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1

Organic iodine removal from simulated dissolver off-gas streams using partially exchanged silver mordenite  

Microsoft Academic Search

The removal of methyl iodide by adsorption onto silver mordenite was studied using a simulated off-gas from the fuel dissolution step of a nuclear fuel reprocessing plant. The methyl iodide adsorption of partially exchanged silver mordenite was examined for the effects of NO\\/sub x\\/, humidity, filter temperature, and degree of silver exchange. Partially exchanged silver mordenite, in general, achieved significantly

Jubin

1982-01-01

2

Organic iodine removal from simulated dissolver off-gas streams using silver-exchanged mordenite  

Microsoft Academic Search

The removal of methyl iodide by absorption onto silver mordenite was studied using a simulated off-gas from the fuel dissolution step of a nuclear fuel reprocessing plant. The methyl iodide absorption of silver mordenite was examined for the effects of NO\\/sub x\\/, humidity, iodine concentration, filter temperature, and filter pretreatment. The highest iodine loading achieved in these tests has been

Jubin

1980-01-01

3

Organic iodine removal from simulated dissolver off-gas systems utilizing silver-exchanged mordenite  

Microsoft Academic Search

The removal of methyl iodide by adsorption onto silver mordenite was studied using a simulated off-gas from the fuel dissolution step of a nuclear fuel reprocessing plant. The adsorption of methyl iodide on silver mordenite was examined for the effect of NO\\/sub x\\/, humidity, iodine concentration, filter temperature, silver loadings and filter pretreatment. The highest iodine loading achieved in these

Jubin

1981-01-01

4

Organic iodine removal from simulated dissolver off-gas streams using silver-exchanged mordenite  

SciTech Connect

The removal of methyl iodide by absorption onto silver mordenite was studied using a simulated off-gas from the fuel dissolution step of a nuclear fuel reprocessing plant. The methyl iodide absorption of silver mordenite was examined for the effects of NO/sub x/, humidity, iodine concentration, filter temperature, and filter pretreatment. The highest iodine loading achieved in these tests has been 34 mg CH/sub 3/I per g of substrate, approximately five times less than the elemental iodine loadings. Results indicate that a filter operating at a temperature of 150/sup 0/C obtained higher iodine loadings than a similar filter operating at 100/sup 0/C. Pretreatment of the sorbent bed with hydrogen, rather than dry air, at a temperature of 200/sup 0/C also improved the loading. Variations in the methyl iodide concentration had minimal effects on the overall loading. Filters exposed to moist air streams attained higher loadings than those in contact with dry air. A study of the regeneration characteristics of silver mordenite indicates limited adsorbent capacity after complete removal of the iodine with 4% hydrogen in the regeneration gas stream at 500/sup 0/C. 9 figures.

Jubin, R.T.

1980-01-01

5

Organic iodine removal from simulated dissolver off-gas streams using partially exchanged silver mordenite  

SciTech Connect

The removal of methyl iodide by adsorption onto silver mordenite was studied using a simulated off-gas from the fuel dissolution step of a nuclear fuel reprocessing plant. The methyl iodide adsorption of partially exchanged silver mordenite was examined for the effects of NO/sub x/, humidity, filter temperature, and degree of silver exchange. Partially exchanged silver mordenite, in general, achieved significantly higher silver utilizations than the fully exchanged material. Silver utilizations of > 95% were achieved, assuming the formation of AgI. The experimental results indicate that CH/sub 3/I loadings increase proportionally with silver loading up to 5 wt % silver and then appear to level off. Tests conducted to determine the effect of temperature on the loading showed higher loadings at 200/sup 0/C than at either 150 or 250/sup 0/C. The presence of NO, NO/sub 2/, and H/sub 2/O vapor showed negligible effects on the loading of CH/sub 3/I. In contrast to iodine loaded onto fully exchanged silver mordenite, the iodine loaded onto the partially exchanged silver mordenite could not be stripped by either 4.5% hydrogen or 100% hydrogen at temperatures up to 500/sup 0/C. A study of the regeneration characteristics of fully exchanged silver mordenite indicates a decreased adsorbent capacity after complete removal of the iodine with 4.5% hydrogen in the regeneration gas stream at 500/sup 0/C. The loss of adsorbent capacity was much higher for silver mordenite regenerated in a stainless steel filter housing than in a glass filter housing. A cost evaluation for the use of the partially exchanged silver mordenite shows that the cost of the silver mordenite on a once-through basis is < $10/h of operation for a 0.5-t/d reprocessing plant.

Jubin, R.T.

1982-01-01

6

Organic iodine removal from simulated dissolver off-gas systems utilizing silver-exchanged mordenite  

SciTech Connect

The removal of methyl iodide by adsorption onto silver mordenite was studied using a simulated off-gas from the fuel dissolution step of a nuclear fuel reprocessing plant. The adsorption of methyl iodide on silver mordenite was examined for the effect of NO/sub x/, humidity, iodine concentration, filter temperature, silver loadings and filter pretreatment. The highest iodine loading achieved in these tests was 142 mg CH/sub 3/I per g of substrate on fully exchanged zeolite, approximately the same as elemental iodine loadings. A filter using fully exchanged silver mordenite operating at 200/sup 0/C obtained higher iodine loadings than a similar filter operating at 150/sup 0/C. Pretreatment of the sorbent bed with hydrogen rather than dry air, at a temperature of 200/sup 0/C, also improved the loading. Variations in the methyl iodide concentration had minimal effects on the overall loading. Filters exposed to moist air streams attained higher loadings than those in contact with dry air. Partially exchanged silver mordenite achieved higher silver utilizations than the fully exchanged material. The partially exchanged mordenite also achieved higher loadings at 200/sup 0/C than at 250/sup 0/C. The iodine loaded onto these beds was not stripped at 500/sup 0/C by either 4.5% hydrogen or 100% hydrogen; however, the iodine could be removed by air at 500/sup 0/C, and the bed could be reloaded. A study of the regeneration characteristics of fully exchanged silver mordenite indicates limited adsorbent capacity after complete removal of the iodine with 4.5% hydrogen in the regeneration gas stream at 500/sup 0/C. The loss of adsorbent capacity is much higher for silver mordenite regenerated in a stainless steel filter housing than in a glass filter housing.

Jubin, R.T.

1981-01-01

7

Off-gas Adsorption Model and Simulation - OSPREY  

SciTech Connect

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.

Veronica J Rutledge

2013-10-01

8

Off-gas adsorption model and simulation - OSPREY  

SciTech Connect

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

Rutledge, V.J. [Idaho National Laboratory, P. O. Box 1625, Idaho Falls, ID (United States)

2013-07-01

9

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

SciTech Connect

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.

Jubin, Robert Thomas [ORNL

2009-06-01

10

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

SciTech Connect

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

Saito, H.H.

2001-03-28

11

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

SciTech Connect

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

Calloway, T.B. Jr.

2003-10-23

12

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

SciTech Connect

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

Yuan Zhang; Jin-hu Wu; Dong-ke Zhang [Chinese Academy of Sciences, Taiyuan (China). Institute of Coal Chemistry

2008-03-15

13

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

SciTech Connect

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

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

2002-08-01

14

Test Plan to Demonstrate Removal of Iodine and Tritium from Simulated Nuclear Fuel Recycle Plant Off-gas Streams using Adsorption Processes  

SciTech Connect

This letter documents the completion of the FCR&D Level 4 milestone for the Sigma Team – Off-Gas - ORNL work package (FT-14OR031202), “Co-absorption studies - Design system complete/test plan complete” (M4FT-14OR0312022), due November 15, 2013. The objective of this test plan is to describe research that will determine the effectiveness of silver mordenite and molecular sieve beds to remove iodine and water (tritium) from off-gas streams arising from used nuclear fuel recycling processes, and to demonstrate that the iodine and water can be recovered separately from one another.

Bruffey, Stephanie H. [ORNL] [ORNL; Spencer, Barry B. [ORNL] [ORNL; Jubin, Robert Thomas [ORNL] [ORNL

2013-12-11

15

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

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

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

2011-12-29

16

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

SciTech Connect

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

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

1996-05-02

17

Off gas film cooler cleaner  

SciTech Connect

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

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

1995-12-31

18

Glass melter off-gas system  

DOEpatents

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

Jantzen, Carol M. (Aiken, SC)

1997-01-01

19

Dynamic Absorption Model for Off-Gas Separation.  

National Technical Information Service (NTIS)

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...

V. J. Rutledge

2011-01-01

20

Dissolved oxygen convection and diffusion numerical simulation of stokes wave  

Microsoft Academic Search

In order to study the reoxygenation of the coastal wave, the two-dimensional renormalized-group (2-D RNG) k-epsilon ( ?-? ) mathematical model and Volume of Fluid (VOF) method are employed to compute the motion of a stokes wave. Dissolved oxygen convection and diffusion model is established to simulate the dissolved oxygen concentration with user defined scalar method. The computational results of

Zegao Yin; Lianchun Zhang; Xianwei Cao; Le Wang; Dongsheng Cheng

2011-01-01

21

Molecular simulation of a model of dissolved organic matter  

Microsoft Academic Search

A series of atomistic simulations was performed to assess the ability of the Schulten dissolved organic matter (DOM) molecule, a well-established model humic molecule, to reproduce the physical and chemical behavior of natural humic substances. The unhydrated DOM molecule had a bulk density value appropriate to humic matter, but its Hildebrand solubility parameter was lower than the range of current

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

2004-01-01

22

Cold Dissolved Saltcake Waste Simulant Development, Preparation, and Analysis  

SciTech Connect

CH2M Hill Hanford Group, Inc. is identifying and developing supplemental process technologies to accelerate the Hanford tank waste cleanup mission. Bulk vitrification, containerized grout, and steam reforming are three technologies under consideration for treatment of the radioactive saltcake wastes in 68 single-shell tanks. To support development and testing of these technologies, Pacific Northwest National Laboratory (PNNL) was tasked with developing a cold dissolved saltcake simulant formulation to be representative of an actual saltcake waste stream, preparing a 25-L batch of the simulant, and analyzing the composition of the batch to assure conformance to formulation targets. Lacking a defined composition for dissolved actual saltcake waste, PNNL used available tank waste composition information and an equilibrium chemistry model (Environmental Simulation Program, ESP) to predict the concentrations of analytes in solution. Observations of insoluble solids in initial laboratory preparations for the model predicted formulation prompted minor modifications in the concentration of phosphate and silicon in the final simulant formulation. The analytical results for the 25-L simulant batch agree within the expected measurement accuracy (~10%) of the target concentrations and are highly consistent for replicate measurements, with a few minor exceptions. The instrumental analyses indicate that the batch of solution adequately reflects the as-formulated simulant composition. In parallel with the simulant development effort, a nominally 5-M (molar) sodium actual sodium waste solution was prepared at the Hanford site from a limited number of tank waste samples. Since this actual waste solution was also to be used for testing of the supplemental treatment technologies, the modeled simulant formulation was predicated on the composite of waste samples used to prepare it. Subsequently, the actual waste solution was filtered and pretreated to remove radioactive cesium at PNNL and then analyzed using the same instrumentation and procedures applied to the simulant samples. The overall agreement of measured simulant and actual waste solution compositions is better than 10% for the most concentrated species including sodium, nitrate, hydroxide, carbonate, and nitrite. While the magnitude of the relative difference in the simulant and actual waste composition is large (>20% difference) for a few analytes (aluminum, chromium, fluoride, potassium, and total organic carbon), the absolute differences in concentration are in general not appreciable. Our evaluation is that these differences in simulant and actual waste solutions should have a negligible impact on supplemental treatment process testing.

Rassat, Scot D. (BATTELLE (PACIFIC NW LAB)); Mahoney, Lenna A. (BATTELLE (PACIFIC NW LAB)); Russell, Renee L. (BATTELLE (PACIFIC NW LAB)); Bryan, Samuel A. (BATTELLE (PACIFIC NW LAB)); Sell, Rachel L. (BATTELLE (PACIFIC NW LAB))

2003-02-25

23

Biological nitrification process simulation in groundwater with dissolved oxygen controller  

NASA Astrophysics Data System (ADS)

Nowadays groundwater contamination by nitrogenous fertilizer is a globally growing problem, but groundwater always serves as an important water source, especially in rural area. In order to tackle this problem, biological nitrification and denitrification process has been widely used for removal of nitrogenous pollutants from polluted water. To improve removal efficiency, the dissolved oxygen (DO) controller is presented. And the control strategies for the activated sludge process have been developed and evaluated by simulation. The results also showed that the DO controller will be applied widely in the control and management of the decentralization water treatment.

Zuo, Jinlong

2009-07-01

24

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

USGS Publications Warehouse

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

Galloway, Joel M.; Green, W. Reed

2003-01-01

25

Cold Dissolved Saltcake Waste Simulant Development, Preparation, and Analysis  

SciTech Connect

CH2M HILL Hanford Group, Inc. is identifying and developing supplemental process technologies to accelerate the Hanford tank waste cleanup mission. Bulk vitrification, containerized grout, and steam reforming are three technologies under consideration for treatment of the radioactive saltcake wastes in 68 single-shell tanks. To support development and testing of these technologies, Pacific Northwest National Laboratory (PNNL) was tasked with developing a cold dissolved saltcake simulant formulation to be representative of an actual saltcake waste stream, preparing 25- and 100-L batches of the simulant, and analyzing the composition of the batches to ensure conformance to formulation targets. Lacking a defined composition for dissolved actual saltcake waste, PNNL used available tank waste composition information and an equilibrium chemistry model (Environmental Simulation Program [ESP{trademark}]) to predict the concentrations of analytes in solution. Observations of insoluble solids in initial laboratory preparations for the model-predicted formulation prompted reductions in the concentration of phosphate and silicon in the final simulant formulation. The analytical results for the 25- and 100-L simulant batches, prepared by an outside vendor to PNNL specifications, agree within the expected measurement accuracy ({approx}10%) of the target concentrations and are highly consistent for replicate measurements, with a few minor exceptions. In parallel with the production of the 2nd simulant batch (100-L), a 1-L laboratory control sample of the same formulation was carefully prepared at PNNL to serve as an analytical standard. The instrumental analyses indicate that the vendor prepared batches of solution adequately reflect the as-formulated simulant composition. In parallel with the simulant development effort, a nominal 5-M (molar) sodium actual waste solution was prepared at the Hanford Site from a limited number of tank waste samples. Because this actual waste solution w as also to be used for testing the supplemental treatment technologies, the modeled simulant formulation was predicated on the composite of waste samples used to prepare it. Subsequently, the actual waste solution was filtered and pretreated to remove radioactive cesium at PNNL and then analyzed using the same instrumentation and procedures applied to the simulant samples. The overall agreement of measured simulant and actual waste solution compositions is better than {+-}10% for the most concentrated species including sodium, nitrate, hydroxide, carbonate, and nitrite. While the magnitude of the relative difference in the simulant and actual waste composition is large (>20% difference) for a few analytes (aluminum, chromium, fluoride, potassium, and total organic carbon), the absolute differences in concentration are in general not appreciable. Our evaluation is that these differences in simulant and actual waste solutions should have a negligible impact on bulk vitrification and containerized grout process testing, while the impact of the low aluminum concentration on steam reforming is yet to be determined.

Rassat, Scot D.; Mahoney, Lenna A.; Russell, Renee L.; Bryan, Samuel A.; Sell, Rachel L.

2003-05-13

26

Numerical simulation of dissolved silica in the San Fancisco Bay  

USGS Publications Warehouse

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.

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

1978-01-01

27

Adsorption modeling for off-gas treatment  

SciTech Connect

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

Ladshaw, A.; Sharma, K.; Yiacoumi, S.; Tsouris, C. [Georgia Institute of Technology, Atlanta, GA 30332-0459 (United States); De Paoli, D.W. [Oak Ridge National Laboratory: Oak Ridge, TN 37831-6181 (United States)

2013-07-01

28

Simulation of thermal\\/dissolved oxygen habitat for fishes in lakes under different climate scenarios  

Microsoft Academic Search

Fish habitat is strongly constrained by water temperature and available dissolved oxygen (DO). Thermal\\/dissolved oxygen habitat for cold-water fish in small lakes was therefore determined from simulated daily water temperature and dissolved oxygen profiles. Twenty-seven types of lakes were simulated with past (1961–1979) climate conditions observed at 209 weather stations in the USA, and with a 2×CO2 climate scenario that

Xing Fang; Heinz G Stefan; John G Eaton; J. Howard McCormick; Shoeb R Alam

2004-01-01

29

Simulation of thermal\\/dissolved oxygen habitat for fishes in lakes under different climate scenarios  

Microsoft Academic Search

Fish habitat is strongly constrained by water temperature and dissolved oxygen. Thermal\\/dissolved oxygen habitat for warm-water fish in small lakes was therefore determined from simulated daily water temperature and dissolved oxygen profiles. Twenty-seven types of lakes were simulated with past (1961–1979) climate conditions observed at 209 weather stations in the contiguous USA as input, and with a 2×CO2 climate scenario

Xing Fang; Heinz G Stefan; John G Eaton; J. Howard McCormick; Shoeb R Alam

2004-01-01

30

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

SciTech Connect

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.

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

2013-09-01

31

Simulation Analysis for HB-Line Dissolver Mixing  

SciTech Connect

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.

Lee, S

2006-03-22

32

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...

33

Simulation of dissolved oxygen profiles in a transparent, dimictic lake  

Microsoft Academic Search

Thrush Lake is a small, highly transparent lake in northeastern Minnesota. From 1986 to 199 1, vertical profiles of water temperature, dissolved oxygen, chlorophyll a concentration, underwater light irradiance, and Secchi depths were measured at monthly intervals during the ice-free period. Average Secchi depth was 7.5 m. Metalimnetic oxygen maxima were observed every summer. The oxygen peaks were related to

HEINZ G. STEFAN; XING FANG; DAVID WRIGHT; JOHN G. EATON; J. HOWARD MCCORMICK

1995-01-01

34

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

Microsoft Academic Search

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,

A. S. Choi; D. C. Iverson

1996-01-01

35

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

USGS Publications Warehouse

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

Haggard, Brian; Green, W. Reed

2002-01-01

36

CHARACTERIZATION OF DWPF MELTER OFF-GAS QUENCHER SAMPLE  

SciTech Connect

The Savannah River National Laboratory (SRNL) recently received a deposit sample from the Melter Primary Off Gas System (POG) of the Defense Waste Processing Facility (DWPF). This sample was composed of material that had been collected while the quencher was in operation January 27, 2011 through March 31, 2011. DWPF requested, through a technical assistance request, characterization of the melter off-gas deposits by x-ray diffraction (XRD), scanning electron microscopy (SEM), and chemical analysis. The purpose of the Melter Off-Gas System is to reduce the amount of radioactive particles and mercury in the gases vented to the atmosphere. Gases emitted from the melter pass through the primary film cooler, quencher, Off-Gas Condensate Tank (OGCT), Steam Atomized Scrubbers (SAS), a condenser, a high efficiency mist eliminator, and a high efficiency particulate air filter, before being vented to the Process Vessel Vent System. The film coolers cool the gases leaving the melter vapor space from {approx}750 C to {approx}375 C, by introducing air and steam to the flow. In the next step, the quencher cools the gas to about 60 C by bringing the condensate from the OGCT in contact with the effluent (Figure 1). Most of the steam in the effluent is then condensed and the melter vapor space pressure is reduced. The purpose of the OGCT is to collect and store the condensate formed during the melter operation. Condensate from the OGCT is circulated to the SAS and atomized with steam. This atomized condensate is mixed with the off-gas to wet and join the particulate which is then removed in the cyclone. The next stage incorporates a chilled water condenser which separates the vapors and elemental mercury from the off-gas steam. Primary off-gas deposit samples from the DWPF melter have previously been analyzed. In 2003, samples from just past the film cooler, from the inlet of the quencher and inside the quencher were analyzed at SRNL. It was determined that the samples were a mixture of sludge and glass frit. The major component was Si along with Fe, Al, and other elements in the radioactive waste being processed. The deposits analyzed also contained U-235 fission products and actinide elements. Prior to that, deposits in the off-gas system in the DWPF nonradioactive half scale melter and the one-tenth scale integrated DWPF melter system were analyzed and determined to be mixtures of alkali rich chlorides, sulfates, borates, and fluorides entrained with iron oxides, spinels and frit particles formed by vapor-phase transport and condensation. Additional work was performed in 2007 in which researchers similarly found the deposits to be a combination of sludge and frit particles.

Newell, J.

2011-11-14

37

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

USGS Publications Warehouse

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

Galloway, Joel M.; Green, W. Reed

2002-01-01

38

In-place testing of off-gas iodine filters  

Microsoft Academic Search

At the Idaho National Engineering Laboratory, both charcoal and silver zeolite (AgX) filters are used for radioactive iodine off-gas cleanup of reactor systems. These filters are used in facilities which are conducting research in the areas of reactor fuel failure, reactor fuel inspection, and loss of fluids from reactor vessels. Iodine retention efficiency testing of these filters is dictated by

S. W. Duce; J. W. Tkachyk; B. G. Motes

1980-01-01

39

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...

40

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

SciTech Connect

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.

Nick Soelberg; Jay Roach

2009-01-01

41

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

EPA Science Inventory

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

42

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

EPA Science Inventory

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

43

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 ...

44

A numerical simulation study of dissolved organic carbon accumulation in the northern Adriatic Sea  

Microsoft Academic Search

A mechanistic explanation for the accumulation of dissolved organic carbon (DOC), observed in coastal seas such as the Northern Adriatic Sea, is proposed here on the basis of numerical simulations of the marine ecosystem dynamics carried out with a coupled biogeochemical-circulation model. The biogeochemical model is based on the European Regional Seas Ecosystem Model (ERSEM) upgraded with a more detailed

L. Polimene; N. Pinardi; M. Zavatarelli; J. I. Allen; M. Giani; M. Vichi

2007-01-01

45

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

Microsoft Academic Search

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

Xing Fang; Heinz G. Stefan

1997-01-01

46

Microwave off-gas treatment apparatus and process  

DOEpatents

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

Schulz, Rebecca L. (Aiken, SC); Clark, David E. (Gainesville, FL); Wicks, George G. (North Aiken, SC)

2003-01-01

47

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

USGS Publications Warehouse

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

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

2003-01-01

48

Proposed Strategies for DWPF Melter Off-Gas Surge Control  

SciTech Connect

Off-gas surging is inherent to the operation of slurry-fed melters. Although the melter design and the feed chemistry are both known to significantly affect off-gas surging, the frequency and intensity of surges are in essence unpredictable. In typical off-gas surges, both condensable and non condensable flows spike simultaneously. Condensable or steam surges have been observed to occur as the boiling water layer occasionally falls into the crevices of the cold cap or flows over the edges of the cold cap, thereby coming in contact with the melt surface. The resulting steam surges can pressurize the melter considerably and, therefore, are responsible for the bulk of pressure transients that propagate throughout the off-gas system. The non condensable surges occur as the calcine gases that have been accumulating within the cold cap finally build up enough pressure to be released through the temporary openings of the cold cap. The analysis of off-gas data has shown that over 90 of the gas released during a surge is due to steam.1 Therefore, it is essential to have a large inventory of water in the cold cap for any significant pressure spikes to occur. With the Melter 2 vapor space temperature typically running at 720C, the water layer in the cold cap will quickly evaporate once the feeding stops, and the potential for any large pressure spikes should practically cease to exist. The analysis also showed that large pressure spikes well above 2 inches H2O cannot occur under the steam surge scenarios described above. More severe conditions should prevail and one such condition would be that the feed materials form a mound with a growing lake on top, while the melt below remains very fluidic due to its low viscosity, thus resulting in greater movements both in the lateral as well as vertical directions. Once the mound begins to grow, its rate should accelerate, since the heat transfer rate to the upper regions of the cold cap is inversely proportional to the cold cap thickness. Then, when the mound reaches some critical mass, it may begin sink into the bulk melt or tip over, thereby creating a condition almost like a steam explosion.

CHOI, ALEXANDERS.

2004-06-01

49

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

SciTech Connect

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.

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

1984-06-01

50

Simulations of underwater plumes of dissolved oil in the Gulf of Mexico  

NASA Astrophysics Data System (ADS)

A simple model of the temperature-dependent biological decay of dissolved oil is embedded in an ocean-climate model and used to simulate underwater plumes of dissolved and suspended oil originating from a point source in the northern Gulf of Mexico, with an upper-bound supply rate estimated from the contemporary analysis of the Deepwater Horizon blowout. The behavior of plumes at different depths is found to be determined by the combination of sheared current strength and the vertical profile of decay rate. For all plume scenarios, toxic levels of dissolved oil remain confined to the northern Gulf of Mexico, and abate within weeks after the spill stops. An estimate of oxygen consumption due to microbial oxidation of hydrocarbons suggests that a deep plume of hydrocarbons could lead to localized regions of prolonged hypoxia near the source, but only when oxidation of methane is included.

Adcroft, Alistair; Hallberg, Robert; Dunne, John P.; Samuels, Bonita L.; Galt, J. A.; Barker, Christopher H.; Payton, Debra

2010-09-01

51

Model simulations of dissolved oxygen characteristics of Minnesota lakes: Past and future  

Microsoft Academic Search

A deterministic, one-dimensional, unsteady numerical model has been developed, tested, and applied to simulate mean daily\\u000a dissolved oxygen (DO) characteristics in 27 lake classes in the state of Minnesota. Reaeration and photosynthesis are the\\u000a oxygen sources, while respiration, sedimentary, and biochemical water column oxygen demand are the sinks of oxygen in the\\u000a model. The lake classes are differentiated by surface

Heinz G. Stefan; Xing Fang

1994-01-01

52

A Review of Public Domain Water Quality Models for Simulating Dissolved Oxygen in Rivers and Streams  

Microsoft Academic Search

The review discusses six major public domain water quality models currently available for rivers and streams. These major\\u000a models, which differ greatly in terms of processes they represent, data inputs requirements, assumptions, modeling capability,\\u000a their strengths and weaknesses, could yield useful results if appropriately selected for the desired purposes. The public\\u000a domain models, which are most suitable for simulating dissolved

Prakash R. Kannel; Sushil R. Kanel; Seockheon Lee; Young-Soo Lee; Thian Y. Gan

2011-01-01

53

Comparative simulations of dissolved organic matter cycling in idealized oceanic, coastal, and estuarine surface waters  

NASA Astrophysics Data System (ADS)

In this paper we used a steady-state ecosystem model that simulates both dissolved organic carbon (DOC) and nitrogen (DON) cycling to study how the planktonic community structure, nutrient availability, and dissolved organic matter (DOM) loading affect these cycles in idealized oceanic, coastal, and estuarine surface waters. The model was able to reproduce DOM and planktonic biomass distributions, uptake rates, and production rates (including DOM) that fell within ranges reported for oceanic, coastal, and estuarine systems. Using a sensitivity analysis we show that DOM cycling was intricately tied to the biomass concentration, distribution, and productivity of plankton. The efficiency of nutrient remineralization and the availability of inflowing nutrients and DON also played a large role in DOM cycling. In these simulations the largest autochthonous source of DOC was always phytoplankton exudation while important sources of DON varied considerably. In the oceanic simulations heterotrophic bacteria were particularly important for mediating DOM cycling because they were the primary agents that controlled nutrient recycling and supply (i.e., strong bottom-up control). In contrast, in the estuarine simulations mortality (mainly from grazing and viral lysis) had the most influence on DOM production. However, DOM cycling was generally less dependent on interactions between plankton in the estuarine case because of high nutrient and DOM loading. The coastal simulations were somewhere in between. In all simulations competition between different size classes of phytoplankton also played an important role in DOM cycling.

Keller, David P.; Hood, Raleigh R.

2013-01-01

54

Cooler and particulate separator for an off-gas stack  

DOEpatents

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

Wright, G.T.

1991-04-08

55

Process for off-gas particulate removal and apparatus therefor  

DOEpatents

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

Carl, D.E.

1997-10-21

56

Process for off-gas particulate removal and apparatus therefor  

DOEpatents

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

Carl, Daniel E. (Orchard Park, NY)

1997-01-01

57

Role of dissolved salts in thermophoresis of DNA: Lattice-Boltzmann-based simulations  

NASA Astrophysics Data System (ADS)

We use a lattice Boltzmann based Brownian dynamics simulation to investigate the dependence of DNA thermophoresis on its interaction with dissolved salts. We find the thermal diffusion coefficient DT depends on the molecule size, in contrast with previous simulations without electrostatics. The measured ST also depends on the Debye length. This suggests thermophoresis of DNA is influenced by the electrostatic interactions between the polymer beads and the salt ions. However, when electrostatic forces are weak, DNA thermophoresis is not found, suggesting that other repulsive forces such as the excluded volume force prevent thermal migration.

Hammack, Audrey; Chen, Yeng-Long; Pearce, Jennifer Kreft

2011-03-01

58

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

USGS Publications Warehouse

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.

Robertson, Dale M.

2000-01-01

59

Method for the recovery of clean pyrolysis off-gas and a rotary recycling means therefor  

Microsoft Academic Search

A method and apparatus for stripping entrained organic vapor and solid particulate matter from a pyrolytic off-gas stream is disclosed. The off-gas is introduced at the top of a conical chamber having a variable speed ''squirrel cage'' rotor at its top. The wet, dirty, off-gas is drawn into the rotor from below and impinged upon the chamber walls which causes

L. W. Elston; D. R. Hurst

1981-01-01

60

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

SciTech Connect

AREVA Federal Services (AFS) is performing a multi-year, multi-phase Advanced Remediation Technologies (ART) project, sponsored by the U.S. Department of Energy (DOE), to evaluate the feasibility and benefits of replacing the existing joule-heated melter (JHM) used to treat high level waste (HLW) in the Defense Waste Processing Facility (DWPF) at the Savannah River Site with a cold crucible induction melter (CCIM). The AFS ART CCIM project includes several collaborators from AREVA subsidiaries, French companies, and DOE national laboratories. The Savannah River National Laboratory and the Commissariat a l’Energie Atomique (CEA) have performed laboratory-scale studies and testing to determine a suitable, high-waste-loading glass matrix. The Idaho National Laboratory (INL) and CEA are performing CCIM demonstrations at two different pilot scales to assess CCIM design and operation for treating SRS sludge wastes that are currently being treated in the DWPF. SGN is performing engineering studies to validate the feasibility of retrofitting CCIM technology into the DWPF Melter Cell. The long-term project plan includes more lab-testing, pilot- and large-scale demonstrations, and engineering activities to be performed during subsequent project phases. A simulant of the DWPF SB4 feed was successfully fed and melted in a small pilot-scale CCIM system during two test series. The OGSE tests provide initial results that (a) provide melter operating conditions while feeding a DWPF SB4 simulant feed, (b) determine the fate of feed organic and metal feed constituents and metals partitioning, and (c) characterize the melter off-gas source term to a downstream off-gas system. The INL CCIM test system was operated continuously for about 30 hours during the parametric test series, and for about 58 hours during the OGSE test. As the DWPF simulant feed was continuously fed to the melter, the glass level gradually increased until a portion of the molten glass was drained from the melter. The glass drain was operated periodically on-demand. A cold cap of unmelted feed was controlled by adjusting the feedrate and melter power levels to obtain the target molten glass temperatures with varying cold cap levels. Three test conditions were performed per the test plan, during which the melter was operated with a target melt temperature of either 1,250oC or 1,300oC, and with either a partial or complete cold cap of unmelted feed on top of the molten glass. Samples of all input and output streams including the starting glass, the simulant feed, the off-gas particulate matter, product glass, and deposits removed from the crucible and off-gas pipe after the test were collected for analysis.

Nick Soelberg

2009-04-01

61

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

PubMed

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

Miller Neilan, Rachael; Rose, Kenneth

2014-02-21

62

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

PubMed Central

Dissolved organic phosphorus (DOP) is increasingly recognized as an important phosphorus source to marine primary producers. Despite its importance, the production rate and fate of DOP is poorly understood. In this study, patterns of DOP production were evaluated by tracking the evolution of DOP during simulated phytoplankton blooms initiated with nutrient amended surface waters, relative to controls, from the Oregon (USA) coastal upwelling system. Nitrogen (N) and phosphorus (P) additions were used to decouple DOP production and hydrolysis by inducing or repressing, respectively, community alkaline phosphatase activity. In order to examine the progression of nutrient uptake and DOP production under upwelling versus relaxation conditions, two experiments were initiated with waters collected during upwelling events, and two with waters collected during relaxation events. Maximum [under (+P) conditions] and minimum [under (+N) conditions] DOP production rates were calculated and applied to in situ DOP levels to evaluate which end-member rate most closely approximates the in situ DOP production rate at the four study sites in this coastal system. Increases in DOP concentration occurred by day-5 in control treatments in all experiments. N treatments displayed increased chlorophyll a, increased alkaline phosphatase activity, and yielded lower net DOP production rates relative to controls, suggesting that DOP levels were depressed as a consequence of increased hydrolysis of bioavailable DOP substrates. Phosphorus additions resulted in a significant net production of DOP at all stations, but no increase in chlorophyll a relative to control treatments. The contrasting patterns in DOP production between treatments suggests that changes in the ambient dissolved inorganic nitrogen:dissolved inorganic phosphorus (DIN:DIP) ratio could exert profound control over DOP production rates in this system. Patterns of DOP production across the different experiments also suggest that bathymetry-driven differences in water residence times can influence DOP cycling. Taken together, these factors may impact the potential export of DOP to offshore ecosystems. PMID:22888326

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

2012-01-01

63

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

NASA Astrophysics Data System (ADS)

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.

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

2009-06-01

64

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

NASA Astrophysics Data System (ADS)

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

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

2007-05-01

65

A numerical simulation study of dissolved organic carbon accumulation in the northern Adriatic Sea  

NASA Astrophysics Data System (ADS)

A mechanistic explanation for the accumulation of dissolved organic carbon (DOC), observed in coastal seas such as the Northern Adriatic Sea, is proposed here on the basis of numerical simulations of the marine ecosystem dynamics carried out with a coupled biogeochemical-circulation model. The biogeochemical model is based on the European Regional Seas Ecosystem Model (ERSEM) upgraded with a more detailed representation of the DOC-bacteria interactions and resolving different level of DOC lability/refractivity. The circulation model is the Adriatic Sea implementation of the Princeton Ocean Model. The analysis of simulations confirms the important role of the Po river nutrient input on the ecosystem dynamics and highlights the presence of a strong across-shelf trophic gradient that, affecting the Bacterial Growth Efficiency (BGE), could be a key factor for the DOC accumulation. The simulations show the importance of circulation features in modulating the exchanges between areas having different trophic structure such as the western coastal strip, strongly influenced by the Po river runoff, and the open sea areas in the centre of the northern Adriatic sub-basin. The DOC produced in the high energy system of the Po runoff coastal strip, characterized by high BGE, is transported toward the open areas, which is a more oligotrophic environment with lower BGE. In this area the DOC turnover time is strongly increased giving rise to the DOC accumulation.

Polimene, L.; Pinardi, N.; Zavatarelli, M.; Allen, J. I.; Giani, M.; Vichi, M.

2007-03-01

66

Remediation on off-gas system deposits in a radioactive waste glass melter  

SciTech Connect

Since the early 1980`s, research glass melters have been used at the Savannah River Laboratory (SRL) to develop the reference vitrification process for immobilization of high level radioactive waste. One of the operating concerns for these melters has been the pluggage of the off-gas system with solid deposits. Samples of these deposits were analyzed to be mixture of alkali-rich chlorides, sulfates, borates, and fluorides with entrained Fe{sub 2}O{sub 3} spinel, and frit particles. The spatial distribution of these deposits throughout the off-gas system indicates that they form by vapor-phase transport and subsequently condensation. Condensation of the alkali-rich phases cements entrained particulates causing the off-gas line to plug. It is concluded that off-gas system pluggage can be effectively controlled by maintaining the off-gas velocity above 16 m/s, while maintaining the off-gas temperature as high as practical below the glass softening point. This paper summarizes the results of chemical and physical analyses of off-gas deposit samples from various melters at SRL. Recent design changes made to the Defense Waste Processing Facility (DWPF) at the Savannah River Site (SRS) to alleviate the pluggage problem are also discussed.

Jantzen, C.M.; Choi, A.S.; Randall, C.T.

1991-12-31

67

Remediation on off-gas system deposits in a radioactive waste glass melter  

SciTech Connect

Since the early 1980's, research glass melters have been used at the Savannah River Laboratory (SRL) to develop the reference vitrification process for immobilization of high level radioactive waste. One of the operating concerns for these melters has been the pluggage of the off-gas system with solid deposits. Samples of these deposits were analyzed to be mixture of alkali-rich chlorides, sulfates, borates, and fluorides with entrained Fe{sub 2}O{sub 3} spinel, and frit particles. The spatial distribution of these deposits throughout the off-gas system indicates that they form by vapor-phase transport and subsequently condensation. Condensation of the alkali-rich phases cements entrained particulates causing the off-gas line to plug. It is concluded that off-gas system pluggage can be effectively controlled by maintaining the off-gas velocity above 16 m/s, while maintaining the off-gas temperature as high as practical below the glass softening point. This paper summarizes the results of chemical and physical analyses of off-gas deposit samples from various melters at SRL. Recent design changes made to the Defense Waste Processing Facility (DWPF) at the Savannah River Site (SRS) to alleviate the pluggage problem are also discussed.

Jantzen, C.M.; Choi, A.S.; Randall, C.T.

1991-01-01

68

Numerical simulations of aquaculture dissolved waste transport in a coastal embayment  

NASA Astrophysics Data System (ADS)

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

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

2008-11-01

69

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

70

Determination of activated sludge biological activity using model corrected CO 2 off-gas data  

Microsoft Academic Search

Carbon dioxide (CO2) online off-gas monitoring is useful to detect changes in biological activity for activated sludge systems especially under limited oxygen conditions like under simultaneous nitrification–denitrification (SND) where respirometric measurements are not applicable. So far, the influence of the bicarbonate system on the liquid–gas transfer of CO2 prevented the wider use of off-gas CO2 for monitoring purposes in wastewater

Norbert Weissenbacher; Katharina Lenz; Susanne N. Mahnik; Bernhard Wett; Maria Fuerhacker

2007-01-01

71

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

USGS Publications Warehouse

Time-series plots of dissolved-oxygen concentrations were determined for various simulated hydrologic and point-source loading conditions along a free-flowing section of the Catawba River from Lake Wylie Dam to the headwaters of Fishing Creek Reservoir in South Carolina. The U.S. Geological Survey one-dimensional dynamic-flow model, BRANCH, was used to simulate hydrodynamic data for the Branched Lagrangian Transport Model. Waterquality data were used to calibrate the Branched Lagrangian Transport Model and included concentrations of nutrients, chlorophyll a, and biochemical oxygen demand in water samples collected during two synoptic sampling surveys at 10 sites along the main stem of the Catawba River and at 3 tributaries; and continuous water temperature and dissolved-oxygen concentrations measured at 5 locations along the main stem of the Catawba River. A sensitivity analysis of the simulated dissolved-oxygen concentrations to model coefficients and data inputs indicated that the simulated dissolved-oxygen concentrations were most sensitive to watertemperature boundary data due to the effect of temperature on reaction kinetics and the solubility of dissolved oxygen. Of the model coefficients, the simulated dissolved-oxygen concentration was most sensitive to the biological oxidation rate of nitrite to nitrate. To demonstrate the utility of the Branched Lagrangian Transport Model for the Catawba River, the model was used to simulate several water-quality scenarios to evaluate the effect on the 24-hour mean dissolved-oxygen concentrations at selected sites for August 24, 1996, as simulated during the model calibration period of August 23 27, 1996. The first scenario included three loading conditions of the major effluent discharges along the main stem of the Catawba River (1) current load (as sampled in August 1996); (2) no load (all point-source loads were removed from the main stem of the Catawba River; loads from the main tributaries were not removed); and (3) fully loaded (in accordance with South Carolina Department of Health and Environmental Control National Discharge Elimination System permits). Results indicate that the 24-hour mean and minimum dissolved-oxygen concentrations for August 24, 1996, changed from the no-load condition within a range of - 0.33 to 0.02 milligram per liter and - 0.48 to 0.00 milligram per liter, respectively. Fully permitted loading conditions changed the 24-hour mean and minimum dissolved-oxygen concentrations from - 0.88 to 0.04 milligram per liter and - 1.04 to 0.00 milligram per liter, respectively. A second scenario included the addition of a point-source discharge of 25 million gallons per day to the August 1996 calibration conditions. The discharge was added at S.C. Highway 5 or at a location near Culp Island (about 4 miles downstream from S.C. Highway 5) and had no significant effect on the daily mean and minimum dissolved-oxygen concentration. A third scenario evaluated the phosphorus loading into Fishing Creek Reservoir; four loading conditions of phosphorus into Catawba River were simulated. The four conditions included fully permitted and actual loading conditions, removal of all point sources from the Catawba River, and removal of all point and nonpoint sources from Sugar Creek. Removing the point-source inputs on the Catawba River and the point and nonpoint sources in Sugar Creek reduced the organic phosphorus and orthophosphate loadings to Fishing Creek Reservoir by 78 and 85 percent, respectively.

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

2003-01-01

72

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

NASA Astrophysics Data System (ADS)

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

Zhang, Litao; Wang, Jianqiu

2014-03-01

73

Cationic complexation with dissolved organic matter: Insights from molecular dynamics computer simulations and NMR spectroscopy  

NASA Astrophysics Data System (ADS)

Dissolved organic matter (DOM) is ubiquitous in soil and surface water and plays many important geochemical and environmental roles acting as a proton donor/acceptor and pH buffer and interacting with metal ions, minerals and organic species to form water-soluble and water-insoluble complexes of widely differing chemical and biological stabilities. There are strong correlations among the concentration of DOM and the speciation, solubility and toxicity of many trace metals in soil and water due to metal-DOM interaction. DOM can also significantly negatively affect the performance of nanofiltration and reverse osmosis membranes used industrially for water purification and desalination, being one of the major causes of a so-called `membrane bio- fouling'. The molecular scale mechanisms and dynamics of the DOM interactions with metals and membranes are, however, quite poorly understood. Methods of computational molecular modeling, combined with element- specific nuclear magnetic resonance (NMR) spectroscopy, can serve as highly effective tools to probe and quantify on a fundamental molecular level the DOM interactions with metal cations in aqueous solutions, and to develop predictive models of the molecular mechanisms responsible for the metal-DOM complexation in the environment. This paper presents the results of molecular dynamics (MD) computer simulations of the interaction of DOM with dissolved Na+, Cs+, Mg2+, and Ca2+. Na+ forms only very weak outer-sphere complexes with DOM. These results and the results of other recent molecular modeling efforts (e.g., Sutton et al., Environmental Toxicology and Chemistry, 24, 1902-1911, 2005), clearly indicate that both the structural and dynamic aspects of the cation-DOM complexation follow a simple trend in terms of the charge/size ratio for the ions. Due to the competition between ion hydration in bulk aqueous solution and adsorption of these cations by the negatively charged DOM functional groups (primarily carboxylate), larger ions of the same charge (Cs+ vs Na+, or Ca2+ vs Mg2+) have a stronger tendency for DOM association. However, for ions of approximately the same size, higher charge results in a stronger association with DOM. Thus, in contrast to Mg2+, Ca2+ forms strong inner-sphere complexes with DOM carboxylate groups, whereas the association of Na+ with DOM is even weaker than the outer-sphere metal- DOM complexing observed for Cs+. Taken together, these results support the idea of supramolecular, Ca- mediated DOM aggregation in aqueous environment. Cation-DOM binding occurs principally with carboxylate groups, and to a lesser extent with phenolic and other R-OH groups. The contributions of other DOM functional groups are minimal. The diffusional mobility of DOM-bound cations can decrease from ~20% (DOM- Na+ outer-sphere complex) to ~2000% (DOM-Ca2+ inner-sphere complex) compared with neat aqueous solutions (without DOM). The MD simulation results are in good agreement with NMR spectroscopic measurements for Cs-DOM solutions. The case of Cs+ complexation is particularly interesting, because Cs+ readily occurs as inner-sphere complexes on the surfaces of silica gel and many common soil minerals, including illite, kaolinite, and boehmite. The weaker interaction with DOM may be due to the occurence of relatively isolated carboxylic and phenolic groups on the DOM compared to densely packed structural oxygens and hydroxyl groups on the mineral surfaces.

Kalinichev, A. G.; Xu, X.; Kirkpatrick, R.

2006-12-01

74

NUMERICAL SIMULATION ON SEASONAL VARIATION IN DISSOLVED OXYGEN TENSION IN LAKE BIWA  

Microsoft Academic Search

A three-dimensional ecosystem model is developed for analysis of seasonal variation in dissolved oxygen tension in Lake Biwa. The ecosystem model consists of physical and chemical-biological submodels. The physical submodel is the hydrodynamic model driven directly by observed net surface heat flux. The chemical-biological submodel is a eutrophic level food web model, which includes phytoplankton, zooplankton, particulate and dissolved organic

Daisuke Kitazawa; Michio Kumagai

75

Determination of activated sludge biological activity using model corrected CO2 off-gas data.  

PubMed

Carbon dioxide (CO(2)) online off-gas monitoring is useful to detect changes in biological activity for activated sludge systems especially under limited oxygen conditions like under simultaneous nitrification-denitrification (SND) where respirometric measurements are not applicable. So far, the influence of the bicarbonate system on the liquid-gas transfer of CO(2) prevented the wider use of off-gas CO(2) for monitoring purposes in wastewater treatment. The objective of the paper is to demonstrate a practical method to correct measured off-gas CO(2) as an indicator of biological activity by taking into account pH shifts (resulting in CO(2) release or retention) and changes in influent alkalinity. The simple model is based on the physicochemical system of the bicarbonate/CO(2) equilibrium and the liquid-gas mass transfer for aerated systems. Standard on-line measurements (pH, temperature, flow rates) and periodical alkalinity titration serve as input data to estimate the influence of the carbonate system on the CO(2) off-gas concentrations measured on-line. For a particular plant the CO(2) mass transfer coefficients are derived from measurements compared to the theoretical calculation from oxygen mass transfer. The model estimates the biological carbon dioxide production rate (CPR; heterotrophic activity) by the correction of the measured carbon dioxide transfer rate (CTR; C-flux by the off-gas) with the calculated inorganic carbon dioxide transfer rate (r(F)) considering bicarbonate consumption (autotrophic activity). PMID:17292940

Weissenbacher, Norbert; Lenz, Katharina; Mahnik, Susanne N; Wett, Bernhard; Fuerhacker, Maria

2007-04-01

76

A novel isotopic fractionation during dissolved oxygen consumption in mesopelagic waters inferred from observation and model simulation of dissolved oxygen ?18O in open oceanic regions  

NASA Astrophysics Data System (ADS)

Oxygen isotopic ratio (?18O) of dissolved oxygen is a useful for bioactive tracer of the subsurface aphotic (mesopelagic) ocean since it varies nonlinearly related to oxygen consumption via stoichiometry of organic matter decomposition. Therefore, along with global circulation model (GCM), observed ?18O and their vertical/geographical distribution can be effectively used to quantitatively determine how marine biological and ocean physical processes contribute to varying dissolved oxygen (DO) concentration in the ocean, in particular mesopelagic zone where pronounced biological activity alters DO concentration significantly. In the central north Pacific Ocean and Indian Ocean, including Arabian Sea, one of the few regions in the open ocean which has oxygen minimum zone (OMZ, a layer with severely depleted DO), vertical profiles of DO and ?18O were observed. These observed data are compared with a GCM simulation in which a constant isotopic fractionation factor of DO by marine biological respiration and a fixed Redfield molar ratio between P and O are assumed. Even in the Arabian Sea OMZ, relationship between DO and ?18O was found to be similar to those observed in other open oceans, indicating that no specific oxygen consumption process occurred in the OMZ. Using the GCM model, we attempted to reproduce the observed overall relationship between DO and ?18O, but it failed when we adopted the previously reported isotopic fractionation factor: Discrepancy became larger when oxygen saturation level decreased, in particular in thermocline water (at 20% oxygen saturation level, modeled ?18O was heavier than observed values by +7‰). Sensitivity simulations with the GCM model revealed that (1) simply changing the intensity of oxygen consumption by respiration/organic matter decomposition nor physical processes (diffusion and/or advection) could explain the observed relationship between DO and ?18O, (2) applying a smaller isotopic fractionation for deep waters, rather than commonly used value obtained through laboratory studies for whole organism (0.98, Kiddon et al., 1993), could reproduce the observed relationship. Current result strongly suggests the unidentified deep metabolism process, such as complete oxygen consumption in sinking particles, is occurring in the mesopelagic waters.

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

2012-12-01

77

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

SciTech Connect

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

Herrmann, F.J.; Herrmann, B.; Hoeflich, V. [Wiederaufarbeitungsanlage Karlsruhe (Germany)] [and others

1997-08-01

78

Impact Of Melter Internal Design On Off-Gas Flammability  

SciTech Connect

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.

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

2012-05-30

79

Defining Dissolving  

NSDL National Science Digital Library

In this introductory activity, learners discover that sugar and food coloring dissolve in water but neither dissolves in oil. Based on their observations, learners can conclude that both solids and liquids can dissolve, but they don't necessarily dissolve in all liquids. Through this activity, learners will refine their definition of dissolve.

Kessler, James H.; Galvan, Patricia M.

2007-01-01

80

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

SciTech Connect

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.

Wright, G.T.

2001-08-16

81

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

USGS Publications Warehouse

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

Green, W. Reed

2013-01-01

82

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

USGS Publications Warehouse

In May 1996, the U.S. Geological Survey entered into a cooperative agreement with the Kershaw County Water and Sewer Authority to characterize and simulate the water quality in the Wateree River, South Carolina. Longitudinal profiling of dissolved-oxygen concentrations during the spring and summer of 1996 revealed dissolved-oxygen minimums occurring upstream from the point-source discharges. The mean dissolved-oxygen decrease upstream from the effluent discharges was 2.0 milligrams per liter, and the decrease downstream from the effluent discharges was 0.2 milligram per liter. Several theories were investigated to obtain an improved understanding of the dissolved-oxygen dynamics in the upper Wateree River. Data suggest that the dissolved-oxygen concentration decrease is associated with elevated levels of oxygen-consuming nutrients and metals that are flowing into the Wateree River from Lake Wateree. Analysis of long-term streamflow and water-quality data collected at two U.S. Geological Survey gaging stations suggests that no strong correlation exists between streamflow and dissolved-oxygen concentrations in the Wateree River. However, a strong negative correlation does exist between dissolved-oxygen concentrations and water temperature. Analysis of data from six South Carolina Department of Health and Environmental Control monitoring stations for 1980.95 revealed decreasing trends in ammonia nitrogen at all stations where data were available and decreasing trends in 5-day biochemical oxygen demand at three river stations. The influence of various hydrologic and point-source loading conditions on dissolved-oxygen concentrations in the Wateree River were determined by using results from water-quality simulations by the Branched Lagrangian Transport Model. The effects of five tributaries and four point-source discharges were included in the model. Data collected during two synoptic water-quality samplings on June 23.25 and August 11.13, 1997, were used to calibrate and validate the Branched Lagrangian Transport Model. The data include dye-tracer concentrations collected at six locations, stream-reaeration data collected at four locations, and water-quality and water-temperature data collected at nine locations. Hydraulic data for the Branched Lagrangian Transport Model were simulated by using the U.S. Geological Survey BRANCH one-dimensional, unsteady-flow model. Data that were used to calibrate and validate the BRANCH model included time-series of water-level and streamflow data at three locations. The domain of the hydraulic model and the transport model was a 57.3- and 43.5-mile reach of the river, respectively. A sensitivity analysis of the simulated dissolved-oxygen concentrations to model coefficients and data inputs indicated that the simulated dissolved-oxygen concentrations were most sensitive to changes in the boundary concentration inputs of water temperature and dissolved oxygen followed by sensitivity to the change in streamflow. A 35-percent increase in streamflow resulted in a negative normalized sensitivity index, indicating a decrease in dissolved-oxygen concentrations. The simulated dissolved-oxygen concentrations showed no significant sensitivity to changes in model input rate kinetics. To demonstrate the utility of the Branched Lagrangian Transport Model of the Wateree River, the model was used to simulate several hydrologic and water-quality scenarios to evaluate the effects on simulated dissolved-oxygen concentrations. The first scenario compared the 24-hour mean dissolved-oxygen concentrations for August 13, 1997, as simulated during the model validation, with simulations using two different streamflow patterns. The mean streamflow for August 13, 1997, was 2,000 cubic feet per second. Simulations were run using mean streamflows of 1,000 and 1,400 cubic feet per second while keeping the water-quality boundary conditions the same as were used during the validation simulations. When compared t

Feaster, Toby D.; Conrads, Paul A.

2000-01-01

83

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

SciTech Connect

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

Vance, R.F.

1991-12-01

84

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

SciTech Connect

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.

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

85

Development and validation of a combustion model for a fuel cell off-gas burner  

E-print Network

and environmentally clean power generation has never been so important. The increasing cost of fossil fuels and more stringent regulations on emissions (particularly CO2 and NOx), together with increasing demand for electricity, make the provision of cost... Development and Validation of a Combustion Model for a Fuel Cell Off-Gas Burner W. Tristan Collins Magdalene College University of Cambridge A dissertation submitted to the University of Cambridge for the degree of Doctor of Philosophy June 2008...

Collins, William Tristan

2008-10-14

86

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

NASA Astrophysics Data System (ADS)

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

Hofmann, A.

2004-03-01

87

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

SciTech Connect

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

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

2001-09-01

88

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

SciTech Connect

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

Fellinger, T

2005-04-08

89

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

SciTech Connect

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

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

2008-07-01

90

Simulating streamflow and dissolved organic matter export from a forested watershed  

NASA Astrophysics Data System (ADS)

Stream water concentrations of dissolved organic matter (DOM) exhibit large temporal variations during precipitation on forested, headwater catchments. We present a modeling framework appropriate for describing streamflow and event-driven export of DOM from small, forested watersheds. Our model links parametrically simple formulations for rainfall-runoff generation and soil water carbon dynamics. The rainfall-runoff formulation is developed by modifying the catchment model of Kirchner (2009) to account for hysteresis in the relationship between stream discharge and catchment water storage. Time series computations of catchment water storage are used by the soil carbon model to approximate the effects of leaching, adsorption, and mineralization on soil water DOM concentrations and the export of DOM from the terrestrial reservoir to the stream. Our findings show that this model is capable of reproducing hourly variations of stream discharge (ranging from 0.01 to 0.38 mm h-1) and stream water DOM concentrations (ranging from 1.8 to 14 mg C L-1) measured in a forested headwater stream in north central Massachusetts. Our analysis highlights the strong linkage between soil carbon dynamics and hydrological processes that govern catchment water storage and flow paths connecting the terrestrial system to the stream.

Xu, Na; Saiers, James E.; Wilson, Henry F.; Raymond, Peter A.

2012-05-01

91

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

SciTech Connect

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.

Lee, L.

1992-02-25

92

Simulation of water temperature and dissolved oxygen distribution in Lake Vegoritis, Greece  

Microsoft Academic Search

Changes in lake water temperature and temperature stratification dynamics can have a profound effect on lake biological and chemical processes. A one-dimensional temperature stratification and oxygen prediction model was developed to simulate the seasonal temperature cycle and oxygen distribution for Lake Vegoritis in Northern Greece. The submodel of heat transport is based on the non-linear heat transfer equation using daily

Vassilis Z Antonopoulos; Soultana K Gianniou

2003-01-01

93

LIMNOLOGICAL MODELLING: SIMULATION OF VERTICAL PROFILES OF TEMPERATURE, DISSOLVED OXYGEN AND NUTRIENTS. I. THEORY  

Microsoft Academic Search

In a body of water, variations occur in all limnological parameters on many time and space scales. Modelling can either be specific - for a selected subset; or can attempt to simulate the gross characteristics of e.g. current, temperature, algal blooms over an annual cycle (or longer). Vertical profiles perhaps give the greatest information for assessment of water quality. For

B. Henderson-Sellers

1980-01-01

94

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

SciTech Connect

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

Goddard, William

2012-11-30

95

Clean combustion off-gas. Final report. Southeastern Regional Biomass Energy Program  

SciTech Connect

A bench scale working model of a patented rotary recycling separator for pyrolysis off-gases has been fabricated and tested. The device has been heated to collect only high boiling organics and refrigerated to collect more than 98 percent of the water and organics in test off-gas streams. The performance was improved by changing the shape of the outer shell and by adjusting the headspace above the self cleaning internal rotor. The cost of construction and the operating energy required are estimated to be similar to those of the condensers and cyclones in common use. 14 refs., 9 figs., 2 tabs.

Elston, L.W.; Redkevitch, Z.; Knight, J.A.

1985-07-01

96

Simulated long-term temperature and dissolved oxygen characteristics of lakes in the north-central United States and associated fish habitat limits  

Microsoft Academic Search

Water temperatures and dissolved oxygen (DO) concentrations in lakes are related to climate. Temperature and DO in 27 lake classes (3 depth classes x 3 surface area classes x 3 trophic states) were simulated by numerical models with daily weather data input. The weather data used are from the 25-yr period 1955- 1979. The lakes and the weather are representative

H. G. Stefan; J. G. Eaton; J. H. McCormick

1996-01-01

97

Approximate solution to simulate dissolved contaminant transport in groundwater from prism source  

NASA Astrophysics Data System (ADS)

SummaryMost analytical solutions for contaminant transport in groundwater require numerical integration, which can be difficult to apply in spreadsheets. The Domenico solution provides an approximate solution without the integral term for a planar source oriented normal to the direction of groundwater flow. In this paper, the Domenico solution is extended to a prism source by considering off-domain contaminant transport. The source was lengthened by using the ratio between longitudinal and horizontal transverse hydrodynamic dispersion coefficients and source thickness by using the ratio between vertical velocity of source loading and longitudinal velocity of contaminant transport. The modified Domenico solution was tested against previous exact solutions. Results show that the modified Domenico solution simulates higher contaminant concentrations near the source and in the bottom of the domain than the Domenico solution but yields similar plumes to the exact solutions. The modified Domenico solution provides quick estimation of the plume length and concentrations and is convenient for testing the response of plume length and concentrations to measurable input parameters when a three-dimensional representation of the source is important.

Promma, Kitchakarn

2010-08-01

98

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

SciTech Connect

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

John Twining; Peter McGlinn; Elaine Loi; Kath Smith; Reto Giere [Australian Nuclear Science and Technology Organisation, Menai, NSW (Australia)

2005-10-01

99

Selection among aqueous and off-gas treatment technologies for synthetic organic chemicals  

SciTech Connect

A methodology for selecting the least-cost treatment technology for waters contaminated by organic wastes was developed using performance and cost models. This methodology simplifies the selection of the least expensive treatment process(es) for a given set of conditions. Two aqueous-phase treatment options were considered: air stripping and liquid-phase adsorption (granular activated carbon). When the off-gases from air stripping must be treated, four off-gas treatment options were considered: gas-phase adsorption (with both on- and off-site regeneration of the granular activated carbon), thermal incineration, and catalytic oxidation. Methodologies were developed for rapidly selecting the least-cost off-gas treatment option [for volatile organic compound (VOC) sources such as an air stripping tower], for selecting the least-cost overall (liquid and gas phase treatment) system, and for selecting the least-cost overall system for a multicomponent mixture. The comparison methodology is based on physical parameters of the target chemical: Henry`s constant and the solute distribution parameter. The results are a set of diagrams and heuristics for rapid identification of cases for which one treatment option is significantly less expensive than the other.

Dvorak, B.I. [Univ. of Nebraska, Lincoln, NE (United States). Dept. of Civil Engineering; Herbeck, C.J. [County Sanitation District of Los Angeles County, Whittier, CA (United States); Meurer, C.P. [Bee County Coll., Beeville, TX (United States); Lawler, D.F.; Speitel, G.E. Jr. [Univ. of Texas, Austin, TX (United States). Dept. of Civil Engineering

1996-07-01

100

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

SciTech Connect

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).

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

101

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

SciTech Connect

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

MAY TH

2008-04-16

102

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

NASA Astrophysics Data System (ADS)

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.

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

2014-11-01

103

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

SciTech Connect

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.

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

1983-09-01

104

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

SciTech Connect

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

Zamecnik, J.; Choi, A.

2009-03-25

105

Single and two-phase numerical models of Dissolved Air Flotation: Comparison of 2D and 3D simulations  

Microsoft Academic Search

In this work single- and two-phase flow numerical models of a pilot DAF (Dissolved Air Flotation) tank are presented. In the latter framework, the mixture in the tank consists of water and air bubbles. The motion of air bubbles is resolved within the Lagrangian frame of reference. Interaction between bubbles is neglected in the present model. To account for turbulence

Mia Bondelind; Srdjan Sasic; Margaritis Kostoglou; Lars Bergdahl; Thomas J. R. Pettersson

2010-01-01

106

Release model for in situ vitrification large-field test off-gas treatment system  

SciTech Connect

A conceptual model for the vapor and aerosol transport and deposition in the in situ vitrification large-field test off-gas system (OGS) has been developed. This model can be used to predict the emissions from the OGS under normal and off-normal conditions. Results generated by the model can be used to evaluate design and/or procedural modifications, define tests, and predict results. The OGS vapor and aerosol transport and deposition is modeled using the PULSE/MOD-ISV/VER 1.0.0 developmental computer code. Input data requirements for this code include the specific geometries of the OGS components; the composition, rate, and temperature of the vapors and aerosols entering the OGS; and the OGS component surface temperatures or heat fluxes. Currently, not all of these model inputs are available. Therefore, conceptual input parameters are developed. Using this input data, preliminary calculations with the code have been performed. These calculations include a demonstration that the code predicts convergent results, a comparison of predicted results with performance data for one of the OGS components, and a preliminary sensitivity study of the complete model.

Pafford, D.J.; Tung, V.X.

1992-03-01

107

Parametric studies of off-gas release during in situ vitrification  

SciTech Connect

Off-gases are released from underground sources during the In Situ Vitrification (ISV) process. Most of these gases will be generated beyond the melt front where advancing high temperatures will cause pyrolysis and vaporization of organic and volatile materials. Some of these gases will enter the bottom of the melt pool and propagate upwards to the surface where they will enter the ISV confinement hood. A computer code called OGRE (Off-Gas RElease) has been written to model bubble-rise physics in the melt pool for given volumetric gas flux rates into the bottom of the pool. The models incorporated into OGRE have previously been reported. The purpose of the present document is to report the results of a series of parametric studies performed with OGRE. The numerical studies involve the variation of seventeen parameters for each of the two different inlet bubble-size models. Results indicate that while predictions appear qualitatively reasonable, additional development of the agglomeration and drift flux models is needed. This development will require experimental data for bubble formation and terminal velocity. 5 refs., 36 figs., 2 tabs.

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

1990-09-01

108

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

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)

Burns, A.W.

1989-01-01

109

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

SciTech Connect

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.

Nick Soelberg; Joe Enneking

2011-05-01

110

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

SciTech Connect

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

Zamecnik, J.; Choi, A.

2010-08-18

111

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

SciTech Connect

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

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

1990-07-01

112

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

NASA Astrophysics Data System (ADS)

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

Aktinol, Eduardo

113

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

SciTech Connect

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.

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

114

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

PubMed

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

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

2013-01-01

115

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

SciTech Connect

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.

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

1996-03-01

116

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

SciTech Connect

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.

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

2012-10-30

117

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

USGS Publications Warehouse

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.

Jobson, Harvey E.

1985-01-01

118

Wormhole formation in dissolving fractures  

Microsoft Academic Search

We investigate the dissolution of artificial fractures with three-dimensional, pore-scale numerical simulations. The fluid velocity in the fracture space was determined from a lattice Boltzmann method, and a stochastic solver was used for the transport of dissolved species. Numerical simulations were used to study conditions under which long conduits (wormholes) form in an initially rough but spatially homogeneous fracture. The

P. Szymczak; A. J. C. Ladd

2009-01-01

119

Dissolved Oxygen and Temperature  

Microsoft Academic Search

Dissolved oxygen and temperature are two of the fundamental variables in lake and pond ecology. By measuring dissolved oxygen and temperature, scientists can gauge the overall condition of waterbodies. Aquatic organisms need dissolved oxygen for their survival. While water temperature also directly influences aquatic organ- isms, it regulates dissolved oxygen concentrations within a lake. Dissolved oxygen and temperature are also

Kelly Addy; Linda Green

120

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

SciTech Connect

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.

TERRI, FELLINGER

2004-12-21

121

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

122

Comparing the behaviour of two ocean surface models in simulating dissolved O 2 concentration at O.W.S.P.  

NASA Astrophysics Data System (ADS)

We compare the simulation of the O 2 concentration in the mixed layer at Sta. P using two different mixed layer models with the same biological production-consumption function. One is the integral mixed layer model already used by THOMASet al. (Deep-Sea Research, 37, 463-491, 1990). The other is the eddy kinetic energy (EKE) model of GASPARet al. (Journal of Geophysical Research, 95, 16179-16194, 1990). The latter simulates better both the seasonal and the short time evolution of the oxygen concentration. The submixed layer summer supersaturation is also closer to observations, by about 25%, though a factor of 2 too high: this could be improved by adjustment of the production function. The net annual gas exchange flux with the atmosphere is always a degassing of the order of 10% of the total biological production. In general, the model values are smaller (within a factor of 3 for the EKE model) than the data. However, the latter may not be robust as 96 measurements per year are necessary to estimate this flux within a factor of 10.

Thomas, F.; Minster, J. F.; Gaspar, P.; Gregoris, Y.

1993-02-01

123

Dissolved Oxygen Protocol  

NSDL National Science Digital Library

The purpose of this resource is to measure the amount of oxygen dissolved in water. Students use a dissolved oxygen kit or meter to measure the dissolved oxygen in the water at their hydrology site. The exact procedure depends on the instructions in the dissolved oxygen kit or meter used. The meter requires calibration before use.

The GLOBE Program, UCAR (University Corporation for Atmospheric Research)

2003-08-01

124

Chemistry Review: Dissolving  

NSDL National Science Digital Library

This resource clearly defines and summarizes all the aspects of the dissolving of liquids, with detailed examples of different substances dissolving together. There are videos that show dissolving examples, as well as models that show substances at their molecular level. The chemical make-up of substances such as water and oil are included to better understand the dissolving process and to learn which substances dissolve and which ones do not.

Kessler, James; Galvan, Patti

2010-01-01

125

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

NASA Astrophysics Data System (ADS)

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.

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

2013-10-01

126

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

Impact of circulation on export production, dissolved organic matter, and dissolved oxygen) and dissolved oxygen simulated by 12 global ocean models participating in the second phase of the Ocean Carbon matter, and dissolved oxygen in the ocean: Results from Phase II of the Ocean Carbon-cycle Model

Follows, Mick

127

Photobleaching of humic rich dissolved organic matter  

Microsoft Academic Search

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

Thomas Brinkmann; Daniel Sartorius; Fritz H. Frimmel

2003-01-01

128

Pill Dissolving Demo  

NSDL National Science Digital Library

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.

Vu Bioengineering Ret Program

129

Dissolved Oxygen Activity  

NSDL National Science Digital Library

One of the most important measures of the health of the stream is the level of dissolved oxygen (DO) in the water. Oxygen (O2) dissolves in water through the mixing of the water surface with the atmosphere. The oxygen is used by fish and other animals in the water to "breath" through their gills or other respiratory systems and by plants. If the levels fall too low, many species of fish, macroinvertebrates, and plants cannot survive. At very low levels of oxygen, the stream becomes "septic" and smells rotten because low oxygen sulfur bacteria begin to dominate.

Gordon, Steve

130

Dissolved Oxygen Model  

NSDL National Science Digital Library

One of the most important measures of the health of the stream is the level of dissolved oxygen (DO) in the water. Oxygen (O2) dissolves in water through the mixing of the water surface with the atmosphere. The oxygen is used by fish and other animals in the water to "breath" through their gills or other respiratory systems and by plants. If the levels fall too low, many species of fish, macroinvertebrates, and plants cannot survive. At very low levels of oxygen, the stream becomes "septic" and smells rotten because low oxygen sulfur bacteria begin to dominate.

Gordon, Steve

131

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

USGS Publications Warehouse

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

Russo, Thomas N.; McQuivey, Raul S.

1975-01-01

132

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

PubMed

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

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

2014-01-23

133

ADDING REALISM TO NUCLEAR MATERIAL DISSOLVING ANALYSIS  

SciTech Connect

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.

Williamson, B.

2011-08-15

134

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

SciTech Connect

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

Chudnovsky, Yaroslav; Kozlov, Aleksandr

2013-08-15

135

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

SciTech Connect

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

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

2011-12-29

136

Off gas film cooler cleaner  

DOEpatents

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

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

1997-08-26

137

How to Measure Dissolved Oxygen  

NSDL National Science Digital Library

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.

Ecology, Washington S.

138

Dissolving Different Liquids in Water  

NSDL National Science Digital Library

In this activity, learners add different liquids to water and apply their working definition of âdissolvingâ to their observations. After observing isopropyl rubbing alcohol, vegetable oil, and corn syrup in water, learners can conclude that while some liquids may dissolve in water, different liquids dissolve in water to different extents. Adult supervision recommended.

Kessler, James H.; Galvan, Patricia M.

2007-01-01

139

Middle School Chemistry: The Water Molecule and Dissolving  

NSDL National Science Digital Library

This set of multimedia lessons, developed by the American Chemical Society, examines the process of dissolving materials in water. Videos, interactive simulations, hands-on labs, and demonstrations are all integrated into a 9-part unit of instruction that includes assessments and background information. Students will explore why water dissolves salt and sugar, conduct solubility tests, investigate how temperature affects dissolving, and more. Editor's Note: The authors designed this curriculum to help students understand basic chemistry within a framework of molecular interactions. The molecular models and related animations provide a foundation for understanding states of matter, atomic models and bonding, charge interactions, and chemical change.

Galvan, Patti; Kessler, Jim

2011-06-27

140

Effects of dissolved oxygen on passive behavior of stainless alloys  

Microsoft Academic Search

A potential-control circuit has been devised to measure passive-current (corrosion rate) on stainless alloys in conditions simulating the usual noble drift of the open-circuit corrosion potential in the presence of passivating dissolved oxidizers. Open-circuit corrosion potential and passive-current decay were measured with and without dissolved oxygen in dilute sulfuric acid solutions as a function of time on austenitic stainless steel

K. S. Raja; D. A. Jones

2006-01-01

141

Fast dissolving films: a review.  

PubMed

Fast-dissolving drug delivery systems have been developed as an alternative to conventional dosage form as an oral means of drug delivery in case of chronic conditions. Now a day's fast dissolving films are preferred over conventional tablets and capsules for masking the taste of bitter drugs to increase the patient compliance. Fast dissolving films consist of a very thin oral strip which dissolves in less than one minute when placed on the tongue. Dissolvable oral thin films are in the market since past few years in the form of breath strips and are widely accepted by consumers for delivering vitamins, vaccines and other drug products. The various manufacturing techniques for the preparation of films have also been detailed in the review. The present review details most of the patents on such fast dissolving films in recent years. A brief study has been made on various parameters which are used to evaluate such films. In case of chronic disorders these fast dissolving films are better for delivering drugs and obtaining faster therapeutic blood levels and superior in comparison to other oral conventional dosage forms. PMID:21453260

Chaturvedi, Ankita; Srivastava, Pranati; Yadav, Sunita; Bansal, Mayank; Garg, Garima; Sharma, Pramod Kumar

2011-07-01

142

The Measurement of Dissolved Oxygen  

ERIC Educational Resources Information Center

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

Thistlethwayte, D.; And Others

1974-01-01

143

Clarification of LWR Dissolver Solutions.  

National Technical Information Service (NTIS)

When high-burnup LWR fuels are reprocessed, fission products cause solids formation during solvent extraction. Several methods for clarifying LWR dissolver solutions have been evaluated. Chemical treatment as well as centrifugation will be necessary to pr...

M. J. Plodinec

1978-01-01

144

Behavior of mercury and iodine during vitrification of simulated alkaline Purex waste  

SciTech Connect

Current plans indicate that the high-level wastes stored at the Savannah River Plant will be solidified by vitrification. The behavior of mercury and iodine during the vitrification process is of concern because: mercury is present in the waste in high concentrations (0.1 to 2.8 wt%); mercury will react with iodine and the other halogens present in the waste during vitrification and; the mercury compounds formed will be volatilized from the vitrification process placing a high particulate load in the vitrification system off-gas. Twelve experiments were completed to study the behavior of mercury during vitrification of simulated SRP Purex waste. The mercury was completely volatized from the vitrification system in all experiments. The mercury reacted with iodine, chlorine and oxygen to form a fine particulate solid. Quantitative recovery of mercury compounds formed in the vitrification system off-gas was not possible due to high (37 to 90%) deposition of solids in the off-gas piping. The behavior of mercury and iodine was most strongly influenced by the vitrification system atmosphere. During experiments performed in which the oxygen content of the vitrification system atmosphere was low (< 1 vol%); iodine retention in the glass product was 27 to 55%, the mercury composition of the solids recovered from the off-gas scrub solutions was 75 to 85 wt%, and a small quantity of metallic mercury was recovered from the off-gas scrub solution. During experiments performed in which the oxygen content of the vitrification system atmosphere was high (20 vol%), iodide retention in the glass product was 3 to 15%, the mercury composition of the solids recovered from the off-gas scrub solutions was 60 to 80 wt%, and very little metallic mercury was recovered from the off-gas scrub solution.

Holton, L.K.

1981-09-01

145

Reducing emissions from uranium dissolving  

SciTech Connect

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.

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

1992-10-01

146

Reducing emissions from uranium dissolving  

SciTech Connect

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.

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

1992-10-01

147

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

NSDL National Science Digital Library

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.

Charlie Hunter (Southwestern College;); Sarah Kenick (University of New Hampshire;); Brian White (University of Massachusettes ;); ;

2006-06-18

148

Dissolving a Substance in Different Liquids  

NSDL National Science Digital Library

In this activity, learners make colored sugar and add it to water, alcohol, and oil to discover some interesting differences in dissolving. The sugar will dissolve to a different extent in each liquid, and the color may or may not dissolve depending on the liquid. Learners also have an opportunity to refine their definition of the term dissolve. Adult supervision recommended.

Kessler, James H.; Galvan, Patricia M.

2007-01-01

149

Dissolved organic matter (DOM) in recycled leachate of bioreactor landfill  

Microsoft Academic Search

Landfill leachate needs sufficient treatment before safe disposal. Bioreactor landfill technology could effectively degrade the organic matters in recirculated leachate, hence leaving a leachate stream of low biodegradability. This study characterized the dissolved organic matter (DOM) in the leachate from simulated bioreactor landfill columns with or without presence of trace oxygen. The removal efficiencies of this DOM using coagulation–sedimentation or

Pin-jing He; Jun-feng Xue; Li-ming Shao; Guo-jian Li; Duu-Jong Lee

2006-01-01

150

Group of Microbes Change Dissolved  

E-print Network

't likely to be cost-effective. Photography by Araldo de Luca/CORBIS Ten years ago Derek Lovley their energy by breathing in dissolved forms of toxic metals, such as uranium and cadmium, and converting them sense, he said. "You couldn't use this process to harvest the gold from the ocean. The cost in pumping

Lovley, Derek

151

Dissolved oxygen and fish behavior  

Microsoft Academic Search

Synopsis This essay reviews the behavioral responses of fish to reduced levels of dissolved oxygen from the perspective of optimization theory as used in contemporary behavioral ecology. A consideration of oxygen as a resource suggests that net oxygen gain per unit of energy expenditure will be the most useful currency for ecological models of breathing. In the process of oxygen

Donald L. Kramer

1987-01-01

152

Phase fluorometric dissolved oxygen sensor  

Microsoft Academic Search

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

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

2001-01-01

153

DISSOLVED OXYGEN DIURNAL FLUX STUDY  

EPA Science Inventory

Stream monitoring study of a 24 Western Corn Belt Plains streams designed to assess any correlation of nutrient loads and the level of dissolved oxygen in wadeable streams and any subsequent affect on aquatic life. Study currently being conducted under a cooperative agreement be...

154

Nonlinear Constrained Predictive Control of dissolved oxygen in bio-reactor  

Microsoft Academic Search

A nonlinear constrained model predictive control (NCMPC) method is presented for the control of the dissolved oxygen in a bio-reactor system using Hammerstein model. The control of dissolved oxygen as output is accomplished by adjusting the stirrer speed as input. The proposed controller is compared with the Nonlinear Model Predictive Control(NMPC) method without input constraints. The simulations and experiments are

Xu Zhe; Shouqi Cao; Hak Kyeong Kim; Sang Bong Kim

2008-01-01

155

Dissolved Oxygen and Biochemical Oxygen Demand  

NSDL National Science Digital Library

This EPA website provides general information about dissolved oxygen, including what it is, sampling and equipment considerations, and sampling and analysis protocols. The site also features a chart of dissolved oxygen solubility as a function of temperature.

Agency, U. S.

156

Dissolved Oxygen and Biochemical Oxygen Demand  

NSDL National Science Digital Library

This Environmental Protection Agency (EPA) website provides general information about dissolved oxygen, including what it is, sampling and equipment considerations, and sampling and analysis protocols. The site also features a chart of dissolved oxygen solubility as a function of temperature.

2010-03-02

157

Water quality modeling of the effects of macrophytes on dissolved oxygen in a shallow tailwater reservoir  

Microsoft Academic Search

Lake Ogallala, a 260-hectare tailwater reservoir, is subject to wide fluctuations of inflow water quality and quantity. These fluctuations impact lake temperatures, water stage, dissolved oxygen (DO), and nutrients. A two-dimensional, continuous simulation hydrodynamic and water quality model, CE-QUAL-W2, was used to simulate dissolved oxygen levels and to quantify DO sources and sinks in the lake. The elements modeled include

J. Stansbury; L. Kozimor; D. Admiraal; E. Dove

2008-01-01

158

A vertical distribution model of nutrients and dissolved oxygen in the southern Taiwan Strait  

Microsoft Academic Search

Since vertical transport of nutrients and dissolved oxygen are quite important in the water column and have drawn serious\\u000a attention these recent years, a one-dimension numerical model is tried to simulate the vertical distribution of nutrients\\u000a and dissolved oxygen in June at two research sites in the southern Taiwan Strait. Physical transport parameters are calibrated\\u000a by temperature simulation, and them

Shang Shao-Ling; Hong Hua-Sheng

1995-01-01

159

Secret Agents of Dissolved Oxygen  

NSDL National Science Digital Library

This activity explores how water chemistry is altered by the biological processes of phytoplankton (microscopic photosynthetic organisms). Students will discover what some of these water chemistry changes are, and what influences these changes (type of water, exposure to light, etc.). The students will design an activity based on experience gained from the first activity. They will determine the changes and causes thereof in different types of water in a sealed container over time, and learn to measure dissolved oxygen, temperature, and carbon dioxide with a calculator/computer probe-ware or by other means.

Dawson, Besse

160

Recalcitrant dissolved organic carbon fractions.  

PubMed

Marine dissolved organic carbon (DOC) exhibits a spectrum of reactivity, from very fast turnover of the most bioavailable forms in the surface ocean to long-lived materials circulating within the ocean abyss. These disparate reactivities group DOC by fractions with distinctive functions in the cycling of carbon, ranging from support of the microbial loop to involvement in the biological pump to a hypothesized major source/sink of atmospheric CO(2) driving paleoclimate variability. Here, the major fractions constituting the global ocean's recalcitrant DOC pool are quantitatively and qualitatively characterized with reference to their roles in carbon biogeochemistry. A nomenclature for the fractions is proposed based on those roles. PMID:22881353

Hansell, Dennis A

2013-01-01

161

Photochemical and microbial consumption of dissolved organic carbon and dissolved oxygen in the Amazon River system  

Microsoft Academic Search

Bacterial and photochemical mineralization of dissolved organic matter were investigated in the Amazon River system. Dissolved oxygen, dissolved organic carbon (DOC), and bacterial growth were measured during incubations conducted under natural sunlight and in the dark. Substrate addition experiments indicated that the relatively low rates of bacterial activity in Amazon River water were caused by C limitation. Experiments to determine

R. M. W. Amon; R. Benner

1996-01-01

162

Impact of circulation on export production, dissolved organic matter, and dissolved oxygen in the ocean: Results from Phase II of the Ocean Carbon-cycle Model Intercomparison Project (OCMIP-2)  

Microsoft Academic Search

Results are presented of export production, dissolved organic matter (DOM) and dissolved oxygen simulated by 12 global ocean models participating in the second phase of the Ocean Carbon-cycle Model Intercomparison Project. A common, simple biogeochemical model is utilized in different coarse-resolution ocean circulation models. The model mean (±1?) downward flux of organic matter across 75 m depth is 17 ±

R. G. Najjar; X. Jin; F. Louanchi; O. Aumont; K. Caldeira; S. C. Doney; J.-C. Dutay; M. Follows; N. Gruber; F. Joos; K. Lindsay; E. Maier-Reimer; R. J. Matear; K. Matsumoto; P. Monfray; A. Mouchet; J. C. Orr; G.-K. Plattner; J. L. Sarmiento; R. Schlitzer; R. D. Slater; M.-F. Weirig; Y. Yamanaka; A. Yool

2007-01-01

163

Impact of circulation on export production, dissolved organic matter, and dissolved oxygen in the ocean: Results from Phase II of the Ocean Carbon-cycle Model Intercomparison Project (OCMIP-2)  

Microsoft Academic Search

Results are presented of export production, dissolved organic matter (DOM) and dissolved oxygen simulated by 12 global ocean models participating in the second phase of the Ocean Carbon-cycle Model Intercomparison Project. A common, simple biogeochemical model is utilized in different coarse-resolution ocean circulation models. The model mean (+\\/-1sigma) downward flux of organic matter across 75 m depth is 17 +\\/-

R. G. Najjar; X. Jin; F. Louanchi; O. Aumont; K. Caldeira; S. C. Doney; J.-C. Dutay; M. Follows; N. Gruber; F. Joos; K. Lindsay; E. Maier-Reimer; R. J. Matear; K. Matsumoto; P. Monfray; A. Mouchet; J. C. Orr; G.-K. Plattner; J. L. Sarmiento; R. Schlitzer; R. D. Slater; M.-F. Weirig; Y. Yamanaka; A. Yool

2007-01-01

164

Improved Technology for Dissolved Oxygen Measurement  

Microsoft Academic Search

The need for measurement and control of dissolved oxygen at very low concentrations in ultrapure water for some wafer processes has been recognized for many years. Dissolved oxygen instrumentation has been developed that increases the reliability and greatly reduces the maintenance requirements and costs of this specialized measurement. Combining the strengths of traditional diffusion membrane sensors with those of equilibrium-type

David M. Gray

165

Diffusion of dissolved oxygen through concrete  

Microsoft Academic Search

The rate of steel corrosion for concrete structures in the ocean is supposed to be controlled primarily by diffusion of dissolved oxygen through the concrete cover. Experiments were performed to study the diffusion rate of dissolved oxygen through submerged concrete of different qualities and thicknesses. Several test methods for studying the diffusion were developed, and from the test results it

O. E. Gjorv; O. Vennesland; A. H. S. El-Busaidy

1987-01-01

166

Dissolved gas analysis using expert system  

Microsoft Academic Search

This project is to study a dissolved gas analysis of transformer oil using an expert system. A prototype of an expert system based on the dissolved gas analysis techniques for diagnosis of a suspected transformer faults and the appropriate maintenance actions to be taken. This method is proposed to assist the conventional gas ratio method based on the International Electrotechnical

Maizun Binti Ahmad; Z. bin Yaacob

2002-01-01

167

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

NASA Technical Reports Server (NTRS)

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.

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

168

Effects of Dissolved Water Constituents on the Photodegradation of Fenitrothion and Diazinon  

Microsoft Academic Search

The photochemical degradation of two widely used organophosphorothioate insecticides, fenitrothion and diazinon, was investigated\\u000a in aqueous solutions containing three separate dissolved constituents commonly found in natural waters (NO3?, CO32? and dissolved organic matter (DOC)). The effect of these constituents on pesticide photodegradation was compared to degradation\\u000a in “constituent-free” pure water. Solutions were irradiated in an Atlas solar simulator fitted with

Justina E. Ukpebor; Crispin J. Halsall

169

Thermodynamic simulations of lignite-fired IGCC with in situ desulfurization and CO 2 capture  

Microsoft Academic Search

IGCC cycles running on Greek lignite with in situ desulfurization and CO2 capture were simulated using the ASPEN PLUS process simulator and compared with other power cycles. Dolomite was chosen as the material for in situ desulfurization. Considering the power produced and residual sulfur content of the off-gas, an oxygen-blown gasifier operated at 1.8 MPa and 950°C, having a thermal

Wim F. Elseviers; Tania Van Mierlo; Martine J. F. Van de Voorde; Harry Verelst

1996-01-01

170

Fuel Mystery Dis-Solved!  

NSDL National Science Digital Library

In this activity, students investigate the simulated use of solid rocket fuel by using an antacid tablet. Students observe the effect that surface area and temperature has on chemical reactions. Also, students compare the reaction time using two different reactants: water and vinegar. Finally, students report their results using a bar graph.

Integrated Teaching And Learning Program

171

Application and evaluation of scale dissolver treatments  

SciTech Connect

In order to provide an improved basis for the design of barium sulfate scale dissolver treatments both laboratory testing and monitoring of field applications were carried out. The deleterious effects of mixing produced water with dissolver prior to contacting scale are shown. Increasing total dissolved solids (TDS) levels can reduce dissolution depending upon temperature. Precomplexation with divalent cations reduces the capacity of the dissolver to solubilize solid scales. Magnesium may adversely affect dissolver performance at elevated temperatures. Several oil and gas wells were closely monitored during initial flowback after treatment. Samples were collected on a frequent basis and analyzed for pH, dissolver content, chlorides and various cations. The resulting data were used to construct flowback profiles for evaluation of the treatments. Evidence of scale dissolution is presented. The presence of an incompatible flush brine was discovered in one case and possible reverse order of addition of preflush and dissolver in another. The importance of establishing and following treatment procedures is briefly discussed.

Fielder, G.D. [Baker Performance Chemicals, Inc., Sand Springs, OK (United States)

1994-12-31

172

Dissolved Concentration Limits of Radioactive Elements.  

National Technical Information Service (NTIS)

The purpose of this study is to evaluate dissolved concentration limits (also referred to as solubility limits) of radioactive elements under possible repository conditions, based on geochemical modeling calculations using geochemical modeling tools, ther...

2005-01-01

173

27 CFR 19.455 - Dissolving of denaturants.  

Code of Federal Regulations, 2010 CFR

...Dissolving of denaturants. Denaturants which are difficult to dissolve in spirits at usual working temperatures, which are highly...be liquefied or dissolved in a small quantity of spirits or water in advance of their use in the production of...

2010-04-01

174

Progress in dissolving modified LEU Cintichem targets  

Microsoft Academic Search

A process is under development to use low-enriched uranium (LEU) metal targets for production of ⁹⁹Mo. The first step is to dissolve the irradiated foil. In past work, this has been done by heating a closed (sealed) vessel containing the foil and a solution of nitric and sulfuric acids. In this work, the authors have demonstrated that (1) the dissolver

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

1996-01-01

175

Dissolved Fe(II) in a river-estuary system rich in dissolved organic matter  

NASA Astrophysics Data System (ADS)

Reduced iron, Fe(II), accounts for a significant fraction of dissolved Fe across many natural surface waters despite its rapid oxidation under oxic conditions. Here we investigate the temporal and spatial variation in dissolved Fe redox state in a high dissolved organic matter (DOM) estuarine system, the River Beaulieu. We couple manual sample collection with the deployment of an autonomous in situ analyser, designed to simultaneously measure dissolved Fe(II) and total dissolved Fe, in order to investigate processes operating on the diurnal timescale and to evaluate the performance of the analyser in a high DOM environment. Concentrations of dissolved Fe available to the ligand ferrozine are elevated throughout the estuary (up to 21 ?M in freshwater) and notably higher than those previously reported likely due to seasonal variation. Fe(II) is observed to account for a large, varying fraction of the dissolved Fe available to ferrozine (25.5 ± 12.5%) and this fraction decreases with increasing salinity. We demonstrate that the very high DOM concentration in this environment and association of this DOM with dissolved Fe, prevents the accurate measurement of dissolved Fe concentrations in situ using a sensor reliant on rapid competitive ligand exchange.

Hopwood, Mark J.; Statham, Peter J.; Milani, Ambra

2014-12-01

176

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

USGS Publications Warehouse

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

Foster, Katharine; Kenney, Terry A.

2010-01-01

177

Suspended sediment, dissolved organic carbon, and dissolved nitrogen export during the dam removal process  

Microsoft Academic Search

(1) Total suspended solids (TSS), dissolved organic carbon (DOC), and total dissolved nitrogen (TDN) loads were calculated for all stages of the dam removal process (dewatering, breaching, and removal) at various points upstream, within, and downstream of Lowell Mill Impoundment on the Little River, North Carolina. The impoundment dewatering exported loads of TSS, DOC, and TDN which were all 1-2

J. Adam Riggsbee; Jason P. Julian; Martin W. Doyle; Robert G. Wetzel

2007-01-01

178

Method for dissolving hard-to-dissolve thorium and/or plutonium oxides  

SciTech Connect

Method for dissolving hard-to-dissolve thorium and/or plutonium oxides, especially dioxides such as ThO2, PuO2 or (U/Pu)O2 mixed oxides by heating the oxides in a hermetically sealed vessel in fluoride-free nitric acid. The use of a gas atmosphere containing oxygen in the sealed vessel is advantageous.

Ledebrink, F.-W.; Rosenkranz, W.; Stoll, W.

1985-07-09

179

IMPROVEMENTS IN MODELLING DISSOLVED OXYGEN IN ACTIVATED SLUDGE SYSTEMS  

E-print Network

1 IMPROVEMENTS IN MODELLING DISSOLVED OXYGEN IN ACTIVATED SLUDGE SYSTEMS Jacek Makinia*, Scott A and variations in the aeration intensity on changes in the predicted dissolved oxygen (DO) concentrations for dissolved oxygen. KEYWORDS Activated sludge; dispersion; dissolved oxygen dynamics; mass transfer

Wells, Scott A.

180

A review on mouth dissolving films.  

PubMed

The ultimate goal of any drug delivery system is the successful delivery of the drug to the body; however, patient compliance must not be overlooked. Fast dissolving drug delivery systems, such as, Mouth Dissolving Films (MDF), offer a convenient way of dosing medications, not only to special population groups with swallowing difficulties such as children and the elderly, but also to the general population. MDF are the novel dosage forms that disintegrate and dissolve within the oral cavity. Intra-oral absorption permits rapid onset of action and helps by-pass first-pass effects, thereby reducing the unit dose required to produce desired therapeutic effect. The present review provides an overview of various polymers that can be employed in the manufacture of MDF and highlights the effect of polymers and plasticizers on various physico-mechanical properties of MDF. It further gives a brief account of formulation of MDF and problems faced during its manufacture. PMID:19751197

Dahiya, Meenu; Saha, Sumit; Shahiwala, Aliasgar F

2009-10-01

181

A Quantitative Evaluation of Dissolved Oxygen Instrumentation  

NASA Technical Reports Server (NTRS)

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

Pijanowski, Barbara S.

1971-01-01

182

Process for coal liquefaction in staged dissolvers  

DOEpatents

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.

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

1983-01-01

183

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

SciTech Connect

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.

Olguin, L.J.

1980-03-01

184

Industrial experience with dissolved-air flotation  

Microsoft Academic Search

Operating and analytical data relating to the application of dissolved-air flotation to the treatment of industrial wastewaters from various sources are presented including typical values for influent flow rate, rate of recycle, air-solid ratio, and hydraulic loading for the separation process, along with data on suspended solids, BOD, COD, and oil and grease fraction in the raw and treated wastewaters

M. G. Biesinger; I. S. Vining; G. L. Shell

1974-01-01

185

Dissolving polymer microneedle patches for influenza vaccination  

Microsoft Academic Search

Influenza prophylaxis would benefit from a vaccination method enabling simplified logistics and improved immunogenicity without the dangers posed by hypodermic needles. Here we introduce dissolving microneedle patches for influenza vaccination using a simple patch-based system that targets delivery to skin's antigen-presenting cells. Microneedles were fabricated using a biocompatible polymer encapsulating inactivated influenza virus vaccine for insertion and dissolution in the

Sean P Sullivan; Dimitrios G Koutsonanos; Maria del Pilar Martin; Jeong Woo Lee; Vladimir Zarnitsyn; Seong-O Choi; Niren Murthy; Richard W Compans; Ioanna Skountzou; Mark R Prausnitz

2010-01-01

186

An Biogeochemistry of Marine Dissolved Organic Matter  

E-print Network

Carbon Isotopic Composition u The Photochemistry and Cycling of Carbon u Sulfur, Nitrogen and Phosphorus of carbon, phosphorus, nitrogen, and other major elements in the oceans has been a pri- mary goal of marineAn Biogeochemistry of Marine Dissolved Organic Matter Edited by Dennis A. Hansell and Craig A

Hansell, Dennis

187

Dissolved zirconium in the north Pacific Ocean  

SciTech Connect

Picomolar levels of dissolved Zr in seawater were measured using an analytical technique developed with a Chelex-100 extraction/concentration step and subsequent detection by isotope-dilution inductively-coupled-plasma mass spectrometry (ID-ICP-MS). Here the authors present the first vertical profile of Zr in the oceans, from the central-North Pacific, and a horizontal surface transect across the western Pacific. Dissolved Zr ranges from 12--95 pmol/kg in the surface waters then increases linearly with depth to a maximum of 300 pmol/kg in the deep water. The vertical profile shows a strong correlation with Si in the mid-waters, with higher Zr/Si ratios in the surface and bottom waters. There is evidence of both a bottom source and a coastal source of dissolved Zr to the oceans. A comparison with dissolved Ti and Be shows similar depth dependence, but an enrichment in Zr/Ti and a depletion in Zr/Be ratios in seawater relative to average crustal materials. Zirconium appears to have a reactivity intermediate between these two elements. 24 refs., 4 figs., 1 tab.

McKelvey, B.A.; Orians, K.J. (Univ. of British Columbia, Vancouver (Canada))

1993-08-01

188

Modeling Fish Growth in Low Dissolved Oxygen  

ERIC Educational Resources Information Center

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

Neilan, Rachael Miller

2013-01-01

189

DECONTAMINATION OF DISSOLVER VENT GASES AT HANFORD  

Microsoft Academic Search

The dissolver vent gases constitute the most highly contaminated gas ; stream in the present Hanford Separations Plants. From the health hazard ; viewpoint there are two principal contaminants, radio-iodine and an aerosol ; composed of other fission products. An extensive study has been made at Hanford ; of methods and equipment to remove effeciively these materials. Tbis ; investigation

A. G. Blasewitz; R. V. Carlisle; B. F. Judson; M. F. Katzer; E. F. Kurtz; W. C. Schmidt; B. Weidenbaum

1951-01-01

190

Dissolving microneedles for transdermal drug delivery  

Microsoft Academic Search

Microfabrication technology has been adapted to produce micron-scale needles as a safer and painless alternative to hypodermic needle injection, especially for protein biotherapeutics and vaccines. This study presents a design that encapsulates molecules within microneedles that dissolve within the skin for bolus or sustained delivery and leave behind no biohazardous sharp medical waste. A fabrication process was developed based on

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

2008-01-01

191

DISSOLVED OXYGEN IMPACT FROM URBAN STORM RUNOFF  

EPA Science Inventory

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

192

EFFECT OF DISSOLVED ORGANIC SUBSTANCES ON OYSTERS  

E-print Network

EF·FECT OF DISSOLVED ORGANIC SUBSTANCES· ON OYSTERS BY ALBERT COLLIER, S. M. RAY, A. W. MAGNITZKY FISH AND WILDLIFE SERVICE, John L. Farley, Director #12;ABSTRACT Sea. water contains unknown substances of the substances in sea water stored under con- trolled conditions established that light and air increase

193

Fractionation of Dissolved Solutes and Chromophoric Dissolved Organic Matter During Experimental Sea Ice Formation.  

E-print Network

In the past decade there has been an overall decrease in Arctic Ocean sea ice cover. Changes to the ice cover have important consequences for organic carbon cycling, especially over the continental shelves. When sea ice is formed, dissolved organic...

Smith, Stephanie 1990-

2012-04-16

194

Contaminant-mediated photobleaching of wetland chromophoric dissolved organic matter.  

PubMed

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

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

2014-09-20

195

High temperature tests of a JP-5 type fuel. Final report, 20 Sep15 Nov 1972. [Effects of dissolved oxygen  

Microsoft Academic Search

Tests were performed to determine the thermal stability of a JP-5 jet fuel with varying concentrations of dissolved oxygen under supercritical pressure and temperature conditions. Tests were done with the Advanced Aircraft Fuel Systems Simulator using a simulated engine manifold. Small unintentional variations in the test pressure caused large changes in deposit formation rate. These variations obscured any effects of

W. Bucher; R. Bradley

1975-01-01

196

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

SciTech Connect

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.

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

1999-04-01

197

Dissolving polymer microneedle patches for influenza vaccination.  

PubMed

Influenza prophylaxis would benefit from a vaccination method enabling simplified logistics and improved immunogenicity without the dangers posed by hypodermic needles. Here we introduce dissolving microneedle patches for influenza vaccination using a simple patch-based system that targets delivery to skin's antigen-presenting cells. Microneedles were fabricated using a biocompatible polymer encapsulating inactivated influenza virus vaccine for insertion and dissolution in the skin within minutes. Microneedle vaccination generated robust antibody and cellular immune responses in mice that provided complete protection against lethal challenge. Compared to conventional intramuscular injection, microneedle vaccination resulted in more efficient lung virus clearance and enhanced cellular recall responses after challenge. These results suggest that dissolving microneedle patches can provide a new technology for simpler and safer vaccination with improved immunogenicity that could facilitate increased vaccination coverage. PMID:20639891

Sullivan, Sean P; Koutsonanos, Dimitrios G; Del Pilar Martin, Maria; Lee, Jeong Woo; Zarnitsyn, Vladimir; Choi, Seong-O; Murthy, Niren; Compans, Richard W; Skountzou, Ioanna; Prausnitz, Mark R

2010-08-01

198

Upper ocean model of dissolved atmospheric gases  

SciTech Connect

The goal of this project is to estimate the rate of biological oxygen production at Hawaiian Ocean Time-series station ALOHA in the central North Pacific ocean. Our approach is to use an upper ocean model together with measurements to interpret an annual cycle of temperature, salinity, dissolved oxygen, argon, nitrogen, and the stable isotope ratio of oxygen at station ALOHA. This project represents the first upper ocean geochemical study in which model predictions are verifiable by independent measurements. Using the model, we will be able to assess the relative roles played by physical processes (air-sea gas exchange, air injection by bubbles, temperature-induced changes in gas solubility, trapping below the mixed layer, and diffusion) and biological processes (photosynthesis, respiration, and nutrient recycling) in producing the observed distribution of dissolved atmospheric gases. The long term goal of this project is to understand the utility of chemical tracers for quantifying biological processes in the ocean.

Schudlich, R.; Emerson, S.

1992-01-01

199

Dissolved silver in the Baltic Sea.  

PubMed

The increased use of silver as a biocide in nanoparticle formulations has heightened concern on possible environmental implications owing to its toxicity. There is however very little data on the concentration levels of silver in marine and freshwaters. Here, I report data on dissolved (<0.4 ?m filter) silver concentration in the surface waters of the Baltic Sea, the first such data reported for a European coastal water body. Levels of dissolved silver in the Baltic are comparable to those reported for other American estuarine waters and range from non-detectable in the open Baltic Sea Proper (<1 pM) to 9.4 pM (1 ng/L) in the Stockholm Archipelago, with a mean of 2.8 pM (0.2 ng/L). Inputs from wastewater treatment are clearly discernable and might constitute the main source of silver to the Stockholm Archipelago and possibly the Baltic Sea Proper. PMID:21075364

Ndungu, Kuria

2011-01-01

200

Microfabricated solid-state dissolved oxygen sensor  

Microsoft Academic Search

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

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

2002-01-01

201

Boiling of Water Droplets Containing Dissolved Salts  

Microsoft Academic Search

We conducted experiments on the effect of dissolving three different salts (sodium chloride, sodium sulphate and magnesium sulphate) in water droplets boiling on a hot stainless steel surface. Substrate temperatures were varied from 100^oC to 300^oC. We photographed droplets as they evaporated, and recorded their evaporation time. At surface temperatures that were too low to initiate nucleate boiling, all three

Qiang Cui; Sanjeev Chandra; Susan McCahan

2000-01-01

202

Partial nitrification under limited dissolved oxygen conditions  

Microsoft Academic Search

Partial nitrification to nitrite is technically feasible and economically favourable, especially when wastewaters contained high ammonium concentrations or low C\\/N ratios. Partial nitrification can be obtained by selectively inhibiting nitrite-oxidizing bacteria (NOB) through appropriate regulation of the pH, temperature and dissolved oxygen (DO) concentrations. The effect of pH, DO levels and temperature on ammonia oxidation rate and nitrite accumulation was

Wang Jianlong; Yang Ning

2004-01-01

203

Dissolved gases in seawater and sediments  

Microsoft Academic Search

Certainly the most controversial results derived from the study of any dissolved gas concerned oxygen utilization rates in the North Atlantic. Jenkins (1982) estimated a net oxy- gen utilization rate (OUR) for the Beta triangle region of the North Atlantic (apices 26.5°N x 38.5°W, 32.5°N x 30.0°W, and 22.5°N x 28.5°W) of 5.7 moles of oxygen consumed m?2 yr?1 for

R. M. Key

1987-01-01

204

Dissolved oxygen concentrations in hypersaline waters  

Microsoft Academic Search

Henry's law constants (kO) and equilibrium concentrations (CO*) of dissolved oxygen (DO) at 1 atm were measured in NaCl solutions of concentration (S) up to -260%~ and at temperatures (7') between 273 and 308K. An equation of the form In Co* = a, + $ + a,ln T + a,T + a,T2 + S(a, + a,T + a7P) + asS2

J. E. SHERWOOD; F. STAGNITTI; M. J. KOKKINN; W. D. WILLIAMS

1991-01-01

205

How is dissolved iron produced and transported in the Amur River basin?  

NASA Astrophysics Data System (ADS)

Recent research showed that iron limits phytoplankton growth in the western subarctic Pacific and that significant part of it comes from the Amur River, which forms the boundary of China and Russia and finally flows into the Sea of Okhotsk. Our research group confirmed that the crucial processes of producing dissolved iron are reductive release of ferrous iron and formation of iron complex with organic compound in wetland. However, drastic conversion of wetland into cultivated land in China part during the last half of 20th century may have great impact on iron production in the future. To assess the land conversion impact on dissolved iron production, we constructed a semi-distributed hydrological model incorporating dissolved iron production mechanism. The model consists of two modules; one for dealing with the physical process that calculates runoff (TOP- RUNOFF), and the other for dissolved iron production process (TOP-FE). Performance level of TOP- RUNOFF without any calibration assessed by Nash and Sutcliff criteria against observed discharge at several points are fairly well except for catchments affected by anthropogenic impact such as dam. On the basis of TOP-RUNOFF, TOP-FE was formulated as a function of water content, organic compound, air temperature, and one parameter representing the degree of redox condition. Calculated values were compared with observed value at the several tens of points. The result shows that the model reached the level which can predict seasonal trend of dissolved iron concentration. However, the present model can not simulate abrupt increase of dissolved iron concentration which was observed at many points during the late 1990s. Possible reasons of this anomaly are now under consideration. At present, promising reasons are climate change and anthropogenic impact such as agricultural activity, but not yet resolved. Thus, to clarify unknown mechanism which governs the long-term trend of dissolved iron concentration is needed to improve predictability of our model.

Onishi, T.; Yoh, M.; Shibata, H.; Nagao, S.; Kawahigashi, M.

2008-12-01

206

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...

207

Water What-ifs: Water Quality and Dissolved Oxygen  

NSDL National Science Digital Library

This Science Junction website features general information and three lesson plans about dissolved oxygen geared toward middle and high school students. Lessons cover topics such as what dissolved oxygen is, why it is important, and how decomposition of organic material affects dissolved oxygen. The third lesson includes an activity in which students are instructed to design an experiment to test effects of changes in dissolved oxygen concentration. The lessons meet several National Science Education Standards, Delaware science standards, and North Carolina competency goals.

Cleveland, April J.; Science Junction, Nc S.

208

Fluorescent dissolved organic matter in marine sediment pore waters  

E-print Network

Fluorescent dissolved organic matter in marine sediment pore waters David J. Burdige*, Scott W of organic matter diagenesis (e.g., dissolved peptides and proteins) produced near the sediment­water February 2004 Available online 1 June 2004 Abstract Fluorescent dissolved organic matter (FDOM) in sediment

Burdige, David

209

Nature and Transformation of Dissolved Organic Matter in  

E-print Network

, and dissolved oxygen (DO). Water was collected for analysis of total organic carbon (TOC), dissolved (Nature and Transformation of Dissolved Organic Matter in Treatment Wetlands L A R R Y B . B A R B E to become more aromatic and oxygenated. Autochthonous sources are contributed to the DOM, the nature

210

Determination of Dissolved Oxygen in the Cryosphere: A Comprehensive  

E-print Network

Determination of Dissolved Oxygen in the Cryosphere: A Comprehensive Laboratory and Field communities, whose function and dynamics are often controlled by the concentrations of dissolved oxygen (DO tests and superior to traditional methods. Introduction Dissolved oxygen (DO) is a key parameter

Fountain, Andrew G.

211

VARIATIONS IN THE DISSOLVED OXYGEN CONTENT OF INTRAGRAVEL WATER IN  

E-print Network

^402: VARIATIONS IN THE DISSOLVED OXYGEN CONTENT OF INTRAGRAVEL WATER IN FOUR SPAWNING STREAMS IN THE DISSOLVED OXYGEN CONTENT OF INTRAGRAVEL WATER IN FOUR SPAWNING STREAMS OF SOUTHEASTERN ALASKA by William J Introduction 1 Sampling intragravel water for dissolved oxygen content 2 Obtaining water samples from

212

Optical dissolved oxygen sensor utilizing molybdenum chloride cluster phosphorescence  

E-print Network

Optical dissolved oxygen sensor utilizing molybdenum chloride cluster phosphorescence Ruby N. Ghosh collisional quenching, as evidenced by a linear fit to the Stern­Volmer equation for dissolved oxygen of dissolved oxygen DO in aqueous media is necessary for a wide range of chemical and biological processes

Ghosh, Ruby N.

213

Relating dissolved organic matter fluorescence to functional properties  

Microsoft Academic Search

The fluorescence excitation emission matrix properties of dissolved organic matter from three rivers and one lake in NW England are analysed. Sites are sampled in duplicate and for some sites seasonally to cover variations in dissolved organic matter composition, river flow, and carbon isotopic (13C, 14C) variability. Results are compared to the functional properties of the dissolved organic matter, the

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

2007-01-01

214

Temporal dynamics of dissolved combined neutral sugars and the quality of dissolved organic matter in the Northwestern Sargasso Sea  

E-print Network

Temporal dynamics of dissolved combined neutral sugars and the quality of dissolved organic matter) supported its use as a diagenetic indicator of DOM quality. Higher DCNS yields in surface waters suggested quality at this site. & 2008 Elsevier Ltd. All rights reserved. 1. Introduction Dissolved organic matter

California at Santa Barbara, University of

215

The marine geochemistry of dissolved gallium: A comparison with dissolved aluminum  

SciTech Connect

Dissolved Ga concentrations in the pacific Ocean range from 2 to 30 picomolar: they are low in surface waters (2-12 pM), with a subsurface maximum at 150-300 m (6-17 pM), a mid-depth minimum from 500 to 1,000 m (4-10 pM) and increasing values with depth to a maximum in the bottom waters (12-30 pM). The highest concentrations are in the central gyre, with lower values toward the north and east where productivity and particle scavenging increase. Dissolved Ga concentrations in the surface waters of the northwest Atlantic are nearly an order of magnitude higher than in the central North pacific, with higher values in the Gulf Stream than in the continental slope boundary region. The vertical distributions and horizontal transects indicate three sources of dissolved Ga to the oceans. The surface distribution reflects an eolian source with no net fluvial input to the open ocean; the subsurface maximum (a feature not seen for North Pacific dissolved Al) is attributed to vertical exchange processes; the source for the deep waters of the North Pacific is from a sediment surface remineralization process or a pore water flux. Scavenging removal throughout the water column is evident in the vertical profiles for both dissolved Ga and Al, with intensified removal in the boundary regions where productivity and particle scavenging are at a maximum. Residence times of dissolved Ga in surface waters are nearly an order of magnitude longer than the corresponding values for Al.

Orians, K.J.; Bruland, K.W. (Univ. of California, Santa Cruz (USA))

1988-12-01

216

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

SciTech Connect

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

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

2011-12-29

217

Preservation of samples for dissolved mercury  

SciTech Connect

Water samples for dissolved mercury require special treatment because of the high chemical mobility and volatility of this element. Widespread use of mercury and its compounds has provided many avenues for contamination of water. Two laboratory tests were done to determine the relative permeabilities of glass and plastic sample bottles to mercury vapor. Plastic containers were confirmed to be quite permeable to airborne mercury, glass containers were virtually impermeable. Methods of preservation include the use of various combinations of acids, oxidants, and complexing agents. The combination of nitric acid and potassium dichromate successfully preserved mercury in a large variety of concentrations and dissolved forms. Because this acid-oxidant preservative acts as a sink for airborne mercury and plastic containers are permeable to mercury vapor, glass bottles are preferred for sample collection. To maintain a healthy work environment and minimize the potential for contamination of water samples, mercury and its compounds are isolated from the atmosphere while in storage. Concurrently, a program to monitor environmental levels of mercury vapor in areas of potential contamination is needed to define the extent of mercury contamination and to assess the effectiveness of mercury clean-up procedures.

Hamlin, S.N. (Geological Survey, Sacramento, CA (United States))

1989-04-01

218

DISSOLVED CONCENTRATION LIMITS OF RADIOACTIVE ELEMENTS  

SciTech Connect

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.

NA

2004-11-22

219

Mobilisation of Amorphous and Dissolved Silica on Small Agricultural Plots  

NASA Astrophysics Data System (ADS)

In recent years awareness has grown that biogeochemical cycles are strongly affected by processes occurring in the critical zone. Global carbon dynamics, for instance, may be affected by soil erosion and deposition processes that affect carbon dynamics within the critical zone. Silica is another element of which the cycling may be strongly influenced: weathering is a major source of dissolved silica (DSi) that may be transformed to amorphous silica (ASi) through reprecipitation in the soil and/or in vegetation. As Si is a crucial nutrient for diatoms, which are a base component for a well-balanced food-system in estuarine and coastal zones, it is important to understand how anthropogenic modifications of critical-zone processes, including agricultural erosion, may affect global Si cycling. According to our knowledge, studies on the effects of erosion and deposition on Si cycling and mobilisation are almost nonexistent. In this paper we report the first results of a series of rainfall simulation experiments that were set up to (i) quantify Si mobilisation through erosion at the small plot scale and (ii) investigate to what extent Si mobilisation by erosion may be dependent on crop type and tillage technique. We quantified ASi and Dsi fluxes during rainfall experiments on small scale plots (~0.73m2). Experiments are conducted for various crop and tillage types. Our results indicate that soil erosion mobilises significant quantities of ASi and DSi. Overall ASi mobilisation is more important: ca. 80% of total silica export is ASi, only 20% of the Si is exported as dissolved silica. There is a near-linear relationship between ASi and sediment concentration in the runoff: tillage technique and crop type have only a secondary influence. Thus, in a first approximation, a good estimate of ASi mobilisation through erosion can be made if total sediment mobilisation can be correctly assessed.

Clymans, W.; Govers, G.; Struyf, E.; Vandamme, S.; van Wesemael, B.; Langhans, C.; van den Putte, A.; Meire, P.

2009-04-01

220

Benthic foraminiferal dissolved-oxygen index and dissolved-oxygen levels in the modern ocean  

Microsoft Academic Search

Changes in oxygen concentrations at the sediment-water interface play a major role in controlling benthic foraminiferal assemblages and morphologic characteristics; such changes are reflected in size, wall thickness, porosity, and also taxa (genera and species) of foraminifera present. These morphologic and taxonomic differences have been quantified as a dissolved-oxygen index. This paper demonstrates that the foraminiferal oxygen index derived from

Kunio Kaiho

1994-01-01

221

Photochemical and microbial consumption of dissolved organic carbon and dissolved oxygen in the Amazon River system  

NASA Astrophysics Data System (ADS)

Bacterial and photochemical mineralization of dissolved organic matter were investigated in the Amazon River system. Dissolved oxygen, dissolved organic carbon (DOC), and bacterial growth were measured during incubations conducted under natural sunlight and in the dark. Substrate addition experiments indicated that the relatively low rates of bacterial activity in Amazon River water were caused by C limitation. Experiments to determine the photoreactivity of this biologically refractory DOC revealed unusually high rates of photochemical consumption of DOC (~4.0 ?M C h -1) and dissolved oxygen (~3.6 ?M O 2 h -1) in Rio Negro surface waters. In additional experiments we observed that bacterial growth and respiration were not significantly stimulated or inhibited during periods of sunlight exposure. The molar ratio of DOC to O 2 consumed during photochemical processes was close to one (1.11-1.14) in all photooxidation experiments. Sunlight exposure over 27 h showed that at least 15% of Rio Negro DOM was photoreactive. The rate of photochemical consumption of DOC was approximately sevenfold greater than bacterial DOC utilization in Rio Negro surface waters; however, integrated over the entire water column microbial remineralization was the dominant process for oxygen and DOC consumption. Photomineralization of biologically refractory riverine DOM appears to be more important than previously believed and could be a major removal mechanism for terrestrially-derived DOM in the coastal ocean.

Amon, R. M. W.; Benner, R.

1996-05-01

222

Treatment of oil-in-water emulsions by coagulation and dissolved-air flotation  

Microsoft Academic Search

The treatment of oil-in-water emulsions containing n-octane (used as simulated wastewater) was investigated by means of dissolved-air flotation jar-tests. The effect of several parameters on flotation efficiency for separation of the emulsified oil was examined, namely, (a) the presence the nonionic surfactant Tween 80, used for the stabilization of the emulsions, (b) the initial pH value of the emulsions, (c)

A. I Zouboulis; A Avranas

2000-01-01

223

Spawning Success of the Black Crappie, Pomoxis nigromaculatus, at Reduced Dissolved Oxygen Concentrations  

Microsoft Academic Search

Mature black crappies (Pomoxis nigromaculatus) were exposed to constant dissolved oxygen (DO) concentrations near or at 2.5, 3.5, 5.0, or 6.5 mg\\/liter, and near air saturation (control) to determine the effects of reduced DO on spawning success. The fish spawned successfully 39 times in laboratory tanks under a simulated natural temperature and light regime at all DO concentrations tested. Fish

Richard E. Siefert; Lawrence J. Herman

1977-01-01

224

Respiratory Responses of Largemouth Bass (Micropterus salmoides) to Environmental Changes in Temperature and Dissolved Oxygen  

Microsoft Academic Search

Respiratory metabolic rates of largemouth bass, Micropterus salmoides, were measured in flow through respirometers under various temperature and dissolved oxygen conditions simulating drought environments. “Critical” oxygen tensions increased from <40 torr PO2 at 20 C, to 40–50 torr at 25 C, to 50–60 torr at 30 C. Evidence from arterial blood samples indicated increased anaerobic metabolism associated with an oxidative

Joseph J. Cech Jr; Clain G. Campagna; Stephen J. Mitchell

1979-01-01

225

Method for dissolving delta-phase plutonium  

SciTech Connect

A process for dissolving plutonium, and in particular, delta-phase plutonium. The process includes heating a mixture of nitric acid, hydroxylammonium nitrate and potassium fluoride (HAN) to a temperature between 40 and 70 C, then immersing the metal in the mixture. Preferably, the nitric acid has a concentration of not ore than 2M, the HAN approximately 0.66M, and the potassium fluoride 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.

Karraker, D.G.

1992-12-31

226

Fast-response sensors for dissolved oxygen  

NASA Astrophysics Data System (ADS)

In this work we have been developing fast response optical sensors for dissolved oxygen determination based on measuring the luminescence lifetime of a metalloporphyrin polymer. The sensor is produced by electropolymerization of the metalloporphyrin monomer units of platinum tetraphenylporphyrin (Pt-TPP), platinum octaethylporphyrin (Pt-OEP), palladium tetraphenylporphyrin (Pd-TPP) or palladium octaethylporphyrin (Pd-OEP). The polymerization process results in films which are in the region of micrometers thick. The Stern-Volmer quenching constants as determined from luminescence lifetime measurements for these sensors range from 0.90 (mg 1-1)-1) for Pt-TPP to 1.83 (mg 1-1)-1) for Pd-OEP. The response time of these sensors to a step change from an oxygen free to an oxygen saturated solution is in the millisecond region.

Smith, Sheila; Hamill, Alan; Uttamlal, Mahesh; Campbell, Michael; Bailly, David

1999-12-01

227

Removal of dissolved metals by plant tissue  

SciTech Connect

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

Scott, C.D. (Oak Ridge National Lab., TN (United States))

1992-04-25

228

Method for dissolving delta-phase plutonium  

DOEpatents

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.

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

1992-01-01

229

Centrifugo-pneumatic valving utilizing dissolvable films.  

PubMed

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

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

2012-08-21

230

Significant contribution of dissolved organic matter to seawater alkalinity  

NASA Astrophysics Data System (ADS)

The present study shows a previously undocumented role of dissolved organic matter in the marine carbonate system. During photosynthesis, phytoplankton release dissolved organic compounds containing basic functional groups that readily react with protons during seawater titration, and thereby contribute to alkalinity (a measure of buffering capacity). The magnitude of the contribution of dissolved organic compounds to seawater alkalinity is species dependent, suggesting that individual phytoplankton species exude dissolved organic compounds with unique proton accepting capacities. Our study shows that dissolved organic matter produced by marine phytoplankton during photosynthesis is a newly identified buffering component in the ocean, and indicates that the contribution of dissolved organic matter to seawater alkalinity can be significant in the biologically productive upper ocean, where to date it has been unrecognized or considered insignificant.

Kim, Hyun-Cheol; Lee, Kitack

2009-10-01

231

Method to Estimate the Dissolved Air Content in Hydraulic Fluid  

NASA Technical Reports Server (NTRS)

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.

Hauser, Daniel M.

2011-01-01

232

Modeling nitrogen and phosphorus cycles and dissolved oxygen in the Pearl River (Zhujiang) Estuary* I. Model development  

Microsoft Academic Search

In the present study, an ecosystem based water quality model was designed to estimate the biochemical reaction of nutrient and dissolved oxygen in conjunction with a three-dimensional hydrodynamics and sediment model. As both phosphorus and nitrogen successively limit phytoplankton growth in many estuaries, the model simulates both these nutrient cycles using five variables each such as Human activities related to

GUAN Wei-Bing; WONG Lai-Ah; XU Dong-Feng

233

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

EPA Science Inventory

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

234

Boiling of Water Droplets Containing Dissolved Salts  

NASA Astrophysics Data System (ADS)

We conducted experiments on the effect of dissolving three different salts (sodium chloride, sodium sulphate and magnesium sulphate) in water droplets boiling on a hot stainless steel surface. Substrate temperatures were varied from 100^oC to 300^oC. We photographed droplets as they evaporated, and recorded their evaporation time. At surface temperatures that were too low to initiate nucleate boiling, all three salts were found to reduce the evaporation rate since they lower the vapor pressure of water. In the nucleate boiling regime, sodium sulphate and magnesium sulphate enhanced heat transfer because they prevented coalescence of vapor bubbles and produced foaming in the droplet, significantly reducing droplet lifetime. The ability of salts to prevent coalescence is linked to their ionic strength: electric charge accumulated on the surfaces of bubbles produces a repulsive force, preventing them from approaching each other. Sodium chloride, which has a low ionic strength, had little effect on droplet evaporation. Low concentrations (<0.3 mol/liter) of magnesium sulphate enhanced droplet boiling by promoting foaming. However high concentrations (>0.3 mol/liter) reduce droplet evaporation rates by increasing the vapour pressure of water.

Cui, Qiang; Chandra, Sanjeev; McCahan, Susan

2000-11-01

235

Fast dissolving films made of maltodextrins.  

PubMed

This work aimed to study maltodextrins (MDX) with a low dextrose equivalent as film forming material and their application in the design of oral fast-dissolving films. The suitable plasticizer and its concentration were selected on the basis of flexibility, tensile strength and stickiness of MDX films, and the MDX/plasticizer interactions were investigated by ATR-FTIR spectroscopy. Flexible films were obtained by using 16-20% w/w glycerin (GLY). This basic formulation was adapted to the main production technologies, casting and solvent evaporation (Series C) or hot-melt extrusion (Series E), by adding sorbitan monoleate (SO) or cellulose microcrystalline (MCC), respectively. MCC decreased the film ductility and significantly affected the film disintegration time both in vitro and in vivo (Series C<10s; Series E approximately 1min). To assess the film loading capacity, piroxicam (PRX), a water insoluble drug, was selected. The loading of a drug as a powder decreased the film ductility, but the formulation maintained satisfactory flexibility and resistance to elongation for production and packaging procedures. The films present a high loading capacity, up to 25mg for a surface of 6cm(2). The PRX dissolution rate significantly improved in Series C films independently of the PRX/MDX ratio. PMID:18667164

Cilurzo, Francesco; Cupone, Irma E; Minghetti, Paola; Selmin, Francesca; Montanari, Luisa

2008-11-01

236

Determination of dissolved aluminum in water samples  

USGS Publications Warehouse

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)

Afifi, A.A.

1983-01-01

237

Dissolved methane in Indian freshwater reservoirs.  

PubMed

Emission of methane (CH4), a potent greenhouse gas, from tropical reservoirs is of interest because such reservoirs experience conducive conditions for CH4 production through anaerobic microbial activities. It has been suggested that Indian reservoirs have the potential to emit as much as 33.5 MT of CH4 per annum to the atmosphere. However, this estimate is based on assumptions rather than actual measurements. We present here the first data on dissolved CH4 concentrations from eight freshwater reservoirs in India, most of which experience seasonal anaerobic conditions and CH4 buildup in the hypolimnia. However, strong stratification prevents the CH4-rich subsurface layers to ventilate CH4 directly to the atmosphere, and surface water CH4 concentrations in these reservoirs are generally quite low (0.0028-0.305 ?M). Moreover, only in two small reservoirs substantial CH4 accumulation occurred at depths shallower than the level where water is used for power generation and irrigation, and in the only case where measurements were made in the outflowing water, CH4 concentrations were quite low. In conjunction with short periods of CH4 accumulation and generally lower concentrations than previously assumed, our study implies that CH4 emission from Indian reservoirs has been greatly overestimated. PMID:23397538

Narvenkar, G; Naqvi, S W A; Kurian, S; Shenoy, D M; Pratihary, A K; Naik, H; Patil, S; Sarkar, A; Gauns, M

2013-08-01

238

Dissolved Humic Matter in Arctic Estuaries  

NASA Astrophysics Data System (ADS)

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.

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

2002-12-01

239

What controls dissolved iron concentrations in the world ocean?  

Microsoft Academic Search

Dissolved (< 0.4 ?m) iron has been measured in 354 samples at 30 stations in the North and South Pacific, Southern Ocean and North Atlantic by the Trace Metals Laboratory at Moss Landing Marine Laboratories. These stations are all more than 50 km from a continental margin. The global distribution of dissolved iron, which is derived from these profiles, is

Kenneth S. Johnson; R. Michael Gordon; Kenneth H. Coale

1997-01-01

240

Tissue oxygenation with graded dissolved oxygen delivery during cardiopulmonary bypass  

Microsoft Academic Search

Background: Intravascular perfluorochemical emulsions together with a high oxygen tension may increase the delivery of dissolved oxygen to useful levels. The hypothesis of this study is that increasing the dissolved oxygen content of blood with incremental doses of a perfluorochemical emulsion improves tissue oxygenation during cardiopulmonary bypass in a dose-related fashion. Methods and Results: Oxygen utilization was studied in a

William L. Holman; Russell D. Spruell; Edward R. Ferguson; Janice J. Clymer; Walter V. A. Vicente; C. Patrick Murrah; Albert D. Pacifico

1995-01-01

241

ForPeerReview Inversion of Chromophoric Dissolved Organic Matter  

E-print Network

of Chromophoric Dissolved Organic Matter (CDOM) from EO-1 Hyperion Imagery for Turbid Estuarine and Coastal WatersForPeerReview Inversion of Chromophoric Dissolved Organic Matter (CDOM) from EO-1 Hyperion Imagery for Turbid Estuarine and Coastal Waters Journal: Transactions on Geoscience and Remote Sensing Manuscript ID

Yu, Qian

242

Dissolved organic matter in Chesapeake Bay sediment pore waters  

E-print Network

Dissolved organic matter in Chesapeake Bay sediment pore waters David J. Burdige * Department of recent studies of dissolved organic matter (DOM) in Chesapeake Bay sediment pore waters are summar- ized water DOM. This analysis shows that much of the DOM accumulating in sediment pore waters appears

Burdige, David

243

Black Carbon in Estuarine and Coastal Ocean Dissolved Organic Matter  

NASA Technical Reports Server (NTRS)

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.

Mannino, Antonio; Harvey, H. Rodger

2003-01-01

244

Dissolved-Oxygen Requirements of Three Species of Fish  

Microsoft Academic Search

Critical dissolved-oxygen levels and standard metabolic rates were determined for the bluegill, Lepomis macrochirus; largemouth bass, Micropterus salmoides; and the channel catfish, Ictalurus punctatus, at 25° C., 30° C., and 35° C. Two types of experiments were conducted: shock tests in which the dissolved oxygen was dropped rapidly from near saturation to a critically low point; and acclimation tests in

D. D. Moss; D. C. Scott

1961-01-01

245

Enhanced Dissolution of Cinnabar (Mercuric Sulfide) by Dissolved  

E-print Network

Enhanced Dissolution of Cinnabar (Mercuric Sulfide) by Dissolved Organic Matter Isolated from Everglades caused a dramatic increase in mercury release (up to 35 µM total dissolved mercury) from cinnabar). Cinnabar dissolution by isolated organic matter and natural water samples was inhibited by cations

Ryan, Joe

246

Intra-arterial injection of dissolved flunitrazepam tablets.  

PubMed

Intra-arterial application of dissolved tablets is associated with a high risk of tissue necrosis. An early active vasodilatating and recanalising treatment is necessary. We present the case of 21-year-old female who applied three dissolved Flunitrazepam tablets into the ulnar artery and was successfully treated with prostaglandin E1 and recombinant tissue plasminogen activator. PMID:15061050

Pratikto, T H; Strubel, G; Biro, F; Kröger, K

2004-02-01

247

Free Zinc Ion and Dissolved Orthophosphate Effects on  

E-print Network

. This phosphorus-limited lake has been subjected to decades of mining (primarily for zinc and silver) and otherFree Zinc Ion and Dissolved Orthophosphate Effects on Phytoplankton from Coeur d'Alene Lake, Idaho of free (uncomplexed) zinc ion and dissolved- orthophosphate concentrations on phytoplankton that were

248

Interactions of Arsenic and the Dissolved Substances Derived from  

E-print Network

Interactions of Arsenic and the Dissolved Substances Derived from Turf Soils Z H A N G R O N G C H with substances of molecular weight (MW) between 500 and 3500 Da; (3) the association of As and dissolved organic

Florida, University of

249

Dissolved humic substances of the Amazon River system1  

Microsoft Academic Search

Aquatic humic and fulvic acids from nine mainstem and seven major tributary sites in the Amazon River Basin are characterized by their elemental and lignin phenol compositions. Com- bined humic substances represent 60% of the riverine dissolved organic carbon (DOC), with fulvic to humic acid (FA : HA) ratios in the mainstem averaging 4.7 -t 1 .O. All dissolved humic

John R. Ertel; John I. Hedges; Allan H. Devol; Jefrey E. Richey

1986-01-01

250

Dissolved Oxygen in Allen CreekDissolved Oxygen in Allen Creek Dissolved oxygen (DO) enters the water by diffusion from air, as a by-product of photosynthesis and  

E-print Network

Dissolved Oxygen in Allen CreekDissolved Oxygen in Allen Creek Dissolved oxygen (DO) enters Trenk Time of day and dissolved oxygen Background 3/26 4/2 4/9 #12; and rapids. There is an inverse relationship between temperature and DO, i.e. colder water holds more oxygen

Tyler, Christy

251

Before and after studies of the effects of a power plant installation on Lake Lyndon B. Johnson. Nutrient and dissolved oxygen dynamics of a short detention time Texas reservoir. Interim report No. 5  

Microsoft Academic Search

Four different approaches (a nutrient mass balance, a nutrient-phytoplankton simulation model, analytical equations describing turbulent diffusion, and a numeric dissolved oxygen model) were utilized to investigate the nutrient and dissolved oxygen dynamics of Lake Lyndon B. Johnson during 1972 to 1973. The factors that were most important to the modeling of a short detention time impoundment were examined. Based on

J. L. Schnoor; E. G. Fruh

1976-01-01

252

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

USGS Publications Warehouse

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

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

2012-01-01

253

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

NASA Astrophysics Data System (ADS)

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

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

2012-09-01

254

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

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

255

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

PubMed

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

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

2013-01-01

256

Chemical characterization of dissolvable tobacco products promoted to reduce harm.  

PubMed

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

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

2011-03-23

257

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

PubMed

Concentrations of dissolved oxygen (DO) plotted vs. dissolved organic carbon (DOC) in groundwater samples taken from a coastal plain aquifer of South Carolina (SC) showed a statistically significant hyperbolic relationship. In contrast, DO-DOC plots of groundwater samples taken from the eastern San Joaquin Valley of California (CA) showed a random scatter. It was hypothesized that differences in the bioavailability of naturally occurring DOC might contribute to these observations. This hypothesis was examined by comparing nine different biochemical indicators of DOC bioavailability in groundwater sampled from these two systems. Concentrations of DOC, total hydrolysable neutral sugars (THNS), total hydrolysable amino acids (THAA), mole% glycine of THAA, initial bacterial cell counts, bacterial growth rates, and carbon dioxide production/consumption were greater in SC samples relative to CA samples. In contrast, the mole% glucose of THNS and the aromaticity (SUVA(254)) of DOC was greater in CA samples. Each of these indicator parameters were observed to change with depth in the SC system in a manner consistent with active biodegradation. These results are uniformly consistent with the hypothesis that the bioavailability of DOC is greater in SC relative to CA groundwater samples. This, in turn, suggests that the presence/absence of a hyperbolic DO-DOC relationship may be a qualitative indicator of relative DOC bioavailability in groundwater systems. PMID:21707614

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

2012-01-01

258

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

USGS Publications Warehouse

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

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

2012-01-01

259

Chapter A6. Section 6.2. Dissolved Oxygen  

USGS Publications Warehouse

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.

Revised by Lewis, Michael Edward

2006-01-01

260

GLOBE Videos: Hydrology Protocols - Dissolved Oxygen (12:06 min)  

NSDL National Science Digital Library

This video introduces the measurement of dissolved oxygen in a water body as an important indicator of ecosystem health, and demonstrates students analyzing a water sample for dissolved oxygen. The resource includes a video and a written transcript, and is supported by the Dissolved Oxygen Protocol in the GLOBE Teacher's Guide. This is one of seven videos on hydrology in the 24-part instructional video series describing scientific protocols used by GLOBE (Global Learning and Observation to Benefit the Environment), a worldwide, hands-on, K-12 school-based science education program.

261

Dissolved gas and isotopic tracers of denitrification  

SciTech Connect

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

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

2008-02-28

262

Dissolved gaseous mercury behavior in shallow water estuaries  

E-print Network

The formation of dissolved gaseous mercury (DGM) can be an important pathway for mercury removal from an aquatic environment. DGM evasional fluxes from an aquatic system can account for up to 95% of atmospheric Hg and its deposition pathways. While...

Landin, Charles Melchor

2009-05-15

263

The marine biogeochemistry of dissolved and colloidal iron  

E-print Network

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 ...

Fitzsimmons, Jessica Nicole

2013-01-01

264

Microbial production and consumption of marine dissolved organic matter  

E-print Network

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 ...

Becker, Jamie William

2013-01-01

265

Neptunium estimation in dissolver and high-level-waste solutions  

SciTech Connect

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

Pathak, P.N.; Prabhu, D.R.; Kanekar, A.S.; Manchanda, V.K. [Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai - 400 085 (India)

2008-07-01

266

DESIGN PROCEDURES FOR DISSOLVED OXYGEN CONTROL OF ACTIVATED SLUDGE PROCESSES  

EPA Science Inventory

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

267

Integrated sampling and analytical approach for common groundwater dissolved gases.  

PubMed

A novel passive gas diffusion sampler (PGDS) combines sampling, storage and direct injection into a single gas chromatograph (GC). The sampler has a 4.5 mL internal volume when deployed, is easy to operate, and eliminates sample-partitioning. The associated GC method analyzes for a large, dynamic sampling range from a single, small volume injection. Dissolved gases were separated on parallel Rt-Molsieve 5A and Rt-Q-PLOT columns and eluted solutes were quantified using a pulse discharge helium ionization detector (PD-HID). The combined sampling and analytical method appears to be less prone to systematic bias than conventional sampling and headspace partitioning and analysis. Total dissolved gas pressure used in tandem with the PGDS improved the accuracy of dissolved gas concentrations. The incorporation of routine measurements of dissolved biogeochemical and permanent gases into groundwater investigations will provide increased insight into chemical and biological processes in groundwater and improve chemical mass balance accuracy. PMID:18200868

McLeish, Kimberley; Ryan, M Cathryn; Chu, Angus

2007-12-15

268

The effects of dissolved methane upon liquid argon scintillation light  

E-print Network

In this paper we report on measurements of the effects of dissolved methane upon argon scintillation light. We monitor the light yield from an alpha source held 20 cm from a cryogenic photomultiplier tube (PMT) assembly ...

Alexander, T

269

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

EPA Science Inventory

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

270

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 ...

271

Photoreactivity of chromophoric dissolved organic matter transported by the Mackenzie River to the Beaufort Sea  

E-print Network

Photoreactivity of chromophoric dissolved organic matter transported by the Mackenzie River: Chromophoric dissolved organic matter Dissolved organic carbon Photodegradation Mackenzie River Arctic Ocean and min) for the Mackenzie River and a sample from the Mackenzie Shelf. The photoreactivity of Mackenzie

Vincent, Warwick F.

272

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

...amount and quality of dissolved aquatic humic substances...sensitized) photoreaction of dissolved organic chemicals. This reactivity is imparted by dissolved organic material (DOM...intermediates that include singlet oxygen (1 02 )...

2014-07-01

273

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

Code of Federal Regulations, 2013 CFR

...amount and quality of dissolved aquatic humic substances...sensitized) photoreaction of dissolved organic chemicals. This reactivity is imparted by dissolved organic material (DOM...intermediates that include singlet oxygen (1 02 )...

2013-07-01

274

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

Code of Federal Regulations, 2010 CFR

...amount and quality of dissolved aquatic humic substances...sensitized) photoreaction of dissolved organic chemicals. This reactivity is imparted by dissolved organic material (DOM...intermediates that include singlet oxygen (1 02 )...

2010-07-01

275

Population differentiation of the African cyprinid Barbus neumayeri across dissolved oxygen regimes  

E-print Network

Population differentiation of the African cyprinid Barbus neumayeri across dissolved oxygen regimes structure was associated with (i) dissolved oxygen regime (hypoxia or normoxia), (ii) geographical distance, or (iii) a combination of dissolved oxygen regime and geographical distance. Our results indicate

Chapman, Lauren J.

276

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

Code of Federal Regulations, 2012 CFR

...amount and quality of dissolved aquatic humic substances...sensitized) photoreaction of dissolved organic chemicals. This reactivity is imparted by dissolved organic material (DOM...intermediates that include singlet oxygen (1 02 )...

2012-07-01

277

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

Code of Federal Regulations, 2011 CFR

...amount and quality of dissolved aquatic humic substances...sensitized) photoreaction of dissolved organic chemicals. This reactivity is imparted by dissolved organic material (DOM...intermediates that include singlet oxygen (1 02 )...

2011-07-01

278

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

NASA Astrophysics Data System (ADS)

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.

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

279

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

PubMed

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

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

2010-10-21

280

Minerals fractionate and modulate the dissolved organic carbon flux out of marine sediments  

NASA Astrophysics Data System (ADS)

A complex soup of assorted dissolved organic compounds can be found in lakes, rivers and oceans. Some of this organic matter (OM) is associated to mineral phases and the composition of the dissolved organic compound mixture is largely dictated by the adsorption efficacy and availability of mineral surfaces. In sediments, about 90% of the OM is bound - to some extent reversibly - onto minerals, leaving a mere 10% in discrete organic debris [1]. The presence of the sizeable mineral-bound OM pool implies that porewater dissolved organic matter (DOM) concentrations are well buffered by surrounding mineral phases and by the OM that they provisionally retain. We show, through laboratory simulations, that DOM is strongly partitioned between mineral surfaces and ambient waters. Through stable isotope analysis, we demonstrate that the composition of porewater DOM is regulated by an exchange mechanism of organic matter between the solids and the solution. Partitioning is influenced considerably by the mineralogy of the solid phases. In particular, authigenic iron and manganese oxides, formed through diagenetic processes, are typically concentrated at or near the sediment-water interface and increase the efficiency of DOM adsorption. The presence of a strongly sorbing layer located in the uppermost sediment modulates DOM fluxes and causes a strong isotopic (?13C = 3‰), and most likely, a biochemical fractionation of DOM [2]. [1]Hedges & Keil (1995), Marine Chem 49, 81-115. [2] Wang & Druffel (2001), Marine Chem 73, 65-81.

Lalonde, K. M.; Gelinas, Y.; Mucci, A.; Lehman, M.; Panetta, R. J.; Ouellet, A.

2009-12-01

281

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

NASA Astrophysics Data System (ADS)

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

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

2010-10-01

282

Dissolved Oxygen Online Acquisition Terminal Based on Wireless Sensor Network  

Microsoft Academic Search

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

Meijuan Gao; Fan Zhang; Jingwen Tian

2008-01-01

283

Variable gain CMOS potentiostat for dissolved oxygen sensor  

Microsoft Academic Search

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

Mei Yee Ng; Yuzman Yusoff

2010-01-01

284

The Dissolution of Desicooler Residues in H-Canyon Dissolvers  

SciTech Connect

A series of dissolution and characterization studies has been performed to determine if FB-Line residues stored in desicooler containers will dissolve using a modified H-Canyon processing flowsheet. Samples of desicooler materials were used to evaluate dissolving characteristics in the low-molar nitric acid solutions used in H-Canyon dissolvers. The selection for the H-Canyon dissolution of desicooler residues was based on their high-enriched uranium content and trace levels of plutonium. Test results showed that almost all of the enriched uranium will dissolve from the desicooler materials after extended boiling in one molar nitric acid solutions. The residue that contained uranium after completion of the extended boiling cycle consisted of brown solids that had agglomerated into large pieces and were floating on top of the dissolver solution. Addition of tenth molar fluoride to a three molar nitric acid solution containing boron did not dissolve remaining uranium from the brown solids. Only after boiling in an eight molar nitric acid-tenth molar fluoride solution without boron did remaining uranium and aluminum dissolve from the brown solids. The amount of uranium associated with brown solids would be approximately 1.4 percent of the total uranium content of the desicooler materials. The brown solids that remain in the First Uranium Cycle feed will accumulate at the organic/aqueous interface during solvent extraction operations. Most of the undissolved white residue that remained after extended boiling was aluminum oxide containing additional trace quantities of impurities. However, the presence of mercury used in H-Canyon dissolvers should complete the dissolution of these aluminum compounds.

Gray, J.H.

2003-06-23

285

Transport of dissolved salts by bottom density currents  

Microsoft Academic Search

Evolution mechanisms of the concentration fields of dissolved salts transported by density currents were studied in five lowland\\u000a reservoirs and in the latitudinal part of Teletskoe Lake based on data of multicomponent measurements of the distributions\\u000a of current parameters and water composition in longitudinal sections. A mathematical model is proposed for the description\\u000a of dissolved salt transport by these currents.

B. I. Samolyubov; E. S. Afanas’ev

2007-01-01

286

Oxygen isotope fractionation in dissolved oxygen in the deep sea  

Microsoft Academic Search

18O variations in dissolved oxygen have been measured at five stations from the eastern equatorial Pacific, at the GEOSECS-I and -II intercalibration stations in the North Pacific and North Atlantic, and along an Antarctic-South Pacific section from MONSOON expedition. Relative to atmospheric oxygen, dissolved oxygen in the ocean is enriched in 18O up to a maximum of 140\\/00, the extreme

P. Kroopnick; H. Craig

1976-01-01

287

Microbial uptake of dissolved organic matter in Mcmurdo Sound, Antarctica  

Microsoft Academic Search

The distribution and activity of bacterioplankton, and the turnover of dissolved organic matter (DOM) were examined in McMurdo Sound, Antarctica. On the eastern side of the Sound, bacteria averaged 6.5×108 l-1, and turnover rates of dissolved adenosine triphosphate, D-glucose and l-leucine averaged 16, 116 and 124 h, respecitvely. These molecules as well as thymidine were taken up maximally from 0°

R. E. Hodson; F. Azam; A. F. Carlucci; J. A. Fuhrman; D. M. Karl; O. Holm-Hansen

1981-01-01

288

Cellular Partitioning of Nanoparticulate versus Dissolved Metals in Marine Phytoplankton.  

PubMed

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

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

2014-11-18

289

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

SciTech Connect

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.

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

2010-11-30

290

Seasonal Changes in Arctic Dissolved Organic Matter  

NASA Astrophysics Data System (ADS)

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.

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

2011-12-01

291

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

PubMed

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

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

2010-08-11

292

Dissolved Organic Matter in the Hudson River Plume  

NASA Astrophysics Data System (ADS)

As part of the LATTE (Lagrangian Transport and Transformation Experiment) program, dissolved organic carbon (DOC), total nitrogen (TN), and chromophoric dissolved organic matter (CDOM) were measured in the Hudson River Estuary and Plume. As revealed by high resolution measurements from the Integrated Coastal Observation System (ICOS), dissolved organic matter has several sources within the estuary including the Hudson and Raritan Rivers, and a yet unidentified anthropogenic source off Manhattan. The quantity of dissolved organic matter that is exported from the Hudson River Estuary is significantly greater than that which the Hudson River can supply by simply conservative mixing with coastal seawater. In May, 2004, rhodamine dye was injected at the surface as the plume flowed out onto the New York/New Jersey shelf, once as the plume turned north towards Long Island, and once as the plume flowed south along the New Jersey coast. The ECOShuttle (a towed-undulating vehicle) carrying a rhodamine fluorometer was able to track these dye patches. An examination of dissolved organic matter transformations that occurred over these two to two and one-half day Lagrangian experiments will be discussed. In addition seasonal distributions of dissolved organic matter distributions will be presented from cruises in June 2003, June 2004 and September 2004 under different river flow and wind conditions.

Chen, R. F.; Gardner, G. B.

2004-12-01

293

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

USGS Publications Warehouse

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)

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

1987-01-01

294

Microfluidic dissolved oxygen gradient generator biochip as a useful tool in bacterial biofilm studies.  

PubMed

A microfluidic chip for generation of gradients of dissolved oxygen was designed, fabricated and tested. The novel way of active oxygen depletion through a gas permeable membrane was applied. Numerical simulations for generation of O(2) gradients were correlated with measured oxygen concentrations. The developed microsystem was used to study growth patterns of the bacterium Pseudomonas aeruginosa in medium with different oxygen concentrations. The results showed that attachment of Pseudomonas aeruginosa to the substrate changed with oxygen concentration. This demonstrates that the device can be used for studies requiring controlled oxygen levels and for future studies of microaerobic and anaerobic conditions. PMID:20571689

Skolimowski, Maciej; Nielsen, Martin Weiss; Emnéus, Jenny; Molin, Søren; Taboryski, Rafael; Sternberg, Claus; Dufva, Martin; Geschke, Oliver

2010-08-21

295

Efficient and facile delivery of gold nanoparticles in vivo using dissolvable microneedles for  

E-print Network

Efficient and facile delivery of gold nanoparticles in vivo using dissolvable microneedles in aqueous dissolvable microneedles (dMNs; 200 µm height) for efficient, precisely controlled, and convenient

Chen, Zhongping

296

Photochemical Degradation of Persistent Organic Pollutants: A Study of Ice Photochemistry Mediated by Dissolved Organic Matter  

NASA Astrophysics Data System (ADS)

It is well established that ice is a reactive medium in the environment and that active photochemistry occurs in frozen systems. Snow and ice contain a number of absorbing species including nitrate, peroxide and organic matter. Upon irradiation, they can generate a variety of reactive intermediates such as hydroxyl radical and singlet oxygen. It has been shown that dissolved organic matter is a ubiquitous component of snow and ice and plays an important role in overall light absorption properties of the sample. Additionally, the reactive intermediates produced can further react with contaminants present and alter their fate in the environment. Unfortunately, the role of dissolved organic matter in ice photochemistry has received little attention. Here we present results from laboratory-based studies aimed at elucidating the role of dissolved organic matter photochemistry on contaminant degradation in ice. Aqueous samples of our target pollutant, aldrin (20 ?g/L), in liquid and frozen phases, were irradiated under Q-Panel 340 lamps to simulate the UV radiation profile of natural sunlight. Results indicated that frozen samples degraded more quickly than liquid samples and that the addition of dissolved organic matter increases the aldrin degradation rate significantly. Both terrestrial (Suwannee River, U.S.) and microbial sources (Pony Lake, Antarctica) of DOM were able to sensitize aldrin loss in ice. Scavengers of singlet oxygen, such as furfuryl alcohol and ?-carotene, were also added to DOM solutions. Based on the type of organic matter present, the scavengers had different effects on the photochemical degradation of aldrin. Our results indicate that natural organic matter present in ice is an important component of ice photochemical processes.

Bobby, R.; Pagano, L.; Grannas, A. M.

2012-12-01

297

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

NASA Astrophysics Data System (ADS)

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

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

2010-05-01

298

Actinide partitioning studies using dihexyl-N,N-diethycarbamolymehtyl phosphonate and dissolved zirconium calcine  

SciTech Connect

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.

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

1996-01-01

299

Using dissolved oxygen and dissolved inorganic carbon stable isotopes to investigate O2 dynamics in a shallow groundwater system  

Microsoft Academic Search

Dissolved oxygen (DO) concentration is often one of the major determinants of the geochemistry and microbiology of shallow aquifer systems. DO is often consumed along groundwater flow paths but, the processes that use DO (e.g., biological or inorganic) are often unclear. The use of stable isotopes of molecular O2 (delta18O-DO) in conjunction with the stable isotope composition of dissolved inorganic

S. Parker; G. Smith; C. Gammons; S. R. Poulson

2009-01-01

300

K Basin Sludge Conditioning Process Testing Partitioning of PCBs in Dissolver Solution After Neutralization/Precipitation (Caustic Adjustment)  

SciTech Connect

The purpose of the work described in this report was to gain a better understanding of how PCB congeners present in a simulated K Basin sludge dissolver solution will partition upon neutralization and precipitation (i.e., caustic adjustment). In a previous study (Mong et al. 1998),the entire series of sludge conditioning steps (acid dissolution, filtration, and caustic adjustment) were examined during integrated testing. In the work described here, the caustic adjustment step was isolated to examine the fate of PCBs in more detail within this processing step. For this testing, solutions of dissolver simulant (containing no solids) with a known initial concentration of PCB congeners were neutralized with caustic to generate a clarified supernatant and a settled sludge phase. PCBs were quantified in each phase (including the PCBs associated with the test vessel rinsates), and material balance information was collected.

Schmidt, A.J.; Thornton, B.M.; Hoppe, E.W.; Mong, G.M.; Silvers, K.L.; Slate, S.O.

1999-01-04

301

Quantification of dissolved iron sources to the North Atlantic Ocean  

NASA Astrophysics Data System (ADS)

Dissolved iron is an essential micronutrient for marine phytoplankton, and its availability controls patterns of primary productivity and carbon cycling throughout the oceans. The relative importance of different sources of iron to the oceans is not well known, however, and flux estimates from atmospheric dust, hydrothermal vents and oceanic sediments vary by orders of magnitude. Here we present a high-resolution transect of dissolved stable iron isotope ratios (?56Fe) and iron concentrations ([Fe]) along a section of the North Atlantic Ocean. The different iron sources can be identified by their unique ?56Fe signatures, which persist throughout the water column. This allows us to calculate the relative contribution from dust, hydrothermal venting and reductive and non-reductive sedimentary release to the dissolved phase. We find that Saharan dust aerosol is the dominant source of dissolved iron along the section, contributing 71-87 per cent of dissolved iron. Additional sources of iron are non-reductive release from oxygenated sediments on the North American margin (10-19 per cent), reductive sedimentary dissolution on the African margin (1-4 per cent) and hydrothermal venting at the Mid-Atlantic Ridge (2-6 per cent). Our data also indicate that hydrothermal vents in the North Atlantic are a source of isotopically light iron, which travels thousands of kilometres from vent sites, potentially influencing surface productivity. Changes in the relative importance of the different iron sources through time may affect interactions between the carbon cycle and climate.

Conway, Tim M.; John, Seth G.

2014-07-01

302

Quantification of dissolved iron sources to the North Atlantic Ocean.  

PubMed

Dissolved iron is an essential micronutrient for marine phytoplankton, and its availability controls patterns of primary productivity and carbon cycling throughout the oceans. The relative importance of different sources of iron to the oceans is not well known, however, and flux estimates from atmospheric dust, hydrothermal vents and oceanic sediments vary by orders of magnitude. Here we present a high-resolution transect of dissolved stable iron isotope ratios (?(56)Fe) and iron concentrations ([Fe]) along a section of the North Atlantic Ocean. The different iron sources can be identified by their unique ?(56)Fe signatures, which persist throughout the water column. This allows us to calculate the relative contribution from dust, hydrothermal venting and reductive and non-reductive sedimentary release to the dissolved phase. We find that Saharan dust aerosol is the dominant source of dissolved iron along the section, contributing 71-87 per cent of dissolved iron. Additional sources of iron are non-reductive release from oxygenated sediments on the North American margin (10-19 per cent), reductive sedimentary dissolution on the African margin (1-4 per cent) and hydrothermal venting at the Mid-Atlantic Ridge (2-6 per cent). Our data also indicate that hydrothermal vents in the North Atlantic are a source of isotopically light iron, which travels thousands of kilometres from vent sites, potentially influencing surface productivity. Changes in the relative importance of the different iron sources through time may affect interactions between the carbon cycle and climate. PMID:25008528

Conway, Tim M; John, Seth G

2014-07-10

303

Effect of Long-term Reduction and Diel Fluctuation in Dissolved Oxygen on Spawning of Black Crappie, Pomoxis nigromaculatus  

Microsoft Academic Search

Mature black crappies were exposed over winter in the laboratory to constant dissolved oxygen concentrations near 2.5, 4.0, 5.5, and 7.0 mg\\/liter. Starting on 26 April during a simulated spring-to-summer rise in water temperature, some were continued at the original oxygen concentrations while others were subjected to mean diel fluctuations ranging from 0.8 to 1.9 mg O2\\/liter above and below

Anthony R. Carlson; Lawrence J. Herman

1978-01-01

304

The Double Solid Reactant Method for modeling the release of trace elements from dissolving solid phases: I. Outline and limitations  

Microsoft Academic Search

A Double Solid Reactant Method was elaborated from a suggestion of Marini (Geological sequestration of carbon dioxide: Thermodynamics,\\u000a kinetics, and reaction path modeling. Developments in Geochemistry, Elsevier, Amsterdam, 2007) to simulate the release of\\u000a trace elements during the progressive dissolution of solid phases. The method is based on the definition, for each dissolving\\u000a solid, of both an entity whose thermodynamic

Marina Accornero; Luigi Marini

2008-01-01

305

Removal of dissolved organic matter by anion exchange: Effect of dissolved organic matter properties  

USGS Publications Warehouse

Ten isolates of aquatic dissolved organic matter (DOM) were evaluated to determine the effect that chemical properties of the DOM, such as charge density, aromaticity, and molecular weight, have on DOM removal by anion exchange. The DOM isolates were characterized asterrestrial, microbial, or intermediate humic substances or transphilic acids. All anion exchange experiments were conducted using a magnetic ion exchange (MIEX) resin. The charge density of the DOM isolates, determined by direct potentiometric titration, was fundamental to quantifying the stoichiometry of the anion exchange mechanism. The results clearly show that all DOM isolates were removed by anion exchange; however, differences among the DOM isolates did influence their removal by MIEX resin. In particular, MIEX resin had the greatest affinity for DOM with high charge density and the least affinity for DOM with low charge density and low aromaticity. This work illustrates that the chemical characteristics of DOM and solution conditions must be considered when evaluating anion exchange treatment for the removal of DOM. ?? 2008 American Chemical Society.

Boyer, T. H.; Singer, P. C.; Aiken, G. R.

2008-01-01

306

Photochemical production of dissolved inorganic carbon from suwannee river humic acid  

NASA Astrophysics Data System (ADS)

The photochemical mineralization of dissolved organic carbon (DOC) to dissolved inorganic carbon (DIC) is a key process in carbon cycling. Using a Suntest CPS solar simulator, Suwannee River humic acid (SRHA) was photooxidated to examine the effects of O2 levels, the wavelength of incident light, and the concentration of Fe on the photoproduction of DIC. Increasing the O2 abundance enhanced photodegradation of SRHA. The rate of DIC photoproduction under air saturation in the first 24 h (4.40 µmol/(L h)) was increased by a factor of 1.56 under O2 saturation, but fell by only 36% under N2 saturation. To evaluate the relative importance of UV-B, UV-A, and visible radiation in the photodegradation, we examined the above process using Mylar-d films and UF-3 and UF-4 plexiglass filters. The results indicated that the UV-B, UV-A and visible wavelengths accounted for 31.8%, 32.6% and 25.6%, respectively, of DIC production with simulated sunlight irradiation. The above results also indicated that photoproduction of DIC could take place in natural water at depths greater than those that UV light can reach. When 20 µmol/L desferrioxamine mesylate (DFOM, a strong Fe complexing ligand) was added, the rate of DIC photoproduction fell to 55.6% that of the original SRHA samples with 5.46 µmol/L Fe.

Wang, Xuejun; Lou, Tao; Xie, Huixiang

2009-09-01

307

Time Series Stream Temperature And Dissolved Oxygen Modeling In The Lower Flint River Basin  

NASA Astrophysics Data System (ADS)

The tributaries of the Lower Flint River Basin (LFRB) are incised into the upper Floridan semi-confined limestone aquifer, and thus seepage of relatively old groundwater sustains baseflows and provides some control over temperature and dissolved oxygen fluctuations. This hydrologic and geologic setting creates aquatic habitat that is unique in the state of Georgia. Groundwater withdrawals and possible water supply reservoirs threaten to exacerbate low flow conditions during summer droughts, which may force negative impacts to stream temperature and dissolved oxygen (DO). To evaluate the possible effects of human modifications to stream habitat, summer time series (in 15 min interval) of stream temperature and DO were monitored over the last three years along these streams, and a Continuously Stirred Tank Reactor (CSTR) model was developed and calibrated with these data. The driving forces of the diel trends and the overall levels of stream temperature and DO were identified by this model. Simulations were conducted with assumed managed flow conditions to illustrate potential effects of various stream flow regimes on stream temperature and DO time series. The goal of this research is to provide an accurate simulation tool to guide management decisions.

Li, G.; Jackson, C. R.

2004-12-01

308

Dissolved Oxygen for Fish Production1 Ruth Francis-Floyd2  

E-print Network

FA27 Dissolved Oxygen for Fish Production1 Ruth Francis-Floyd2 1. This document is FA27, one Commissioners Cooperating. Millie Ferrer-Chancy, Interim Dean What Is Dissolved Oxygen? Dissolved oxygen (DO. Sensitivity to low levels of dissolved oxygen is species specific, however, most species of fish

Watson, Craig A.

309

Formulation development and evaluation of fast dissolving film of telmisartan.  

PubMed

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

Londhe, Vaishali Y; Umalkar, Kashmira B

2012-03-01

310

Dissolved and bioavailable contaminants in the Seine river basin.  

PubMed

Diffusive Gradient in Thin Films (DGT) and Semi-Permeable Membrane Devices (SPMDs) were deployed in the Seine river basin in order to assess labile metals and truly dissolved Polycyclic Aromatic Hydrocarbons. We show that the tools are reliable in aquatic environments to assess the speciation of dissolved contaminants and hence provide a good insight into the potential bioavailability of contaminants. The deployment of the DGT and SPMDs in contrasting environments in the Seine river basin allowed distinction to be made of availability of contaminants between headwater streams and much more impacted river reaches and an assessment of bioavailability. At the stations under urban influence, the impact of dissolved organic matter on both copper and PAHs bioavailability is less pronounced than at upstream stations, where humic substances dominate. PMID:17276495

Tusseau-Vuillemin, Marie-Hélène; Gourlay, Catherine; Lorgeoux, Catherine; Mouchel, Jean-Marie; Buzier, Rémy; Gilbin, Rodolphe; Seidel, Jean-Luc; Elbaz-Poulichet, Françoise

2007-04-01

311

Dissolved mercury behaviour in the Saint Lawrence estuary  

NASA Astrophysics Data System (ADS)

Dissolved mercury concentrations have been measured in the waters of the St Lawrence estuary. The typical concentration of the riverine end-member is 12·0±3·0 p M; the oceanic end-member samples exhibit a mean mercury concentration of 2·4 p M. The graphical pattern of the relationship between mercury concentration and salinity shows a departure from a dilution line. We suggest that a removal of mercury from the dissolved phase during the estuarine mixing is responsible for this observation. Based on the results, the actual input of dissolved mercury from the St Lawrence River to the Gulf is evaluated to be approximately 0·52 T a -1.

Cossa, Daniel; Gobeil, Charles; Courau, Philippe

1988-02-01

312

Effects of dissolved organic matter from a eutrophic lake on the freely dissolved concentrations of emerging organic contaminants.  

PubMed

The authors studied the effects of dissolved organic matter (DOM) on the bioavailability of bisphenol A (BPA) and chloramphenicol by measuring the freely dissolved concentrations of the contaminants in solutions containing DOM that had been isolated from a mesocosm in a eutrophic lake. The abundance and aromaticity of the chromophoric DOM increased over the 25-d mesocosm experiment. The BPA freely dissolved concentration was 72.3% lower and the chloramphenicol freely dissolved concentration was 56.2% lower using DOM collected on day 25 than using DOM collected on day 1 of the mesocosm experiment. The freely dissolved concentrations negatively correlated with the ultraviolent absorption coefficient at 254 nm and positively correlated with the spectral slope of chromophoric DOM, suggesting that the bioavailability of these emerging organic contaminants depends on the characteristics of the DOM present. The DOM-water partition coefficients (log KOC ) for the emerging organic contaminants positively correlated with the aromaticity of the DOM, measured as humic acid-like fluorescent components C1 (excitation/emission=250[313]/412 nm) and C2 (excitation/emission=268[379]/456 nm). The authors conclude that the bioavailability of emerging organic contaminants in eutrophic lakes can be affected by changes in the DOM. PMID:24839192

Xiao, Yi-Hua; Huang, Qing-Hui; Vähätalo, Anssi V; Li, Fei-Peng; Chen, Ling

2014-08-01

313

New potentiomentric dissolved oxygen sensors in thick film technology  

Microsoft Academic Search

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

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

2004-01-01

314

Thermodynamic properties of gases dissolved in electrolyte solutions.  

NASA Technical Reports Server (NTRS)

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.

Tiepel, E. W.; Gubbins, K. E.

1973-01-01

315

Modelling dissolved oxygen and benthic algae dynamics in a coastal ecosystem by exploiting real-time monitoring data  

NASA Astrophysics Data System (ADS)

In this work we propose a methodological approach for the detection and simulation of relevant changes in coastal ecosystems, i.e. oxygen depletion and proliferation of benthic algae. This approach is based on the integration of the data provided by real-time monitoring systems with the output of complex ecosystem models. We tested the method in a case study, where real-time Dissolved Oxygen (DO) data and a 2D Reaction-Transport model were used to simulate the growth of macroalgae and the daily dynamics of DO in the Lagoon of Venice (Italy). The spatiotemporal relationships among the macroalgae distribution and the DO observations were quantified by analysing and comparing the Dissolved Oxygen time series and model outputs. The outcomes were used for the inverse estimation of the initial, i.e. late winter, biomass of macroalgae. The model was then applied to simulate the growth of macroalgae and the daily dynamic of DO during the productive (i.e., spring and summer) seasons. The comparison between the model output and the real-time data indicates that the model had skill in simulating the short term (daily) DO dynamic at several lagoon sites impacted by macroalgae proliferation. The simulated intra-daily variability of Dissolved Oxygen is significantly correlated with the observations in half of the monitoring sites, as well the simulated algal growth, which resulted comparable with the field measurements. The estimated average value of macroalgae biomass was ˜1 kgfw m-2 in 2007, which is consistent with a good to moderate quality status of the Lagoon of Venice. The proposed methodology can be useful in the assessment of the environmental status of coastal ecosystems as required by recent national and international legislation.

Lovato, T.; Ciavatta, S.; Brigolin, D.; Rubino, A.; Pastres, R.

2013-03-01

316

Dissolved, Exsolved and Re-dissolved H2O in Volcanology: Rheology, Glass Transition, and Thermodynamics  

NASA Astrophysics Data System (ADS)

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.

Russell, K.; kennedy, B.; Giordano, D.; Friedlander, E. A.

2012-12-01

317

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

Microsoft Academic Search

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

Hyeog-Chan Kwon

2002-01-01

318

Large fluctuations of dissolved oxygen in the Indian and Pacific oceans during Dansgaard-Oeschger oscillations caused by variations of North Atlantic Deep Water subduction  

Microsoft Academic Search

Paleoclimate records from glacial Indian and Pacific oceans sediments document millennial-scale fluctuations of subsurface dissolved oxygen levels and denitrification coherent with North Atlantic temperature oscillations. Yet the mechanism of this teleconnection between the remote ocean basins remains elusive. Here we present model simulations of the oxygen and nitrogen cycles that explain how changes in deepwater subduction in the North Atlantic

Andreas Schmittner; Eric D. Galbraith; Steven W. Hostetler; Thomas F. Pedersen; Rong Zhang

2007-01-01

319

Micromachined dissolved oxygen sensor based on solid polymer electrolyte  

Microsoft Academic Search

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

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

2011-01-01

320

Dissolved oxygen modeling of the Blackstone River (northeastern United States)  

Microsoft Academic Search

A dissolved oxygen model, QUAL2E, has been calibrated and validated to the Blackstone River, using the data collected in 1991 for the Blackstone River Initiative — Dry Weather Study. Physical representation of the river is accomplished using the data from previous studies. Flow profiles have been developed using the average daily flows of the three permanent United States Geological Survey

Rajat R. Chaudhury; Jose A. H. Sobrinho; Raymond M. Wright; Makam Sreenivas

1998-01-01

321

Development of a reliable microelectrode dissolved oxygen sensor  

Microsoft Academic Search

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

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

2007-01-01

322

Atmospheric inputs and river transport of dissolved substances  

Microsoft Academic Search

Several different types of behaviour can be observed for elements between atmospheric input and river transport including very limited chemical or biological reactivity (CI-, in most cases), change of speciation (C, N, P), recycling to atmosphere (C, N, S, K), increase of dissolved contents through weathering (Si, Ca, Mg, Na), and build-up in soil or vegetation (C, N, P, Ca,

MICHEL MEYBECK

1983-01-01

323

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...

324

Laser remote sensing of dissolved organic matter in natural water  

Microsoft Academic Search

Fluorescent methods using Raman scattering signal as an internal standard are widely applied for environment remote control of dissolved organic matter (DOM) in water. In this paper temperature variations, ultraviolet irradiation influence on exitation and emission spectra of water samples have been investigated. Photochemical processes in DOM under laser excitation and the effect of fluorescence saturation have been studied

V. V. Chubarov; V. V. Fadeev; E. M. Filippova

1993-01-01

325

Determination of suspended and dissolved uranium in water  

Microsoft Academic Search

Individual droplets of water can be analyzed for uranium down to less than 0.01 ..mu..g\\/l. using readily available neutron doses. By separately counting randomly arrayed and clustered tracks, the dissolved uranium can be separated from that which is suspended in particulate matter. (auth)

R. L. Fleischer; A. C. Delany

1976-01-01

326

DISSOLVED OXYGEN MEASUREMENTS IN OHIO STREAMS FOLLOWING URBAN RUNOFF  

EPA Science Inventory

Thirteen towns and cities in Ohio, situated on streams and rivers having different mean daily flow rates, were investigated during the summer and spring of 1977 to determine their suitability as sites for more extensive field studies on the impacts of urban runoff on dissolved ox...

327

Transformer Fault Diagnosis by Dissolved-Gas Analysis  

Microsoft Academic Search

The great majority of incipient faults occurring in power transformers gives evidence of their presence early in their developmental stages. Oil and oil-impregnated electrical insulating materials can decompose under the influence of thermal and electrical stresses generating gaseous decomposition products which dissolve in the mineral oil. The nature and the amount of the individual component gases extracted from the oil

Joseph J. Kelly

1980-01-01

328

The Dissolved Oxygen Controversy: Reconciling Oceanographic Versus Geological Perspectives  

Microsoft Academic Search

Geological models for the origin of black shales have invoked a preservative effect of dysoxia-anoxia for nearly a century, yet during the last 30 years some oceanographers have used modern sediment data to question and even deny the importance of dissolved oxygen. This schism over the origin of organic-rich sediments must be addressed and healed. With regard to modern sediment

R. V. Tyson

2003-01-01

329

Primary production in the Arctic Ocean estimated from dissolved oxygen  

Microsoft Academic Search

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

Lawrence R. Pomeroy

1997-01-01

330

Dissolved silica dynamics and phytoplankton population in Citarum watershed, Indonesia  

Microsoft Academic Search

Silicon is an essential and beneficial nutrient for aquatic and terrestrial primary producers, respectively. Previous research reported that low silica available in lowland sawahs (a leveled and bounded rice field with an inlet and outlet for irrigation and drainage) in the Citarum watershed was partially associated with low dissolved silica (DSi) concentrations in irrigation water. DSi dynamics and the effect

Toshiyuki Wakatsuki

2009-01-01

331

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...

332

Truth-Theoretic Contextualism: Dissolving the Minimalism\\/Contextualism Debate  

Microsoft Academic Search

Truth-Theoretic Contextualism: Dissolving the Minimalism\\/Contextualism Debate Wouter Beek Abstract: The scope of the research field of semantics seems to shrink in the recent debate between the viewpoints of contextualism and (semantic) minimalism. Minimalists hold that semantics is the formal endeavour that derives a minimal proposition from the syntactically structured input string. This semantic content is then fed to the subsequent

Wouter Beek

2009-01-01

333

Chloride Analysis of RFSA Second Campaign Dissolver Solution  

SciTech Connect

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.

Holcomb, H.P.

2001-05-17

334

Dissolved oxygen concentration profiles in a production-scale bioreactor  

Microsoft Academic Search

A five-compartment model for the liquid flow and the oxygen transfer into the liquid phase of a large-scale bioreactor is presented. The aim of the model is to predict the following reactor operating variables: 1) the overall oxygen transfer capacity of the reactor; 2) the local liquid dissolved oxygen concentrations, for estimation of bad aerated zones which can introduce negative

N. M. G. Oosterhuis; N. W. F. Kossen

1984-01-01

335

MICRO GASOMETRIC DETERMINATION OF DISSOLVED OXYGEN AND NITROGEN  

Microsoft Academic Search

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

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

336

Investigating Factors that Affect Dissolved Oxygen Concentration in Water  

ERIC Educational Resources Information Center

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)

Jantzen, Paul G.

1978-01-01

337

The Minnesota Filter: A Tool for Capturing Stormwater Dissolved Phosphorus  

E-print Network

The Minnesota Filter: A Tool for Capturing Stormwater Dissolved Phosphorus Andy Erickson, Research (inorganic, organic) · Nutrients (nitrogen, phosphorus, etc.) · Metals (copper, cadmium, zinc, etc.N., Smith, S.J., Jones, O.R., Berg, W.A. and Coleman, G.A. (1992) The Transport of Bioavailable Phosphorus

Minnesota, University of

338

Microbial utilization of dissolved organic carbon leached from riparian litterfall  

Microsoft Academic Search

Dissolved organic carbon (DOC) in aquatic systems is abundant and used within stream food webs, but DOC quality is rarely studied. DOC in the leachates from the litter of five tree species (red alder, Alnus rubra; vine maple, Acer circinatum; western red cedar, Thuja plicata; western hemlock, Tsuga hetrophylla; and Douglas-fir, Pseudotsuga menziesii) were assessed for their chemistry and relative

Michael D. McArthur; John S. Richardson

2002-01-01

339

DISSOLVED OXYGEN AND OXIDATION-REDUCTION POTENTIALS IN GROUND WATER  

EPA Science Inventory

Water samples were collected from various depths in a pristine sand and gravel water table aquifer at monthly intervals over a period of one year. Dissolved oxygen concentrations were near saturation 9 feet below the water table and decreased to nearly zero at 78 feet below the w...

340

Composition, Dynamics, and Fate of Leached Dissolved Organic Matter  

E-print Network

Composition, Dynamics, and Fate of Leached Dissolved Organic Matter in Terrestrial Ecosystems of plant-litter leachate as a vehicle for DOM movement, and to track DOM decomposition [in- cluding and isotopic dynamics, during a long-term laboratory incubation experiment using fresh leaves and litter from

Neff, Jason

341

Leachability of dissolved chromium in asphalt and concrete surfacing materials  

Microsoft Academic Search

Leachate metal pollutant concentrations produced from different asphalt and concrete pavement surfacing materials were measured under controlled laboratory conditions. The results showed that, in general, the concentrations of most metal pollutants were below the reporting limits. However, dissolved chromium was detected in leachate from concrete (but not asphalt) specimens and more strongly in the early-time leachate samples. As the leaching

Masoud Kayhanian; Akshay Vichare; Peter G. Green; John Harvey

2009-01-01

342

Relatin Dissolved Oxygen Concentration to Fish Distribution in Jarecki Lake  

Microsoft Academic Search

\\u0009Water temperature and dissolved oxygen (DO) profiles were measured once every month from mid July to mid February in a relatively deep sand-pit lake in southeast Nebraska. These profiles showed depleted DO concentrations below the thermocline during summer stratification indicating areas fish will likely avoid in summer months. Colder temperatures in fall caused complete mixing of the water column allowing

Adam Sutton

2010-01-01

343

Short time dissolved oxygen dynamics in shallow water ecosystems  

Microsoft Academic Search

Dissolved oxygen evolution over time holds information about the recent and past history of the physics, the chemistry and the biology of aquatic systems. On the daily time scale various phenomena seem to repeat with a sort of regularity, leaving a trace in the further trend of oxygen dynamics. These are the wind calm of nocturnal and early morning hours,

Roberto D’Autilia; Margherita Falcucci; Vincent Hull; Luisa Parrella

2004-01-01

344

Degradation of Dissolved Organic Carbon in Permeable Coastal Sediments  

Microsoft Academic Search

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

Lindsay Chipman

2008-01-01

345

Dissolved Organic Matter and Emerging Contaminants in Urban Stream Ecosystems  

NASA Astrophysics Data System (ADS)

We investigated the effects of urbanization on the sources, bioavailability and forms of natural and anthropogenic organic matter found in streams located in Maryland, U.S.A. We found that the abundance, biaoavailability, and enzymatic breakdown of dissolved organic carbon (DOC), dissolved organic nitrogen (DON), and dissolved organic phosphorus (DOP) increased in streams with increasing watershed urbanization suggesting that organic nutrients may represent a growing form of nutrient loading to coastal waters associated with land use change. Organic carbon, nitrogen, and phosphorus in urban streams were elevated several-fold compared to forest and agricultural streams. Enzymatic activities of stream microbes in organic matter decomposition were also significantly altered across watershed land use. Chemical characterization suggested that organic matter in urban streams originated from a variety of sources including terrestrial, sewage, and in-stream transformation. In addition, a characterization of emerging organic contaminants (polyaromatic cyclic hydrocarbons, organochlorine pesticides, and polybrominated diphenyl ether flame retardents), showed that organic contaminants and dissolved organic matter increase with watershed urbanization and fluctuate substantially with changing climatic conditions. Elucidating the emerging influence of urbanization on sources, transport, and in-stream transformation of organic nutrients and contaminants will be critical in unraveling the changing role of organic matter in urban degraded and restored stream ecosystems.

Kaushal, S. S.; Findlay, S.; Groffman, P.; Belt, K.; Delaney, K.; Sides, A.; Walbridge, M.; Mayer, P.

2009-05-01

346

Biological Uptake of Dissolved Silica in the Amazon River Estuary  

Microsoft Academic Search

Approximately 25 percent of the dissolved silica carried by the Amazon River is depleted through diatom production in the inner estuary. Annual production of opaline frustules is estimated to be 15 million tons. However, few diatoms accumulate in modern shelf sediments and chemical recycling appears to be slight. Instead, many frustules apparently are transported landward into the river system, where

John D. Milliman; Edward Boyle

1975-01-01

347

Effects of temperature variation on critical stream dissolved oxygen  

Microsoft Academic Search

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 increasing temperature, tending to raise it. The decay coefficient monotonically increases with increasing temperature, lowering the DO for single discharges but not necessarily

J. Wayland Eheart

1989-01-01

348

Subaquatic oxidation of coal by water-dissolved oxygen  

Microsoft Academic Search

Subaquatic oxidation of two bituminous coals by water-dissolved oxygen was investigated using batch reactor equipped with membrane oxygen sensor. Effects of time, temperature and coal grain size were studied as basic parameters influencing the oxidation process. Obtained results showed the subaquatic coal oxidation can be considered as interaction of the first reaction order with respect to oxygen. From temperature dependence

Boleslav Taraba; Jan Kupka

2010-01-01

349

Effects of temperature variation on critical stream dissolved oxygen  

Microsoft Academic Search

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 increase monotonically with increasing temperature, tending to raise it. The decay coefficient monotonically increases with increasing temperature, lowering the DO for single discharges but not necessarily

J. Wayland Eheart

1989-01-01

350

PHOTOCHEMICAL TRANSFORMATIONS OF DISSOLVED ORGANIC MATTER IN A BLACKWATER RIVER  

EPA Science Inventory

We examined photochemical alterations of dissolved organic matter (DOM) from the Satilla River, a high DOC (10-40 mg/liter) blackwater river of southeast Georgia. Water samples were filtered to remove most organisms, placed in quartz tubes, and incubated under natural sunlight a...

351

Predicting Diel Dissolved Oxygen Dynamics in the Carson River, Nevada  

Microsoft Academic Search

The Carson River originates in eastern Alpine County California, flows northeast into western Nevada through Carson City, and terminates in the Carson Sink. Elevated nutrient levels from agricultural return flows allow for excess attached algal (periphyton) growth. Periods of low flow, coupled with an abundance of periphyton, harbor an environment capable of producing dissolved oxygen concentrations less than 5 mg

Z. B. Latham; J. J. Warwick; C. H. Fritsen

2005-01-01

352

Dissolved oxygen and thermal regimes of a Ugandan crater lake  

Microsoft Academic Search

This paper quantifies the temporal pattern of thermal stratification and deoxygenation in Lake Nkuruba, a small (3 ha), deep (maximum depth = 38 m) crater lake in western Uganda. Dissolved oxygen penetrated to an average depth of 9 m and a maximum depth of 15 m below which the lake was permanently anoxic over the 2 years of study. Although

Lauren J. Chapman; Colin A. Chapman; Thomas L. Crisman; Frank G. Nordlie

1998-01-01

353

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...

354

Effects of hydrodynamically rough grassed waterways on dissolved reactive phosphorus loads coming from agricultural watersheds.  

PubMed

A modified type of grassed waterway (GWW) with large hydrodynamic roughness has proven ability to reduce sediment load and surface runoff under conditions where best management practices on the delivering fields reduce sediment inputs that could otherwise damage the grass cover. It is unknown how such a GWW affects the loading of surface runoff with dissolved reactive phosphorus (DRP). The effect on DRP was tested in a landscape-scale study where DRP concentrations and loads in surface runoff were measured in two watersheds in which GWWs were newly installed and increased in effectiveness over time. Both watersheds were compared with paired watersheds without GWW installation; all watersheds were continuously monitored over 5 yr (1993-1997). Additionally, DRP concentrations were measured in open field and throughfall precipitation under growing grass and crops in field experiments, and DRP concentrations in surface runoff from straw covered surfaces were determined with laboratory rainfall simulation experiments. Dissolved reactive P in throughfall for the different cover types was highly variable, and the highest concentrations (up to 2.8 mg L(-1)) occurred especially during flowering of the respective crop and after frost events. Dissolved reactive P concentrations in runoff from straw-covered surfaces were slightly higher compared with those from bare soil. On average, there was a small difference in DRP concentrations between throughfall under growing crops and grass and in runoff from bare or straw covered soil surfaces. Hence, the introduction of a relatively small grassed area has little effect on the DRP concentration in surface runoff from the total watershed. This finding was supported by the watershed data, where watersheds with and without GWW showed similar DRP concentrations. No change in DRP concentrations occurred over the 5-yr period. Such GWWs will thus reduce the DRP load analogously to the reduction in total surface runoff. PMID:19202025

Fiener, P; Auerswald, K

2009-01-01

355

Effects of photodegradation of dissolved organic matter on the binding of benzo(a)pyrene.  

PubMed

Dissolved organic matter (DOM) in natural waters can bind various organic pollutants, and the affinity of this binding is strongly influenced by the chemical characteristics of the DOM and water pH. This study examined the effects of photochemically induced alteration of the DOM's chemical properties and water pH on the binding of benzo(a)pyrene (BaP). Time- and pH-series of solar-simulated irradiations were performed on a natural water sample and aqueous DOM solutions prepared from aquatic and soil humic substances. The binding affinity of BaP, expressed as a partition coefficient of a compound to DOM, decreased substantially after the DOM samples were irradiated over environmentally relevant radiation doses and pH ranges. The lowering of the pH due to the photoproduction of acidic products often partly offsets the reduction of the binding affinity caused by direct photoalteration of the DOM's chemical structure. The decrease of the binding affinity, after correction for the photoinduced pH change, was positively correlated with the decrease in the molecular weight and the aromaticity of the DOM in the course of irradiation. Increasing O(2) abundance accelerated the decrease of the binding affinity as a result of enhanced DOM photodegradation. Visible light played a more important role in reducing the molecular weight and aromaticity of the DOM than in reducing the content of dissolved organic carbon (DOC) via photoremineralization while the reverse was true for UV radiation, indicating that photochemical reduction of the binding affinity may occur in natural waters at depths greater than UV radiation can reach. A decrease of the affinity of DOM for binding BaP will increase the free dissolved fraction of BaP and thus its availability and toxicity to aquatic organisms. The results from this study may have similar implications for organic pollutants other than BaP. PMID:16406054

Lou, Tao; Xie, Huixiang; Chen, Guohua; Gagné, Jean-Pierre

2006-08-01

356

Modeling the liquid-phase oxidation of hydrocarbons over a range of temperatures and dissolved oxygen concentrations with pseudo-detailed chemical kinetics  

Microsoft Academic Search

The ability of pseudo-detailed chemical kinetic modeling to simulate the oxidation behavior of Exxsol D-80, a paraffin blend whose oxidative characteristics are representative of severely hydrotreated jet fuels, is assessed. The effects of temperature and initial dissolved O2 concentration on oxidation are considered. A 17-step pseudo-detailed mechanism is shown to provide reasonable simulations of Exxsol D-80 oxidation over a range

Nicholas J. Kuprowicz; Jamie S. Ervin; Steven Zabarnick

2004-01-01

357

Dissolved organic carbon and dissolved organic nitrogen export from forested watersheds in Nova Scotia: Identifying controlling factors  

Microsoft Academic Search

Riverine nutrient export represents a transfer of terrestrial nutrients to lakes, estuaries and the near-coastal zone. In this study, we constructed regional predictive models for riverine dissolved organic carbon (DOC) and organic nitrogen (DON) exports. We used a subset of 10 watersheds to construct regional empirical models of DOC and DON export, reserving two watersheds for testing the predictive ability

J. A. Aitkenhead-Peterson; J. E. Alexander; T. A. Clair

2005-01-01

358

Responses of atlantic salmon ( Salmo salar ) alevins to dissolved organic carbon and dissolved aluminum at low pH  

Microsoft Academic Search

Mortality of Atlantic salmon alevins in solutions containing Al and dissolved organic anions (both synthetic and natural) was correlated with Al accumulation in alevin tissues. Both mortality and accumulation could be related to the concentration differences between Al and organic anions. Mortality and body accumulation of Al both increased dramatically as total Al concentrations increasingly exceeded organic anion concentrations. Alevin

R. H. Peterson; R. A. Bourbonnière; G. L. Lacroix; D. J. Martin-Robichaud; P. Takats; G. Brun

1989-01-01

359

Heat as a tracer to estimate dissolved organic carbon flux from a restored wetland.  

PubMed

Heat was used as a natural tracer to characterize shallow ground water flow beneath a complex wetland system. Hydrogeologic data were combined with measured vertical temperature profiles to constrain a series of two-dimensional, transient simulations of ground water flow and heat transport using the model code SUTRA (Voss 1990). The measured seasonal temperature signal reached depths of 2.7 m beneath the pond. Hydraulic conductivity was varied in each of the layers in the model in a systematic manual calibration of the two-dimensional model to obtain the best fit to the measured temperature and hydraulic head. Results of a series of representative best-fit simulations represent a range in hydraulic conductivity values that had the best agreement between simulated and observed temperatures and that resulted in simulated pond seepage values within 1 order of magnitude of pond seepage estimated from the water budget. Resulting estimates of ground water discharge to an adjacent agricultural drainage ditch were used to estimate potential dissolved organic carbon (DOC) loads resulting from the restored wetland. Estimated DOC loads ranged from 45 to 1340 g C/(m2 year), which is higher than estimated DOC loads from surface water. In spite of the complexity in characterizing ground water flow in peat soils, using heat as a tracer provided a constrained estimate of subsurface flow from the pond to the agricultural drainage ditch. PMID:16029180

Burow, Karen R; Constantz, Jim; Fujii, Roger

2005-01-01

360

Heat as a tracer to estimate dissolved organic carbon flux from a restored wetland  

USGS Publications Warehouse

Heat was used as a natural tracer to characterize shallow ground water flow beneath a complex wetland system. Hydrogeologic data were combined with measured vertical temperature profiles to constrain a series of two-dimensional, transient simulations of ground water flow and heat transport using the model code SUTRA (Voss 1990). The measured seasonal temperature signal reached depths of 2.7 m beneath the pond. Hydraulic conductivity was varied in each of the layers in the model in a systematic manual calibration of the two-dimensional model to obtain the best fit to the measured temperature and hydraulic head. Results of a series of representative best-fit simulations represent a range in hydraulic conductivity values that had the best agreement between simulated and observed temperatures and that resulted in simulated pond seepage values within 1 order of magnitude of pond seepage estimated from the water budget. Resulting estimates of ground water discharge to an adjacent agricultural drainage ditch were used to estimate potential dissolved organic carbon (DOC) loads resulting from the restored wetland. Estimated DOC loads ranged from 45 to 1340 g C/(m2 year), which is higher than estimated DOC loads from surface water. In spite of the complexity in characterizing ground water flow in peat soils, using heat as a tracer provided a constrained estimate of subsurface flow from the pond to the agricultural drainage ditch. Copyright ?? 2005 National Ground Water Association.

Burow, K.R.; Constantz, J.; Fujii, R.

2005-01-01

361

Predicting nitrogen and acidity effects on long-term dynamics of dissolved organic matter.  

PubMed

Increases in dissolved organic carbon (DOC) fluxes may relate to changes in sulphur and nitrogen pollution. We integrated existing models of vegetation growth and soil organic matter turnover, acid-base dynamics, and organic matter mobility, to form the 'MADOC' model. After calibrating parameters governing interactions between pH and DOC dissolution using control treatments on two field experiments, MADOC reproduced responses of pH and DOC to additions of acidifying and alkalising solutions. Long-term trends in a range of acid waters were also reproduced. The model suggests that the sustained nature of observed DOC increases can best be explained by a continuously replenishing potentially-dissolved carbon pool, rather than dissolution of a large accumulated store. The simulations informed the development of hypotheses that: DOC increase is related to plant productivity increase as well as to pH change; DOC increases due to nitrogen pollution will become evident, and be sustained, after soil pH has stabilised. PMID:24077255

Rowe, E C; Tipping, E; Posch, M; Oulehle, F; Cooper, D M; Jones, T G; Burden, A; Hall, J; Evans, C D

2014-01-01

362

Dissolved oxygen regulation by logarithmic/antilogarithmic control to improve a wastewater treatment process.  

PubMed

This paper presents the automation of a real activated sludge wastewater treatment plant, which is located at San Antonio Ajijic in Jalisco, Mexico. The main objective is to create an on-line automatic supervision system, and to regulate the dissolved oxygen concentration in order to improve the performances of the process treating municipal wastewater. An approximate mathematical model is determined in order to evaluate via simulations different control strategies: proportional integral (PI), fuzzy PI and PI Logarithm/Antilogarithm (PI L/A). The controlled variable is dissolved oxygen and the control input is the injected oxygen. Based on this evaluation, the PI L/A controller is selected to be implemented in the real process. After that, the implementation, testing and fully operation of the plant automation are described. With this system, the considered wastewater treatment plant save energy and improves the effluent quality; also, the process monitoring is done online and it is easily operated by the plant users. PMID:24617069

Flores, Victor R; Sanchez, Edgar N; Béteau, Jean-François; Hernandez, Salvador Carlos

2013-01-01

363

[Quantitative analysis of transformer oil dissolved gases using FTIR].  

PubMed

For the defects of requiring carrier gas and regular calibration, and low safety using chromatography to on line monitor transformer dissolved gases, it was attempted to establish a dissolved gas analysis system based on Fourier transform infrared spectroscopy. Taking into account the small amount of characteristic gases, many components, detection limit and safety requirements and the difficulty of degasser to put an end to the presence of interference gas, the quantitative analysis model was established based on sparse partial least squares, piecewise section correction and feature variable extraction algorithm using improvement TR regularization. With the characteristic gas of CH4, C2H6, C2H6, and CO2, the results show that using FTIR meets DGA requirements with the spectrum wave number resolution of 1 cm(-1) and optical path of 10 cm. PMID:24369641

Zhao, An-xin; Tang, Xiao-jun; Wang, Er-zhen; Zhang, Zhong-hua; Liu, Jun-hua

2013-09-01

364

Unimodal response of fish yield to dissolved organic carbon.  

PubMed

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

Finstad, Anders G; Helland, Ingeborg P; Ugedal, Ola; Hesthagen, Trygve; Hessen, Dag O

2014-01-01

365

Azomethine H colorimetric method for determining dissolved boron in water  

USGS Publications Warehouse

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.

Spencer, R. R.; Erdmann, D. E.

1979-01-01

366

Nutrient and dissolved oxygen studies at OTEC sites  

SciTech Connect

In order to adequately assess the impact of artificial upwelling and other possible ecological impacts of OTEC operations on the chemistry of the water column at OTEC sites, studies were initiated at several potential sites. At most sites,hydrocasts were taken at approximately noon and midnight to a depth of about 100 m; samples were collected from about 15 depths to be analyzed for nitrates, nitrites, reactive phosphate, silicate and dissolved oxygen. At some sites, samples were analyzed for various other parameters including ammonia, total organic phosphorus and carbonate alkalinity. Preliminary data on nitrates, phosphates, silicates and dissolved oxygen from several potential sites - off Hawaii, Oahu, Peurto Rico, and the Virgin Islands - are presented and compared. Significant differences between nutrient concentrations have been found at the Caribbean and Hawaiian sites. There is also evidence of seasonal variation at the Oahu site. (LEW)

Quinby-Hunt, M.S.; Fanning, K.; Ziemann, D.; Walsh, T.W.; Knauer, G.A.

1981-07-01

367

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.

368

The availability of dissolved organic phosphorus compounds to marine phytoplankton  

NASA Astrophysics Data System (ADS)

The availability of three dissolved organic phosphorus (DOP) compounds as nutrient sources for experimental culture of three algae was studied. Results indicated that these compounds could be utilized by algae, and that dissolved inorganic phosphorus (DIP) was first to be uptaken when various forms of phosphorus (DIP and DOP) co-existed. Dicrateria zhanjiangensis' uptake of sodium glycerophosphate was faster than that of D-ribose-5-phosphate. The increase of sodium glycerophosphate had little effect on the maximum uptake rate( V max) of Chlorella sp., but increased the semisaturation constant( K s) remarkably; the photosynthesis rates(PR) of Dicrateria zhanjiangensis and Chlorella sp. were rarely affected by using various forms of phosphorus in the culture experiments. The possible DOP pathways utilized by algae are discussed.

Hua-Sheng, Hong; Hai-Li, Wang; Bang-Qin, Huang

1995-06-01

369

Determination of total dissolved solids in water analysis  

USGS Publications Warehouse

The figure for total dissolved solids, based on the weight of the residue on evaporation after heating for 1 hour at 180??C., is reasonably close to the sum of the determined constituents for most natural waters. Waters of the carbonate type that are high in magnesium may give residues that weigh less than the sum. Natural waters of the sulfate type usually give residues that are too high on account of incomplete drying.

Howard, C. S.

1933-01-01

370

Dissolved gaseous mercury behavior in shallow water estuaries  

E-print Network

of dissolved gaseous mercury (DGM) can be an important pathway for mercury removal from an aquatic environment. DGM evasional fluxes from an aquatic system can account for up to 95% of atmospheric Hg and its deposition pathways. While this makes DGM... to or below zero after sunset. This study does contribute to the understanding of DGM cycling in aquatic environments as there are few studies that have made continuous DGM measurements in estuarine environments. v DEDICATION To my parents...

Landin, Charles Melchor

2008-10-10

371

Subtidal Variability of Dissolved Oxygen in Western Long Island Sound  

Microsoft Academic Search

A simple model of the subtidal budget of dissolved oxygen in estuaries is developed and applied to observations in western Long Island Sound. The goal is to analyze the causes of hypoxia and develop a predictive capability for its onset and duration by estimating mixing coefficients and comparing simple models of their temporal variability. A single-segment lower-layer box-model for western

P. S. Gay; J. O'Donnell

2008-01-01

372

Continuous monitoring of short term dissolved oxygen and algal dynamics  

Microsoft Academic Search

Dissolved oxygen (DO) in coastal bays with frequent algal blooms can undergo significant diurnal changes. Short-term DO and algal dynamics in a sub-tropical, nitrogen-limited, marine ecosystem are studied by means of a specially designed telemetry system. The high resolution data show clearly the importance of the vertical DO structure, and its relationship with environmental variables (solar radiation, water temperature, wind,

H. S. Lee; Joseph H. W. Lee

1995-01-01

373

Flocculation and Air Requirements for Dissolved Air Flotation  

Microsoft Academic Search

Bench-scale and pilot-plant studies were used to investigate the effects of flocculation time and floe size on the performance of dissolved air flotation and to determine air requirements for three different types of water supplies. The results show that long flocculation periods are not needed and suggest that floc particles of 10-30 ?m should be prepared for flotation. Two measures

James K. Edzwald; John P. Walsh; Gary S. Kaminski; Howard J. Dunn

1992-01-01

374

Microfabirated Clark-type Sensor for Measuing Dissolved Oxygen  

Microsoft Academic Search

This paper presents a microfabricated Clark-type sensor which exactly can measure dissolved oxygen in the cell containing solution. We designed and fabricated a microfabricated Clark-type sensor for measuring the oxygen respiration level of few cells. The microfabricated Clark-type sensor is composed of 3-electrodes on a glass substrate, a FEP (Fluorinated ethylene propylene) oxygen-permeable membrane, and PDMS (Polydimethylsiloxane) reservoir for storing

Jong-hyeon Chang; Myungki Choi; J. J. Pak; Dong-Young Lee; Youngmi Kim Pak

2007-01-01

375

Characterization of ormosil film for dissolved oxygen-sensing  

Microsoft Academic Search

An organically modified silicate (ormosil) as a matrix for the fabrication of dissolved oxygen-sensing film was produced. The process included taking tetramethoxysilane (TMOS) and dimethyldimethoxysilane (DiMe-DMOS) as precursor and running a reaction at 60°C in an open vial, which accelerates hydrolysis and condensation and results in the formation of emulsion. The film doped with tris-(4,7-diphenyl-1,10-phenanthroline) ruthenium(II) ([Ru(dpp)3]2+) as an oxygen

Xi Chen; Zhenming Zhong; Zhen Li; Yaqi Jiang; Xiaoru Wang; Kwokyin Wong

2002-01-01

376

ORMOSIL oxygen sensors on polystyrene microplate for dissolved oxygen measurement  

Microsoft Academic Search

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

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

2007-01-01

377

Wind Modulation of Dissolved Oxygen in Chesapeake Bay  

Microsoft Academic Search

A numerical circulation model with a simplified dissolved oxygen module is used to examine the importance of wind-driven ventilation\\u000a of hypoxic waters in Chesapeake Bay. The model demonstrates that the interaction between wind-driven lateral circulation and\\u000a enhanced vertical mixing over shoal regions is the dominant mechanism for providing oxygen to hypoxic sub-pycnocline waters.\\u000a The effectiveness of this mechanism is strongly

Malcolm E. Scully

2010-01-01

378

Membrane Inlet Mass Spectrometry for measuring dissolved gases  

SciTech Connect

A Membrane Inlet Mass Spectrometer (MIMS) is used to measure dissolved gas concentrations in environmental water samples. Gases are exsolved out of water by passing the sample through a silicone gas permeable membrane that is under vacuum. A quadrupole mass spectrometer attached to the vacuum system is capable of measuring a variety of gases over a wide range of concentration. The MIMS is a versatile and field portable instrument.

Singleton, M; Hudson, G

2005-08-10

379

Predicting dissolved oxygen in the Chesapeake Bay: applications and implications  

Microsoft Academic Search

Eutrophic depletion of dissolved oxygen (DO) and its consequences for ecosystem dynamics have been a central theme of research,\\u000a assessment and management policies for several decades in the Chesapeake Bay. Ongoing forecast efforts predict the extent\\u000a of the summer hypoxic\\/anoxic area due to nutrient loads from the watershed. However, these models neither predict DO levels\\u000a nor address the intricate interactions

M. Bala Krishna Prasad; Wen Long; Xinsheng Zhang; Robert J. Wood; Raghu Murtugudde

380

Spontaneous assembly of marine dissolved organic matter into polymer gels  

Microsoft Academic Search

A large pool of organic carbon resides in the world's oceans in the form of dissolved organic matter (DOM),. DOM is operationally defined as the fraction of organic matter that passes through a filter with a given pore size (which can range from less than 0.1mum to 0.46mum). This fraction has a longer oceanic residence time - and is generally

Wei-Chun Chin; Mónica V. Orellana; Pedro Verdugo

1998-01-01

381

Method of removing dissolved non-condensibles from geothermal brines  

Microsoft Academic Search

Heat energy is more efficiently recovered from geothermal brines by preflashing the brine to remove dissolved, non-condensible gases before flashing the brine to produce motive steam. Power requirements for removal of non-condensibles from turbine exhausts (in order to maintain adequately low exhaust pressures) are obviated. The heat content of the pre-flashed vapors may be largely utilized for superheating and reheating

1977-01-01

382

Binding of inorganic phosphate to dissolved metal humates  

Microsoft Academic Search

A cobalt-wire electrode was used to determine the concentration of free phosphate (P) in solutions containing a series of metal humates (MHA). The results were used in Scatchard plots to determine the stability constants of the dissolved MHA–P complexes formed. The constants were found to be high, with logK values in the range 4.8–6.0. Solutions containing MHA–P complexes were found

Jeremy Riggle; Ray von Wandruszka

2005-01-01

383

Dissolved oxygen imaging to investigate biodegradation at lab scale  

Microsoft Academic Search

A novel combination of a non-invasive imaging method with an oxygen sensitive fluorescent indicator was developed to investigate the biodegradation processes occurring at the fringe of a solute plume. A thin transparent porous matrix was made from quartz plates and quartz sand and acetate was continuously injected in the uniform flow field containing dissolved oxygen. Ruthenium (II)-dichlorotris(1,10-phenanthroline) (Ru(phen)3Cl2), a water

D. N. Lerner; H. Rees; W. E. Huang; C. C. Smith; S. E. Oswald

2003-01-01

384

Geochemistry and Reactivity of Exported Congo Riverine Dissolved Organic Matter  

Microsoft Academic Search

The Congo River basin drains the second largest area of rainforest in the world and is also the second largest river in terms of catchment size (3,680,000 km2) and freshwater discharge (42,000 m3 s- 1). Congo riverine dissolved organic carbon (DOC) export is estimated at 12.4 Tg DOC yr -1 or approximately 5 % of global riverine DOC export to

R. G. Spencer; A. P. Stubbins; P. J. Hernes; A. K. Aufdenkampe; P. Gulliver; K. Mopper; A. Baker; R. Y. Dyda; J. W. Six

2008-01-01

385

A flow system for calibration of dissolved oxygen sensors  

Microsoft Academic Search

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

P. Jeroschewski; D. zur Linden

1997-01-01

386

Variability in dissolved oxygen off Eastern Luzon, Philippines  

NASA Astrophysics Data System (ADS)

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.

San Diego-McGlone, M.; Escobar, M.; Jacinto, G.; Villanoy, C. L.

2013-12-01

387

A hand-held optical sensor for dissolved oxygen measurement  

NASA Astrophysics Data System (ADS)

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 was captured by a silicon photodiode. The long-pass filter efficiently reduced the scattered light from the light source. The emission signal of the optode membrane was converted to the voltage signal which was processed by a single-chip Micyoco controller, and the dissolved oxygen concentration was automatically displayed on a liquid crystal display unit. The developed hand-held optical sensor is a single-piece device which can provide instant and reliable dissolved oxygen measurement. The sensor showed good repeatability, photostability and long-term stability. Satisfactory results were obtained when its analytical performance was compared with that of a typical Clark-type amperometric oxygen electrode. The developed oxygen optical sensor possesses the advantages of portability, low cost and long lifetime.

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

2003-06-01

388

Sequestration of Dissolved CO2 in the Oriskany Formation  

SciTech Connect

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.

Dilmore, R.M.; Allen, D.E. (Salem State College, Salem, MA); McCarthy-Jones, J.R.; Hedges, S.W.; Soong, Yee

2008-04-15

389

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...

390

THE ROLE OF NITROGEN IN CHROMOPHORIC AND FLUORESCENT DISSOLVED ORGANIC MATTER FORMATION  

EPA Science Inventory

Microbial and photochemical processes affect chromophoric dissolved organic matter (CDOM) dynamics in the ocean. Some evidence suggests that dissolved nitrogen plays a role in CDOM formation, although this has received little systematic attention in marine ecosystems. Coastal sea...

391

Dissolved cadmium in the Southern Ocean: Distribution, speciation, and relation to phosphate  

E-print Network

Dissolved cadmium in the Southern Ocean: Distribution, speciation, and relation to phosphate Oliver dilution analyses of dissolved cadmium (Cd) and electrochemical Cd speciation mea- surements : P uptake ratios in the trace-nutrient�limited Southern Ocean. Oceanic cadmium and phosphate

Boyer, Edmond

392

Rapid extraction of dissolved inorganic carbon from seawater and groundwater samples for radiocarbon dating  

E-print Network

The focus of this thesis is the design and development of a system for rapid extraction of dissolved inorganic carbon from seawater and groundwater samples for radiocarbon dating. The Rapid Extraction of Dissolved Inorganic ...

Gospodinova, Kalina Doneva

2012-01-01

393

Characterizing the Dissolved Nitrogen Retention Dynamics in Hillslopes and River Networks across a Climate Gradient  

NASA Astrophysics Data System (ADS)

Dissolved nitrogen is delivered from hillslopes to oceans via river networks, and during the transport process, some can be retained in the hillslope and river networks temporarily or removed permanently (i.e. by plant assimilation or microbial denitrification). Recent research shows that watershed characteristics, land use and land cover, ecosystem type, etc., strongly control the amount of nitrogen released to river networks. On the other hand, based on previous theoretical analyses, we have found that bulk nitrogen retention in river networks can be different across the climate gradient as well across spatial scale (e.g., between headwater streams and higher order streams). Climate, in combination with landscape factors, determines the statistical distribution of within-year variability of streamflow (e.g., frequency and duration of high and low flows), and thus has a significant impact on intra-annual variability on nitrogen retention rates at all scales: the more variable the streamflow, the greater the nitrogen export. We use a model with three pools for the dynamics of inorganic nitrogen in the soil, to simulate the nitrogen retention dynamics in the hillslope; and a dynamic hydrologic network model, coupled with a transient storage zone solute transport model to simulate dissolved nitrogen retention processes during transient flow events in the channel network. The model was applied to a 500 km2 typical watershed in Illinois, and twelve different climates (e.g., dry and humid, warm and cold) from MOPEX sites were explored to understand how climate impacts on the amount of nitrogen that is retained in terrestrial landscape and in the river network, and the separate contributions to nitrogen retention by the hillslope and by the stream network. Preliminary results indicate that the retention rate varies with dominant climate factors (e.g., rainfall driven, snowmelt dominant, etc.); besides, climate variability also has a significant impact on the nitrogen retention rate in both hillslopes and channels: the higher the rainfall variability, the smaller the nitrogen retained.

Ye, S.; Sivapalan, M.; Quijano, J. C.; Yaeger, M. A.

2011-12-01

394

Variable C : N : P stoichiometry of dissolved organic matter cycling in the Community Earth System Model  

NASA Astrophysics Data System (ADS)

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 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 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.

Letscher, R. T.; Moore, J. K.; Teng, Y.-C.; Primeau, F.

2014-06-01

395

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

NASA Astrophysics Data System (ADS)

Fiber optic chemical sensors (FOCS) for oxygen, dissolved oxygen (DO), and dissolved CO2 sensing using thin films of fluorophores encapsulated in sol-gel matrices were made and tested. The DO/O2 sensor used ruthenium(II) tris(4,7-diphenyl-1,10-phenanthroline) perchlorate (Ru(Ph 2Phen)Cl2) as the oxygen sensitive fluorophore and methyltrimethoxysilane (MTMS) sol-gel as the encapsulating matrix material. For the DCO2 sensor, 8-hydroxy-1,3,6-pyrenetrisulfonic acid trisodium salt (HPTS) co-doped with sodium bicarbonate was used as the DCO2 sensitive fluorophore-chemical system and diisobutoxy-alumino triethoxysilane (ASE) sol-gel was used as the encapsulating matrix material. It was found that oxygen quenches the excited state Ru(Ph2Phen)Cl 2 by diffusing through the MTMS matrix. Continuous excitation of Ru(Ph 2Phen)Cl2 during MTMS drying resulted in long, single exponential lifetimes of the metal complex and increased sensor sensitivity. When the sensor was field tested, it was found to have an excellent match compared to conventional titration method for determining dissolved oxygen concentrations and had fast response times. It was determined that this sensor measured the vapor pressure of oxygen rather than the absolute concentration of dissolved oxygen. For DCO2 sensing, it was found that the dynamic response of the senor could be tuned by varying the HPTS to NaHCO3 ratios. The sensor had fast response times compared to other fiber optic DCO 2 sensors reported which typically have response times of minutes.

Kwon, Hyeog-Chan

396

Improved Equipment for Sampling Dissolved Oxygen at Levee-Pond Commercial Aquaculture Facilities  

Microsoft Academic Search

An inexpensive modification for off-road vehicles provides a simple technique for deploying dissolved oxygen meter probes without leaving the vehicle or opening the window. The equipment, specifically developed and tested for nighttime dissolved oxygen monitoring at commercial catfish farms, increases efficiency in collecting large numbers of dissolved oxygen samples at aquaculture facilities or fish hatcheries where dikes enable vehicular access.

Danilo Zamora; Michael D. Porter

2000-01-01

397

Behavioral response of fish larvae to low dissolved oxygen concentrations in a stratified water column  

Microsoft Academic Search

Density stratification and respiration lead to vertical gradients in dissolved oxygen in many aquatic habitats. The behavioral responses of fish larvae to low dissolved oxygen in a stratified water column were examined during 1990–1991 with the goal of understanding how vertical gradients in dissolved oxygen may directly affect the distribution and survival of fish larvae in Chesapeake Bay, USA. In

D. L. Breitburg

1994-01-01

398

Electrocatalytic removal of dissolved oxygen from seawater in a packed-bed electrode  

Microsoft Academic Search

Oxygen dissolved in seawater is the source of severe corrosion issues in off-shore platforms for oil exploitation. The electrocatalytic reduction of dissolved oxygen from seawater was investigated at laboratory scale as an alternative to the current processes for the removal of oxygen. Due to the low concentration of dissolved oxygen and the very high conversion required before use of seawater

P. Kinzel; H. G. Lintz; P. Gaudebert; G. Bousquet; F. Lapicque; G. Valentin

2002-01-01

399

NOTES ON THE DISSOLVED CONTENT OF WATER IN ITS EFFECT UPON FISHES  

E-print Network

. That air dissolved in the water is necessary to support fishes is a matter of com- mon knowledge to conclude from this that foreign matter other than dissolved air. is a necessary accompaniment of water.. NOTES ON THE DISSOLVED CONTENT OF WATER IN ITS EFFECT UPON FISHES· JJ. By M. C. Marsh United

400

Deep-Sea Research I 54 (2007) 710731 Hydrography of chromophoric dissolved organic matter  

E-print Network

The chromophoric fraction of dissolved organic matter (CDOM) is ubiquitous in all natural waters ARTICLE IN PRESSDeep-Sea Research I 54 (2007) 710­731 Hydrography of chromophoric dissolved organic matter of chromophoric dissolved organic matter (CDOM) were systematically investigated along three meridional transects

California at Santa Barbara, University of

401

Contribution of amino compounds to dissolved organic nitrogen in forest soils  

E-print Network

Contribution of amino compounds to dissolved organic nitrogen in forest soils Z. YU, Q. ZHANG, T 2001 Key words: Amino acids, Dissolved organic nitrogen, Nitrogen, Nutrient cycling, Polyphenols, Pro- teins Abstract. Dissolved organic nitrogen (DON) may play an important role in plant nutrition

Zhang, Qi

402

Extractable and dissolved soil organic nitrogen A quantitative assessment Gerard H. Ros a,*, Ellis Hoffland a  

E-print Network

Review Extractable and dissolved soil organic nitrogen � A quantitative assessment Gerard H. Ros a of Soil Quality, P.O. Box 47, 6700 AA Wageningen, The Netherlands b University of California, Department: Dissolved Organic Nitrogen (DON) Soluble Organic Nitrogen (SON) Dissolved Organic Matter (DOM) Methodology

van Kessel, Chris

403

UTILIZATION OF DISSOLVED NITROGEN BY HETEROTROPHIC BACTERIOPLANKTON: EFFECT OF SUBSTRATE C/N RATIO  

EPA Science Inventory

The significance of dissolved combined amino acids (DCAA), dissolved free amino acids (DFAA), and dissolved DNA (D-DNA) as sources of C and N for marine bacteria in batch cultures with variable substrate C/N ratios was studied. lucose, ammonium, alanine, and phosphate were added ...

404

In-situ measurement of dissolved nitrogen and oxygen in the ocean  

Microsoft Academic Search

Motivated by the need to separate changes in dissolved gas concentrations due to air-sea fluxes from biological production, a novel method of inferring dissolved nitrogen in the ocean is described. The method requires a local measurement of gas tension, dissolved oxygen, water temperature and salinity. Such instrumentation has been developed and tested at sea. Preliminary open ocean data are presented.

Craig L. McNeil; Bruce D. Johnson; David M. Farmer

1995-01-01

405

Continuous measurements of dissolved oxygen isotopes in the California coastal ocean  

Microsoft Academic Search

The triple isotopic composition of dissolved oxygen can be used to measure oceanic primary production. Previous studies have determined the triple isotopic composition of dissolved oxygen using flask samples of water, where dissolved gases are equilibrated with the flask headspace and analyzed on a mass spectrometer. We present results from a 2009 cruise in the coastal Pacific Ocean off Southern

L. E. Rafelski; R. F. Keeling; B. Paplawsky; A. C. Cox

2010-01-01

406

UNIVERSITY OF CALIFORNIA, SAN DIEGO Continuous surface ocean measurements of dissolved oxygen isotopes  

E-print Network

UNIVERSITY OF CALIFORNIA, SAN DIEGO Continuous surface ocean measurements of dissolved oxygen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Chapter 2 An equilibrator to measure dissolved oxygen and its isotopes . 14 2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 v #12;Chapter 3 Mass spectrometer methods for measuring dissolved oxygen isotopes

Keeling, Ralph

407

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

E-print Network

Dissolved oxygen stratification in two micro-tidal partially-mixed estuaries Jing Lin a,*, Lian Xie that vertical stratification of dissolved oxygen (DO) concentration can be explained by the extended Hansen reserved. Keywords: dissolved oxygen; stratification; estuarine gravitational circulation; vertical mixing

Mallin, Michael

408

Elevated Fe(II) and Dissolved Fe in Hypoxic Shelf Waters off Oregon  

E-print Network

results in subsurface water depleted in dissolved oxygen over the mid and inner shelf as low oxygen water(BBL).Additionalrespiration of the high export production from the overlying productive waters can decrease dissolved oxygen even further by several variables. Model equilibrium calculations indicate that in oxygenated seawater dissolved Fe exists

Hickey, Barbara

409

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

E-print Network

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

Papautsky, Ian

410

Effects of applied voltages and dissolved oxygen on sustained power generation by microbial fuel cells  

E-print Network

Effects of applied voltages and dissolved oxygen on sustained power generation by microbial fuel chamber MFCs at the end of a cycle when the substrate is depleted. A slight increase in dissolved oxygen chamber for sustained performance of MFCs. Key words | anode, applied voltage, dissolved oxygen, microbial

411

Interspecific variation in gill size is correlated to ambient dissolved oxygen in the Amazonian electric fish  

E-print Network

Interspecific variation in gill size is correlated to ambient dissolved oxygen in the Amazonian Introduction The availability of dissolved oxygen (DO) can influence the distribution and movement of fishes.V. 2007 Abstract Gymnotiform electric fish assemblage struc- ture is strongly correlated to dissolved

Chapman, Lauren J.

412

Control and effect of dissolved air in water during flow boiling in microchannels  

E-print Network

for the dissolved oxygen content of 8.0 parts per million (ppm) at a pressure of 1 atm with untreated de-ionized water. For the dissolved oxygen contents of 5.4 and 1.8 ppm, nucleation is not observed untilControl and effect of dissolved air in water during flow boiling in microchannels Mark E. Steinke

Kandlikar, Satish

413

Stream Monitoring 1. Students learn how researchers test three stream parameters: temperature, dissolved  

E-print Network

: temperature, dissolved oxygen and pH. 2. Formulate a hypothesis and test it. Background Water quality flow, dissolved oxygen, temperature, pH, conductivity, nitrogen, phosphorus, total solids, turbidity, and fecal bacteria. Note: in this activity we are only measuring temperature, pH and dissolved oxygen

Schladow, S. Geoffrey

414

NOAA Technical Memorandum ERL.GLERL-21 TEMPERATURE AND DISSOLVED OXYGEN DATA  

E-print Network

NOAA Technical Memorandum ERL.GLERL-21 TEMPERATURE AND DISSOLVED OXYGEN DATA FOR LAKE ONTARIO, 1972. REFERENCES Appendix'A. STATISTIC& SUMMARY BY CRUISE OF THE TEMPERATURE, DISSOLVED OXYGEN, AND PERCENT SATURATION DATA Appendix B. TEMPERATURE, DISSOLVED OXYGEN, AND PERCENT SATURATION DATA FOR ALL AVAILABLE

415

The dual influences of dissolved organic carbon on hypolimnetic metabolism: organic substrate and  

E-print Network

by the depth and magnitude of the deep dissolved oxygen maxima) in the high DOC lakes. In June, the hypolimnia of lakes with dissolved oxygen and no CH4, whileThe dual influences of dissolved organic carbon on hypolimnetic metabolism: organic substrate

Pace, Michael L.

416

Development of a dissolved oxygen sensor using tris(bipyridyl) ruthenium (II) complexes entrapped  

E-print Network

Development of a dissolved oxygen sensor using tris(bipyridyl) ruthenium (II) complexes entrapped-exchange sites in the siliceous zeolites. The emission quenching of intrazeolitic Ru(bpy)2þ 3 by oxygen dissolved prepared and examined as sensors for dissolved oxygen. � 2003 Elsevier Inc. All rights reserved. Keywords

Dutta, Prabir K.

417

Abstract Low dissolved oxygen concentrations present numerous challenges for non-air-breathing aquatic or-  

E-print Network

Abstract Low dissolved oxygen concentrations present numerous challenges for non- pact of dissolved oxygen on predator-prey interactions, and suggest that outcomes depend on the respiratory ecology of both predator and prey. Key words Air-breathing · Rana catesbeiana · Dissolved oxygen

McIntyre, Peter

418

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

E-print Network

Relationships among Nutrients, Chlorophyll-a, and Dissolved Oxygen in Agricultural Streams understanding of the controls on algae and dissolved O2 in agricultural streams of Illinois is needed to aid abundance, and dissolved O2 in five streams in east-central Illinois from March through November 2004

David, Mark B.

419

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

E-print Network

, Washington Prepared in cooperation with the Hood Canal Dissolved Oxygen Program Scientific Investigations, and Theresa D. Olsen Prepared in cooperation with the Hood Canal Dissolved Oxygen Program ScientificFreshwater and Saline Loads of Dissolved Inorganic Nitrogen to Hood Canal and Lynch Cove

420

Observed Evolution of Vertical Profiles of Stratification and Dissolved Oxygen in Long Island Sound  

E-print Network

Observed Evolution of Vertical Profiles of Stratification and Dissolved Oxygen in Long Island Sound University of New York, Stony Brook Motivation Levels of dissolved oxygen below the 3 mg/l threshold stratification, and changes in dissolved oxygen concentrations, based on direct observations. The suite

Codiga, Daniel L.

421

Dissolved Oxygen Sensing in a Flow Stream using Molybdenum Chloride Optical Indicators  

E-print Network

Dissolved Oxygen Sensing in a Flow Stream using Molybdenum Chloride Optical Indicators Reza Loloee1@msu.edu Abstract--Dissolved oxygen concentration is considered the most important water quality variable in fish culture. Reliable and continuous (24/7) oxygen monitoring of dissolved oxygen (DO) in the 1 ­ 11 mg

Ghosh, Ruby N.

422

Biochemical Oxygen Demand and Dissolved Oxygen. Training Module 5.105.2.77.  

ERIC Educational Resources Information Center

This document is an instructional module package prepared in objective form for use by an instructor familiar with the azide modification of the Winkler dissolved oxygen test and the electronic dissolved oxygen meter test procedures for determining the dissolved oxygen and the biochemical oxygen demand of a wastewater sample. Included are…

Kirkwood Community Coll., Cedar Rapids, IA.

423

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

Microsoft Academic Search

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.

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

2004-01-01

424

Spatial distribution of dissolved Pb, Hg, Cd, Cu and As in the Bohai Sea  

Microsoft Academic Search

Characteristics of the spatial distribution of selected dissolved heavy metals were analyzed during large scale surveys from August 12 to 25, 2003 in the Bohai Sea. Dissolved Pb was the only element with average concentrations higher than the grade-one sea water quality standard of China. The spatial distribution of dissolved Pb in surface water was similar to those of Cd,

Chang-you WANG; Xiu-lin WANG

2007-01-01

425

Dissolved trace elements in the Mississippi River: Seasonal, interannual, and decadal variability  

Microsoft Academic Search

A monthly trace element sampling of the lower Mississippi River, utilizing ultra-clean methods, was conducted from October 1991 to December 1993. Dissolved concentrations were determined for Fe, Mn, Zn, Ph, V, Mo, U, Cu, Ni, Cd, Rb, and Ba. The results show significant seasonal dissolved concentration changes for a number of elements. Specifically, dissolved Mn and Fe are found to

Alan M. Shiller

1997-01-01

426

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

NASA Astrophysics Data System (ADS)

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.

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

427

Fluxes of Dissolved Trace Metals Evaluated Using Paired Thorium Isotopes  

NASA Astrophysics Data System (ADS)

This study examines the distribution of the long-lived thorium isotopes 232Th and 230Th in the Atlantic Ocean. 232Th in the ocean is derived from the partial dissolution of lithogenic minerals. 230Th is produced at a predictable rate by the decay of uranium, and its subsequent removal by efficient reversible scavenging onto settling particles provides a method to quantify 232Th fluxes to the ocean, and eventually to the seafloor. As such, combining analysis of these two isotopes in seawater has the potential to improve our ability to calculate present and past detrital fluxes to the ocean. Challenges to using this approach are both analytical, for example 232Th contamination issues encountered by many labs during the international GEOTRACES intercalibration, and the lack of systematically collected sample sets. The GEOTRACES program is helping to overcome these issues, giving deeper insights into the processes controlling the sources, sinks and cycling of thorium isotopes in the ocean. In this study, dissolved 232Th was measured in the subtropical North Atlantic, in a region of high Saharan aerosol flux, along the U.S. GEOTRACES section occupied in 2010 and 2011. The section ran from Portugal to Mauritania, under the plume of Saharan dust, and from there via Bermuda to Woods Hole. High concentration of dissolved 232Th were observed in the upper parts of the stations closest to Saharan dust plume as expected for an aerosol supply of lithogenic material to the ocean. However, high dissolved 232Th concentrations were also observed on the western side of the Atlantic basin away from the direct effects of the dust plume indicative of additional surface water lithogenic input sources. Assumptions and prospects for future development will be discussed.

Robinson, L. F.; Huang, K.; Anderson, R. F.; Fleisher, M. Q.; Edwards, R.; Cheng, H.; Moran, S.

2012-12-01

428

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.

429

Toxicity of dissolved ozone to fish eggs and larvae  

SciTech Connect

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.

Asbury, C.; Coler, R.

1980-07-01

430

Bead and Process for Removing Dissolved Metal Contaminants  

SciTech Connect

A bead is provided which comprises or consists essentially of activated carbon immobilized by crosslinked poly (carboxylic acid) binder, sodium silicate binder, or polyamine binder. The bead is effective to remove metal and other ionic contaminants from dilute aqueous solutions. A method of making metal-ion sorbing beads is provided, comprising combining activated carbon, and binder solution (preferably in a pin mixer where it is whipped), forming wet beads, and heating and drying the beads. The binder solution is preferably poly(acrylic acid) and glycerol dissolved in water and the wet beads formed from such binder solution are preferably heated and crosslinked in a convection oven.

Summers, Bobby L., Jr.; Bennett, Karen L.; Foster, Scott A.

2005-01-18

431

In vitro determination of aceclofenac Mouth Dissolving Tablets.  

PubMed

In the present study, Mouth Dissolving Tablets (MDTs) of aceclofenac were formulated by direct compression technique. Sodium starch glycolate and crospovidone were employed as superdisintegrants in various concentrations like 2%, 3% and 4% w/w. All prepared tablets were evaluated for weight variation, hardness, drug content, friability, disintegration time, in vitro wetting time and percent drug release. MDTs containing 4% w/w concentration of crospovidone give best results and is therefore considered as the best formula. It has shown 30 s disintegration time, 25 s wetting time and 79.34% in vitro release of drug in 25 min. PMID:24596037

Shobhit, Shobhit; Gupta, Satish Kumar

2013-01-01

432

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...

433

Bioavailability of dissolved organic nitrogen in treated effluents.  

PubMed

The research objective was to assess dissolved organic nitrogen (DON) bioavailability in wastewater effluents from a pilot-scale nitrification plant and a laboratory-scale total nitrogen (TN) removal plant. The DON bioavailability was assessed using a 14-day bioassay protocol containing bacterial and algal inocula. Nitrogen species, dissolved organic carbon, chlorophyll a, and biomass (as total suspended solids and culturable cell counts) concentrations were measured to assess DON bioavailability. The results showed an increase in algal chlorophyll a concentration, with a concurrent increase in algal biomass over time; increased bacterial counts and a decrease in DON concentration over time; and increased carbon-to-nitrogen ratio at the end of the 14-day bioassay, indicating effluent DON bioavailability to algae and bacteria. Approximately 18 to 61% of the initial DON in low-total-nitrogen wastewater effluent (TN = 4 to 5 mg/L) sample was bioavailable. The results show that bacteria and algae uptake and release DON during their growth. PMID:18605379

Urgun-Demirtas, Meltem; Sattayatewa, Chakkrid; Pagilla, Krishna R

2008-05-01

434

The effects of dissolved gas supersaturation on white sturgeon larvae  

USGS Publications Warehouse

Spill at dams has caused supersaturation of atmospheric gas in waters of the Columbia and Snake rivers and raised concerns about the effects of dissolved gas supersaturation (DGS) on white sturgeons Acipenser transmontanus. The timing and location of white sturgeon spawning and the dispersal of white sturgeon larvae from incubation areas makes the larval stage potentially vulnerable to the effects of DGS. To assess the effects of DGS on white sturgeon larvae, we exposed larvae to mean total dissolved gas (TDG) levels of 118% and 131% saturation in laboratory bioassay tests. Gas bubble trauma (GBT) was manifested as a gas bubble in the buccal cavity, nares, or both and it first occurred at developmental stages characterized by the formation of the mouth and gills. Exposure times of 15 min were sufficient to elicit these signs in larvae in various stages of development. No mortality was observed in larvae exposed to 118% TDG for 10 d, but 50% mortality occurred after a 13-d exposure to 131% TDG. The signs of GBT we observed resulted in positive buoyancy and alterations in behavior that may affect the dispersal and predation vulnerability of white sturgeon larvae. The exact depth distribution of dispersing white sturgeon larvae in the Columbia River currently is unknown. Thus, our results may represent a worst-case scenario if white sturgeon larvae are dispersed at depths with insufficient hydrostatic pressure to compensate for high TDG levels.

Counihan, T. D.; Miller, A. I.; Mesa, M. G.; Parsley, M. J.

1998-01-01

435

Carbon isotopic characterisation of dissolved organic matter during water treatment.  

PubMed

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

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

2014-01-01

436

Nicotine fast dissolving films made of maltodextrins: a feasibility study.  

PubMed

This work aimed to develop a fast-dissolving film made of low dextrose equivalent maltodextrins (MDX) containing nicotine hydrogen tartrate salt (NHT). Particular attention was given to the selection of the suitable taste-masking agent (TMA) and the characterisation of the ductility and flexibility under different mechanical stresses. MDX with two different dextrose equivalents (DEs), namely DE 6 and DE 12, were selected in order to evaluate the effect of polymer molecular weight on film tensile properties. The bitterness and astringency intensity of NHT and the suppression effect of several TMA were evaluated by a Taste-Sensing System. The films were characterised in term of NHT content, tensile properties, disintegration time and drug dissolution test. As expected, placebo films made of MDX DE 6 appeared stiffer and less ductile than film prepared using MDX DE 12. The films disintegrated within 10 s. Among the tested TMA, the milk and mint flavours resulted particularly suitable to mask the taste of NHT. The addition of NHT and taste-masking agents affected film tensile properties; however, the effect of the addition of these components can be counterweighted by modulating the glycerine content and/or the MDX molecular weight. The feasibility of NHT loaded fast-dissolving films was demonstrated. PMID:20936440

Cilurzo, Francesco; Cupone, Irma E; Minghetti, Paola; Buratti, Susanna; Selmin, Francesca; Gennari, Chiara G M; Montanari, Luisa

2010-12-01

437

Measuring and understanding total dissolved gas pressure in groundwater  

NASA Astrophysics Data System (ADS)

Since dissolved gases are important to a number of aspects of groundwater (e.g. age dating, active or passive bioremediation, greenhouse gas fluxes, understanding biogeochemical processes involving gases, assessing potential impacts of coal bed methane activities), accurate concentration measurements, and understanding of their subsurface behaviour are important. Researchers have recently begun using total dissolved gas pressure (TGP) sensor measurements, more commonly applied for surface water monitoring, in concert with gas composition analyses to estimate more accurate groundwater gas concentrations in wells. We have used hydraulic packers to isolate the well screens where TDP is being measured, and pump tests to indicate that in-well degassing may reduce TDG below background groundwater levels. Thus, in gas-charged groundwater zones, TGPs can be considerably underestimated in the absence of pumping or screen isolation. We have also observed transient decreased TGPs during pumping that are thought to result from ebullition induced when the water table or water level in the well is lowered below a critical hydrostatic pressure.

Ryan, C.; Roy, J. W.; Randell, J.; Castellon, L.

2009-05-01

438

Cracking of duplex stainless steel due to dissolved hydrogen  

SciTech Connect

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).

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

439

Production of Dissolved Organic Matter During Fungal Wood Rot Decay  

NASA Astrophysics Data System (ADS)

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

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

2002-12-01

440

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

SciTech Connect

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.

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

441

Groundwater-transported dissolved organic nitrogen exports from coastal watersheds  

USGS Publications Warehouse

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.

Kroeger, K.D.; Cole, M.L.; Valiela, I.

2006-01-01

442

Yucca Mountain Area Saturated Zone Dissolved Organic Carbon Isotopic Data  

SciTech Connect

Groundwater samples in the Yucca Mountain area were collected for chemical and isotopic analyses and measurements of water temperature, pH, specific conductivity, and alkalinity were obtained at the well or spring at the time of sampling. For this project, groundwater samples were analyzed for major-ion chemistry, deuterium, oxygen-18, and carbon isotopes of dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC). The U.S. Geological Survey (USGS) performed all the fieldwork on this project including measurement of water chemistry field parameters and sample collection. The major ions dissolved in the groundwater, deuterium, oxygen-18, and carbon isotopes of dissolved inorganic carbon (DIC) were analyzed by the USGS. All preparation and processing of samples for DOC carbon isotopic analyses and geochemical modeling were performed by the Desert Research Institute (DRI). Analysis of the DOC carbon dioxide gas produced at DRI to obtain carbon-13 and carbon-14 values was conducted at the University of Arizona Accelerator Facility (a NSHE Yucca Mountain project QA qualified contract facility). The major-ion chemistry, deuterium, oxygen-18, and carbon isotopes of DIC were used in geochemical modeling (NETPATH) to determine groundwater sources, flow paths, mixing, and ages. The carbon isotopes of DOC were used to calculate groundwater ages that are independent of DIC model corrected carbon-14 ages. The DIC model corrected carbon-14 calculated ages were used to evaluate groundwater travel times for mixtures of water including water beneath Yucca Mountain. When possible, groundwater travel times were calculated for groundwater flow from beneath Yucca Mountain to down gradient sample sites. DOC carbon-14 groundwater ages were also calculated for groundwaters in the Yucca Mountain area. When possible, groundwater travel times were estimated for groundwater flow from beneath Yucca Mountain to down gradient groundwater sample sites using the DOC calculated groundwater ages. The DIC calculated groundwater ages were compared with DOC calculated groundwater ages and both of these ages were compared to travel times developed in ground-water flow and transport models. If nuclear waste is stored in Yucca Mountain, the saturated zone is the final barrier against the release of radionuclides to the environment. The most recent rendition of the TSPA takes little credit for the presence of the saturated zone and is a testament to the inadequate understanding of this important barrier. If radionuclides reach the saturated zone beneath Yucca Mountain, then there is a travel time before they would leave the Yucca Mountain area and flow down gradient to the Amargosa Valley area. Knowing how long it takes groundwater in the saturated zone to flow from beneath Yucca Mountain to down gradient areas is critical information for potential radionuclide transport. Radionuclide transport in groundwater may be the quickest pathway for radionuclides in the proposed Yucca Mountain repository to reach land surface by way of groundwater pumped in Amargosa Valley. An alternative approach to ground-water flow and transport models to determine the travel time of radionuclides from beneath Yucca Mountain to down gradient areas in the saturated zone is by carbon-14 dating of both inorganic and organic carbon dissolved in the groundwater. A standard method of determining ground-water ages is to measure the carbon-13 and carbon-14 of DIC in the groundwater and then correct the measured carbon-14 along a flow path for geochemical reactions that involve carbon containing phases. These geochemical reactions are constrained by carbon-13 and isotopic fractionations. Without correcting for geochemical reactions, the ground-water ages calculated from only the differences in carbon-14 measured along a flow path (assuming the decrease in carbon-14 is due strictly to radioactive decay) could be tens of thousands of years too old. The computer program NETPATH, developed by the USGS, is the best geochemical program for correcting carbon-14 activities for geochemical r

Thomas, James; Decker, David; Patterson, Gary; Peterman, Zell; Mihevc, Todd; Larsen, Jessica; Hershey, Ronald

2007-06-25

443

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

NASA Astrophysics Data System (ADS)

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.

Shank, G. Christopher; Evans, Anne

2011-07-01

444

Agent-based modeling of hyporheic dissolved organic carbon transport and transformation  

NASA Astrophysics Data System (ADS)

Dissolved organic carbon (DOC) is a complex suite of organic compounds present in natural ecosystems, and is particularly studied in river and stream systems. The hyporheic zone (HZ), a region of surface water-shallow groundwater exchange, has been identified as a hotspot of DOC processing and is generally regarded as a net sink of organic matter. More recent studies into stream DOC have shifted to examining DOC quality rather than bulk quantity. DOC quality variability has been linked to hydrologic and climatic variability, both focuses of current climate change research. A new agent-based model in the NetLogo modeling environment couples hydrologic transport with chemical and biological transformation of DOC to simulate changing DOC quality in hyporheic flow. A pore-scale model implements a Lattice Boltzmann fluid dynamic model and surficial interactions to simulate sorption and microbial uptake. Upscaled to a stream meander scale, this model displays spatial variation and evolution of DOC quality. Model output metrics are correlated to field sample analytical results from a hyporheic meander of the East Fork Jemez River, Sandoval Co., NM.

Gabrielsen, P. J.; Wilson, J. L.; Pullin, M.

2011-12-01

445

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

SciTech Connect

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.

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

446

Dissolved Neodymium Isotopes and Concentrations in the South Pacific  

NASA Astrophysics Data System (ADS)

The isotopic composition of dissolved Neodymium (expressed as ?Nd) in seawater is becoming increasingly established as a tracer for present and past water mass structure and flow paths. The South Pacific represents the largest sector of the Southern Ocean and harbors major areas of bottom and intermediate water mass formation and is therefore a key area for understanding present and past deep ocean circulation. While more dissolved Nd data are becoming available from different ocean basins, the South Pacific is still understudied with respect to the distribution of Nd isotopes and concentrations. In this study we have analyzed dissolved Nd isotopes and concentrations from 11 water column profiles across the South Pacific between 46°S and 69°S that sample all water masses. Our data show that the bottom water in the vicinity of the Ross Sea (Ross Sea Bottom water, RSBW) is represented by an ?Nd value of ~ -7, while the overlying Circumpolar Deep Water (CDW) carries a signature of ?Nd = -8 to -9. The characteristic Nd isotopic signal of RSBW can be tracked along its flow path into the southeast Pacific where it progressively looses its signal through interaction with ambient CDW. The easternmost stations, closer to South America, exhibit an excursion towards radiogenic ?Nd at ?2000 m water depth. This change towards more positive ?Nd coincides with low oxygen and high phosphate concentrations representing Pacific Deep Water (PDW) and possibly indicates water mass mixing of CDW with more radiogenic PDW. While the Nd isotopic composition shows apparent variations between stations and different water masses, the concentration profiles show a rather uniform and gradual increase with depth, a pattern typical for open ocean settings. Spatial and vertical contrasts in Nd isotopic values throughout the South Pacific indicate that Nd isotopes can be used as a water mass tracer in this region. It is reasonable to infer that local lithology in the Ross Sea influenced the Nd isotopic signature of newly formed RSBW, thereby tagging it with an ?Nd signal distinct from other water masses in the South Pacific. This suggests that ?Nd can be used in downcore studies to better understand past fluctuations of deep water advection in the South Pacific.

Basak, C.; Pahnke, K.

2013-12-01

447

Emittance simulations Emittance simulations  

E-print Network

1 Emittance simulations Emittance simulations Pavel Snopok IIT/Fermilab April 8, 2011 #12;2 Emittance simulations Introduction Emittance calculation = cov(x, px , y, py , t, -E); 6D = c m3 det, where J is a block diagonal matrix made up of three blocks J2 = 0 1 -1 0 . |1|, |2|, |3| ­ eigen-emittances

McDonald, Kirk

448

Process performance of the pilot-scale in situ vitrification of a simulated waste disposal site at the Oak Ridge National Laboratory  

SciTech Connect

Process feasibility studies have been successfully performed on three developmental scales to determine the potential for applying in situ vitrification to intermediate-level (low-level) waste placed in seepage pits and trenches at Oak Ridge National Laboratory (ORNL). In the laboratory, testing was performed in crucibles containing a mixture of 50% ORNL soil and 50% limestone. In an engineering-scale test at Pacific Northwest Laboratory a /1/12/-scale simulation of an ORNL waste trench was constructed and vitrified, resulting in a waste product containing soil and limestone concentrations of 68 wt % and 32 wt %, respectively. In the pilot-scale test a /3/8/-scale simulation of the same trench was constructed and vitrified at ORNL, resulting in soil and limestone concentrations of 80% and 20%, respectively, in the waste product. Results of the three scales of testing indicate that the ORNL intermediate-level (low-level) waste sites can be successfully processed by in situ vitrification; the waste form will retain significant quantities of the cesium and strontium. Because cesium-137 and strontium-90 are the major components of the radionuclide inventory in the ORNL seepage pits and trenches, final field process decontamination factors (i.e., losses to the off-gas system relative to the waste inventory) of 1.0 E + 4 are desired to minimize activity buildup in the off-gas system. 17 refs., 34 figs., 13 tabs.

Carter, J.G.; Koegler, S.S.; Bates, S.O.

1988-06-01

449

Effect of dissolved oxygen on phenols breakthrough from GAC adsorbers  

SciTech Connect

The study demonstrates that molecular oxygen plays an important role in the adsorption of organic compounds from water by activated carbon. It was determined that the adsorptive capacity of granular activated carbon (GAC) for o-cresol can increase by almost 200% as a result of the presence of molecular oxygen in the test environment (oxic conditions). This increase in adsorptive capacity is not due to biological activity but can be totally attributed to the polymerization of o-cresol on the carbon surface under oxic conditions. The rate of adsorbate polymerization is such that the presence of molecular oxygen does not influence adsorption kinetics during the first 12 hours of adsorbent-adsorbate contact. However, the concentration of dissolved oxygen in the feed to a GAC adsorber can significantly influence the breakthrough of adsorbate. (Copyright (c) 1992 IAWPRC.)

Vidic, R.D.; Suidan, M.T.

1992-01-01

450

Bacterial biomarkers thermally released from dissolved organic matter  

USGS Publications Warehouse

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.

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

2006-01-01

451

Why dissolved organic matter (DOM) enhances photodegradation of methylmercury  

SciTech Connect

Methylmercury (MeHg) is known to degrade photochemically, but it remains unclear what roles naturally dissolved organic matter (DOM) and complexing organic ligands play in MeHg photodegradation. Here we investigate the rates and mechanisms of MeHg photodegradation using DOM samples with varying oxidation states and origins as well as organic ligands with known molecular structures. All DOM and organic ligands increased MeHg photodegradation under solar irradiation, but the first-order rate constants varied depending on the oxidation state of DOM and the type and concentration of the ligands. Compounds containing both thiols and aromatics (e.g., thiosalicylate and reduced DOM) increased MeHg degradation rates far greater than those containing only aromatic or thiol functional groups (e.g., salicylate or glutathione). Our results suggest that, among other factors, the synergistic effects of thiolate and aromatic moieties in DOM greatly enhance MeHg photodegradation.

Qian, Yun [ORNL; Yin, Xiangping Lisa [ORNL; Brooks, Scott C [ORNL; Liang, Liyuan [ORNL; Gu, Baohua [ORNL