combined beam of the set of transducers. The bubble is placed on a fine nylon thread located in the far field of the transducer set, arranged in bistatic configuration, in a tank filled with undersaturated water. Backscattered waveforms from the bubble target are acquired every few seconds for several hours until the bubble has completely dissolved, and detailed dissolution curves are produced from the acoustic data. The rate of bubble dissolution is calculated using the solution developed by Epstein and Plesset [J. Chem. Phys. 18, 1505-1509 (1950)]. The results of the experiments performed are in agreement with the calculations. PMID:22712899

  16. Method for dissolving delta-phase plutonium

    DOEpatents

    Karraker, David G. (1600 Sherwood Pl., SE., Aiken, SC 29801)

    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.

  17. 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 otherwise addressed.

  18. 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...

  19. Assessing the bioavailability of dissolved organic phosphorus in pasture and cultivated soils treated with different rates of nitrogen fertiliser

    Microsoft Academic Search

    R. W. McDowell; G. F. Koopmans

    2006-01-01

    A proportion of dissolved organic phosphorus (DOP) in soil leachates is readily available for uptake by aquatic organisms and, therefore, can represent a hazard to surface water quality. A study was conducted to characterise DOP in water extracts and soil P fractions of lysimeter soils (pasture before and after, and cultivated soil after leaching to simulate a wet winter–autumn) from

  20. 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

  1. Analysis of mercury in simulated nuclear waste

    SciTech Connect

    Policke, T.A.; Johnson, L.C.; Best, D.R.

    1991-01-01

    Mercury, Hg, is a non-radioactive component in the High Level Waste at the Savannah River Site (SRS). Thus, it is a component of the Defense Waste Processing Facility's (DWPF) process streams. It is present because mercuric nitrate (Hg(NO{sub 3}){sub 2}) is used to dissolve spent fuel rods. Since mercury halides are extremely corrosive, especially at elevated temperatures such as those seen in a melter (1150{degrees}C), its concentration throughout the process needs to be monitored so that it is at an acceptable level prior to reaching the melter off-gas system. The Hg can be found in condensates and sludge feeds and throughout the process and process lines, i.e., at any sampling point. The different samples types that require Hg determinations in the process streams are: (1) sludges, which may be basic or acidic and may or may not include aromatic organics, (2) slurries, which are sludges with frit and will always contain organics (formate and aromatics), and (3) condensates, from feed prep and melter off-gas locations. The condensates are aqueous and the mercury may exist as a complex mixture of halides, oxides, and metal, with levels between 10 and 100 ppm. The mercury in the sludges and slurries can be Hg{sup 0}, Hg{sup +1}, or Hg{sup +2}, with levels between 200 and 3000 ppm, depending upon the location, both time and position, of sampling. For DWPF, both total and soluble Hg concentrations need to be determined. The text below describes how these determinations are being made by the Defense Waste Processing Technology (DWPT) Analytical Laboratory at the Savannah River Site. Both flame atomic absorption (FAA) and cold vapor atomic (CVAA) measurements are discussed. Also, the problems encountered in the steps toward measuring HG in these samples types of condensates and sludges are discussed along with their solutions.

  2. Analysis of mercury in simulated nuclear waste

    SciTech Connect

    Policke, T.A.; Johnson, L.C.; Best, D.R.

    1991-12-31

    Mercury, Hg, is a non-radioactive component in the High Level Waste at the Savannah River Site (SRS). Thus, it is a component of the Defense Waste Processing Facility`s (DWPF) process streams. It is present because mercuric nitrate (Hg(NO{sub 3}){sub 2}) is used to dissolve spent fuel rods. Since mercury halides are extremely corrosive, especially at elevated temperatures such as those seen in a melter (1150{degrees}C), its concentration throughout the process needs to be monitored so that it is at an acceptable level prior to reaching the melter off-gas system. The Hg can be found in condensates and sludge feeds and throughout the process and process lines, i.e., at any sampling point. The different samples types that require Hg determinations in the process streams are: (1) sludges, which may be basic or acidic and may or may not include aromatic organics, (2) slurries, which are sludges with frit and will always contain organics (formate and aromatics), and (3) condensates, from feed prep and melter off-gas locations. The condensates are aqueous and the mercury may exist as a complex mixture of halides, oxides, and metal, with levels between 10 and 100 ppm. The mercury in the sludges and slurries can be Hg{sup 0}, Hg{sup +1}, or Hg{sup +2}, with levels between 200 and 3000 ppm, depending upon the location, both time and position, of sampling. For DWPF, both total and soluble Hg concentrations need to be determined. The text below describes how these determinations are being made by the Defense Waste Processing Technology (DWPT) Analytical Laboratory at the Savannah River Site. Both flame atomic absorption (FAA) and cold vapor atomic (CVAA) measurements are discussed. Also, the problems encountered in the steps toward measuring HG in these samples types of condensates and sludges are discussed along with their solutions.

  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 used a simulant with much lower concentrations of salts, representing washed sludge, and this test produced much smaller amounts of benzene. The nitrite ions in the simulant were oxidized to nitrate, which would increase the amount of peroxide required to oxidize all of the organic carbon. Oxygen is the primary constituent of the off-gas produced from treatment of the samples.

  4. Removal of Dissolved VOCs from Water with an Air Stripper\\/Membrane Vapor Separation System

    Microsoft Academic Search

    J. G. Wijmans; H. D. Kamaruddin; S. V. Segelke; M. Wessling; R. W. Baker

    1997-01-01

    Treatment of water contaminated with volatile organic compounds (VOCs) is a major problem for the United States chemical industry. Currently, VOCs are removed from moderately contaminated wastewater streams by processes such as steam stripping and from dilute wastewaters by air stripping combined with a carbon adsorption off-gas treatment system. This paper describes the development and performance of a hybrid process

  5. 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.

  6. The Minnesota Filter: A Tool for Capturing Stormwater Dissolved Phosphorus

    E-print Network

    Minnesota, University of

    treatment practices provide: ­ Filtration (solids) ­ Infiltration (solids, dissolved?) ­ Sedimentation://stormwater.safl.umn.edu/ Dissolved Pollutant Removal Processes · Vegetative processes: plant uptake and rhizospheric activity to nitrogen gas or petroleum hydrocarbons to carbon dioxide #12;http://stormwater.safl.umn.edu/ Phosphorus

  7. A bulk silicon dissolved wafer process for microelectromechanical devices

    Microsoft Academic Search

    Yogesh B. Gianchandani; Khalil Najafi

    1992-01-01

    A single-sided bulk silicon dissolved wafer process that has been used to fabricate several different micromechanical structures is described. It involves the simultaneous processing of a glass wafer and a silicon wafer, which are eventually bonded together electrostatically. The silicon wafer is then dissolved to leave heavily boron doped devices attached to the glass substrate. Overhanging features can be fabricated

  8. 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 ...

  9. Water injection may spark Po River Delta's dissolved gas play

    Microsoft Academic Search

    G. C. Borgia; G. Brighenti; D. Vitali

    1983-01-01

    The high price of gas may trigger resumption of dissolved gas production from the Po River Delta, stopped in the early 1960s because of excessive subsidence. A contributing factor leading to a reexamination of the problem is the Japanese experience with dissolved gas production in which the injection of produced water separated from the gas overcame the subsidence problem. Additional

  10. Relating dissolved organic matter fluorescence and functional properties

    Microsoft Academic Search

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

    2008-01-01

    The fluorescence excitation–emission matrix properties of 25 dissolved organic matter samples from three rivers and one lake are analysed. All sites are sampled in duplicate, and the 25 samples include ten taken from the lake site, and nine from one of the rivers, to cover variations in dissolved organic matter composition due to season and river flow. Fluorescence properties are

  11. ORIGINAL PAPER Effect of Dissolved Organic Carbon and Alkalinity

    E-print Network

    Hansell, Dennis

    ORIGINAL PAPER Effect of Dissolved Organic Carbon and Alkalinity on the Density of Arctic Ocean that is needed to determine its thermodynamic properties. Density (q), total alkalinity (TA), and dissolved Seawater. This excess is due to the higher values of the normalized total alkalinity (NTA = TA * 35/S) (up

  12. Dissolved organic carbon export with North Pacific Intermediate Water formation

    E-print Network

    Hansell, Dennis

    : Biological and Chemical: Carbon cycling; 4805 Oceanography: Biological and Chemical: Biogeochemical cycles vertical gradient of dissolved inorganic carbon. Dissolved organic carbon (DOC) can also contribute overturning cells [Talley, 1999] are probable key pathways for long-term carbon seques- tration via DOC

  13. The release of dissolved nutrients and metals from coastal sediments due to resuspension

    USGS Publications Warehouse

    Kalnejais, Linda H.; Martin, W. R.; Bothner, Michael H.

    2010-01-01

    Coastal sediments in many regions are impacted by high levels of contaminants. Due to a combination of shallow water depths, waves, and currents, these sediments are subject to regular episodes of sediment resuspension. However, the influence of such disturbances on sediment chemistry and the release of solutes is poorly understood. The aim of this study is to quantify the release of dissolved metals (iron, manganese, silver, copper, and lead) and nutrients due to resuspension in Boston Harbor, Massachusetts, USA. Using a laboratory-based erosion chamber, a range of typical shear stresses was applied to fine-grained Harbor sediments and the solute concentration at each shear stress was measured. At low shear stress, below the erosion threshold, limited solutes were released. Beyond the erosion threshold, a release of all solutes, except lead, was observed and the concentrations increased with shear stress. The release was greater than could be accounted for by conservative mixing of porewaters into the overlying water, suggesting that sediment resuspension enhances the release of nutrients and metals to the dissolved phase. To address the long-term fate of resuspended particles, samples from the erosion chamber were maintained in suspension for 90. h. Over this time, 5-7% of the particulate copper and silver was released to the dissolved phase, while manganese was removed from solution. Thus resuspension releases solutes both during erosion events and over a longer timescale due to reactions of suspended particles in the water column. The magnitude of the annual solute release during erosion events was estimated by coupling the erosion chamber results with a record of bottom shear stresses simulated by a hydrodynamic model. The release of dissolved copper, lead, and phosphate due to resuspension is between 2% and 10% of the total (dissolved plus particulate phase) known inputs to Boston Harbor. Sediment resuspension is responsible for transferring a significant quantity of solid phase metals to the more bioavailable and mobile dissolved phase. The relative importance of sediment resuspension as a source of dissolved metals to Boston Harbor is expected to increase as continuing pollutant control decreases the inputs from other sources. ?? 2010 Elsevier B.V.

  14. Observation of water dangling OH bonds around dissolved nonpolar groups

    PubMed Central

    Perera, P. N.; Fega, K. R.; Lawrence, C.; Sundstrom, E. J.; Tomlinson-Phillips, J.; Ben-Amotz, Dor

    2009-01-01

    We report the experimental observation of water dangling OH bonds in the hydration shells around dissolved nonpolar (hydrocarbon) groups. The results are obtained by combining vibrational (Raman) spectroscopy and multivariate curve resolution (MCR), to reveal a high-frequency OH stretch peak arising from the hydration shell around nonpolar (hydrocarbon) solute groups. The frequency and width of the observed peak is similar to that of dangling OH bonds previously detected at macroscopic air–water and oil–water interfaces. The area of the observed peak is used to quantify the number of water dangling bonds around hydrocarbon chains of different length. Molecular dynamics simulation of the vibrational spectra of water molecules in the hydration shell around neopentane and benzene reveals high-frequency OH features that closely resemble the experimentally observed dangling OH vibrational bands around neopentyl alcohol and benzyl alcohol. The red-shift of ?50 cm?1 induced by aromatic solutes is similar to that previously observed upon formation of a ?-H bond (in low-temperature benzene–water clusters). PMID:19620734

  15. Dissolved gas quantification and bubble formation in liquid chemical dispense

    NASA Astrophysics Data System (ADS)

    Tom, Glenn; Liu, Wei

    2009-12-01

    Gas dissolved in liquids such as photoresist comes out of solution as bubbles after the liquid experiences a pressure drop in a dispense train and may cause on-wafer defects. Reservoirs in the dispense train can assist in removing bubbles but are incapable of effectively removing dissolved gas. This study demonstrates the importance of maintaining the amount of dissolved gas in a liquid below a critical value to reduce bubbles generated after a pressure drop in the dispense train occurs. The methodology used to quantify dissolved gas during liquid dispense cycle using gas chromatography is discussed. The amount of dissolved gas is correlated to the amount of bubbles downstream of a pressure drop. This study also analyzes sources of bubbles in the dispense train and techniques to mediate the sources.

  16. 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)

  17. A Fluorescence Based Dissolved Oxygen Sensor

    NASA Astrophysics Data System (ADS)

    McFarlane, Ronald; Hamilton, M. Coreen

    1987-10-01

    A sensor based on fluorescence quenching has been built to detect oxygen activity in gas and water. The sensor consists of a xenon flash bulb as a light source; an excitation wavelength band pass filter; a dichroic beam splitter; collimating and focussing lenses; a plastic clad silica (PCS) rod with the fluorophore immobilized at the tip of it; an emission wavelength band pass filter; a photomultiplier tube (PMT); a monitor PIN photodiode detector; and interface electronics to couple a computer to the rest of the sensor. The device demonstrates a reversible change in fluorescence quenching for changes in oxygen activity. The fluorescence signal seen by the PMT varies over a factor of 3, being highest at 0 oxygen activity and lowest at atmospheric oxygen activity. The device exhibits a 63 % response time of less than 1 second for gases and less than 10 seconds for oxygen dissolved in water. The noise floor of the sensor is approximately 1%. The present embodiment of the device was designed to allow the sensor to operate in the marine environment. The optical components, computer, batteries, and power supply circuitry are mounted on a rack that is enclosed in a pressure housing. The immobilized fluorophore is exposed to sea water. The light travels along the PCS rod, through a pressure seal, to the rest of the system. Present investigations are centered around long term stability of the fluorophore and constituents of the real ocean that will interfere with the quenching mechanism.

  18. Dissolved Humic Matter in Arctic Estuaries

    NASA Astrophysics Data System (ADS)

    Spitzy, A.; Koehler, H.; Ertl, S.

    2002-12-01

    As part of the German-Russian bilateral SIRRO(Siberian River Runoff)-project we studied the distribution of dissolved humic matter isolated by XAD-8 in the estuarine waters of the Ob and Yenisei rivers. The relative contributions of humic matter carbon to total DOC decreased from 61-77 percent in the river freshwater endmember to 35-40 percent in the marine waters of the open Kara Sea at salinities 33 psu. Humic carbon mixed conservatively in the Yenisei and non-conservatively in the Ob, where partial removal was indicated in the low salinity range. Changes in the relative contribution of humic matter to different molecular weight classes of DOM (ultrafiltration cutoffs 150 KDa, 450 KDa, 800 KDa) were studied along the salinity gradient in the Yenisei. High molecular weight DOM is relatively enriched in humics in fresh-water compared to sea-water HMW-DOM. Low molecular weight DOM is realtively enriched in humics in sea-water compared to fresh-water LMW-DOM. Throughout the estuary humic matter is depleted in 13C and nitrogen compared to total DOM, reflecting a dominant soil source. We estimate an annual input of 5 Tg humic matter carbon by the two rivers into the Kara Sea.

  19. Distribution of dissolved organic carbon and dissolved fulvic acid in mesotrophic Lake Biwa, Japan

    Microsoft Academic Search

    Yuko Sugiyama; Aya Anegawa; Hiroo Inokuchi; Tetsu Kumagai

    2005-01-01

    The dissolved organic carbon (DOC) concentrations in mesotrophic Lake Biwa were determined by a total organic carbon (TOC)\\u000a analyzer, and DOC molecular size distributions were determined by size exclusion chromatography (SEC) using a fluorescence\\u000a detector at excitation\\/emission (Ex\\/Em) levels of 300\\/425?nm with the eluent at pH 9.7. The fluorescence wavelengths for detection\\u000a were chosen from the result of excitation–emission matrix

  20. Chemical characterization of dissolvable tobacco products promoted to reduce harm.

    PubMed

    Rainey, Christina L; Conder, Paige A; Goodpaster, John V

    2011-03-23

    In 2009, the R. J. Reynolds Tobacco Co. released a line of dissolvable tobacco products that are marketed as an alternative to smoking in places where smoking is prohibited. These products are currently available in Indianapolis, IN, Columbus, OH, and Portland, OR. This paper describes the chemical characterization of four such products by gas chromatography-mass spectrometry (GC-MS). The dissolvable tobacco products were extracted and prepared by ultrasonic extraction using acetone, trimethylsilyl derivatization, and headspace solid phase microextraction (SPME). The following compounds were identified in the dissolvables using either ultrasonic extractions or trimethylsilyl derivatization: nicotine, ethyl citrate, palmitic acid, stearic acid, sorbitol, glycerol, and xylitol. The following compounds were identified in the dissolvables using headspace SPME: nicotine, ethyl citrate, cinnamaldehyde, coumarin, vanillin, and carvone. With the exception of nicotine, the compounds identified thus far in the dissolvables are either flavoring compounds or binders. The concentration of free nicotine in the dissolvables was determined from the Henderson-Hasselbalch equation and by measuring the pH and nicotine concentration by GC-MS. The results presented here are the first to reveal the complexity of dissolvable tobacco products and may be used to assess potential oral health effects. PMID:21332188

  1. Optimizing dissolved air flotation design and saturation.

    PubMed

    Féris, L A; Gallina, C W; Rodrigues, R T; Rubio, J

    2001-01-01

    Dissolved air flotation (DAF) of iron hydroxide precipitates at working pressures lower than 3 atm, using modified flotation units to improve the collection of fragile coagula, was studied. Conventional DAF flotation was studied as a function of saturation pressure in the absence and presence of surfactants in the saturator. Without surfactants, the minimum saturation pressure required for DAF to occur was found to be 3 atm. But, by lowering the air/water surface tension in the saturator, DAF was possible at a saturation pressure of 2 atm. This behavior was found to occur in both batch and pilot DAF operation tests and almost complete recovery of the precipitates was attained. Results are explained in terms of the minimum "energy" which has to be transferred to the liquid phase to form bubbles by a cavity phenomenon. Further, studies were conducted changing equipment design and feed bubbles size distribution (mixing micro and "mid-sized" bubbles). Thus, bubbles entrance position in the collision-adhesion zone ("capture" zone) was compared to bubble entrance position in the water flow inlet below the floating bed. A "mushroom" type diffuser was used for the "capture zone" experiment and better performance was obtained. Results are explained in terms of different mass transfer phenomena in the collection zone and in the separation zone. Finally, results obtained with the use of a column flotation cell working as normal DAF and with a wide bubble size range are presented. Results indicate good performance and some gains in process kinetics with middle size bubbles. PMID:11394267

  2. 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.

  3. 7 CFR 1413.113 - Deceased individuals or dissolved entities.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...CORPORATION, DEPARTMENT OF AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS COMMODITY INCENTIVE PAYMENT PROGRAMS Durum Wheat Quality Program § 1413.113 Deceased individuals or dissolved entities. (a) Payment may be made for an...

  4. 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.

  5. Hidden cycle of dissolved organic carbon in the deep ocean

    E-print Network

    Repeta, Daniel J.

    Marine dissolved organic carbon (DOC) is a large (660 Pg C) reactive carbon reservoir that mediates the oceanic microbial food web and interacts with climate on both short and long timescales. Carbon isotopic content ...

  6. The marine biogeochemistry of dissolved and colloidal iron

    E-print Network

    Fitzsimmons, Jessica Nicole

    2013-01-01

    Iron is a redox active trace metal micronutrient essential for primary production and nitrogen acquisition in the open ocean. Dissolved iron (dFe) has extremely low concentrations in marine waters that can drive phytoplankton ...

  7. EFFECTS OF TEMPERATURE VARIATION ON CRITICAL STREAM DISSOLVED OXYGEN

    EPA Science Inventory

    The classical assumption that the lowest dissolved oxygen (DO) occurs at the highest temperature may not always hold. The DO saturation concentration decreases monotonically with increasing temperature, lowering the DO, but the reaeration coefficient increases monotonically with ...

  8. Microbial production and consumption of marine dissolved organic matter

    E-print Network

    Becker, Jamie William

    2013-01-01

    Marine phytoplankton are the principal producers of oceanic dissolved organic matter (DOM), the organic substrate responsible for secondary production by heterotrophic microbes in the sea. Despite the importance of DOM in ...

  9. 7 CFR 1413.113 - Deceased individuals or dissolved entities.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...CORPORATION, DEPARTMENT OF AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS COMMODITY INCENTIVE PAYMENT PROGRAMS Durum Wheat Quality Program § 1413.113 Deceased individuals or dissolved entities. (a) Payment may be made for an...

  10. 7 CFR 1413.113 - Deceased individuals or dissolved entities.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...CORPORATION, DEPARTMENT OF AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS COMMODITY INCENTIVE PAYMENT PROGRAMS Durum Wheat Quality Program § 1413.113 Deceased individuals or dissolved entities. (a) Payment may be made for an...

  11. 7 CFR 1413.113 - Deceased individuals or dissolved entities.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...CORPORATION, DEPARTMENT OF AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS COMMODITY INCENTIVE PAYMENT PROGRAMS Durum Wheat Quality Program § 1413.113 Deceased individuals or dissolved entities. (a) Payment may be made for an...

  12. DOES DISSOLVED INORGANIC CARBON PLAY A ROLE IN ARSENIC MOBILIZATION?

    EPA Science Inventory

    Recent experimental results provide evidence that dissolved inorganic carbon plays a direct role in mobilizing arsenic in anoxic aquatic environments. This hypothesis is partially supported by observed correlations between elevated levels of arsenic and alkalinity in a ground wa...

  13. Fate of dissolved organic nitrogen in two stage trickling filter process.

    PubMed

    Simsek, Halis; Kasi, Murthy; Wadhawan, Tanush; Bye, Christopher; Blonigen, Mark; Khan, Eakalak

    2012-10-15

    Dissolved organic nitrogen (DON) represents a significant portion of nitrogen in the final effluent of wastewater treatment plants (WWTPs). Biodegradable portion of DON (BDON) can support algal growth and/or consume dissolved oxygen in the receiving waters. The fate of DON and BDON has not been studied for trickling filter WWTPs. DON and BDON data were collected along the treatment train of a WWTP with a two-stage trickling filter process. DON concentrations in the influent and effluent were 27% and 14% of total dissolved nitrogen (TDN). The plant removed about 62% and 72% of the influent DON and BDON mainly by the trickling filters. The final effluent BDON values averaged 1.8 mg/L. BDON was found to be between 51% and 69% of the DON in raw wastewater and after various treatment units. The fate of DON and BDON through the two-stage trickling filter treatment plant was modeled. The BioWin v3.1 model was successfully applied to simulate ammonia, nitrite, nitrate, TDN, DON and BDON concentrations along the treatment train. The maximum growth rates for ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria, and AOB half saturation constant influenced ammonia and nitrate output results. Hydrolysis and ammonification rates influenced all of the nitrogen species in the model output, including BDON. PMID:22835838

  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. 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)

  16. Variable gain CMOS potentiostat for dissolved oxygen sensor

    Microsoft Academic Search

    Mei Yee Ng; Yuzman Yusoff

    2010-01-01

    This paper presents a variable gain potetiostat designed for the electrochemical control of Dissolved Oxygen (DO) sensors. The design is targeted for implementation using MIMOS 0.35 um CMOS process technology at 3.3V. The potentiostat amplifier for dissolved oxygen utilizes three electrodes (working, reference and counter) which work together to form the electrochemical reaction. There are several types of DO sensor

  17. Dissolved Oxygen Online Acquisition Terminal Based on Wireless Sensor Network

    Microsoft Academic Search

    Meijuan Gao; Fan Zhang; Jingwen Tian

    2008-01-01

    Dissolved oxygen (DO) is an important indicator of the water quality in the modern sewage treatment It reflects the degree of self-purification capacity of the water. In this paper, we proposed a kind of wireless sensor network-based dissolved oxygen online collection terminal. The terminal, with the core of ARM (Advanced RISC Machines) microprocessor, combines of multi-sensor data fusion technology and

  18. The freshwater dissolved organic matter fluorescence total organic carbon relationship

    Microsoft Academic Search

    Susan A. Cumberland; Andy Baker

    2007-01-01

    The fluorescent properties of dissolved organic matter (DOM) enable comparisons of humic-like (H-L) and fulvic-like (F-L) fluorescence intensities with dissolved organic carbon (DOC) in aquatic systems. The fluorescence-DOC relationship differed in gradient, i.e. the fluorescence per gram of carbon, and in the strength of the correlation coefficient. We compare the fluorescence intensity of the F-L and H-L fractions and DOC

  19. 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 metal may be transferred from phytoplankton through food webs vis à vis grazing by zooplankton or other pathways. PMID:25337629

  20. 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

  1. 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

  2. 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

  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. 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.

  5. FINAL REPORT INTEGRATED DM1200 MELTER TESTING OF REDOX EFFECTS USING HLW AZ-101 AND C-106\\/AY102 SIMULANTS VSL-04R4800-1 REV 0 5\\/6

    Microsoft Academic Search

    KRUGER AA; MATLACK KS; GONG W; BARDAKCI T; DANGELO NA; LUTZE W; BIZOT PM; CALLOW RA; BRANDYS M; KOT WK; PEGG IL

    2011-01-01

    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,

  6. Chemical and Isotopic Characterization of Rainwater Dissolved Organic Carbon and Chromophoric Dissolved Organic Matter

    NASA Astrophysics Data System (ADS)

    Avery, G. B.; Kieber, R. J.; Willey, J. D.; Seaton, P. J.

    2007-05-01

    Chromophoric dissolved organic matter (CDOM) is a ubiquitous, integral component of atmospheric waters which comprises a significant fraction of the dissolved organic carbon (DOC) pool in the condensed phase. The presence of significant quantities of highly chromophoric DOM in atmospheric waters has profound ramifications with respect to a wide variety of fundamental processes in atmospheric chemistry because of its impact on solar radiative transfer and its involvement in the oxidizing and acid generating capacity of the troposphere. Initial isotopic characterization (13C, 14C, 15N) of CDOM will be presented which provides information on origin as well as transport and cycling of CDOM though the atmosphere. We have determined 4-24 percent of DOC is of fossil fuel origin and that rain DOC can be terrestrial, marine or a combination of the two depending on air mass back trajectory. The C:N ratio as well as nuclear magnetic resonance 1H-NMR spectra of extracted CDOM from terrestrial and marine origin indicate a relatively continuous and broad distribution of signals, suggesting the presence of complex mixtures of compounds. The DOC concentration of rainwater has decreased approximately 50 percent since 1995. 13C and 14C signatures of rain DOC indicates that in 1997-1998 up to 24 percent of Wilmington rainwater DOC was from fossil fuel origin. Comparison of fossil fuel contributions of CDOM and DOC will help determine what fraction of the loss of rainwater DOC results from changing fossil fuel inputs and what role if any CDOM plays in these changes.

  7. Seasonal Changes in Arctic Dissolved Organic Matter

    NASA Astrophysics Data System (ADS)

    Boot, C. M.; Wallenstein, M. D.; Schimel, J.

    2011-12-01

    The Arctic is a landscape in flux. Temperatures are shifting upward and plant communities are transitioning from tussock to shrub tundra in some regions. Decomposition processes sensitive to temperature, moisture, and plant inputs are controls on the source/sink dynamics of the Arctic C pool. The response of decomposition to warming will, in part, determine if the Arctic C pool feeds back positively or negatively to climate change. The portion of the C pool immediately available to decomposers is dissolved organic matter (DOM). The aim of this is study is to examine the molecular composition of DOM to determine which components vary seasonally in soil pore water among three vegetation types at Toolik Field Station in Alaska. Vegetation types include wet sedge (Carex aquatilis and Eriophorum angustifolium), moist acidic tussock (E. vaginatum) and shrub tundra (Betula nana and Salix sp.). These sites were sampled during winter/summer transitions in 2010 in order to capture both growing season and winter dynamics. We expected the chemical composition of DOM in pore water to be distinct among plant communities due to differences in root exudates, litter chemistry and microbial community; and vary seasonally due to shifting temperature and water availability and their impacts on decomposition of DOM. Soil pore water was isolated through centrifugation and is being characterized with ultra high performance liquid chromatography (UPLC) in line with a quadrupole time of flight mass spectrometer (QTOF-MS) as well as with specific UV absorbance at 254 nm (SUVA), and excitation emission matrices (EEMs) generated by fluorescence spectroscopy. The DOM concentrations across vegetation types show consistent seasonal patterns, spiking at thaw, and declining through late summer. As soils freeze these patterns diverge-in tussock soils DOM concentration decreases slightly, while in shrub and wet sedge sites it increases. SUVA values (indicator of aromaticity) were consistent among vegetation types across seasons; starting low in late winter and at thaw, increasing over the course of the summer and decreasing at the summer to winter transition. Metabolite profiles generated with UPLC-MS were evaluated using principle component analysis. Sampling date explained the most variation in this dataset, with metabolite profiles of the DOM most different in the summer to winter transition. Over 6000 mass features were detected in the metabolite profiles and at least 1500 of these features were significantly different between late summer and early winter. Fluorescence EEMs have been collected for the complete dataset and analysis is underway. Overall, these data suggest the composition of DOM varies more due to season than vegetation type, with changes in quantity, aromaticity, and shifts in the metabolite profiles occurring at seasonal transitions. Efforts are continuing to identify some of the most variable components with MS and EEMs data. By understanding which chemical components of DOM shift seasonally, we can anticipate what portions of the DOM are most subject to change in a warming arctic; and how the gain/loss of those components will play into the sink/source C dynamics under future climate scenarios.

  8. Photoproduction of dissolved inorganic carbon in temperate and tropical lakes – dependence on wavelength band and dissolved organic carbon concentration

    Microsoft Academic Search

    Måns Lindell; Bias Marçal de Faria; Francisco de Assis Esteves

    1998-01-01

    We have evaluated photoeffects of UV-B, UV-A and PAR radiation on dissolved organic matter (DOM). Photochemical production of dissolved inorganic carbon (DIC) was measured in sterile lake water from Sweden and Brazil after 6 hours of sun exposure. Tubes were exposed to four solar radiation regimes: Full-radiation, Full-radiation minus UV-B, Full-radiation minus UV-B and UV-A (PAR) and darkness.

  9. Risks posed to drinking water aquifers due to leakage of dissolved CO2 in improperly abandoned wellbores

    NASA Astrophysics Data System (ADS)

    Ellison, Kirk Matthew

    In order to ensure safe long-term storage of carbon dioxide in geologic formations, the risks posed by improperly abandoned wells must be understood and minimalized. In addition to supercritical and gaseous CO2, brine containing dissolved CO2 poses a leakage risk. CO2 dissolution in brine leads to denser brine and better long-term storage security, but its leakage risk is not zero. Under specific circumstances with formation overpressure or overlying aquifer drawdown, dissolved brine can flow up improperly abandoned wells where it can potentially enter and contaminate drinking water aquifers. The possibility that depressurization in the wellbore may cause CO2 exsolution from brine to form a separate buoyant gas phase is of primary concern. Analytical as well as numerical models are used to evaluate these effects in wellbores as well as to examine the effects of system parameters on brine leakage rates through wellbores. A simple analytical model for uniform density flow is used to evaluate the effects of physical parameters on fluid leakage. It is a useful screening tool for estimating leading order effects of system parameters on leakage of CO2 laden brine. The TOUGH2-ECO2N simulator is also used to evaluate wellbore leakage of dissolved CO2 considering gas exsolution due to pressure, temperature, phase, and salinity changes. Simulations identify the conditions under which a separate gas phase exsolves in a wellbore during CO2 laden brine leakage. Up to 20% of the dissolved brine is found to exsolve in the numerical simulations. This gas accumulates along the top of a drinking water aquifer as a buoyant phase. Simulations also show that the degree of leakage is constrained by the properties of the well, with the permeability of the well being of chief importance. However, at high well permeabilities, simulations show that the geologic formations provide more resistance to flow than the well and constrain leakage rates. Additional analyses are performed in order to see how dissolved CO2 may leak from a wellbore in a geologic system of stratified permeable layers. It is found that the presence of stratigraphy limits the possibility of upward migration of dissolved CO2, whether through overpressure of drawdown.

  10. Surface segregation of dissolved salt ions.

    PubMed

    Höfft, Oliver; Borodin, Andriy; Kahnert, Uwe; Kempter, Volker; Dang, Liem X; Jungwirth, Pavel

    2006-06-22

    Surface segregation of iodide, but not of fluoride or cesium ions, is observed by a combination of metastable impact electron spectroscopy (MIES) and ultraviolet photoelectron spectroscopy (UPS(HeI)) of amorphous solid water exposed to CsI or CsF vapor. The same surface ionic behavior is also derived from molecular dynamics (MD) simulations of the corresponding aqueous salt solutions. The MIES results show the propensity of iodide, but not fluoride, for the surface of the amorphous solid water film, providing thus strong evidence for the suggested presence of heavier halides (iodide, bromide, and to a lesser extent chloride) at the topmost layer of aqueous surfaces. In contrast, no appreciable surface segregation of ions is observed in methanol, neither in the experiment nor in the simulation. Furthermore, the present results indicate that, as far as the thermodynamic aspects of solvation of alkali halides are concerned, amorphous solid water and methanol surfaces behave similarly as surfaces of the corresponding liquids. PMID:16800503

  11. 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.

    2015-01-01

    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

  12. Relationship between the loading rate of inorganic mercury to aquatic ecosystems and dissolved gaseous mercury production and evasion

    Microsoft Academic Search

    Alexandre J. Poulain; Diane M. Orihel; Marc Amyot; Michael J. Paterson; Holger Hintelmann; George R. Southworth

    2006-01-01

    The purpose of our study was to test the hypothesis that dissolved gaseous mercury (DGM) production and evasion is directly proportional to the loading rate of inorganic mercury [Hg(II)] to aquatic ecosystems. We simulated different rates of atmospheric mercury deposition in 10-m diameter mesocosms in a boreal lake by adding multiple additions of Hg(II) enriched with a stable mercury isotope

  13. The Research about Detection of Dissolved Oxygen in Water Based on C8051F040

    Microsoft Academic Search

    Yu Zhao; Li Sun; Meng-fei Li

    2009-01-01

    Dissolved oxygen (DO) is the molecular oxygen that dissolves in water and it is an indispensable condition for aquatic life to survive. The dissolved oxygen content is closely related to the degree of organic pollution in water, so it is also one of the important parameters to measure the water quality. In this work, a kind of water dissolved oxygen

  14. 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.

  15. Primary production in the Arctic Ocean estimated from dissolved oxygen

    NASA Astrophysics Data System (ADS)

    Pomeroy, Lawrence R.

    1997-01-01

    The deep, central basins of the Arctic Ocean have been thought to support little biological production. However, summer dissolved oxygen data from the upper mixed layer of the ice-covered central Arctic Ocean yield estimates of primary production which are high enough to account for oxygen utilization in the halocline. Thus, it may not be necessary to postulate either that all significant primary production is on or near the continental shelves, or that organic matter is transported along isopycnals over decades of time to support respiration in the halocline over the deep basins. Because dissolved oxygen data are available for many parts of the Arctic Basin, it may be possible to begin to look for regional differences in productivity. It remains true that more primary production is occurring on the extensive continental shelves than in the basins, and some dissolved organic matter produced on continental shelves must be entering the basins via the halocline. Some of that dissolved organic matter may also contribute to secondary production and to the observed oxygen utilization. However, the evidence from dissolved oxygen measurements, as well as from the observations on consumers, from bacteria to bears, suggests the presence of a complete, locally supported food web in the permanently ice-covered regions of the Arctic Ocean.

  16. Modelling Dissolved Pollutants in Krishna River Using Adaptive Neuro Fuzzy Inference Systems

    NASA Astrophysics Data System (ADS)

    Matli, C. S.; Umamahesh, N. V.

    2014-01-01

    Water quality models are used to describe the discharge concentration relationships in the river. Number of models exists to simulate the pollutant loads in a river, of which some of them are based on simple cause effect relationships and others on highly sophisticated physical and mathematical approaches that require extensive data inputs. Fuzzy rule based modeling extensively used in other disciplines, is attempted in the present study for modeling water quality with respect of dissolved pollutants in Krishna river flowing in Southern part of India. Adaptive Neuro Fuzzy Inference Systems (ANFIS), a recent development in the area of neuro-computing, based on the concept of fuzzy sets is used to model highly non-linear relationships and are capable of adaptive learning. This paper presents the results of the application of ANFIS for modeling dissolved pollutants in the Krishna River. The application and validation of the models is carried out using water quality and flow data obtained from the monitoring stations on the river. The results indicate that the models are quite successful in simulating the physical processes of the relationships between discharge and concentrations.

  17. 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

  18. 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

  19. 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

  20. Dissolved Solids in Streams of the Conterminous United States

    NASA Astrophysics Data System (ADS)

    Anning, D. W.; Flynn, M.

    2014-12-01

    Studies have shown that excessive dissolved-solids concentrations in water can have adverse effects on the environment and on agricultural, municipal, and industrial water users. Such effects motivated the U.S. Geological Survey's National Water-Quality Assessment Program to develop a SPAtially-Referenced Regression on Watershed Attributes (SPARROW) model to improve the understanding of dissolved solids in streams of the United States. Using the SPARROW model, annual dissolved-solids loads from 2,560 water-quality monitoring stations were statistically related to several spatial datasets serving as surrogates for dissolved-solids sources and transport processes. Sources investigated in the model included geologic materials, road de-icers, urban lands, cultivated lands, and pasture lands. Factors affecting transport from these sources to streams in the model included climate, soil, vegetation, terrain, population, irrigation, and artificial-drainage characteristics. The SPARROW model was used to predict long-term mean annual conditions for dissolved-solids sources, loads, yields, and concentrations in about 66,000 stream reaches and corresponding incremental catchments nationwide. The estimated total amount of dissolved solids delivered to the Nation's streams is 272 million metric tons (Mt) annually, of which 194 million Mt (71%) are from geologic sources, 38 million Mt (14%) are from road de-icers, 18 million Mt (7%) are from pasture lands, 14 million Mt (5 %) are from urban lands, and 8 million Mt (3%) are from cultivated lands. The median incremental-catchment yield delivered to local streams is 26 metric tons per year per square kilometer [(Mt/yr)/km2]. Ten percent of the incremental catchments yield less than 4 (Mt/yr)/km2, and 10 percent yield more than 90 (Mt/yr)/km2. In 13% of the reaches, predicted flow-weighted concentrations exceed 500 mg/L—the U.S. Environmental Protection Agency secondary non-enforceable drinking-water standard.

  1. Dissolved gas concentrations of the geothermal fluids in Taiwan

    NASA Astrophysics Data System (ADS)

    Chen, Ai-Ti; Yang, Tsanyao Frank

    2010-05-01

    Taiwan, a geologically active island, is located on the boundary of the Philippine Sea Plate and the Eurasian Plate. High heat flow and geothermal gradient generated by the complex collision and orogeny, warm up the meteoric water and/or the ground water. The heated water becomes geothermal fluids. In previous studies, researchers tried to categorize hot springs based on the appearance, chemical compositions and lithological areas. Because of the chemical inertness, the concentrations and isotopic composition of dissolved noble gases are good indicators of the mantle degassing, geothermal conditions, and so on. In this study, 55 hot springs were collected from different tectonic units. It is the first time to systematically study the hot springs in Taiwan in terms of dissolved gases. Hot spring water is sampled and stored in pre-evacuated glass bottles for analyzing gas compositions. The abundances of noble gases were determined by a quadrupole mass spectrometer based on the isotope dilution technique. Samples with glass vials are introduced to RAD 7 and GC for dissolved Rn and major dissolved gases analyses. Furthermore, helium isotopic ratios and helium-neon ratios are measured on a conventional noble gas mass spectrometer. For hydrochemistry analysis, water samples are analyzed by IC, ICP-MS and titration. We can classify the hot springs samples into three major groups from main anion concentration data; and then, subdivide them into nine minor groups by cation concentration data. Moreover, according to major dissolved gases compositions, three major gas components: CH4, N2 and CO2, are identified. Dissolved noble gases provided more detailed clues about hot springs sources in Taiwan, such as the degree of mixing between meteoric water and deep-source water, which will be further discussed in this study.

  2. Water injection may spark Po River Delta's dissolved gas play

    SciTech Connect

    Borgia, G.C.; Brighenti, G.; Vitali, D.

    1983-06-01

    The high price of gas may trigger resumption of dissolved gas production from the Po River Delta, stopped in the early 1960s because of excessive subsidence. A contributing factor leading to a reexamination of the problem is the Japanese experience with dissolved gas production in which the injection of produced water separated from the gas overcame the subsidence problem. Additional impetus comes from the present Italian tendency to exploit marginal resources. This is particularly true of natural gas because an increasing percentage of the Italian energy requirement is being satisfied by gas, and the forecast is that this trend will continue.

  3. 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.

  4. New potentiomentric dissolved oxygen sensors in thick film technology

    Microsoft Academic Search

    Ramón Mart??nez-Máñez; Juan Soto; Josefa Lizondo-Sabater; Eduardo Garc??a-Breijo; Luis Gil; Javier Ibáñez; Isabel Alcaina; Silvia Alvarez

    2004-01-01

    New designed dissolved oxygen potentiometric sensors in thick film technology based in the use of RuO2 as active material and TiO2 or polyisoftalamide diphenylsulphone (PIDS) as membranes have been developed. TiO2-coated RuO2 electrodes showed a linear response as a function of the logarithm of the dissolved oxygen concentration in the 0.5–8ppm range (log[O2], ?4.82 to ?3.60; concentration of O2 in

  5. Biogeochemical interpretations of colored dissolved organic matter optical signatures

    NASA Astrophysics Data System (ADS)

    Stubbins, A.; Spencer, R. G.; Mann, P. J.; Dittmar, T.; Niggemann, J.; Holmes, R. M.; McClelland, J. W.; Del Giorgio, P.; Prairie, Y.; Lapierre, J. F.; Berggren, M.

    2014-12-01

    The optical properties of colored dissolved organic matter (CDOM) in surface waters are visible from space and observable throughout the water column in real time using in situ sensors. Due to their ease of measurement, CDOM optical properties are used as proxies for the quantity, quality and processing of dissolved organic matter (DOM) in natural waters. This talk will focus upon the use of these optical signatures to provide insight into the cycling of DOM. Examples will include the use of color to estimate quantitative fluxes and the molecular composition of organics in natural waters.

  6. Characterizing the release of different composition of dissolved organic matter in soil under acid rain leaching using three-dimensional excitation–emission matrix spectroscopy

    Microsoft Academic Search

    Li Liu; Cunyi Song; Zengguang Yan; Fasheng Li

    2009-01-01

    Although excitation–emission matrix spectroscopy (EEMS) has been widely used to characterize dissolved organic matter (DOM), there has no report that EEMS has been used to study the effects of acid rain on DOM and its composition in soil. In this work, we employed three-dimensional EEMS to characterize the compositions of DOM leached by simulated acid rain from red soil. The

  7. 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 consequence of reducing the viscosity of the pyroclasts and, more importantly, reducing Tg. The reduction in pyroclast viscosity facilitates sintering, welding and compaction processes. The reduced Tg, due to resorbed H2O, extends the T-time window for porosity reduction via viscous flow. Variations in welding intensity can, therefore, be an expression of the competition between cooling of the deposit and the re-hydration of vitric pyroclasts during cooling driven by retrograde solubility of H2O. In essence, the temperature of the cooling deposit chases a descending Tg; once the deposit temperature catches and drops below Tg, viscous deformation processes are quenched. This allows for the H2O contents of vitric pyroclasts to preserve higher water contents that they had at the time they erupted. The analysis of the relationships between eruptive, emplacement and glass transition temperatures are discussed further. References Cited: Behrens H. et al. 2009: Am Min 94, 105-120. Di Matteo V. et al. 2004: Chemical Geology 213, 187-196. Liu Y et al. 2005: . J Volc Geotherm Res 143, 219-235. Zhang Y 1999: Rev Geophys 37, 493-516.

  8. Fiber-optic dissolved oxygen and dissolved carbon dioxide sensors using fluorophores encapsulated in sol gel matrices

    Microsoft Academic Search

    Hyeog-Chan Kwon

    2002-01-01

    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

  9. 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...

  10. DISSOLVED OXYGEN MEASUREMENTS IN INDIANA STREAMS DURING URBAN RUNOFF

    EPA Science Inventory

    This short term research project was undertaken for the purpose of locating and identifying sites where potential dissolved oxygen (D.O.) impacts exist during periods of urban runoff, and providing the necessary information to justify more extensive D.O. model verification studie...

  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. Chloride Analysis of RFSA Second Campaign Dissolver Solution

    SciTech Connect

    Holcomb, H.P.

    2001-05-17

    The dissolver solution from the second RFSA campaign was analyzed for chloride using the recently-developed turbidimetric method. Prior to chloride removal in head end, the solution contained 1625 ppm chloride. After chloride removal with Hg(I) and prior to feeding to solvent extraction, the solution contained only 75 ppm chloride. This report discusses those analysis results.

  14. 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...

  15. 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...

  16. Dependence of riverine nitrous oxide emissions on dissolved oxygen levels

    NASA Astrophysics Data System (ADS)

    Rosamond, Madeline S.; Thuss, Simon J.; Schiff, Sherry L.

    2012-10-01

    Nitrous oxide is a potent greenhouse gas, and it destroys stratospheric ozone. Seventeen per cent of agricultural nitrous oxide emissions come from the production of nitrous oxide in streams, rivers and estuaries, in turn a result of inorganic nitrogen input through leaching, runoff and sewage. The Intergovernmental Panel on Climate Change and global nitrous oxide budgets assume that riverine nitrous oxide emissions increase linearly with dissolved inorganic nitrogen loads, but data are sparse and conflicting. Here we report measurements over two years of nitrous oxide emissions in the Grand River, Canada, a seventh-order temperate river that is affected by agricultural runoff and outflow from a waste-water treatment plant. Emissions were disproportionately high in urban areas and during nocturnal summer periods. Moreover, annual emission estimates that are based on dissolved inorganic nitrogen loads overestimated the measured emissions in a wet year and underestimated them in a dry year. We found no correlations of nitrous oxide emissions with nitrate or dissolved inorganic nitrogen, but detected negative correlations with dissolved oxygen, suggesting that nitrate concentrations did not limit emissions. We conclude that future increases in nitrate export to rivers will not necessarily lead to higher nitrous oxide emissions, but more widespread hypoxia most likely will.

  17. Development of a reliable microelectrode dissolved oxygen sensor

    Microsoft Academic Search

    Maciej Sosna; Guy Denuault; Robin W. Pascal; Ralf D. Prien; Matt Mowlem

    2007-01-01

    This article reports the results of a careful experimental and analytical investigation which led to the development of an accurate and reproducible microelectrode dissolved oxygen sensor. Primarily designed for oceanographic applications but also applicable to environmental and water process monitoring, the sensor measures the diffusion controlled current to a bare Pt microdisc electrode for the reduction of oxygen. A successful

  18. U-shaped plastic optical fiber dissolved oxygen sensor

    Microsoft Academic Search

    Haiwen Cai; Fenghong Chu; Ronghui Qu; Zujie Fang

    2008-01-01

    A dissolved oxygen sensor based on U-shape plastic optical fiber (POF) was described. Analyte-sensitive fluorophore are entrapped into ormosil film by using Sol-gel method. Phase modulation technique is used to measure fluorescence lifetime. The influence of oxygen indictor concentration, annealing time and U-shaped POF curve radius on the systems sensitivity is studied.

  19. Micromachined dissolved oxygen sensor based on solid polymer electrolyte

    Microsoft Academic Search

    Peng Wang; Yi Liu; Héctor D. Abruña; Jason A. Spector; William L. Olbricht

    2011-01-01

    A silicon microprobe to measure dissolved oxygen levels is described. The sensors are prepared by overlaying platinum thin film electrodes with a solid state proton conductive matrix (PCM) coating. The platinum thin film electrodes are fabricated on silicon substrates by standard photolithographic techniques while the PCM coating is achieved by drop-casting methods. The size and materials of the device make

  20. Comparison of the dynamics of hydrogen and deuterium dissolved in

    Microsoft Academic Search

    T. J. Udovic; C. Karmonik; Q. Huang; J. J. Rush; M. Vennstrom; Y. Andersson; T. B. Flanagan

    The bonding potentials of hydrogen and deuterium dissolved in the crystalline alloys Pd Si and Pd P have been studied by neutron 9 2 3 0.8 scattering techniques. Neutron powder diffraction verifies that, in both alloys, the principal type of interstitial absorption site is the quadrilateral base of a Pd-defined pyramid situated on the face of an empty triangular prism.

  1. A CONTINUOUS MIXED SUSPENSION MIXED PRODUCT REMOVAL DISSOLVER

    Microsoft Academic Search

    T. A. MASHINGAIDZE; J. GARSIDE; N. S. TAVARE

    1987-01-01

    A mathematical model for a continuous mixed suspension mixed product removal (MSMPR) dissolver operating with a continuous feed of solid particles has been developed. The model predicts the exit size distribution for a given feed size distribution and operating conditions. In addition the method of s plane analysis has been used to determine dissolution rates from the measured exit size

  2. 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.

  3. Dissolved organic matter and estrogenic potential of landfill leachate

    Microsoft Academic Search

    Fan Lü; Hua Zhang; Cheng-Hsuan Chang; Duu-Jong Lee; Pin-Jing He; Li-Ming Shao; Ay Su

    2008-01-01

    The estrogenic potentials of leachate samples collected at Laogang Sanitary Landfill in Shanghai, China were measured together with the associated dissolved organic matter (DOM) in leachate samples. Over 99% of the DOM in fresh leachate was removed upon 3–7 years of landfill, leaving only DOM with strong fluorescent activity. Anoxic or aerobic treatment of landfill leachate can further degrade DOM

  4. SELF-DEPLETING AMPEROMETRIC SENSOR FOR PPB LEVEL DISSOLVED OXYGEN

    Microsoft Academic Search

    Chang-Dong Feng; Richard A. Payne; Rosemount Analytical

    In order to achieve the ppb level accuracy with an amperometric dissolved oxygen sensor, the reduction of background current is necessary. A sensing model has been developed through the analysis of both sensing and background current. The model reveals that the oxygen flux contributing to the background current can be limited significantly through the introduction of a diffusion path. A

  5. Nature and Transformation of Dissolved Organic Matter in

    E-print Network

    not contributed by internal loading. Introduction Dissolved organic matter (DOM) plays a major role influence on transformations that occur during treatment, (ii) the climate factors have a secondary effect a function of chemical concentrations, envi- ronmental factors, and hydraulic retention time (HRT

  6. 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...

  7. 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...

  8. Fluxes of dissolved organic carbon from California continental margin sediments

    Microsoft Academic Search

    DAVID J. BURDIGE; W ILLIAM M. BERELSON; KENNETH H. COALE; James McManus; KENNETH S. JOHNSON

    1999-01-01

    Fluxes of dissolved organic carbon (DOC) from marine sediments represent a poorly constrained component of the oceanic carbon cycle that may affect the concentration and composition of DOC in the ocean. Here we report the first in situ measurements of DOC fluxes from continental margin sediments (water depths ranging from 95 to 3,700 m), and compare these fluxes with measured

  9. MICRO GASOMETRIC DETERMINATION OF DISSOLVED OXYGEN AND NITROGEN

    Microsoft Academic Search

    P. F. SCHOLANDER; L. VAN DAM; C. LLOYD CLAFF; J. W. KANWISHER

    For polluted water and many biological fluids the Winkler method for the de termination of dissolved oxygen may easily become unreliable, or inapplicable. This difficulty can be avoided by using gasometnic methods. We describe below such a method for the determination of oxygen (and nitrogen) in one cubic centimeter of water. It has been used extensively under field conditions to

  10. Primary production in the Arctic Ocean estimated from dissolved oxygen

    Microsoft Academic Search

    Lawrence R. Pomeroy

    1997-01-01

    The deep, central basins of the Arctic Ocean have been thought to support little biological production. However, summer dissolved oxygen data from the upper mixed layer of the ice-covered central Arctic Ocean yield estimates of primary production which are high enough to account for oxygen utilization in the halocline. Thus, it may not be necessary to postulate either that all

  11. Climate Variability, Dissolved Organic Carbon, UV Exposure, and Amphibian Decline

    Microsoft Academic Search

    P. D. Brooks; C. M. O'Reilly; S. Diamond; S. Corn; E. Muths; K. Tonnessen; D. H. Campbell

    2001-01-01

    Increasing levels of UV radiation represent a potential threat to aquatic organisms in a wide range of environments, yet controls on in situ variability on UV exposure are relatively unknown. The primary control on the penetration of UV radiation in surface water environments is the amount of photoreactive dissolved organic carbon (DOC). Consequently, biogeochemical processes that control the cycling of

  12. S isotope values of dissolved sulfate (SO4

    E-print Network

    Pichler, Thomas

    with sulfuric acid (H2SO4) and lead (Pb), as a result of battery manu- facturing or recycling, is a commond34 S isotope values of dissolved sulfate (SO4 2) ) as a tracer for battery acid (H2SO4 in groundwater provided the information necessary to evaluate the source, transport and fate of battery acid

  13. 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)

  14. 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…

  15. 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...

  16. Assimilable organic carbon (AOC) and biodegradable dissolved organic carbon (BDOC)

    Microsoft Academic Search

    Isabel C Escobar; Andrew A Randall

    2001-01-01

    The objective of this study was to evaluate the necessity of measuring both assimilable organic carbon (AOC) and biodegradable dissolved organic carbon (BDOC) as indicators of bacterial regrowth potential. AOC and BDOC have often been measured separately as indicators of bacterial regrowth, or together as indicators of bacterial regrowth and disinfection by-product formation potential, respectively. However, this study proposes that

  17. Degradation of Dissolved Organic Carbon in Permeable Coastal Sediments

    Microsoft Academic Search

    Lindsay Chipman

    2008-01-01

    This study addresses the decomposition of dissolved organic carbon (DOC) in highly permeable coastal sand sediments. DOC fluxes from shelf sediments (~180 Tg C yr-1) are significant, roughly equal to the DOC flux from rivers (~200 Tg C yr-1) and to the rate of carbon burial in marine sediments (~160 Tg C yr-1) (Burdige et al., 1999). DOC thus plays

  18. ESTIMATING DISSOLVED ORGANIC CARBON PARTITION COEFFICIENTS FOR NONIONIC ORGANIC CHEMICALS

    EPA Science Inventory

    A literature search was performed for dissolved organic carbon/water partition coefficients for nonionic chemicals (Kdoc) and Kdoc data was taken from more than sixty references. The Kdoc data were evaluated as a function of the n-octanol/water partition coefficients (Kow). A pre...

  19. 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…

  20. Isotope fractionation during oxidation of tetravalent uranium by dissolved oxygen

    NASA Astrophysics Data System (ADS)

    Wang, Xiangli; Johnson, Thomas M.; Lundstrom, Craig C.

    2015-02-01

    We conducted laboratory experiments to investigate isotopic fractionations during oxidation of tetravalent uranium, U(IV), by dissolved oxygen. In hydrochloric acid media with the U(IV) dissolved, the ?238U value of the remaining U(IV) increased as the extent of oxidation increased. The ?238U value of the product U(VI) paralleled, but was offset to 1.1 ± 0.2‰ lower than the remaining U(IV). In contrast, oxidation of solid U(IV) by dissolved oxygen in 20 mM NaHCO3 solution at pH = 9.4 caused only a weak fractionation (?0.1‰ to 0.3‰), with ?238U being higher in the dissolved U(VI) relative to the solid U(IV). We suggest that isotope fractionation during oxidation of solid U(IV) is inhibited by a "rind effect", where the surface layer of the solid U(IV) must be completely oxidized before the next layer is exposed to oxidant. The necessity of complete conversion of each layer results in minimal isotopic effect. The weak shift in ?238U of U(VI) is attributed to adsorption of part of the product U(VI) to the solid U(IV) surfaces.

  1. Effectiveness of Various Source Zone and Dissolved Plume Remediation Measures for Sites with Residual DNAPL and DNAPL Pool Sources

    NASA Astrophysics Data System (ADS)

    Christ, J.; Parker, J.

    2007-05-01

    A model is described for transient field-scale DNAPL dissolution kinetics with (i) source zone biodecay, (ii) dissolved phase transport downgradient of the source, and (iii) dissolved plume mass losses due to biodecay and volatilization. The source model considers effects of DNAPL "architecture" on the functional dependence of dissolution kinetics versus source mass depletion, based on results of a high-resolution numerical simulations and field studies by a number of researchers. A formulation is presented that is convenient for model calibration and for uncertainty analyses on forward predictions. The model is employed to evaluate differences in source depletion and dissolved plume attenuation over time for sources dominated by residual DNAPL ("ganglia") or by DNAPL pools or lenses. In addition to the case of natural attenuation, the effectiveness of various source zone and dissolved plume remediation strategies are investigated, including: partial source zone mass removal, partial source zone flow reduction, enhanced source zone biodecay, enhanced source zone mass transfer kinetics, enhanced dissolved plume biodecay, enhanced volatilization, and various combinations of these. For each source type and remediation scenario, source mass flux and concentrations at downgradient receptor locations are evaluated versus time. Times to achieve remediation criteria are compared for each case. Remediation times are generally greater for pool-dominated sources than for residual DNAPL sources under otherwise comparable conditions; however, successful remediation can be achieved even for more intransigent pool-dominated problems by using more aggressive source strategies and/or by combining multiple strategies, especially if compliance points are further downgradient from the source or risk-based cleanup levels can be employed.

  2. A variable reaction rate model for chlorine decay in drinking water due to the reaction with dissolved organic matter.

    PubMed

    Hua, Pei; Vasyukova, Ekaterina; Uhl, Wolfgang

    2015-05-15

    A second order kinetic model for simulating chlorine decay in bulk water due to the reaction with dissolved organic matter (DOM) was developed. It takes into account the decreasing reactivity of dissolved organic matter using a variable reaction rate coefficient (VRRC) which decreases with an increasing conversion. The concentration of reducing species is surrogated by the maximum chlorine demand. Temperature dependency, respectively, is described by the Arrhenius-relationship. The accuracy and adequacy of the proposed model to describe chlorine decay in bulk water were evaluated and shown for very different waters and different conditions such as water mixing or rechlorination by applying statistical tests. It is thus very well suited for application in water quality modeling for distribution systems. PMID:25765169

  3. 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.

  4. 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 = ? (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.

  5. Photochemical Oxidation of Dissolved Elemental Mercury by Carbonate Radicals in Water

    SciTech Connect

    He, Feng [ORNL; Zhao, Wenrong [Zhejiang University; Liang, Liyuan [ORNL; Gu, Baohua [ORNL

    2014-01-01

    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, HCO3-, 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 HCO3- and NO3-, whereas HCO3-, 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.

  6. A three-phase free boundary problem with melting ice and dissolving gas

    E-print Network

    Maurizio Ceseri; John M. Stockie

    2014-11-05

    We develop a mathematical model for a three-phase free boundary problem in one dimension that involves the interactions between gas, water and ice. The dynamics are driven by melting of the ice layer, while the pressurized gas also dissolves within the meltwater. The model incorporates a Stefan condition at the water-ice interface along with Henry's law for dissolution of gas at the gas-water interface. We employ a quasi-steady approximation for the phase temperatures and then derive a series solution for the interface positions. A non-standard feature of the model is an integral free boundary condition that arises from mass conservation owing to changes in gas density at the gas-water interface, which makes the problem non-self-adjoint. We derive a two-scale asymptotic series solution for the dissolved gas concentration, which because of the non-self-adjointness gives rise to a Fourier series expansion in eigenfunctions that do not satisfy the usual orthogonality conditions. Numerical simulations of the original governing equations are used to validate the series approximations.

  7. Greenhouse gases dissolved in soil solution - often ignored, but important?

    NASA Astrophysics Data System (ADS)

    Weymann, Daniel; Brueggemann, Nicolas; Puetz, Thomas; Vereecken, Harry

    2014-05-01

    Flux measurements of climate-relevant trace gases from soils are frequently undertaken in contemporary ecosystem studies and substantially contribute to our understanding of greenhouse gas balances of the biosphere. While the great majority of such investigations builds on closed chamber and eddy covariance measurements, where upward gas fluxes to the atmosphere are measured, fewest concurrently consider greenhouse gas dissolution in the seepage and leaching of dissolved gases via the vadose zone to the groundwater. Here we present annual leaching losses of dissolved N2O and CO2 from arable, grassland, and forest lysimeter soils from three sites differing in altitude and climate. We aim to assess their importance in comparison to direct N2O emission, soil respiration, and further leaching parameters of the C- and N cycle. The lysimeters are part of the Germany-wide lysimeter network initiative TERENO-SoilCan, which investigates feedbacks of climate change to the pedosphere on a long-term scale. Soil water samples were collected weekly from different depths of the profiles by means of suction cups. A laboratory pre-experiment proved that no degassing occurred under those sampling conditions. We applied the headspace equilibration technique to determine dissolved gas concentrations by gas chromatography. The seepage water of all lysimeters was consistently supersaturated with N2O and CO2 compared to water equilibrated ambient air. In terms of N2O, leaching losses increased in the ascending order forest, grassland, and arable soils, respectively. In case of the latter soils, we observed a strong variability of N2O, with dissolved concentrations up to 23 ?g N L-1. However, since seepage discharge of the arable lysimeters was comparatively small and mostly limited to the hydrological winter season, leached N2O appeared to be less important than direct N2O emissions. In terms of dissolved CO2,our measurements revealed considerable leaching losses from the mountainous forest and grassland soils, based on concentrations up to 24 mg C L-1 and high seepage discharge. Such losses turned out to be similarly important like soil respiration, particularly during winter when temperature-dependent soil respiration declined. In conclusion, the results of the first year of our measurements provide evidence that dissolved greenhouse gases should be considered in studies which aim to assess full greenhouse gas balances, particularly in ecosystems where hydrological conditions favour microbial activity and high leaching losses.

  8. 40 CFR 795.70 - Indirect photolysis screening test: Sunlight photolysis in waters containing dissolved humic...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Indirect photolysis screening test: Sunlight photolysis in waters containing dissolved... Indirect photolysis screening test: Sunlight photolysis in waters containing dissolved...case, the chemical of interest absorbs sunlight directly and is transformed to...

  9. 40 CFR 795.70 - Indirect photolysis screening test: Sunlight photolysis in waters containing dissolved humic...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Indirect photolysis screening test: Sunlight photolysis in waters containing dissolved... Indirect photolysis screening test: Sunlight photolysis in waters containing dissolved...case, the chemical of interest absorbs sunlight directly and is transformed to...

  10. 75 FR 13556 - Impact of Dissolvable Tobacco Use on Public Health; Request for Comments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-22

    ...of Dissolvable Tobacco Use on Public Health; Request for Comments AGENCY...dissolvable tobacco products may impact public health, including such use among children...and can be easily concealed, public health officials have raised...

  11. A procedure for measuring the metrological performance of a dissolved oxygen sensor

    Microsoft Academic Search

    A. K. Rodionov

    2009-01-01

    A procedure for measuring the linearity of a dissolved oxygen sensor is proposed and substantiated mathematically. The application of the proposed procedure is illustrated by the results from an experimental study of a serially produced analyzer of dissolved oxygen.

  12. Inuence of dissolved organic matter source on lake bacterioplankton structure and function ^ implicationsfor seasonal

    E-print Network

    Notre Dame, University of

    , nutrients, and pH). Seasonal changes correlated with temperature, chlorophyll and dissolved organic carbon to the relative loading of autochthonous and allochthonous carbon (water colour, dissolved organic carbon

  13. 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...

  14. 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.

  15. Biodegradable Materials and Their Effect on Dissolved Oxygen Levels

    NSDL National Science Digital Library

    In this laboratory exercise, students will design and conduct an experiment to evaluate the effect of the presence of biodegradable materials on dissolved oxygen levels. They will come to understand the effect of biodegradable pollutants on water quality, design and conduct an experiment, interpret data, suggest additional studies, and preform serial dilutions. The students will discover that in aquatic systems, aerobic microorganisms will consume biodegradable material for energy, and in doing so will also take up oxygen from the environment as part of the cellular respiration process. They will also learn that scientists use dissolved oxygen levels as an indication of contamination by such pollutants as sewage, agricultural runoff, and organic industrial effluents. This activity has an accompanying teacher site with hints and more information. There are also links to several related sites.

  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. Radiocarbon in dissolved organic carbon of the South Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Druffel, E. R. M.; Griffin, S.

    2015-05-01

    Marine dissolved organic carbon (DOC) originates mainly from primary production using dissolved inorganic carbon (DIC) that has young 14C ages. Paradoxically, the 14C age of deep DOC ranges from 4000 to 6400 14C years, indicating that a portion of DOC survives multiple, deep ocean mixing cycles. Here we show that 14C ages of DOC from the deep South Pacific are equal to those from the deep north central Pacific. This is contrary to DIC 14C ages that increase from south to north in the deep Pacific. We hypothesize that DOC in the South Pacific is influenced by input of ancient DOC from hydrothermal flanks and ridges of the East Pacific Rise. We show that DOC ?14C values in the deep Pacific are not controlled by aging during northward transport of deep waters, indicating that the deep oceanic carbon cycle needs reassessment.

  18. Avian Digestive Tract Simulation To Study the Effect of Grit

    E-print Network

    Green, Andy J.

    wheat seed). Dissolved Pb levels in simulated gizzards were consistently higher in the presence supplementation with clean grit may promote reduced shot ingestion in susceptible species. The amount of grit

  19. The measurement of dissolved organic and particulate carbon in seawater

    Microsoft Academic Search

    DAVID W. MENZEL; RALPH F. VACCARO

    1964-01-01

    A method is dcscribcd for the rapid dctcrmination of dissolved organic carbon in seawater in concentrations bctwcen 0.1 and 20 mg\\/liter. The oxidation is carried out in sealed glass ampoules using K&Lox as an oxidizing agent after the sample has been freed of inorganic carbon. The resulting CO2 is passed through a nondispcrsive infrared analyzer using nitro- gen as a

  20. Seasonal dynamics of colored dissolved material in the Sargasso Sea

    Microsoft Academic Search

    N. B. Nelson; D. A. Siegel; A. F. Michaels

    1998-01-01

    Observations from the Sargasso Sea have shown that the light attenuation spectrum is a function of both phytoplankton pigments and a detrital-like component that varies independently. Here we examine the nature and dynamics of these detrital-like variations by analyzing a time-depth series of visible and ultraviolet light absorption spectra for colored (chromophoric) dissolved materials [CDOM; ag(?)] and detrital particulates [ad(?)

  1. A hand-held optical sensor for dissolved oxygen measurement

    Microsoft Academic Search

    Dan Xiao; Yuanyao Mo; Martin M. F. Choi

    2003-01-01

    A hand-held dissolved oxygen optical sensor based on solid-state electronics and highly oxygen-sensitive luminescence material has been developed. Oxygen-sensitive dye absorbed on silica gel particles was dispersed in a 0.2 mm homogenous silicone rubber film (optode membrane) and coated on a 580 nm long-pass filter. The O2-sensitive dye was excited by an ultra-bright blue light-emitting diode and the emission intensity

  2. A flow system for calibration of dissolved oxygen sensors

    Microsoft Academic Search

    P. Jeroschewski; D. zur Linden

    1997-01-01

    Well-defined oxygen standard solutions were obtained by the electrolysis of water in a coulometric oxygen generator. The\\u000a generator was integrated into a flow system that includes the degassing of the carrier electrolyte, the generation of dissolved\\u000a oxygen and the temperature control of the carrier electrolyte. The current efficiency of oxygen generation was found to be\\u000a 100% by the Winkler titration

  3. ORMOSIL oxygen sensors on polystyrene microplate for dissolved oxygen measurement

    Microsoft Academic Search

    Hei-Leung Pang; Nga-Yan Kwok; Larry Ming-Cheung Chow; Chi-Hung Yeung; Kwok-Yin Wong; Xi Chen; Xiaoru Wang

    2007-01-01

    Oxygen sensors prepared from tetramethyl orthosilicate and dimethoxy dimethylsilane with tris(4,7-diphenyl-1,10-phenanthroline)ruthenium (II) as the sensing dye were coated onto the well bottom surface of a 96-well polystyrene microtiter plate to give a high-throughput system for dissolved oxygen measurement. The oxygen sensors give linear Stern–Volmer calibration plots, and produce reliable and reproducible results in the determination of IC50 values of drugs

  4. Fluorescent dissolved organic matter in marine sediment pore waters

    Microsoft Academic Search

    David J. Burdige; Scott W. Kline; Wenhao Chen

    2004-01-01

    Fluorescent dissolved organic matter (FDOM) in sediment pore waters from contrasting sites in the Chesapeake Bay and along the mid-Atlantic shelf\\/slope break was studied using three-dimensional fluorescence spectroscopy. Benthic fluxes of FDOM were also examined at the Chesapeake Bay sites. The major fluorescence peaks observed in these pore waters corresponded to those observed in the water column. These included peaks

  5. Synchronous variation of dissolved organic carbon and color in lakes

    Microsoft Academic Search

    Michael L. Pace; Jonathan J. Cole

    2002-01-01

    Temporal variation in dissolved organic carbon (DOC) and water color (light absorption at 440 nm) was measured in 20 lakes in northern Michigan that varied in DOC, pH, morphometry, and relative productivity as indicated by chlorophyll and total phosphorus (TP). Monthly observations during May-August over 6 yr revealed that DOC and color varied by 6- and 28-fold among lakes and

  6. The behavior of dissolved inorganic selenium in the Bohai Sea

    Microsoft Academic Search

    Qing-Zheng Yao; Jing Zhang

    2005-01-01

    Two cruises of “R\\/V Dong Fang Hong 2” were carried out in September 1998 and May 1999, respectively, to understand the behavior of selenium in the Bohai Sea. Selenium species (dissolved inorganic selenium, selenite) are determined by HG-AFS for 30 grid stations. Selenium concentrations display short-term variability and seasonal change in the Bohai Sea, with higher levels in shallow coastal

  7. 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.

  8. Hydrography of chromophoric dissolved organic matter in the North Atlantic

    Microsoft Academic Search

    Norman B. Nelson; David A. Siegel; Craig. A. Carlson; Chantal Swan; William M. Smethie; Samar Khatiwala

    2007-01-01

    The distribution and optical absorption characteristics of chromophoric dissolved organic matter (CDOM) were systematically investigated along three meridional transects in the North Atlantic Ocean and Caribbean Sea conducted as part of the 2003 US CLIVAR\\/CO2 Repeat Hydrography survey. Hydrographic transects covered in aggregate a latitudinal range of 5° to 62° north along longitudes 20°W (line A16N, Leg 1), 52°W (A20),

  9. Benthic bacterial biomass supported by streamwater dissolved organic matter

    Microsoft Academic Search

    Thomas L. Bott; Louis A. Kaplan; Frank T. Kuserk

    1984-01-01

    Bacterial biomass in surface sediments of a headwater stream was measured as a function of dissolved organic carbon (DOC) flux and temperature. Bacterial biomass was estimated using epifluorescence microscopic counts (EMC) and ATP determinations during exposure to streamwater containing 1,788?g DOC\\/liter and after transfer to groundwater containing 693?g DOC\\/liter. Numbers of bacteria and ATP concentrations averaged 1.36×109 cells and 1,064

  10. 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.

  11. Sensors and instruments for oceanic dissolved carbon measurements

    NASA Astrophysics Data System (ADS)

    Schuster, U.; Hannides, A.; Mintrop, L.; Körtzinger, A.

    2009-11-01

    Highly accurate and precise measurements of marine carbon components are required in the study of the marine carbon cycle, particularly when investigating the causes for its variability from seasonal to interannual timescales. This is especially true in the investigation of the consequences of anthropogenic influences. The analysis of any marine carbon component requires elaborate instrumentation, most of which is currently used onboard ships, either in manual or automated mode. Technological developments result in more and more instruments that have sufficient long-term reliability so that they can be deployed on commercial ships, surface moorings, and buoys, whilst the great technological and operational challenges mean that only few sensors have been developed that can be used for sub-surface in situ measurements on floats, robots, or gliders. There is a special need for autonomous instruments and sensors that are able to measure a combination of different components, in order to increase the spatial and temporal coverage of marine carbon data. This paper describes analytical techniques used for the measurement of the marine dissolved carbon components, both inorganic and organic: the fugacity of CO2, total dissolved inorganic carbon, pH, alkalinity, and dissolved organic carbon. By pointing out advantages, disadvantages, and/or challenges of the techniques employed in the analysis of each component, we aim to aid non-carbon marine scientists, sensor developers and technologists, in the decision of which challenges to address in further development.

  12. Sensors and instruments for oceanic dissolved carbon measurements

    NASA Astrophysics Data System (ADS)

    Schuster, U.; Hannides, A.; Mintrop, L.; Körtzinger, A.

    2009-02-01

    Highly accurate and precise measurements of marine carbon components are required in the study of the marine carbon cycle, particularly when investigating the causes for its variability from seasonal to interannual timescales. This is especially true in the investigation of the consequences of anthropogenic influences. The analysis of any component requires elaborate instrumentation, most of which is currently used onboard ships, either in manual mode or autonomous mode. Technological developments result in more and more instruments that have long-term reliability so that they can be deployed on surface moorings and buoys, whilst the great technological and operational challenges mean that only few sensors have been developed that can be used for sub-surface in situ measurements on floats, robots, or gliders. There is a special need for autonomous instruments and sensors that are able to measure a combination of different components, in order to increase the spatial and temporal coverage of marine carbon data. This paper describes analytical techniques used for the detection of the marine dissolved carbon components, both inorganic and organic: the fugacity of CO2, total dissolved inorganic carbon, pH, alkalinity, and dissolved organic carbon. By pointing out advantages, disadvantages, and challenges of the techniques employed in the analysis of each component, we aim to aid non-carbon marine scientists, sensor developers and technologists, in the decision where to tackle the challenges of further development.

  13. Sequestration of Dissolved CO2 in the Oriskany Formation

    SciTech Connect

    Dilmore, R.M.; Allen, D.E. (Salem State College, Salem, MA); 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.

  14. Dissolved carbon leaching from soil is a crucial component of the net ecosystem carbon balance

    Microsoft Academic Search

    R. Kindler; J. Siemens; K. Kaiser; E. J. Moors

    2011-01-01

    Estimates of carbon leaching losses from different land use systems are few and their contribution to the net ecosystem carbon balance is uncertain. We investigated leaching of dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), and dissolved methane (CH4), at forests, grasslands, and croplands across Europe. Biogenic contributions to DIC were estimated by means of its ?13C signature. Leaching of

  15. Erythrosin B encapsulated in a fluoropolymer matrix for dissolved oxygen optical sensing in aggressive aqueous environments

    Microsoft Academic Search

    R. N Gillanders; M. C Tedford; P. J Crilly; R. T Bailey

    2004-01-01

    A robust thin film dissolved oxygen sensor was fabricated by trapping erythrosin B in a flexible fluoropolymer matrix. Strong phosphorescence, which was partially quenched by dissolved oxygen, was observed when the sensor was immersed in water. Residual phosphorescence, which was not quenched by dissolved oxygen, was attributed to the presence of aggregated dye species. The sensor was optically transparent, resistant

  16. Thin film dissolved oxygen sensor based on platinum octaethylporphyrin encapsulated in an elastic fluorinated polymer

    Microsoft Academic Search

    R. N. Gillanders; M. C. Tedford; P. J. Crilly; R. T. Bailey

    2004-01-01

    A robust thin film dissolved oxygen sensor was fabricated by encapsulating platinum octaethylporphyrin (PtOEP) in an oxygen permeable elastic fluorinated co-polymer matrix. Phosphorescence, which was partially quenched by dissolved oxygen, was observed when the sensor was immersed in water. Aggregation of the dye was observed at elevated temperatures. Dye aggregate phosphorescence was not or only partially quenched by dissolved oxygen.

  17. Dissolved Oxygen Monitoring and Control System based on the CDMA platform

    Microsoft Academic Search

    Shuhua Ma; Jinkuan Wang; Yiding Zhao

    2010-01-01

    In aquiculture, the dissolved oxygen concentration in the water has great influence on the growth and development of fish. It is quite necessary to monitor the dissolved oxygen concentration in the fish pond. In this paper Dissolved Oxygen Monitoring and Control System is designed, which we present the system structure chart, circuit for communication, and the list of some program

  18. MEMS Needle-type Sensor Array for in Situ Measurements of Dissolved

    E-print Network

    Papautsky, Ian

    MEMS Needle-type Sensor Array for in Situ Measurements of Dissolved Oxygen and Redox Potential J I of dissolved oxygen (DO) and oxidation reduction potential (ORP) fabricated using microelectrome- chanical used to analyze redox potential, dissolved oxygen (DO), and pH in environmental samples

  19. Effects of dissolved gas content on pool boiling of a highly wetting fluid

    Microsoft Academic Search

    S. M. You; Y. S. Hong; T. W. Simon; A. Bar-Cohen

    1995-01-01

    Experimental results on pool boiling heat transfer from a horizontal cylinder in an electronic cooling fluid (FC-72) are presented. The effects on the boiling curve of having air dissolved in the fluid are documented, showing that fluid in the vicinity of the heating element is apparently liberated of dissolved gas during boiling. Dissolved gas was found to influence boiling incipience

  20. pH change induces shifts in the size and light absorption of dissolved organic matter

    E-print Network

    Pace, Michael L.

    pH change induces shifts in the size and light absorption of dissolved organic matter Michael L of photobleaching, molar absorp- tion (i.e. light absorbance at 440 nm/dissolved organic carbon concentration) wouldH and chemical composition of inland waters. Keywords Dissolved organic matter Á Light absorption Á pH Á Lakes Á

  1. Differences in Dissolved Cadmium and Zinc Uptake among Stream Insects: Mechanistic Explanations

    Microsoft Academic Search

    DAVID B. B UCHWALTER

    This study examined the extent to which dissolved Cd and Zn uptake rates vary in several aquatic insect taxa commonly used as indicators of ecological health. We further attempted to explain the mechanisms underlying observed differences. By comparing dissolved Cd and Zn uptake rates in several aquatic insect species, we demonstrated that species vary widely in these processes. Dissolved uptake

  2. 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 relative size of the transient storage zone and how it changes in the downstream direction, as well as the nature of hydrologic variability.

  3. 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.

    2014-01-01

    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

  4. Relationships between colored dissolved organic matter and dissolved organic carbon in different coastal gradients of the Baltic Sea.

    PubMed

    Harvey, E Therese; Kratzer, Susanne; Andersson, Agneta

    2015-06-01

    Due to high terrestrial runoff, the Baltic Sea is rich in dissolved organic carbon (DOC), the light-absorbing fraction of which is referred to as colored dissolved organic matter (CDOM). Inputs of DOC and CDOM are predicted to increase with climate change, affecting coastal ecosystems. We found that the relationships between DOC, CDOM, salinity, and Secchi depth all differed between the two coastal areas studied; the W Gulf of Bothnia with high terrestrial input and the NW Baltic Proper with relatively little terrestrial input. The CDOM:DOC ratio was higher in the Gulf of Bothnia, where CDOM had a greater influence on the Secchi depth, which is used as an indicator of eutrophication and hence important for Baltic Sea management. Based on the results of this study, we recommend regular CDOM measurements in monitoring programmes, to increase the value of concurrent Secchi depth measurements. PMID:26022322

  5. 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 biogenic particles and of Se(o) only to the tetravalent species is the cause for the lower ratio of SeVI/Se(T) in the lake.

  6. Modelling the Distributions of Dissolved Zn and Ni in the Tamar Estuary Using Hydrodynamics Coupled with Chemical Kinetics

    NASA Astrophysics Data System (ADS)

    Liu, Y. P.; Millward, G. E.; Harris, J. R. W.

    1998-11-01

    Suspended particulate matter (SPM) from the Tamar Estuary was separated into permanent SPM (PSPM) and temporary SPM (TSPM) by settling experiments. Both particulate fractions were chemically characterized and used to study the kinetics of adsorption and desorption of Zn and Ni. The results showed that the adsorption of Zn and Ni at salinity=0 was biphasic, with an initial rapid step, completed in <5 min, followed by a slower progression to equilibrium. The PSPM adsorbed relatively more Zn and Ni than the TSPM, which had a smaller specific surface area and lower acetic acid-leachable Fe and Mn content. Labile Zn and Ni desorbed biphasically, when the metal-laden particles were suspended in seawater (salinity=30) and a greater amount of metal was desorbed from TSPM than PSPM. The sorption mechanisms were described by reversible, first order reactions, from which reaction constants were estimated for the slow step. The response time for the adsorption of dissolved Zn during the slow step (i.e. time to achieve 63% of the new equilibrium) was 3-5 h, whereas during desorption of Zn it was approximately 25 h. For dissolved Ni, the response time for the slow step was about 13 h and in the range 33-50 h for the desorption reaction. Sorption reaction constants for Zn and Ni were incorporated into the estuarine contaminant simulator (ECoS) and used to predict dissolved Zn and Ni distributions in the Tamar Estuary. The predicted trends in dissolved metal concentrations were in general agreement with published field observations.

  7. Hydrological Variables and Dissolved Phosphorus in the Runoff from No-tilled Soil after Application of Swine Liquid

    NASA Astrophysics Data System (ADS)

    Barbosa, F. T.; Bertol, I.; de Amaral, A. J.; Grahl dos Santos, P.; Ramos, R. R.; Werner, R. S.; Miras Avalos, J. M.

    2012-04-01

    Swine manure is used as a soil fertilizer in South Brazil. Commonly, it is applied continuously and in great amounts over surfaces with an important relief and without facilities that avoid water erosion. Thus, this manure is a potential risk of environmental pollution, mainly for the eutrophication of water bodies due to a runoff rich in nutrients. The aim of this work was to assess some soil hydrological parameters and to quantify the dissolved phosphorus losses in the runoff from no-tilled soils after the application of swine liquid manure. The experiment was carried out in the Highlands of Santa Catarina State, Brazil, in June 2009, over a Nitisol. On field plots, a 90-minute simulated rainfall test was performed with a rotating boom rainfall simulator and rainfall intensity of 70 mm h-1. Prior to the rainfall simulation, sowing was performed using a disk planter either with or without tines. Spacing between lines was 0.5 m. Swine liquid manure was applied at rates of 0.0, 30 and 60 m3ha-1 to the plots planted using tines; whereas it was applied at 15, 45 e 75 m3ha-1 to the plots were no tines were used for planting. During rainfall simulation, readings of runoff rate were taken each five minutes; total water loss was calculated by integrating all the 5-minute readings. Runoff samples were collected at 10 minutes intervals, and they were filtered through a 0.45 ?m filter to determine dissolved phosphorus. Hydrological variables were significantly affected by the use of tines, which favoured infiltration and reduced runoff as compared to the non-use of tines. Runoff started at 28 and 11 minutes, water losses were 252 and 467 m3 ha-1, maximum runoff rate were 29 and 42 mm h-1 and constant rates of infiltration were 41 and 28 mm h-1, for treatments with and without tines, respectively. Dissolved phosphorus increased with the rate of swine liquid manure applied, with a trend to decrease from the beginning to the end of rainfall. The highest concentration was 0.19 mg L-1 and 0.85 mg L-1, for treatments with and without tines, respectively. Dissolved phosphorus losses (g ha-1) increased linearly with swine liquid manure (m3 ha-1). The angular coefficient of the equation, which relates the increase in phosphorus loss with the applied manure, was lower when using tines, indicating that their use may reduce eutrophication risks from areas where swine manure is used. Equations for phosphorus losses were y = 4.3 + 0.5x and y = 28.1 + 1.9x, for treatments with and without tines, respectively.

  8. Process for coal liquefaction by separation of entrained gases from slurry exiting staged dissolvers

    DOEpatents

    Givens, Edwin N. (Bethlehem, PA); Ying, David H. S. (Macungie, PA)

    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.

  9. Optical Characterization of Dissolved Organic Matter in Maine Rivers

    NASA Astrophysics Data System (ADS)

    White, D. P.; Roesler, C. S.; Bourakovsky, A.; Drapeau, S.; Huntington, T. G.; Billmire, M.; Camill, P.

    2014-12-01

    The coastal waters of the Gulf of Maine are significantly impacted by the input of fresh water from a distributed river system. In this study, we focus on the four largest watersheds (Androscoggin, Kennebec, Penobscot and St. John) that contribute to the freshwater inputs. In particular, we investigated the input of dissolved organic carbon via PARAFAC analysis of excitation/emission matrix fluorescence spectroscopy. Monthly sampling of over 65 stations for three years has yielded a wealth of information about tributary characteristics. Specifically, we investigated the role of water quality properties and landscape coverage in the mobilization and flux of different components of DOC and how those properties vary spatially across the landscape and temporally over seasons and between years. Across all rivers, humic-like materials were the most prevalent components at the river mouths; accumulating along the rivers due to sequential tributary inputs. The concentration of humic-like materials increased latitudinally from the Androscoggin to St John, a geographic progression in source material also correlated to climate variations, land coverage or bedrock acidity. Dissolved proteins displayed positive relationships with climatological Chlorophyll a and total Nitrogen values. In all rivers, peak fluorescence of dissolved proteins was observed during summer months, with the maximum intensity observed in the Androscoggin River. The magnitude and pattern of seasonal flux of fluorescent materials into the Gulf of Maine was very similar between the Penobscot and the Kennebec rivers. The flux of all DOM components was highest during the spring freshet, with a secondary peak during fall precipitation maxima and lowest during August, likely due to both low mobilization and photo degradation of river borne materials.

  10. Sources of dissolved salts in the central Murray Basin, Australia

    USGS Publications Warehouse

    Jones, B.F.; Hanor, J.S.; Evans, W.R.

    1994-01-01

    Large areas of the Australian continent contain scattered saline lakes underlain by shallow saline groundwaters of regional extent and debated origin. The normative salt composition of subsurface pore fluids extracted by squeezing cores collected during deep drilling at Piangil West 2 in the central Murray Basin in southeastern Australia, and of surface and shallow subsurface brines produced by subaerial evaporation in the nearby Lake Tyrrell systems, helps constrain interpretation of the origin of dissolved solutes in the groundwaters of this part of the continent. Although regional sedimentation in the Murray Basin has been dominantly continental except for a marine transgression in Oligocene-Pliocene time, most of the solutes in saline surface and subsurface waters in the central Murray Basin have a distinctly marine character. Some of the Tyrrell waters, to the southwest of Piangil West 2, show the increase in NaCl and decrease in sulfate salts expected with evaporative concentration and gypsum precipitation in an ephemeral saline lake or playa environment. The salt norms for most of the subsurface saline waters at Piangil West 2 are compatible with the dilution of variably fractionated marine bitterns slightly depleted in sodium salts, similar to the more evolved brines at Lake Tyrrell, which have recharged downward after evaporation at the surface and then dissolved a variable amount of gypsum at depth. Apparently over the last 0.5 Ma significant quantities of marine salt have been blown into the Murray Basin as aerosols which have subsequently been leached into shallow regional groundwater systems basin-wide, and have been transported laterally into areas of large evaporative loss in the central part of the basin. This origin for the solutes helps explain why the isotopic compositions of most of the subsurface saline waters at Piangil West 2 have a strong meteoric signature, whereas the dissolved salts in these waters appear similar to a marine assemblage. ?? 1994.

  11. Formulation and evaluation of aceclofenac mouth-dissolving tablet.

    PubMed

    Solanki, Shailendra Singh; Dahima, Rashmi

    2011-04-01

    Aceclofenac has been shown to have potent analgesic and anti-inflammatory activities similar to indomethacin and diclofenac, and due to its preferential Cox-2 blockade, it has a better safety than conventional Non steroidal anti-inflammatory drug (NSAIDs) with respect to adverse effect on gastrointestinal and cardiovascular systems. Aceclofenac is superior from other NSAIDs as it has selectivity for Cox-2, a beneficial Cox inhibitor is well tolerated, has better Gastrointestinal (GI) tolerability and improved cardiovascular safety when compared with other selective Cox-2 inhibitor. To provide the patient with the most convenient mode of administration, there is need to develop a fast-disintegrating dosage form, particularly one that disintegrates and dissolves/disperses in saliva and can be administered without water, anywhere, any time. Such tablets are also called as "melt in mouth tablet." Direct compression, freeze drying, sublimation, spray drying, tablet molding, disintegrant addition, and use of sugar-based excipients are technologies available for mouth-dissolving tablet. Mouth-dissolving tablets of aceclofenac were prepared with two different techniques, wet granulation and direct compression, in which different formulations were prepared with varying concentration of excipients. These tablets were evaluated for their friability, hardness, wetting time, and disintegration time; the drug release profile was studied in buffer Phosphate buffered Saline (PBS) pH 7.4. Direct compression batch C3 gave far better dissolution than the wet granulation Batch F2, which released only 75.37% drug, and C3, which released 89.69% drug in 90 minutes. PMID:22171305

  12. Formulation and evaluation of aceclofenac mouth-dissolving tablet

    PubMed Central

    Solanki, Shailendra Singh; Dahima, Rashmi

    2011-01-01

    Aceclofenac has been shown to have potent analgesic and anti-inflammatory activities similar to indomethacin and diclofenac, and due to its preferential Cox-2 blockade, it has a better safety than conventional Non steroidal anti-inflammatory drug (NSAIDs) with respect to adverse effect on gastrointestinal and cardiovascular systems. Aceclofenac is superior from other NSAIDs as it has selectivity for Cox-2, a beneficial Cox inhibitor is well tolerated, has better Gastrointestinal (GI) tolerability and improved cardiovascular safety when compared with other selective Cox-2 inhibitor. To provide the patient with the most convenient mode of administration, there is need to develop a fast-disintegrating dosage form, particularly one that disintegrates and dissolves/disperses in saliva and can be administered without water, anywhere, any time. Such tablets are also called as “melt in mouth tablet.” Direct compression, freeze drying, sublimation, spray drying, tablet molding, disintegrant addition, and use of sugar-based excipients are technologies available for mouth-dissolving tablet. Mouth-dissolving tablets of aceclofenac were prepared with two different techniques, wet granulation and direct compression, in which different formulations were prepared with varying concentration of excipients. These tablets were evaluated for their friability, hardness, wetting time, and disintegration time; the drug release profile was studied in buffer Phosphate buffered Saline (PBS) pH 7.4. Direct compression batch C3 gave far better dissolution than the wet granulation Batch F2, which released only 75.37% drug, and C3, which released 89.69% drug in 90 minutes. PMID:22171305

  13. Chromophoric Dissolved Organic Matter in Southwestern Greenland Lakes

    NASA Astrophysics Data System (ADS)

    Osburn, C. L.; Giles, M. E.; Underwood, G. J. C.

    2014-12-01

    Dissolved organic matter (DOM) is an important property of Arctic lake ecosystems, originating from allochthonous inputs from catchments and autochthonous production by plankton in the water column. Little is known about the quality of DOM in Arctic lakes that lack substantial inputs from catchments and such lakes are abundant in southwestern Greenland. Colored dissolved organic matter (CDOM), the fraction that absorbs ultraviolet (UV) and visible light, is the controlling factor for the optical properties of many surface waters and as well informs on the quality of DOM. We examined the quality of CDOM in 21 lakes in southwestern Greenland, from the ice sheet to the coast, as part of a larger study examining the role of DOM in regulating microbial communities in these lakes. DOM was size fractioned and absorbance and fluorescence was measured on each size fraction, as well as on bulk DOM. The specific ultraviolet absorbance (SUVA) at 254 nm (SUVA254), computed by normalizing absorption (a254) to dissolved organic carbon (DOC) concentration, provided an estimate of the aromatic carbon content of DOM. SUVA values were generally <2, indicating low aromatic content. Parallel factor analysis (PARAFAC) of CDOM fluorescence was used to determine the relative abundance of allochthonous and autochthonous DOM in all size fractions. Younger lakes near the ice sheet and lakes near the coast had lower amounts of CDOM and appeared more microbial in quality. However, lakes centrally located between the ice sheet and the coast had the highest CDOM concentrations and exhibited strong humic fluorescence. Overall distinct differences in CDOM quality were observed between lake locations and among DOM size fractions.

  14. Carbon Cycle - CDOM Activity: Chromophoric Dissolved Organic Matter (CDOM)

    NSDL National Science Digital Library

    In this laboratory activity, students investigate chromophoric dissolved organic matter (CDOM) through gradual dilution of black, green and chamomile tea. Through this activity, students discover how CDOM can dominate the absorption of sunlight, how sunlight degrades CDOM through photochemical oxidation, and how CDOM levels are related to nutrient status, stratification and mixing of the ocean. Materials needed include coffee mugs, hot water, spoons, and tea. This resource is found in Rising Tides, a journal created for teachers and students reporting on current oceanography research conducted by NASA, NOAA, and university scientists, featuring articles, classroom activities, readings, teacher/student questions, and imagery for student investigation of marine science.

  15. 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.

  16. 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...

  17. Relationship between the optical properties of chromophoric dissolved organic matter and total concentration of dissolved organic carbon in the southern Baltic Sea region

    Microsoft Academic Search

    Giovanni M. Ferrari; Mark D. Dowell; Stefania Grossi; Cristina Targa

    1996-01-01

    Absorption and fluorescence of chromophoric dissolved organic matter (CDOM) and dissolved organic carbon (DOC) measurements were performed during three oceanographic surveys in 1994 in the southern Baltic Sea (Polish area of the Baltic Proper). DOC was measured both by high-temperature catalytic oxidation (HTCO) and low-temperature oxidation (LTO) conventional persulphate methods. CDOM fluorescence was shown to be highly correlated with absorption,

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. Cracking of duplex stainless steel due to dissolved hydrogen

    SciTech Connect

    Huang, J.H. [National Tsing Hua Univ., Hsinchu (Taiwan, Province of China). Dept. of Nuclear Engineering; Altstetter, C.J. [Univ. of Illinois, Urbana, IL (United States). Dept. of Materials Science and Engineering

    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).

  3. Carbon isotopic characterisation of dissolved organic matter during water treatment.

    PubMed

    Bridgeman, John; Gulliver, Pauline; Roe, Jessie; Baker, Andy

    2014-01-01

    Water treatment is a series of physio-chemical processes to aid organic matter (OM) removal, which helps to minimise the formation of potentially carcinogenic disinfection by-products and microbial regrowth. Changes in OM character through the treatment processes can provide insight into the treatment efficiency, but radiogenic isotopic characterisation techniques have yet to be applied. Here, we show for the first time that analysis of (13)C and (14)C of dissolved organic carbon (DOC) effectively characterises dissolved OM through a water treatment works. At the sites investigated: post-clarification, DOC becomes isotopically lighter, due to an increased proportion of relatively hydrophilic DOC. Filtration adds 'old' (14)C-DOC from abrasion of the filter media, whilst the use of activated carbon adds 'young' (14)C-DOC, most likely from the presence of biofilms. Overall, carbon isotopes provide clear evidence for the first time that new sources of organic carbon are added within the treatment processes, and that treated water is isotopically lighter and typically younger in (14)C-DOC age than untreated water. We anticipate our findings will precipitate real-time monitoring of treatment performance using stable carbon isotopes, with associated improvements in energy and carbon footprint (e.g. isotopic analysis used as triggers for filter washing and activated carbon regeneration) and public health benefits resulting from improved carbon removal. PMID:24075722

  4. Production of Dissolved Organic Matter During Fungal Wood Rot Decay

    NASA Astrophysics Data System (ADS)

    Filley, T. R.; Jellison, J.; Goodell, B.; Kelley, S.; Davis, M.

    2002-12-01

    Dissolved organic matter mediates numerous biogeochemical processes in soil systems impacting subsurface microbial activity, redox chemistry, soil structure, and carbon and nitrogen sequestration. The structure and chemistry of DOM is a function of the inherited chemistry of the source material, the type of microbial action that has occurred, and selective interaction with mineral substrates. The type of fungal decomposition imparted to woody tissue is a major factor in determining the nature of DOM in forest soils. In order to investigate the relationship between fungal decomposition and the nature of DOM in coniferous forest soils we conducted 32-week inoculation studies on spruce sapwood with basidiomycete brown-rot wood decay fungi where leachable dissolved and colloidal organic matter was separated from decayed residue. A detailed examination of the organic fractions was conducted using 13C-labeled tetramethylammonium hydroxide thermochemolysis, solid-state 13C-NMR, and electrospray mass spectrometry. The progressive stages of microbial decay (cellulolytic and ligninolytic) were manifested in the chemical composition of the DOM which showed an evolution from a composition initially polysaccharide rich to one dominated by mildly oxidized and demethylated lignin. Upon removal of all polysaccharides at 16 weeks the DOM (up to 10% by weight of the original tissue) looked chemically distinct from the degraded residue

  5. 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.

  6. 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-?m 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

  7. 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.

  8. Dissolved organic nitrogen in precipitation: Collection, analysis and atmospheric flux

    SciTech Connect

    Scudlark, J.R.; Church, T.M. [Univ. of Delaware, Lewes, DE (United States). Graduate Coll. of Marine Studies; Russell, K.M. [Univ. of Virginia, Charlottesville, VA (United States). Dept. of Environmental Sciences; [Univ. of Delaware, Lewes, DE (United States). Graduate Coll. of Marine Studies; Montag, J.A.; Maben, J.R.; Keene, W.C.; Galloway, J.N. [Univ. of Virginia, Charlottesville, VA (United States). Dept. of Environmental Sciences

    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.

  9. Biologically labile photoproducts from riverine non-labile dissolved organic carbon in the coastal waters

    NASA Astrophysics Data System (ADS)

    Kasurinen, V.; Aarnos, H.; Vähätalo, A.

    2015-06-01

    In order to assess the production of biologically labile photoproducts (BLPs) from non-labile riverine dissolved organic carbon (DOC), we collected water samples from ten major rivers, removed labile DOC and mixed the residual non-labile DOC with artificial seawater for microbial and photochemical experiments. Bacteria grew on non-labile DOC with a growth efficiency of 11.5% (mean; range from 3.6 to 15.3%). Simulated solar radiation transformed a part of non-labile DOC into BLPs, which stimulated bacterial respiration and production, but did not change bacterial growth efficiency (BGE) compared to the non-irradiated dark controls. In the irradiated water samples, the amount of BLPs stimulating bacterial production depended on the photochemical bleaching of chromophoric dissolved organic matter (CDOM). The apparent quantum yields for BLPs supporting bacterial production ranged from 9.5 to 76 (mean 39) (?mol C mol photons-1) at 330 nm. The corresponding values for BLPs supporting bacterial respiration ranged from 57 to 1204 (mean 320) (?mol C mol photons-1). According to the calculations based on spectral apparent quantum yields and local solar radiation, the annual production of BLPs ranged from 21 (St. Lawrence) to 584 (Yangtze) mmol C m-2 yr-1 in the plumes of the examined rivers. Complete photobleaching of riverine CDOM in the coastal ocean was estimated to produce 10.7 Mt C BLPs yr-1 from the rivers examined in this study and globally 38 Mt yr-1 (15% of riverine DOC flux from all rivers), which support 4.1 Mt yr-1 of bacterial production and 33.9 Mt yr-1 bacterial respiration.

  10. Distribution and photoreactivity of chromophoric dissolved organic matter in northern Gulf of Mexico shelf waters

    NASA Astrophysics Data System (ADS)

    Shank, G. Christopher; Evans, Anne

    2011-07-01

    The distribution and photoreactivity of chromophoric dissolved organic matter (CDOM) in the northern Gulf of Mexico along the Louisiana coastal shelf were examined during three cruises in summer 2007, fall 2007, and summer 2008. The influence of the Mississippi River plume was clearly evident as CDOM levels (defined as a305) and dissolved organic carbon (DOC) concentrations were well-correlated with salinity during all cruises. Elevated CDOM and CDOM:DOC ratios of surface samples collected offshore of Atchafalaya Bay and the Breton-Chandeleur Sound complex indicated emanations of organic-rich waters from coastal wetlands are also an important source to nearshore shelf waters. Generally, CDOM and DOC levels were highest in surface waters and decreased with depth, but during summer 2007 and summer 2008, CDOM levels in near-bottom samples were occasionally higher than at mid-depths without concomitant increases in DOC. CDOM photobleaching was measured during 24 irradiations using a SunTest XLS+ solar simulator with photobleaching rate coefficients ( k305) ranging from 0.011 to 0.32 h -1. For fall 2007 and summer 2008, higher k305 values were generally observed in samples with higher initial CDOM levels. However, samples collected during summer 2007 did not exhibit a similar pattern nor were there differences in photobleaching rates between surface and bottom samples. Spectral slope coefficients ( S275-295 or S350-400) and DOC levels were largely unchanged after 24 h irradiations. Modeled CDOM photobleaching for northern Gulf of Mexico mid-shelf waters predicts that during the summer when solar irradiance is high and the water column becomes stratified, nearly 90% of the CDOM in the upper 1 m may be lost to photobleaching, with losses up to 20% possible even at 10 m depth.

  11. 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.

  12. 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.

    2013-06-01

    Even though dissolved organic carbon (DOC) is the most active carbon (C) cycling that takes place in soil organic carbon (SOC) pools, it is missing from the global C budget. Fluxes in DOC are critical to aquatic ecosystem inputs and contribute to C balances of terrestrial ecosystems. Only a 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 change in land use is of critical importance in regulating DOC leaching in temperate forests as an important source of C input to aquatic ecosystems.

  13. CLOSE STELLAR ENCOUNTERS IN YOUNG, SUBSTRUCTURED, DISSOLVING STAR CLUSTERS: STATISTICS AND EFFECTS ON PLANETARY SYSTEMS

    SciTech Connect

    Craig, Jonathan; Krumholz, Mark R., E-mail: krumholz@ucolick.org [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States)

    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.

  14. 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

  15. Nanomaterials in Biosolids Inhibit Nodulation, Shift Microbial Community Composition, and Result in Increased Metal Uptake Relative to Bulk/Dissolved Metals.

    PubMed

    Judy, Jonathan D; McNear, David H; Chen, Chun; Lewis, Ricky W; Tsyusko, Olga V; Bertsch, Paul M; Rao, William; Stegemeier, John; Lowry, Gregory V; McGrath, Steve P; Durenkamp, Mark; Unrine, Jason M

    2015-07-21

    We examined the effects of amending soil with biosolids produced from a pilot-scale wastewater treatment plant containing a mixture of metal-based engineered nanomaterials (ENMs) on the growth of Medicago truncatula, its symbiosis with Sinorhizobium meliloti, and on soil microbial community structure. Treatments consisted of soils amended with biosolids generated with (1) Ag, ZnO, and TiO2 ENMs introduced into the influent wastewater (ENM biosolids), (2) AgNO3, Zn(SO4)2, and micron-sized TiO2 (dissolved/bulk metal biosolids) introduced into the influent wastewater stream, or (3) no metal added to influent wastewater (control). Soils were amended with biosolids to simulate 20 years of metal loading, which resulted in nominal metal concentrations of 1450, 100, and 2400 mg kg(-1) of Zn, Ag, and Ti, respectively, in the dissolved/bulk and ENM treatments. Tissue Zn concentrations were significantly higher in the plants grown in the ENM treatment (182 mg kg(-1)) compared to those from the bulk treatment (103 mg kg(-1)). Large reductions in nodulation frequency, plant growth, and significant shifts in soil microbial community composition were found for the ENM treatment compared to the bulk/dissolved metal treatment. These results suggest differences in metal bioavailability and toxicity between ENMs and bulk/dissolved metals at concentrations relevant to regulatory limits. PMID:26061863

  16. An On-Line Monitoring System for Gases Dissolved in Transformer Oil Using Wireless Data Acquisition

    Microsoft Academic Search

    Xuezeng Zhao; Yangliu Li

    2009-01-01

    Dissolved gas analysis (DGA) is a certain method to diagnose incipient fault of transformers through the correlation between the content of gases dissolved in transformer oil and a particular malfunction. This paper developed an on-line monitoring system to detect the concentrations of H2 and CO dissolved in transformer oil. The system mounts polyperfluoro ethylene-propylene membrane, electrochemical gas sensors, a wireless

  17. Characterization of a fluorescent sol–gel encapsulated erythrosin B dissolved oxygen sensor

    Microsoft Academic Search

    R. T Bailey; F. R Cruickshank; G Deans; R. N Gillanders; M. C Tedford

    2003-01-01

    A thin film dissolved oxygen sensor was fabricated by trapping erythrosin B in a sol–gel matrix. No phosphorescence was observed when the sensor was immersed in water. Very weak phosphorescence was observed when erythrosin B was dissolved in aqueous ethanol and acetone solutions. However, fluorescence at 590nm, which was efficiently quenched by dissolved oxygen, was observed from the doped sol–gel

  18. Nutrient and dissolved-oxygen distributions in the Gulf of Mexico and adjacent regions 

    E-print Network

    Morrison, John Miller

    1974-01-01

    as to style and content by: (Chairman of Co ittee) (Head Department) (Member) (Me er) May &9yi) ABSTRACT Nutrient and. Dissolved-oxygen Distributions in the Gulf of Nexico and Adjacent Regions. (Nay 1974) John Miller Morrison~ B. A. , College... of the Holy Cross Directed. by: Dr. North D. Bowlin, Jr. Dissolved. silicate, d. issolved phosphate~ and dissolved oxygen were used in the Gulf of Mexico and adjacent regions to study the current regime and, water mass distribu?ion. Vertical sections...

  19. Long-pulsed luminescence for the measurement of dissolved oxygen.

    PubMed

    Fitzgerald, Noel S; Burgess, Lloyd W; Yang, Jeffrey C-Y; Kim, Prince J; Jang, Sei-Hum; Jen, Alex K-Y

    2014-01-01

    Thin-film luminescent sensors were used to measure dissolved oxygen in picoliter volumes for the purpose of monitoring single-cell oxygen consumption rates, and that work served as the motivation for the development of the method described here. A few different platinum porphyrin sensor materials were examined, with all measurements conducted microscopically. By employing convolution theory to understand observed responses, including an unexpected red luminescent emission from an optic, we developed a new, rapid method for the determination of exponential decay lifetime. This new method of long-pulsed luminescence offers substantially improved signal-to-noise ratios for detected signals as long as self-illumination sources are carefully controlled in the experimental set-up. PMID:24666948

  20. Corals concentrate dissolved inorganic carbon to facilitate calcification.

    PubMed

    Allison, Nicola; Cohen, Itay; Finch, Adrian A; Erez, Jonathan; Tudhope, Alexander W

    2014-01-01

    The sources of dissolved inorganic carbon (DIC) used to produce scleractinian coral skeletons are not understood. Yet this knowledge is essential for understanding coral biomineralization and assessing the potential impacts of ocean acidification on coral reefs. Here we use skeletal boron geochemistry to reconstruct the DIC chemistry of the fluid used for coral calcification. We show that corals concentrate DIC at the calcification site substantially above seawater values and that bicarbonate contributes a significant amount of the DIC pool used to build the skeleton. Corals actively increase the pH of the calcification fluid, decreasing the proportion of DIC present as CO2 and creating a diffusion gradient favouring the transport of molecular CO2 from the overlying coral tissue into the calcification site. Coupling the increases in calcification fluid pH and [DIC] yields high calcification fluid [CO3(2-)] and induces high aragonite saturation states, favourable to the precipitation of the skeleton. PMID:25531981

  1. Adsorptive fractionation of dissolved organic matter (DOM) by carbon nanotubes.

    PubMed

    Engel, Maya; Chefetz, Benny

    2015-02-01

    Dissolved organic matter (DOM) and carbon nanotubes are introduced into aquatic environments. Thus, it is important to elucidate whether their interaction affects DOM amount and composition. In this study, the composition of DOM, before and after interactions with single-walled carbon nanotubes (SWCNTs), was measured and the adsorption affinity of the individual structural fractions of DOM to SWCNTs was investigated. Adsorption of DOM to SWCNTs was dominated by the hydrophobic acid fraction, resulting in relative enhancement of the hydrophilic character of non-adsorbed DOM. The preferential adsorption of the HoA fraction was concentration-dependent, increasing with increasing concentration. Adsorption affinities of bulk DOM calculated as the normalized sum of affinities of the individual structural fractions were similar to the measured affinities, suggesting that the structural fractions of DOM act as independent adsorbates. The altered DOM composition may affect the nature and reactivity of DOM in aquatic environments polluted with carbon nanotubes. PMID:25480440

  2. Measurement of dissolved carbon dioxide using colorimetric polymer films

    NASA Astrophysics Data System (ADS)

    Mills, Andrew; Wild, Lorraine

    1995-01-01

    The hydrophobic bases tetradodecylammonium hydroxide (TDAOH) and tetrakisdecylammonium hydroxide (TKAOH) are to be used to solubilize the anionic form of m-cresol purple in ethyl cellulose to create a dry colorimetric thin polymer film sensor for CO2 in the gas phase or dissolved in solution. When used in aqueous solution, both TDAOH and TKAOH appear significantly more resistant to interference by protons or other ions at high concentration when compared with tetraoctylammonium hydroxide (TOAOH), the hydrophobic base which has been used for such work in previous studies. The TDAOH films are used as carbon dioxide sensors in aqueous solution at high ionic strength (e.g. 1 mol dm-3) and still appear blue at pH 1 after 1 h.

  3. Bacterial biomarkers thermally released from dissolved organic matter

    USGS Publications Warehouse

    Greenwood, P.F.; Leenheer, J.A.; McIntyre, C.; Berwick, L.; Franzmann, P.D.

    2006-01-01

    Hopane biomarker products were detected using microscale sealed vessel (MSSV) pyrolysis gas chromatography-mass spectrometry (GC-MS) analysis of dissolved organic matter from natural aquatic systems colonised by bacterial populations. MSSV pyrolysis can reduce the polyhydroxylated alkyl side chain of bacteriohopanepolyols, yielding saturated hopane products which are more amenable to GC-MS detection than their functionalised precursors. This example demonstrates how the thermal conditions of MSSV pyrolysis can reduce the biologically-inherited structural functionality of naturally occurring organic matter such that additional structural fragments can be detected using GC methods. This approach complements traditional analytical pyrolysis methods by providing additional speciation information useful for establishing the structures and source inputs of recent or extant organic material. ?? 2006.

  4. Refractory dissolved organic nitrogen accumulation in high-elevation lakes.

    PubMed

    Goldberg, S J; Ball, G I; Allen, B C; Schladow, S G; Simpson, A J; Masoom, H; Soong, R; Graven, H D; Aluwihare, L I

    2015-01-01

    The role of dissolved organic matter (DOM) as either a sink for inorganic nutrients or an additional nutrient source is an often-neglected component of nutrient budgets in aquatic environments. Here, we examined the role of DOM in reactive nitrogen (N) storage in Sierra Nevada (California, USA) lakes where atmospheric deposition of N has shifted the lakes toward seasonal phosphorus (P)-limitation. Nuclear magnetic resonance (NMR) spectroscopy and isotope analyses performed on DOM isolated from Lake Tahoe reveal the accumulation of refractory proteinaceous material with a 100-200-year residence time. In contrast, smaller lakes in the same watershed contain DOM with typical terrestrial characteristics, indicating that proteins in Lake Tahoe are autochthonously produced. These data support the role of DOM as a possible sink for reactive N in these lake ecosystems and identify a potential role for DOM in affecting the inorganic nutrient stoichiometry of these environments. PMID:25704539

  5. Diverse stoichiometry of dissolved trace metals in the Indian Ocean

    PubMed Central

    Thi Dieu Vu, Huong; Sohrin, Yoshiki

    2013-01-01

    Trace metals in seawater are essential to organisms and important as tracers of various processes in the ocean. However, we do not have a good understanding of the global distribution and cycling of trace metals, especially in the Indian Ocean. Here we report the first simultaneous, full-depth, and basin-scale section-distribution of dissolved (D) Al, Mn, Fe, Co, Ni, Cu, Zn, Cd, and Pb in the Indian Ocean. Our data reveal widespread co-limitation for phytoplankton production by DFe and occurrence of redox-related processes. The stoichiometry of the DM/phosphorus ratio agrees within a factor of 5 between deep waters in the Indian and Pacific, whereas it shows variability up to a factor of 300 among water masses within the Indian Ocean. This indicates that a consistent mechanism controls the stoichiometry in the deep waters, which are significantly depleted in Mn, Fe, and Co compared to requirements for phytoplankton.

  6. The role of dissolved cations in coffee extraction.

    PubMed

    Hendon, Christopher H; Colonna-Dashwood, Lesley; Colonna-Dashwood, Maxwell

    2014-05-28

    The flavorsome compounds in coffee beans exist in the form of aprotic charge neutral species, as well as a collection of acids and conjugate salts. The dissolution and extraction of these organic molecules is a process dependent on the dissolved mineral content of the water. It is known that different rates and compositions of coffee extraction are achieved through the control of the water "impurities", Na(+), Mg(2+), and Ca(2+), which coordinate to nucleophilic motifs in coffee. Using density functional theory, we quantify the thermodynamic binding energies of five familiar coffee-contained acids, caffeine, and a representative flavor component, eugenol. From this, we provide insight into the mechanism and ideal mineral composition of water for extraction of flavorsome compounds in coffee. PMID:24802110

  7. Removal of dissolved heavy metals and radionuclides by microbial spores

    SciTech Connect

    Revis, N.W.; Hadden, C.T.; Edenborn, H. [and others

    1997-11-01

    Microbial systems have been shown to remove specific heavy metals from contaminated aqueous waste to levels acceptable to EPA for environmental release. However, systems capable of removing a variety of heavy metals from aqueous waste to environmentally acceptable levels remain to be reported. The present studies were performed to determine the specificity of spores of the bacterium Bacillus megaterium for the adsorption of dissolved metals and radionuclides from aqueous waste. The spores effectively adsorbed eight heavy metals from a prepared metal mix and from a plating rinse waste to EPA acceptable levels for waste water. These results suggest that spores have multiple binding sites for the adsorption of heavy metals. Spores were also effective in adsorbing the radionuclides {sup 85}strontium and {sup 197}cesium. The presence of multiple sites in spores for the adsorption of heavy metals and radionuclides makes this biosorbent a good candidate for the treatment of aqueous wastes associated with the plating and nuclear industries. 17 refs., 4 tabs.

  8. Carbon nanotubes: are they dispersed or dissolved in liquids?

    NASA Astrophysics Data System (ADS)

    Geckeler, Kurt Ernst; Premkumar, Thathan

    2011-12-01

    Carbon nanotubes (CNTs) constitute a novel class of nanomaterials with remarkable applications in diverse domains. However, the main intrincsic problem of CNTs is their insolubility or very poor solubility in most of the common solvents. The basic key question here is: are carbon nanotubes dissolved or dispersed in liquids, specifically in water? When analyzing the scientific research articles published in various leading journals, we found that many researchers confused between "dispersion" and "solubilization" and use the terms interchangeably, particularly when stating the interaction of CNTs with liquids. In this article, we address this fundamental issue to give basic insight specifically to the researchers who are working with CNTs as well asgenerally to scientists who deal with nano-related research domains.

  9. Carbon nanotubes: are they dispersed or dissolved in liquids?

    PubMed Central

    2011-01-01

    Carbon nanotubes (CNTs) constitute a novel class of nanomaterials with remarkable applications in diverse domains. However, the main intrincsic problem of CNTs is their insolubility or very poor solubility in most of the common solvents. The basic key question here is: are carbon nanotubes dissolved or dispersed in liquids, specifically in water? When analyzing the scientific research articles published in various leading journals, we found that many researchers confused between "dispersion" and "solubilization" and use the terms interchangeably, particularly when stating the interaction of CNTs with liquids. In this article, we address this fundamental issue to give basic insight specifically to the researchers who are working with CNTs as well asgenerally to scientists who deal with nano-related research domains. PMID:21711654

  10. Dissolved and particulate carbohydrates in contrasting marine sediments

    NASA Astrophysics Data System (ADS)

    Burdige, D. J.; Skoog, A.; Gardner, K.

    2000-03-01

    Dissolved and particulate carbohydrates were examined in contrasting Chesapeake Bay (estuarine) and mid-Atlantic shelf/slope break (continental margin) sediments. Particulate carbohydrates (PCHOs) represented ˜5-9% of the total sediment particulate organic carbon (POC), and PCHO remineralization appeared to be a similar fraction of total sediment carbon oxidation (or C ox). When these results are compared with results from other coastal sediments and a pelagic turbidite, PCHO remineralization (as a percentage of C ox) did not vary by more than a factor of ˜2-3 over a 3-4 order of magnitude range in C ox values. The causes of this are not well understood, but may be related to specific effects associated with the remineralization of highly altered organic matter mixtures under aerobic conditions. Dissolved carbohydrates (DCHOs) in these sediment pore waters ranged from ˜30 to 400 ?M, increased with depth in a manner similar to total DOC, and represented ˜10 to 55% of pore water DOC. In Chesapeake Bay sediments this percentage decreased with sediment depth, while in these continental margin sediments it was constant (upper 30 cm). Of the DCHOs in these pore waters ˜30 to 50% could be identified as individual aldoses (monomeric neutral sugars), and total aldose yields (individual aldoses as a percentage of total DOC) were higher in these continental margin sediment pore waters (>9%) than they were in the estuarine sediment pore waters (<5%). A comparison of DCHO and PCHO concentrations in these sediments indicates that their concentrations are uncoupled, and that pore water DCHO concentrations are primarily controlled by sediment remineralization processes. Pore water DCHOs appeared to be preferentially found in the high molecular weight (HMW) DOC pool, and likely occur as some of the initial HMW intermediates produced and consumed during sediment POC remineralization. These results also support past suggestions about the differing controls on carbon remineralization processes in continental margin versus estuarine sediments.

  11. Dissolved organic carbon (DOC) in Arctic ground ice

    NASA Astrophysics Data System (ADS)

    Fritz, M.; Opel, T.; Tanski, G.; Herzschuh, U.; Meyer, H.; Eulenburg, A.; Lantuit, H.

    2015-04-01

    Thermal permafrost degradation and coastal erosion in the Arctic remobilize substantial amounts of organic carbon (OC) and nutrients which have accumulated in late Pleistocene and Holocene unconsolidated deposits. Permafrost vulnerability to thaw subsidence, collapsing coastlines and irreversible landscape change are largely due to the presence of large amounts of massive ground ice such as ice wedges. However, ground ice has not, until now, been considered to be a source of dissolved organic carbon (DOC), dissolved inorganic carbon (DIC) and other elements which are important for ecosystems and carbon cycling. Here we show, using biogeochemical data from a large number of different ice bodies throughout the Arctic, that ice wedges have the greatest potential for DOC storage, with a maximum of 28.6 mg L-1 (mean: 9.6 mg L-1). Variation in DOC concentration is positively correlated with and explained by the concentrations and relative amounts of typically terrestrial cations such as Mg2+ and K+. DOC sequestration into ground ice was more effective during the late Pleistocene than during the Holocene, which can be explained by rapid sediment and OC accumulation, the prevalence of more easily degradable vegetation and immediate incorporation into permafrost. We assume that pristine snowmelt is able to leach considerable amounts of well-preserved and highly bioavailable DOC as well as other elements from surface sediments, which are rapidly frozen and stored in ground ice, especially in ice wedges, even before further degradation. We found that ice wedges in the Yedoma region represent a significant DOC (45.2 Tg) and DIC (33.6 Tg) pool in permafrost areas and a freshwater reservoir of 4200 km2. This study underlines the need to discriminate between particulate OC and DOC to assess the availability and vulnerability of the permafrost carbon pool for ecosystems and climate feedback upon mobilization.

  12. Priming the Dissolved Organic Matter Breakdown in Urban Streams

    NASA Astrophysics Data System (ADS)

    Parr, T.; Cronan, C. S.; Ohno, T.; Simon, K. S.

    2014-12-01

    Land use and land cover change in the Anthropocene have altered the source, composition, and reactivity of dissolved organic matter (DOM) in aquatic ecosystems around the world. In particular, urbanization increases the abundance of bioavailable DOM in streams. This bioavailable DOM may increase the utilization of less bioavailable pools of DOM via the "priming effect." The priming effect is a phenomenon whereby the addition of a small amount of labile DOM can increase or decrease the breakdown rate of less bioavailable DOM - positive and negative priming respectively. Our research tests priming as one potential mechanism altering DOM composition and increasing its bioavailability in urban streams. We measured DOM degradation during 30-day incubations in samples from a small urban stream and two microbial DOM sources mixed with DOM from a small stream dominated by less microbial allochthonous sources. We assessed priming by looking at observed percent biodegradable dissolved organic carbon (BDOC) vs. endmember predicted BDOC. We also investigated the molecular dynamics of priming using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR/MS). Using bulk DOC concentration we found evidence that adding small amounts of DOM from an urban stream could increase BDOC by a factor of two to three. At the molecular level, FT-ICR/MS showed that addition of labile DOM may increase the bioavailability of a variety of compound classes including proteins, lipids, and "black carbon." Furthermore, we observed that what is frequently reported as positive or negative priming may be more accurately understood as the net balance of simultaneous positive and negative priming operating on different DOM pools. Our results highlight an important global mechanism by which human activities may alter the composition and reactivity of DOM in fresh waters. Priming the degradation of allochthonous DOM with autochthonous or novel anthropogenic DOM may alter the organic energy available for microbially driven ecosystem functions regulating water quality.

  13. Evaluation and validation of criticality codes for fuel dissolver calculations

    SciTech Connect

    Santamarina, A.; Smith, H.J. (CEA Centre d'Etudes Nucleaires de Cadarache, 13 - Saint-Paul-lez-Durance (France)); Whitesides, G.E. (Oak Ridge National Lab., TN (United States))

    1991-01-01

    During the past ten years an OECD/NEA Criticality Working Group has examined the validity of criticality safety computational methods. International calculation tools which were shown to be valid in systems for which experimental data existed were demonstrated to be inadequate when extrapolated to fuel dissolver media. The spread of the results in the international calculation amounted to {plus minus} 12,000 pcm in the realistic fuel dissolver exercise n{degrees} 19 proposed by BNFL, and to {plus minus} 25,000 pcm in the benchmark n{degrees} 20 in which fissile material in solid form is surrounded by fissile material in solution. A theoretical study of the main physical parameters involved in fuel dissolution calculations was performed, i.e. range of moderation, variation of pellet size and the fuel double heterogeneity effect. The APOLLO/P{sub IC} method developed to treat latter effect, permits us to supply the actual reactivity variation with pellet dissolution and to propose international reference values. The disagreement among contributors' calculations was analyzed through a neutron balance breakdown, based on three-group microscopic reaction rates solicited from the participants. The results pointed out that fast and resonance nuclear data in criticality codes are not sufficiently reliable. Moreover the neutron balance analysis emphasized the inadequacy of the standard self-shielding formalism (NITAWL in the international SCALE package) to account for {sup 238}U resonance mutual self-shielding in the pellet-fissile liquor interaction. Improvements in the up-dated 1990 contributions, as do recent complementary reference calculations (MCNP, VIM, ultrafine slowing-down CGM calculation), confirm the need to use rigorous self-shielding methods in criticality design-oriented codes. 6 refs., 11 figs., 3 tabs.

  14. Updated determination of particulate and dissolved thorium-234

    NASA Astrophysics Data System (ADS)

    Fleer, Alan P.

    The determination of particulate and dissolved 234Th is similar to the procedure of Anderson and Fleer [1982]. Samples are collected using 30 L Niskin bottles with Teflon- or epoxy-coated internal springs. On deck, the sample is pumped with a delrin impeller pump through a 0.45 ?m pore size 147-mm diameter Millipore filter and into a pre-rinsed 6 gallon plastic cubitainer held in a plastic milk crate. An in-line plastic water meter records volumes in gallons. The particulate sample filter is folded twice and stored in a polyethylene sample bag. To the ˜20 L filtered sample is added: 30 mL reagent grade 16 N HNO3; 500 mL 230Th tracer of ˜30 dpm mL-l and 5 mL 50 mg mL-l iron carrier previously cleaned by extraction into isopropyl ether from an 8 M HCl solution and back-extracted into 0.1 M HCl. The acidified sample is allowed to equilibrate for from one day to a maximum of several days. The sample is weighed on a Heathkit digital scale and the pH is adjusted to approximately 8 with about 40 mL 10 M NH4OH to precipitate iron hydroxide, which carries the thorium and uranium from the solution. The precipitate is allowed to settle for 12 to 24 hours. The supernate is drawn off, and the precipitate is spun down in a centrifuge tube to about an 8 mL volume. The precipitate is resuspended in distilled water and spun down again, then dissolved in three times its volume with 12 N HCl to make a 9 N HCl solution. A 1.5 cm×12 cm ion exchange column is filled with AG1×8 100-200 mesh resin and conditioned with 9 N HCl. The sample solution is run slowly through.

  15. Modeling impact of storage zones on stream dissolved oxygen

    USGS Publications Warehouse

    Chapra, S.C.; Runkel, R.L.

    1999-01-01

    The Streeter-Phelps dissolved oxygen model is modified to incorporate storage zones. A dimensionless number reflecting enhanced decomposition caused by the increased residence time of the biochemical oxygen demand in the storage zone parameterizes the impact. This result provides a partial explanation for the high decomposition rates observed in shallow streams. An application suggests that the storage zone increases the critical oxygen deficit and moves it closer to the point source. It also indicates that the storage zone should have lower oxygen concentration than the main channel. An analysis of a dimensionless enhancement factor indicates that the biochemical oxygen demand decomposition in small streams could be up to two to three times more than anticipated based on the standard Streeter-Phelps model without storage zones. For larger rivers, enhancements of up to 1.5 could occur.The Streeter-Phelps dissolved oxygen model is modified to incorporate storage zones. A dimensionless number reflecting enhanced decomposition caused by the increased residence time of the biochemical oxygen demand in the storage zone parameterizes the impact. This result provides a partial explanation for the high decomposition rates observed in shallow streams. An application suggests that the storage zone increases the critical oxygen deficit and moves it closer to the point source. It also indicates that the storage zone should have lower oxygen concentration than the main channel. An analysis of a dimensionless enhancement factor indicates that the biochemical oxygen demand decomposition in small streams could be up to two to three times more than anticipated based on the standard Streeter-Phelps model without storage zones. For larger rivers, enhancements of up to 1.5 could occur.

  16. Molecular characterization of dissolved organic matter (DOM): a critical review.

    PubMed

    Nebbioso, Antonio; Piccolo, Alessandro

    2013-01-01

    Advances in water chemistry in the last decade have improved our knowledge about the genesis, composition, and structure of dissolved organic matter, and its effect on the environment. Improvements in analytical technology, for example Fourier-transform ion cyclotron (FT-ICR) mass spectrometry (MS), homo and hetero-correlated multidimensional nuclear magnetic resonance (NMR) spectroscopy, and excitation emission matrix fluorimetry (EEMF) with parallel factor (PARAFAC) analysis for UV-fluorescence spectroscopy have resulted in these advances. Improved purification methods, for example ultrafiltration and reverse osmosis, have enabled facile desalting and concentration of freshly collected DOM samples, thereby complementing the analytical process. Although its molecular weight (MW) remains undefined, DOM is described as a complex mixture of low-MW substances and larger-MW biomolecules, for example proteins, polysaccharides, and exocellular macromolecules. There is a general consensus that marine DOM originates from terrestrial and marine sources. A combination of diagenetic and microbial processes contributes to its origin, resulting in refractory organic matter which acts as carbon sink in the ocean. Ocean DOM is derived partially from humified products of plants decay dissolved in fresh water and transported to the ocean, and partially from proteinaceous and polysaccharide material from phytoplankton metabolism, which undergoes in-situ microbial processes, becoming refractory. Some of the DOM interacts with radiation and is, therefore, defined as chromophoric DOM (CDOM). CDOM is classified as terrestrial, marine, anthropogenic, or mixed, depending on its origin. Terrestrial CDOM reaches the oceans via estuaries, whereas autochthonous CDOM is formed in sea water by microbial activity; anthropogenic CDOM is a result of human activity. CDOM also affects the quality of water, by shielding it from solar radiation, and constitutes a carbon sink pool. Evidence in support of the hypothesis that part of marine DOM is of terrestrial origin, being the result of a long-term carbon sedimentation, has been obtained from several studies discussed herein. PMID:22965531

  17. Dissolved-Solids Transport in Surface Water of the Muddy Creek Basin, Utah

    USGS Publications Warehouse

    Gerner, Steven J.

    2008-01-01

    Muddy Creek is located in the southeastern part of central Utah and is a tributary of the Dirty Devil River, which, in turn, is a tributary of the Colorado River. Dissolved solids transported from the Muddy Creek Basin may be stored in the lower Dirty Devil River Basin, but are eventually discharged to the Colorado River and impact downstream water users. This study used selected dissolved-solids measurements made by various local, State, and Federal agencies from the 1970s through 2006, and additional dissolved-solids data that were collected by the U.S. Geological Survey during April 2004 through November 2006, to compute dissolved-solids loads, determine the distribution of dissolved-solids concentrations, and identify trends in dissolved-solids concentration in surface water of the Muddy Creek Basin. The dissolved-solids concentration values measured in water samples collected from Muddy Creek during April 2004 through October 2006 ranged from 385 milligrams per liter (mg/L) to 5,950 mg/L. The highest dissolved-solids concentration values measured in the study area were in water samples collected at sites in South Salt Wash (27,000 mg/L) and Salt Wash (4,940 to 6,780 mg/L). The mean annual dissolved-solids load in Muddy Creek for the periods October 1976 to September 1980 and October 2005 to September 2006 was smallest at a site near the headwaters (9,670 tons per year [tons/yr]) and largest at a site at the mouth (68,700 tons/yr). For this period, the mean annual yield of dissolved solids from the Muddy Creek Basin was 44 tons per square mile. During October 2005 to September 2006, direct runoff transported as much as 45 percent of the annual dissolved-solids load at the mouth of Muddy Creek. A storm that occurred during October 5?7, 2006 resulted in a peak streamflow at the mouth of Muddy Creek of 7,150 cubic feet per second (ft3/s) and the transport of an estimated 35,000 tons of dissolved solids, which is about 51 percent of the average annual dissolved-solids load at the mouth of Muddy Creek. A significant downward trend in dissolved-solids concentrations from 1973 to 2006 was determined for Muddy Creek at a site just downstream of that portion of the basin containing agricultural land. Dissolved-solids concentrations decreased about 2.1 percent per year; however, the rate of change was a decrease of 1.8 percent per year when dissolved-solids concentrations were adjusted for flow.

  18. A Simple, Buoy Deployable Instrument for Accurate Dissolved Carbon Dioxide and Dissolved Inorganic Carbon Measurements in Freshwater and Marine Ecosystems

    NASA Astrophysics Data System (ADS)

    Browne, B. A.; Wyss, J. R.; Bowling, J. M.; Schueller, D. J.; Sherman, J. F.

    2007-05-01

    The need for better knowledge of (1) the oceanic sink for anthropogenic CO2, (2) the impact of anthropogenic CO2 on the oceanic CaCO3 system and (3) lake and stream metabolism in freshwater ecosystems is driving growing interest in real-time technologies to measure pCO2 and dissolved inorganic carbon (DIC). To be useful, these technologies must meet stringent data quality requirements of marine and freshwater biogeochemical research initiatives such as the Joint Global Ocean Flux Study, the Coral Reef Environmental Observatory Network, the National Ecological Observatory Network, and the Global Lake Ecological Observatory Network. In this presentation, we introduce new methodology and a device for unaccompanied measurement of pCO2 and DIC on research buoys or ocean/freshwater vessels. This small-scale, essentially "plug and play" device (shoe box size) has limited power requirements (?1.8 amps) for continuous or discontinuous (e.g., one reading per hour) measurements and does not bio-foul. DIC and pCO2 can be measured in sequence using one infrared detector or in parallel using two. The accuracy and precision (<0.15% coefficient of variation) for pCO2 and DIC meet or approximate the data quality requirements for large-scale biogeochemical research initiatives. Training requirements are minimal, providing flexibility for deployments on multiple vessel types. The device works by induction of ebullition. A hydrostatic pressure drop upstream of a pump causes a temporary condition of gas oversaturation. The collection cell downstream of the pump then acts like an overpressurized soda bottle. As pressure is released within the collection cell, the dissolved gas streams passively and reliably into the infrared detector(s), at a nominal rate of 7 mL per minute, carrying CO2 into the cell essentially at its in-situ partial pressure. To measure DIC, a valve allows for the addition of acid to the sampling line upstream of the pump converting all DIC to CO2 prior to reaching the collection cell. With the acid valve on, DIC is measured. With the acid valve off, pCO2 is measured. We will present data illustrating the accuracy and precision of this device in both laboratory and field circumstances. We will also show the unique possibility of coupling not only pCO2 and DIC in one device, but dissolved organic carbon as well.

  19. 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.

  20. Fate of Allochthonous Dissolved Organic Carbon in Lakes: A Quantitative Approach

    PubMed Central

    Hanson, Paul C.; Hamilton, David P.; Stanley, Emily H.; Preston, Nicholas; Langman, Owen C.; Kara, Emily L.

    2011-01-01

    Inputs of dissolved organic carbon (DOC) to lakes derived from the surrounding landscape can be stored, mineralized or passed to downstream ecosystems. The balance among these OC fates depends on a suite of physical, chemical, and biological processes within the lake, as well as the degree of recalcintrance of the allochthonous DOC load. The relative importance of these processes has not been well quantified due to the complex nature of lakes, as well as challenges in scaling DOC degradation experiments under controlled conditions to the whole lake scale. We used a coupled hydrodynamic-water quality model to simulate broad ranges in lake area and DOC, two characteristics important to processing allochthonous carbon through their influences on lake temperature, mixing depth and hydrology. We calibrated the model to four lakes from the North Temperate Lakes Long Term Ecological Research site, and simulated an additional 12 ‘hypothetical’ lakes to fill the gradients in lake size and DOC concentration. For each lake, we tested several mineralization rates (range: 0.001 d?1 to 0.010 d?1) representative of the range found in the literature. We found that mineralization rates at the ecosystem scale were roughly half the values from laboratory experiments, due to relatively cool water temperatures and other lake-specific factors that influence water temperature and hydrologic residence time. Results from simulations indicated that the fate of allochthonous DOC was controlled primarily by the mineralization rate and the hydrologic residence time. Lakes with residence times <1 year exported approximately 60% of the DOC, whereas lakes with residence times >6 years mineralized approximately 60% of the DOC. DOC fate in lakes can be determined with a few relatively easily measured factors, such as lake morphometry, residence time, and temperature, assuming we know the recalcitrance of the DOC. PMID:21779347

  1. The distribution of dissolved and total dissolvable aluminum in the Beaufort Sea and Canada Basin region of the Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Giesbrecht, Timothy; Sim, Nari; Orians, Kristin J.; Cullen, Jay T.

    2013-12-01

    Vertical profiles of the concentrations of dissolved Al [D-Al] and total dissolvable Al [T-Al] are reported from a transect extending from the continental shelf of the Beaufort Sea into the Canada Basin in the Arctic Ocean. Sampling was performed in late summer and early autumn 2007, a year of historically extensive sea-ice melt. Vertical profiles of [D-Al] displayed surface maxima (1-3 nmol kg-1), subsurface minima (<1 nmol kg-1) in the upper halocline layer (Upper HL; 50-200 m), and a general increase in concentration with depth to values of ˜5-10 nmol kg-1. Near surface maxima at this time were associated with relatively fresh surface waters (26-30) resulting from sea-ice melt in the region. This observation supports sea ice with entrained sediments and surface deposition of aerosols as important mechanisms for the delivery of Al to surface waters of the Canada Basin. No correlation between D-Al and silicic acid was observed and low D-Al:Si ratios in waters >300 m depth suggest that Al is likely lost through particle scavenging in the interior of the Canada Basin. Concentrations of T-Al show that particulate Al (>0.2 µm) is the dominant form of Al in the water column except at greater depths at the most offshore stations. Lateral transport of D-Al and T-Al off the shelf likely results from the offshore progression of cyclonic eddies spawned inshore, oscillating upwelling and downwelling favorable winds, and brine rejection during sea-ice formation that can drive currents sufficiently energetic to resuspend shelf sediments.

  2. Changes in dissolved organic carbon and total dissolved nitrogen fluxes across subtropical forest ecosystems at different successional stages

    NASA Astrophysics Data System (ADS)

    Yan, Junhua; Li, Kun; Wang, Wantong; Zhang, Deqiang; Zhou, Guoyi

    2015-05-01

    Lateral transports of carbon and nitrogen are important processes linking terrestrial ecosystems and aquatic systems. Most previous studies made in temperate forests found that fluxes of carbon and nitrogen by runoff water varied in different forests, but few studies have been made in subtropical forests. This study was to investigate dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) fluxes at the catchment scale along a subtropical forest succession gradient from pine forest (pioneer) to coniferous and broadleaved mixed forest (transitional) to broadleaved forest (mature). Our results showed that DOC concentration significantly decreased (p<0.001) while TDN concentration significantly increased (p<0.001) in runoff water from pioneer to mature forests, which in turn resulted in a decrease in DOC flux and an increase in TDN flux, as mean annual runoff did not vary significantly among three succession forest catchments. The mean (±standard deviation) annual DOC flux was 118.1±43.6, 88.3±16.7 and 77.2±11.7 kg ha-1 yr-1for pioneer, transitional and mature forest catchments, respectively; and the mean annual TDN flux was 9.9 ±2.7, 18.2±3.0 and 21.2 ±4.5 kg ha-1 yr-1for pioneer, transitional and mature forest catchments, respectively. The mature forest reduced DOC flux by increased soil chemical adsorption and physical protection. An increase in TDN flux from pioneer to mature forests was consistent with the previous finding that mature forest was nitrogen saturated while pioneer forest was nitrogen limited. Therefore large-scale conversion of pioneer forests to transitional or mature forests in subtropical China will reduce DOC concentration and increase TDN concentration in the down-stream water, which may have significant impact on its water quality and aquatic biological activities.

  3. Association of Dissolved Mercury with Dissolved Organic Carbon in Rivers and Streams: The Role of Watershed Soil Organic Carbon

    NASA Astrophysics Data System (ADS)

    Stoken, O.; Riscassi, A.; Scanlon, T. M.

    2014-12-01

    Surface waters are an important pathway for the transport of atmospherically deposited mercury (Hg) from terrestrial watersheds. Dissolved Hg (HgD) is thought to be more bioavailable than particulate Hg and has been found to be strongly correlated with dissolved organic carbon (DOC) in numerous watersheds. The ratio of HgD to DOC is highly variable from site to site, which we hypothesize is strongly dependent on local environmental factors such as atmospheric deposition and soil organic carbon (SOC). Sixteen watersheds throughout the United States were used in this study to determine the relationship between the ratio of HgD:DOC, Hg wet deposition, and SOC. The Soil Survey Geographic database (SSURGO) and Northern Circumpolar Soil Carbon Database (NCSCD) were used to determine SOC values while HgD:DOC values were obtained from previous studies. Hg wet deposition was reported by the Mercury Deposition Network. There was no correlation found between atmospheric mercury wet deposition and HgD:DOC (r2 = 0.04; p = 0.44) but SOC was able to explain about 71% of the variation in the HgD:DOC ratio (r2 = 0.71; p < 0.01). A mathematical framework was developed to explain the power-law relationship between SOC and HgD:DOC based on soil carbon pools. The framework infers that the amount of Hg adsorbed to SOC does not increase in proportion to SOC at high SOC levels and points towards a Hg supply limitation for adsorption to soils with relatively deep carbon pools. Overall, this study identifies SOC as a first-order control on the association of HgD and DOC and indicates that globally available SOC datasets can be utilized to predict Hg transport in stream systems.

  4. An environmental simulation of a shrimp mariculture pond 

    E-print Network

    Whitson, John Lee

    1989-01-01

    Model Trophic Structure Nutrient Pool Dissolved Oxygen . Discussion 16 16 17 BASELINE SIMULATIONS 18 Semi-Intensive Stocking Density Empty Pond (No shrimp) . Comparison Discussion 18 25 25 29 SENSITIVITY ANALYSIS 30 Primary Producers... . Zooplankton 30 33 EVALUATION OF MANAGEMENT STRATEGIES . . 46 Evaluation of Stocking Densities and Feeding Rates 46 SUMMARY . REFERENCES 59 60 VITA 67 vss LIST OF FIGURES Figure Page 1 Pond Model Biomass Flows 2 Dissolved Oxygen and Population...

  5. Some theories of dissolved gas release from Tank 241-SY-101

    SciTech Connect

    Allemann, R.T.

    1994-09-01

    This report explains the ammonia release data to an order of magnitude agreement by the combination of three mechanisms of release: (1) bubble transport, (2) permeation/diffusion through the upper layers of the waste, and (3) diffusion/evaporation from freshly exposed liquid surfaces. Bounded by these mechanisms, there is low danger of extremely high ammonia concentrations in the off gas. This condition would occur through some (unlikely) continuous replenishing of fresh liquid on the surface. This would not occur unless there were continuous energetic rollovers, which seem very unlikely given historical evidence, or by energetic mixing of the waste with more power than provided by the current mixing pump. Nitrous oxide is of low solubility in the waste and behaves similarly to hydrogen.

  6. Plant diversity effects on leaching of nitrate, ammonium, and dissolved organic nitrogen from an experimental grassland

    NASA Astrophysics Data System (ADS)

    Leimer, Sophia; Oelmann, Yvonne; Wirth, Christian; Wilcke, Wolfgang

    2014-05-01

    Leaching of nitrogen (N) from soil represents a resource loss and, in particular leaching of nitrate, can threaten drinking water quality. As plant diversity leads to a more exhaustive resource use, we investigated the effects of plant species richness, functional group richness, and the presence of specific functional groups on nitrate, ammonium, dissolved organic N (DON), and total dissolved N (TDN) leaching from an experimental grassland in the first 4 years after conversion from fertilized arable land to unfertilized grassland. The experiment is located in Jena, Germany, and consists of 82 plots with 1, 2, 4, 8, 16, or 60 plant species and 1-4 functional groups (legumes, grasses, non-leguminous tall herbs, non-leguminous small herbs). Nitrate, ammonium, and TDN concentrations in soil solution in the 0-0.3 m soil layer were measured every second week during 4 years on 62 plots and DON concentrations were calculated as difference between TDN and inorganic N. Missing concentrations in soil solution were estimated using a Bayesian statistical model. Downward water fluxes (DF) per plot from the 0-0.3 m soil layer were simulated in weekly resolution with a water balance model in connection with a Bayesian model for simulating missing soil water content measurements. To obtain annual nitrate, ammonium, and DON leaching from the 0-0.3 m soil layer per plot, we multiplied the respective concentrations in soil solution with DF and aggregated the data to annual sums. TDN leaching resulted from summation of nitrate, ammonium, and DON leaching. DON leaching contributed most to TDN leaching, particularly in plots without legumes. Dissolved inorganic N leaching in this grassland was dominated by nitrate. The amount of annual ammonium leaching was small and little influenced by plant diversity. Species richness affected DON leaching only in the fourth and last investigated year, possibly because of a delayed soil biota effect that increased microbial transformation of organic N to inorganic N in species-rich mixtures or because of complementary resource use of amino-acid DON of species-rich mixtures. Nitrate and TDN leaching generally decreased with increasing species richness likely because of more exhaustive resource use of more diverse plant mixtures. Functional group richness did not have a significant effect on nitrate, ammonium, DON, and TDN leaching. Legumes increased and grasses decreased nitrate, DON, and TDN leaching because of their N-fixing ability and their extensive rooting system, respectively. TDN leaching was highest in the first year after conversion from arable to grassland which can be related to former fertilization. Quantitative differences in nitrate leaching between plant diversity treatments were also highest in the first year after conversion. However, the percentage reduction of nitrate leaching by species richness, the presence of grasses, or the presence of small herbs increased with time since land-use change possibly because of a strengthening of diversity effects with time. We conclude that especially shortly after land-use change from fertilized arable land to unfertilized grassland, N leaching, in particular nitrate leaching, can be reduced considerably if highly diverse mixtures without legumes are established.

  7. In-Situ Estuarine Measurements of Dissolved Cd, Cu and Pb Using a Voltammetric In-Situ Profiling (VIP) System

    NASA Astrophysics Data System (ADS)

    Achterberg, E. P.; Howell, K. A.; Braungardt, C. B.; Tappin, A. D.; Worsfold, P. J.

    2002-12-01

    In recent years there has been a trend from discrete seawater sample collection with laboratory based trace metal analysis to underway continuous sampling with automated ship-board analysis. This approach has resulted in minimization of contamination risk and enhanced spatial and temporal data resolution. The latest development in marine dissolved trace metal measurements involves the use of in-situ instrumentation that allows unattended determinations of Cd, Cu and Pb up to 500 m depths. The voltammetric in-situ profiling (VIP) system (Tercier et al., 1998, 2000) is based on anodic stripping voltammetry (ASV) and uses an agarose coated iridium based microarray as working electrode. This approach allows the measurement in seawater of subnanomolar concentrations of labile Cd, Cu and Pb species, with a size < ca. 2 nm. This presentation demonstrates results of analytical laboratory trials, in which the VIP system was subjected to simulated estuarine conditions. Also presented are the results of in-situ deployments of the VIP system showing dissolved VIP labile trace metal concentrations over a tidal cycle period in the Tamar and Fal Estuaries, England, and showing time series measurements of these metals in a Fjord in Sweden. Additional discrete total dissolved measurements indicate that an important fraction of Cu is organically complexed in these waters, in contrast with Pb. The research indicates that autonomous in-situ trace metal measurements in estuarine waters provides high resolution data which allow thorough a interpretation of biogeochemical processes in these systems. Tercier, M.L.; Buffle, J.; Graziottin, F., Electroanalysis, 1998, 10, 355-63. Tercier, M.L.; Pei J.; Buffle J., Electroanalysis, 2000, 12, 27-34.

  8. Dissolved Ti in the US GEOTRACES Atlantic Transect

    NASA Astrophysics Data System (ADS)

    Murray, R. W.; Moran, S.; Kelly, R. P.; Kelley, K. A.; Graham, D.

    2012-12-01

    The concentration of Ti in sediment and settling particles is often used as a lithogenic tracer, based on the assumption that its inventory is dominated by the mineralogically-bound component. Given Ti's overall refractory geochemical nature and that it is the 9th most abundant element in the crust, Ti offers several advantages for such use. However, there are suggestions in various literatures (deep-sea carbonates, coastal/estuarine waters and porewaters, and the few extant open ocean data) that Ti may have a quantitatively significant labile behavior that challenges the assumption of its lithogenic exclusivity. We report on a new technique developed to measure dissolved Ti in open ocean seawater. We will present data from SAFe and GEOTRACES intercalibration standards, as well as from complete depth profiles along the US Atlantic GEOTRACES sections sampled in 2010 and 2011. Following work of Biller et al. (2012, Mar. Chem., 130, 12-), preconcentration in our method is achieved via the NOBIAS-chelate PA1 resin of Sohrin et al. (2008, Anal. Chem., 80, 6267-). We achieve a 12-fold concentration from 60 ml of seawater, and samples are analyzed in triplicate. Samples are UV-oxidized prior to column treatment. We have quantified dissolved Ti both by Isotope Dilution quadrupole ICP-MS (ID-ICP-MS) and also by linear calibrations to Ti-free seawaters spiked with variable Ultra High Purity Ti to mimic natural range of abundances. We achieve a total procedural blank of 10 pM, with a detection limit of 6 pM. Ongoing improvements are oriented towards a smaller initial volume of seawater sample. Our results of intercalibration standards S1, D2, GS, and GD agree well with those generated by Croot (2011, Anal. Chem., 83, 6395-) using cathodic stripping voltammetry. We also have analyzed GSP, D1, and NASS-6. Of particular interest is intercalibration standard GD, taken from 2000 m at the BATS location for which Orians et al. (1990, Nature, 348, 322-) have published the only extant data for dissolved Ti in the open Atlantic. Croot's values and our values both agree well with Orians' original analyses, which not only confirms our respective analytical approaches but also suggests that the GEOTRACES rosette system, small parts of which contain Ti, does not contaminate seawater samples for Ti. We also present data from the 2011 GEOTRACES station taken at BATS in the western Atlantic and at Station 11 from the 2010 GEOTRACES transect in the eastern Atlantic. Our profile to 2000 m (= 213 pM) is similar to that of Orians et al. (1990) to the same depth, but extends deeper to 3597 m. Unlike the deep Pacific profile of Orians et al. (1990) from Station PAPA, which extends to 3860 m and reaches a maximum of 263 pM at that depth, our BATS profile is essentially invariant with depth below 2000 m. We observe a similar deepwater distribution at Station 11, which shows an increase from 60 pM near the surface to a maximum of 180 pM at 700 m, followed perhaps by a slight decrease to 130 pM at 3300 m depth.

  9. Dissolved oxygen stratification in two micro-tidal partially-mixed estuaries

    E-print Network

    Mallin, Michael

    Dissolved oxygen stratification in two micro-tidal partially-mixed estuaries Jing Lin a,*, Lian Xie online 21 August 2006 Abstract The controlling physical factors for vertical oxygen stratification that vertical stratification of dissolved oxygen (DO) concentration can be explained by the extended Hansen

  10. Flowsheet modifications for dissolution of sand, slag, and crucible residues in the F-canyon dissolvers

    SciTech Connect

    Rudisill, T.S.; Karraker, D.G.; Graham, F.R.

    1997-12-01

    An initial flowsheet for the dissolution of sand, slag, and crucible (SS{ampersand}C) was developed for the F- Canyon dissolvers as an alternative to dissolution in FB-Line. In that flowsheet, the sand fines were separated from the slag chunks and crucible fragments. Those two SS{ampersand}C streams were packaged separately in mild-steel cans for dissolution in the 6.4D dissolver. Nuclear safety constraints limited the dissolver charge to approximately 350 grams of plutonium in two of the three wells of the dissolver insert and required 0.23M (molar) boron as a soluble neutron poison in the 9.3M nitric acid/0.013M fluoride dissolver solution. During the first dissolution of SS{ampersand}C fines, it became apparent that a significant amount of the plutonium charged to the 6.4D dissolver did not dissolve in the time predicted by previous laboratory experiments. The extended dissolution time was attributed to fluoride complexation by boron. An extensive research and development (R{ampersand}D) program was initiated to investigate the dissolution chemistry and the physical configuration of the dissolver insert to understand what flowsheet modifications were needed to achieve a viable dissolution process.

  11. Student Misconceptions in Writing Balanced Equations for Dissolving Ionic Compounds in Water

    ERIC Educational Resources Information Center

    Naah, Basil M.; Sanger, Michael J.

    2012-01-01

    The goal of this study was to identify student misconceptions and difficulties in writing symbolic-level balanced equations for dissolving ionic compounds in water. A sample of 105 college students were asked to provide balanced equations for dissolving four ionic compounds in water. Another 37 college students participated in semi-structured…

  12. EFFECT OF MECHANICAL POND CIRCULATION ON DISSOLVED OXYGEN AND TEMPERATURE PROFILES IN CHANNEL CATFISH PONDS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Phytoplankton are the primary producers and consumers of dissolved oxygen in earthen channel catfish (Ictalurus punctatus) production ponds. In a pond with a dense plankton bloom, dissolved oxygen (DO) concentration can become supersaturated during daylight hours and fall to 10% of saturation or les...

  13. Microbial and photochemical reactivity of fluorescent dissolved organic matter in a coastal upwelling system

    Microsoft Academic Search

    Eduardo Cabello

    We observed significant changes in the dissolved oxygen content and the fluorescence of humic substances and dissolved aromatic amino acids after 24 h light and dark incubations in the coastal upwelling system of the Rõ´a de Vigo under a wide variety of meteorologic and oceanographic conditions. Respiration rates were inversely correlated with the net production of humic fluorescence in the

  14. Impact of high Saharan dust inputs on dissolved iron concentrations in the Mediterranean Sea

    E-print Network

    Guieu, Cécile

    Impact of high Saharan dust inputs on dissolved iron concentrations in the Mediterranean Sea C) in the Mediterranean Sea, dissolved iron concentrations in seawater and iron and aluminium concentrations in aerosols of Saharan origin on the iron cycle in the Mediterranean Sea. INDEX TERMS: 1065 Geochemistry: Trace elements

  15. A screen-printed amperometric dissolved oxygen sensor utilising an immobilised electrolyte gel and membrane

    Microsoft Academic Search

    Wendy Glasspool; John Atkinson

    1998-01-01

    An amperometric dissolved oxygen sensor based on potentiostatic operation has been designed and fabricated using thick film technology. Calibration of the sensor has shown a strong linear relationship with dissolved oxygen concentration. The devices have been bulk tested for long-term stability and good device to device repeatability has been observed within the batch. Results indicate that a repeatable response to

  16. A composite sol–gel\\/fluoropolymer matrix for dissolved oxygen optical sensing

    Microsoft Academic Search

    R. N. Gillanders; M. C. Tedford; P. J. Crilly; R. T. Bailey

    2004-01-01

    A thin film dissolved oxygen optical sensor was fabricated by encapsulating the phosphorescent dye erythrosin B in a sol–gel\\/fluoropolymer composite matrix. Strong phosphorescence, which was efficiently quenched by dissolved oxygen, was observed. The sensor was stable, optically transparent, resistant to contamination, with good mechanical properties. Fast response, coupled with good sensitivity and resistance to leaching, were also exhibited by this

  17. A procedure for measuring the metrological performance of a dissolved oxygen sensor

    Microsoft Academic Search

    A. K. Rodionov

    2009-01-01

    A procedure for measuring the linearity of a dissolved oxygen sensor is proposed and substantiated mathematically. The application\\u000a of the proposed procedure is illustrated by the results from an experimental study of a serially produced analyzer of dissolved\\u000a oxygen.

  18. Miniature dissolved oxygen and turbulence optical sensor for river and coastal environmental applications

    Microsoft Academic Search

    Edward M. Carapezza; Gabrial Lombardi; Jerry Butman; Ivar Babb

    2009-01-01

    This paper describes an innovative miniature optical sensor for predicting dissolved oxygen concentrations and measuring turbulence in river and littoral water columns. The dissolved oxygen and turbulence sensor consists of a single-frequency laser transmitter and a photodetector on which the scattered light from the turbulent water at the base of a dam or spillway is coherently mixed with a sample

  19. Research on dissolved oxygen classification based-on image processing and neural network

    Microsoft Academic Search

    Liu Liping; Yu Naigong; Sun Jinsheng

    2009-01-01

    Dissolved Oxygen (DO) is one of the most important parameters describing biochemical process in wastewater treatment. It is usually measured with dissolved oxygen meters, and currently galvanic and polarographic electrodes are the predominant methods. Expensive, membrane surface inactivation, and especially need of cleaning and calibrating very frequently are common disadvantages of electrode-type measuring sensors. In our work, a novel method

  20. Needle-type dissolved oxygen microelectrode array sensors for in situ measurements

    Microsoft Academic Search

    Jin-Hwan Lee; Tae-Sun Lim; Youngwoo Seo; Paul L. Bishop; Ian Papautsky

    2007-01-01

    Dissolved oxygen is a critical indicator in a variety of biomedical and environmental processes. This work describes the development of a new needle-type microelectrode array (MEA) sensor for in situ measurements of dissolved oxygen (DO) using microfabrication technologies. A dynamic etching technique was used to fabricate 10mm long sensor probes and sharpen them to micrometer dimensions. The sensors utilized a

  1. UNDERSTANDING AND MANAGING RISKS POSED BY BRINES CONTAINING DISSOLVED CARBON DIOXIDE

    EPA Science Inventory

    Geologic disposal of supercritical carbon dioxide in saline aquifers and depleted oil and gas fields will cause large volumes of brine to become saturated with dissolved CO2 at concentrations of 50 g/l or more.  As CO2 dissolves in brine, the brine de...

  2. Seasonal growth in Laminaria longicruris : Relations with dissolved inorganic nutrients and internal reserves of nitrogen

    Microsoft Academic Search

    A. R. O. Chapman; J. S. Craigie

    1977-01-01

    Observations have been made on seasonal fluctuations in dissolved inorganic nutrients, internal reserves of nitrogen and growth rates in Laminaria longicruris. The onset of winter growth in shallow-water stations (6 and 9 m) correlated well with improved dissolved nitrate conditions in the sea. During the winter, reserves of NO3-were accumulated by the plants and reached maximum values of 150 µmoles

  3. The river Mesta case study: A qualitative model of dissolved oxygen in aquatic ecosystems

    Microsoft Academic Search

    Elena Nakova; Bert Bredeweg; Paulo Salles; Yordan Uzunov

    2009-01-01

    The dynamics of the dissolved oxygen in water bodies is the result of complex interactions involving physical and biological processes. Understanding how the balance of these influences determines the amount of oxygen available for living organisms is a key factor to interpret the water body conditions, and eventually to use dissolved oxygen as an indicator of the water quality. In

  4. Modeling the seasonal autochthonous sources of dissolved organic carbon and nitrogen in the upper Chesapeake Bay

    Microsoft Academic Search

    David P. Keller; Raleigh R. Hood

    2011-01-01

    In this paper we investigate the seasonal autochthonous sources of dissolved organic carbon (DOC) and nitrogen (DON) in the euphotic zone at a station in the upper Chesapeake Bay using a new mass-based ecosystem model. Important features of the model are: (1) carbon and nitrogen are incorporated by means of a set of fixed and varying C:N ratios; (2) dissolved

  5. Spatial and temporal characterisations of the degradation of dissolved humic substances in freshwater lake

    Microsoft Academic Search

    Stefania Mazzuoli; Silvia Focardi; Luca Bracchini; Margherita Falcucci; Steven A. Loiselle; Claudio Rossi

    2005-01-01

    Dissolved organic matter (DOM) is a key component in freshwater ecosystems, strongly influencing the optical, chemical and biological environment. The influence of the organic material on lake water depends on the molecular characteristics of the compounds. In the present study, the spatial distribution of dissolved organic matter and humic concentrations was determined together with the indices for optical colour (a440)

  6. Hydrological controls on dissolved organic carbon during snowmelt in the Snake River near Montezuma, Colorado

    Microsoft Academic Search

    G. M. Hornberger; K. E. Bencala; D. M. McKnight

    1994-01-01

    A quantitative understanding of the factors controlling the variation of dissolved organic carbon (DOC) in headwater streams is of scientific concern for at least two reasons. First, quantifying the overall carbon budgets of lotic systems is needed for a fundamental understanding of these systems. Second, DOC interacts strongly with other dissolved substances (heavy metals in particular) and plays an important

  7. Automatic photocatalytic method for the determination of dissolved organic carbon (DOC) in natural waters

    Microsoft Academic Search

    M. I. Abdullah; E. Eek

    1996-01-01

    An automatic method for the determination of dissolved organic carbon in natural waters is described. The method relies on the catalytic oxidation of dissolved organic matter to CO2 by UV radiation and using a titanium dioxide semiconductor as a catalyst. Several compounds including urea and fulvic acid were mineralised completely. Compared with direct photolysis, the semiconductor catalytic photolysis gave consistently

  8. EFFECTS OF LOW DISSOLVED OXYGEN ON SURVIVAL AND REPRODUCTION OF DAPHNIA, HYALELLA, AND GAMMARUS

    EPA Science Inventory

    Daphnia magna, Daphnia pulex, Hyalella azteca, and Gammarus lacustris were exposed to low dissolved oxygen concentrations in the laboratory. Acute and chronic exposures were conducted to develop data for use in the EPA Water Quality Criteria document for dissolved oxygen. . magna...

  9. Dissolved Oxygen Characteristics of Spring Algal Bloom in Xiangxi Bay of Three Gorges Reservoir

    Microsoft Academic Search

    Huajun Luo; Defu Liu; Daobin Ji; Yingping Huang

    2010-01-01

    Dissolved oxygen characteristics of spring algal bloom in Xiangxi Bay of Three Gorges Reservoir were studied. In surveys, 12 stations have been investigated and 132 samples were collected weekly from February 24 to May 10 in 2008. Chlorophyll a, pH and water temperature could be the significant influence factors to dissolved oxygen in spring algal bloom by using stepwise multiple

  10. STREAM PRODUCTIVITY ANALYSIS WITH DORM (DISSOLVED OXYGEN ROUTING MODEL) - 3: PRODUCTIVITY OF EXPERIMENTAL STREAMS

    EPA Science Inventory

    Thirty-two two-station diel dissolved oxygen surveys were made in the experimental streams of the U.S. EPA Monticello Ecological Research Station. The data were analyzed by a numerical Dissolved Oxygen Routing Model (DORM) to determine total community respiratory and photosynthet...

  11. Bioavailable and biodegradable dissolved organic nitrogen in activated sludge and trickling filter wastewater treatment plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A study was carried out to understand the fate of biodegradable dissolved organic nitrogen (BDON) and bioavailable dissolved organic nitrogen (ABDON) along the treatment trains of a wastewater treatment facility (WWTF) equipped with an activated sludge (AS) system and a WWTF equipped with a two-stag...

  12. The speciation of dissolved copper, cadmium and zinc in Manila Bay, Philippines

    Microsoft Academic Search

    I. B. Velasquez; G. S. Jacinto; F. S. Valera

    2002-01-01

    At present, there is a very limited information on the levels and distribution of dissolved metals in Manila Bay. In this study, the horizontal and vertical distribution of operationally defined species (labile, bound and total) of dissolved copper (Cu), cadmium (Cd) and zinc (Zn) were determined using differential pulse anodic and cathodic stripping voltammetry in water samples obtained from 18

  13. Chromophoric Dissolved Organic Matter (CDOM) In Rainwater, Southeastern North Carolina, USA

    Microsoft Academic Search

    Robert J. Kieber; Robert F. Whitehead; Seth N. Reid; Joan D. Willey; Pamela J. Seaton

    2006-01-01

    The abundance and optical characteristics of dissolved organic matter (DOM) were determined in 120 rain samples collected in Wilmington, North Carolina, USA, between February 21, 2002 and August 11, 2003. All rainwater samples contained chromophoric dissolved organic matter (CDOM) as well as fluorescent compounds. The absorbance spectra of CDOM in the samples decreased exponentially with wavelength with little or no

  14. Modeling the spectral shape of absorption by chromophoric dissolved organic matter

    E-print Network

    Boss, Emmanuel S.

    Modeling the spectral shape of absorption by chromophoric dissolved organic matter Michael S of its application and interpretation in describing absorption by chromophoric dissolved organic matter collected with an ac9 in-situ spectrophotometer from around the coastal United States were used

  15. Precipitation of dissolved sulphide in pulp and paper mill wastewater by electrocoagulation

    Microsoft Academic Search

    Mikko Vepsäläinen; Jukka Selin; Pekka Rantala; Martti Pulliainen; Heikki Särkkä; Kaisa Kuhmonen; Amit Bhatnagar; Mika Sillanpää

    2011-01-01

    The precipitation of dissolved sulphide ions by electrocoagulation was studied at laboratory scale using pulp and paper mill wastewaters. Concentrations of dissolved organic carbon and phosphorus were analysed before and after the electrocoagulation process to examine the suitability of the process for treatment of sulphide odour from pulp and paper mill wastewater. The electrochemical cell used in this study was

  16. DISSOLVED ORGANIC CARBON (DOC) CONCENTRATIONS IN SMALL STREAMS OF THE GEORGIA PIEDMONT

    EPA Science Inventory

    Dissolved organic matter (DOM) supports microbial activity and contributes to transport of N and P in streams. We have studied the impact of land uses on dissolved organic carbon (DOC) concentrations in 17 Georgia Piedmont headwater streams since January 2001. We classified the w...

  17. Characterization of six phosphate-dissolving bacteria isolated from rhizospheric soils in Mali

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Maize rhizospheric soils in Mali were analyzed for concentrations of microorganisms capable of dissolving phosphate rock and producing plant growth substances. Six bacteria were isolated and found to have the capacity to dissolve /solubilize the Tilemsi phosphate rock (TPR) available in Mali by prod...

  18. Forecasting dissolved gases content in power transformer oil based on support vector machine with genetic algorithm

    Microsoft Academic Search

    Sheng-Wei Fei; Yu Sun

    2008-01-01

    Forecasting of dissolved gases content in power transformer oil is very significant to detect incipient failures of transformer early and ensure hassle free operation of entire power system. Forecasting of dissolved gases content in power transformer oil is a complicated problem due to its nonlinearity and the small quantity of training data. Support vector machine (SVM) has been successfully employed

  19. Dissolved organic matter in the ocean: recalcitrant or simply too diverse for bio-degradation?

    Microsoft Academic Search

    Gerhard Kattner; Boris P. Koch

    2010-01-01

    The amount of carbon in the dissolved organic matter (DOM) pool in the ocean is estimated to be 700 Pg C, whereas the particulate marine organic carbon accounts only for about 30 Pg C. Dissolved organic carbon (DOC) is almost as much as the amount of carbon in atmospheric CO2 (~800 Pg) or terrestrial biomass (~610 Pg). The majority of

  20. Relationships among Nutrients, Chlorophyll-a, and Dissolved Oxygen in Agricultural Streams in Illinois

    E-print Network

    David, Mark B.

    consistently in only two of the five streams. The abundance of filamentous algae explained 64% of the variation understanding of the controls on algae and dissolved O2 in agricultural streams of Illinois is needed to aid to limit filamentous algal blooms. ADEQUATE dissolved O2 is vital for the survival of aquatic organisms

  1. The distribution of dissolved and particulate mercury in three Siberian estuaries and adjacent Arctic coastal waters

    Microsoft Academic Search

    M. Coquery; D. Cossa; J. M. Martin

    1995-01-01

    Dissolved and particulate mercury distributions were determined in the three largest Siberian rivers and in adjacent Arctic coastal waters during two cruises. Water samples were collected in the Lena River and its mixing zone in the Laptev Sea in September 1991, and in the Ob and Yenisei Rivers and the adjacent Kara Sea in September 1993. Average total dissolved Hg

  2. FACTORS INFLUENCING PHOTOREACTIONS OF DISSOLVED ORGANIC MATTER IN A COASTAL RIVER OF THE SOUTHEASTERN UNITED STATES

    EPA Science Inventory

    Photoreactions of dissolved organic matter can affect the oxidizing capacity, nutrient dynamics, trace gas exchange, and color of surface waters. This study focuses on factors that affect the photoreactions of the colored dissolved organic matter (CDOM) in the Satilla River, a co...

  3. Response of Dissolved Organic Matter to Warming and Nitrogen Addition

    NASA Astrophysics Data System (ADS)

    Choi, J. H.; Nguyen, H.

    2014-12-01

    Dissolved Organic Matter (DOM) is a ubiquitous mixture of soluble organic components. Since DOM is produced from the terrestrial leachate of various soil types, soil may influence the chemistry and biology of freshwater through the input of leachate and run-off. The increased temperature by climate change could dramatically change the DOM characteristics of soils through enhanced decomposition rate and losses of carbon from soil organic matter. In addition, the increase in the N-deposition affects DOM leaching from soils by changing the carbon cycling and decomposition rate of soil decay. In this study, we conducted growth chamber experiments using two types of soil (wetland and forest) under the conditions of temperature increase and N-deposition in order to investigate how warming and nitrogen addition influence the characteristics of the DOM leaching from different soil types. This leachate controls the quantity and quality of DOM in surface water systems. After 10 months of incubation, the dissolved organic carbon (DOC) concentrations decreased for almost samples in the range of 7.6 to 87.3% (ANOVA, p<0.05). The specific UV absorption (SUVA) values also decreased for almost samples after the first 3 months and then increased gradually afterward in range of 3.3 to 108.4%. Both time and the interaction between time and the temperature had the statistically significant effects on the SUVA values (MANOVA, p<0.05). Humification index (HIX) showed the significant increase trends during the duration of incubation and temperature for almost the samples (ANOVA, p<0.05). Higher decreases in the DOC values and increases in HIX were observed at higher temperatures, whereas the opposite trend was observed for samples with N-addition. The PARAFAC results showed that three fluorescence components: terrestrial humic (C1), microbial humic-like (C2), and protein-like (C3), constituted the fluorescence matrices of soil samples. During the experiment, labile DOM from the soils was consumed and transformed into resistant aromatic carbon structures and less biodegradable components via microbial processes. Both time and the temperature presented the statistically significant effects on DOM characteristics of soil samples while the N-addition exhibited the insignificant difference among the samples.

  4. Dissolved Mn Speciation and Ligand Characteristics in a Coastal Waterway

    NASA Astrophysics Data System (ADS)

    Oldham, V.; Jensen, L.; Luther, G. W., III

    2014-12-01

    Soluble manganese speciation (Mn(II) and Mn(III); 0.2 ?m filtered) was measured along a salinity gradient in the Broadkill River, a coastal waterway bordered by wetlands and salt marshes in Delaware. We modified an established method of porphyrin (T-4(CP)P) addition, by incorporating a heating step and coupling a 100-cm cell to a UV/Vis detector, to achieve a 4.0 nM sample DL. Surface waters were collected from June to August, 2014 and total dissolved Mn (0.23 - 1.92 ?M) first increased then decreased along the salinity gradient (31 ppt to freshwater). However, Mn speciation was highly variable; Mn(III) made up 0-49 % of the total dissolved Mn, where the highest Mn(III) values occurred at sites with high salt-marsh runoff. Mn(III) was not recoverable without the addition of a strong reducing agent, indicating that little or no weak ligand was present, and that a strong ligand was responsible for complexing Mn(III). An assessment of potential strong ligand character was made by precipitating humic matter, by acidifying subsamples to pH<1.5, then 100 ?M Mn(III)-pyrophosphate was added to acidified supernatant samples and non-acidified samples. In non-acidified samples, the Mn(III)-pyrophosphate peak at 484 nm rapidly disappeared and was replaced by a broad peak at 400 nm and the resulting sample had a yellow color. Upon the addition of 500 ?M desferrioxamine-B (DFOB) to the same sample, a peak at 310 nm appeared, indicating the formation of Mn(III)-DFOB. In acidified samples, the Mn(III)-pyrophosphate peak did not change. Humic matter, therefore, may be acting as an Mn(III) binding ligand, outcompeting pyrophosphate for Mn(III), however this natural ligand is outcompeted by a large excess of DFOB. The humic matter and increased Mn likely come from the salt marsh runoff during tidal exchange, and we observed that as salinity increased, the amount of humic binding decreased. These results present the first Mn speciation measurements along a salinity gradient in oxygenated waters.

  5. Can mineral precipitation reduce the breakthrough time in dissolving porous medium?

    NASA Astrophysics Data System (ADS)

    Budek, Agnieszka; Szymczak, Piotr

    2015-04-01

    We investigate the chemical erosion of porous media using a 2D network model in which the system is represented as a series of interconnected pipes. We consider a system with two coupled reactions involving dissolution of a solid component and precipitation of dissolution products, which results in the overall change of pore diameters. Importantly, the topology of the network is allowed to change dynamically during the simulation: as the diameters of the eroding pores become comparable with the interpore distances, the pores are joined together, thus changing the interconnections within the network. With this model, we investigate different growth regimes in an evolving porous medium, identifying the mechanisms responsible for the emergence of specific patterns. We study the change of permeability of the system in time. The crucial parameter here is the ratio of dissolution to precipitation reaction rates. Depending on its value, the permeability either increases, decreases or oscillates in time. Finally, we consider practically important problem of finding an optimum reactions rates that give a maximum increase in permeability for a given amount of dissolving reactant. Somewhat paradoxically, we find that precipitation can, for a particular range of parameters, make the dissolution more efficient by focusing it in localized regions.

  6. Interannual variability of primary production and dissolved organic nitrogen storage in the North Pacific Subtropical Gyre

    NASA Astrophysics Data System (ADS)

    Luo, Ya-Wei; Ducklow, Hugh W.; Friedrichs, Marjorie A. M.; Church, Matthew J.; Karl, David M.; Doney, Scott C.

    2012-09-01

    The upper ocean primary production measurements from the Hawaii Ocean Time series (HOT) at Station ALOHA in the North Pacific Subtropical Gyre showed substantial variability over the last two decades. The annual average primary production varied within a limited range over 1991-1998, significantly increased in 1999-2000 and then gradually decreased afterwards. This variability was investigated using a one-dimensional ecosystem model. The long-term HOT observations were used to constrain the model by prescribing physical forcings and lower boundary conditions and optimizing the model parameters against data using data assimilation. The model reproduced the general interannual pattern in the observed primary production, and mesoscale variability in vertical velocity was identified as a major contributing factor to the interannual variability in the simulation. Several strong upwelling events occurred in 1999, which brought up nitrate at rates several times higher than other years and elevated the model primary production. Our model results suggested a hypothesis for the observed interannual variability pattern of primary production at Station ALOHA: Part of the upwelled nitrate input in 1999 was converted to and accumulated as semilabile dissolved organic nitrogen (DON), and subsequent recycling of this semilabile DON supported enhanced primary productivity for the next several years as the semilabile DON perturbation was gradually removed via export.

  7. X-ray absorption spectroscopy as a probe of dissolved polysulfides in lithium sulfur batteries

    NASA Astrophysics Data System (ADS)

    Pascal, Tod; Prendergast, David

    2015-03-01

    There has been enormous interest lately in lithium sulfur batteries, since they have 5 times the theoretical capacity of lithium ion batteries. Large-scale adoption of this technology has been hampered by numerous shortcomings, chiefly the poor utilization of the active cathode material and rapid capacity fading during cycling. Overcoming these limitations requires methods capable of identifying and quantifying the products of the poorly understood electrochemical reactions. One recent advance has been the use of X-ray absorption spectroscopy (XAS), an element-specific probe of the unoccupied energy levels around an excited atom upon absorption of an X-ray photon, to identify the reaction products and intermediates. In this talk, we'll present first principles molecular dynamics and spectral simulations of dissolved lithium polysulfide species, showing how finite temperature dynamics, molecular geometry, molecular charge state and solvent environment conspire to determine the peak positions and intensity of the XAS. We'll present a spectral analysis of the radical (-1e charge) species, and reveal a unique low energy feature that can be used to identify these species from their more common dianion (-2e charge) counterparts.

  8. The optimal dissolved oxygen profile in a nitrifying activated sludge process - comparisons with ammonium feedback control.

    PubMed

    Amand, L; Carlsson, B

    2013-01-01

    Ammonium feedback control is increasingly used to determine the dissolved oxygen (DO) set-point in aerated activated sludge processes for nitrogen removal. This study compares proportional-integral (PI) ammonium feedback control with a DO profile created from a mathematical minimisation of the daily air flow rate. All simulated scenarios are set to reach the same treatment level of ammonium, based on a daily average concentration. The influent includes daily variations only and the model has three aerated zones. Comparisons are made at different plant loads and DO concentrations, and the placement of the ammonium sensor is investigated. The results show that ammonium PI control can achieve the best performance if the DO set-point is limited at a maximum value and with little integral action in the controller. Compared with constant DO control the best-performing ammonium controller can achieve 1-3.5% savings in the air flow rate, while the optimal solution can achieve a 3-7% saving. Energy savings are larger when operating at higher DO concentrations. PMID:23925193

  9. Photobleaching-induced changes in photosensitizing properties of dissolved organic matter.

    PubMed

    Niu, Xi-Zhi; Liu, Chao; Gutierrez, Leo; Croué, Jean-Philippe

    2014-12-01

    Photosensitizing properties of different dissolved organic matter (DOM) were investigated according to their performance in singlet oxygen ((1)O2), triplet state of DOM ((3)DOM*), and hydroxyl radical (·OH) productions. The photobleaching of DOM solutions after irradiation was characterized by fluorescence excitation-emission matrix and UV-Vis spectroscopy. The photosensitizing properties of pre-irradiated DOM solutions were changed in a sunlight simulator. The performance of DOMs in photosensitized degradation of several contaminants was investigated. For a 20 h exposure, the observed degradation rate constant (kobs) of some contaminants decreased as a function of exposure time, and highly depended on the properties of both DOM and contaminant. Degradation of contaminants with lower kobs was more susceptible to DOM photobleaching-induced decrease in kobs. Under the current experimental conditions, the photobleaching-induced decrease of DOM photo-reactivity in contaminant degradation was mainly attributed to indirect phototransformation of DOM caused by the interactions between photo-inductive DOM moieties and photochemically-produced reactive species. Reactive contaminants can inhibit DOM indirect photobleaching by scavenging reactive species, photosensitized degradation of these contaminants exhibited a stable kobs as a result. This is the first study to report DOM photobleaching-induced changes in the simultaneous DOM photosensitized degradation of contaminants and the inhibitory effect of reactive contaminants on DOM photobleaching. PMID:25201337

  10. [Characterizing composition and transformation of dissolved organic matter in subsurface wastewater infiltration system].

    PubMed

    Wang, Li-Jun; Liu, Yu-Zhong; Zhang, Lie-Yu; Xi, Bei-Dou; Xia, Xun-Feng; Liu, Ya-Ru

    2013-08-01

    In the present study, the soil column with radius of 30 cm and height of 200 cm was used to simulate a subsurface wastewater infiltration system. Under the hydraulic loading of 4 cm x d(-1), composition and transformation of dissolved organic matter (DOM) from different depths were analyzed in a subsurface wastewater infiltration system for treatment of septic tank effluent using three-dimensional excitation emission matrix fluorescence spectroscopy (3D-EEM) with regional integration analysis (FRI). The results indicate that: (1) from different depth, the composition of DOM was also different; influent with the depth of 0.5 m was mainly composed of protein-like substances, and that at other depths was mainly composed of humic- and fulvic-like substances. (2) DOM stability gradually increased and part of the nonbiodegradable organic matter can be removed during organic pollutants degradation process. (3) Not only the organic pollutants concentration was reduced effectively, but also the stability of the DOM improved in subsurface wastewater infiltration system. PMID:24159860

  11. Effects of phototransformation of Dissolved Organic Matter on its susceptibility to bacterial mineralization

    NASA Astrophysics Data System (ADS)

    Grzybowski, W.; Kowalczuk, P.

    2009-04-01

    Impact of UV radiation on susceptibility of dissolved organic matter (DOM) to bacterial mineralization was investigated in water bodies of different optical properties. Experimental material consisted of 28 samples of the Vistula River water and 32 samples of water from Bay of Gdansk collected during late spring and early summer. After collection the samples were sterile-filtered and irradiated for 4 h in simulated UV solar radiation. Afterward, the irradiated and control samples were mixed (50:50, v/v) with the "parent" samples filtered through the Whatman GF/C filters. The PC-controlled oxygen electrodes (Clark-type) were used in monitoring bacterial respiration. A conservative estimate of the measurement precision was 5 M O2. Oxygen concentration was measured every hour during the 40h long, concurrent incubations containing irradiated and non-irradiated DOM. There was no negative impact of irradiation on biodegradability of DOM. Increase in bacterial oxygen demand (BOD) was observed in all samples of Vistula River water characterized by higher values of absorption coefficient. The BOD40h increase ranged from 20 to 90 % relative to control samples. Preliminary data from the longer incubations suggest that irradiation of DOM does not enlarge pool of usable compounds but accelerate their biomineralization.

  12. Characteristics and transformations of dissolved organic nitrogen in municipal biological nitrogen removal wastewater treatment plants

    NASA Astrophysics Data System (ADS)

    Huo, Shouliang; Xi, Beidou; Yu, Honglei; Qin, Yanwen; Zan, Fengyu; Zhang, Jingtian

    2013-12-01

    Dissolved organic nitrogen (DON) represents most of the dissolved nitrogen in the effluent of biological nitrogen removal (BNR) wastewater treatment plants (WWTPs). The characteristics of wastewater-derived DON in two different WWTPs were investigated by several different methods. The major removals of DON and biodegradable dissolved organic nitrogen (BDON) along the treatment train were observed in the anaerobic process. Dissolved combined amino acids (DCAA) and dissolved free amino acids (DFAA) in the effluent accounted approximately for less than 4% and 1% of the effluent DON, respectively. Approximately half of wastewater-derived DON was capable of passing through a 1 kDa ultrafilter, and low MW DON cannot effectively be removed by BNR processes. More than 80% of effluent DON was composed of hydrophilic compounds, which stimulate algal growth. The study provided important information for future upgrading of WWTPs or the selection of DON removal systems to meet more demanding nitrogen discharge limits.

  13. An advanced passive diffusion sampler for the determination of dissolved gas concentrations

    NASA Astrophysics Data System (ADS)

    Gardner, P.; Solomon, D. K.

    2009-06-01

    We have designed and tested a passive headspace sampler for the collection of noble gases that allows for the precise calculation of dissolved gas concentrations from measured gas mixing ratios. Gas permeable silicon tubing allows for gas exchange between the headspace in the sampler volume and the dissolved gases in the adjacent water. After reaching equilibrium, the aqueous-phase concentration is related to the headspace concentration by Henry's law. Gas exchange between the water and headspace can be shut off in situ, preserving the total dissolved gas pressure upon retrieval. Gas samples are then sealed in an all metal container, retaining even highly mobile helium. Dissolved noble gas concentrations measured in these diffusion samplers are in good agreement with traditional copper tube aqueous-phase samples. These significantly reduce the laboratory labor in extracting the gases from a water sample and provide a simple and robust method for collecting dissolved gas concentrations in a variety of aqueous environments.

  14. Effects of the lampricide 3-trifluoromethyl-4-nitrophenol on dissolved oxygen in aquatic systems

    USGS Publications Warehouse

    Dawson, V.K.; Johnson, D.A.; Sullivan, J.F.

    1992-01-01

    The effects of the lampricide 3-trifluoromethyl-4-nitrophenol (TFM) on dissolved oxygen and other water- quality characteristics were evaluated in a series of test chambers under selected combinations of water, sediment, TFM, and exposure to sunlight. Concentrations of TFM gradually decreased over time, especially in the presence of sediment and sunlight. The lampricide did not directly cause a reduction in dissolved oxygen concentration, but appeared to inhibit photosynthetic production of oxygen during daylight. Dissolved oxygen concentrations were significantly reduced by the presence of TFM in chambers exposed to sunlight. Concentrations of total ammonia were significantly higher in chambers with sediment than in those without sediment. In chambers that contained river water and were exposed to sunlight, ammonia concentrations were low because of either oxidation by the elevated dissolved oxygen concentrations or the assimilation of nutrients by algae. The observed changes in dissolved oxygen and ammonia because of the presence of TFM were subtle, but statistically significant.

  15. Hidden cycle of dissolved organic carbon in the deep ocean.

    PubMed

    Follett, Christopher L; Repeta, Daniel J; Rothman, Daniel H; Xu, Li; Santinelli, Chiara

    2014-11-25

    Marine dissolved organic carbon (DOC) is a large (660 Pg C) reactive carbon reservoir that mediates the oceanic microbial food web and interacts with climate on both short and long timescales. Carbon isotopic content provides information on the DOC source via ?(13)C and age via ?(14)C. Bulk isotope measurements suggest a microbially sourced DOC reservoir with two distinct components of differing radiocarbon age. However, such measurements cannot determine internal dynamics and fluxes. Here we analyze serial oxidation experiments to quantify the isotopic diversity of DOC at an oligotrophic site in the central Pacific Ocean. Our results show diversity in both stable and radio isotopes at all depths, confirming DOC cycling hidden within bulk analyses. We confirm the presence of isotopically enriched, modern DOC cocycling with an isotopically depleted older fraction in the upper ocean. However, our results show that up to 30% of the deep DOC reservoir is modern and supported by a 1 Pg/y carbon flux, which is 10 times higher than inferred from bulk isotope measurements. Isotopically depleted material turns over at an apparent time scale of 30,000 y, which is far slower than indicated by bulk isotope measurements. These results are consistent with global DOC measurements and explain both the fluctuations in deep DOC concentration and the anomalous radiocarbon values of DOC in the Southern Ocean. Collectively these results provide an unprecedented view of the ways in which DOC moves through the marine carbon cycle. PMID:25385632

  16. COLLEGE STUDENTS’ INTEREST IN TRYING DISSOLVABLE TOBACCO PRODUCTS

    PubMed Central

    Wolfson, Mark; Pockey, Jessica R.; Reboussin, Beth A.; Sutfin, Erin L.; Egan, Kathleen L.; Wagoner, Kimberly G.; Spangler, John G.

    2014-01-01

    Background Dissolvable tobacco products (DTPs) have been introduced into test markets in the U.S. We sought to gauge level of interest in trying these products and correlates of interest among potential consumers. Methods A web-based survey of freshman at 11 universities in North Carolina (NC) and Virginia (VA) was conducted in fall 2010. Multivariable logistic regression analyses were used to identify correlates of students’ likelihood to try DTPs. Results Weighted prevalence of likelihood to try DTPs was 3.7%. Significant correlates of likelihood to try included male gender, current cigarette smoking, current snus use, sensation seeking, lifetime illicit drug use, and perceived health risk of using DTPs. Among current smokers, current snus use, current use of chewing tobacco, and considering quitting smoking were associated with likelihood to try DTPs. Conclusions While overall interest in trying these products was low, current users of cigarettes and snus were much more likely than others in trying a free sample. Some current smokers may consider DTPs to be an aid to smoking cessation, although the population-level impact of introducing these products is unknown. PMID:24309296

  17. The Oxidant Budget of Dissolved Organic Carbon Driven Isotope Excursions

    NASA Astrophysics Data System (ADS)

    Bristow, T. F.; Kennedy, M. J.

    2008-12-01

    Negative carbon isotope values, falling below the mantle average of about -5 per mil, in carbonate phases of Ediacaran age sedimentary rocks are widely regarded as reflecting negative excursions in the carbon isotopic composition of seawater lasting millions of years. These isotopic signals form the basis of chemostratigraphic correlations between Ediacaran aged sections in different parts of the world, and have been used to track the oxidation of the biosphere. However, these isotopic values are difficult to accommodate within limits prescribed by the current understanding of the carbon cycle, and a hypothetical Precambrian ocean dissolved organic carbon (DOC) pool 100 to 1000 times the size of the modern provides a potential source of depleted carbon not considered in Phanerozoic carbon cycle budgets. We present box model results that show the remineralization of such a DOC pool to drive an isotope excursion of the magnitude observed in the geological record exhausts global budgets of free oxygen and sulfate in 800 k.y. These results are incompatible with the estimated duration of late Ediacaran isotope excursions of more than 10 m.y., as well as geochemical and biological indicators that oceanic sulfate and oxygen levels were maintained or even increased at the same time. Therefore the carbon isotope record is probably not a useful tool for monitoring oxygen levels in the atmosphere and ocean. Covariation between the carbon and oxygen isotope records is often observed during negative excursions and is indicative of local processes or diagenetic overprinting.

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

    NASA Technical Reports Server (NTRS)

    Mannino, Antonio; Harvey, H. Rodger

    2003-01-01

    Black carbon (BC) in ultrafiltered high-molecular-weight DOM (UDOM) was measured in surface waters of Delaware Bay, Chesapeake Bay and the adjacent Atlantic Ocean (USA) to ascertain the importance of riverine and estuarine DOM as a source of BC to the ocean. BC comprised 5-72% of UDOM-C (27+/-l7%) and on average 8.9+/-6.5% of dissolved organic carbon (DOC) with higher values in the turbid region of the Delaware Estuary and lower yields in the river and coastal ocean. The spatial and seasonal distributions of BC along the salinity gradient of Delaware Bay suggest that the higher levels of BC in surface water UDOM originated from localized sources, possibly from atmospheric deposition or released from resuspended sediments. Black carbon comprised 4 to 7% of the DOC in the coastal Atlantic Ocean, revealing that river-estuary systems are important exporters of colloidal BC to the ocean. The annual flux of BC from Delaware Bay UDOM to the Atlantic Ocean was estimated at 2.4x10(exp 10) g BC yr(exp -1). The global river flux of BC through DOM to the ocean could be on the order of 5.5x1O(exp 12)g BC yr (exp -1). These results support the hypothesis that the DOC pool is the intermediate reservoir in which BC ages prior to sedimentary deposition.

  19. Field observation of diurnal dissolved oxygen fluctuations in shallow groundwater.

    PubMed

    Schilling, Keith E; Jacobson, Peter

    2015-05-01

    Dissolved oxygen (DO) concentrations influence many biogeochemical processes in groundwater systems but studies of temporal variability in DO are lacking. In this study, we used an optical DO probe to measure rapid changes in concentration due to plant-groundwater interaction at an alluvial aquifer field site in Iowa. Diurnal DO concentrations were observed during mid- to late-summer when soil conditions were dry, fluctuating approximately 0.2 to 0.3 mg/L on a daily basis. DO fluctuations in groundwater were out-of-phase with diurnal water table fluctuations, increasing during the day and decreasing at night. DO consumption at night is likely due to increased soil autotrophic and heterotrophic respiration linked with patterns of carbon supply derived from daytime photosynthetic activity, and consistent with available literature on diurnal soil respiration patterns. Although more work is needed to quantify specific processes, our results indicate the potential usefulness of the new optical DO technology to reveal insights regarding many ecohydrological processes. PMID:24841899

  20. The distribution of dissolved iron in the West Atlantic Ocean.

    PubMed

    Rijkenberg, Micha J A; Middag, Rob; Laan, Patrick; Gerringa, Loes J A; van Aken, Hendrik M; Schoemann, Véronique; de Jong, Jeroen T M; de Baar, Hein J W

    2014-01-01

    Iron (Fe) is an essential trace element for marine life. Extremely low Fe concentrations limit primary production and nitrogen fixation in large parts of the oceans and consequently influence ocean ecosystem functioning. The importance of Fe for ocean ecosystems makes Fe one of the core chemical trace elements in the international GEOTRACES program. Despite the recognized importance of Fe, our present knowledge of its supply and biogeochemical cycle has been limited by mostly fragmentary datasets. Here, we present highly accurate dissolved Fe (DFe) values measured at an unprecedented high intensity (1407 samples) along the longest full ocean depth transect (17,500 kilometers) covering the entire western Atlantic Ocean. DFe measurements along this transect unveiled details about the supply and cycling of Fe. External sources of Fe identified included off-shelf and river supply, hydrothermal vents and aeolian dust. Nevertheless, vertical processes such as the recycling of Fe resulting from the remineralization of sinking organic matter and the removal of Fe by scavenging still dominated the distribution of DFe. In the northern West Atlantic Ocean, Fe recycling and lateral transport from the eastern tropical North Atlantic Oxygen Minimum Zone (OMZ) dominated the DFe-distribution. Finally, our measurements showed that the North Atlantic Deep Water (NADW), the major driver of the so-called ocean conveyor belt, contains excess DFe relative to phosphate after full biological utilization and is therefore an important source of Fe for biological production in the global ocean. PMID:24978190

  1. Liquid contents verification for explosives, chemical agents, and dissolved narcotics

    NASA Astrophysics Data System (ADS)

    Kumar, Sankaran; McMichael, W. Casey; Magnuson, Erik E.; Lee, Young K.; Moeller, Charles R.; Czipott, Peter V.; Rayner, Timothy J.; Newman, David E.; Wroblewski, Dariusz

    2001-02-01

    An increasingly important need today is to guard against terrorist attacks at key locations such as airports and public buildings. Liquid explosives can avoid detection at security checkpoints by being concealed as beverages or other benign liquids. Magnetic resonance (MR) offers a safe, non-invasive technology for probing and classifying the liquid contents inside sealed non-metallic containers or packages. Quantum Magnetics has developed a Liquid Explosives Screening System or `Bottle Scanner' to screen for liquid explosives and flammables, described at an earlier SPIE conference in 1996. Since then, the Bottle Scanner's performance has been significantly improved by the incorporation of neural network-based liquid classification. Recently we have shown that the incorporation of additional discrimination parameters can further enhance liquid classification. In addition to screening for explosives and flammables, the Bottle Scanner can be effective against chemical agents, many of which contain fluorine or phosphorous, both of which have MR signatures. Finally, we have evidence that the Bottle Scanner may also be able to detect narcotics dissolved in beverages, one of the methods used to smuggle narcotics across international borders. The development of the Bottle Scanner has been funded by the Federal Aviation Administration.

  2. Hidden cycle of dissolved organic carbon in the deep ocean

    PubMed Central

    Follett, Christopher L.; Repeta, Daniel J.; Rothman, Daniel H.; Xu, Li; Santinelli, Chiara

    2014-01-01

    Marine dissolved organic carbon (DOC) is a large (660 Pg C) reactive carbon reservoir that mediates the oceanic microbial food web and interacts with climate on both short and long timescales. Carbon isotopic content provides information on the DOC source via ?13C and age via ?14C. Bulk isotope measurements suggest a microbially sourced DOC reservoir with two distinct components of differing radiocarbon age. However, such measurements cannot determine internal dynamics and fluxes. Here we analyze serial oxidation experiments to quantify the isotopic diversity of DOC at an oligotrophic site in the central Pacific Ocean. Our results show diversity in both stable and radio isotopes at all depths, confirming DOC cycling hidden within bulk analyses. We confirm the presence of isotopically enriched, modern DOC cocycling with an isotopically depleted older fraction in the upper ocean. However, our results show that up to 30% of the deep DOC reservoir is modern and supported by a 1 Pg/y carbon flux, which is 10 times higher than inferred from bulk isotope measurements. Isotopically depleted material turns over at an apparent time scale of 30,000 y, which is far slower than indicated by bulk isotope measurements. These results are consistent with global DOC measurements and explain both the fluctuations in deep DOC concentration and the anomalous radiocarbon values of DOC in the Southern Ocean. Collectively these results provide an unprecedented view of the ways in which DOC moves through the marine carbon cycle. PMID:25385632

  3. The measurement of dissolved and gaseous carbon dioxide concentration

    NASA Astrophysics Data System (ADS)

    Zosel, J.; Oelßner, W.; Decker, M.; Gerlach, G.; Guth, U.

    2011-07-01

    In this review the basic principles of carbon dioxide sensors and their manifold applications in environmental control, biotechnology, biology, medicine and food industry are reported. Electrochemical CO2 sensors based on the Severinghaus principle and solid electrolyte sensors operating at high temperatures have been manufactured and widely applied already for a long time. Besides these, nowadays infrared, non-dispersive infrared and acoustic CO2 sensors, which use physical measuring methods, are being increasingly used in some fields of application. The advantages and drawbacks of the different sensor technologies are outlined. Electrochemical sensors for the CO2 measurement in aqueous media are pointed out in more detail because of their simple setup and the resulting low costs. A detailed knowledge of the basic detection principles and the windows for their applications is necessary to find an appropriate decision on the technology to be applied for measuring dissolved CO2. In particular the pH value and the composition of the analyte matrix exert important influence on the results of the measurements.

  4. Latitudinal Gradients in Degradation of Marine Dissolved Organic Carbon

    PubMed Central

    Arnosti, Carol; Steen, Andrew D.; Ziervogel, Kai; Ghobrial, Sherif; Jeffrey, Wade H.

    2011-01-01

    Heterotrophic microbial communities cycle nearly half of net primary productivity in the ocean, and play a particularly important role in transformations of dissolved organic carbon (DOC). The specific means by which these communities mediate the transformations of organic carbon are largely unknown, since the vast majority of marine bacteria have not been isolated in culture, and most measurements of DOC degradation rates have focused on uptake and metabolism of either bulk DOC or of simple model compounds (e.g. specific amino acids or sugars). Genomic investigations provide information about the potential capabilities of organisms and communities but not the extent to which such potential is expressed. We tested directly the capabilities of heterotrophic microbial communities in surface ocean waters at 32 stations spanning latitudes from 76°S to 79°N to hydrolyze a range of high molecular weight organic substrates and thereby initiate organic matter degradation. These data demonstrate the existence of a latitudinal gradient in the range of complex substrates available to heterotrophic microbial communities, paralleling the global gradient in bacterial species richness. As changing climate increasingly affects the marine environment, changes in the spectrum of substrates accessible by microbial communities may lead to shifts in the location and rate at which marine DOC is respired. Since the inventory of DOC in the ocean is comparable in magnitude to the atmospheric CO2 reservoir, such a change could profoundly affect the global carbon cycle. PMID:22216139

  5. The Distribution of Dissolved Iron in the West Atlantic Ocean

    PubMed Central

    Rijkenberg, Micha J. A.; Middag, Rob; Laan, Patrick; Gerringa, Loes J. A.; van Aken, Hendrik M.; Schoemann, Véronique; de Jong, Jeroen T. M.; de Baar, Hein J. W.

    2014-01-01

    Iron (Fe) is an essential trace element for marine life. Extremely low Fe concentrations limit primary production and nitrogen fixation in large parts of the oceans and consequently influence ocean ecosystem functioning. The importance of Fe for ocean ecosystems makes Fe one of the core chemical trace elements in the international GEOTRACES program. Despite the recognized importance of Fe, our present knowledge of its supply and biogeochemical cycle has been limited by mostly fragmentary datasets. Here, we present highly accurate dissolved Fe (DFe) values measured at an unprecedented high intensity (1407 samples) along the longest full ocean depth transect (17500 kilometers) covering the entire western Atlantic Ocean. DFe measurements along this transect unveiled details about the supply and cycling of Fe. External sources of Fe identified included off-shelf and river supply, hydrothermal vents and aeolian dust. Nevertheless, vertical processes such as the recycling of Fe resulting from the remineralization of sinking organic matter and the removal of Fe by scavenging still dominated the distribution of DFe. In the northern West Atlantic Ocean, Fe recycling and lateral transport from the eastern tropical North Atlantic Oxygen Minimum Zone (OMZ) dominated the DFe-distribution. Finally, our measurements showed that the North Atlantic Deep Water (NADW), the major driver of the so-called ocean conveyor belt, contains excess DFe relative to phosphate after full biological utilization and is therefore an important source of Fe for biological production in the global ocean. PMID:24978190

  6. The behavior of dissolved inorganic selenium in the Bohai Sea

    NASA Astrophysics Data System (ADS)

    Yao, Qing-Zheng; Zhang, Jing

    2005-04-01

    Two cruises of "R/V Dong Fang Hong 2" were carried out in September 1998 and May 1999, respectively, to understand the behavior of selenium in the Bohai Sea. Selenium species (dissolved inorganic selenium, selenite) are determined by HG-AFS for 30 grid stations. Selenium concentrations display short-term variability and seasonal change in the Bohai Sea, with higher levels in shallow coastal waters than in the Central Bohai Sea. The influence of riverine discharge on selenium levels can be seen from salinity isopleths, selenium distribution and species ratios. Near-bottom waters have similar selenium concentrations as to the surface waters in the Central Bohai Sea, whereas stratification takes place in the Bohai Strait and North Yellow sea. Based on the data of this study, a preliminary estimate of selenium budgets via riverine input is established. The seasonal variation of Se (IV)/Se (VI) ratio is maximum in Bohai Sea. The predominant species of selenium was selenate in autumn 1998. However, selenite became the dominant species in spring 1999. A simple box model was used to estimate the water-mass balance and selenium budgets for the Bohai Sea. Selenium budgets demonstrated that net sink of selenium can be mainly from the water column into bottom sediments and/or by transformation to other forms of selenium.

  7. Modeling nonequilibrium adsorption of MIB and sulfamethoxazole by powdered activated carbon and the role of dissolved organic matter competition.

    PubMed

    Shimabuku, Kyle K; Cho, Hyukjin; Townsend, Eli B; Rosario-Ortiz, Fernando L; Summers, R Scott

    2014-12-01

    This study demonstrates that the ideal adsorbed solution theory-equivalent background compound (IAST-EBC) as a stand-alone model can simulate and predict the powdered activated carbon (PAC) adsorption of organic micropollutants found in drinking water sources in the presence of background dissolved organic matter (DOM) under nonequilibrium conditions. The IAST-EBC represents the DOM competitive effect as an equivalent background compound (EBC). When adsorbing 2-methylisoborneol (MIB) with PAC, the EBC initial concentration was a similar percentage, on average 0.51%, of the dissolved organic carbon in eight nonwastewater impacted surface waters. Using this average percentage in the IAST-EBC model yielded good predictions for MIB removal in two nonwastewater impacted waters. The percentage of competitive DOM was significantly greater in wastewater impacted surface waters, and varied markedly in DOM size fractions. Fluorescence parameters exhibited a strong correlation with the percentage of competitive DOM in these waters. Utilizing such correlations in the IAST-EBC successfully modeled MIB and sulfamethoxazole adsorption by three different PACs in the presence of DOM that varied in competitive effect. The influence of simultaneous coagulant addition on PAC adsorption of micropollutants was also investigated. Coagulation caused the DOM competitive effect to increase and decrease with MIB and sulfamethoxazole, respectively. PMID:25371136

  8. Removal of dissolved organic matter in water-hyacinth waste-water treatment lagoons

    SciTech Connect

    Victoria-Rueda, C.H.

    1991-01-01

    Secondary treatment of domestic wastewater in water hyacinth lagoons was evaluated under experimental conditions to assess the role of the roots' bacterial biofilm in the removal of dissolved organic matter (DOM). Research was conducted to (1) quantify removal rates by the biofilm as a function of bulk DOM concentration, (2) formulate an analytical model of DOM removal incorporating biofilm activity, and (3) test the model response to variable organic loads in a pilot-scale plant. Removal of DOM by the biofilm was quantified in continuous-flow water hyacinth tanks at ten concentrations ranging from 45 to 330 g COD m {sup {minus}3} . Total DOM removal in the denitrifying, acetate-based experimental system was measured and partitioned into two fractions associated with the activity of biofilm and suspended bacteria. Calculated DOM removal by the biofilm was adjusted for the release of organic compounds by debris decomposition. Values of DOM removal were used to calculate oxygen transfer rates from the water hyacinth roots. A model of DOM removal in water hyacinth lagoons was formulated. The model, composed of four differential equations, was solved at steady-state conditions and the validity of its simulation results was tested in pilot-scale tanks. Hydraulic detection times ranging from 2 to 28 days were evaluated using biofilm density and concentrations of DOM and particulate organics as monitoring parameters of the model response. The observed decrease of suspended bacterial biomass along the tank was correctly simulated by the model, but predictions of effluent concentrations were not always consistent. Predicted values of biofilm bacterial mass were similar to those measured in the tanks, except when large algal populations were present in the film.

  9. Evidence for the enhanced lability of dissolved organic matter following permafrost slope disturbance in the Canadian High Arctic

    NASA Astrophysics Data System (ADS)

    Woods, Gwen C.; Simpson, Myrna J.; Pautler, Brent G.; Lamoureux, Scott F.; Lafrenière, Melissa J.; Simpson, André J.

    2011-11-01

    Arctic landscapes are believed to be highly sensitive to climate change and accelerated disturbance of permafrost is expected to significantly impact the rate of carbon cycling. While half the global soil organic matter (SOM) is estimated to reside in Arctic soils, projected warmer temperatures and permafrost disturbance will release much of this SOM into waterways in the form of dissolved organic matter (DOM). The spring thaw and subsequent flushing of soils releases the highest contributions of DOM annually but has historically been undersampled due to the difficulties of sampling during this period. In this study, passive samplers were placed throughout paired High Arctic watersheds during the duration of the 2008 spring flush in Nunavut, Canada. The watersheds are very similar with the exception of widespread active layer detachments (ALDs) that occurred within one of the catchments during a period of elevated temperatures in the summer of 2007. DOM samples were analyzed for structural and spectral characteristics via nuclear magnetic resonance (NMR) and fluorescence spectroscopy as well as vulnerability to degradation with simulated solar exposure. Lignin-derived phenols were further assessed utilizing copper(II) oxide (CuO) oxidation and gas chromatography/mass spectrometry (GC/MS). The samples were found to have very low dissolved lignin phenol content (˜0.07% of DOC) and appear to originate from primarily non-woody angiosperm vegetation. The acid/aldehyde ratios for dissolved vanillyl phenols were found to be high (up to 3.6), indicating the presence of highly oxidized lignin. Differences between DOM released from the ALD vs. the undisturbed watershed suggest that these shallow detachment slides have significantly impacted the quality of Arctic DOM. Although material released from the disturbed catchment was found to be highly oxidized, DOM in the lake into which this catchment drained had chemical characteristics indicating high contributions from microbial and/or primary productivity. The resulting pool of dissolved carbon within the lake appears to be more biologically- and photochemically-labile than material from the undisturbed system. These disturbances may have implications for projected climate warming; sustained elevated temperatures would likely perpetuate widespread ALDs and further affect carbon cycling in this environment.

  10. RESULTS OF EXPERIMENT TO DETERMINE CORROSION RATES FOR 304L IN HB-LINE DISSOLVER VESSEL VENTILATION SYSTEM

    SciTech Connect

    Mickalonis, J; Kathryn Counts, K

    2008-02-22

    Radioactive material being processed as part of the DE3013 program for HB-Line will result in the presence of chlorides, and in some cases fluorides, in the dissolver. Material Science and Technology developed an experimental plan to evaluate the impact of chloride on corrosion of the dissolver vessel ventilation system. The plan set test variables from the proposed operating parameters, previous test results, and a desired maximum chloride concentration for processing. The test variables included concentrations of nitric acid, fluorides and chlorides, and the presence of a welded and stressed metal coupon. Table 1 contains expected general corrosion rates in the HB-Line vessel vent system from dissolution of 3013 contents of varying nitric acid and chloride content. These general corrosion rates were measured upstream of the condenser in the experiment's offgas system near the entrance to the dissolver. However, they could apply elsewhere in the offgas system, depending on factors not simulated in the testing, including offgas system temperatures and airflow. Localized corrosion was significant in Tests One, Two, and Three. This corrosion is significant because it will probably be the first mode of penetration of the 304L steel in several places in the system. See Table 2. For Tests One and Three, the penetration rate of localized corrosion was much higher than that for general corrosion. It was approximately four times higher in Test One and at least 45 times higher in Test Three, penetrating an entire coupon thickness of 54 mils in 186 hours or less. There was no significant difference in corrosion between welded areas and un-welded areas on coupons. There was also no significant attack on stressed portions of coupons. It is probable that the lack of corrosion was because the stressed areas were facing downwards and offered no place for condensation or deposits to form. Had deposits formed, pitting may have occurred and led to stress corrosion cracking. The significant localized corrosion observed was usually associated with deposits. General corrosion on the offgas coupons was extremely high for the test containing 10,000 ppm chloride in the dissolver solution. Localized corrosion caused deep penetration of coupon surfaces with a solution of 2000 ppm chloride, both at 12 M and 8 M nitric acid. We recommend that when processing chloride-containing solutions, the pre-condenser side of the vessel vent system be inspected at a frequency calculated from acceptable material losses and expected general corrosion rate. The presence of deposits and heavy condensation during inspection should be taken as indicators of possibly severe localized corrosion.

  11. Dissolved Organic Carbon Concentrations in Tempe Town Lake: biogDissolved Organic Carbon Concentrations in Tempe Town Lake: biogeochemical & hydrologic processeseochemical & hydrologic processes 1Department of Geological Sciences, 871404, Arizona State Un

    E-print Network

    Hall, Sharon J.

    Dissolved Organic Carbon Concentrations in Tempe Town Lake: biogDissolved Organic Carbon Concentrations in Tempe Town Lake: biogeochemical & hydrologic processeseochemical & hydrologic processes 1Department of Geological Sciences, 871404, Arizona State University, Tempe, AZ 85287-1404 2 Department

  12. Dissolved pesticides, dissolved organic carbon, and water-quality characteristics in selected Idaho streams, April--December 2010

    USGS Publications Warehouse

    Reilly, Timothy J.; Smalling, Kelly L.; Wilson, Emma R.; Battaglin, William A.

    2012-01-01

    Water-quality samples were collected from April through December 2010 from four streams in Idaho and analyzed for a suite of pesticides, including fungicides, by the U.S. Geological Survey. Water samples were collected from two agricultural and two nonagricultural (control) streams approximately biweekly from the beginning of the growing season (April) through the end of the calendar year (December). Samples were analyzed for 90 pesticides using gas chromatography/mass spectrometry. Twenty-three pesticides, including 8 fungicides, 10 herbicides, 3 insecticides, and 2 pesticide degradates, were detected in 45 water samples. The most frequently detected compounds in the two agricultural streams and their detection frequencies were metolachlor, 96 percent; azoxystrobin, 79 percent; boscalid, 79 percent; atrazine, 46 percent; pendimethalin, 33 percent; and trifluralin, 33 percent. Dissolved-pesticide concentrations ranged from below instrumental limits of detection (0.5-1.0 nanograms per liter) to 771 nanograms per liter (hexazinone). The total number of pesticides detected in any given water sample ranged from 0 to 11. Only three pesticides (atrazine, fipronil, and simazine) were detected in samples from the control streams during the sampling period.

  13. DISTRIBUTION AND COMPOSITION OF DISSOLVED AND PARTICULATE ORGANIC CARBON IN NORTHERN SAN FRANCISCO BAY DURING LOW FRESHWATER FLOW CONDITIONS

    EPA Science Inventory

    The distribution of organic matter was studied in northern San Francisco Bay monthly through spring and summer 1996 along the salinity gradient from the Sacramento River to Central Bay. Dissolved constituents included monosaccharides (MONO), total carbohydrates (TCHO), dissolved ...

  14. Effects of sulfate deposition on pore water dissolved organic carbon, nutrients, and microbial enzyme activities in a northern peatland

    EPA Science Inventory

    Export of dissolved organic carbon from lakes and streams has increased throughout Europe and North America over the past several decades. One possible cause is altered deposition chemistry; specifically, decreasing sulfate inputs leading to changes in ionic strength and dissolve...

  15. Evaluating the origins and transformations of organic matter and dissolved inorganic nitrogen in two contrasting North Sea estuaries 

    E-print Network

    Ahad, Jason Michael Elias

    In order to delineate the potential sources and to understand the main controls on the biogeochemical cycling of dissolved and particulate organic matter (DOM, POM) and dissolved inorganic nitrogen (DIN) during estuarine ...

  16. A study of trends in dissolved oxygen and fecal coliform bacteria at NASQAN stations

    USGS Publications Warehouse

    Smith, Richard A.; Alexander, Richard B.

    1982-01-01

    Most stations in the U.S. Geological Survey's National Stream Quality Accounting Network show no significant trend in either dissolved oxygen concentration or fecal coliform bacteria population for the period October 1974. through October 1981. Of the stations which do show trends, however, most show improved water quality: thirty-one of a total of 276 stations show rising dissolved oxygen concentrations, while only 17 show decreasing concentrations. Decreases in fecal coliform populations have occurred at 21 stations while increases have occurred at only 12 stations. Approximately half of the stations showing improving trends in dissolved oxygen and fecal coliform bacteria are in the Missouri-Mississippi-Ohio River system. Decreases in dissolved oxygen have occurred at scattered locations in the Western and South-Central States. Rising bacterial populations occur most frequently in the Eastern and Central States Trends in dissolved oxygen concentration resulting from temperature changes occurring during the study period can be separated from trends caused by chemical or biological processes by analyzing computed values of dissolved oxygen deficit. About half of the observed trends in dissolved oxygen appear to be the result of changes in water temperature.

  17. Seasonal and interannual variability of dissolved oxygen around the Balearic Islands from hydrographic data

    NASA Astrophysics Data System (ADS)

    Balbín, R.; López-Jurado, J. L.; Aparicio-González, A.; Serra, M.

    2014-10-01

    Oceanographic data obtained between 2001 and 2011 by the Spanish Institute of Oceanography (IEO, Spain) have been used to characterise the spatial distribution and the temporal variability of the dissolved oxygen around the Balearic Islands (Mediterranean Sea). The study area includes most of the Western Mediterranean Sea, from the Alboran Sea to Cape Creus, at the border between France and Spain. Dissolved oxygen (DO) at the water surface is found to be in a state of equilibrium exchange with the atmosphere. In the spring and summer a subsurface oxygen supersaturation is observed due to the biological activity, above the subsurface fluorescence maximum. Minimum observed values of dissolved oxygen are related to the Levantine Intermediate Waters (LIW). An unusual minimum of dissolved oxygen concentrations was also recorded in the Alboran Sea Oxygen Minimum Zone. The Western Mediterranean Deep Waters (WMDW) and the Western Intermediate Waters (WIW) show higher values of dissolved oxygen than the Levantine Intermediate Waters due to their more recent formation. Using these dissolved oxygen concentrations it is possible to show that the Western Intermediate Waters move southwards across the Ibiza Channel and the deep water circulates around the Balearic Islands. It has also been possible to characterise the seasonal evolution of the different water masses and their dissolved oxygen content in a station in the Algerian sub-basin.

  18. Influence of dissolved organic substances in groundwater on sorption behavior of americium and neptunium

    SciTech Connect

    Boggs, S. Jr.; Seitz, M.G.

    1984-01-01

    Groundwaters typically contain dissolved organic carbon consisting largely of high molecular weight compounds of humic and fulvic acids. To evaluate whether these dissolved organic substances can enhance the tranport of radionuclides through the groundwater system, experiments were conducted to examine the sorption of americium and neptunium onto crushed basalt in the presence of dissolved humic- and fulvic-acid organic carbon introduced into synthetic groundwater. The partitioning experiments with synthetic groundwater show that increasing the concentration of either humic or fulvic acid in the water has a significant inhibiting effect on sorption of both americium and neptunium. At 22/sup 0/C, adsorption of these radionuclides, as measured by distribution ratios (the ratio of nuclide sorbed onto the solid to nuclide in solution at the end of the experiment), decreased by 25% to 50% by addition of as little as 1 mg/L dissolved organic carbon and by one to two orders of magnitude by addition of 100 to 200 mg/L dissolved organic carbon. Distribution ratios measured in solutions reacted at 90/sup 0/C similarly decreased with the addition of dissolved organic carbon but generally ranged from one to two orders of magnitude higher than those determined in the 22/sup 0/C experiment. These results suggest that organic carbon dissolved in deep groundwaters may significantly enhance the mobility of radionuclides of americium and neptunium. 23 references, 5 figures, 11 tables.

  19. Ocean Warming–Acidification Synergism Undermines Dissolved Organic Matter Assembly

    PubMed Central

    Chen, Chi-Shuo; Anaya, Jesse M.; Chen, Eric Y-T; Farr, Erik; Chin, Wei-Chun

    2015-01-01

    Understanding the influence of synergisms on natural processes is a critical step toward determining the full-extent of anthropogenic stressors. As carbon emissions continue unabated, two major stressors—warming and acidification—threaten marine systems on several scales. Here, we report that a moderate temperature increase (from 30°C to 32°C) is sufficient to slow— even hinder—the ability of dissolved organic matter, a major carbon pool, to self-assemble to form marine microgels, which contribute to the particulate organic matter pool. Moreover, acidification lowers the temperature threshold at which we observe our results. These findings carry implications for the marine carbon cycle, as self-assembled marine microgels generate an estimated global seawater budget of ~1016 g C. We used laser scattering spectroscopy to test the influence of temperature and pH on spontaneous marine gel assembly. The results of independent experiments revealed that at a particular point, both pH and temperature block microgel formation (32°C, pH 8.2), and disperse existing gels (35°C). We then tested the hypothesis that temperature and pH have a synergistic influence on marine gel dispersion. We found that the dispersion temperature decreases concurrently with pH: from 32°C at pH 8.2, to 28°C at pH 7.5. If our laboratory observations can be extrapolated to complex marine environments, our results suggest that a warming–acidification synergism can decrease carbon and nutrient fluxes, disturbing marine trophic and trace element cycles, at rates faster than projected. PMID:25714090

  20. Ultrafiltration of nonionic surfactants and dissolved organic matter.

    PubMed

    Müller, Margit B; Fritz, Wolfgang; Lankes, Ulrich; Frimmel, Fritz H

    2004-02-15

    A brownwater sample with a high content of humic substances (HS) was fractionated by multistage ultrafiltration (mst-UF) into five fractions with nominal molecular weights ranging from >30 to <1 kDa. Fractions were characterized with respect to molecular size distribution and structure. Size exclusion chromatography with online DOC detection revealed that mst-UF yielded fractions with decreasing Mp (molecular weight at peak maximum) and polydispersities from nominally large to small mst-UF fractions. 13C MAS NMR analysis showed that the content of carbohydrate structures decreased from the original sample toward smaller molecular weight (MW) fractions, which in turn contained more carboxylic groups and branched aliphatic structures. Specific UV absorbances (SUVA254) were highest in the >30 kDa fraction and decreased with decreasing MW. To evaluate whether separation mechanisms other than size exclusion were of importance during the fractionation, the behavior of low molecular weight model compounds (MC) with a range of polarities was studied. Recoveries decreased with increasing hydrophobicity of the MC. For selected nonylphenol ethoxylates and 4-nonylphenol the recovery correlated well with the hydrophile-lipophile balance value. The presence of dissolved organic matter (DOM) caused an additional loss of hydrophobic MC, possibly because of sorption of the compounds onto DOM fouling layers. The hydrophilic MC caffeine was recovered almost completely (85-86%) regardless of the DOM content of the model solution. It was concluded that size exclusion was the dominant fractionation mechanism for caffeine, whereas hydrophobic interactions played a major role during the mst-UF fractionation of nonpolar contaminants. For a better understanding of the behavior of polyfunctional molecules such as HS, the effect of other physicochemical properties needs to be investigated in further studies. PMID:14998027

  1. Dissolved air flotation of polishing wastewater from semiconductor manufacturer.

    PubMed

    Liu, J C; Lien, C Y

    2006-01-01

    The feasibility of the dissolved air flotation (DAF) process in treating chemical mechanical polishing (CMP) wastewater was evaluated in this study. Wastewater from a local semiconductor manufacturer was sampled and characterised. Nano-sized silica (77.6 nm) with turbidity of 130 +/- 3 NTU was found in the slightly alkaline wastewater with traces of other pollutants. Experimental results indicated removal efficiency of particles, measured as suspended particle or turbidity, increased with increasing concentration of cationic collector cetyltrimethyl ammonium bromide (CTAB). When CTAB concentration was 30 mg/L, pH of 6.5 +/- 0.1 and recycle ratio of 30%, very effective removal of particles (> 98%) was observed in saturation pressure range of 4 to 6 kg/cm2, and the reaction proceeded faster under higher pressure. Similarly, the reaction was faster under the higher recycle ratio, while final removal efficiency improved slightly as the recycle ratio increased from 20 to 40%. An insignificant effect of pH on treatment efficiency was found as pH varied from 4.5 to 8.5. The presence of activator, Al3+ and Fe3+, enhanced the system performance. It is proposed that CTAB adsorbs on silica particles in polishing wastewater through electrostatic interaction and makes particles more hydrophobic. The increase in hydrophobicity results in more effective bubble-particle collisions. In addition, flocculation of silica particles through bridging effect of collector was found; it is believed that flocculation of particles also contributed to flotation. Better attachment between gas bubble and solid, higher buoyancy and higher air to solid ratio all lead to effective flotation. PMID:16752774

  2. Dissolved organic matter enhances microbial mercury methylation under sulfidic conditions.

    PubMed

    Graham, Andrew M; Aiken, George R; Gilmour, Cynthia C

    2012-03-01

    Dissolved organic matter (DOM) is generally thought to lower metal bioavailability in aquatic systems due to the formation of metal-DOM complexes that reduce free metal ion concentrations. However, this model may not be pertinent for metal nanoparticles, which are now understood to be ubiquitous, sometimes dominant, metal species in the environment. The influence of DOM on Hg bioavailability to microorganisms was examined under conditions (0.5-5.0 nM Hg and 2-10 ?M sulfide) that favor the formation of ?-HgS(s) (metacinnabar) nanoparticles. We used the methylation of stable-isotope enriched (201)HgCl(2) by Desulfovibrio desulfuricans ND132 in short-term washed cell assays as a sensitive, environmentally significant proxy for Hg uptake. Suwannee River humic acid (SRHA) and Williams Lake hydrophobic acid (WLHPoA) substantially enhanced (2- to 38-fold) the bioavailability of Hg to ND132 over a wide range of Hg/DOM ratios (9.4 pmol/mg DOM to 9.4 nmol/mg DOM), including environmentally relevant ratios. Methylmercury (MeHg) production by ND132 increased linearly with either SRHA or WLHPoA concentration, but SRHA, a terrestrially derived DOM, was far more effective at enhancing Hg-methylation than WLHPoA, an aquatic DOM dominated by autochthonous sources. No DOM-dependent enhancement in Hg methylation was observed in Hg-DOM-sulfide solutions amended with sufficient l-cysteine to prevent ?-HgS(s) formation. We hypothesize that small HgS particles, stabilized against aggregation by DOM, are bioavailable to Hg-methylating bacteria. Our laboratory experiments provide a mechanism for the positive correlations between DOC and MeHg production observed in many aquatic sediments and wetland soils. PMID:22309093

  3. Dissolved organic matter kinetically controls mercury bioavailability to bacteria.

    PubMed

    Chiasson-Gould, Sophie A; Blais, Jules M; Poulain, Alexandre J

    2014-03-18

    Predicting the bioavailability of inorganic mercury (Hg) to bacteria that produce the potent bioaccumulative neurotoxin monomethylmercury remains one of the greatest challenges in predicting the environmental fate and transport of Hg. Dissolved organic matter (DOM) affects mercury methylation due to its influence on cell physiology (as a potential nutrient) and its influence on Hg(II) speciation in solution (as a complexing agent), therefore controlling Hg bioavailability. We assessed the role of DOM on Hg(II) bioavailability to a gram-negative bacterium bioreporter under oxic pseudo- and nonequilibrium conditions, using defined media and field samples spanning a wide range of DOM levels. Our results showed that Hg(II) was considerably more bioavailable under nonequilibrium conditions than when DOM was absent or when Hg(II) and DOM had reached pseudoequilibrium (24 h) prior to cell exposure. Under these enhanced uptake conditions, Hg(II) bioavailability followed a bell shaped curve as DOM concentrations increased, both for defined media and natural water samples, consistent with bioaccumulation results in a companion paper (this issue) observed for amphipods. Experiments also suggest that DOM may not only provide shuttle molecules facilitating Hg uptake, but also alter cell wall properties to facilitate the first steps toward Hg(II) internalization. We propose the existence of a short-lived yet critical time window (<24 h) during which DOM facilitates the entry of newly deposited Hg(II) into aquatic food webs, suggesting that the bulk of mercury incorporation in aquatic food webs would occur within hours following its deposition from the atmosphere. PMID:24524696

  4. Biogeochemical Processes That Produce Dissolved Organic Matter From Wheat Straw

    USGS Publications Warehouse

    Wershaw, Robert L.; Rutherford, David W.; Leenheer, Jerry A.; Kennedy, Kay R.; Cox, Larry G.; Koci, Donald R.

    2003-01-01

    The chemical reactions that lead to the formation of dissolved organic matter (DOM) in natural waters are poorly understood. Studies on the formation of DOM generally are complicated because almost all DOM isolates have been derived from mixtures of plant species composed of a wide variety of different types of precursor compounds for DOM formation. This report describes a study of DOM derived mainly from bales of wheat straw that had been left in a field for several years. During this period of time, black water from the decomposing wheat straw accumulated in pools in the field. The nuclear magnetic resonance and infrared spectra of the black water DOM indicate that it is composed almost entirely of lignin and carbohydrate polymeric units. Analysis by high-performance size-exclusion chromatography with multi-angle laser-light scattering detection indicates that the number average molecular weight of the DOM is 124,000 daltons. The results presented in this report indicate that the black water DOM is composed of hemicellulose chains cross-linked to lignin oligomers. These types of structures have been shown to exist in the hemicellulose matrix of plant cell walls. The cross-linked lignin-hemicellulose complexes apparently were released from partially degraded wheat-straw cell walls with little alteration. In solution in the black water, these lignin-hemicellulose polymers fold into compact globular particles in which the nonpolar parts of the polymer form the interiors of the particles and the polar groups are on the exterior surfaces of the particles. The tightly folded, compact conformation of these particles probably renders them relatively resistant to microbial degradation. This should be especially the case for the aromatic lignin structures that will be buried in the interiors of the particles.

  5. Dissolved Organic Carbon in Groundwater Overlain by Irrigated Sugarcane.

    PubMed

    Thayalakumaran, Thabo; Lenahan, Matthew J; Bristow, Keith L

    2015-07-01

    Elevated dissolved organic carbon (DOC) has been detected in groundwater beneath irrigated sugarcane on the Burdekin coastal plain of tropical northeast Australia. The maximum value of 82?mg/L is to our knowledge the highest DOC reported for groundwater beneath irrigated cropping systems. More than half of the groundwater sampled in January 2004 (n?=?46) exhibited DOC concentrations greater than 30?mg/L. DOC was progressively lower in October 2004 and January 2005, with a total decrease greater than 90% indicating varying load(s) to the aquifer. It was hypothesized that the elevated DOC found in this groundwater system is sourced at or near the soil surface and supplied to the aquifer via vertical recharge following above average rainfall. Possible sources of DOC include organic-rich sugar mill by-products applied as fertilizer and/or sugarcane sap released during harvest. CFC-12 vertical flow rates supported the hypothesis that elevated DOC (>40?mg/L) in the groundwater results from recharge events in which annual precipitation exceeds 1500?mm/year (average?=?960?mm/year). Occurrence of elevated DOC concentrations, absence of electron acceptors (O2 and NO3 (-) ) and both Fe(2+) and Mn(2+) greater than 1?mg/L in shallow groundwater suggest that the DOC compounds are chemically labile. The consequence of high concentrations of labile DOC may be positive (e.g., denitrification) or negative (e.g., enhanced metal mobility and biofouling), and highlights the need to account for a wider range of water quality parameters when considering the impacts of land use on the ecology of receiving waters and/or suitability of groundwater for irrigated agriculture. PMID:25213667

  6. Dissolved iron supply limits early growth of estuarine mangroves.

    PubMed

    Alongi, Daniel M

    2010-11-01

    Three mesocosm experiments were performed in an outdoor facility to quantify the responses of five mangrove species grown from seedling to sapling stage to increasing rates of dissolved iron supply. Stem extension and biomass of mangroves were measured in the first two experiments, and in the third experiment, rates of microbial iron reduction were measured in relation to stem extension of two mangrove species. In all experiments, mangrove growth was enhanced by increasing iron supply, although some species showed iron toxicity at the higher supply rates. In the first two experiments, stem extension rates of Rhizophora apiculata, Bruguiera gymnorrhiza, and Xylocarpus moluccensis best fit Gaussian curves with maximal growth at supply rates of 50-60 mmol Fe x m(-2) x d(-1), whereas growth of Avicennia marina and Ceriops tagal increased to the highest rate (100 mmol Fe x m(-2) x d(-1)) of iron supply. Changes in leaf chlorophyll concentrations and iron content of roots mirrored the growth responses. In the third experiment, rates of microbial iron reduction were greater with R. apiculata and A. marina than in controls without plants; for both species, there was a positive relationship between stem extension and iron reduction. The rates of iron reduction and rates of iron supplied to the plants were well within the range of interstitial iron concentrations and rates of iron reduction found in the natural mangrove soils from which the seedlings were obtained. The responses of these species show that mangroves growing from seedling to sapling stage have a strong nutritional requirement for iron, and that there is a close relationship between plant roots and the activities of iron-reducing bacteria. These results suggest that mangrove growth may be limited in some natural forests by the rate at which iron is solubilized by iron-reducing bacteria. Such biogeochemical conditions have significant implications for successful recruitment, establishment, and early growth of mangroves. PMID:21141184

  7. Loop flow analysis of dissolved reactive phosphorus in aqueous samples.

    PubMed

    Ma, Jian; Li, Quanlong; Yuan, Dongxing

    2014-06-01

    The current flow based method for the determination of dissolved reactive phosphorus (DRP) suffers interference from salinity (e.g. index refractive difference) and the incidentally formed bubbles, which can be a problem for optical detection. Here we reported a simple and robust loop flow analysis (LFA) method for accurate measurement of DRP in different aqueous samples. The chemistry is based on the classic phosphomolybdenum blue (PMB) reaction and the PMB formed in a novel cross-shaped flow cell was detected at 700 nm using a miniature spectrophotometer. The effects of reagents on the kinetic formation of PMB were evaluated. The detection limit was 32 nM with an optical pathlength of 1cm and the relative standard deviations for repetitive determinations of 1, 2 and 8 µM phosphate solutions were 1.8% (n=113, without any stoppage during repeating analysis for >7h), 1.0% (n=49) and 0.39% (n=9), respectively. The analysis time was 4 min sample(-1). The effects of salinity and interfering ions (silicate and arsenate) were evaluated and showed no interference under the proposed protocol for DRP analysis. Using the LFA method, different aqueous samples with a salinity range of 0-34 were analyzed and the results showed excellent agreement with the reference method (slope 0.9982±0.0063, R(2)=0.9987, n=34). Recoveries for spiked samples varied from 95.4% to 103.7%. The proposed method showed insignificant interference from salinity, silicate and arsenate, higher reproducibility, easier operation and was free of the bubble problem. PMID:24725885

  8. Modeling the depletion of dissolved oxygen in a lake due to algal bloom: Effect of time delay

    NASA Astrophysics Data System (ADS)

    Misra, A. K.; Chandra, Peeyush; Raghavendra, V.

    2011-10-01

    We propose and analyze a non-linear mathematical model for algal bloom in a lake to account for the delay in conversion of detritus into nutrients. It is assumed that there is a continuous inflow of nutrients in the lake due to agricultural run off. The model involves four variables, namely nutrient concentration, algal population density, detritus density and dissolved oxygen concentration. The dynamics of the model is studied in terms of local stability analysis and Hopf-bifurcation analysis. It is found that the positive equilibrium of the model may switch from stability to instability to stability, and eventually instability sets in under certain conditions. The numerical simulation is performed to support the analytical results.

  9. Groundwater cleanup by in-situ sparging. XIII. Random air channels for sparing of dissolved and nonaqueous phase volatiles

    SciTech Connect

    Wilson, D.J.; Clarke, A.N. [Eckenfelder, Inc., Nashville, TN (United States); Kaminski, K.M.; Chang, E.Y. [Martin Luther King Magnet High School, Nashville, TN (United States)

    1997-12-01

    A mathematical model is developed to simulate the sparging of dissolved volatile organic compounds (VOCs) and nonaqueous phase liquid (NAPL) from contaminated aquifers. The sparging air moves through the aquifer in persistent, random channels, to which VOC must move by diffusion/dispersion to be removed. The dependence of the rate of remediation on the various model parameters is investigated and some practical conclusions are reached regarding the operation of air sparging wells for aquifer remediation. VOCs of low water solubility (such as alkanes) and present as NAPL are found to be removed by air sparging much more slowly than VOCs of higher water solubility (such as benzene, toluene, ethylbenzene and xylenes) and present as NAPL, due to the very small maximum concentration gradients which can be maintained around droplets of the former. These small concentration gradients result in very slow rates of NAPL solution.

  10. Characterization of Dissolved Solids in Water Resources of Agricultural Lands near Manila, Utah, 2004-05

    USGS Publications Warehouse

    Gerner, Steven J.; Spangler, L.E.; Kimball, B.A.; Naftz, D.L.

    2006-01-01

    Agricultural lands near Manila, Utah, have been identified as contributing dissolved solids to Flaming Gorge Reservoir. Concentrations of dissolved solids in water resources of agricultural lands near Manila, Utah, ranged from 35 to 7,410 milligrams per liter. The dissolved-solids load in seeps and drains in the study area that discharge to Flaming Gorge Reservoir ranged from less than 0.1 to 113 tons per day. The most substantial source of dissolved solids discharging from the study area to the reservoir was Birch Spring Draw. The mean daily dissolved-solids load near the mouth of Birch Spring Draw was 65 tons per day. The estimated annual dissolved-solids load imported to the study area by Sheep Creek and Peoples Canals is 1,330 and 13,200 tons, respectively. Daily dissolved-solid loads discharging to the reservoir from the study area, less the amount of dissolved solids imported by canals, for the period July 1, 2004, to June 30, 2005, ranged from 90 to 289 tons per day with a mean of 142 tons per day. The estimated annual dissolved-solids load discharging to the reservoir from the study area, less the amount of dissolved solids imported by canals, for the same period was 51,900 tons. Of this 51,900 tons of dissolved solids, about 9,000 tons may be from a regional source that is not associated with agricultural activities. The salt-loading factor is 3,670 milligrams per liter or about 5.0 tons of dissolved solids per acre-foot of deep percolation in Lucerne Valley and 1,620 milligrams per liter or 2.2 tons per acre-foot in South Valley. The variation of 87Sr with strontium concentration indicates some general patterns that help to define a conceptual model of the processes affecting the concentration of strontium and the 87Sr isotopic ratio in area waters. As excess irrigation water percolates through soils derived from Mancos Shale, the 87Sr isotopic ratio (0.21 to 0.69 permil) approaches one that is typical of deep percolation from irrigation on Mancos Shale. The boron concentration and 11B value for the water sample from Antelope Wash, being distinctly different from water samples from other sites, is evidence that water in Antelope Wash may contain a substantial component of regional ground-water flow.

  11. Dissolved-solids concentrations of ground water in the Sacramento Valley, California

    USGS Publications Warehouse

    Fogelman, Ronald P.

    1982-01-01

    The general quality of the ground water in the Sacramento Valley , Calif., in terms of dissolved-solids concentration is considered good for irrigation, domestic, and most other uses. This map shows the distribution of dissolved-solids concentrations and is based on about 1,330 chemical analyses collected from about 900 wells between 1974 and 1978. On the west side of the valley some of the smaller streams contribute water of higher dissolved-solids concentrations to the ground water. The sources of these waters are thought to be the upper Cretaceous Chico Formation or marine deposits of Early Cretaceous age that are exposed in the Coast Ranges. (USGS)

  12. TRUEX flowsheet testing for the removal of the actinides from dissolved ICPP zirconium calcine using centrifugal contactors

    SciTech Connect

    Herbst, R.S.; Law, J.D.; Brewer, K.N.; Todd, T.A.

    1997-12-01

    Solid calcine is one of the wastes under evaluation for TRU removal by the TRUEX process. The calcine must first be dissolved in nitric acid prior to the removal of TRUs and fission products. Zirconium type calcine (generated from zirconium fuel reprocessing raffinates) comprises the majority of the calcine currently stored at the ICPP. The zirconium calcines average 18.3 wt% ZrO{sub 2} and are anticipated to be the most challenging to treat with regards to TRU removal because of the large zirconium content. This paper reports the results from a countercurrent flowsheet test performed with a dissolved calcine simulant in a 2-cm centrifugal contractor pilot plant. The simulant was spiked with radioactive {sup 241}Am and {sup 95}Zr to facilitate analysis and evaluate the behavior of the actinides. Flooding and precipitate formation were observed in the strip section during the flowsheet testing. It is postulated that the flooding occurred as a result of precipitate formation. The precipitate was determined to be ZrPO{sub 4} and was likely formed due the excessive amount of Zr carried into the strip section with the organic phase. Roughly 65% of the Zr in the feed was extracted. Of the extracted Zr, 15.6% reported to the strip product and 15.1% ended up in the organic effluent, indicating the strip section was ineffective at re-extracting Zr. The poor strip section performance was probably due to the precipitation and concomitant flooding problems encountered in the test, resulting in the strip section never achieving steady state operating conditions. Despite the obvious problems encountered during the test, > 99.18% of the americium was removed from the feed in the extraction section. This may be slightly lower than the anticipated 99.9% Am removal efficiency necessary to insure the < 10 nCi/g TRU content in the LLW raffinate.

  13. Biogeochemical controls on seasonal variations of the stable isotopes of dissolved oxygen and dissolved inorganic carbon in Castle Lake, CA

    NASA Astrophysics Data System (ADS)

    Brown, J. M.; Poulson, S. R.

    2010-12-01

    The purpose of this project is to perform a seasonal dissolved oxygen (DO) and dissolved inorganic carbon (DIC) stable isotope (?18O, ?13C) study to assess the fluctuations in biogeochemical processes with depth in a lake. DO and DIC concentrations and stable isotope compositions (?18O-DO, ?13C-DIC) have been used as a technique to study the systematics of diurnal freshwater biogeochemical processes, primarily photosynthesis, respiration, and gas-exchange (e.g. Quay et al. 1995, Trojanowska et al. 2008). For example, photosynthesis produces DO isotopically identical to the host water, typically light relative to atmospheric oxygen (+23.5‰), while respiration preferentially consumes isotopically light DO. Diel ?18O-DO and ?13C-DIC studies in rivers (e.g. Parker et al. 2005, Parker et al. 2010, Poulson & Sullivan 2010) have been used to determine the rates of biogeochemical processes over a 24h time scale. However, similar studies in lakes are rare, for either diel or seasonal time scales. The focus of this project is Castle Lake, 12km southwest of Mt. Shasta, CA, at an elevation of 1660m. Castle Lake is an alpine, meso-oligotrophic lake with a 19ha surface area and a maximum depth of up to 35m. This project consists of sampling profiles, 2-3 weeks apart, throughout the 2010 field season for monitoring seasonal depth trends, with measurements of DO concentration, temperature, pH, alkalinity, specific conductivity, PAR, chlorophyll concentration, ?18O-DO, ?13C-DIC, ?18O-H2O, and ?D-H2O. Diel measurements of DO concentration, temperature, pH, specific conductivity, PAR, and chlorophyll concentration have also been performed at various depths. To date, the profile data collected at Castle Lake show various seasonal changes, starting after ice-out (late June 2010) through mid-August 2010. DO profiles display a positive heterograde trend with a maximum of 11.33mg/L at 12m in mid-August and minima of ?0.12mg/L near the lake bottom. DIC concentrations increase with depth and with time up to 2mmol/L at 30m by mid-August. pH ranges from 5.9-7.5 and consistently increases in the metalimnion (5-15m) with the season. ?18O-DO profiles show inverse trends relative to DO concentration, and range from +15.8 to +27.8‰ after ice-out and from +10.2 to +30.9‰ in mid-August. ?13C-DIC profiles also show inverse trends relative to DIC concentration, reach a maximum of -12 to -10‰, generally in the metalimnion, and a minimum of down to -18‰ near the bottom of the hypolimnion (28-30m sampling depth). DO concentration, ?18O-DO, DIC concentration, and ?13C-DIC data all suggest that: photosynthesis is the principal process affecting DO in the metalimnion; that respiration is the dominant process affecting DIC in the hypolimnion; and that both processes increase in magnitude over the course of the season. To date, no significant diel variations of DO or pH have been observed. The ?18O-DO and ?13C-DIC results thus far are consistent with systematic variations of photosynthesis and respiration rates during the course of a season, suggesting the analyses in this study provide a reliable means for the quantitative study of biogeochemical processes in lakes on a seasonal time scale.

  14. Analytical Determinations of the Phenolic Content of Dissolved Organic Matter

    NASA Astrophysics Data System (ADS)

    Pagano, T.; Kenny, J. E.

    2010-12-01

    Indicators suggest that the amount of dissolved organic matter (DOM) in natural waters is increasing. Climate Change has been proposed as a potential contributor to the trend, and under this mechanism, the phenolic content of DOM may also be increasing. We have explored the possibility of assessing the phenolic character of DOM using fluorescence spectroscopy as a more convenient alternative to wet chemistry methods. In this work, parallel factor analysis (PARAFAC) was applied to fluorescence excitation emission matrices (EEMs) of humic samples in an attempt to analyze their phenolic content. The PARAFAC results were correlated with phenol concentrations derived from the Folin-Ciocalteau reagent-based method. The reagent-based method showed that the phenolic content of five International Humic Substance Society (IHSS) DOM samples vary from approximately 5 to 22 ppm Tannic Acid Equivalents (TAE) in phenol concentration. A five-component PARAFAC fit was applied to the EEMs of the IHSS sample dataset and it was determined by PARAFAC score correlations with phenol concentrations from the reagent-based method that components C1 (R2=0.78), C4 (R2=0.82), and C5 (R2=0.88) have the highest probability of containing phenolic groups. Furthermore, when the scores of components C4 and C5 were summed, the correlation improved (R2=0.99). Likewise, when the scores of C1, C4, and C5 were summed, their correlations were stronger than their individual parts (R2=0.89). Since the reagent-based method is providing an indicator of “total phenol” amount, regardless of the exact molecular structure of C1, C4, and C5, it seems reasonable that each of these components individually contributes a portion to the summed “total phenol” profile, and that the sum of their phenol-related spectral parts represents a larger portion of the “total phenol” index. However, when the sum of all five components were plotted against the reagent-based phenol concentrations, due to the considerable impact of largely non-phenolic components C2 (R2=0.23) and C3 (R2=0.35), the correlation was quite poor (or no correlation at all with R2=0.10). The results show the potential for PARAFAC analysis of multidimensional fluorescence data to be a tool for monitoring the phenolic content of DOM. Applications include assessing the potential for formation of disinfection byproducts in the treatment of drinking water and monitoring the impact of Climate Change on the phenolic character of DOM.

  15. Investigation of runoff generation from anthropogenic sources with dissolved xenobiotics

    NASA Astrophysics Data System (ADS)

    Krein, A.; Pailler, J.; Guignard, C.; Iffly, J.; Pfister, L.; Hoffmann, L.

    2009-04-01

    In the experimental Mess basin (35 km2, Luxembourg) dissolved xenobiotics in surface water are used to study the influences of anthropogenic sources like separated sewer systems on runoff generation. Emerging contaminants like pharmaceuticals are of growing interest because of their use in large quantities in human and veterinary medicine. The amounts reaching surface waters depend on rainfall patterns, hydraulic conditions, consumption, metabolism, degradation, and disposal. The behaviour of endocrine disruptors including pharmaceuticals in the aquatic environment is widely unknown. The twelve molecules analyzed belong to three families: the estrogens, the antibiotics (sulfonamides, tetracyclines), and the painkillers (ibuprofen, diclofenac). Xenobiotics can be used as potential environmental tracers for untreated sewerage. Our results show that the concentrations are highly variable during flood events. The highest concentrations are reached in the first flush period, mainly during the rising limb of the flood hydrographs. As a result of the kinematic wave effect the concentration peak occurs in some cases a few hours after the discharge maximum. In floodwater (eleven floods, 66 samples) the highest concentrations were measured for ibuprofen (?g/l range), estrone, and diclofenac (all ng/l range). From the tetracycline group, essentially tetracycline itself is of relevance, while the sulfonamides are mainly represented by sulfamethoxazole (all in ng/l range). In the Mess River the pharmaceuticals fluxes during flood events proved to be influenced by hydrological conditions. Different pharmaceuticals showed their concentration peaks during different times of a flood event. An example is the estrone peak that - during summer flash floods - often occurred one to two hours prior to the largest concentrations of the painkillers. This suggests for more sources than the sole storm drainage through the spillway of the single sewage water treatment plant, different transport velocities for single compounds or the existence of substance separating buffer storage in the stream network. In conditions of low intensity rainfall events and a few days of antecedent dry weather, acute peaks of pollution are discharged in the receiving waters. The influence of housing areas, main roads and sewer systems are obvious. These are characterized by rapid source depletion. Precipitation events of very small intensity and amount make themselves visible often as single peak storm events, which result predominantly from the sealed surface of this area. More accurate assessment of pollutant loads entering urban receiving water bodies is needed for improving urban storm water management and meeting water quality regulations.

  16. PHYSICAL AND BIOLOGICAL CONTROLS ON DISSOLVED OXYGEN DYNAMICS IN PENSACOLA BAY, FL

    EPA Science Inventory

    Nutrient enrichment of estuaries and coastal waters can contribute to hypoxia (low dissolved oxygen) by increasing primary production and biological oxygen demand. Other factors, however, contribute to hypoxia and affect the susceptibility of coastal waters to hypoxia. Hypoxia fo...

  17. Consolidated fuel reprocessing program: a mathematical model for liquid flow transients in a rotary dissolver

    SciTech Connect

    Lewis, B. E.; Weber, F. E.

    1980-10-01

    A model describing the liquid outlet response to perturbations in the flow to a compartmented rotary dissolver has been developed. The model incorporates stagewise differential material balances coupled with the general equation for flow over a weir to calculate acid concentrations and liquid volumes in each stage. Data were taken from step-change flow experiments conducted on a 0.5-t/d rotary dissolver. The predicted response of the model was in good agreement with the data from the dissolver experiments. All constants in the model were obtained by independent tests. The model appears to be applicable over a wide range of dissolver operating conditions; however, temperature fluctuations and the presence of solids were not addressed.

  18. CYCLING OF DISSOLVED ELEMENTAL MERCURY IN ARCTIC ALASKAN LAKES. (R829796)

    EPA Science Inventory

    Aqueous production and water-air exchange of elemental mercury (Hg0) are important features of the environmental cycling of Hg. We investigated Hg0 cycling in ten Arctic Alaskan lakes that spanned a wide range in physicochemical characteristics. Dissolved...

  19. Spatial variability of total dissolved copper and copper speciation in the inshore waters of Bermuda.

    PubMed

    Oldham, V E; Swenson, M M; Buck, K N

    2014-02-15

    Total dissolved copper (Cu) and Cu speciation were examined from inshore waters of Bermuda, in October 2009 and July-August 2010, to determine the relationship between total dissolved Cu, Cu-binding ligands and bioavailable, free, hydrated Cu(2+) concentrations. Speciation was performed using competitive ligand exchange-adsorptive cathodic stripping voltammetry (CLE-ACSV). Mean total dissolved Cu concentrations ranged from 1.4 nM to 19.2 nM, with lowest concentrations at sites further from shore, consistent with previous measurements in the Sargasso Sea, and localized Cu enrichment inshore in enclosed harbors. Ligand concentrations exceeded dissolved [Cu] at most sites, and [Cu(2+)] were correspondingly low at those sites, typically <10(-13) M. One site, Hamilton Harbour, was found to have [Cu] in excess of ligands, resulting in [Cu(2+)] of 10(-10.7) M, and indicating that Cu may be toxic to phytoplankton here. PMID:24461699

  20. Influence of carbonization methods on the aromaticity of pyrogenic dissolved organic carbon

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dissolved organic carbon (DOC) components of soil amendments such as biochar will influence the fundamental soil chemistry including the metal speciation, nutrient availability, and microbial activity. Quantitative correlation is necessary between (i) pyrogenic DOC components of varying aromaticity...

  1. Dissolved organic matter discharge in the six largest arctic rivers-chemical composition and seasonal variability 

    E-print Network

    Rinehart, Amanda J.

    2009-05-15

    of dissolved organic matter (DOM) in the six largest Arctic rivers (Yukon, Mackenzie, Ob, Yenisei, Lena and Kolyma) using optical properties (UV-Vis Absorbance and Fluorescence) and lignin phenol analysis. We also investigated differences between rivers and how...

  2. Chemical characterization of dissolved organic matter (DOM) in seawater : structure, cycling, and the role of biology

    E-print Network

    Quan, Tracy M. (Tracy Michelle), 1977-

    2005-01-01

    The goal of this thesis is to investigate three different areas relating to the characterization of dissolved organic matter (DOM): further determination of the chemical compounds present in high molecular weight DOM ...

  3. Determining Passive Sampler Partition Coefficients for Dissolved-phase Organic Contaminants

    EPA Science Inventory

    Passive samplers are used for environmental and analytical purposes to measure dissolved nonionic organic contaminants (NOCs) by absorption from a contaminated medium into a clean phase, usually in the form of a synthetic organic film. Recently developed passive sampler techniqu...

  4. Dissolved phosphorus transport from soil to surface water in catchments with different land use.

    PubMed

    Verheyen, Dries; Van Gaelen, Nele; Ronchi, Benedicta; Batelaan, Okke; Struyf, Eric; Govers, Gerard; Merckx, Roel; Diels, Jan

    2015-03-01

    Diffuse phosphorus (P) export from agricultural land to surface waters is a significant environmental problem. It is critical to determine the natural background P losses from diffuse sources, but their identification and quantification is difficult. In this study, three headwater catchments with differing land use (arable, pasture and forest) were monitored for 3 years to quantify exports of dissolved (<0.45 µm) reactive P and total dissolved P. Mean total P exports from the arable catchment ranged between 0.08 and 0.28 kg ha(-1) year(-1). Compared with the reference condition (forest), arable land and pasture exported up to 11-fold more dissolved P. The contribution of dissolved (<0.45 µm) unreactive P was low to negligible in every catchment. Agricultural practices can exert large pressures on surface waters that are controlled by hydrological factors. Adapting policy to cope with these factors is needed for lowering these pressures in the future. PMID:25681980

  5. PRODUCTION AND LOSS OF DISSOLVED GASEOUS MERCURY IN COASTAL SEAWATER (R824778)

    EPA Science Inventory

    The formation of dissolved gaseous mercury (DGM, mainly composed of elemental mercury, Hg0) in the surface ocean and its subsequent removal through volatilization is an important component of the global mercury (Hg) cycle. We studied DGM production an...

  6. DISSOLVED ORGANIC CARBON TRENDS RESULTING FROM CHANGES IN ATMOSPHERIC DEPOSITION CHEMISTRY

    EPA Science Inventory

    Several hypotheses have been proposed to explain recent, widespread increases in concentrations of dissolved organic carbon (DOC) in the surface waters of glaciated landscapes across eastern North America and northern and central Europe. Some invoke anthropogenic forcing through ...

  7. Distal transport of dissolved hydrothermal iron in the deep South Pacific Ocean

    E-print Network

    Fitzsimmons, Jessica N.

    Until recently, hydrothermal vents were not considered to be an important source to the marine dissolved Fe (dFe) inventory because hydrothermal Fe was believed to precipitate quantitatively near the vent site. Based on ...

  8. Northern Gulf of Mexico estuarine coloured dissolved organic matter derived from MODIS data

    EPA Science Inventory

    Coloured dissolved organic matter (CDOM) is relevant for water quality management and may become an important measure to complement future water quality assessment programmes. An approach to derive CDOM using the Moderate Resolution Imaging Spectroradiometer (MODIS) was developed...

  9. Sulfamethazine sorption to soil: vegetative management, pH, and dissolved organic matter effects

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Elucidating veterinary antibiotic (VA) interactions with soil is important for assessing and mitigating possible environmental hazards. Objectives of this study were to investigate the effects of vegetative management, soil physical and chemical properties, and manure-derived dissolved organic matte...

  10. Effect of rheological properties of dissolved cellulose/microfibrillated cellulose blend suspensions on film forming.

    PubMed

    Saarikoski, Eve; Rissanen, Marja; Seppälä, Jukka

    2015-03-30

    Enzymatically treated cellulose was dissolved in a NaOH/ZnO solvent system and mixed together with microfibrillated cellulose (MFC) in order to find the threshold in which MFC fibers form a percolation network within the dissolved cellulose solution and in order to improve the properties of regenerated cellulose films. In the aqueous state, correlations between the rheological properties of dissolved cellulose/MFC blend suspensions and MFC fiber concentrations were investigated and rationalized. In addition, rheological properties of diluted MFC suspensions were characterized and a correlation with NaOH concentration was found, thus partly explaining the flow properties of dissolved cellulose/MFC blend suspensions. Finally, based on results from Dynamic Mechanical Analysis (DMA), MFC addition had strengthening/plasticizing effect on regenerated cellulose films if low concentrations of MFC, below the percolation threshold (5.5-6 wt%, corresponding to 0.16-0.18 wt% of MFC in the blend suspensions), were used. PMID:25563945

  11. CHROMOPHORIC DISSOLVED ORGANIC MATTER (CDOM) SOURCE CHARACTERIZATION IN THE LOUISIANA BIGHT

    EPA Science Inventory

    Chromophoric dissolved organic matter (CDOM) in the Mississippi plume region may have several distinct sources: riverine (terrestrial soils), wetland (terrestrial plants), biological production (phytoplankton, zooplankton, microbial), and sediments. Complex mixing, photodegradati...

  12. Influence of light, temperature and salinity on dissolved organic carbon exudation rates in Zostera marina L.

    EPA Science Inventory

    Seagrass carbon budgets provide valuable insight on the minimum requirements needed to maintain this valuable resource. Carbon budgets are a balance between C fixation, storage and loss rates, most of which are well characterized. However, relatively few measurements of dissolv...

  13. COEUR D'ALENE LAKE, IDAHO. HYPOLIMNETIC CONCENTRATIONS OF DISSOLVED OXYGEN, NUTRIENTS, AND TRACE ELEMENTS, 1987

    EPA Science Inventory

    A reconnaissance study of Coeur dAlene Lake, Idaho (17010303) done from May through November 1987 assessed water quality throughout the lake. Particular emphasis was on hypolimnetic concentrations of dissolved oxygen, nutrients, and trace elements. Study results enabled refinem...

  14. Sources and Fates of Dissolved Organic Carbon in Rural and Urban Watersheds in Brazos County, Texas 

    E-print Network

    Cioce, Danielle

    2012-10-19

    quality. Dissolved organic matter is crucial in aquatic systems as it provides an energy source for biota and protects aquatic life from UV light (Williamson and Zagarese 1994; Leenheer and Croue 2003). It is also responsible for the complexation...

  15. Influence of natural dissolved organic matter (DOM) on acute and chronic toxicity of the pesticides chlorothalonil,

    E-print Network

    Decho, Alan

    as for a wide variety of macro- and meiofauna (Mitsch and Gosselink, 2000). Estuarine salt marshes are among (Mitsch and Gosselink, 2000). These ecosystems are rich in dissolved organic matter (DOM) (Dafner

  16. Interaction of temperature, dissolved oxygen and feed energy on ecophysiological performance of juvenile red drum 

    E-print Network

    Fontaine, Lance Pierre

    2008-10-10

    . I performed indoor-tank and outdoor-pond experiments, in conjunction with automa ted respirometry and ecophysiological modeling, to assess interacting effects of temperature, dissolved-oxygen concentration (DO) and feed energy density on survival...

  17. Abiotic effects on effluent dissolved organic nitrogen along an estuarine transect.

    PubMed

    Funkey, Carolina P; Latour, Robert J; Bronk, Deborah A

    2015-03-01

    Biological nutrient removal is a process commonly used in water resource recovery facilities to reduce dissolved inorganic nitrogen (DIN) concentrations in effluent; this process is less effective at removing all of the effluent dissolved organic nitrogen (EDON). The goal of this study was to investigate the fate of EDON after it undergoes the disinfection process and enters receiving waters. The authors quantified the abiotic effects of effluent exposure to sunlight, increased salinity, and a combination of the two factors. Effluent dissolved organic nitrogen showed significant breakdown during the disinfection process (UV and chlorine) and when exposed to sunlight and increasing salinity. Approximately 7% of the EDON was transformed to DIN and dissolved primary amines after exposure to 9 hours of sunlight and a salinity increase from 0 to 33. The production of DIN and primary amines should be taken into account when considering sources of labile nitrogen to aquatic ecosystems. PMID:25842537

  18. Evaluation of sampling strategies to characterize dissolved oxygen conditions in northern Gulf of Mexico estuaries

    SciTech Connect

    Summers, J.K.; Engle, V.D.

    1993-01-01

    Dissolved oxygen was continuously monitored in eight sites of northern Gulf of Mexico estuaries in August, 1990. Monte Carlo analyses on subsamples of the data were used to evaluate several commonly used monitoring strategies. Monitoring strategies which involve single point sampling of dissolved oxygen may often misclassify an estuary as having good water quality. In the case of shallow, often well-mixed estuaries that experience diurnal cycles, such monitoring often does not occur at night, during the time of lowest dissolved oxygen concentration. The authors' objective was to determine the minimum sampling effort required to correctly classify a site in terms of the observed frequency of hypoxia. Tests concluded that the most successful classification strategy used the minimum dissolved oxygen concentration from a continuously sampled 24-hour period. (Copyright (c) 199e Kluwer Academic Publishers.)

  19. Photobleaching Kinetics of Chromophoric Dissolved Organic Matter Derived from Mangrove Leaf Litter and Floating Sargassum Colonies

    EPA Science Inventory

    We examined the photoreactivity of chromophoric dissolved organic matter (CDOM) derived from Rhizophora mangle (red mangrove) leaf litter and floating Sargassum colonies as these marine plants can be important contributors to coastal and open ocean CDOM pools, respectively. Mangr...

  20. Closely related phytoplankton species produce similar suites of dissolved organic matter

    E-print Network

    Becker, Jamie William

    Production of dissolved organic matter (DOM) by marine phytoplankton supplies the majority of organic substrate consumed by heterotrophic bacterioplankton in the sea. This production and subsequent consumption converts a ...