These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

Methane oxidation in a crude oil contaminated aquifer: Delineation of aerobic reactions at the plume fringes  

USGS Publications Warehouse

High resolution direct-push profiling over short vertical distances was used to investigate CH4 attenuation in a petroleum contaminated aquifer near Bemidji, Minnesota. The contaminant plume was delineated using dissolved gases, redox sensitive components, major ions, carbon isotope ratios in CH4 and CO2, and the presence of methanotrophic bacteria. Sharp redox gradients were observed near the water table. Shifts in ??13CCH4 from an average of - 57.6??? (?? 1.7???) in the methanogenic zone to - 39.6??? (?? 8.7???) at 105 m downgradient, strongly suggest CH4 attenuation through microbially mediated degradation. In the downgradient zone the aerobic/anaerobic transition is up to 0.5 m below the water table suggesting that transport of O2 across the water table is leading to aerobic degradation of CH4 at this interface. Dissolved N2 concentrations that exceeded those expected for water in equilibrium with the atmosphere indicated bubble entrapment followed by preferential stripping of O2 through aerobic degradation of CH4 or other hydrocarbons. Multivariate and cluster analysis were used to distinguish between areas of significant bubble entrapment and areas where other processes such as the infiltration of O 2 rich recharge water were important O2 transport mechanisms. ?? 2011 Elsevier B.V. All rights reserved.

Amos, R.T.; Bekins, B.A.; Delin, G.N.; Cozzarelli, I.M.; Blowes, D.W.; Kirshtein, J.D.

2011-01-01

2

Plume Delineation of a Pulp and Paper Mill Outfall  

E-print Network

#12;Plume Delineation of a Pulp and Paper Mill Outfall using Airborne Multispectral Imagery) were acquired April 61993 over the Scott Paper Pulp and Paper Mill on the Fraser River, near Vancouver, British Columbia coinciding with a conventional in situ dye dispersion study conducted independently

3

ModBack - simplified contaminant source zone delineation using backtracking  

NASA Astrophysics Data System (ADS)

Contaminated groundwater poses a serious threat to drinking water resources all over the world. Even though contaminated water might be detected in observation wells, a proper clean up is often only successful if the source of the contamination is detected and subsequently removed, contained or remediated. The high costs of groundwater remediation could be possibly significantly reduced if, from the outset, a focus is placed on source zone detection. ModBack combines several existing modelling tools in one easy to use GIS-based interface helping to delineate potential contaminant source zones in the subsurface. The software is written in Visual Basic 3.5 and uses the ArcObjects library to implement all required GIS applications. It can run without modification on any Microsoft Windows based PC with sufficient RAM and at least Microsoft .NET Framework 3.5. Using ModBack requires additional installation of the following software: Processing Modflow Pro 7.0, ModPath, CSTREAM (Bayer-Raich et al., 2003), Golden Software Surfer and Microsoft Excel. The graphical user interface of ModBack is separated into four blocks of procedures dealing with: data input, groundwater modelling, backtracking and analyses. Geographical data input includes all georeferenced information pertaining to the study site. Information on subsurface contamination is gathered either by conventional sampling of monitoring wells or by conducting integral pumping tests at control planes with a specific sampling scheme. Hydraulic data from these pumping tests together with all other available information are then used to set up a groundwater flow model of the study site, which provides the flow field for transport simulations within the subsequent contamination backtracking procedures, starting from the defined control planes. The backtracking results are then analysed within ModBack. The potential areas of contamination source presence or absence are determined based on the procedure used by Jarsjö et al. (2005). The contaminant plume length can be estimated using plume length statistics, first order rate degradation equations or calculations based on site specific hydraulic and chemical parameters. Furthermore, an analytical tool is included to identify the distribution of contaminants across a control plane. All relevant output can be graphically displayed and saved as vector data to be later used in GIS software. ModBack has been already used to delimit the zones of source presence or absence at several test sites. With ModBack, a tool is now available which enables environmental consultants, engineers and environmental agencies to delineate possible sources of contamination already at the planning stage of site investigation and remediation measures, helping to significantly reduce costs of contaminated site management. Bayer-Raich, M., Jarsjö, J., Holder, T. and Ptak, T. (2003): "Numerical estimations of contaminant mass flow rate based on concentration measurements in pumping wells", ModelCare 2002: A Few Steps Closer to Reality, IAHS Publication No. 277, 10-16. Jarsjö, J., Bayer-Raich, M., Ptak, T. (2005): "Monitoring groundwater contamination and delineating source zones at industrial sites: Uncertainty analyses using integral pumping tests", Journal of Contaminant Hydrology, 79, 107-134

Thielsch, K.; Herold, M.; Ptak, T.

2012-12-01

4

A microbial fuel cell in contaminated ground delineated by electrical self-potential and normalized induced polarization data  

Microsoft Academic Search

There is a growing interest in the use of geophysical methods to aid investigation and monitoring of complex biogeochemical environments, for example delineation of contaminants and microbial activity related to land contamination. We combined geophysical monitoring with chemical and microbiological analysis to create a conceptual biogeochemical model of processes around a contaminant plume within a manufactured gas plant site. Self-potential,

R. Doherty; B. Kulessa; A. S. Ferguson; M. J. Larkin; L. A. Kulakov; R. M. Kalin

2010-01-01

5

Modelling of ion thruster plume contamination  

Microsoft Academic Search

While the potential problems of spacecraft contamination by the effluents of electric propulsion thrusters have been known for some time, the limitations of ground experiments, and until recently, computational power, have prevented accurate assessments and predictions of spacecraft contamination. We are developing a hybrid plasma particle-in-cell (PIC) code with a Monte Carlo collision operator to model the plume of an

R. I. Samanta Roy; D. E. Hastings

1993-01-01

6

Monitoring Groundwater Contaminant Plumes Using Airborne Geophysical Data  

NASA Astrophysics Data System (ADS)

Under the European Union Water Framework Directive, Member States are required to assess water quality across both surface water and groundwater bodies. Subsurface pollution plumes, originating from a variety of sources, pose a significant direct risk to water quality. The monitoring and characterisation of groundwater contaminant plumes is generally invasive, time consuming and expensive. In particular, adequately capturing the contaminant plume with monitoring installations, when the extent of the feature is unknown and the presence of contamination is only evident from indirect observations, can be prohibitively expensive. This research aims to identify the extent and nature of subsurface contaminant plumes using airborne geophysical survey data. This data was collected across parts of the island of Ireland within the scope of the original Tellus and subsequent Tellus Border projects. The rapid assessment of the airborne electro-magnetic (AEM) data allowed the identification of several sites containing possible contaminant plumes. These AEM anomalies were assessed through the analysis of existing site data and field site inspections, with areas of interest being examined for metallic structures that could affect the AEM data. Electrical resistivity tomography (ERT), ground penetrating radar (GPR) and ground-based electro-magnetic (EM) surveys were performed to ground-truth existing airborne data and to confirm the extent and nature of the affected area identified using the airborne data. Groundwater and surface water quality were assessed using existing field site information. Initial results collected from a landfill site underlain by basalt have indicated that the AEM data, coupled with ERT and GPR, can successfully be used to locate possible plumes and help delineate their extent. The analysis of a range of case study sites exhibiting different geological and environmental settings will allow for the development of a consistent methodology for examining the airborne data for the detection of groundwater contaminant plumes. This will provide a basis for assessing the influence that drift and bedrock geology exert on the feasibility of using Tellus airborne data as a plume monitoring tool. This research will facilitate a conjunctive approach for the detection and monitoring of pollution sources adversely affecting water bodies, as well as improve the targeting of costly intrusive monitoring and restoration efforts.

Robinson, Martin; Oftendinger, Ulrich; Ruffell, Alastair; Cowan, Marie; Cassidy, Rachel; Comte, Jean-Christophe; Wilson, Christopher; Desissa, Mohammednur

2013-04-01

7

RAPID REMOVAL OF A GROUNDWATER CONTAMINANT PLUME.  

USGS Publications Warehouse

A groundwater management model is used to design an aquifer restoration system that removes a contaminant plume from a hypothetical aquifer in four years. The design model utilizes groundwater flow simulation and mathematical optimization. Optimal pumping and injection strategies achieve rapid restoration for a minimum total pumping cost. Rapid restoration is accomplished by maintaining specified groundwater velocities around the plume perimeter towards a group of pumping wells located near the plume center. The model does not account for hydrodynamic dispersion. Results show that pumping costs are particularly sensitive to injection capacity. An 8 percent decrease in the maximum allowable injection rate may lead to a 29 percent increase in total pumping costs.

Lefkoff, L. Jeff; Gorelick, Steven M.

1985-01-01

8

Delineation of a landfill leachate plume using shallow electromagnetic and ground-penetrating radar surveys  

SciTech Connect

Leachate plumes are often more electrically conductive than the surrounding host pore waters, and thus can be detected using shallow electromagnetic (EM) methods. The depth of penetration of ground penetrating radar (GPR) is controlled to a large extent by the electrical conductivity. Conductive leachate plumes will appear as ``blank`` areas in the radar profiles, because the radar energy is more severely attenuated in the region of the leachate plume. The authors present here the results of EM and GPR Surveys carried out in an area adjacent to a landfill site. Previous resistivity surveys indicated the presence of a leachate plume originating from an early stage of the landfill operation. The shallow EM and GPR surveys were carried out, in part, to confirm and refine the resistivity results, and to delineate the spatial extent of the plume. The surficial sediments are coastal sands, and the dune topography has an effect on the EM results, even though the variations in elevation are, in general, no more than 3 m. Besides the leachate plume, numerous conductivity highs and lows are present, which are at least coarsely correlated with topographic lows and highs. Following the empirical procedure outlined by Monier-Williams et al. (1990), the topographic effects have been removed, and the plume is better isolated and delineated. A possible second, weaker leachate plume has been identified, emanating from the current landfill operation. The second plume may follow a channel that was masked by the overlying dune sands. The leading edge of the primary leachate plume is moving to the south-southeast at a rate of 14 to 15 m/yr.

Nobes, D.C.; Armstrong, M.J. [Univ. of Canterbury, Christchurch (New Zealand); Broadbent, M. [Broadbent (Michael), Christchurch (New Zealand)

1994-12-31

9

Monopropellant thruster exhaust plume contamination measurements  

NASA Technical Reports Server (NTRS)

The potential spacecraft contaminants in the exhaust plume of a 0.89N monopropellant hydrazine thruster were measured in an ultrahigh quartz crystal microbalances located at angles of approximately 0 deg, + 15 deg and + or - 30 deg with respect to the nozzle centerline. The crystal temperatures were controlled such that the mass adhering to the crystal surface at temperatures of from 106 K to 256 K could be measured. Thruster duty cycles of 25 ms on/5 seconds off, 100 ms on/10 seconds off, and 200 ms on/20 seconds off were investigated. The change in contaminant production with thruster life was assessed by subjecting the thruster to a 100,000 pulse aging sequence and comparing the before and after contaminant deposition rates. The results of these tests are summarized, conclusions drawn, and recommendations given.

Baerwald, R. K.; Passamaneck, R. S.

1977-01-01

10

Reaction front formation in contaminant plumes  

NASA Astrophysics Data System (ADS)

The formation of successive fronts in contaminated groundwater plumes by subsoil bacterial action is a commonly accepted feature of their propagation, but it is not obviously clear from a mathematical standpoint quite how such fronts are formed or propagate. In this paper we show that these can be explained by combining classical reaction-diffusion theory involving just two reactants (oxidant and reductant), and a secondary reaction in which a reactant on one side of such a front is (re-)formed on the other side of the front via diffusion of its product across the front. We give approximate asymptotic solutions for the reactant profiles, and the propagation rate of the front.

Cribbin, Laura B.; Winstanley, Henry F.; Mitchell, Sarah L.; Fowler, Andrew C.; Sander, Graham C.

2014-12-01

11

Pollutant plume delineation from tree core sampling using standardized ranks.  

PubMed

There are currently contradicting results in the literature about the way chloroethene (CE) concentrations from tree core sampling correlate with those from groundwater measurements. This paper addresses this issue by focusing on groundwater and tree core datasets in CE contaminated site, Czech Republic. Preliminary analyses revealed strongly and positively skewed distributions for the tree core dataset, with an intra-tree variability accounting for more than 80% of the total variability, while the spatial analyses based on variograms indicated no obvious spatial pattern for CE concentration. Using rank transformation, it is shown how the results were improved by revealing the initially hidden spatial structure for both variables when they are handled separately. However, bivariate analyses based on cross-covariance functions still failed to indicate a clear spatial correlation between groundwater and tree core measurements. Nonetheless, tree core sampling and analysis proved to be a quick and inexpensive semi-quantitative method and a useful tool. PMID:22243856

Wahyudi, Agung; Bogaert, Patrick; Trapp, Stefan; Machá?ková, Ji?ina

2012-03-01

12

Associations of free-living bacteria and dissolved organic compounds in a plume of contaminated groundwater  

USGS Publications Warehouse

Associations of free-living bacteria (FLB) and dissolved organic contaminants in a 4-km-long plume of sewage-contaminated groundwater were investigated. Abundance of FLB in the core of the plume (as delineated by maximum specific conductance) steadily decreased in the direction of flow from a point 0.25 km downgradient from the source to the toe of the plume. At 0.25 km downgradient, FLB comprised up to 31% of the total bacterial population, but constituted < 7% of the population at 2 km downgradient. Abundance of FLB correlated strongly (r = 0.80 n = 23) with total dissolved organic carbon (DOC) in contaminated groundwater between 0.64 and 2.1 km downgradient, although distributions of individual contaminants such as di-, tri- and tetrachloroethene were highly variable, and their association with FLB less clear. Numbers of FLB in the downgradient portion of the plume which is contaminated with branched-chain alkylbenzenesulfonate (ABS) surfactants were low (< 5??108/L) in spite of relatively high levels of DOC (up to 4 mg/L). However, abundance of FLB correlated strongly with non-surfactant DOC along vertical transects through the plume. The ratio of FLB to DOC and the ratio of FLB to attached bacteria generally decreased in the direction of flow and, consequently, with the age of the organic contaminants.

Harvey, R.W.; Barber, L.B., II

1992-01-01

13

Reaction front formation in contaminant plumes.  

PubMed

The formation of successive fronts in contaminated groundwater plumes by subsoil bacterial action is a commonly accepted feature of their propagation, but it is not obviously clear from a mathematical standpoint quite how such fronts are formed or propagate. In this paper we show that these can be explained by combining classical reaction-diffusion theory involving just two reactants (oxidant and reductant), and a secondary reaction in which a reactant on one side of such a front is (re-)formed on the other side of the front via diffusion of its product across the front. We give approximate asymptotic solutions for the reactant profiles, and the propagation rate of the front. PMID:25461883

Cribbin, Laura B; Winstanley, Henry F; Mitchell, Sarah L; Fowler, Andrew C; Sander, Graham C

2014-10-25

14

Groundwater contamination downstream of a contaminant penetration site. I. Extension-expansion of the contaminant plume  

USGS Publications Warehouse

This study concerns the possible use of boundary layer (BL) approach for the analysis and evaluation of contaminant transport in groundwater due to contaminant penetration into the groundwater aquifer through a site of limited size. The contaminant penetration may occur through either the upper (surface) or lower (bedrock) boundary of the aquifer. Two general cases of contaminant penetration mechanisms are considered: (1) the contaminant is transferred through an interface between a contaminating and freshwater fluid phases, and (2) the contaminant arrives at groundwater by leakage and percolation. For the purpose of BL evaluation the contaminant plume is divided into three different sections: (1) the penetration section, (2) the extension-expansion section, and (3) the spearhead section. In each section a different BL method approach yields simple analytical expressions for the description of the contaminant plume migration and contaminant transport. Previous studies of the BL method can be directly applied to the evaluation of contaminant transport at the contaminant penetration section. The present study extends those studies and concerns the contaminant transport in the two other sections, which are located downstream of the penetration section. This study shows that the contaminant concentration profiles in sections 2 and 3 incorporate two BLs: (1) an inner BL adjacent to the aquifer bottom or surface boundary, and (2) an outer BL, which develops above or below the inner one. The method developed in the present study has been applied to practical issues concerning salinity penetration into groundwater in south central Kansas.

Rubin, H.; Buddemeier, R.W.

2002-01-01

15

Comparison of three field screening techniques for delineating petroleum hydrocarbon plumes in groundwater at a site in the southern Carson Desert, Nevada  

SciTech Connect

Three types of field screening techniques used in the characterization of potentially contaminated sites at Naval Air Station Fallon, Nevada, are compared. The methods and results for each technique are presented. The three techniques include soil-gas surveys, electromagnetic geophysical surveys, and groundwater test hole screening. Initial screening at the first study site included two soil-gas surveys and electromagnetic geophysical studies. These screening methods identified I areas of contamination; however, results were inconclusive. Therefore groundwater test hole screening was performed. Groundwater screening consisted of auger drilling down to the shallow alluvial aquifer. Groundwater samples were collected from the open drill hole with a bailer. On-site head-space analyses for volatile organic compounds (VOCS) were performed using a portable gas chromatograph (GC). Five areas of floating petroleum hydrocarbon product were identified along with the overall dissolved contaminant plume boundaries. Well placement was re-evaluated, and well sites were relocated based on the screening information. The most effective technique for identification of petroleum hydrocarbon-contaminant plumes was groundwater test hole screening. Groundwater screening was subsequently performed at 19 other sites. A total of 450 test holes were analyzed resulting in the delineation of six plumes.

Smuin, D.R.

1993-01-01

16

Delineation of ground-water contamination using soil-gas analyses near Jackson, Tennessee  

USGS Publications Warehouse

An investigation of the ground-water resources near Jackson, West Tennessee, was conducted during 1988-89. The study included determination of the occurrence of contaminants in the shallow aquifer using soil-gas analyses in the unsaturated zone. Between 1980 and 1988, an underground fuel-storage tank leaked about 3,000 gallons of unleaded fuel to the water table about 4 feet below land surface. A survey of soil gas using a gas chromatograph equipped with a photoionization detector showed concentrations of volatile organic compounds greater than IO, 000 parts per million near the leak These compounds were detected in an area about 240 feet long and 110 feet wide extending west from the point source. The chromatograms provided two distinct 'fingerprints' of volatile organic compounds. The first revealed the presence of benzene, toluene, andxylenes, which are constituents of unleaded fuel, in addition to other volatile compounds, in soil gas in the area near the leak The second did not reveal any detectable benzene, toluene, or xylenes in the soil-gas samples, but showed the presence of other unidentified volatile organic compounds in soil gas north of the storage tank. The distribution of total concentrations of volatile organic compounds in the unsaturated zone indicated that a second plume about 200 feet long and 90 feet wide was present about 100 feet north of the storage tank The second plume could have been the result of previous activities at this site during the 1950's or earlier. Activities at the site are believed to have included storage of solvents used at the nearby railyard and flushing of tanks containing tar onto a gravel-covered parking area. The delineation of these plumes has shown that soil-gas analyses can be a useful technique for identifying areas of contamination with volatile organic compounds in shallow water-table aquifers and may have broad applications in similar situations where the water table is relatively close to the surface.

Lee, R.W.

1991-01-01

17

Hydrogeophysical investigations of the former S-3 ponds contaminant plumes  

SciTech Connect

At the Oak Ridge Integrated Field Research Challenge site, near Oak Ridge, Tennessee, contaminants from the former S-3 ponds have infiltrated the shallow saprolite for over 60 years. Two- and three-dimensional DC-resistivity tomography is used to characterize the number and location of the main contaminant plumes, which include high concentration of nitrate. These contaminant plumes have typically an electrical resistivity in the range 2 20 ohm-m while the background saprolite resistivity is in the range 60 120 ohm-m, so the difference of resistivity can be easily mapped using DC-resistivity tomography to locate the contaminant pathways. We develop a relationship to derive the in situ nitrate concentrations from the 3D resistivity tomograms accounting for the effect of surface conductivity. The footprint of the contamination upon the resistivity is found to be much stronger than the local variations associated with changes in the porosity and the clay content. With this method, we identified a total of five main plumes (termed CP1 to CP5). Plume CP2 corresponds to the main plume in terms of nitrate concentration ( 50,000 ). We also used an active time constrained approach to perform time-lapse resistivity tomography over a section crossing the plumes CP1 and CP2. The sequence of tomograms is used to determine the changes in the nitrate concentrations associated with infiltration of fresh (meteoritic) water from a perched aquifer. This study highlights the importance of accounting for surface conductivity when characterizing plume distributions in clay-rich subsurface systems.

Revil, Andre [ORNL] [ORNL; Skold, Magnus E [ORNL] [ORNL; Karaoulis, Marios [Colorado School of Mines, Golden] [Colorado School of Mines, Golden; Schmutz, Myriam [Institut Polytechnique de Bordeaux] [Institut Polytechnique de Bordeaux; Hubbard, Susan S [Lawrence Berkeley National Laboratory (LBNL)] [Lawrence Berkeley National Laboratory (LBNL); Mehlhorn, Tonia L [ORNL] [ORNL; Watson, David B [ORNL] [ORNL

2013-01-01

18

Delineation of subsurface hydrocarbon contamination at a former hydrogenation plant using spectral induced polarization imaging  

NASA Astrophysics Data System (ADS)

Broadband spectral induced polarization (SIP) measurements were conducted at a former hydrogenation plant in Zeitz (NE Germany) to investigate the potential of SIP imaging to delineate areas with different BTEX (benzene, toluene, ethylbenzene, and xylene) concentrations. Conductivity images reveal a poor correlation with the distribution of contaminants; whereas phase images exhibit two main anomalies: low phase shift values (< 5 mrad) for locations with high BTEX concentrations, including the occurrence of free-phase product (BTEX concentrations > 1.7 g/l), and higher phase values for lower BTEX concentrations. Moreover, the spectral response of the areas with high BTEX concentration and free-phase products reveals a flattened spectrum in the low frequencies (< 40 Hz), while areas with lower BTEX concentrations exhibit a response characterized by a frequency peak. The SIP response was modelled using a Debye decomposition to compute images of the median relaxation-time. Consistent with laboratory studies, we observed an increase in the relaxation-time associated with an increase in BTEX concentrations. Measurements were also collected in the time domain (TDIP), revealing imaging results consistent with those obtained for frequency domain (SIP) measurements. Results presented here demonstrate the potential of the SIP imaging method to discriminate source and plume of dissolved contaminants at BTEX contaminated sites.

Flores Orozco, Adrián; Kemna, Andreas; Oberdörster, Christoph; Zschornack, Ludwig; Leven, Carsten; Dietrich, Peter; Weiss, Holger

2012-08-01

19

Groundwater contamination downstream of a contaminant penetration site. II. Horizontal penetration of the contaminant plume.  

PubMed

Part I of this study (Rubin, H.; Buddemeier, R.W. Groundwater Contamination Downstream of a Contaminant Penetration Site Part 1: Extension-Expansion of the Contaminant Plume. J. of Environmental Science and Health Part A (in press).) addressed cases, in which a comparatively thin contaminated region represented by boundary layers (BLs) developed within the freshwater aquifer close to contaminant penetration site. However, at some distance downstream from the penetration site, the top of the contaminant plume reaches the top or bottom of the aquifer. This is the location of the "attachment point," which comprises the entrance cross section of the domain evaluated by the present part of the study. It is shown that downstream from the entrance cross section, a set of two BLs develop in the aquifer, termed inner and outer BLs. It is assumed that the evaluated domain, in which the contaminant distribution gradually becomes uniform, can be divided into two sections, designated: (a) the restructuring section, and (b) the establishment section. In the restructuring section, the vertical concentration gradient leads to expansion of the inner BL at the expense of the outer BL, and there is almost no transfer of contaminant mass between the two layers. In the establishment section, each of the BLs occupies half of the aquifer thickness, and the vertical concentration gradient leads to transfer of contaminant mass from the inner to the outer BL. By use of BL approximations, changes of salinity distribution in the aquifer are calculated and evaluated. The establishment section ends at the uniformity point, downstream from which the contaminant concentration profile is practically uniform. The length of the restructuring section, as well as that of the establishment section, is approximately proportional to the aquifer thickness squared, and is inversely proportional to the transverse dispersivity. The study provides a convenient set of definitions and terminology that are helpful in visualizing the gradual development of uniform contaminant concentration distribution in an aquifer subject to contaminant plume penetration. The method developed in this study can be applied to a variety of problems associated with groundwater quality, such as initial evaluation of field data, design of field data collection, the identification of appropriate boundary conditions for numerical models, selection of appropriate numerical modeling approaches, interpretation and evaluation of field monitoring results, etc. PMID:12413211

Rubin, Hillel; Buddemeier, Robert W

2002-11-01

20

Groundwater contamination downstream of a contaminant penetration site. II. Horizontal penetration of the contaminant plume  

USGS Publications Warehouse

Part I of this study (Rubin, H.; Buddemeier, R.W. Groundwater Contamination Downstream of a Contaminant Penetration Site Part 1: Extension-Expansion of the Contaminant Plume. J. of Environmental Science and Health Part A (in press).) addressed cases, in which a comparatively thin contaminated region represented by boundary layers (BLs) developed within the freshwater aquifer close to contaminant penetration site. However, at some distance downstream from the penetration site, the top of the contaminant plume reaches the top or bottom of the aquifer. This is the location of the "attachment point," which comprises the entrance cross section of the domain evaluated by the present part of the study. It is shown that downstream from the entrance cross section, a set of two BLs develop in the aquifer, termed inner and outer BLs. It is assumed that the evaluated domain, in which the contaminant distribution gradually becomes uniform, can be divided into two sections, designated: (a) the restructuring section, and (b) the establishment section. In the restructuring section, the vertical concentration gradient leads to expansion of the inner BL at the expense of the outer BL, and there is almost no transfer of contaminant mass between the two layers. In the establishment section, each of the BLs occupies half of the aquifer thickness, and the vertical concentration gradient leads to transfer of contaminant mass from the inner to the outer BL. By use of BL approximations, changes of salinity distribution in the aquifer are calculated and evaluated. The establishment section ends at the uniformity point, downstream from which the contaminant concentration profile is practically uniform. The length of the restructuring section, as well as that of the establishment section, is approximately proportional to the aquifer thickness squared, and is inversely proportional to the transverse dispersivity. The study provides a convenient set of definitions and terminology that are helpful in visualizing the gradual development of uniform contaminant concentration distribution in an aquifer subject to contaminant plume penetration. The method developed in this study can be applied to a variety of problems associated with groundwater quality, such as initial evaluation of field data, design of field data collection, the identification of appropriate boundary conditions for numerical models, selection of appropriate numerical modeling approaches, interpretation and evaluation of field monitoring results, etc.

Rubin, H.; Buddemeier, R.W.

2002-01-01

21

OBSERVATIONS FROM CONTAMINANT PLUMES ON LONG ISLAND  

EPA Science Inventory

The aquifers of Long Island serve as a sole source drinking water supply for the entire local population of about three million people. Where the shallow Upper Glacial Aquifer has been contaminated with petroleum hydrocarbons and methyl tert-butyl ether (MTBE), intensive site ...

22

Contamination control and plume assessment of low-energy thrusters  

NASA Technical Reports Server (NTRS)

Potential contamination of a spacecraft cryogenic surface by a xenon (Xe) ion generator was evaluated. The analysis involves the description of the plume exhausted from the generator with its relative component fluxes on the spacecraft surfaces, and verification of the conditions for condensation, adsorption, and sputtering at those locations. The data describing the plume fluxes and their effects on surfaces were obtained from two sources: the tests carried out with the Xe generator in a small vacuum chamber to indicate deposits and sputter on monitor slides; and the extensive tests with a mercury (Hg) ion thruster in a large vacuum chamber. The Hg thruster tests provided data on the neutrals, on low-energy ion fluxes, on high-energy ion fluxes, and on sputtered materials at several locations within the plume.

Scialdone, John J.

1993-01-01

23

Superposition of borehole-to-surface voltage residuals for Vadose Zone plume delineation.  

PubMed

An injected tracer field experiment was conducted at the University of Idaho Ground Water Field Laboratory to evaluate the application of borehole-to-surface voltage measurements for delineation of the tracer distribution in partially saturated, fractured basalt. A tap water tracer was injected into a fracture-dominated, salt-water plume formed during a previous salt-water injection experiment. The tap water tracer was injected into a central injection well under constant hydraulic head for 34 days. The injection well was surrounded by seven test boreholes. Each borehole contained several copper wire electrodes for borehole-to-surface potential measurements between a surface grid of 224 copper sulfate, porous pot electrodes. Eight pole-pole, borehole-to-surface voltage data sets were acquired during each measurement period by energization of a selected electrode in each of the eight boreholes. Predicted voltages for a uniform earth (homogeneous and isotropic) potential model (finite difference) were subtracted from each data set (for its respective current source location), and the voltage residuals superposed to create new data sets with greater measurement sensitivity and coverage, to aid in interpretation. These data sets were collected over four measurement periods during tap water injection and four measurement periods during the subsequent 64-day drainage phase. The data were interpreted with the use of three-dimensional models and by comparisons with other electrical and hydrological observations. Results indicate that superposition of multiple data sets of voltage residuals significantly improved the lateral resolution of subsurface bulk resistivity changes that occurred over time. PMID:16298016

Osiensky, James L; Belknap, Willard J; Donaldson, Paul R

2006-01-10

24

Delineating Landfill Leachate Discharge To An Arsenic Contaminated Waterway  

EPA Science Inventory

Discharge of contaminated ground water may serve as a primary and on-going source of contamination to surface water. A field investigation was conducted at a Superfund site in Massachusetts, USA to define the locus of contaminant flux and support source identification for arseni...

25

Hall Effect Thruster Plume Contamination and Erosion Study  

NASA Technical Reports Server (NTRS)

The objective of the Hall effect thruster plume contamination and erosion study was to evaluate the impact of a xenon ion plume on various samples placed in the vicinity of a Hall effect thruster for a continuous 100 hour exposure. NASA Glenn Research Center was responsible for the pre- and post-test evaluation of three sample types placed around the thruster: solar cell cover glass, RTV silicone, and Kapton(R). Mass and profilometer), were used to identify the degree of deposition and/or erosion on the solar cell cover glass, RTV silicone, and Kapton@ samples. Transmittance, reflectance, solar absorptance, and room temperature emittance were used to identify the degree of performance degradation of the solar cell cover glass samples alone. Auger spectroscopy was used to identify the chemical constituents found on the surface of the exposed solar cell cover glass samples. Chemical analysis indicated some boron nitride contamination on the samples, from boron nitride insulators used in the body of the thruster. However, erosion outweighted contamination. All samples exhibited some degree of erosion. with the most erosion occurring near the centerline of the plume and the least occurring at the +/- 90 deg positions. For the solar cell cover glass samples, erosion progressed through the antireflective coating and into the microsheet glass itself. Erosion occurred in the solar cell cover glass, RTV silicone and Kapton(R) at different rates. All optical properties changed with the degree of erosion, with solar absorptance and room temperature emittance increasing with erosion. The transmittance of some samples decreased while the reflectance of some samples increased and others decreased. All results are consistent with an energetic plume of xenon ions serving as a source for erosion.

Jaworske, Donald A.

2000-01-01

26

Delineation of brine drilling-fluid loss in an unsaturated zone- application to contamination monitoring  

Microsoft Academic Search

The controlled-source audio frequency magnetotelluric (CSAMT) surface electromagnetic geophysical technique shows promise for delineation of zones of drilling-fluid loss and for delineating and monitoring zones of ground-water contamination in general. At the Waste Isolation Pilot Plant (WIPP) site near Carlsbad, NM, hydrology test wells are drilled with a brine drilling fluid where significant drilling-fluid losses often occur during drilling. Pre-and

Bartel

1989-01-01

27

Shuttle PRCS plume contamination analysis for Astro-2 mission  

NASA Technical Reports Server (NTRS)

The Astro-2 mission scheduled for Jan. 1995 flight is co-manifested with the Spartan experiment. The Astro instrument array consists of several telescopes operating in the UV spectrum. To obtain the desired 300 observations with the telescope array in a shorter time than the Astro-1 mission, it will be necessary to use the primary reaction control system (PRCS) rather than just the Vernier reaction control system. The high mass flow rate of the PRCS engines cause considerable concern about contamination due to PRCS plume return flux. Performance of these instruments depends heavily on the environment they encounter. The ability of the optical system to detect a remote signal depends not only on the intensity of the incoming signal, but also on the ensuing transmission loss through the optical train of the instrument. Performance of these instruments is thus dependent on the properties of the optical surface and the medium through which it propagates. The on-orbit contamination environment will have a strong influence on the performance of these instruments. The finding of a two-month study of the molecular contamination environment of the Astro-2 instruments due to PRCS thruster plumes during the planned Astro-2 mission are summarized.

Wang, Francis C.; Greene, Cindy

1993-01-01

28

Simple indicator kriging for estimating the probability of incorrectly delineating hazardous areas in a contaminated site  

SciTech Connect

The probability of incorrectly delineating hazardous areas in a contaminated site is very important for decision-makers because it indicates the magnitude of confidence that decision-makers have in determining areas in need of remediation. In this study, simple indicator kriging (SIK) was used to estimate the probability of incorrectly delineating hazardous areas in a heavy metal-contaminated site, which is located at Taoyuan, Taiwan, and is about 10 ha in area. In the procedure, the values 0 and 1 were assigned to be the stationary means of the indicator codes in the SIK model to represent two hypotheses, hazardous and safe, respectively. The spatial distribution of the conditional probability of heavy metal concentrations lower than a threshold, given each hypothesis, was estimated using SIK. Then, the probabilities of false positives ({alpha}) (i.e., the probability of declaring a location hazardous when it is not) and false negatives ({beta}) (i.e., the probability of declaring a location safe when it is not) in delineating hazardous areas for the heavy metal-contaminated site could be obtained. The spatial distribution of the probabilities of false positives and false negatives could help in delineating hazardous areas based on a tolerable probability level of incorrect delineation. In addition, delineation complicated by the cost of remediation, hazards in the environment, and hazards to human health could be made based on the minimum values of {alpha} and {beta}. The results suggest that the proposed SIK procedure is useful for decision-makers who need to delineate hazardous areas in a heavy metal-contaminated site.

Juang, K.W.; Lee, D.Y. [National Taiwan Univ., Taipei (Taiwan, Province of China). Graduate Inst. of Agricultural Chemistry] [National Taiwan Univ., Taipei (Taiwan, Province of China). Graduate Inst. of Agricultural Chemistry

1998-09-01

29

A wireless sensor network based closed-loop system for subsurface contaminant plume monitoring  

Microsoft Academic Search

A closed-loop contaminant plume monitoring system is being developed that integrates wireless sensor network based monitoring with numerical models for subsurface plumes. The system is based on a novel virtual sensor net- work architecture that supports the formation, usage, adap- tation, and maintenance of dynamic subsets of nodes. This automated monitoring system is intended to capture tran- sient plumes to

Qi Han; Anura P. Jayasumana; Tissa H. Illangasekare; Toshihiro Sakaki

2008-01-01

30

IDENTIFYING AND PREDICTING DIVING PLUME BEHAVIOR AT GROUNDWATER SITES CONTAMINATED WITH MTBE: PART 2  

EPA Science Inventory

As contaminant ground water flows downgradient from a release point, its movement is dictated by site geological conditions and hydraulics that may result in significant perpendicular contamination migration. This vertical migration pattern has been termed 'plume diving'. Under ...

31

Consolidation of the landfill stabilization and contaminant plumes focus areas  

SciTech Connect

The Assistant Secretary of the Office of Environmental Management (EM) on January 25, 1994, formally established five focus areas to implement A New Approach to Environmental Research and Technology Development at the U. S. Department of Energy (DOE) - Action Plan. The goal of this new approach was to conduct a research and technology development program that is focused on overcoming the major obstacles to cleaning up DOE sites and ensuring that the best talent within the Department and the national science communities is used. Two of the five focus areas established were Landfill Stabilization Focus Area (LSFA) and Contaminant Plumes Containment and Remediation Focus Area (PFA), which were located at the Savannah River Operations Office (SR).

Brown, J.P.; Wright, J. [Dept. of Energy, Aiken, SC (United States); Chamberlain, G.S. [Dept. of Energy, Germantown, MD (United States)

1996-12-31

32

Delineation of brine contamination in and near the East Poplar oil field, Fort Peck Indian Reservation, northeastern Montana, 2004-09  

USGS Publications Warehouse

The extent of brine contamination in the shallow aquifers in and near the East Poplar oil field is as much as 17.9 square miles and appears to be present throughout the entire saturated zone in contaminated areas. The brine contamination affects 15–37 billion gallons of groundwater. Brine contamination in the shallow aquifers east of the Poplar River generally moves to the southwest toward the river and then southward in the Poplar River valley. The likely source of brine contamination in the shallow aquifers is brine that is produced with crude oil in the East Poplar oil field study area. Brine contamination has not only affected the water quality from privately owned wells in and near the East Poplar oil field, but also the city of Poplar’s public water-supply wells. Three water-quality types characterize water in the shallow aquifers; a fourth water-quality type in the study area characterizes the brine. Type 1 is uncontaminated water that is suitable for most domestic purposes and typically contains sodium bicarbonate and sodium/magnesium sulfate as the dominant ions. Type 2 is moderately contaminated water that is suitable for some domestic purposes, but not used for drinking water, and typically contains sodium and chloride as the dominant ions. Type 3 is considerably contaminated water that is unsuitable for any domestic purpose and always contains sodium and chloride as the dominant ions. Type 3 quality of water in the shallow aquifers is similar to Type 4, which is the brine that is produced with crude oil. Electromagnetic apparent conductivity data were collected in the 106 square-mile area and used to determine extent of brine contamination. These data were collected and interpreted in conjunction with water-quality data collected through 2009 to delineate brine plumes in the shallow aquifers. Monitoring wells subsequently were drilled in some areas without existing water wells to confirm most of the delineated brine plumes; however, several possible plumes do not contain either existing water wells or monitoring wells. Analysis of groundwater samples from wells confirms the presence of 12.1 square miles of contamination, as much as 1.7 square miles of which is considerably contaminated (Type 3). Electromagnetic apparent conductivity data in areas with no wells delineate an additional 5.8 square miles of possible contamination, 2.1 square miles of which might be considerably contaminated (Type 3). Storage-tank facilities, oil wells, brine-injection wells, pipelines, and pits are likely sources of brine in the study area. It is not possible to identify discrete oil-related features as likely sources of brine plumes because several features commonly are co-located. During the latter half of the twentieth century, many brine plumes migrated beyond the immediate source area and likely mix together in modern and ancestral Poplar River valley subareas.

Thamke, Joanna N.; Smith, Bruce D.

2014-01-01

33

INORGANIC PLUME DELINEATION USING SURFACE HIGH RESOLUTION ELECTRICAL RESISTIVITY AT THE BC CRIBS & TRENCHES SITE HANFORD  

SciTech Connect

A surface resistivity survey was conducted on the Hanford Site over a waste disposal trench that received a large volume of liquid inorganic waste. The objective of the survey was to map the extent of the plume that resulted from the disposal activities approximately 50 years earlier. The survey included six resistivity transects of at least 200m, where each transect provided two-dimensional profile information of subsurface electrical properties. The results of the survey indicated that a low resistivity plume resides at a depth of approximately 25-44 m below ground surface. The target depth was calibrated with borehole data of pore-water electrical conductivity. Due to the high correlation of the pore-water electrical conductivity to nitrate concentration and the high correlation of measured apparent resistivity to pore-water electrical conductivity, inferences were made that proposed the spatial distribution of the apparent resistivity was due to the distribution of nitrate. Therefore, apparent resistivities were related to nitrate, which was subsequently rendered in three dimensions to show that the nitrate likely did not reach the water table and the bounds of the highest concentrations are directly beneath the collection of waste sites.

BENECKE, M.W.

2007-05-29

34

Delineation of recharge patterns and contaminant transport using 3H-3He in a shallow aquifer contaminated by chlorinated solvents in South Korea  

NASA Astrophysics Data System (ADS)

Stable isotopes of water and 3H-3He were used to delineate recharge patterns and contaminant transport for a granitic regolith aquifer in an industrial complex in Wonju, South Korea, that has historically been contaminated with chlorinated solvents including trichloroethene (TCE) and carbon tetrachloride (CT). Groundwater recharge mainly occurred in upgradient forested areas while little recharge occurred in the downgradient industrial areas covered with extensive sections of impermeable pavement and paddy fields. ?18O and ?D data indicated that groundwater was mainly derived from summer precipitation. The apparent groundwater ages using 3H-3He ranged from 1 to 4 yrs in the upgradient area and from 9 to 10 yrs in the downgradient area. Comparison of groundwater flow velocities based on Darcy's law and those calculated with simple mass balance models and groundwater age supported the presence of preferential pathways for TCE movement in the study area. Measureable TCE was observed in groundwater irrespective of groundwater age. Considering the 3-yr duration of the TCE spill, 14 yrs before sampling, this indicates that TCE plumes were continuously fed from sources in the unsaturated zone after the spill ended and moved downgradient without significant degradation in the aquifer.

Kaown, Dugin; Koh, Dong-Chan; Solomon, D. Kip; Yoon, Yoon-Yeol; Yang, Jaeha; Lee, Kang-Kun

2014-08-01

35

The Plume Impingement Contamination II Experiment: Motivation, Design, and Implementation Plan  

NASA Technical Reports Server (NTRS)

The International Space Station (ISS) will have a long service life during which it must be able to serve as a capable platform for a wide variety of scientific investigations. In order to provide this capability, the ISS has, at the system level, a design requirement of no more than 100 Angstroms of contaminant deposition per year from "non-quiescent" sources. Non-quiescent sources include the plumes resulting from the firing of reaction control system (ReS) engines on space vehicles visiting the ISS as well as the engines on the ISS itself. Unfortunately, good general plume contamination models do not yet exist. This is due both to the complexity of the problem, making the analytic approach difficult, and to the difficulty in obtaining empirical measurements of contaminant depositions. To address this lack of flight data, NASA Johnson Space Center is planning to fly an experiment, Plume Impingement Contamination-II, to measure the contamination deposition from the Shuttle Orbiter's primary RCS engines as a function angle from plume centerline. This represents the first direct on-orbit measurement of plume impingement contamination away from the nozzle centerline ever performed, and as such is extremely important in validating mathematical models which will be used to quantify the cumulative plume impingement contamination to the ISS over its lifetime. The paper will elaborate further upon the motivation behind making these measurements as well as present the design and implementation plan of this planned experiment.

Lumpkin, Forrest E., III; Albyn, Keith C.; Farrell, Thomas L.

2001-01-01

36

Modelling reaction front formation and oscillatory behaviour in a contaminant plume  

NASA Astrophysics Data System (ADS)

Groundwater contamination is a concern in all industrialised countries that suffer countless spills and leaks of various contaminants. Often, the contaminated groundwater forms a plume that, under the influences of regional groundwater flow, could eventually migrate to streams or wells. This can have catastrophic consequences for human health and local wildlife. The process known as bioremediation removes pollutants in the contaminated groundwater through bacterial reactions. Microorganisms can transform the contaminant into less harmful metabolic products. It is important to be able to predict whether such bioremediation will be sufficient for the safe clean-up of a plume before it reaches wells or lakes. Borehole data from a contaminant plume which resulted from spillage at a coal carbonisation plant in Mansfield, England is the motivation behind modelling the properties of a contaminant plume. In the upper part of the plume, oxygen is consumed and a nitrate spike forms. Deep inside the plume, nitrate is depleted and oscillations of organic carbon and ammonium concentration profiles are observed. While there are various numerical models that predict the evolution of a contaminant plume, we aim to create a simplified model that captures the fundamental characteristics of the plume while being comparable in accuracy to the detailed numerical models that currently exist. To model the transport of a contaminant, we consider the redox reactions that occur in groundwater systems. These reactions deplete the contaminant while creating zones of dominant terminal electron accepting processes throughout the plume. The contaminant is depleted by a series of terminal electron acceptors, the order of which is typically oxygen, nitrate, manganese, iron, sulphate and carbon dioxide. We describe a reaction front, characteristic of a redox zone, by means of rapid reaction and slow diffusion. This aids in describing the depletion of oxygen in the upper part of the plume. To describe the oscillatory behaviour of the reactant concentrations deeper in the plume, we employ the dynamics of competing bacterial populations. We show that the oscillatory behaviour, characteristic of competing populations, can describe the oscillations observed among the reactants.

Cribbin, Laura; Fowler, Andrew; Mitchell, Sarah; Winstanley, Henry

2013-04-01

37

Adaptive sampling based on the cumulative distribution function of order statistics to delineate heavy-metal contaminated soils using kriging.  

PubMed

Correctly classifying "contaminated" areas in soils, based on the threshold for a contaminated site, is important for determining effective clean-up actions. Pollutant mapping by means of kriging is increasingly being used for the delineation of contaminated soils. However, those areas where the kriged pollutant concentrations are close to the threshold have a high possibility for being misclassified. In order to reduce the misclassification due to the over- or under-estimation from kriging, an adaptive sampling using the cumulative distribution function of order statistics (CDFOS) was developed to draw additional samples for delineating contaminated soils, while kriging. A heavy-metal contaminated site in Hsinchu, Taiwan was used to illustrate this approach. The results showed that compared with random sampling, adaptive sampling using CDFOS reduced the kriging estimation errors and misclassification rates, and thus would appear to be a better choice than random sampling, as additional sampling is required for delineating the "contaminated" areas. PMID:15936860

Juang, Kai-Wei; Lee, Dar-Yuan; Teng, Yun-Lung

2005-11-01

38

Characterization of aquifer relationships by using geochemical techniques for plume delineation  

SciTech Connect

Conventional approaches to characterize aquifers at hazardous waste sites rely heavily on the installation of monitoring wells, hydraulic testing, and sampling and analysis of groundwater for contaminant concentrations. The use of geochemical techniques to determine relationships among aquifers in environmental investigations is limited, in part, because of a generally held view that these techniques may not be useful for shallow aquifers. In this paper, the authors discuss the use of (a) major ion compositions, (b) stable isotope ratios of oxygen, hydrogen, and carbon, and (c) the abundance of tritium to identify multiple aquifers, to establish the lateral extent of aquitards, and to determine hydraulic interconnections among aquifers at two hazardous waste sites. Experience with these and ongoing investigations at several other sites demonstrates that carefully conducted geochemical sampling and analysis of limited samples of groundwater provide an effective tool for hydrogeologic characterization in a variety of geologic settings.

Aggarwal, P.K.; Burton, J.C.; Rose, C.M.

1994-04-01

39

Delineation of Hydrocarbon Contamination of Soils and Sediments With Environmental Magnetic Methods: Laboratory and Field Studies  

NASA Astrophysics Data System (ADS)

Hydrocarbon contamination of soils and sediments is a worldwide environmental problem. The present research focuses on the study of magnetic properties of hydrocarbon contaminated soils and sediments using environmental magnetic methods both on field sites as well as in laboratory batch experiments. The main objectives of this research are i) to determine a possible application of magnetic proxies for the delineation of organic contamination in soils and sediments and ii) to examine the role of bacteria in changing soil magnetic properties after hydrocarbon contamination. A former oil field and a former military site which are heavily contaminated with hydrocarbons were studied. Additionally, three different types of natural clean soils were investigated in laboratory experiments by simulating hydrocarbon contamination in sterile and microbial active setups. Magnetic properties, soil properties, iron bioavailability, iron redox state and hydrocarbon content of samples were measured. Additionally, magnetic susceptibility (MS) was monitored weekly in laboratory batch set-ups during several months. Results from the field sites showed that there is an increase of MS and a good correlation between MS and hydrocarbon content. A weekly monitored MS result from the laboratory study clearly indicated~~10% change (increase as well as decrease) of initial MS of respective soils only in microbial active set-ups with saturation after a few weeks of experimental period. This depicts that there is a change of MS caused by microbial iron mineral transformation in presence of hydrocarbon contamination in soils. The results from the field study demonstrate that magnetic proxies can be used to localize hydrocarbon contamination. However, more field sites with hydrocarbon contaminated soils and sediments need to be investigated by using environmental magnetic methods for better understanding the factors driving such changes in magnetic properties.

Rijal, M. L.; Appel, E.; Porsch, K.; Kappler, A.; Blaha, U.; Petrovsky, E.

2008-12-01

40

Hydrogeophysical investigations of the former S-3 ponds contaminant plumes, Oak Ridge Integrated Field  

E-print Network

Hydrogeophysical investigations of the former S-3 ponds contaminant plumes, Oak Ridge Integrated. Hubbard4 , T. L. Mehlhorn5 , and D. B. Watson5 ABSTRACT At the Oak Ridge Integrated Field Research Challenge site, near Oak Ridge, Tennessee, contaminants from the former S-3 ponds have infiltrated

Hubbard, Susan

41

Evaluation of the ground-water contaminant plume extending from the 183-H Solar Evaporation Basins  

SciTech Connect

The 183-H Solar Evaporation Basins, located on the Hanford Site in southeastern Washington State, were used for solar concentration and storage of process wastes that consisted of nitric, sulfuric, and hydrofluoric acids, contaminated by heavy metals and radionuclides, and neutralized by sodium hydroxide. By 1977, it was apparent that leakage from the basins had reached the unconfined aquifer, causing elevated ground-water concentrations of nitrate, chromium, technetium-99, and uranium. The resulting plume is superimposed on a larger, pre-existing plume from upgradient sources that is characterized by the same contaminants, but with different relative concentrations. The plumes discharge into the Columbia River, 210 m from the basins. This study examines the relative concentration ratios of the contaminants, determines which wells in the monitoring network surrounding the basins have been affected by basin leakage, assigns reasonable plume boundaries, and shows the separate contribution of each plume to ground-water contamination downgradient from the basins. 10 refs., 8 figs., 4 tabs.

Hall, S.H.

1989-10-01

42

Studies of Plume Condensation Contamination upon Surfaces of the Terrestrial Planet Finder Spacecraft  

E-print Network

1 Studies of Plume Condensation Contamination upon Surfaces of the Terrestrial Planet Finder one craft will condense on the cryogenic surfaces of a neighboring craft, adversely affecting surfaces must be maintained at the low temperature of 40 K. There is concern that propellant expelled from

43

COLLOID MOBILIZATION AND TRANSPORT IN CONTAMINANT PLUMES: FILED EXPERIMENTS, LABORATORY EXPERIMENTS, AND MODELING  

EPA Science Inventory

The major hypothesis driving this research, that the transport of colloids in a contaminant plume is limited by the advance of the chemical agent causing colloid mobilization, was tested by (1) examining the dependence of colloid transport and mobilization on chemical perturbatio...

44

Colloid Mobilization and Transport in Contaminant Plumes: Field Experiments, Laboratory Experiments, and Modeling  

Microsoft Academic Search

The major hypothesis driving this research, that the transport of colloids in a contaminant plume is limited by the advance of the chemical agent causing colloid mobilization, was tested by (1) examining the dependence of colloid transport and mobilization on chemical perturbations, (2) assessing the relative transport of mobilized colloids and the chemicals that caused their mobilization, and (3) developing

Joseph N. Ryan; Rebecca A. Ard; Robin D. Magelky; Menachem Elimelech; Ning Sun; Ne-Zheng Sun

45

Surface and borehole electromagnetic imaging of conducting contaminant plumes  

SciTech Connect

Electromagnetic induction tomography is a promising new tool for imaging electrical conductivity variations in the earth. The EM source field is produced by induction coil (magnetic dipole) transmitters deployed at the surface or in boreholes. Vertical and horizontal component magnetic field detectors are deployed in other boreholes or on the surface. Sources and receivers are typically deployed in a configuration surrounding the region of interest. The goal of this procedure is to image electrical conductivity variations in the earth, much as x-ray tomography is used to image density variations through cross-sections of the body. Although such EM field techniques have been developed and applied, the algorithms for inverting the magnetic field data to produce the desired images of electrical conductivity have not kept pace. One of the main reasons for the lag in the algorithm development has been the fact that the magnetic induction problem is inherently three dimensional; other imaging methods such as x-ray and seismic can make use of two-dimensional approximations that are not too far from reality, but we do not have this luxury in EM induction tomography. In addition, previous field experiments were conducted at controlled test sites that typically do not have much external noise or extensive surface clutter problems often associated with environmental sites. To use the same field techniques in environments more typical of cleanup sites requires a new set of data processing tools to remove the effects of both noise and clutter. The goal of this project is to join theory and experiment to produce enhanced images of electrically conducting fluids underground, allowing better localization of contaminants and improved planning strategies for the subsequent remediation efforts. After explaining the physical context in more detail, this report will summarize the progress made in the first 18 months of this project: (1) on code development and (2) on field tests of these methods. We conclude with a brief statement of the research directions for the remainder of this three year project.

Berryman, J. G., LLNL

1998-07-01

46

Maximum entropy estimation of a Benzene contaminated plume using ecotoxicological assays.  

PubMed

Ecotoxicological bioassays, e.g. based on Danio rerio teratogenicity (DarT) or the acute luminescence inhibition with Vibrio fischeri, could potentially lead to significant benefits for detecting on site contaminations on qualitative or semi-quantitative bases. The aim was to use the observed effects of two ecotoxicological assays for estimating the extent of a Benzene groundwater contamination plume. We used a Maximum Entropy (MaxEnt) method to rebuild a bivariate probability table that links the observed toxicity from the bioassays with Benzene concentrations. Compared with direct mapping of the contamination plume as obtained from groundwater samples, the MaxEnt concentration map exhibits on average slightly higher concentrations though the global pattern is close to it. This suggest MaxEnt is a valuable method to build a relationship between quantitative data, e.g. contaminant concentrations, and more qualitative or indirect measurements, in a spatial mapping framework, which is especially useful when clear quantitative relation is not at hand. PMID:23063992

Wahyudi, Agung; Bartzke, Mariana; Küster, Eberhard; Bogaert, Patrick

2013-01-01

47

Numerical Simulation of Ion Thruster Plume Backflow for Spacecraft Contamination Assessment.  

NASA Astrophysics Data System (ADS)

A study is presented of the induced environment produced by an ion thruster, and its interactions with spacecraft. Axisymmetric and fully three-dimensional physical and numerical models of an ion thruster plume are developed and utilized to understand the physical processes involved, as well as to make useful predictions of spacecraft contamination. Components included in the model are primary beam ions, neutral propellant efflux, slow propellant ions created mainly by charge-exchange (CEX) collisions, non-propellant efflux (NPE) such as sputtered molybdenum grid metal, and neutralizing electrons. Primary focus is on the creation and transport of both the CEX propellant ions created from the beam ions and neutral propellant, and charged NPE from the thruster plume into the backflow region. The numerical model utilizes the hybrid plasma particle-in-cell (PIC) method, and the fully three-dimensional implementation is designed for multi -computer environments. Computational results of the CEX ion density and flow angles show good qualitative and quantitative agreement with experimental data. It is shown that the CEX ions created in the beam accelerate outwards and form two distinct energy populations, one with a significant backstreaming component. The effect of the background tank pressure in ground experiments, and the accelerator grid impingement current is examined. The backflow contamination from NASA's current 30 cm xenon ion thruster is investigated over the operating envelope of the thruster, and predictions for space operation are made. Scaling relationships for the backflow previously identified are confirmed. Issues regarding the electron temperature in the plume are explored, and it is shown that backflow contamination increases with electron temperature. Fully three-dimensional results with up to 17.5 million particles are presented. It is shown that the spacecraft geometry plays a strong role in the expansion of the CEX plasma. The contamination from the NPE is also examined, and calculations of surface deposition are made that are less than previous estimates based on simple models. The principle of the expanding CEX plasma cloud acting as a plasma bridge for spacecraft potential control is demonstrated. In addition, the use of a plume shield to reduce the plume backflow is simulated and found to be effective. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617 -253-5668; Fax 617-253-1690.).

Samanta Roy, Robie I.

1995-01-01

48

Exhaust plume and contamination characteristics of a bipropellant (MMH/N2O4) RCS thruster  

NASA Technical Reports Server (NTRS)

Results are presented for three recent tests in a series of thruster contamination experiments made in liquid helium-cooled environmental facility. The contaminating effects encountered on various materials, surfaces, and components, due to the exhaust products from a 5-pound thrust, bipropellant (MMH/N2O4) thruster are investigated. The angular distribution of plume effects around the periphery of the thruster established by transmittance changes of quartz samples over the wavelength range from 0.2 to 2.0 micrometer is studied, along with mass deposition rates at a specific location measured with a quartz crystal microbalance for three different experiments. Quadrupole mass spectrometer measurements of the exhaust products over the mass number range from 12 to 75; infrared transmittance measurements of contaminated samples for the wavelength range from 2.5 to 15 microns; and infrared transmittance measurements of residue from the thruster nozzle are also considered.

Spisz, E. W.; Bowman, R. L.; Jack, J. R.

1973-01-01

49

The effect of rocket plume contamination on the optical properties of transmitting and reflecting materials  

NASA Technical Reports Server (NTRS)

The preliminary results of plume contamination from a 5-pound thrust single-doublet, bipropellant rocket engine on the transmittance of quartz and the reflectance of a silicon monoxide overcoated aluminum mirror are presented. Changes in quartz transmittance were found to be significant and were due to both absorption and scattering effects. Contaminant absorption effects were predominant at the short wavelengths and scattering effects were greatest in the visible wavelengths. Measured changes in mirror reflectance were due primarily to contaminant absorption. Scattering effects were found to be as much as 9 percent of the total reflected energy from the mirror. There were no noticeable chemical or erosion effects on either the quartz or the front surface mirror.

Jack, J. R.; Spisz, E. W.; Cassidy, J. F.

1971-01-01

50

The effect of rocket plume contamination on the optical properties of transmitting and reflecting materials.  

NASA Technical Reports Server (NTRS)

The preliminary results of plume contamination from a 5-pound thrust single-doublet, bipropellant rocket engine on the transmittance of quartz and the reflectance of a silicon monoxide overcoated aluminum mirror have been presented. Changes in quartz transmittance were found to be significant and were due to both absorption and scattering effects. Contaminant absorption effects were predominant at the short wavelengths and scattering effects were greatest in the visible wavelengths. Measured changes in mirror reflectance were due primarily to contaminant absorption. Scattering effects were found to be as much as 9% of the total reflected energy from the mirror. There were no noticeable chemical or erosion effects on either the quartz or the front surface mirror.

Jack, J. R.; Spisz, E. W.; Cassidy, J. F.

1972-01-01

51

GROUND WATER SAMPLING FOR VERTICAL PROFILING OF CONTAMINANTS  

EPA Science Inventory

Accurate delineation of plume boundaries and vertical contaminant distribution are necessary in order to adequately characterize waste sites and determine remedial strategies to be employed. However, it is important to consider the sampling objectives, sampling methods, and sampl...

52

ASSESSMENT OF PLUME DIVING  

EPA Science Inventory

This presentation presents an assessment of plume diving. Observations included: vertical plume delineation at East Patchogue, NY showed BTEX and MTBE plumes sinking on either side of a gravel pit; Lake Druid TCE plume sank beneath unlined drainage ditch; and aquifer recharge/dis...

53

Integration of Predicted Atmospheric Contaminant Plumes into ArcView GIS  

SciTech Connect

The Savannah River National Laboratory (SRNL) plays a key role in emergency response scenarios in which there may be a release of atmospheric chemical or radiological contamination at the DOE's Savannah River Site (SRS). Meteorologists at SRNL use a variety of tools to predict the path of the plume and levels of contamination along the path. These predictions are used to guide field teams that take sample measurements for verification. Integration of these predicted plumes as well as field measurements into existing Geographic Information System (GIS) interactive maps provides key additional information for decision makers during an emergency. In addition, having this information in GIS format facilitates sharing the information with other agencies that use GIS. In order to be useful during an emergency, an application for converting predictions or measurements into GIS format must be automated and simple to use. Thus, a key design goal in developing such applications is ease of use. Simple menu selections and intuitive forms with graphical user interfaces are used to accomplish this goal. Applications have been written to convert two different predictive code results into ArcView GIS. Meteorologists at SRNL use the Puff/Plume code, which is tied to real-time wind data, to predict the direction and spread of the atmospheric plume for early assessment. The calculated circular puffs are converted into an ArcView polygon shapefile with attributes for predicted time, dose, and radius of the puff. The meteorologists use the more sophisticated Lagrangian Particle Dispersion Model (LPDM) to predict particle dispersion and deposition. The calculational grid is brought into ArcView as a point shapefile and then interpolated to ARC GRID format using Spatial Analyst. This GRID can then be contoured into a line shapefile, which is easily shared with other agencies. The deposition grid is also automatically contoured for values that correspond to FDA Derived Intervention Levels for beef, produce, and dairy products. Decision makers at SRS routinely use these predicted plumes to direct field teams. In the case of a strong release, this information can be used to decide whether to evacuate a particular area. Having this information in GIS format may aid the decision maker because other infrastructure information can be overlaid with geographic reference.

Koffman, Larry D.

2005-10-10

54

Detection of contaminant plumes in ground water of Long Island, New York, by electromagnetic terrain-conductivity surveys  

USGS Publications Warehouse

Electromagnetic terrain conductivity surveys were conducted at four landfills in Suffolk county and at an artificial recharge site in Nassau County to assess the feasibility of this technique for detecting contaminant plumes. The technique was successful at three of the landfills; results compared closely with those indicated by specific conductance of water from observation wells on the sites. Data from the three sites for which the technique was successful--the Horseblock Road landfill , the Manorville scavenger waste disposal facility, and the Riverhead landfill--revealed pronounced terrain conductivity anomalies that reflect known contaminant plumes. Plumes at the other two sites--Blydenburgh landfill and the East Meadow artificial recharge site--could not be detected because cultural interferences were too great and, at the Blydenburgh site, depth to water was too great. The interferences included pipelines, utility cables, and traffic. Given favorable conditions, such as high plume conductivity, lack of cultural interferences, and a depth of less than 100 ft to the plume, electromagnetic surveying can provide a rapid means of locating contaminant plumes. (Author 's abstract)

Mack, T.J.; Maus, P.E.

1986-01-01

55

Delineating the discharge zone and potential natural attenuation of a chlorinated solvent plume to a gaining lowland river: A multi-scale approach  

NASA Astrophysics Data System (ADS)

Chlorinated aliphatic hydrocarbons (CAHs), such as trichloroethene (TCE), are often recalcitrant groundwater pollutants which can form extensive dissolved plumes with the potential to impact on the quality of baseflow to rivers. There is a growing need to evaluate the risk to surface water posed by migrating plumes and the intrinsic potential for natural attenuation along contaminant flow paths through the groundwater/surface water interface (GSI). This study investigates the potential discharge of a poorly defined CAH plume to an accreting section of the River Tern (Shropshire, UK). Groundwater sampling in the area has revealed the presence of TCE (with minor chloroform and carbon tetrachloride) with maximum concentrations discovered at depths of up to 80 m in a number of deep boreholes in an unconfined sandstone aquifer hydraulically connected to the river. We aim to develop a conceptual understanding of spatial patterns of plume discharge at sub-catchment to sediment-scale and assess the potential significance of biogeochemical transformation in the river bed and riparian sediments of a baseflow-dominated lowland river. Concentrations of dissolved CAHs (including the anaerobic metabolites of TCE) were monitored in a reach-scale longitudinal channel network of liquid-liquid passive diffusion samplers, placed in direct contact with the top 10 cm of river bed sediment. Samplers comprised distilled water-filled glass vials capped by a thin (50 ?m) film of commercially available LDPE tubing. A long integration time (33 days) was selected for sampler equilibration with in-situ pore water concentrations. Results provided a plan-view reconnaissance survey of TCE distribution in the river bed and indicated tentative core and fringe zones. Spatial connectivity between ground and surface water was mapped by means of an in-situ fibre-optic distributed temperature sensor system deployed in the uppermost 10 cm of sediment spanning the investigated reach. To determine changes in concentration and composition of the plume across the GSI at sediment scale, CAHs, chloride and major ions were monitored by a network of 25 multilevel mini-piezometers installed in the bed sediments with five discrete pore water sampling levels. Additionally, 15 shallow groundwater boreholes were cored to 3 m depth in the floodplain and riparian zone of the plume-affected reach and instrumented with bag-type LDPE diffusion samplers deployed for a similar integration period. The findings of the project highlight the spatial complexity of CAH transport in a hydrostratigraphically heterogeneous GSI typical of lowland rivers. Piezometric levels and in-situ temperature observations indicate spatially variable river-aquifer connectivity with a substantial vertical component of groundwater flow through the river bed. Transformation of TCE (mainly to cis-1,2-DCE and 1,1-DCE) was found to be restricted to peat horizons and the top 20 cm of river bed sediment hosting abundant detrital organic matter. This study demonstrates the first UK application of novel in-situ technologies as part of a multi-scale investigation to characterise the behaviour and fate of an upwelling chlorinated solvent plume. Future research will focus on investigating the redox controls on biogeochemical 'hotspots' that favour transformation of TCE and the potential coupling with denitrification and production of greenhouse gases.

Weatherill, J. J.; Krause, S.; Voyce, K. J.

2012-04-01

56

Plume mass flow and optical damage distributions for an MMH/N2O4 RCS thruster. [exhaust plume contamination of spacecraft components  

NASA Technical Reports Server (NTRS)

The data obtained from two recent experiments conducted in a continuing series of experiments at the Lewis Research Center into the contamination characteristics of a 5-pound thrust MMH/N2O4 engine are presented. The primary objectives of these experiments were to establish the angular distribution of condensible exhaust products within the plume and the corresponding optical damage angular distribution of transmitting optical elements attributable to this contaminant. The plume mass flow distribution was measured by five quartz crystal microbalances (QCM's) located at the engine axis evaluation. The fifth QCM was located above the engine and 15 deg behind the nozzle exit plane. The optical damage was determined by ex-situ transmittance measurements for the wavelength range from 0.2 to 0.6 microns on 2.54 cm diameter fused silica discs also located at engine centerline elevation. Both the mass deposition and optical damage angular distributions followed the expected trend of decreasing deposition and damage as the angle between sensor or sample and the nozzle axis increased. A simple plume gas flow equation predicted the deposition distribution reasonably well for angles of up to 55 degrees. The optical damage measurements also indicated significant effects at large angles.

Spisz, E. W.; Bowman, R. L.; Jack, J. R.

1973-01-01

57

COLLOID MOBILIZATION AND TRANSPORT IN CONTAMINANT PLUMES: FIELD EXPERIMENTS, LABORATORY EXPERIMENTS, AND MODELING (EPA/600/S-99/001)  

EPA Science Inventory

The major hypothesis driving this research, that the transport of colloids in a contaminant plume is limited by the advance of the chemical agent causing colloid mobilization, was tested by (1) examining the dependence of colloid transport and mobilization on chemical perturbatio...

58

Motueka River plume facilitates transport of ruminant faecal contaminants into shellfish growing waters, Tasman Bay, New Zealand  

Microsoft Academic Search

Hydrographic and water quality surveys of the Motueka River and its river plume were conducted during a moderate flood event (peak flow of 420 m\\/s) to assess the source and fate of faecal contaminants transported into Tasman Bay. Escherichia coli (E. coli) and enterococci concentrations in the river were up to 10000 and 7300 Most Probable Number (MPN)\\/100 ml during

CD Cornelisen; PA Gillespie; M Kirs; RG Young; RW Forrest; PJ Barter; BR Knight; VJ Harwood

2011-01-01

59

Movement and fate of solutes in a plume of sewage-contaminated ground water, Cape Cod, Massachusetts  

USGS Publications Warehouse

The U.S. Geological Survey (USGS) has begun a nationwide program to study the fate of toxic wastes in groundwater. Several sites where groundwater is known to be contaminated are being studied by interdisciplinary teams of geohydrologists, chemists, and microbiologists. The objective of these studies is to obtain a thorough quantitative understanding of the physical, chemical, and biological processes of contaminant generation, migration, and attenuation in aquifers. One of the sites being studied by the USGS under this program is a plume of sewage contaminated groundwater on Cape Cod, Massachusetts. The plume was formed by land disposal of treated sewage to a glacial outwash aquifer since 1936. This report summarizes results obtained during the first year of research at the Cape Cod s under the USGS Toxic-Waste Ground-Water Contamination Program. The seven papers included in this volume were presented at the Toxic Waste Technical Meeting, Tucson, Arizona, in March 1984. They provide an integrated view of the subsurface distribution of contaminants based on the first year of research and discuss hypotheses concerning the transport processes that affect the movement of contaminants in the plume. (See W89-09053 thru W89-09059) (Lantz-PTT)

LeBlanc, D. R., (Edited By)

1984-01-01

60

DELINEATION OF SUBSURFACE HYDROCARBON CONTAMINANT DISTRIBUTION USING A DIRECT PUSH RESISTIVITY METHOD  

EPA Science Inventory

A direct push resistivity method was evaluated as a complementary screening tool to provide rapid in-situ contaminant detection to aid in better defining locations for drilling, sampling, and monitoring well installation at hazardous waste sites. Nine continuous direct push resi...

61

Delineating Fecal Contaminant Sources and Travel Times in a Karst Groundwater Basin, Inner Bluegrass Region, Kentucky  

Microsoft Academic Search

Because of preferential flowpaths via features such as sinkholes and conduits, karst aquifers are susceptible to non-point-source pollution from agricultural and urban drainage. With many karst aquifers being drinking- water sources, pathogens are contaminants of public health concern. Monitoring of microbial parameters (total coliforms [TC], atypical colonies [AC] and fecal coliform bacteria [FC]) transpired biweekly from December 2002 March 2004

J. W. Ward; T. M. Reed; A. E. Fryar; G. M. Brion

2006-01-01

62

Biodegradation Processes in a Laboratory-Scale Groundwater Contaminant Plume Assessed by Fluorescence Imaging and Microbial Analysis?  

PubMed Central

Flow reactors containing quartz sand colonized with biofilm were set up as physical model aquifers to allow degrading plumes of acetate or phenol to be formed from a point source. A noninvasive fluorescent tracer technique was combined with chemical and biological sampling in order to quantify transport and biodegradation processes. Chemical analysis of samples showed a substantial decrease in carbon concentration between the injection and outflow resulting primarily from dilution but also from biodegradation. Two-dimensional imaging of the aqueous oxygen [O2(aq)] concentration field quantified the depletion of O2(aq) within the contaminant plume and provided evidence for microbial respiration associated with biodegradation of the carbon source. Combined microbiological, chemical, and O2(aq) imaging data indicated that biodegradation was greatest at the plume fringe. DNA profiles of bacterial communities were assessed by temperature gradient gel electrophoresis, which revealed that diversity was limited and that community changes observed depended on the carbon source used. Spatial variation in activity within the plume could be quantitatively accounted for by the changes observed in active cell numbers rather than differences in community structure, the total biomass present, or the increased enzyme activity of individual cells. Numerical simulations and comparisons with the experimental data were used to test conceptual models of plume processes. Results demonstrated that plume behavior was best described by growth and decay of active biomass as a single functional group of organisms represented by active cell counts. PMID:17468279

Rees, Helen C.; Oswald, Sascha E.; Banwart, Steven A.; Pickup, Roger W.; Lerner, David N.

2007-01-01

63

Indian MORB-source mantle: not just a case of plume contamination or sediment recycling  

NASA Astrophysics Data System (ADS)

Mid-ocean ridge basalts (MORB) from the Indian Ocean have long been known for their distinctive Pb and Sr isotope compositions relative to other MORBs. Most models for their origin involve contamination of a "normal" depleted mantle by a distinctly enriched material, the most favoured being (1) recycled oceanic crust plus pelagic sediments, (2) mantle plumes and/or (3) delaminated sub-continental lithosphere. Based on quantitative mixing models, Rehkämper and Hofmann (1997) showed that recycling of an old, compositionally heterogeneous component could explain the range of Sr, Nd and Pb isotope compositions for Indian MORBs. Their model predicts that the predominant recycled component is ancient (1.5Ga) altered ocean crust, with pelagic sediment comprising less than 10% of the contaminant. However, Hf-Nd isotope systematics are difficult to explain in this way because Indian MORBs have higher eHf values (i.e. greater time-integrated depletion of Lu relative to Hf) for a given eNd than nearly all other MORBs - and considerably higher than any of the enriched materials suggested as contaminants. Essentially, Indian and Pacific MORBs form separate and parallel arrays in Nd-Hf isotope space. What is required is a mechanism that involves not only enrichment of some elements, but also relative depletion of others. Based on new Nd-Hf isotope data for Indian and Pacific MORBs from the Australian-Antarctic Discordance, we propose that the distinctive Indian MORB source composition can be explained by recycling of subduction-modified mantle. This mantle could have been generated within the convergent margin that existed off the east coast of Gondwana throughout most of the Paleozoic and Mesozoic Eras. It was subsequently recycled into the upper mantle beneath Gondwana and became the source of Indian MORBs following the break-up of the Gondwanan supercontinent. Rehkämper, M., and A. W. Hofmann, Recycled ocean crust and sediment in Indian Ocean MORB, Earth and Planetary Science Letters, 147, 93-106, 1997.

Kempton, P. D.; Pearce, J. A.

2003-04-01

64

Delineating Fecal Contaminant Sources and Travel Times in a Karst Groundwater Basin, Inner Bluegrass Region, Kentucky  

NASA Astrophysics Data System (ADS)

Because of preferential flowpaths via features such as sinkholes and conduits, karst aquifers are susceptible to non-point-source pollution from agricultural and urban drainage. With many karst aquifers being drinking- water sources, pathogens are contaminants of public health concern. Monitoring of microbial parameters (total coliforms [TC], atypical colonies [AC] and fecal coliform bacteria [FC]) transpired biweekly from December 2002 March 2004 and weekly from February October 2005 at Blue Hole Spring, which drains outlying farm lands and the town of Versailles in the Inner Bluegrass Region of Kentucky. Physicochemical parameters (discharge, temperature, specific conductance, and pH) were measured continuously during the entire period. The AC/TC ratio, which had been employed only in surface water-quality studies, was used with FC counts, precipitation and discharge data to determine sources of fecal loading to ground water as result of land-use practices. An AC/TC ratio < 10 demonstrates fresh input of fecal matter, while a larger ratio can represent a variety of occurrences, including aged fecal material input and/or lack of nutrient input into the system. AC/TC ratio data in the 2002 04 dataset behaved similarly to surface waters, with ratios > 10 during dry periods and < 10 during wet periods, while the 2005 data demonstrated a very irregular pattern. The difference in these two data sets indicated a compositional change within the groundwater basin between the two sampling periods, perhaps as a result of construction at a sewage treatment plant adjoining the spring. Solute (rhodamine WT fluorescent dye and bromide) and particle (1-?m diameter fluorescent latex microspheres) tracer tests were conducted during summer 2006 to examine contaminant mobility within the system under base-flow and storm-flow conditions. Rainfall was limited prior to the base-flow trace, totaling 0.025 cm within 2 weeks prior to the slug injection. Base-flow discharge averaged 400 m3/s and solute breakthrough began ~ 7.5 hours post injection and cleared the system after 77 hours. For the storm-flow trace, rainfall totaled 3.12 cm prior to injection, with another 9.35 cm of rainfall occurring over the two week monitoring period. Spring discharge during the storm-flow trace averaged 0.443 m3/s, with a maximum of 0.503 m3/s. Under storm-flow conditions solute breakthrough began ~ 2.33 hours post injection, with particle breakthrough beginning ~ 2.5 hours post injection. Bromide concentrations at the spring were < 0.1 ppm (the detection limit, or DL) 5.5 hours after injection, while rhodamine WT concentrations were < DL (0.1 ppb) 14 hours post injection. Microspheres were detected at the spring until 164 hours after injection. These traces demonstrate that storms in this karst basin can accelerate solute movement, and particles can remain mobile for as long as 1 week after introduction.

Ward, J. W.; Reed, T. M.; Fryar, A. E.; Brion, G. M.

2006-12-01

65

Insights into biodegradation through depth-resolved microbial community functional and structural profiling of a crude-oil contaminant plume  

USGS Publications Warehouse

Small-scale geochemical gradients are a key feature of aquifer contaminant plumes, highlighting the need for functional and structural profiling of corresponding microbial communities on a similar scale. The purpose of this study was to characterize the microbial functional and structural diversity with depth across representative redox zones of a hydrocarbon plume and an adjacent wetland, at the Bemidji Oil Spill site. A combination of quantitative PCR, denaturing gradient gel electrophoresis, and pyrosequencing were applied to vertically sampled sediment cores. Levels of the methanogenic marker gene, methyl coenzyme-M reductase A (mcrA), increased with depth near the oil body center, but were variable with depth further downgradient. Benzoate degradation N (bzdN) hydrocarbon-degradation gene, common to facultatively anaerobic Azoarcus spp., was found at all locations, but was highest near the oil body center. Microbial community structural differences were observed across sediment cores, and bacterial classes containing known hydrocarbon degraders were found to be low in relative abundance. Depth-resolved functional and structural profiling revealed the strongest gradients in the iron-reducing zone, displaying the greatest variability with depth. This study provides important insight into biogeochemical characteristics in different regions of contaminant plumes, which will aid in improving models of contaminant fate and natural attenuation rates.

Fahrenfeld, Nicole; Cozzarelli, Isabelle M.; Bailey, Zach; Pruden, Amy

2014-01-01

66

Insights into biodegradation through depth-resolved microbial community functional and structural profiling of a crude-oil contaminant plume.  

PubMed

Small-scale geochemical gradients are a key feature of aquifer contaminant plumes, highlighting the need for functional and structural profiling of corresponding microbial communities on a similar scale. The purpose of this study was to characterize the microbial functional and structural diversity with depth across representative redox zones of a hydrocarbon plume and an adjacent wetland, at the Bemidji Oil Spill site. A combination of quantitative PCR, denaturing gradient gel electrophoresis, and pyrosequencing were applied to vertically sampled sediment cores. Levels of the methanogenic marker gene, methyl coenzyme-M reductase A (mcrA), increased with depth near the oil body center, but were variable with depth further downgradient. Benzoate degradation N (bzdN) hydrocarbon-degradation gene, common to facultatively anaerobic Azoarcus spp., was found at all locations, but was highest near the oil body center. Microbial community structural differences were observed across sediment cores, and bacterial classes containing known hydrocarbon degraders were found to be low in relative abundance. Depth-resolved functional and structural profiling revealed the strongest gradients in the iron-reducing zone, displaying the greatest variability with depth. This study provides important insight into biogeochemical characteristics in different regions of contaminant plumes, which will aid in improving models of contaminant fate and natural attenuation rates. PMID:24760171

Fahrenfeld, Nicole; Cozzarelli, Isabelle M; Bailey, Zach; Pruden, Amy

2014-10-01

67

A stable isotope approach for source apportionment of chlorinated ethene plumes at a complex multi-contamination events urban site.  

PubMed

The stable carbon isotope composition of chlorinated aliphatic compounds such as chlorinated methanes, ethanes and ethenes was examined as an intrinsic fingerprint for apportionment of sources. A complex field site located in Ferrara (Italy), with more than 50years history of use of chlorinated aliphatic compounds, was investigated in order to assess contamination sources. Several contamination plumes were found in a complex alluvial sandy multi-aquifer system close to the river Po; sources are represented by uncontained former industrial and municipal dump sites as well as by spills at industrial areas. The carbon stable isotope signature allowed distinguishing 2 major sources of contaminants. One source of chlorinated aliphatic contaminants was strongly depleted in ¹³C (<-60‰) suggesting production lines which have used depleted methane for synthesis. The other source had typical carbon isotope compositions of >-40‰ which is commonly observed in recent production of chlorinated solvents. The degradation processes in the plumes could be traced interpreting the isotope enrichment and depletion of parent and daughter compounds, respectively. We demonstrate that, under specific production conditions, namely when highly chlorinated ethenes are produced as by-product during chloromethanes production, ¹³C depleted fingerprinting of contaminants can be obtained and this can be used to track sources and address the responsible party of the pollution in urban areas. PMID:24077332

Nijenhuis, Ivonne; Schmidt, Marie; Pellegatti, Eleonora; Paramatti, Enrico; Richnow, Hans Hermann; Gargini, Alessandro

2013-10-01

68

Chromium isotope variation along a contaminated groundwater plume: a coupled Cr(VI)- reduction, advective mixing perspective  

NASA Astrophysics Data System (ADS)

Chromium (Cr) is a common contaminant in groundwater, used in electroplating, leather tanning, wood preservation, and as an anti-corrosion agent. Cr occurs in two oxidation states in groundwater: Cr(VI) is highly soluble and mobile, and is a carcinogen; Cr(III) is generally insoluble, immobile and less toxic than Cr(VI). Reduction of Cr(VI) to Cr(III) is thus a central issue in approaches to Cr(VI) contaminant remediation in aquifers. Aqueous Cr(VI) occurs mainly as the chromate (CrO22-) and bichromate (HCrO2-) oxyanions, while Cr(III) is mainly "hexaquo" Cr(H2O)63+. Cr has four naturally-occurring stable isotopes: 50Cr, 52Cr, 53Cr and 54Cr. When Cr(VI) is reduced to Cr(III), the strong Cr-O bond must be broken, resulting in isotopic selection. Ellis et al. (2002) demonstrated that for reduction of Cr(VI) on magnetite and in natural sediment slurries, the change of isotopic composition of the remnant Cr(VI) pool was described by a Rayleigh fractionation model having fractionation factor ?Cr(VI)-Cr(III) = 3.4‰. We attempted to use Cr isotopes as a monitor of Cr(VI) reduction at a field site in Hinkley, California (USA) where groundwater contaminated with Cr(VI) has been under assessment for remediation. Groundwater containing up to 5 ppm Cr(VI) has migrated down-gradient from the contamination source through the fluvial to alluvial sediments to form a well-defined plume. Uncontaminated groundwater in the aquifer immediately adjacent to the plume has naturally-occurring Cr(VI) of 4 ppb or less (CH2M-Hill). In early 2006, colleagues from CH2M-Hill collected 17 samples of groundwater from within and adjacent to the plume. On a plot of ?53Cr vs. log Cr(VI), the data array is strikingly linear and differs markedly from the trend predicted for reduction of Cr(VI) in the contaminated water. There appear to be two groups of data: four samples with ?53Cr >+2‰ and Cr(VI) <4 ppb, and 13 samples with ?53Cr <+2‰ and Cr(VI) >15 ppb. Simple mixing lines between the groundwater samples having <4 ppb Cr(VI), taken to be representative of regional groundwater, and the contaminated water do not pass through the remainder of the data, discounting a simple advective mixing scenario. We hypothesize a more likely scenario that involves both Cr(VI) reduction and advective mixing. As the plume initially expands downgradient, Cr(VI) in water at the leading edge encounters reductant in the aquifer resulting in limited Cr(VI) reduction. As a result of reduction, ?53Cr of Cr(VI) remaining in solution at the leading edge increases along the "reduction" trend from 0 to ~+2‰. Inevitable mixing of this water at the leading edge with regional groundwater results in a suitable mixing end-member to combine with Cr(VI) within the plume in order to explain the bulk of the remaining data. Neither Cr(VI) reduction nor advective mixing of plume and regional groundwaters can explain the data on their own, implying an interplay of at least these two processes during plume evolution. Ellis, A.S., Johnson, T.M. and Bullen, T.D. 2002, Science, 295, 2060-2062.

Bullen, T.; Izbicki, J.

2007-12-01

69

Hydrazine engine plume contamination mapping. [measuring instruments for rocket exhaust from liquid propellant rocket engines  

NASA Technical Reports Server (NTRS)

Instrumentation for the measurement of plume exhaust specie deposition rates were developed and demonstrated. The instruments, two sets of quartz crystal microbalances, were designed for low temperature operation in the back flow and variable temperature operation in the core flow regions of an exhaust plume. These quartz crystal microbalances performed nominally, and measurements of exhaust specie deposition rates for 8400 number of pulses for a 0.1-lb monopropellant thruster are reported.

Chirivella, J. E.

1975-01-01

70

Tracing the dispersion of sediment contaminated with fallout radionuclides along the main rivers draining the contaminated plume in Fukushima Prefecture (Japan)  

NASA Astrophysics Data System (ADS)

Fukushima Dai-ichi nuclear power plant accident led to the release of important quantities of radionuclides into the environment. Several of those substances (e.g., Cs-134; Cs-137) strongly sorb onto soil particles. Resulting radiations lead to an external exposure threat associated with the spatial distribution of radionuclides. This threat, associated with the possibility of transfer of contamination to plants and direct ingestion of contaminated particles, will affect human activities such as agriculture, forest exploitation and fishing for long periods of time, depending on the half life of the radionuclides (e.g., 2 yrs for Cs-134; 30 yrs for Cs-137). Furthermore, sediment can be a preferential vector of contaminants in rivers, and its transfer can lead to the dispersion of radioactive contamination across larger areas over time. We present here preliminary results obtained during a field campaign conducted in November 2011 in a part of Fukushima Prefecture located in the main contamination plume and covering an area of about 5000 km2. We had the unique opportunity to measure and "trace" the dispersion of sediment contaminated with radionuclides shortly after the catastrophe. In total, 125 soil and sediment samples were collected along the main rivers of the area (i.e., Abukuma, Nitta, Mano, Kutchibuto and Hirose Rivers). This hydrological network drains the contamination plume located 20 to 80 km northwest of Fukushima Dai-ichi power plant. Furthermore, radiation dose rates were measured all throughout the field survey. Preliminary results show that, 8 months after the accident, radiation dose rates constitute a good proxy to trace contamination dispersion in the region, especially along rivers. Radiation dose rates varied between 0.5 µSv/h and 200 µSv/h in the field. Transfer of contaminated sediment has already started in rivers, and it was accelerated by the occurrence of violent typhoons in the region between July and October, 2011. Main gamma-emitting radionuclides detected in the area are Cs-134, Cs-137 and Ag-110m. So far, activities of Cs-134+137 measured in river sediment ranged between 3-300 kBq/kg, sometimes far exceeding the expected activity associated with the initial deposits. This pioneer investigation is crucial and constitutes a scientific prerequisite for the proposal of catchment management measures to control and limit radioactive pollution propagation. Typhoon-triggered flooding leading to subsequent sediment redistribution might generate long-lasting contamination of the food chain in this agricultural region. Keywords: Fallout radionuclides; sediment tracing; nuclear accident; catchment; river; Fukushima Dai-ichi.

Evrard, O.; Patin, J.; Lefèvre, I.; Chartin, C.; Ayrault, S.; Bonté, Ph.; Onda, Y.

2012-04-01

71

The self-potential method as a non-intrusive redox sensor in organic-rich contaminant plumes  

NASA Astrophysics Data System (ADS)

Self-potential signals correspond to passively measured electrical potential anomalies at the ground surface that provides, once filtered, the signature of polarization processes occurring in the ground. Two contributions have been recognized as providing these signals. They are the streaming potential (related to the flow of the ground water)and redox processes. We will show how the self-potential method can be used quantitatively as a non-intrusive redox sensor for the case of contaminant plumes and oil spills in the ground. In this case, we have evidenced a biogeobattery phenomenon in which the redox potential acts as a thermodynamic force while the presence of biofilms and the precipitation of metallic particles in areas of high gradients in the redox potential allows the transfer of electrons creating a net source of current in the system. Consequently, organic- rich contaminant plumes in the ground behaves as natural geobatteries creating their own electrical field that can be measured at the ground surface and inverted to retrieve the geometry of the source and to determine the in situ redox potential in a non-intrusive way.

Revil, A.

2006-05-01

72

Wetland Delineation  

NSDL National Science Digital Library

Learning how to delineate a wetland using official criteria can be an enlightening experience for students and teachers. The objective of this investigation is for students to delineate the boundaries of an area in a watershed and categorize it as a wetla

Van Faasen, Carl; Peaslee, Graham; Soukhome, Jennifer; Statema, William

2009-04-01

73

Evolution of radioactive dose rates in fresh sediment deposits along coastal rivers draining Fukushima contamination plume  

PubMed Central

Measurement of radioactive dose rates in fine sediment that has recently deposited on channel bed-sand provides a solution to address the lack of continuous river monitoring in Fukushima Prefecture after Fukushima Dai-ichi nuclear power plant (FDNPP) accident. We show that coastal rivers of Eastern Fukushima Prefecture were rapidly supplied with sediment contaminated by radionuclides originating from inland mountain ranges, and that this contaminated material was partly exported by typhoons to the coastal plains as soon as by November 2011. This export was amplified during snowmelt and typhoons in 2012. In 2013, contamination levels measured in sediment found in the upper parts of the catchments were almost systematically lower than the ones measured in nearby soils, whereas their contamination was higher in the coastal plains. We thereby suggest that storage of contaminated sediment in reservoirs and in coastal sections of the river channels now represents the most crucial issue. PMID:24165695

Evrard, Olivier; Chartin, Caroline; Onda, Yuichi; Patin, Jeremy; Lepage, Hugo; Lefèvre, Irène; Ayrault, Sophie; Ottlé, Catherine; Bonté, Philippe

2013-01-01

74

Evolution of radioactive dose rates in fresh sediment deposits along coastal rivers draining Fukushima contamination plume  

NASA Astrophysics Data System (ADS)

Measurement of radioactive dose rates in fine sediment that has recently deposited on channel bed-sand provides a solution to address the lack of continuous river monitoring in Fukushima Prefecture after Fukushima Dai-ichi nuclear power plant (FDNPP) accident. We show that coastal rivers of Eastern Fukushima Prefecture were rapidly supplied with sediment contaminated by radionuclides originating from inland mountain ranges, and that this contaminated material was partly exported by typhoons to the coastal plains as soon as by November 2011. This export was amplified during snowmelt and typhoons in 2012. In 2013, contamination levels measured in sediment found in the upper parts of the catchments were almost systematically lower than the ones measured in nearby soils, whereas their contamination was higher in the coastal plains. We thereby suggest that storage of contaminated sediment in reservoirs and in coastal sections of the river channels now represents the most crucial issue.

Evrard, Olivier; Chartin, Caroline; Onda, Yuichi; Patin, Jeremy; Lepage, Hugo; Lefèvre, Irène; Ayrault, Sophie; Ottlé, Catherine; Bonté, Philippe

2013-10-01

75

Evolution of radioactive dose rates in fresh sediment deposits along coastal rivers draining Fukushima contamination plume.  

PubMed

Measurement of radioactive dose rates in fine sediment that has recently deposited on channel bed-sand provides a solution to address the lack of continuous river monitoring in Fukushima Prefecture after Fukushima Dai-ichi nuclear power plant (FDNPP) accident. We show that coastal rivers of Eastern Fukushima Prefecture were rapidly supplied with sediment contaminated by radionuclides originating from inland mountain ranges, and that this contaminated material was partly exported by typhoons to the coastal plains as soon as by November 2011. This export was amplified during snowmelt and typhoons in 2012. In 2013, contamination levels measured in sediment found in the upper parts of the catchments were almost systematically lower than the ones measured in nearby soils, whereas their contamination was higher in the coastal plains. We thereby suggest that storage of contaminated sediment in reservoirs and in coastal sections of the river channels now represents the most crucial issue. PMID:24165695

Evrard, Olivier; Chartin, Caroline; Onda, Yuichi; Patin, Jeremy; Lepage, Hugo; Lefèvre, Irène; Ayrault, Sophie; Ottlé, Catherine; Bonté, Philippe

2013-01-01

76

Mercury speciation and mobilization in a wastewater-contaminated groundwater plume.  

PubMed

We measured the concentration and speciation of mercury (Hg) in groundwater down-gradient from the site of wastewater infiltration beds operated by the Massachusetts Military Reservation, western Cape Cod, Massachusetts. Total mercury concentrations in oxic, mildly acidic, uncontaminated groundwater are 0.5-1 pM, and aquifer sediments have 0.5-1 ppb mercury. The plume of impacted groundwater created by the wastewater disposal is still evident, although inputs ceased in 1995, as indicated by anoxia extending at least 3 km down-gradient from the disposal site. Solutes indicative of a progression of anaerobic metabolisms are observed vertically and horizontally within the plume, with elevated nitrate concentrations and nitrate reduction surrounding a region with elevated iron concentrations indicating iron reduction. Mercury concentrations up to 800 pM were observed in shallow groundwater directly under the former infiltration beds, but concentrations decreased with depth and with distance down-gradient. Mercury speciation showed significant connections to the redox and metabolic state of the groundwater, with relatively little methylated Hg within the iron reducing sector of the plume, and dominance of this form within the higher nitrate/ammonium zone. Furthermore, substantial reduction of Hg(II) to Hg(0) within the core of the anoxic zone was observed when iron reduction was evident. These trends not only provide insight into the biogeochemical factors controlling the interplay of Hg species in natural waters, but also support hypotheses that anoxia and eutrophication in groundwater facilitate the mobilization of natural and anthropogenic Hg from watersheds/aquifers, which can be transported down-gradient to freshwaters and the coastal zone. PMID:24187956

Lamborg, Carl H; Kent, Doug B; Swarr, Gretchen J; Munson, Kathleen M; Kading, Tristan; O'Connor, Alison E; Fairchild, Gillian M; Leblanc, Denis R; Wiatrowski, Heather A

2013-12-01

77

Mercury speciation and mobilization in a wastewater-contaminated groundwater plume  

USGS Publications Warehouse

We measured the concentration and speciation of mercury (Hg) in groundwater down-gradient from the site of wastewater infiltration beds operated by the Massachusetts Military Reservation, western Cape Cod, Massachusetts. Total mercury concentrations in oxic, mildly acidic, uncontaminated groundwater are 0.5–1 pM, and aquifer sediments have 0.5–1 ppb mercury. The plume of impacted groundwater created by the wastewater disposal is still evident, although inputs ceased in 1995, as indicated by anoxia extending at least 3 km down-gradient from the disposal site. Solutes indicative of a progression of anaerobic metabolisms are observed vertically and horizontally within the plume, with elevated nitrate concentrations and nitrate reduction surrounding a region with elevated iron concentrations indicating iron reduction. Mercury concentrations up to 800 pM were observed in shallow groundwater directly under the former infiltration beds, but concentrations decreased with depth and with distance down-gradient. Mercury speciation showed significant connections to the redox and metabolic state of the groundwater, with relatively little methylated Hg within the iron reducing sector of the plume, and dominance of this form within the higher nitrate/ammonium zone. Furthermore, substantial reduction of Hg(II) to Hg0 within the core of the anoxic zone was observed when iron reduction was evident. These trends not only provide insight into the biogeochemical factors controlling the interplay of Hg species in natural waters, but also support hypotheses that anoxia and eutrophication in groundwater facilitate the mobilization of natural and anthropogenic Hg from watersheds/aquifers, which can be transported down-gradient to freshwaters and the coastal zone.

Lamborg, Carl H.; Kent, Doug B.; Swarr, Gretchen J.; Munson, Kathleen M.; Kading, Tristan; O'Connor, Alison E.; Fairchild, Gillian M.; LeBlanc, Denis R.; Wiatrowski, Heather A.

2013-01-01

78

Coupling of Realistic Rate Estimates with Genomics for Assessing Contaminant Attenuation and Long-Term Plume Containment  

SciTech Connect

Acceptance of monitored natural attenuation (MNA) as a preferred treatment technology saves significant site restoration costs for DOE. However, in order to be accepted MNA requires direct evidence of which processes are responsible for the contaminant loss and also the rates of the contaminant loss. Our proposal aims to: 1) provide evidence for one example of MNA, namely the disappearance of the dissolved trichloroethylene (TCE) from the Snake River Plain aquifer (SRPA) at the Idaho National Laboratory’s Test Area North (TAN) site, 2) determine the rates at which aquifer microbes can co-metabolize TCE, and 3) determine whether there are other examples of natural attenuation of chlorinated solvents occurring at DOE sites. To this end, our research has several objectives. First, we have conducted studies to characterize the microbial processes that are likely responsible for the co-metabolic destruction of TCE in the aquifer at TAN (University of Idaho and INL). Second, we are investigating realistic rates of TCE co-metabolism at the low catabolic activities typical of microorganisms existing under aquifer conditions (INL). Using the co-metabolism rate parameters derived in low-growth bioreactors, we will complete the models that predict the time until background levels of TCE are attained in the aquifer at TAN and validate the long-term stewardship of this plume. Coupled with the research on low catabolic activities of co-metabolic microbes we are determining the patterns of functional gene expression by these cells, patterns that may be used to diagnose the co-metabolic activity in the SRPA or other aquifers. Third, we have systematically considered the aquifer contaminants at different locations in plumes at other DOE sites in order to determine whether MNA is a broadly applicable remediation strategy for chlorinated hydrocarbons (North Wind Inc.). Realistic terms for co-metabolism of TCE will provide marked improvements in DOE’s ability to predict and monitor natural attenuation of chlorinated organics, increase the acceptability of this solution, and provide significant economic and health benefits through this noninvasive remediation strategy. This project also aims to derive valuable genomic information about the functional attributes of subsurface microbial communities upon which DOE must depend to resolve some of its most difficult contamination issues.

Colwell, F. S.; Crawford, R. L.; Sorenson, K.

2005-09-01

79

Coupling of Realistic Rate Estimates with Genomics for Assessing Contaminant Attenuation and Long-Term Plume Containment - Task 4: Modeling - Final Report  

SciTech Connect

Trichloroethene (TCE), a common groundwater contaminant, can be degraded under certain conditions by microorganisms that occur naturally in the subsurface. TCE can be degraded under anaerobic conditions to less chlorinated compounds and ultimately into the non-chlorinated, non-hazardous end product, ethene, via anaerobic reductive dechlorination (ARD). ARD is widely recognized as a TCE degradation mechanism, and occurs in active groundwater remediation and can occur during monitored natural attenuation (MNA). MNA relies on natural processes, such as dispersion and degradation, to reduce contaminant concentrations to acceptable levels without active human intervention other than monitoring. TCE can also be biodegraded under aerobic conditions via cometabolism, in which microbial enzymes produced for other purposes fortuitously also react with TCE. In cometabolism, TCE is oxidized directly to non-hazardous products. Cometabolism as a TCE-degrading process under aerobic conditions is less well known than ARD. Natural attenuation is often discounted as a TCE remedial alternative in aerobic conditions based on the paradigm that TCE is biodegradable only under anaerobic conditions. In contrast to this paradigm, TCE was shown to degrade relative to conservative co-contaminants at an environmentally significant rate in a large (approximately 3 km long) TCE plume in aerobic groundwater at the Idaho National Laboratory (INL), and the degradation mechanism was shown to be cometabolism. MNA was selected as the remedy for most of this plume, resulting in a considerable cost savings relative to conventional remedial methods. To determine if cometabolism might be a viable remedy at other sites with TCE-contaminated aerobic groundwater, TCE plumes at Department of Energy (DOE) facilities were screened to evaluate whether TCE commonly degrades in aerobic groundwater, and if degradation rates are fast enough that natural attenuation could be a viable remedy. One hundred and twenty seven plumes at 24 DOE facilities were screened, and 14 plumes were selected for detailed examination. In the plumes selected for further study, spatial changes in the concentration of a conservative co-contaminant were used to compensate for the effects of mixing and temporal changes in TCE release from the contaminant source. Decline in TCE concentration along a flow path in excess of the co contaminant concentration decline was attributed to cometabolic degradation. This study indicated that TCE was degraded in 9 of the 14 plumes examined, with first order degradation half-lives ranging from about 1 to 12 years. TCE degradation in about two-thirds of the plumes examined suggests that cometabolism of TCE in aerobic groundwater is a common occurrence, in contrast to the conventional wisdom that TCE is recalcitrant in aerobic groundwater. The degradation half-life values calculated in this study are short enough that natural attenuation may be a viable remedy in many aerobic plumes. Computer modeling of groundwater flow and contaminant transport and degradation is frequently used to predict the evolution of groundwater plumes, and for evaluating natural attenuation and other remedial alternatives. An important aspect of a computer model is the mathematical approach for describing degradation kinetics. A common approach is to assume that degradation occurs as a first-order process. First order kinetics are easily incorporated into transport models and require only a single value (a degradation half-life) to describe reaction kinetics. The use of first order kinetics is justified in many cases because more elaborate kinetic equations often closely approximate first order kinetics under typical field conditions. A previous modeling study successfully simulated the INL TCE plume using first order degradation kinetics. TCE cometabolism is the result of TCE reacting with microbial enzymes that were produced for other purposes, such as oxidizing a growth substrate to obtain energy. Both TCE and the growth substrate compete for enzyme reactive sites, and the presence of

Robert C. Starr

2005-10-31

80

IDENTIFYING AND PREDICTING DIVING PLUME BEHAVIOR AT GROUNDWATER SITES CONTAMINATED WITH MTBE: PART 1  

EPA Science Inventory

In EPA Region 5, MTBE from leaking underground storage tanks (LUST) has contaminated groundwater. In some cases, drinking water supply wells have been impacted, which forced local communities to adopt expensive alternatives. Traditionally, LUST site characterizations have focus...

81

Investigating the source of contaminated plumes downstream of the Alborz Sharghi coal washing plant using EM34 conductivity data, VLF-EM and DC-resistivity geophysical methods  

NASA Astrophysics Data System (ADS)

Coal washing factories may create serious environmental problems due to pyrite oxidation and acid mine drainage generation from coal waste piles on nearby land. Infiltration of pyrite oxidation products through the porous materials of the coal waste pile by rainwater cause changes in the conductivity of underground materials and groundwater downstream of the pile. Electromagnetic and electrical methods are effective for investigation and monitoring of the contaminated plumes caused by coal waste piles and tailings impoundments. In order to investigate the environmental impact from a coal waste pile at the Alborz Sharghi coal washing plant, an EM34 ground conductivity meter was used on seven parallel lines in an E-W direction, downstream of the waste pile. Two-dimensional resistivity models obtained by the inversion of EM34 conductivity data identified conductive leachate plumes. In addition, quasi-3D inversion of EM34 data has confirmed the decreasing resistivity at depth due to the contaminated plumes. Comparison between EM34, VLF and DC-resistivity datasets, which were acquired for similar survey lines, agree well in identifying changes in the resistivity trend. The EM34 and DC-resistivity sections have greater similarity and better smoothness rather than those of the VLF model. Two-dimensional inversion models of these methods have shown some contaminated plumes with low resistivity.

Shiraz, Farzin Amirkhani; Ardejani, Faramarz Doulati; Moradzadeh, Ali; Arab-Amiri, Ali Reza

2013-01-01

82

Amplitude Variation With Offset (AVO) Analysis of Ground Penetrating Radar Data for Direct Detection and Delineation of NAPL Contamination  

NASA Astrophysics Data System (ADS)

Amplitude and phase variation with offset analysis of ground penetrating radar data (APVO/GPR) can improve the differentiation of non-aqueous phase liquid (NAPL) from stratigraphic changes. Previous controlled experiments have shown that common offset (CO) GPR methods can detect the presence of NAPL in soil by examining amplitude and travel time (velocity) anomalies. Unfortunately, stratigraphic changes such as the presence of a silt or clay lens or perched water table may produce similar amplitude and velocity anomalies. Therefore, it is difficult to delineate NAPL in a terrain with unknown stratigraphy exclusively using CO data collection methods. Forward models based on the Fresnel equations predict that amplitude responses exist at various incidence angles that will allow for differentiating NAPL from hydrogeologic changes. Models generated as part of this study indicate that analyzing the difference in amplitude responses from linearly polarized electric field vertically oriented (EV) to the horizontally oriented (EH) signals at various incidence angles improves target discrimination. A case history is presented demonstrating that collecting common-midpoint (CMP) GPR data using EH and EV polarized signals at anomalous CO amplitude responses and analyzing the data using APVO and normalized residual polarization (NRP) methods can improve the detection and differentiation of NAPL from stratigraphic changes in the subsurface. These results are corroborated using a capacitively coupled resisitivity instrument and subsequent intrusive sampling.

Jordan, T. E.; Baker, G. S.

2003-12-01

83

Compound-specific carbon isotope analysis of a contaminant plume in Kingsford, Michigan, USA  

USGS Publications Warehouse

Compound-specific isotope analysis was used to study a contaminated site near Kingsford, Michigan, USA. Organic compounds at three of the sites studied had similar ??13C values indicating that the contaminant source is the same for all sites. At a fourth site, chemical and ??13C values had evolved due to microbial degradation of organics, with the ??13C being much heavier than the starting materials. A microcosm experiment was run to observe isotopic changes with time in the methane evolved and in compounds remaining in the water during degradation. The ??13C values of the methane became heavier during the initial period of the run when volatile fatty acids were being consumed. There was an abrupt decrease in the ??13C values when fatty acids had been consumed and phenols began to be utilized. The ??13C value of the propionate remaining in solution also increased, similar to the results found in the field.

Michel, R.L.; Silva, S.R.; Bemis, B.; Godsy, E.M.; Warren, E.

2001-01-01

84

Assessing contaminant-removal conditions and plume persistence through analysis of data from long-term pump-and-treat operations.  

PubMed

Historical groundwater-withdrawal and contaminant-concentration data collected from long-term pump-and-treat operations were analyzed and used to examine contaminant mass discharge (CMD) and mass-removal behavior for multiple sites. Differences in behavior were observed, and these differences were consistent with the nature of contaminant distributions and subsurface properties of the sites. For example, while CMD exhibited a relatively rapid decline during the initial stage of operation for all three sites, the rate of decline varied. The greatest rate was observed for the PGN site, whereas the lowest rate was observed for the MOT site. In addition, the MOT site exhibited the lowest relative reduction in CMD. These results are consistent with the actuality that the MOT site likely contains the greatest proportion of poorly accessible contaminant mass, given that it comprises a combined alluvium and fractured-bedrock system in which solvent and dissolved mass are present directly in the bedrock. The relative contributions of the source zones versus the plumes to total CMD were determined. Constrained contaminant mass removal was observed to influence the plumes for all three sites, and was attributed to a combination of uncontrolled (or imperfectly controlled) sources, back diffusion, and well-field hydraulics. The results presented herein illustrate that detailed analysis of operational pump-and-treat data can be a cost-effective method for providing value-added characterization of contaminated sites. PMID:24914523

Brusseau, Mark L; Guo, Zhilin

2014-08-01

85

Coupling of Realistic Rate Estimates with Genomics for Assessing Contaminant Attenuation and Long-Term Plume Containment  

SciTech Connect

Acceptance of monitored natural attenuation (MNA) as a preferred treatment technology saves significant site restoration costs for DOE. However, in order to be accepted MNA requires direct evidence of which processes are responsible for the contaminant loss and also the rates of the contaminant loss. Our proposal aims to: 1) provide evidence for one example of MNA, namely the disappearance of the dissolved trichloroethylene (TCE) from the Snake River Plain aquifer (SRPA) at the Idaho National Laboratory’s Test Area North (TAN) site, 2) determine the rates at which aquifer microbes can co-metabolize TCE, and 3) determine whether there are other examples of natural attenuation of chlorinated solvents occurring at DOE sites. To this end, our research has several objectives. First, we have conducted studies to characterize the microbial processes that are likely responsible for the co-metabolic destruction of TCE in the aquifer at TAN (University of Idaho and INL). Second, we are investigating realistic rates of TCE co-metabolism at the low catabolic activities typical of microorganisms existing under aquifer conditions (INL). Using the co-metabolism rate parameters derived in low-growth bioreactors, we will complete the models that predict the time until background levels of TCE are attained in the aquifer at TAN and validate the long-term stewardship of this plume. Coupled with the research on low catabolic activities of co-metabolic microbes we are determining the patterns of functional gene expression by these cells, patterns that may be used to diagnose the co-metabolic activity in the SRPA or other aquifers.

Colwell, F.S.; Crawford, R.L.; Sorenson, K.

2005-09-01

86

Surface and borehole electromagnetic imaging of conducting contaminant plumes. 1998 annual progress report  

SciTech Connect

'Electromagnetic induction tomography is a promising new tool for imaging electrical conductivity variations in the earth. The source field is a magnetic field generated by currents in wire coils. This source field is normally produced in one borehole, while the received signals are the measured small changes in magnetic field in another, distant borehole; however, the method may also be used successfully in combination with surface sources and receivers. The goal of this procedure is to image electrical conductivity variations in the earth, much as x-ray tomography is used to image density variations through cross-sections of the body. Although field techniques have been developed and applied to collection of such EM data, the algorithms for inverting the magnetic data to produce the desired images of electrical conductivity have not kept pace. The current state of the art in electromagnetic data inversion is based on the Born/Rytov approximation (requiring a low contrast assumption), or extensions. However, it is known that conductivity variations in fact range over several orders of magnitude and therefore require nonlinear analysis. The goal of this project is therefore to join theory and experiment to produce enhanced images of electrically conducting fluids underground, allowing better localization of contaminants and improved planning strategies for the subsequent remediation efforts.'

Berryman, J.G.

1998-06-01

87

Surface and borehole electromagnetic imaging of conducting contaminant plumes. 1997 annual progress report  

SciTech Connect

'Electromagnetic induction tomography is a promising new tool for imaging electrical conductivity variations in the earth. The EM source field is produced by induction coil (magnetic dipole) transmitters deployed at the surface or in boreholes. Vertical and horizontal component magnetic field detectors are deployed in other boreholes or on the surface. Sources and receivers are typically deployed in a configuration surrounding the region of interest. The goal of this procedure is to image electrical conductivity variations in the earth, much as x-ray tomography is used to image density variations through cross-sections of the body. Although such EM field techniques have been developed and applied, the algorithms for inverting the magnetic data to produce the desired images of electrical conductivity have not kept pace. One of the main reasons for the lag in the algorithm development has been the fact that the magnetic induction problem is inherently three dimensional: other imaging methods such as x-ray and seismic can make use of two-dimensional approximations that are not too far from reality, but the author does not have this luxury in EM induction tomography. In addition, previous field experiments were conducted at controlled test sites that typically do not have much external noise or extensive surface clutter problems often associated with environmental sites. To use the same field techniques in environments more typical of cleanup sites requires a new set of data processing tools to remove the effects of both noise and clutter. The goal of this project is to join theory and experiment to produce enhanced images of electrically conducting fluids underground, allowing better localization of contaminants and improved planning strategies for the subsequent remediation efforts. After explaining the physical context in more detail, this report will summarize the progress made in the first year of this project: (1) on code development and (2) on field tests of these methods. The author concludes with a brief statement of the research directions for the second year of the project.'

Berryman, J.G.

1997-01-01

88

Plume Busters  

NSDL National Science Digital Library

This is an interactive simulator in which students take on the role of an environmental consultant to solve a contamination problem (genrally in the Buffalo River valley alluvial aquifer). Students apply ground-water principles to solve a simulated contamination problem. They calculate the average ground-water velocity from the aquifer porosity and the specific discharge, which in turn is calculated from the aquifer hydraulic conductivity and the hydraulic gradient using Darcy's law. The distances traveled away from the spill site by the edges of the plume are calculated from the average ground-water velocity and time since contaminants first and last entered the aquifer. Students use either production wells or a production/injection well couplet placed appropriately with respect to the moving plume. They design the wellfield and need only a qualitative understanding of well hydraulics including the fundamental concepts of cone of depression, cone of impression, capture zone, and zone of influence. Grade 11-12, undergraduate non-hydrogeology major, and undergraduate hydrogeology major versions of the software are currently available.

Macfarlane, P.; Bohling, Geoffrey

89

3-D spectral IP imaging: Non-invasive characterization of contaminant plumes. Annual progress report, September 15, 1996--September 14, 1997  

SciTech Connect

'The objective of this project is to develop the scientific basis for characterizing contaminant plumes in the earth''s subsurface using field measurements of induced polarization (IP) effects. The first-year accomplishments are (1) laboratory experiments on fluid-saturated sandstones quantifying the dependence of spectral IP responses on solution chemistry and rock micro-geometry; (2) library research on the current understanding of electromagnetic coupling effects on IP data acquired in the field: and (3) development of prototype forward modeling and inversion algorithms for interpreting IP data in terms of 3-D models of complex resistivity.'

Frye, K.M.; Lesmes, D.P.; Morgan, F.D.; Rodi, W.; Shi, W.; Sturrock, J.

1997-12-01

90

The Impact of In-situ Chemical Oxidation on Contaminant Mass Discharge: Linking Source-Zone and Plume-Scale Characterizations of Remediation Performance  

PubMed Central

A large-scale permanganate-based in-situ chemical oxidation (ISCO) effort has been conducted over the past ten years at a federal Superfund site in Tucson, AZ, for which trichloroethene (TCE) is the primary contaminant of concern. Remediation performance was assessed by examining the impact of treatment on contaminant mass discharge, an approach that has been used for only a very few prior ISCO projects. Contaminant mass discharge tests were conducted before and after permanganate injection to measure the impact at the source-zone scale. The results indicate that ISCO caused a significant reduction in mass discharge (approximately 75%). The standard approach of characterizing discharge at the source-zone scale was supplemented with additional characterization at the plume scale, which was evaluated by examining the change in contaminant mass discharge associated with the pump-and-treat system. The integrated contaminant mass discharge decreased by approximately 70%, consistent with the source-zone-scale measurements. The integrated mass discharge rebounded from 0.1 to 0.2 Kg/d within one year after cessation of permanganate injections, after which it has been stable for several years. Collection of the integrated contaminant mass discharge data throughout the ISCO treatment period provided a high-resolution, real-time analysis of the site-wide impact of ISCO, thereby linking source-zone remediation to impacts on overall risk. The results indicate that ISCO was successful in reducing contaminant mass discharge at this site, which comprises a highly heterogeneous subsurface environment. Analysis of TCE sediment concentration data for core material collected before and after ISCO supports the hypothesis that the remaining mass discharge is associated in part with poorly-accessible contaminant mass residing within lower-permeability zones. PMID:21615133

Brusseau, M.L.; Carroll, K.C.; Allen, T.; Baker, J.; DiGuiseppi, W.; Hatton, J.; Morrison, C.; Russo, A.; Berkompas, J.

2011-01-01

91

Three-dimensional analysis of future groundwater flow conditions and contaminant plume transport in the Hanford Site unconfined aquifer system: FY 1996 and 1997 status report  

SciTech Connect

A three-dimensional numerical model of groundwater flow and transport, based on the Coupled Fluid Energy, and Solute Transport (CFEST) code, was developed for the Hanford Site to support the Hanford Groundwater Project (HGWP), managed by Pacific Northwest National Laboratory. The model was developed to increase the understanding and better forecast the migration of several contaminant plumes being monitored by the HGWP, and to support the Hanford Site Composite Analysis for low-level waste disposal in the 200-Area Plateau. Recent modeling efforts have focused on continued refinement of an initial version of the three-dimensional model developed in 1995 and its application to simulate future transport of selected contaminant plumes in the aquifer system. This version of the model was updated using a more current version of the CFEST code called CFEST96. Prior to conducting simulations of contaminant transport with the three-dimensional model, a previous steady-state, two-dimensional model of the unconfined aquifer system was recalibrated to 1979 water-table conditions with a statistical inverse method implemented in the CFEST-INV computer code. The results of the recalibration were used to refine the three-dimensional conceptual model and to calibrate it with a conceptualization that preserves the two-dimensional hydraulic properties and knowledge of the aquifer`s three-dimensional properties for the same 1979 water-table conditions. The transient behavior of the three-dimensional flow model was also calibrated by adjusting model storage properties (specific yield) until transient water-table predictions approximated observed water-table elevations between 1979 and 1996.

Cole, C.R.; Wurstner, S.K.; Williams, M.D.; Thorne, P.D.; Bergeron, M.P.

1997-12-01

92

Draft Genome Sequence of Acinetobacter oleivorans PF1, a Diesel-Degrading and Plant-Growth-Promoting Endophytic Strain Isolated from Poplar Trees Growing on a Diesel-Contaminated Plume.  

PubMed

We report the 3.7-Mb draft genome of Acinetobacter oleivorans strain PF1, a hydrocarbonoclastic Gram-negative bacterium in the class Gammaproteobacteria, isolated from poplar trees growing on a diesel-contaminated plume at the Ford Motor Company site in Genk, Belgium. Strain PF1 is a potent plant-growth promoter, useful for diesel fuel phytoremediation applications. PMID:25657268

Gkorezis, Panagiotis; Rineau, Francois; Van Hamme, Jonathan; Franzetti, Andrea; Daghio, Matteo; Thijs, Sofie; Weyens, Nele; Vangronsveld, Jaco

2015-01-01

93

Assessment of diesel contamination in groundwater using electromagnetic induction geophysical techniques  

SciTech Connect

Determining hydrocarbon plumes in groundwater is typically accomplished through the installation of extensive monitoring wells. Issues of scale and site heterogeneities tend to introduce errors in delineating the extent of contamination and environmental impact. In this study, electromagnetic induction survey was investigated as an alternative technique for mapping petroleum contaminants in the subsurface. The surveys were conducted at a coal mining site near Gillette, Wyoming, using the EM34-XL ground conductivity meter. Data from this survey were validated with known concentrations of diesel compounds detected in groundwater from the study site. Groundwater data correlated well with the electromagnetic survey data, which was used to generate a site model to identify subsurface diesel plumes. To our knowledge, this is one of the first studies to use electromagnetic survey techniques for mapping hydrocarbon contamination in groundwater. Results from this study indicate that this geophysical technique can be an effective tool for assessing subsurface petroleum hydrocarbon sources and plumes at contaminated sites.

Jin, S.; Fallgren, P.; Cooper, J.; Morris, J; . Urynowicz, M. [Western Research Institute, Laramie, WY (United States)

2008-07-01

94

Investigation of the potential source area, contamination pathway, and probable release history of chlorinated-solvent-contaminated groundwater at the Capital City Plume Site, Montgomery, Alabama, 2008-2010  

USGS Publications Warehouse

Detection of the organic solvent perchloroethylene (PCE) in a shallow public-supply well in 1991 and exposure of workers in 1993 to solvent vapors during excavation activities to depths near the water table provided evidence that the shallow aquifer beneath the capital city of Montgomery, Alabama, was contaminated. Investigations conducted from 1993 to 1999 by State and Federal agencies confirmed the detection of PCE in the shallow aquifer, as well as the detection of the organic solvent trichloroethylene (TCE) and various inorganic compounds, but the source of the groundwater contamination was not determined. In May 2000 the U.S. Environmental Protection Agency proposed that the site, called the Capital City Plume (CCP) Site, be a candidate for the National Priorities List. Between 2000 and 2007, numerous site-investigation activities also did not determine the source of the groundwater contamination. In 2008, additional assessments were conducted at the CCP Site to investigate the potential source area, contamination pathway, and the probable release history of the chlorinated-solvent-contaminated groundwater. The assessments included the collection of (1) pore water in 2008 from the hyporheic zone of a creek using passive-diffusion bag samplers; (2) tissue samples in 2008 and 2009 from trees growing in areas of downtown Montgomery characterized by groundwater contamination and from trees growing in riparian zones along the Alabama River and Cypress Creek; and (3) groundwater samples in 2009 and 2010. The data collected were used to investigate the potential source area of contaminants detected in groundwater, the pathway of groundwater contamination, and constraints on the probable contaminant-release history. The data collected between 2008 and 2010 indicate that the PCE and TCE contamination of the shallow aquifer beneath the CCP Site most likely resulted from the past use and disposal of industrial wastewater from printing operations containing chlorinated solvents into the sanitary sewer and (or) stormwater systems of Montgomery. Moreover, chlorinated-solvent use and disposal occurred at least between the 1940s and 1970s at several locations occupied by printing operations. The data also indicate that PCE and TCE contamination continues to occur in the shallow subsurface near potential release areas and that PCE and TCE have been transported to the intermediate part of the shallow aquifer.

Landmeyer, James E.; Miller, Scott; Campbell, Bruce G.; Vroblesky, Don A.; Gill, Amy C.; Clark, Athena P.

2011-01-01

95

The Development of the Contaminant Exceedance Rating System (CERS) for Comparing Groundwater Contaminant Data.  

E-print Network

?? The typical approach to mapping groundwater contaminant plumes involves drawing plume contours out to each contaminant’s site-specific cleanup criterion. Cleanup criteria differ between contaminants,… (more)

Mierzwiak, Sara M.

2012-01-01

96

An integrated approach for addressing uncertainty in the delineation of groundwater management areas.  

PubMed

Uncertainty is a pervasive but often poorly understood factor in the delineation of wellhead protection areas (WHPAs), which can discourage water managers and practitioners from relying on model results. To make uncertainty more understandable and thereby remove a barrier to the acceptance of models in the WHPA context, we present a simple approach for dealing with uncertainty. The approach considers two spatial scales for representing uncertainty: local and global. At the local scale, uncertainties are assumed to be due to heterogeneities, and a capture zone is expressed in terms of a capture probability plume. At the global scale, uncertainties are expressed through scenario analysis, using a limited number of physically realistic scenarios. The two scales are integrated by using the precautionary principle to merge the individual capture probability plumes corresponding to the different scenarios. The approach applies to both wellhead protection and the mitigation of contaminated aquifers, or in general, to groundwater management areas. An example relates to the WHPA for a supply well located in a complex glacial aquifer system in southwestern Ontario, where we focus on uncertainty due to the spatial distributions of recharge. While different recharge scenarios calibrate equally well to the same data, they result in different capture probability plumes. Using the precautionary approach, the different plumes are merged into two types of maps delineating groundwater management areas for either wellhead protection or aquifer mitigation. The study shows that calibrations may be non-unique, and that finding a "best" model on the basis of the calibration fit may not be possible. PMID:23507137

Sousa, Marcelo R; Frind, Emil O; Rudolph, David L

2013-05-01

97

USE OF AROMATIC ACIDS AND PHOSPHOLIPID-ESTER-LINKED FATTY ACIDS FOR DELINEATION OF PROCESSES AFFECTING AN AQUIFER CONTAMINATED WITH JP-4 FUEL  

EPA Science Inventory

A glacio-fluvial aquifer located at Wurtsmith Air Force Base, Michigan, has been contaminated with JP-4 fuel hydrocarbons released by the crash of a tanker aircraft in October of 1988. A comprehensive analysis of the inorganic and organic geochemical constituents and geomicrobio...

98

Y-12 Groundwater Protection Program Extent Of The Primary Groundwater Contaminants At The Y-12 National Security Complex  

SciTech Connect

This report presents data summary tables and maps used to define and illustrate the approximate lateral extent of groundwater contamination at the U.S. Department of Energy (DOE) Y-12 National Security Complex (Y-12) in Oak Ridge, Tennessee. The data tables and maps address the primary (i.e., most widespread and mobile) organic, inorganic, and radiological contaminants in the groundwater. The sampling locations, calculated contaminant concentrations, plume boundary values, and paired map format used to define, quantify, delineate, and illustrate the approximate extent of the primary organic, inorganic, and radiological contaminants in groundwater at Y-12 are described.

none,

2013-12-01

99

Delineation of a wellhead protection zone and determination of flowpaths from potential groundwater contaminant source areas at Camp Ripley, Little Falls, Minnesota.  

SciTech Connect

Groundwater at Camp Ripley, Minnesota, is recharged both on post and off site and discharged to rivers, wetlands, and pumping wells. The subsurface geologic materials have a wide range of permeabilities and are arranged in a complex fashion as a result of the region's multiple glacial advances. Correlation of individual glacial geologic units is difficult, even between nearby boreholes, because of the heterogeneities in the subsurface. This report documents the creation of a numerical model of groundwater flow for Camp Ripley and hydrologically related areas to the west and southwest. The model relies on a hydrogeological conceptual model built on the findings of a University of Minnesota-Duluth drilling and sampling program conducted in 2001. Because of the site's stratigraphic complexity, a geostatistical approach was taken to handle the uncertainty of the subsurface correlation. The U.S. Geological Survey's MODFLOW code was used to create the steady-state model, which includes input data from a variety of sources and is calibrated to water levels in monitoring wells across much of the site. This model was used for several applications. Wellhead protection zones were delineated for on-site production wells H, L, and N. The zones were determined on the basis of a probabilistic assessment of the groundwater captured by these wells; the assessment, in turn, had been based on multiple realizations of the study area's stratigraphy and groundwater flowfield. An additional application of the model was for estimating flowpaths and times of travel for groundwater at Camp Ripley's range areas and waste management facilities.

Quinn, J. J.; Environmental Science Division

2006-12-22

100

Volatile halocarbons as tracers of pulp mill effluent plumes  

SciTech Connect

This work describes the use of volatile halocarbons in a pulp mill effluent, including chloroform, bromodichloromethane, and tri- and tetrachloroethylene, as tracers for the distribution and movements of effluent currents in a receiving water bay (Jackfish Bay) on the northern shore of Lake Superior. The results indicate the simplicity and usefulness of the technique and the significantly improved resolution of effluent plume delineation over the customary use of conductance profiles. Concentration patterns of the effluent volatiles suggest counterclockwise circulation of bay water that mixes with inflowing lake water at the eastern reach of the outer bay. The distribution of volatile contaminants is governed by the thermal regime of the receiving waters. During the summer months, the effluent plume wedges between the thermocline and epilimnion, mixing into the surface waters as the distance from the input source increases. In the fall, the colder effluent plume sinks into the hypolimnion and is confined by a bay/lake water-density gradient. In the specific case at hand, the distribution patterns of chloroform and a brominated analog, bromodichloromethane, also suggest the release of chloroform from sediments in the bay.

Comba, M.E.; Palabrica, V.S.; Kaiser, K.L.E. (National Water Research Inst., Burlington, Ontario (Canada). Lakes Research Branch)

1994-07-01

101

Phytoscreening for chlorinated solvents using rapid in vitro SPME sampling: Application to urban plume in Verl, Germany  

USGS Publications Warehouse

Rapid detection and delineation of contaminants in urban settings is critically important in protecting human health. Cores from trees growing above a plume of contaminated groundwater in Verl, Germany, were collected in 1 day, with subsequent analysis and plume mapping completed over several days. Solid-phase microextraction (SPME) analysis was applied to detect tetrachloroethene (PCE) and trichloroethene (TCE) to below nanogram/liter levels in the transpiration stream of the trees. The tree core concentrations showed a clear areal correlation to the distribution of PCE and TCE in the groundwater. Concentrations in tree cores were lower than the underlying groundwater, as anticipated; however, the tree core water retained the PCE:TCE signature of the underlying groundwater in the urban, populated area. The PCE:TCE ratio can indicate areas of differing degradation activity. Therefore, the phytoscreening analysis was capable not only of mapping the spatial distribution of groundwater contamination but also of delineating zones of potentially differing contaminant sources and degradation. The simplicity of tree coring and the ability to collect a large number of samples in a day with minimal disruption or property damage in the urban setting demonstrates that phytoscreening can be a powerful tool for gaining reconnaissance-level information on groundwater contaminated by chlorinated solvents. The use of SPME decreases the detection level considerably and increases the sensitivity of phytoscreening as an assessment, monitoring, and phytoforensic tool. With rapid, inexpensive, and noninvasive methods of detecting and delineating contaminants underlying homes, as in this case, human health can be better protected through screening of broader areas and with far faster response times. ?? 2011 American Chemical Society.

Limmer, M.A.; Balouet, J.-C.; Karg, F.; Vroblesky, D.A.; Burken, J.G.

2011-01-01

102

Integrated characterisation of aquifer heterogeneity and landfill leachate plume migration  

NASA Astrophysics Data System (ADS)

The understanding of groundwater flow and contaminant migration is based on our ability to characterize aquifers and represent these processes with numerical simulators. This understanding is required to efficiently remediate contaminated sites since the failure of remediation actions are often related to an insufficient understanding of aquifer heterogeneity. During the last decades, continuous development of numerical simulators allowed models to better represent complex flow systems. However, conventional hydrogeological characterization methods do not provide the data required to define aquifer heterogeneity. An original hydrogeological characterization approach was used to define aquifer heterogeneity and delineate landfill leachate plumes through the use and integration of varied techniques. The objective of the study is to develop a methodology to integrate hydrogeological, geophysical and geochemical data using geostatistical tools. The characterization program aims to better characterize the aquifer, delineate leachate plumes emitted by a former landfill, and guide a study of the natural attenuation of the plumes. The initial phase of the integrated multidisciplinary aquifer characterization program was carried out in a 12 km2 area of the sub-watershed surrounding the landfill of St-Lambert-de-Lauzon, Québec. In the study area, a 10-m thick sandy unconfined aquifer overlies clayey silt and till layers. In this relatively flat area, natural streams as well as agricultural and forestry drainage networks control groundwater flow. The first phase of the project focused on a regional hydrogeological and geochemical characterization where 5 field methods were combined: 1) surface geophysics (ground penetrating radar and electrical tomography) (GPR); 2) direct-push methods including a) cone penetration tests (CPT), b) soil sampling and c) installation of full- screened observation wells; 3) multilevel measurement of geochemical parameters and groundwater sampling with packers; 4) borehole geophysical logging; 5) high resolution hydraulic tests. The different types of data were integrated with multivariate geostatistical analysis and the results showed complex aquifer conditions. The aquifer base exhibits large topographic variations and semi-confined conditions seem to be present in certain locations. These conditions have a significant influence on groundwater flow and leachate migration. The geostatistical interpretation of multilevel geochemical parameters, combined with CPT data, provides a definition of groundwater geochemical spatial variability and indicates the likely extent of landfill leachate. This detailed knowledge of the aquifer serves as a base for the initial development of a numerical model considering heterogeneity and guides further characterization of the aquifer and plume. Keywords: characterization, heterogeneity, direct push, surface geophysics, numerical model, landfill leachate, natural attenuation.

Tremblay, L.; Lefebvre, R.; Gloaguen, E.; Paradis, D.

2009-05-01

103

Challenge in Flow Path Delineation and Modification: SECUREarth Initiative  

NASA Astrophysics Data System (ADS)

After decades of studies, our knowledge about subsurface flow paths has large uncertainty and our capability to enhance or reduce formation permeability is inefficient and rudimentary. This is the case for fossil energy production, in environment remediation, in greenhouse gas sequestration, in nuclear waste disposal, in geothermal heat extraction, and in groundwater management. Fluid imaging, in addition to rock structure imaging, is needed to enhance petroleum extraction, to isolate contaminant plumes, and to prevent leakage from storage reservoirs. Flow focusing from surface to depth must be quantified to determine the flow path magnitude and spacing in order to determine the degrees of dissolution and transport of emplaced wastes. These diverse problems have common goals: either to isolate or to enhance subsurface fluid movement. It is crucial to identify the common features from different problems and refocus our efforts to delineate and then to manipulate flow paths. Geochemical engineering and geomicrobiological engineering need to combine laboratory studies, field experiments, and modeling approaches to verify and validate our understanding and to design solutions. An initiative SECUREarth is being developed to rally the scientists and engineers from national laboratories, universities, and industry to address key critical bottlenecks that prevent significant progress in solving common subsurface issues. SECUREarth is aimed to develop cross-cutting, multi-disciplinary approaches for solving urgent energy and environment problems in the earth, in order to achieve quantum leaps and breakthroughs in earth science and technology.

Bodvarsson, G. S.; Majer, E. L.; Wang, J. S.; Colwell, F.; Redden, G.

2005-12-01

104

Groundwater Contamination  

NSDL National Science Digital Library

This site by the Michigan Environmental Education Curriculum presents an interactive module that provides an introduction to groundwater quality issues. The information is presented as a series of slides with text, animations, quiz questions and interactive features. Topics include types of aquifers, groundwater movement, sources of contamination, the concentration and dispersion of contaminants, plumes and remediation.

Matthew Babcock

105

Finiteness of steady state plumes  

Microsoft Academic Search

The finite maximum length of a steady state contaminant plume is determined by developing and employing a new analytical solution which overcomes two drawbacks associated with existing approaches. First, we account for a sharp front caused by the complete consumption of the pollutant (“electron donor”) and some electron acceptor in an instantaneous binary reaction occurring at the front. This approach

Rudolf Liedl; Albert J. Valocchi; Peter Dietrich; Peter Grathwohl

2005-01-01

106

Basic Research in Electric Propulsion. Part I: Pulsed Plasma Thruster Propellant Efficiency and Contamination. Part II: Arcjet Remote Plume Measurement and Hydrogen Density  

NASA Astrophysics Data System (ADS)

Pulsed Plasma Thrusters (PPT) have been the major technology under investigation for the Small Satellite Electric Propulsion Thruster Research program. Arcjet technology is also under investigation with Electric Propulsion Space Experiment Optical Signature experiments underway and Multiphoton Laser Induced Fluorescence Measurements of Ground State Atomic Hydrogen have been performed in an arcjet plume. At present PPTs are being tested in the laboratory environment with investigations under way to determine exact inefficiency mechanisms that can be corrected. This work has already identified previously unknown physical behavior in the PPT. The Electric Propulsion Space Experiment is a flight demonstration of a 30 kW ammonia arcjet propulsion system. Optical measurements of the arcjet plume were performed using on-board optical equipment ground observatories and other space platforms. Low power arcjet technology provided definitive work on atomic species plume concentrations in low power hydrogen arcjet plumes. This work applied a flame diagnostic Multiphoton Laser Induced Fluorescence to the excited-state plasma environment to investigate concentration levels of atomic ground-state hydrogen.

Pobst, J. A.; Spanjers, G. G.; Wysong, I. J.; Malak, J. B.

2002-02-01

107

Anatomy of a Pathological Mantle Plume  

NASA Astrophysics Data System (ADS)

Our understanding of the Galapagos mantle plume has evolved over the past 15 years, largely as a result of the integration of geochemical and geophysical studies carried out at increasingly detailed spatial scales. Pioneering isotopic studies by Bill White and his colleagues revealed that enriched material was concentrated on the north, west, and south edges of the archipelago in an east-facing horseshoe. This, coupled with consideration of novel fluid dynamic models, resulted in the bent plume hypothesis (White et al., 1993), in which the relatively weak Galapagos plume is tilted in the direction of plate motion by shear forces generated by the movement of the overlying plate. The drag of the plate was thought to cause progressive entrainment of the upper mantle as the plume spread to the east. Subsequent sampling of seamounts on the Galapagos platform complicated our understanding of the plume, and indicated that the northern Galapagos Islands and seamounts could not be incorporated into the bent plume model. Instead, this area is best explained as a distinct province from the main archipelago, whose origin primarily results from the flow of material from the plume toward the Galapagos Spreading Center. Furthermore, the northern margin of the plume is defined by Wolf volcano, where the lithospheric cap controls melting conditions. The southern edge of the plume is characterized by rejuvenescent volcanism at Floreana Island. This activity has been attributed to metasomatized rocks in the plume that are only detectable where melting is limited to shallow mantle depths at the cooler margin of the plume. Xenoliths from Floreana indicate that it formerly had the isotopic signature of the western Galapagos. Several lines of evidence point to the plume center being located near Fernandina volcano, including high 3He/4He signals observed in both subaerial and submarine lavas from Fernandina and seismic tomographic studies. These seismic studies delineate the ascending Galapagos plume and how it spreads as it impacts the bottom of the lithosphere. The Galapagos plume is notable for its high Nb/La and superchondritic Nb/Ta. We attribute these features to recycled rutile-bearing eclogites in the Galapagos plume.

Harpp, K. S.; Geist, D. J.

2008-12-01

108

Space Shuttle Plume and Plume Impingement Study  

NASA Technical Reports Server (NTRS)

The extent of the influence of the propulsion system exhaust plumes on the vehicle performance and control characteristics is a complex function of vehicle geometry, propulsion system geometry, engine operating conditions and vehicle flight trajectory were investigated. Analytical support of the plume technology test program was directed at the two latter problem areas: (1) definition of the full-scale exhaust plume characteristics, (2) application of appropriate similarity parameters; and (3) analysis of wind tunnel test data. Verification of the two-phase plume and plume impingement models was directed toward the definition of the full-scale exhaust plume characteristics and the separation motor impingement problem.

Tevepaugh, J. A.; Penny, M. M.

1977-01-01

109

Assessment of groundwater contamination at Wurtsmith Air Force Base, Michigan, 1982-85  

SciTech Connect

The Arrow Street purge system, installed in 1982 to remove contaminants from the Building 43 plume, has lowered concentrations of trichloroethylene (TCE) in groundwater in the central part of the most contaminated area from a range of 1,000 to 2,000 microg/L to about 200 microg/L. TCE is not escaping off-Base from this area. In the southern part of the Base a plume containing principally TCE and dichloroethylene (DCE) has been delineated along Mission Drive Maximum concentrations observed were 3,290 microg/L of TCE and 1,480 microg/L of DCE. Hydrologically suitable sites for purge wells were identified in the southern part of the plume using a new ground-water flow model of the Base. A benzene plume near the bulk-fuel storage area has shifted to a more northerly direction under influence of the Arrow Street purge system. It is thought to originate from a spill that occurred several years ago. In general, concentrations found in water do not different greatly from those observed in 1981. Since 1981, concentrations of TCE have decreased significantly in the Alert Apron plume. Near the origin of the plume, the concentration of TCE has decreased from 1,000 microg/L in 1980 to 50 microg/L in 1984. Water from Van Etten Lake near the termination of the plume had only a trace of TCE at one site. Benzene detected in water from well AF2 seems to originate near the former site of buried fuel tanks west of the operational apron. During periods of normal purge pumping along Arrow Street, contaminants and drawn toward water-supply wells AF2, AF4, and AF5. 10 refs., 55 figs., 16 tabs.

Cummings, T.R.; Twenter, F.R.

1986-01-01

110

Assessment of ground-water contamination at Wurtsmith Air Force Base, Michigan, 1982-85  

USGS Publications Warehouse

Study of ground-water contamination at Wurtsmith Air Force Base, Michigan, defined the movement and distribution of volatile organic compounds in the glacial sand and gravel aquifer at known sites of contamination, and has defined new plumes at two other sites. The Arrow Street purge system, installed in 1982 to remove contaminants from the Building 43 plume, has lowered concentrations of trichloroethylene (TCE) in groundwater in the central part of the most contaminated area from a range of 1,000 to 2,000 microg/L to about 200 microg/L. TCE is not escaping off-Base from this area. In the southern part of the Base a plume containing principally TCE and dichloroethylene (DCE) has been delineated along Mission Drive. Maximum concentrations observed were 3,290 microg/L of TCE and 1,480 microg/L of DCE. Hydrologically suitable sites for purge wells were identified in the southern part of the plume using a new ground-water flow model of the Base. A benzene plume near the bulk-fuel storage area has shifted to a more northerly direction under influence of the Arrow Street purge system. Sites initially identified for purging the benzene plume have been repositioned because of the change in contaminant movement. JP-4 fuel was found to be accumulating in wells near the bulk-fuel storage area, largely in response to seasonal fluctuations in the water-table. It is thought to originate from a spill that occurred several years ago. In general, concentrations found in water do not differ greatly from those observed in 1981. Since 1981, concentrations of TCE have decreased significantly in the Alert Apron plume. Near the origin of the plume, the concentration of TCE has decreased from 1,000 microg/L in 1980 to 50 microg/L in 1984. Water from Van Etten Lake near the termination of the plume had only a trace of TCE at one site. Benzene detected in water from well AF2 seems to originate near the former site of buried fuel tanks west of the operational apron. During periods of normal purge pumping along Arrow Street, contaminants are drawn toward water-supply wells AF2, AF4, and AF5. (Author 's abstract)

Cummings, T.R.; Twenter, F.R.

1986-01-01

111

INDEPENDENT TECHNICAL REVIEW OF THE BUILDING 100 PLUME, FORMER DOE PINELLAS SITE (YOUNG - RAINEY STAR CENTER), LARGO, FLORIDA  

SciTech Connect

Contaminated groundwater associated with Building 100 at the Young-Rainey Science, Technology, and Research Center, formerly the DOE Pinellas plant, is the primary remedial challenge that remains to be addressed at the site. Currently, Building 100 is an active industrial facility that is now owned and operated by the Pinellas county government. Groundwater samples collected from monitoring wells recently installed near the southern boundary of the site suggest that contaminated groundwater has migrated off the plant site. In response to the challenges presented by the Building 100 plume, the Office of Legacy Management (LM) requested assistance from the DOE Office of Groundwater and Soil Remediation (EM-32) to provide a review team to make technical recommendations so that they can efficiently and effectively address characterization and remediation of the plume. The review team was unanimous in the conclusion that a dynamic strategy that combines a phased implementation of direct push samplers, sensors, and tools can be used to better delineate the extent of contamination, control plume migration, and rapidly remediate the contaminated groundwater at the site. The initial efforts of the team focused on reviewing the site history and data, organizing the information into a conceptual model, identifying appropriate technologies, and recommending an integrated strategy. The current groundwater data from the site indicate a two-lobed plume extending to the east and south. To the east vinyl chloride is the primary contaminant of concern, to the south, vinyl chloride and cis1, 2-DCE are the primary contaminants. The limited data that are available suggest that reductive dechlorination of the TCE is already occurring but is not sufficient to prevent offsite migration of low concentrations of TCE daughter products. The team recommends that DOE pursue a strategy that builds on the natural cleansing capacity of the subsurface with reductive methods including biostimulation and/or bioaugmentation to provide a sustainable remediation system within the flow path of the plume. Additional data will be required to implement this approach and will include: (1) Better delineation of the nature and extent of contamination; (2) Demonstration the plume is currently stable or shrinking; and (3) Demonstration the full reductive dechlorination is occurring. The technical team recommends that DOE use a phased approach to identify residual contamination and to provide rapid installation of remedies. Matrices of characterization and remediation sensors, technologies, and tools were developed by the team in order to match the specific conditions and requirements of the site. The team provides a specific example of remedy that includes the incorporation of a dynamic characterization strategy moving from minimally invasive to more aggressive field techniques, the consideration of multiple complementary remediation approaches based on a spatiotemporally phased approach keyed to the different demands of different parts of the plume, and the integration and sequencing of the characterization and remediation activities.

Eddy-Dilek, C.; Rossabi, J.; Amidon, M.; Riha, B.; Kaback, D.

2010-07-30

112

Mississippi Plumes  

NSDL National Science Digital Library

The MODIS satellite image above, taken on March 5, shows sediment plumes moving into the Gulf of Mexico from the main branch of the Mississippi River as well as through the bayous in its delta region. It's easy to understand how our nation's longest river is often referred to as 'The Big Muddy'. From the end of the last ice age until the mid 1900's, the Mississippi River created more area each year, but the river has been confined in it's levees since a major flood in 1927. The benefits of controlling the Mississippi River extend throughout the watershed because such control reduces the cost of exporting grain from the midwest and importing petroleum from around the world. Such benefits have come at a tremendous ecological cost that are concentrated in coastal Louisiana. Wetland loss there averaged an acre every 20 minutes throughout the 1950's, 1960's and 1970's. The most recent estimates are about an acre every 40 minutes. Before the mid 1900's, natural wetland loss processes were slower than natural wetland building processes, but human activities have accelerated wetland loss processes and virtually eliminated wetland creation processes.

Center, Nasa G.; Day, Earth S.

113

Review of Quantitative Surveys of the Length and Stability of MTBE, TBA, and Benzene Plumes in Groundwater at UST Sites.  

PubMed

Quantitative information regarding the length and stability condition of groundwater plumes of benzene, methyl tert-butyl ether (MTBE), and tert-butyl alcohol (TBA) has been compiled from thousands of underground storage tank (UST) sites in the United States where gasoline fuel releases have occurred. This paper presents a review and summary of 13 published scientific surveys, of which 10 address benzene and/or MTBE plumes only, and 3 address benzene, MTBE, and TBA plumes. These data show the observed lengths of benzene and MTBE plumes to be relatively consistent among various regions and hydrogeologic settings, with median lengths at a delineation limit of 10?µg/L falling into relatively narrow ranges from 101 to 185?feet for benzene and 110 to 178?feet for MTBE. The observed statistical distributions of MTBE and benzene plumes show the two plume types to be of comparable lengths, with 90th percentile MTBE plume lengths moderately exceeding benzene plume lengths by 16% at a 10-µg/L delineation limit (400?feet vs. 345?feet) and 25% at a 5-µg/L delineation limit (530?feet vs. 425?feet). Stability analyses for benzene and MTBE plumes found 94 and 93% of these plumes, respectively, to be in a nonexpanding condition, and over 91% of individual monitoring wells to exhibit nonincreasing concentration trends. Three published studies addressing TBA found TBA plumes to be of comparable length to MTBE and benzene plumes, with 86% of wells in one study showing nonincreasing concentration trends. PMID:25040137

Connor, John A; Kamath, Roopa; Walker, Kenneth L; McHugh, Thomas E

2014-07-12

114

Mann-Kendall Test for Analysis of Groundwater Contaminant Plume Stability and Evaluation of Sampling Frequency for Long-Term Monitoring - 13233  

SciTech Connect

This paper describes a spreadsheet-based approach for applying the Mann-Kendall (MK) Test to identify statistically significant increasing or decreasing concentration trends, stable concentration trends (not increasing or decreasing), and indeterminate concentration trends (no trend) defined by time-series groundwater monitoring data for inorganic, organic, or radiological contaminants. The approach has been applied in support of ongoing long-term monitoring (LTM) of groundwater contamination at the U.S. Department of Energy (DOE) Y-12 National Security Complex (Y-12) in Oak Ridge, Tennessee and elsewhere on the DOE Oak Ridge Reservation (ORR), and has proven effective at minimizing subjective bias in the evaluation and interpretation of contaminant concentration trend data. Application of the approach for the purposes of optimizing groundwater sampling frequency for LTM also is outlined. (authors)

Walker, Jeffrey R.; Harrison, Toby R. [Elvado Environmental LLC, 9724 Kingston Pike, Suite 603, Knoxville, TN 37922 (United States)] [Elvado Environmental LLC, 9724 Kingston Pike, Suite 603, Knoxville, TN 37922 (United States)

2013-07-01

115

Geophysical detection of on-site wastewater plumes in the North Carolina Coastal Plain, USA  

NASA Astrophysics Data System (ADS)

Nonpoint source pollution (NPS) continues to be the leading cause of water quality degradation in the United States. On-site wastewater systems (OWS) contribute to NPS; however, due to the range of system designs and complexity of the subsurface, OWS contributions to groundwater pollution are not well understood. As the population of coastal North Carolina continues to increase, better methods to locate and characterize wastewater impacted groundwater are needed. Previous studies have demonstrated the ability of non-intrusive geophysical methods to provide high resolution information on various contaminants in different geologic settings. The goals of this study were to evaluate the utility of ground penetrating radar (GPR) and capacitively coupled resistivity (CCR) for detecting OWS components, delineating associated wastewater plumes, and monitoring temporal variations in groundwater quality. Cross-sectional and three dimensional (3D) geophysical surveys were conducted periodically over a one year period (February 2011--January 2012) at two schools utilizing OWS in the lower Neuse River Basin (NRB) in the North Carolina Coastal Plain (NCCP). Cores were collected at both study sites; as well as monthly groundwater depth, temperature, and specific conductivity measurements to better constrain the geophysical interpretations. Additionally, dissolved inorganic nitrogen (DIN) and Cl concentrations were monitored bi-monthly to assess nutrient transport at the sites. The 3D GPR surveys effectively located the wastewater drainage trenches at both sites, in close agreement with locations described in as-built OWS blueprints. Regression analysis of resistivity versus groundwater specific conductivity revealed an inverse relationship, suggesting resistivity ? 250 ohm.m was indicative of wastewater impacted groundwater at both sites. The 3D resistivity models identified regions of low resistivity beneath the drainfields relative to background values. Regression analysis of GPR signal absolute peak amplitude (APA) versus groundwater specific conductivity revealed a decrease in APA indicative of radar signal attenuation at locations where groundwater specific conductivity was elevated. The 3D GPR models identified regions of attenuated radar signal beneath the drainfields relative to background locations. Comparisons of groundwater specific conductivity, GPR, and CCR lateral wastewater plume estimates indicated similar dimensions at both sites. The sensitivity of resistivity measurements tended to decline with increased water-table depth; although, differences in resistivity associated with seasonal water-table depth changes were noticeable. Overall, results of this study suggest that GPR and CCR surveys combined with sediment, hydrologic, and water quality data may provide reliable information on the location of OWS components and extent of associated wastewater plumes. The GPR surveys successfully located the wastewater drainage trenches and helped image the uppermost surface of the wastewater plumes. The CCR surveys delineated the lateral wastewater plume dimensions and revealed temporal changes in groundwater quality associated with differences in groundwater recharge.

Smith, Matthew

116

Plume development in Long Island Sound observed by remote sensing (ERTS-1)  

NASA Technical Reports Server (NTRS)

As the Connecticut River flows into Long Island Sound, large plumes are developed during the mixing of ocean and estuarine waters. Plumes were delineated for July 28, October 8, October 27, and December 2, 1972, by analyzing ERTS-1 imagery with the SRI electronic satellite image analysis console (ESIAC). Insertion of MSS band 5 into the ESIAC produced the best result in this analysis. The four plumes that have been delineated provide the first input to a time-lapse analysis of circulation patterns at the eastern end of Long Island Sound.

Ruggles, F. H., Jr.

1973-01-01

117

Scientific debate: Mantle plumes  

NSDL National Science Digital Library

After a preliminary discussion of hotspots (emphasizing the generic term melting anomalies), the mantle plume hypothesis, and alternative hypotheses, students are assigned roles for a debate on the mantle plume controversy. Students conduct an in-class debate, presenting arguments from opposite sides of the plume debate. After the debate students write a reflection paper on their perspective on the debate.

Jordan, Brennan

118

Geophysical discovery of a new LNAPL plume at the former Wurtsmith AFB, Oscoda, Michigan  

Microsoft Academic Search

A light nonaqueous phase liquid (LNAPL) ground water contaminant plume has been discovered by purely geophysical means at the former Wurtsmith Air Force Base (AFB) near Oscoda, Michigan. The plume was discovered by ground penetrating radar (GPR) profiling while extending a long line from FT-02 to establish background variability around that plume. Further GPR surveys were conducted by students of

Jose L. Bermejo; William A. Sauck; Estella A. Atekwana

1997-01-01

119

Containment of subsurface contaminants  

DOEpatents

A barrier for reducing the spread of a plume of subsurface contaminants. The apparatus includes a well system for injecting a fluid, such as air, just outside and below the periphery of the plume. The fluid is injected at a pressure sufficient to lower the hydraulic conductivity of the soil from the point of injection to the surface thus establishing a curtain-like barrier to groundwater movement. The barrier is established upgradient of the plume to divert groundwater away, or preferably completely around the plume to reduce the flow of groundwater into or out of the plume. The barrier enables the remediation of the confined contamination and then, when the injection of the fluid is halted, the barrier quickly dissipates.

Corey, John C. (Aiken, SC)

1994-01-01

120

Containment of subsurface contaminants  

DOEpatents

A barrier is disclosed for reducing the spread of a plume of subsurface contaminants. The apparatus includes a well system for injecting a fluid, such as air, just outside and below the periphery of the plume. The fluid is injected at a pressure sufficient to lower the hydraulic conductivity of the soil from the point of injection to the surface thus establishing a curtain-like barrier to groundwater movement. The barrier is established upgradient of the plume to divert groundwater away, or preferably completely around the plume to reduce the flow of groundwater into or out of the plume. The barrier enables the remediation of the confined contamination and then, when the injection of the fluid is halted, the barrier quickly dissipates. 5 figs.

Corey, J.C.

1994-09-06

121

Hydrogeological modeling constraints provided by geophysical and geochemical mapping of a chlorinated ethenes plume in northern France  

NASA Astrophysics Data System (ADS)

A methodological approach is described which combines geophysical and geochemical data to delineate the extent of a chlorinated ethenes plume in northern France; the methodology was used to calibrate a hydrogeological model of the contaminants' migration and degradation. The existence of strong reducing conditions in some parts of the aquifer is first determined by measuring in situ the redox potential and dissolved oxygen, dissolved ferrous iron and chloride concentrations. Electrical resistivity imaging and electromagnetic mapping, using the Slingram method, are then used to determine the shape of the pollutant plume. A decreasing empirical exponential relation between measured chloride concentrations in the water and aquifer electrical resistivity is observed; the resistivity formation factor calculated at a few points also shows a major contribution of chloride concentration in the resistivity of the saturated porous medium. MODFLOW software and MT3D99 first-order parent-daughter chain reaction and the RT3D aerobic-anaerobic model for tetrachloroethene (PCE)/trichloroethene (TCE) dechlorination are finally used for a first attempt at modeling the degradation of the chlorinated ethenes. After calibration, the distribution of the chlorinated ethenes and their degradation products simulated with the model approximately reflects the mean measured values in the observation wells, confirming the data-derived image of the plume.

Razafindratsima, Stephen; Guérin, Roger; Bendjoudi, Hocine; de Marsily, Ghislain

2014-09-01

122

Sewage plume in a sand and gravel aquifer, Cape Cod, Massachusetts  

USGS Publications Warehouse

Secondarily treated domestic sewage has been disposed of on surface sand beds at the sewage treatment facility at Otis Air Force Base, Massachusetts, since 1936. Infiltration of the sewage through the sand beds into the underlying unconfined sand and gravel aquifer has resulted in a plume of sewage-contaminated ground water that is 2,500 to 3,500 feet wide, 75 feet thick, and more than 11,000 feet long. The plume extends south and southwest of the sand beds in the same direction as the regional flow of ground water, and is overlain by 20 to 50 feet of ground water derived from precipitation that recharges the aquifer. The bottom of the plume generally coincides with the contact between the permeable sand and gravel and underlying finer grained sediments. The distributions in the aquifer of specific conductance, temperature, boron, chloride, sodium, phosphorus, nitrogen (total of all species), ammonia, nitrate, dissolved oxygen, and detergents are used to delineate the plume. In ground water outside the plume, the detergent concentration is less than 0.1 milligrams per liter as MBAS (methylene blue active substances), the ammonia-nitrogen concentration is less than 0.1 milligrams per liter, the boron concentration is less than 50 micrograms per liter, and specific conductance is less than 80 mircromhos per centimeter. In the center of the plume, detergent concentrations as high as 2.6 milligrams per liter as MBAS, ammonia-nitrogen concentrations as high as 20 milligrams per liter, boron concentrations as high as 400 micrograms per liter, and specific conductance as high as 405 micromhos per centimeter were measured. Chloride, sodium, and boron are transported by the southward-flowing ground water without significant retardation, and seem to be diluted only by hydrodynamic dispersion. The movement of phosphorus is greatly restricted by sorption. Phosphorus concentrations do not exceed 0.05 milligrams per liter farther than 2,500 feet from the sand beds. Detergent concentrations in the plume are highest between 3,000 and 10,000 feet from the sand beds and reflect the introduction of nonbiodegradable detergents in 1946 and the conversion to biodegradable detergents in 1964. The center of the plume as far as 5,000 feet from the sand beds contains nitrogen as ammonia, but no nitrate and no dissolved oxygen. Ammonia is gradually oxidized to nitrate between 5,000 and 8,000 feet from the sand beds, and at distances greater than 8,000 feet oxidation of ammonia is essentially complete. Ammonia also is oxidized to nitrate along the top and sides of the plume within 5,000 of the beds where the contaminated ground water mixes with uncontaminated ground water that contains up to 11 milligrams per liter dissolved oxygen.

LeBlanc, Denis R.

1984-01-01

123

Controls on plume heat flux and plume excess temperature  

Microsoft Academic Search

Plume heat flux and plume excess temperature in the upper mantle inferred from surface observations may pose important constraints on the heat flux from the core and mantle internal heating rate. This study examined the relationship between plume heat flux Q p , core-mantle boundary (CMB) heat flux Q cmb and plume excess temperature DeltaT plume in thermal convection using

Wei Leng; Shijie Zhong

2008-01-01

124

Distribution of microbial physiologic types in an aquifer contaminated by crude oil  

USGS Publications Warehouse

We conducted a plume-scale study of the microbial ecology in the anaerobic portion of an aquifer contaminated by crude-oil compounds. The data provide insight into the patterns of ecological succession, microbial nutrient demands, and the relative importance of free-living versus attached microbial populations. The most probable number (MPN) method was used to characterize the spatial distribution of six physiologic types: aerobes, denitrifiers, iron-reducers, heterotrophic fermenters, sulfate-reducers, and methanogens. Both free-living and attached numbers were determined over a broad cross-section of the aquifer extending horizontally from the source of the plume at a nonaqueous oil body to 66 m downgradient, and vertically from above the water table to the base of the plume below the water table. Point samples from widely spaced locations were combined with three closely spaced vertical profiles to create a map of physiologic zones for a cross-section of the plume. Although some estimates suggest that less than 1% of the subsurface microbial population can be grown in laboratory cultures, the MPN results presented here provide a comprehensive qualitative picture of the microbial ecology at the plume scale. Areas in the plume that are evolving from iron-reducing to methanogenic conditions are clearly delineated and generally occupy 25-50% of the plume thickness. Lower microbial numbers below the water table compared to the unsaturated zone suggest that nutrient limitations may be important in limiting growth in the saturated zone. Finally, the data indicate that an average of 15% of the total population is suspended.

Bekins, B.A.; Godsy, E.M.; Warren, E.

1999-01-01

125

Dynamics of Thermochemical Plumes  

NASA Astrophysics Data System (ADS)

We investigate the dynamics of thermo-chemical plumes to enlighten the fundamental differences with purely thermal plumes. The key features of our 3D numerical model include: (1) a compressible mantle with an endothermic phase transition at 670km depth, (2) a mantle 'wind' induced by the imposed surface plate motion, (3) twenty million active tracers simulate denser material initially in the lowermost mantle, (4) plumes form naturally i.e., without imposing any temperature perturbation. First, we investigate the widely accepted head-tail structure of plumes. Our results show that thermo-chemical plumes reaching the surface may or may not have a head since, in some cases, only a narrow 'tail' of hot material is able to ascend in the upper mantle. Therefore, we suggest that the existence of a large igneous province at the onset of hotspot volcanism is not a valid prerequisite for a deep plume origin. Second, we investigate the entrainment of deep heterogeneities. Our results show the generation of narrow, long lasting, distinct filaments in the plume's tail. Therefore, the plume conduit is laterally heterogeneous, rather than concentrically zoned. Third, we calculate the shear wave velocity anomalies in the lower mantle, using the temperature field and the distribution of chemical heterogeneities provided by the convection model. The great variety of plume's shapes and sizes differs strikingly from the expected 'mushroom' shape of purely thermal plumes, bearing important implications for the interpretation of seismologically detected plumes. Finally, our model predictions will be compared with a variety of observations in the Central Pacific.

Farnetani, C. G.; Samuel, H.

2004-12-01

126

Evidence for Little Shallow Entrainment in Starting Mantle Plumes  

NASA Astrophysics Data System (ADS)

Basalts from intraplate or hotspot ocean islands show distinct geochemical signatures. Their diversity in composition is generally believed to result from the upwelling plume entraining shallow mantle material during ascent, while potentially also entraining other deep regions of the mantle. Here we present results from analogue laboratory experiments and numerical modelling that there is evidence for little shallow entrainment into ascending mantle plumes, i.e. most of the plume signature is inherited from the source. We conducted laboratory experiments using glucose syrup contaminated with glass beads to visualize fluid flow and origin. The plume is initiated by heating from below or by injecting hot, uncontaminated syrup. Particle movement is captured by a CCD camera. In our numerical experiments we solve the Stokes equations for a viscous fluid at infinite Prandtl number with passive tracer particles being used to track fluid flow and entrainment rates, simulating laboratory as well as mantle conditions. In both analogue experiments and numerical models we observe the classical plume structure being embedded in a `sheath' of material from the plume source region that retains little of the original temperature anomaly of the plume source. Yet, this sheath ascends in the `slipstream' of the plume at speeds close to the ascent speed of the plume head, and effectively prevents the entrainment of surrounding material into the plume head or plume tail. We find that the source region is most effectively sampled by an ascending plume and that compositional variations in the source region are preserved during plume ascent. The plume center and plume sheath combined are composed of up to 85% source material. However, there is also evidence of significant entrainment of up to 30% of surrounding material into the outer layers of the plume sheath. Entrainment rates are found to be influenced by mantle composition and structure, with the radial viscosity profile of the mantle being an important factor in determining plume flow and entrainment rates. Prominent mantle discontinuities (e.g. 410km, 660 km) can slow down or speed up plume ascent significantly, thus affecting which regions of the mantle are sampled efficiently.

Lohmann, F. C.; Phipps Morgan, J.; Hort, M.

2005-12-01

127

Density-current plumes.  

PubMed

Diurnal solar heating produces an unstable warm zone just off the bottom of the inshore regions of a salt lake. The warm water rises in plumes in which brine shrimp become entrapped through apparently negative photokinetic behavior. The plumes of concentrated shrimp resemble those composed of insects in air. PMID:17775163

Mason, D T

1966-04-15

128

Density-Current Plumes  

Microsoft Academic Search

Diurnal solar heating produces an unstable warm zone just off the bottom of the inshore regions of a salt lake. The warm water rises in plumes in which brine shrimp become entrapped through apparently negative photokinetic behavior. The plumes of concentrated shrimp resemble those composed of insects in air.

David T. Mason

1966-01-01

129

COOLING TOWER PLUME MODEL  

EPA Science Inventory

A review of recently reported cooling tower plume models yields none that is universally accepted. The entrainment and drag mechanisms and the effect of moisture on the plume trajectory are phenomena which are treated differently by various investigators. In order to better under...

130

Estuarine and coastal water dynamics controlling sediment movement and plume development in Long Island Sound  

NASA Technical Reports Server (NTRS)

The author has identified the following significant results. As the Connecticut River flows into Long Island Sound, large plumes develop during the mixing of ocean and estuarine waters. Plumes were delineated for July 28, October 8, October 27, and December 2, 1972, by analyzing ERTS-1 imagery with the SRI Electronic Satellite Image Analysis Console (ESIAC). Because the chemical and physical composition of the plume and ocean water were not too different, the ESIAC was utilized to expand the scenes and subject the transparencies to varying combinations of viewing techniques to identify and delineate the plumes. Best results were obtained when band 5 transparencies were used. Indications are, when the scene being analyzed is predominantly in the first two steps of the gray scale, it is best to use the negative transparencies. When the analysis is being done above the first two steps of the gray scale, it is best to use the positive transparencies.

Ruggles, F. H., Jr. (principal investigator)

1973-01-01

131

Colloid Formation at Waste Plume Fronts  

SciTech Connect

Highly saline and caustic tank waste solutions containing radionuclides and toxic metals have leaked into sediments at U. S. Department of Energy (DOE) facilities such as the Hanford Site (Washington State). Colloid transport is frequently invoked to explain migration of radionuclides and metals in the subsurface. To understand colloid formation during interactions between highly reactive fluids and sediments and its impact on contaminant transport, we simulated tank waste solution (TWS) leakage processes in laboratory columns at ambient and elevated (70 C) temperatures. We found that maximum formation of mobile colloids occurred at the plume fronts (hundreds to thousands times higher than within the plume bodies or during later leaching). Concentrations of suspended solids were as high as 3 mass%, and their particle-sizes ranged from tens of nm to a few {micro}m. Colloid chemical composition and mineralogy depended on temperature. During infiltration of the leaked high Na{sup +} waste solution, rapid and completed Na{sup +} replacement of exchangeable Ca{sup 2+} and Mg{sup 2+} from the sediment caused accumulation of these divalent cations at the moving plume front. Precipitation of supersaturated Ca{sup 2+}/Mg{sup 2+}-bearing minerals caused dramatic pH reduction at the plume front. In turn, the reduced pH caused precipitation of other minerals. This understanding can help predict the behavior of contaminant trace elements carried by the tank waste solutions, and could not have been obtained through conventional batch studies.

Wan, Jiamin; Tokunaga, Tetsu K.; Saiz, Eduardo; Larsen, Joern T.; Zheng, Zuoping; Couture, Rex A.

2004-05-22

132

Controls on plume heat flux and plume excess temperature  

Microsoft Academic Search

Plume heat flux and plume excess temperature in the upper mantle inferred from surface observations may pose important constraints on the heat flux from the core and mantle internal heating rate. This study examined the relationship between plume heat flux Qp, core-mantle boundary (CMB) heat flux Qcmb and plume excess temperature ?Tplume in thermal convection using both numerical modeling and

Wei Leng; Shijie Zhong

2008-01-01

133

Seismological images of plumes  

NASA Astrophysics Data System (ADS)

The existence, physical character and morphology of mantle plumes have been widely debated for over forty years. Geodynamical and seismological investigations, the two main approaches for inferring deep Earth structure, lead to very different interpretations of Earth dynamics. The existence of at least one thermal boundary layer within the mantle (i.e., core-mantle boundary) and estimates of convective vigor from surface heat flow observations still provides a theoretical argument for the well-known “head” and “tail” plume. However associated thin cylindrical structures reaching from the Earth’s surface to the core are not clearly distinguished in blurry tomographic images. An inability to image fine-scale plume structures in the lower mantle is due to the inherently poor (compared to geodynamical models) and highly heterogeneous spatial resolution of tomographic models, and perhaps also to erroneous characterization of Earth-physics in geodynamical models. We generate synthetic tomographic images of mantle plumes using a three stage technique. First we develop 2D axisymmetric spherical models of plausible plume structures extending the models of [Lin and van Keken, 2006] for example by including the effects of compressibility and depth dependent viscosity. We maximize computational efficiency by employing a series of locally refined meshes tailored to the position of the plume “head” and “tail”. Initial investigations show that the plume velocity is sensitive to the thickness of the initial thermal boundary layer and the harmonic initial condition. The plume morphology is additionally altered when compressibility and depth-dependent viscosity is implemented. Secondly, we map thermal structure from the geodynamic models to seismic velocities using constraints from mineral physics data [Xu et al., 2008], and finally we apply the tomographic filter of the S20RTS global shear wave tomographic model [Ritsema et al., 2007] to the images of seismic wave speed to determine the tomographic expression of our plumes.

Smith, H. E.; Styles, E. E.; van Keken, P. E.; Goes, S. D.; Ritsema, J. E.

2009-12-01

134

In-situ remediation system and method for contaminated groundwater  

DOEpatents

A system for removing volatile contaminants from a subsurface plume of contamination comprising two sets of wells, a well for injecting a fluid into a saturated zone on one side of the plume and an extracting well for collecting the fluid together with volatilized contaminants from the plume on the other side of the plume. The fluid enables the volatile contaminants to be volatilized and carried therewith through the ground to the extracting well. Injecting and extracting wells are preferably horizontal wells positioned below the plume in the saturated zone and above the plume in the vadose zone, respectively. The fluid may be air or other gas or a gas and liquid mixture depending on the type of contaminant to be removed and may be preheated to facilitate volatilization. Treatment of the volatilized contamination may be by filtration, incineration, atmospheric dispersion or the like.

Corey, John C. (Aiken, SC); Looney, Brian B. (Aiken, SC); Kaback, Dawn S. (Aiken, SC)

1989-01-01

135

In-situ remediation system and method for contaminated groundwater  

DOEpatents

A system for removing volatile contaminants from a subsurface plume of contamination comprising two sets of wells, a well for injecting a fluid into a saturated zone on one side of the plume and an extracting well for collecting the fluid together with volatilized contaminants from the plume on the other side of the plume. The fluid enables the volatile contaminants to be volatilized and carried therewith through the ground to the extracting well. Injecting and extracting wells are preferably horizontal wells positioned below the plume in the saturated zone and above the plume in the vadose zone, respectively. The fluid may be air or other gas or a gas and liquid mixture depending on the type of contaminant to be removed and may be preheated to facilitate volatilization. Treatment of the volatilized contamination may be by filtration, incineration, atmospheric dispersion or the like. 3 figs.

Corey, J.C.; Looney, B.B.; Kaback, D.S.

1989-05-23

136

Nested monitoring approaches to delineate groundwater trichloroethene discharge to a UK lowland stream at multiple spatial scales.  

PubMed

Integrated approaches for the identification of pollutant linkages between aquifers and streams are of crucial importance for evaluating the environmental risks posed by industrial contaminants like trichloroethene (TCE). This study presents a systematic, multi-scale approach to characterising groundwater TCE discharge to a 'gaining' UK lowland stream receiving baseflow from a major Permo-Triassic sandstone aquifer. Beginning with a limited number of initial monitoring points, we aim to provide a 'first pass' mechanistic understanding of the plume's fate at the aquifer/stream interface using a novel combination of streambed diffusion samplers, riparian monitoring wells and drive-point mini-piezometers in a spatially nested sampling configuration. Our results indicate the potential discharge zone of the plume to extend along a stream reach of 120 m in length, delineated by a network of 60 in-situ diffusion samplers. Within this section, a 40 m long sub-reach of higher concentration (>10 ?g L(-1)) was identified; centred on a meander bend in the floodplain. 25 multi-level mini-piezometers installed to target this down-scaled reach revealed even higher TCE concentrations (20-40 ?g L(-1)), significantly above alluvial groundwater samples (<6 ?g L(-1)) from 15 riparian monitoring wells. Significant lateral and vertical spatial heterogeneity in TCE concentrations within the top 1m of the streambed was observed with the decimetre-scale vertical resolution provided by multi-level mini-piezometers. It appears that the distribution of fine-grained material in the Holocene deposits of the riparian floodplain and below the channel is exerting significant local-scale geological controls on the location and magnitude of the TCE discharge. Large-scale in-situ biodegradation of the plume was not evident during the monitoring campaigns. However, detections of cis-1,2-dichloroethene and vinyl chloride in discrete sections of the sediment profile indicate that shallow (e.g., <20 cm) TCE transformation may be significant at a local scale in the streambed deposits. Our findings highlight the need for efficient multi-scale monitoring strategies in geologically heterogeneous lowland stream/aquifer systems in order to more adequately quantify the risk to surface water ecological receptors posed by point-source groundwater contaminants like TCE. PMID:24424265

Weatherill, John; Krause, Stefan; Voyce, Kevin; Drijfhout, Falko; Levy, Amir; Cassidy, Nigel

2014-03-01

137

WETLAND DELINEATION REPORT UMORE MINING AREA  

E-print Network

Project 08-0092 September 29, 2009 #12;UMore Gravel EIS ­ Empire Township Wetland Delineation #12;UMore Gravel EIS ­ Empire Township Wetland Delineation TABLE OF CONTENTS 1.0. INTRODUCTION Determination Form #12;UMore Gravel EIS ­ Empire Township Wetland Delineation #12;UMore Gravel EIS ­ Empire

Netoff, Theoden

138

CHLORINATED SOLVENT PLUME CONTROL  

EPA Science Inventory

This lecture will cover recent success in controlling and assessing the treatment of shallow ground water plumes of chlorinated solvents, other halogenated organic compounds, and methyl tert-butyl ether (MTBE)....

139

Sulfur plumes off Namibia  

NASA Technical Reports Server (NTRS)

Sulfur plumes rising up from the bottom of the ocean floor produce colorful swirls in the waters off the coast of Namibia in southern Africa. The plumes come from the breakdown of marine plant matter by anaerobic bacteria that do not need oxygen to live. This image was acquired by the Moderate Resolution Imaging Spectroradiometer (MODIS) on the Terra satellite on April 24, 2002 Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

2002-01-01

140

Stochastic analytical modeling of the biodegradation of steady plumes  

NASA Astrophysics Data System (ADS)

We present a stochastic analytical framework to assess the contaminant concentration of a steady plume undergoing biodegradation. The method is focused on heterogeneous formations, and it embeds both fringe and core degradation. The Lagrangian concentration approach of Fiori (2001) was employed, which is suited for describing the interplay between the large scale advection caused by heterogeneity and the local dispersion processes. The principal scope of the model is to provide a relatively simple tool for a quick assessment of the contamination level in aquifers, as function of a few relevant, physically based dimensionless parameters. The solution of the analytical model is relatively simple and generalizes previous approaches developed for homogeneous formations. It is found that heterogeneity generally enhances mixing and degradation; in fact, the plume shear and distortion operated by the complex, heterogeneous velocity field facilitates local dispersion in diluting the contaminant and mixing it with the electron acceptor. The decay of the electron donor concentration, and so the plume length, is proportional to the transverse pore-scale dispersivity, which is indeed the parameter ruling mixing and hence degradation. While the theoretical plume length is controlled by the fringe processes, the core degradation may determine a significant decay of concentration along the mean flow direction, thus affecting the length of the plume. The method is applied to the crude oil contamination event at the Bemijdi site, Minnesota (USA).

Zarlenga, A.; Fiori, A.

2014-02-01

141

Biogeochemical evolution of a landfill leachate plume, Norman, Oklahoma  

USGS Publications Warehouse

Leachate from municipal landfills can create groundwater contaminant plumes that may last for decades to centuries. The fate of reactive contaminants in leachate-affected aquifers depends on the sustainability of biogeochemical processes affecting contaminant transport. Temporal variations in the configuration of redox zones downgradient from the Norman Landfill were studied for more than a decade. The leachate plume contained elevated concentrations of nonvolatile dissolved organic carbon (NVDOC) (up to 300 mg/L), methane (16 mg/L), ammonium (650 mg/L as N), iron (23 mg/L), chloride (1030 mg/L), and bicarbonate (4270 mg/L). Chemical and isotopic investigations along a 2D plume transect revealed consumption of solid and aqueous electron acceptors in the aquifer, depleting the natural attenuation capacity. Despite the relative recalcitrance of NVDOC to biodegradation, the center of the plume was depleted in sulfate, which reduces the long-term oxidation capacity of the leachate-affected aquifer. Ammonium and methane were attenuated in the aquifer relative to chloride by different processes: ammonium transport was retarded mainly by physical interaction with aquifer solids, whereas the methane plume was truncated largely by oxidation. Studies near plume boundaries revealed temporal variability in constituent concentrations related in part to hydrologic changes at various time scales. The upper boundary of the plume was a particularly active location where redox reactions responded to recharge events and seasonal water-table fluctuations. Accurately describing the biogeochemical processes that affect the transport of contaminants in this landfill-leachate-affected aquifer required understanding the aquifer's geologic and hydrodynamic framework.

Cozzarelli, Isabelle M.; Bohlke, Johnkarl F.; Masoner, Jason R.; Breit, George N.; Lorah, Michelle M.; Tuttle, Michele L.; Jaeschke, Jeanne B.

2011-01-01

142

Stormwater plume detection by MODIS imagery in the southern California coastal ocean  

NASA Astrophysics Data System (ADS)

Stormwater plumes in the southern California coastal ocean were detected by MODIS-Aqua satellite imagery and compared to ship-based data on surface salinity and fecal indicator bacterial (FIB) counts collected during the Bight'03 Regional Water Quality Program surveys in February-March of 2004 and 2005. MODIS imagery was processed using a combined near-infrared/shortwave-infrared (NIR-SWIR) atmospheric correction method, which substantially improved normalized water-leaving radiation (nLw) optical spectra in coastal waters with high turbidity. Plumes were detected using a minimum-distance supervised classification method based on nLw spectra averaged within the training areas, defined as circular zones of 1.5-5.0-km radii around field stations with a surface salinity of S < 32.0 ("plume") and S > 33.0 ("ocean"). The plume optical signatures (i.e., the nLw differences between "plume" and "ocean") were most evident during the first 2 days after the rainstorms. To assess the accuracy of plume detection, stations were classified into "plume" and "ocean" using two criteria: (1) "plume" included the stations with salinity below a certain threshold estimated from the maximum accuracy of plume detection; and (2) FIB counts in "plume" exceeded the California State Water Board standards. The salinity threshold between "plume" and "ocean" was estimated as 32.2. The total accuracy of plume detection in terms of surface salinity was not high (68% on average), seemingly because of imperfect correlation between plume salinity and ocean color. The accuracy of plume detection in terms of FIB exceedances was even lower (64% on average), resulting from low correlation between ocean color and bacterial contamination. Nevertheless, satellite imagery was shown to be a useful tool for the estimation of the extent of potentially polluted plumes, which was hardly achievable by direct sampling methods (in particular, because the grids of ship-based stations covered only small parts of the plumes detected via synoptic MODIS imagery). In most southern California coastal areas, the zones of bacterial contamination were much smaller than the areas of turbid plumes; an exception was the plume of the Tijuana River, where the zone of bacterial contamination was comparable with the zone of plume detected by ocean color.

Nezlin, Nikolay P.; DiGiacomo, Paul M.; Diehl, Dario W.; Jones, Burton H.; Johnson, Scott C.; Mengel, Michael J.; Reifel, Kristen M.; Warrick, Jonathan A.; Wang, Menghua

2008-10-01

143

Collapse in Thermal Plumes  

NASA Astrophysics Data System (ADS)

Collapsing thermal plumes have been investigated through experimental and numerical simulations. Collapsing plumes are an uncommon fluid dynamical phenomenon, usually seen when the buoyancy source is turned off. A series of fluid dynamical experiments were conducted on thermal plumes at a variety of temperature and viscosity contrasts, in a 26.5 cm^3 cubic tank heated by a constant temperature heater 2 cm in diameter and no-slip bottom and top surfaces. Working fluids included Lyle's Golden Syrup and ADM's Liquidose 436 syrup, which have strongly-temperature dependent viscosity and high Pr number (10^3-10^7 at experimental conditions). Visualisation included white light shadowgraphs and PIV of the central plane. Temperature contrasts ranged from 3-60°C, and two differing forms of collapse were identified. At very low temperature differences 'no rise' collapse was discovered, where the plumes stagnate in the lower third of the tank before collapsing. At temperature differences between 10-23°C normal evolution occurred until 'lens shape' collapse developed between midway and two-thirds of the distance from the base. The lens shape originated in the top of the conduit and was present throughout collapse. At temperatures above ?T=23°C the plumes follow the expected growth and shape and flatten out at the top of the tank. Thermal collapse remains difficult to explain given experimental conditions (continuous heating). Instead it is possible that small density differences arising from crystallization at ambient temperatures changes plume buoyancy-inducing collapse. We show results on the evolution of the refractive index of the syrup through time to ascertain this possibility. Preliminary numerical results using Fluidity will be presented to explore a greater parameter range of viscosity contrasts and tank aspect ratios.

Pears, M. I.; Lithgow-Bertelloni, C. R.; Dobson, D. P.; Davies, R.

2013-12-01

144

An assessment of natural biotransformation of petroleum hydrocarbons and chlorinated solvents at an aquifer plume transect  

Microsoft Academic Search

Field biogeochemical characterization and laboratory microcosm studies were performed to assess the potential for future biotransformation of trichloroethylene (TCE) and toluene in a plume containing petroleum hydrocarbons and chlorinated solvents at the former Wurtsmith Air Force Base in Oscoda, MI. In situ terminal electron accepting processes (TEAPs), contaminant composition and microbial phylogeny were studied at a plume transect 100 m

Karen L. Skubal; Michael J. Barcelona; Peter Adriaens

2001-01-01

145

Beyond the thermal plume paradigm  

NASA Astrophysics Data System (ADS)

Geodynamic models of thermo-chemical plumes rising in a mantle wind suggest that we should abandon some paradigms based on the dynamics of purely thermal axisymmetric plumes. The head-tail structure is possible but not unique and the lack of a plume head does not preclude a deep origin. Our results suggest that the surface expression of some thermo-chemical plumes may be a headless, age-progressive volcanic chain. Plume tails are laterally heterogeneous, rather than concentrically zoned, because deep heterogeneities are sheared into distinct and long-lasting filaments that will be successively sampled by different volcanoes, as the oceanic plate moves over the plume tail. Finally, calculated S-wave velocity anomalies are consistent with recent plume tomographic images, showing that compositional heterogeneities in the lowermost mantle favour the coexistence of a great variety of plume shapes and sizes.

Farnetani, C. G.; Samuel, H.

2005-04-01

146

Volcanic Plume Measurements with UAV (Invited)  

NASA Astrophysics Data System (ADS)

Volatiles in magmas are the driving force of volcanic eruptions and quantification of volcanic gas flux and composition is important for the volcano monitoring. Recently we developed a portable gas sensor system (Multi-GAS) to quantify the volcanic gas composition by measuring volcanic plumes and obtained volcanic gas compositions of actively degassing volcanoes. As the Multi-GAS measures variation of volcanic gas component concentrations in the pumped air (volcanic plume), we need to bring the apparatus into the volcanic plume. Commonly the observer brings the apparatus to the summit crater by himself but such measurements are not possible under conditions of high risk of volcanic eruption or difficulty to approach the summit due to topography etc. In order to overcome these difficulties, volcanic plume measurements were performed by using manned and unmanned aerial vehicles. The volcanic plume measurements by manned aerial vehicles, however, are also not possible under high risk of eruption. The strict regulation against the modification of the aircraft, such as installing sampling pipes, also causes difficulty due to the high cost. Application of the UAVs for the volcanic plume measurements has a big advantage to avoid these problems. The Multi-GAS consists of IR-CO2 and H2O gas analyzer, SO2-H2O chemical sensors and H2 semiconductor sensor and the total weight ranges 3-6 kg including batteries. The necessary conditions of the UAV for the volcanic plumes measurements with the Multi-GAS are the payloads larger than 3 kg, maximum altitude larger than the plume height and installation of the sampling pipe without contamination of the exhaust gases, as the exhaust gases contain high concentrations of H2, SO2 and CO2. Up to now, three different types of UAVs were applied for the measurements; Kite-plane (Sky Remote) at Miyakejima operated by JMA, Unmanned airplane (Air Photo Service) at Shinomoedake, Kirishima volcano, and Unmanned helicopter (Yamaha) at Sakurajima volcano operated by ERI, Tokyo University. In all cases, we could estimated volcanic gas compositions, such as CO2/SO2 ratios, but also found out that it is necessary to improve the techniques to avoid the contamination of the exhaust gases and to approach more concentrated part of the plume. It was also revealed that the aerial measurements have an advantage of the stable background. The error of the volcanic gas composition estimates are largely due to the large fluctuation of the atmospheric H2O and CO2 concentrations near the ground. The stable atmospheric background obtained by the UAV measurements enables accurate estimate of the volcanic gas compositions. One of the most successful measurements was that on May 18, 2011 at Shinomoedake, Kirishima volcano during repeating Vulcanian eruption stage. The major component composition was obtained as H2O=97, CO2=1.5, SO2=0.2, H2S=0.24, H2=0.006 mol%; the high CO2 contents suggests relatively deep source of the magma degassing and the apparent equilibrium temperature obtained as 400°C indicates that the gas was cooled during ascent to the surface. The volcanic plume measurement with UAV will become an important tool for the volcano monitoring that provides important information to understand eruption processes.

Shinohara, H.; Kaneko, T.; Ohminato, T.

2013-12-01

147

Enceladus' Water Vapour Plumes  

NASA Technical Reports Server (NTRS)

A viewgraph presentation on the discovery of Enceladus water vapor plumes is shown. Conservative modeling of this water vapor is also presented and also shows that Enceladus is the source of most of the water required to supply the neutrals in Saturn's system and resupply the E-ring against losses.

Hansen, Candice J.; Esposito, L.; Colwell, J.; Hendrix, A.; Matson, Dennis; Parkinson, C.; Pryor, W.; Shemansky, D.; Stewart, I.; Tew, J.; Yung, Y.

2006-01-01

148

Double Diffusive Plumes  

Microsoft Academic Search

Sour gas flares attempt to dispose of deadly H2S gas through combustion. What does not burn rises as a buoyant plume. But the gas is heavier than air at room temperature, so as the rising gas cools eventually it becomes negatively buoyant and descends back to the ground. Ultimately, our intent is to predict the concentrations of the gas at

Bruce Sutherland; Brace Lee

2008-01-01

149

Buoyant plume calculations  

SciTech Connect

Smoke from raging fires produced in the aftermath of a major nuclear exchange has been predicted to cause large decreases in surface temperatures. However, the extent of the decrease and even the sign of the temperature change, depend on how the smoke is distributed with altitude. We present a model capable of evaluating the initial distribution of lofted smoke above a massive fire. Calculations are shown for a two-dimensional slab version of the model and a full three-dimensional version. The model has been evaluated by simulating smoke heights for the Hamburg firestorm of 1943 and a smaller scale oil fire which occurred in Long Beach in 1958. Our plume heights for these fires are compared to those predicted by the classical Morton-Taylor-Turner theory for weakly buoyant plumes. We consider the effect of the added buoyancy caused by condensation of water-laden ground level air being carried to high altitude with the convection column as well as the effects of background wind on the calculated smoke plume heights for several fire intensities. We find that the rise height of the plume depends on the assumed background atmospheric conditions as well as the fire intensity. Little smoke is injected into the stratosphere unless the fire is unusually intense, or atmospheric conditions are more unstable than we have assumed. For intense fires significant amounts of water vapor are condensed raising the possibility of early scavenging of smoke particles by precipitation. 26 references, 11 figures.

Penner, J.E.; Haselman, L.C.; Edwards, L.L.

1985-01-01

150

PLUME and research sotware  

NASA Astrophysics Data System (ADS)

The PLUME open platform (https://www.projet-plume.org) has as first goal to share competences and to value the knowledge of software experts within the French higher education and research communities. The project proposes in its platform the access to more than 380 index cards describing useful and economic software for this community, with open access to everybody. The second goal of PLUME focuses on to improve the visibility of software produced by research laboratories within the higher education and research communities. The "development-ESR" index cards briefly describe the main features of the software, including references to research publications associated to it. The platform counts more than 300 cards describing research software, where 89 cards have an English version. In this talk we describe the theme classification and the taxonomy of the index cards and the evolution with new themes added to the project. We will also focus on the organisation of PLUME as an open project and its interests in the promotion of free/open source software from and for research, contributing to the creation of a community of shared knowledge.

Baudin, Veronique; Gomez-Diaz, Teresa

2013-04-01

151

COLD WEATHER PLUME STUDY  

EPA Science Inventory

While many studies of power plant plume transport and transformation have been performed during the summer, few studies of these processes during the winter have been carried out. Accordingly, the U.S. Environmental Protection Agency and the Electric Power Research Institute join...

152

Use of 2D and 3D Resistivity Methods to Monitor Dilution of a Conductive Plume in Fractured Basalt  

NASA Astrophysics Data System (ADS)

2D cross-borehole and 3D surface electrical resistance tomography (ERT) methods have been shown to be useful in delineating conductive plume migration in porous media. However, their application in fractured basalt, and to monitoring in situ dilution of conductive plumes has been largely uninvestigated. The objective of this study was to monitor the dilution of a conductive plume by more resistive water to delineate the spatial distribution of resistivity changes over time. Eight wells were drilled for the hydrogeophysical experiments. A KCl solution was injected into the partially saturated, fractured basalt via a centrally located injection well for 76 days prior to this dilution experiment. Tap water was then injected into the injection well for 34 days. ERT was used to monitor the dilution and displacement of the KCl plume during tap water injection, and during a subsequent 62-day monitoring period. Data were collected between the wells and at land surface. The ERT data collected during the investigation show the spatial distribution of resistivity changes caused by the influx of diluting water. 3D images of surface ERT results delineate broad areas of increased resistivity due to dilution/displacement of the KCl plume. Cross-borehole ERT data delineate specific locations of water influx. Injection-well resistivities delineate specific locations where tap water seeped from the injection well via preferential flow paths determined by time-dependent resistivity increases at different elevations. Monitoring- well resistivities delineate specific fracture locations and clustered areas of resistivity changes due to the dilution and displacement of the KCl solution. The experimental results presented herein illustrate the application of combined ERT methods to delineate spatially distributed dilution in fractured rock.

Nimmer, R. E.; Osiensky, J. L.; Binley, A. M.; Sprenke, K. F.; Williams, B. C.

2006-12-01

153

Geoelectrical Effects Associated With the Presence of Bacteria in Contaminated Groundwater  

NASA Astrophysics Data System (ADS)

Strong electrical potential anomalies (up to several hundreds of mV) have been evidenced at the ground surface above contaminant plumes rich in organic matter. These electrical disturbances, recordable with non-polarizable electrodes as "self-potential signals", allow to delineate the shape of these plumes and their dynamics. We have investigated the physics behind this geobattery process. Our conclusions are that biofilms, mainly located at the boundaries of the plume where both nutrients and oxygen are available (Monod kinetics), allow the transfer of electrons between the reduced and the oxidized parts of the system. The resulting current density produces electromagnetic disturbances in the Maxwell equations. We show from models, field and sandbox experiments that the electrical potential can be used to determine the redox potential at depth with a minimum of calibration with in situ measurements. Therefore, this method can be used as a redox non-intrusive sensor. The model implies that the areas rich in bacteria are also associated with anomalous high electrical conductivity and induced polarization anomalies as suggested from experiments by E. Atekwana, L. Slater, and co-workers.

Revil, A.; Naudet, V.

2004-12-01

154

Electrical resistivity imaging of conductive plume dilution in fractured rock  

NASA Astrophysics Data System (ADS)

Electrical resistance tomography (ERT) was used to monitor a conductive plume dilution experiment that was conducted in fractured basalt in order to assess its applications in this type of fractured-rock environment. Tap water was injected into an injection well for 34 days to dilute a pre-existing potassium chloride (KCl) plume at a site in Idaho, USA. No further fluids were introduced artificially during a 62-day monitoring period. Both surface ERT and cross-borehole ERT were used to monitor dilution and displacement of the plume. A square grid of land-surface electrodes was used with the surface ERT. Three-dimensional images of surface ERT delineated areas of increased and decreased resistivities. Increasing resistivities are attributed to dilution/displacement of the KCl solution by tap-water invasion or the influx of seasonal recharge. Decreasing resistivities resulted from redistribution of residual KCl solution. Cross-borehole ERT was conducted between the injection well and each of seven surrounding monitoring wells. Polar plots of the injection-well resistivity data in the direction of each monitoring well delineate specific locations where tap water seeped from the injection well via preferential flow paths determined by time-dependent resistivity increases. Monitoring-well data indicate locations of clustered and isolated regions of resistivity changes.

Nimmer, Robin E.; Osiensky, James L.; Binley, Andrew M.; Sprenke, Kenneth F.; Williams, Barbara C.

2007-08-01

155

Hydraulic gradient control for groundwater contaminant removal  

USGS Publications Warehouse

The Rocky Mountain Arsenal near Denver, Colarado, U.S.A., is used as a realistic setting for a hypothetical test of a procedure that plans the hydraulic stabilization and removal of a groundwater contaminant plume. A two-stage planning procedure successfully selects the best wells and their optimal pumping/recharge schedules to contain the plume while a well or system of wells within the plume removes the contaminated water. In stage I, a combined groundwater flow and solute transport model is used to simulate contaminant removal under an assumed velocity field. The result is the approximated plume boundary location as a function of time. In stage II, a linear program, which includes a groundwater flow model as part of the set of constraints, determines the optimal well selection and their optimal pumping/recharge schedules by minimizing total pumping and recharge. The simulation-management model eliminates wells far from the plume perimeter and activates wells near the perimeter as the plume decreases in size. This successfully stablizes the hydraulic gradient during aquifer cleanup.The Rocky Mountain Arsenal near Denver, Colorado, USA, is used as a realistic setting for a hypothetical test of a procedure that plans the hydraulic stabilization and removal of a groundwater contaminant plume. A two-stage planning procedure successfully selects the best wells and their optimal pumping/recharge schedules to contain the plume while a well or system of wells within the plume removes the contaminated water. In stage I, a combined groundwater flow and solute transport model is used to simulate contaminant removal under an assumed velocity field. The result is the approximated plume boundary location as a function of time. In stage II, a linear program, which includes a groundwater flow model as part of the set of constraints, determines the optimal well selection and their optimal pumping/recharge schedules by minimizing total pumping and recharge. Refs.

Fisher, Atwood D.; Gorelick, S.M.

1985-01-01

156

Enhanced biodegradation by hydraulic heterogeneities in petroleum hydrocarbon plumes  

Microsoft Academic Search

In case of dissolved electron donors and acceptors, natural attenuation of organic contaminant plumes in aquifers is governed by hydrodynamic mixing and microbial activity. Main objectives of this work were (i) to determine whether aerobic and anaerobic biodegradation in porous sediments is controlled by transverse dispersion, (ii) to elucidate the effect of sediment heterogeneity on mixing and biodegradation, and (iii)

Robert D. Bauer; Massimo Rolle; Sebastian Bauer; Christina Eberhardt; Peter Grathwohl; Olaf Kolditz; Rainer U. Meckenstock; Christian Griebler

2009-01-01

157

Sampling by mantle plumes : the legacy of the plume source  

NASA Astrophysics Data System (ADS)

Plumes in the Earth's mantle are considered to be at the origin of intraplate volcanism (or hotspots). They continue to fascinate the scientific community by the heterogeneity of the material they sample on the surface of our planet. To characterize what part of the mantle is sampled by plumes, we have developed a laboratory model for laminar thermal plumes at high Prandtl number, in a fluid whose viscosity depends strongly on the temperature. This study describes the precise phenomenology of the plume and proposes scaling laws for the speed and temperature of the conduit of the plume. We show a strong dependence of these features of the plume with the Rayleigh number and viscosity ratio. Our visualization technique allows for the simultaneous non-intrusive measurements of the temperature, deformation and velocity fields. By calculating numerically the advection of passive markers through the experimental velocity field, we found that (1) the hot center of the plume conduit only consists of fluid which has passed through the thermal boundary layer ("TBL") at the bottom of the tank from which the plume was issued. Moreover, as material is stretched by velocity gradients, it is also in the thermal boundary layer that most of the material stretching occurs (2). The fluid is then transported in the conduit without lateral mixing, and further stretched vertically by the lateral velocity gradients. Since it is only the hot upwelling plume center which melts and therefore is sampled by volcanic activity, (1) implies that the plume geochemical signature is representative of the material located in the deep TBL of the mantle from which the plume is issued. On the other hand, (2) implies that filaments, pancakes, and concentric or bimodal zonation of the plume at the surface all result from different distributions of the heterogeneities in the plume source, filaments being the most generic case. Finally, we apply the scaling laws to the case of Hawaii.

Brandeis, G.; Touitou, F.; Davaille, A.

2013-12-01

158

Areal extent of a plume of mineralized water from a flowing artesian well in Dade County, Florida  

USGS Publications Warehouse

A flowing artesian well that taps the Floridan aquifer at Chekika Hammock State Park is contaminating the overlying Biscayne aquifer with saline water. The plume of mineralized water extends approximately 7 miles southeast of the well and ranges in width from 1 to 2 miles. The areal extent of contamination in the primary plume is approximately 12 square miles. The principal ions contaminating the Biscayne aquifer are chloride, sodium, and sulfate. (USGS)

Waller, Bradley G.

1982-01-01

159

PERMEABLE REACTIVE BARRIER TECHNOLOGIES FOR CONTAMINANT REMEDIATION  

EPA Science Inventory

Environmental scientists are generally familiar with the concept of barriers for restricting the movement of contaminant plumes in ground water. Such barriers are typically constructed of highly impermeable emplacements of materials such as grouts, slurries, or sheet pilings to ...

160

Scanning thermal plumes  

Microsoft Academic Search

Over a three-year period 800 thermal line scans of power plant plumes were made by an airborne scanner, with ground truth measured concurrently at the plants. Computations using centered finite differences in the thermal scanning imagery show a lower bound in the horizontal temperature gradient in excess of 1.6 C\\/m. Gradients persist to 3 m below the surface. Vector plots

F. L. Scarpace; R. P. Madding; T. Green

1975-01-01

161

Multi-layer sampling in conventional monitoring wells for improved estimation of vertical contaminant distributions and mass  

NASA Astrophysics Data System (ADS)

"Traditional" approaches to sampling groundwater and interpreting monitoring well data often provide misleading pictures of plume shape and location in the subsurface and the true extent of contamination. Groundwater samples acquired using pumps and bailers in conventional monitoring wells yield data which are largely dependent upon the length of the screened interval, the purging and sampling method employed, and the purge volume extracted prior to sample collection. Accurate delineation of plume boundaries and vertical concentration gradients is desirable, to accurately characterize waste sites and optimize remedial strategies. The objective of this study was to compare sampling results using four different sampling approaches and devices. Conventional monitoring wells were sampled with an electric submersible pump using low-flow sampling techniques and with a bailer using "traditional" sampling methods. The same wells were also sampled with a passive multi-layer sampling system (DMLS®, Margan Ltd.). Finally, aqueous concentrations were also determined in the formation adjacent to the monitoring wells studied using a Geoprobe® and short (30 cm) screens. Results indicated that "traditional" sampling methods can provide misleading information regarding contaminant distribution and mass and indeed can miss the presence of contamination altogether.

Puls, Robert W.; Paul, Cynthia J.

1997-02-01

162

Electrochemical method for defect delineation in silicon-on-insulator wafers  

DOEpatents

An electrochemical method for defect delineation in thin-film SOI or SOS wafers in which a surface of a silicon wafer is electrically connected so as to control the voltage of the surface within a specified range, the silicon wafer is then contacted with an electrolyte, and, after removing the electrolyte, defects and metal contamination in the silicon wafer are identified.

Guilinger, Terry R. (Albuquerque, NM); Jones, Howland D. T. (Albuquerque, NM); Kelly, Michael J. (Albuquerque, NM); Medernach, John W. (Albuquerque, NM); Stevenson, Joel O. (Albuquerque, NM); Tsao, Sylvia S. (Albuquerque, NM)

1991-01-01

163

Bioremediation of contaminated groundwater  

DOEpatents

An apparatus and method for in situ remediation of contaminated subsurface soil or groundwater contaminated by chlorinated hydrocarbons. A nutrient fluid is selected to stimulate the growth and reproduction of indigenous subsurface microorganisms that are capable of degrading the contaminants; an oxygenated fluid is selected to create a generally aerobic environment for these microorganisms to degrade the contaminants, leaving only pockets that are anaerobic. The nutrient fluid is injected periodically while the oxygenated fluid is injected continuously and both are extracted so that both are drawn across the plume. The nutrient fluid stimulates microbial colony growth; withholding it periodicially forces the larger, healthy colony of microbes to degrade the contaminants. Treatment is continued until the subsurface concentration of contaminants is reduced to an acceptable, preselected level. The nutrient fluid can be methane and the oxygenated fluid air for stimulating production of methanotrophs to break down chlorohydrocarbons, especially trichloroethylene (TCE) and tetrachloroethylene.

Hazen, Terry C. (Augusta, GA); Fliermans, Carl B. (Augusta, GA)

1995-01-01

164

Bioremediation of contaminated groundwater  

DOEpatents

An apparatus and method are described for in situ remediation of contaminated subsurface soil or groundwater contaminated by chlorinated hydrocarbons. A nutrient fluid is selected to stimulate the growth and reproduction of indigenous subsurface microorganisms that are capable of degrading the contaminants. An oxygenated fluid is selected to create a generally aerobic environment for these microorganisms to degrade the contaminants, leaving only pockets that are anaerobic. The nutrient fluid is injected periodically while the oxygenated fluid is injected continuously and both are extracted so that both are drawn across the plume. The nutrient fluid stimulates microbial colony growth. Withholding it periodically forces the larger, healthy colony of microbes to degrade the contaminants. Treatment is continued until the subsurface concentration of contaminants is reduced to an acceptable, preselected level. The nutrient fluid can be methane and the oxygenated fluid air for stimulating production of methanotrophs to break down chlorohydrocarbons, especially trichloroethylene (TCE) and tetrachloroethylene. 3 figures.

Hazen, T.C.; Fliermans, C.B.

1995-01-24

165

The Green Propellant Infusion Mission Thruster Performance Testing for Plume Diagnostics  

NASA Technical Reports Server (NTRS)

The Green Propellant Infusion Mission (GPIM) is sponsored by NASA's Space Technology Mission Directorate (STMD) Technology Demonstration Mission (TDM) office. The goal of GPIM is to advance the technology readiness level of a green propulsion system, specifically, one using the monopropellant, AF-M315E, by demonstrating ground handling, spacecraft processing, and on-orbit operations. One of the risks identified for GPIM is potential contamination of sensitive spacecraft surfaces from the effluents in the plumes of AF-M315E thrusters. NASA Glenn Research Center (GRC) is conducting activities to characterize the effects of AF-M315E plume impingement and deposition. GRC has established individual plume models of the 22-N and 1-N thrusters that will be used on the GPIM spacecraft. The model simulations will be correlated with plume measurement data from Laboratory and Engineering Model 22-N, AF-M315E thrusters. The thrusters are currently being tested in a small rocket, altitude facility at NASA GRC. A suite of diagnostics, including Raman spectroscopy, Rayleigh spectroscopy, and Schlieren imaging are being used to acquire plume measurements of AF-M315E thrusters. Plume data will include temperature, velocity, relative density, and species concentration. The plume measurement data will be compared to the corresponding simulations of the plume model. The GRC effort will establish a data set of AF-M315E plume measurements and a plume model that can be used for future AF-M315E applications.

Deans, Matthew C.; Reed, Brian D.; Arrington, Lynn A.; Williams, George J.; Kojima, Jun J.; Kinzbach, McKenzie I.; McLean, Christopher H.

2014-01-01

166

Formation, Dynamics, and Impact of Plasmaspheric Plumes  

Microsoft Academic Search

Workshop on Plasmaspheric Drainage Plumes, Taos, New Mexico, 9-13 October 2006 Plasmaspheric plumes result from erosion of the plasmasphere. The Institute of Geophysics and Planetary Physics (IGPP) Workshop on Plasmaspheric Drainage Plumes was convened in Taos, N. M., on 9-13 October 2006 to examine outstanding questions about the formation and dynamics of plumes, and the impact of plumes on the

Jerry Goldstein; Joseph Borovsky; John Foster; Donald Carpenter

2007-01-01

167

Low altitude plume impingement handbook  

NASA Technical Reports Server (NTRS)

Plume Impingement modeling is required whenever an object immersed in a rocket exhaust plume must survive or remain undamaged within specified limits, due to thermal and pressure environments induced by the plume. At high altitudes inviscid plume models, Monte Carlo techniques along with the Plume Impingement Program can be used to predict reasonably accurate environments since there are usually no strong flowfield/body interactions or atmospheric effects. However, at low altitudes there is plume-atmospheric mixing and potential large flowfield perturbations due to plume-structure interaction. If the impinged surface is large relative to the flowfield and the flowfield is supersonic, the shock near the surface can stand off the surface several exit radii. This results in an effective total pressure that is higher than that which exists in the free plume at the surface. Additionally, in two phase plumes, there can be strong particle-gas interaction in the flowfield immediately ahead of the surface. To date there have been three levels of sophistication that have been used for low altitude plume induced environment predictions. Level 1 calculations rely on empirical characterizations of the flowfield and relatively simple impingement modeling. An example of this technique is described by Piesik. A Level 2 approach consists of characterizing the viscous plume using the SPF/2 code or RAMP2/LAMP and using the Plume Impingement Program to predict the environments. A Level 3 analysis would consist of using a Navier-Stokes code such as the FDNS code to model the flowfield and structure during a single calculation. To date, Level 1 and Level 2 type analyses have been primarily used to perform environment calculations. The recent advances in CFD modeling and computer resources allow Level 2 type analysis to be used for final design studies. Following some background on low altitude impingement, Level 1, 2, and 3 type analysis will be described.

Smith, Sheldon D.

1991-01-01

168

43 CFR 3922.40 - Tract delineation.  

Code of Federal Regulations, 2011 CFR

...DEPARTMENT OF THE INTERIOR RANGE MANAGEMENT (4000) OIL SHALE LEASING Application Processing § 3922.40 Tract...competitive sale to provide for the orderly development of the oil shale resource. (b) The BLM may delineate more or...

2011-10-01

169

43 CFR 3922.40 - Tract delineation.  

Code of Federal Regulations, 2014 CFR

...DEPARTMENT OF THE INTERIOR MINERALS MANAGEMENT (3000) OIL SHALE LEASING Application Processing § 3922.40 Tract...competitive sale to provide for the orderly development of the oil shale resource. (b) The BLM may delineate more or...

2014-10-01

170

43 CFR 3922.40 - Tract delineation.  

Code of Federal Regulations, 2013 CFR

...DEPARTMENT OF THE INTERIOR MINERALS MANAGEMENT (3000) OIL SHALE LEASING Application Processing § 3922.40 Tract...competitive sale to provide for the orderly development of the oil shale resource. (b) The BLM may delineate more or...

2013-10-01

171

43 CFR 3922.40 - Tract delineation.  

Code of Federal Regulations, 2012 CFR

...DEPARTMENT OF THE INTERIOR MINERALS MANAGEMENT (3000) OIL SHALE LEASING Application Processing § 3922.40 Tract...competitive sale to provide for the orderly development of the oil shale resource. (b) The BLM may delineate more or...

2012-10-01

172

Upwelling relaxation and estuarine plumes  

NASA Astrophysics Data System (ADS)

After coastal upwelling, the water properties in the nearshore coastal region close to estuaries is determined by the race between the new estuarine plume traveling along the coast and the upwelled front (a marker for the old upwelled plume and the coastal pycnocline) returning to the coast under downwelling winds. Away from an estuary, downwelling winds can return the upwelled front to the coast bringing less dense water nearshore. Near the estuary, the estuarine plume can arrive along the coast and return less dense water to the nearshore region before the upwelled front returns to the coast. Where the plume brings less dense water to the coast first, the plume keeps the upwelled front from returning to the coast. In this region, only the plume and the anthropogenic input and larvae associated with the plume waters influence the nearshore after upwelling. We quantify the extent of the region where the plume is responsible for bringing less dense water to the nearshore and keeping the upwelled front from returning to the coast after upwelling. We successfully tested our predictions against numerical experiments and field observations of the Chesapeake plume near Duck, North Carolina. We argue that this alongshore region exists for other estuaries where the time-integrated upwelling and downwelling wind stresses are comparable.

Rao, Shivanesh; Pringle, James; Austin, Jay

2011-09-01

173

Hybrid plume plasma rocket  

NASA Technical Reports Server (NTRS)

A technique for producing thrust by generating a hybrid plume plasma exhaust is disclosed. A plasma flow is generated and introduced into a nozzle which features one or more inlets positioned to direct a flow of neutral gas about the interior of the nozzle. When such a neutral gas flow is combined with the plasma flow within the nozzle, a hybrid plume is constructed including a flow of hot plasma along the center of the nozzle surrounded by a generally annular flow of neutral gas, with an annular transition region between the pure plasma and the neutral gas. The temperature of the outer gas layer is below that of the pure plasma and generally separates the pure plasma from the interior surfaces of the nozzle. The neutral gas flow both insulates the nozzle wall from the high temperatures of the plasma flow and adds to the mass flow rate of the hybrid exhaust. The rate of flow of neutral gas into the interior of the nozzle may be selectively adjusted to control the thrust and specific impulse of the device.

Chang, Franklin R. (inventor)

1989-01-01

174

(Environmental investigation of ground water contamination at Wright-Patterson Air Force Base, Ohio)  

SciTech Connect

In April 1990, Wright-Patterson Air Force Base (WPAFB) initiated an effort for the evaluation of potential removal of ground water contamination at the Base. This report presents a current assessment of the nature and extent of the contamination believed to be migrating across the southwestern boundary of Area C and the northern boundary of Area B based upon analysis of existing environmental data obtained from several sources. The existing data base indicates widespread, low-level contamination moving across Base boundaries at levels that pose no immediate threat to the Mad River Valley well fields. An investigation by the City of Dayton in May and June 1990, however, implies that a more identifiable plume of PCE and TCE may be crossing the southwestern boundary of Area C immediately downgradient of Landfill 5. More data is needed to delineate ground water contamination and to design and implement a suitable control system. This report concludes that although an extensive study of the boundaries in question would be the preferred approach, a limited, focused investigation and subsequent feasibility study can be accomplished with a reasonable certainty of achieving the desired outcome of this project.

Not Available

1991-10-01

175

The Ultraviolet Plume Instrument (UVPI)  

Microsoft Academic Search

The Ultraviolet Plume Instrument (UVPI) was launched aboard the Low-power Atmospheric Compensation Experiment (LACE) satellite on 14 Feb. 1990. Both the spacecraft and the UVPI were sponsored by the Directed Energy Office of the Strategic Defense Initiative Organization. The mission of the UVPI was to obtain radiometrically calibrated images of rocket plumes at high altitude and background image data of

D. M. Horan

1993-01-01

176

Atmospheric chemistry in volcanic plumes  

PubMed Central

Recent field observations have shown that the atmospheric plumes of quiescently degassing volcanoes are chemically very active, pointing to the role of chemical cycles involving halogen species and heterogeneous reactions on aerosol particles that have previously been unexplored for this type of volcanic plumes. Key features of these measurements can be reproduced by numerical models such as the one employed in this study. The model shows sustained high levels of reactive bromine in the plume, leading to extensive ozone destruction, that, depending on plume dispersal, can be maintained for several days. The very high concentrations of sulfur dioxide in the volcanic plume reduces the lifetime of the OH radical drastically, so that it is virtually absent in the volcanic plume. This would imply an increased lifetime of methane in volcanic plumes, unless reactive chlorine chemistry in the plume is strong enough to offset the lack of OH chemistry. A further effect of bromine chemistry in addition to ozone destruction shown by the model studies presented here, is the oxidation of mercury. This relates to mercury that has been coemitted with bromine from the volcano but also to background atmospheric mercury. The rapid oxidation of mercury implies a drastically reduced atmospheric lifetime of mercury so that the contribution of volcanic mercury to the atmospheric background might be less than previously thought. However, the implications, especially health and environmental effects due to deposition, might be substantial and warrant further studies, especially field measurements to test this hypothesis. PMID:20368458

von Glasow, Roland

2010-01-01

177

Stationary plasma thruster plume characteristics  

Microsoft Academic Search

Stationary Plasma Thrusters (SPT's) are being investigated for application to a variety of near-term missions. This paper presents the results of a preliminary study of the thruster plume characteristics which are needed to assess spacecraft integration requirements. Langmuir probes, planar probes, Faraday cups, and a retarding potential analyzer were used to measure plume properties. For the design operating voltage of

Roger M. Myers; David H. Manzella

1994-01-01

178

Mantle plumes and flood basalts  

Microsoft Academic Search

We discuss the geological, geophysical, and petrological observations that constrain the nature of mantle convection in plumes, and show how theoretical models of mantle plumes have developed over the past three decades. The large volumes of lava emplaced in geologically short periods as flood basalts are generated mainly by decompression melting of abnormally hot mantle brought to the base of

R. S. White; D. P. Mckenzie

1995-01-01

179

USING DIRECT-PUSH TOOLS TO MAP HYDROSTRATIGRAPHY AND PREDICT MTBE PLUME DIVING  

EPA Science Inventory

Conventional wells for monitoring MTBE contamination at underground storage tank sites are screened a few feet above and a few feet below the water table. At some sites, a plume of contamination in ground water may dive below the screen of conventional monitoring wells and escap...

180

Evidence of Residual Plasmaspheric Plumes  

NASA Astrophysics Data System (ADS)

Plasmaspheric erosion produces plumes of plasma that extend sunward from the main torus. When geomagnetic activity decreases, a given plume loses its sunward orientation, rotating eastward and wrapping itself around the plasmasphere torus. The residual plume is a major feature of the recovery phase plasmasphere, and is suspected to be an important influence upon the loss rates of energetic particles. In this study, comparison between in situ observations of the Los Alamos National Laboratory (LANL) Magnetospheric Plasma Analyzers (MPA) and output of a plasmapause test particle (PTP) simulation for the moderately disturbed interval 18--20 January 2000 reveals evidence of plasmaspheric plumes that wrapped completely around the main torus and lasted for at least 40 hours and possibly as long as 60 hours. The presence of long-lived multiple wrapped residual plumes suggests that the global plasmaspheric density distribution preserves some memory of prior epochs of erosion and recovery.

Goldstein, J.; Thomsen, M.

2007-12-01

181

Possible Causes of Decreasing Benzene Concentrations in an Oil-Contaminated Aquifer  

Microsoft Academic Search

Crude oil contamination from a 1979 oil spill near Bemidji, Minnesota resulted in a subsurface oil body and a dissolved hydrocarbon plume in the groundwater. Benzene concentrations in the plume adjacent to the oil decreased from nearly 5 mg\\/L in 1993 to less than 3 mg\\/L in 2007. Benzene depletion within the plume and oil body was investigated with a

D. Drennan; B. A. Bekins; E. Warren; M. J. Baedecker; R. P. Eganhouse

2010-01-01

182

Automatic delineation of body contours on cone-beam CT images using a delineation booster.  

PubMed

In radiotherapy, cone-beam computerized tomography (CBCT) scans are used for position correction for various tumour sites. At the start of the treatment, a CT scan that serves as input for a treatment planning is acquired. A CBCT scan is made prior to the irradiation of the tumour. Because there might be significant interfractional tumour movement, online recalculation of the dose improves decision making on how to proceed. A prerequisite for such recalculation is an accurately delineated body contour. In this note, we present an automatic delineation method for the body contour in the unprocessed CBCT scans, that employs a novel delineation boosting technique. The main idea of this technique is to construct an accurate delineation by combining the strength of several edge detectors in an innovative way. Quantitative validation reveals that the algorithm performs comparably with the manual delineations of two trained observers. Furthermore, because of the generic nature of the delineation boosting procedure, the algorithm can easily be extended with additional edge detectors to further increase the accuracy. Finally, the processing time of one scan when delineated manually is 3 h, and the total processing time is 24 min for one scan if the algorithm is used in its present form. Current investigation includes the conversion of the Matlab algorithm to C++ and the development of a visual tool to quickly detect which automatically delineated slices need manual correction. From this we expect further speeding up of the process, allowing online computation. PMID:22706031

Stippel, G; van Rooijen, D C; Crezee, J; Bel, A

2012-07-01

183

Ion Engine Plume Interaction Calculations for Prototypical Prometheus 1  

NASA Technical Reports Server (NTRS)

Prometheus 1 is a conceptual mission to demonstrate the use of atomic energy for distant space missions. The hypothetical spacecraft design considered in this paper calls for multiple ion thrusters, each with considerably higher beam energy and beam current than have previously flown in space. The engineering challenges posed by such powerful thrusters relate not only to the thrusters themselves, but also to designing the spacecraft to avoid potentially deleterious effects of the thruster plumes. Accommodation of these thrusters requires good prediction of the highest angle portions of the main beam, as well as knowledge of clastically scattered and charge exchange ions, predictions for grid erosion and contamination of surfaces by eroded grid material, and effects of the plasma plume on radio transmissions. Nonlinear interactions of multiple thrusters are also of concern. In this paper we describe two- and three-dimensional calculations for plume structure and effects of conceptual Prometheus 1 ion engines. Many of the techniques used have been validated by application to ground test data for the NSTAR and NEXT ion engines. Predictions for plume structure and possible sputtering and contamination effects will be presented.

Mandell, Myron J.; Kuharski, Robert A.; Gardner, Barbara M.; Katz, Ira; Randolph, Tom; Dougherty, Ryan; Ferguson, Dale C.

2005-01-01

184

The Impact of Well-Field Configuration on Plume Persistence  

NASA Astrophysics Data System (ADS)

It is now recognized that most sites with large groundwater contaminant plumes will require many decades before cleanup will be achieved under current methods and standards. Conceptually, the factors that contribute to plume persistence have long been established, including uncontrolled source zones, dispersed reservoirs of dissolved (present in lower-permeability zones) and sorbed contaminant, and hydraulic-related factors such as non-optimal remedial well-field performance. Of these potential factors, hydraulic phenomena associated with configuration and operation of the well field employed for remedial operations have received minimal attention. The objective of this research is to investigate the influence of well-field configuration on contaminant mass removal and reduction in contaminant mass discharge (CMD). Mathematical modeling, implemented using MODFLOW and MT3D, was conducted to simulate scenarios with different well-field configurations in both homogenous and heterogeneous aquifers. The system was designed such that contaminant was present as only aqueous and sorbed mass (no separate organic-liquid sources). The impacts of several variables on the results are investigated, including pumping rate, layer thickness, and vertical dispersivity. The results are assessed in terms of the relationship between reductions in CMD and reductions in contaminant mass.

Guo, Z.; Brusseau, M.

2013-12-01

185

Quantifying and Predicting Reactive Transport of Uranium in Waste Plumes  

SciTech Connect

The Hanford Site is the DOE's largest legacy waste site, with uranium (U) from plutonium processing being a major contaminant in its subsurface. Accident release of highly concentrated high level wastes (e.g. 0.5 lb U(VI)/gal) left large quantities of U in the vadose zone under tank farms (e.g. 7-8 tons U(VI) under tank BX-102 (Jones et al., 2001)). The U contamination has been found in groundwater in both 300 and 200 Areas of Hanford, indicating U(VI) was/is mobile. Because excavation costs are enormous, this U will likely be left in-ground for the foreseeable future. Therefore, understanding the contamination processes and the resulting U spatial and temporary distributions and mobility in the heavily contaminated Hanford site is needed in order to forecast its future transport. The overall objective of this research is to develop an experimentally supported conceptual model of U reactive transport, during and after the tank leakage, at heavily U-contaminated areas of the Hanford vadose zone. The conceptual model will incorporate key geochemical and physical controls on the contamination process, explain the current distribution of U in the vadose zone, and guide predictions of its future mobility under the influence of natural recharge. We do not seek to predict the complex flow geometry of any specific waste plume. Instead, our work is trying to identify the hierarchy of processes relevant along U waste plume paths.

Wan Jiamin; Tokunaga, Tetsu; Steefel, Carl; Burns, Peter

2005-06-01

186

Pulsed Plasma Thruster Contamination  

NASA Technical Reports Server (NTRS)

Pulsed Plasma Thrusters (PPT's) are currently baselined for the Air Force Mightysat II.1 flight in 1999 and are under consideration for a number of other missions for primary propulsion, precision positioning, and attitude control functions. In this work, PPT plumes were characterized to assess their contamination characteristics. Diagnostics included planar and cylindrical Langmuir probes and a large number of collimated quartz contamination sensors. Measurements were made using a LES 8/9 flight PPT at 0.24, 0.39, 0.55, and 1.2 m from the thruster, as well as in the backflow region behind the thruster. Plasma measurements revealed a peak centerline ion density and velocity of approx. 6 x 10(exp 12) cm(exp -3) and 42,000 m/s, respectively. Optical transmittance measurements of the quartz sensors after 2 x 10(exp 5) pulses showed a rapid decrease in plume contamination with increasing angle from the plume axis, with a barely measurable transmittance decrease in the ultraviolet at 90 deg. No change in optical properties was detected for sensors in the backflow region.

Myers, Roger M.; Arrington, Lynn A.; Pencil, Eric J.; Carter, Justin; Heminger, Jason; Gatsonis, Nicolas

1996-01-01

187

Empirical Characterization of Plasmaspheric Plumes  

NASA Astrophysics Data System (ADS)

The formation and subsequent development of plasmaspheric plumes in a given convection event is well characterized by a series of distinct phases, each triggered by a change in the strength of global magnetospheric convection. For example, after a prolonged quiet period, an increase in convection strength triggers erosion, and the formation of a sunward-pointing plume that typically spans at least a few hours of dayside magnetic local time (MLT). On the other hand, a convection decrease causes a pre-existing plume to begin rotating eastward, eventually becoming wrapped around the main plasmaspheric torus. Predicted by computational models, plume phases have since proven to be a consistent feature of plasmaspheric dynamics in numerous observations made by the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) spacecraft during the years 2000-2005. However, currently-existing empirical models for the plasmasphere do not include plumes or plume phases. We present first results of an empirical model of plume density and location using (respectively) measurements by the IMAGE radio plasma imager (RPI) and extreme ultraviolet (EUV) instruments. This new model framework differs differs from current models in two ways. First, it represents the plasmapause as a multi-valued function of L versus MLT. Second, it incorporates the concept of plume phases by parameterizing plasmaspheric density based on superposed epoch analysis. An empirical characterization of plasmaspheric plume density and location is an important step toward better knowledge of the spatial and temporal dependence of critical wave-particle interactions affecting ring current ions and outer radiation belt electrons.

Goldstein, J.; Denton, R. E.; Sandel, B. R.

2008-12-01

188

A simple method for calculating growth rates of petroleum hydrocarbon plumes  

USGS Publications Warehouse

Consumption of aquifer Fe(III) during biodegradation of ground water contaminants may result in expansion of a contaminant plume, changing the outlook for monitored natural attenuation. Data from two research sites contaminated with petroleum hydrocarbons show that toluene and xylenes degrade under methanogenic conditions, but the benzene and ethylbenzene plumes grow as aquifer Fe(III) supplies are depleted. By considering a one-dimensional reaction front in a constant unidirectional flow field, it is possible to derive a simple expression for the growth rate of a benzene plume. The method balances the mass flux of benzene with the Fe(III) content of the aquifer, assuming that the biodegradation reaction is instantaneous. The resulting expression shows that the benzene front migration is retarded relative to the ground water velocity by a factor that depends on the concentrations of hydrocarbon and bioavailable Fe(III). The method provides good agreement with benzene plumes at a crude oil study site in Minnesota and a gasoline site in South Carolina. Compared to the South Carolina site, the Minnesota site has 25% higher benzene flux but eight times the Fe(III), leading to about one-sixth the expansion rate. Although it was developed for benzene, toluene, ethylbenzene, and xylenes, the growth-rate estimation method may have applications to contaminant plumes from other persistent contaminant sources. Copyright ?? 2005 National Ground Water Association.

Bekins, B.A.; Cozzarelli, I.M.; Curtis, G.P.

2005-01-01

189

Geochemical and Mineralogical Investigation of Uranium in Multi–element Contaminated, Organic–rich Subsurface Sediment  

SciTech Connect

Alluvial sediments characterized by an abundance of refractory or lignitic organic carbon compounds and reduced Fe and S bearing mineral phases have been identified through drilling activities at the U.S. Department of Energy’s (DOE) Integrated Field Research Challenge (IFRC) site at Rifle, CO. Regions of the subsurface from which such sediments are derived are referred to as Naturally Reduced Zones (NRZ). We conducted a study with NRZ sediments with the objective to: i.) Characterize solid phase contamination of U and other co-contaminants; ii.) Document the occurrence of potential U host minerals; iii.) Determine U valence state and micron scale spatial association with co-contaminants. Macroscopic (wet chemical batch extractions and a column experiment), microscopic (SEM-EDS), and spectroscopic (Mössbauer, µ-XRF and XANES) techniques were employed. Results showed that sediments’ solid phase had significant concentrations of U, S, As, Zn, V, Cr, Cu and Se, and a remarkable assortment of potential U hosts (sorbents and/or electron donors), such as Fe oxides (hematite, magnetite, Al-substituted goethite), siderite, reduced Fe(II) bearing clays, sulfides of different types, Zn sulfide framboids and multi – element sulfides. Multi-contaminants, micron size (ca. 5 to 30 µm) areas of mainly U(IV) and some U(VI), and/or other electron scavengers or donors such as Se, As, Cr, and V were discovered in the sediments, suggesting complex micron-scale system responses to transient redox conditions, and different extent and rates of competing U redox reactions than those of single contaminant systems. Collectively, the results improve our understanding and ability to predict U and NRZ’s complex behavior and will delineate future research directions to further study both the natural attenuation and persistence of contaminant plumes and their contribution to groundwater contamination.

Qafoku, Nikolla; Gartman, Brandy N.; Kukkadapu, Ravi K.; Arey, Bruce W.; Williams, Kenneth H.; Mouser, Paula J.; Heald, Steve M.; Bargar, John R.; Janot, Noemie; Yabusaki, Steven B.; Long, Philip E.

2014-03-02

190

Small rocket exhaust plume data  

NASA Technical Reports Server (NTRS)

During recent cryodeposit tests with an 0.18-N thruster, the mass flux in the plume back field was measured for the first time for nitrogen, carbon dioxide, and a mixture of nitrogen, hydrogen, and ammonia at various inlet pressures. This mixture simulated gases that would be generated by a hydrazine plenum attitude propulsion system. The measurements furnish a base upon which to build a mathematical model of plume back flow that will be used in predicting the mass distribution in the boundary region of other plumes. The results are analyzed and compared with existing analytical predictions.

Chirivella, J. E.; Moynihan, P. I.; Simon, W.

1972-01-01

191

Assessment of natural attenuation of ground-water contamination at sites FT03, LF13, and WP14/LF15, Dover Air Force Base, Delaware  

USGS Publications Warehouse

Water-quality, aquifer-sediment, and hydro-logic data were used to assess the effectiveness of natural attenuation of ground-water contamination at Fire Training Area Three, the Rubble Area Landfill, the Liquid Waste Disposal Landfill, and the Receiver Station Landfill in the East Management Unit of Dover Air Force Base, Delaware. These sites, which are contaminated with chlorinated solvents and fuel hydrocarbons, are under-going long-term monitoring to determine if natural attenuation continues to sufficiently reduce contaminant concentrations to meet regulatory requirements. This report is the first assessment of the effectiveness of natural attenuation at these sites since long-term monitoring began in 1999, and follows a preliminary investigation done in 1995?96. This assessment was done by the U.S. Geological Survey in cooperation with the U.S. Air Force.Since 1995?96, additional information has been collected and used in the current assessment. The conclusions in this report are based primarily on ground-water samples collected from January through March 2000. Previous analytical results from selected wells, available geologic and geo-physical well logs, and newly acquired information such as sediment organic-carbon measurements, hydraulic-conductivity measurements determined from slug tests on wells in the natural attenuation study area, and water-level measurements from surficial-aquifer wells also were used in this assessment. This information was used to: (1) calculate retardation factors and estimate contaminant migration velocities, (2) improve estimates of ground-water flow directions and inferred contaminant migration pathways, (3) better define the areal extent of contamination and the proximity of contaminants to discharge areas and the Base boundary, (4) develop a better under-standing of the vertical variability of contaminant concentrations and redox conditions, (5) evaluate the effects of temporal changes on concentrations in the plumes and source areas, and (6) determine whether intrinsic biodegradation is occurring at these sites.The water-quality data indicate that intrinsic biodegradation is occurring at all three sites. The strongest indication of intrinsic biodegradation is the detection of tetrachloroethene and trichloroethene breakdown products within and down-gradient of the source areas. The patterns of electron acceptors and metabolic by-products indicate that contaminant biodegradation has changed the prevailing geochemistry of the surficial aquifer, creating the strongly reducing conditions necessary for chlorinated solvent bio-degradation. Geochemical changes include depleted dissolved oxygen and elevated ferrous iron and methane levels relative to concentrations in uncontaminated zones of the surficial aquifer. At Fire Training Area Three and the Rubble Area Landfill sites, natural attenuation appears to be adequate for controlling the migration of the contaminant plumes. At the third site, the Liquid Waste Disposal and Receiver Station Landfills, the plume is larger and the uncertainty about the effectiveness of natural attenuation in reducing contaminant concentrations and controlling plume migration is greater. Ground-water data indicate, however, that U.S. Environmental Protection Agency maximum contaminant levels were not exceeded in any point-of-compliance wells located along the Base boundary.The information presented in this report led to the development of improved conceptual models for these sites, and to the recognition of four issues that are currently unclear and may need further study. These issues include delineating the areal and vertical extent of the contaminant plumes in greater detail, determining the extent of intrinsic biodegradation downgradient of the Liquid Waste Disposal and Receiver Station Landfills, deter-mining the fate of contaminants in the ground-water discharge areas, and determining the effect of temporal variability in source concentrations and ground-water

Barbaro, Jeffrey R.

2002-01-01

192

Space shuttle exhaust plumes in the lower thermosphere: Advective transport and diffusive spreading  

NASA Astrophysics Data System (ADS)

The space shuttle main engine plume deposited between 100 and 115 km altitude is a valuable tracer for global-scale dynamical processes. Several studies have shown that this plume can reach the Arctic or Antarctic to form bursts of polar mesospheric clouds (PMCs) within a few days. The rapid transport of the shuttle plume is currently not reproduced by general circulation models and is not well understood. To help delineate the issues, we present the complete satellite datasets of shuttle plume observations by the Sounding of the Atmosphere using Broadband Emission Radiometry instrument and the Sub-Millimeter Radiometer instrument. From 2002 to 2011 these two instruments observed 27 shuttle plumes in over 600 limb scans of water vapor emission, from which we derive both advective meridional transport and diffusive spreading. Each plume is deposited at virtually the same place off the United States east coast so our results are relevant to northern mid-latitudes. We find that the advective transport for the first 6-18 h following deposition depends on the local time (LT) of launch: shuttle plumes deposited later in the day (~13-22 LT) typically move south whereas they otherwise typically move north. For these younger plumes rapid transport is most favorable for launches at 6 and 18 LT, when the displacement is 10° in latitude corresponding to an average wind speed of 30 m/s. For plumes between 18 and 30 h old some show average sustained meridional speeds of 30 m/s. For plumes between 30 and 54 h old the observations suggest a seasonal dependence to the meridional transport, peaking near the beginning of year at 24 m/s. The diffusive spreading of the plume superimposed on the transport is on average 23 m/s in 24 h. The plume observations show large variations in both meridional transport and diffusive spreading so that accurate modeling requires knowledge of the winds specific to each case. The combination of transport and spreading from the STS-118 plume in August 2007 formed bright PMCs between 75 and 85°N a day after launch. These are the highest latitude Arctic PMCs formed by shuttle exhaust reported to date.

Stevens, Michael H.; Lossow, Stefan; Siskind, David E.; Meier, R. R.; Randall, Cora E.; Russell, James M.; Urban, Jo; Murtagh, Donal

2014-02-01

193

COMPARING AND LINKING PLUMES ACROSS MODELING APPROACHES  

EPA Science Inventory

River plumes carry many pollutants, including microorganisms, into lakes and the coastal ocean. The physical scales of many stream and river plumes often lie between the scales for mixing zone plume models, such as the EPA Visual Plumes model, and larger-sized grid scales for re...

194

A Fully Automated Sea Boundary Delineator  

Microsoft Academic Search

Although the problem addressed in this paper may arise on land, it is typically found in a maritime context, when one is trying to determine the limits of the Territorial Sea, Extended Zone and Economic Exclusion Zone, as well as the so-called Median and Equidistant Lines. To delineate on a map the boundaries of those zones, that is, to trace

Albert H. J. CHRISTENSEN

2002-01-01

195

Stochastic delineation of well capture zones  

Microsoft Academic Search

In this work, we describe a stochastic method for delineating well capture zones in randomly heterogeneous porous media. We use a moment equation (ME) approach to derive the time-dependent mean capture zones and their associated uncertainties. The mean capture zones are determined by reversely tracking the non-reactive particles released at a small circle around each pumping well. The uncertainty associated

D. X. Zhang; Z. M. Lu

2004-01-01

196

Ground Water Contamination  

NSDL National Science Digital Library

This detailed discussion explains that most ground water contamination is the result of human activity, and that several laws have been passed with an aim to minimize effects. The Clean Water Act and the Safe Drinking Water Act are explained along with the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA, or Superfund), the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), the Resource Conservation and Recovery Act (RCRA), and the Toxic Substances Control Act (TSCA). Other terms explained include zone of contribution, interaquifer leakage, and plume of contamination. Special tables included at this site are Typical Sources of Potential Ground Water Contamination by Land Use Category and Potential Harmful Components of Common Household Products. There is also a full page diagram showing some potential sources of ground water contamination.

197

IMPROVED PREDICTION OF BENDING PLUMES  

EPA Science Inventory

Integral plume models harbor a fundamental, often significant error because the standard implementation of control volumes, or elements, is inconsistent with the overall geometry of the problem. he error, called negative volume anomaly, occurs irregularly, being contingent on the...

198

NSTAR Ion Thruster Plume Impact Assessments  

NASA Technical Reports Server (NTRS)

Tests were performed to establish 30-cm ion thruster plume impacts, including plume characterizations via near and farfield ion current measurements, contamination, and sputtering assessments. Current density measurements show that 95% of the beam was enclosed within a 22 deg half-angle and that the thrust vector shifted by less than 0.3 deg during throttling from 2.3 to 0.5 kW. The beam flatness parameter was found to be 0.47, and the ratio of doubly charged to singly charged ion current density decreased from 15% at 2.3 kW to 5% at 0.5 kW. Quartz sample erosion measurements showed that the samples eroded at a rate of between 11 and 13 pm/khr at 25 deg from the thruster axis, and that the rate dropped by a factor of four at 40 deg. Good agreement was obtained between extrapolated current densities and those calculated from tantalum target erosion measurements. Quartz crystal microbalance and witness plate measurements showed that ion beam sputtering of the tank resulted in a facility material backflux rate of -10 A/hr in a large space simulation chamber.

Myers, Roger M.; Pencil, Eric J.; Rawlin, Vincent K.; Kussmaul, Michael; Oden, Katessha

1995-01-01

199

Overview of NASA GRCs Green Propellant Infusion Mission Thruster Testing and Plume Diagnostics  

NASA Technical Reports Server (NTRS)

The Green Propellant Infusion Mission (GPIM) is sponsored by NASA's Space Technology Mission Directorate (STMD) Technology Demonstration Mission (TDM) office. The goal of GPIM is to advance the technology readiness level of a green propulsion system, specifically, one using the monopropellant, AF-M315E, by demonstrating ground handling, spacecraft processing, and on-orbit operations. One of the risks identified for GPIM is potential contamination of sensitive spacecraft surfaces from the effluents in the plumes of AF-M315E thrusters. NASA Glenn Research Center (GRC) is conducting activities to characterize the effects of AF-M315E plume impingement and deposition. GRC has established individual plume models of the 22-N and 1-N thrusters that will be used on the GPIM spacecraft. The models describe the pressure, temperature, density, Mach number, and species concentration of the AF-M315E thruster exhaust plumes. The models are being used to assess the impingement effects of the AF-M315E thrusters on the GPIM spacecraft. The model simulations will be correlated with plume measurement data from Laboratory and Engineering Model 22-N, AF-M315E thrusters. The thrusters will be tested in a small rocket, altitude facility at NASA GRC. The GRC thruster testing will be conducted at duty cycles representatives of the planned GPIM maneuvers. A suite of laser-based diagnostics, including Raman spectroscopy, Rayleigh spectroscopy, Schlieren imaging, and physical probes will be used to acquire plume measurements of AFM315E thrusters. Plume data will include temperature, velocity, relative density, and species concentration. The plume measurement data will be compared to the corresponding simulations of the plume model. The GRC effort will establish a data set of AF-M315E plume measurements and a plume model that can be used for future AF-M315E applications.

Deans, Matthew C.; Reed, Brian D.; Yim, John T.; Arrington, Lynn A.; Williams, George J.; Kojima, Jun J.; McLean, Christopher H.

2014-01-01

200

Hot rocket plume experiment - Survey and conceptual design. [of rhenium-iridium bipropellants  

NASA Technical Reports Server (NTRS)

Attention is given to a space-borne engine plume experiment study to fly an experiment which will both verify and quantify the reduced contamination from advanced rhenium-iridium earth-storable bipropellant rockets (hot rockets) and provide a correlation between high-fidelity, in-space measurements and theoretical plume and surface contamination models. The experiment conceptual design is based on survey results from plume and contamination technologists throughout the U.S. With respect to shuttle use, cursory investigations validate Hitchhiker availability and adaptability, adequate remote manipulator system (RMS) articulation and dynamic capability, acceptable RMS attachment capability, adequate power and telemetry capability, and adequate flight altitude and attitude/orbital capability.

Millard, Jerry M.; Luan, Taylor W.; Dowdy, Mack W.

1992-01-01

201

[Environmental investigation of ground water contamination at Wright-Patterson Air Force Base, Ohio]. Volume 1, Site assessment report  

SciTech Connect

In April 1990, Wright-Patterson Air Force Base (WPAFB) initiated an effort for the evaluation of potential removal of ground water contamination at the Base. This report presents a current assessment of the nature and extent of the contamination believed to be migrating across the southwestern boundary of Area C and the northern boundary of Area B based upon analysis of existing environmental data obtained from several sources. The existing data base indicates widespread, low-level contamination moving across Base boundaries at levels that pose no immediate threat to the Mad River Valley well fields. An investigation by the City of Dayton in May and June 1990, however, implies that a more identifiable plume of PCE and TCE may be crossing the southwestern boundary of Area C immediately downgradient of Landfill 5. More data is needed to delineate ground water contamination and to design and implement a suitable control system. This report concludes that although an extensive study of the boundaries in question would be the preferred approach, a limited, focused investigation and subsequent feasibility study can be accomplished with a reasonable certainty of achieving the desired outcome of this project.

Not Available

1991-10-01

202

Elements in cottonwood trees as an indicator of ground water contaminated by landfill leachate  

Microsoft Academic Search

Ground water at the Normal Landfill Research Site is contaminated by a leachate plume emanating from a closed, unlined landfill formerly operated by the city of Norman, Oklahoma. Ground water contaminated by the leachate plume is known to be elevated in the concentration of many organic and inorganic constituents. Specific conductance, alkalinity, chloride, dissolved organic carbon, boron, sodium, strontium, and

James A. Erdman; Scott Christenson

2000-01-01

203

Active Volcanic Plumes on Io  

NASA Technical Reports Server (NTRS)

This color image, acquired during Galileo's ninth orbit around Jupiter, shows two volcanic plumes on Io. One plume was captured on the bright limb or edge of the moon (see inset at upper right), erupting over a caldera (volcanic depression) named Pillan Patera after a South American god of thunder, fire and volcanoes. The plume seen by Galileo is 140 kilometers (86 miles) high and was also detected by the Hubble Space Telescope. The Galileo spacecraft will pass almost directly over Pillan Patera in 1999 at a range of only 600 kilometers (373 miles).

The second plume, seen near the terminator (boundary between day and night), is called Prometheus after the Greek fire god (see inset at lower right). The shadow of the 75-kilometer (45- mile) high airborne plume can be seen extending to the right of the eruption vent. The vent is near the center of the bright and dark rings. Plumes on Io have a blue color, so the plume shadow is reddish. The Prometheus plume can be seen in every Galileo image with the appropriate geometry, as well as every such Voyager image acquired in 1979. It is possible that this plume has been continuously active for more than 18 years. In contrast, a plume has never been seen at Pillan Patera prior to the recent Galileo and Hubble Space Telescope images.

North is toward the top of the picture. The resolution is about 6 kilometers (3.7 miles) per picture element. This composite uses images taken with the green, violet and near infrared filters of the solid state imaging (CCD) system on NASA's Galileo spacecraft. The images were obtained on June 28, 1997, at a range of more than 600,000 kilometers (372,000 miles).

The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at URL http://www.jpl.nasa.gov/galileo/sepo

1997-01-01

204

The Structure and Origin of Solar Plumes: Network Plumes  

NASA Astrophysics Data System (ADS)

This study is based upon plumes seen close to the solar limb within coronal holes in the emission from ions formed in the temperature region of 1 MK, in particular, the band of Fe IX 171 Å from EIT on the Solar and Heliospheric Observatory. It is shown, using geometric arguments, that two distinct classes of structure contribute to apparently similar plume observations. Quasi-cylindrical structures are anchored in discrete regions of the solar surface (beam plumes), and faint extended structures require integration along the line of sight (LOS) in order to reproduce the observed brightness. This second category, sometimes called "curtains," are ubiquitous within the polar holes and are usually more abundant than the beam plumes, which depend more on the enhanced magnetic structures detected at their footpoints. It is here proposed that both phenomena are based on plasma structures in which emerging magnetic loops interact with ambient monopolar fields, involving reconnection. The important difference is in terms of physical scale. It is proposed that curtains are composed of a large number of microplumes, distributed along the LOS. The supergranule network provides the required spatial structure. It is shown by modeling that the observations can be reproduced if microplumes are concentrated within some 5 Mm of the cell boundaries. For this reason, we propose to call this second population "network plumes." The processes involved could represent a major contribution to the heating mechanism of the solar corona.

Gabriel, A.; Bely-Dubau, F.; Tison, E.; Wilhelm, K.

2009-07-01

205

Delineation of fault zones using imaging radar  

NASA Technical Reports Server (NTRS)

The assessment of earthquake hazards and mineral and oil potential of a given region requires a detailed knowledge of geological structure, including the configuration of faults. Delineation of faults is traditionally based on three types of data: (1) seismicity data, which shows the location and magnitude of earthquake activity; (2) field mapping, which in remote areas is typically incomplete and of insufficient accuracy; and (3) remote sensing, including LANDSAT images and high altitude photography. Recently, high resolution radar images of tectonically active regions have been obtained by SEASAT and Shuttle Imaging Radar (SIR-A and SIR-B) systems. These radar images are sensitive to terrain slope variations and emphasize the topographic signatures of fault zones. Techniques were developed for using the radar data in conjunction with the traditional types of data to delineate major faults in well-known test sites, and to extend interpretation techniques to remote areas.

Toksoz, M. N.; Gulen, L.; Prange, M.; Matarese, J.; Pettengill, G. H.; Ford, P. G.

1986-01-01

206

Delineation, characterization, and classification of topographic eminences  

NASA Astrophysics Data System (ADS)

Topographic eminences are defined as upwardly rising, convex shaped topographic landforms that are noticeably distinct in their immediate surroundings. As opposed to everyday objects, the properties of a topographic eminence are dependent not only on how it is conceptualized, but is also intrinsically related to its spatial extent and its relative location in the landscape. In this thesis, a system for automated detection, delineation and characterization of topographic eminences based on an analysis of digital elevation models is proposed. Research has shown that conceptualization of eminences (and other landforms) is linked to the cultural and linguistic backgrounds of people. However, the perception of stimuli from our physical environment is not subject to cultural or linguistic bias. Hence, perceptually salient morphological and spatial properties of the natural landscape can form the basis for generically applicable detection and delineation of topographic eminences. Six principles of cognitive eminence modeling are introduced to develop the philosophical foundation of this research regarding eminence delineation and characterization. The first step in delineating eminences is to automatically detect their presence within digital elevation models. This is achieved by the use of quantitative geomorphometric parameters (e.g., elevation, slope and curvature) and qualitative geomorphometric features (e.g., peaks, passes, pits, ridgelines, and valley lines). The process of eminence delineation follows that of eminence detection. It is posited that eminences may be perceived either as monolithic terrain objects, or as composites of morphological parts (e.g., top, bottom, slope). Individual eminences may also simultaneously be conceived as comprising larger, higher order eminence complexes (e.g., mountain ranges). Multiple algorithms are presented for the delineation of simple and complex eminences, and the morphological parts of eminences. The proposed eminence detection and delineation methods are amenable to intuitive parameterization such that they can easily capture the multitude of eminence conceptualizations that people develop due to differences in terrain type and cultural and linguistic backgrounds. Eminence delineation is an important step in object based modeling of the natural landscape. However, mere 'geocoding' of eminences is not sufficient for modeling how people intuitively perceive and reason about eminences. Therefore, a comprehensive eminence parameterization system for characterizing the perceptual properties of eminences is also proposed in this thesis. Over 40 parameters are suggested for measuring the commonly perceived properties of eminences: size, shape, topology, proximity, and visibility. The proposed parameters describe different aspects of naive eminence perception. Quantitative analysis of eminence parameters using cluster analysis, confirms that not only can eminences be parameterized as individual terrain objects, but that eminence (dis)similarities can be exploited to develop intuitive eminence classification systems. Eminence parameters are also shown to be essential for exploring the relationships between extracted eminences and natural language terms (e.g., hill, mount, mountain, peak) used commonly to refer to different types of eminences. The results from this research confirm that object based modeling of the landscape is not only useful for terrain information system design, but is also essential for understanding how people commonly conceptualize their observations of and interactions with the natural landscape.

Sinha, Gaurav

207

Hyperspectral chemical plume quantification and temperature estimation  

NASA Astrophysics Data System (ADS)

Most hyperspectral chemical gaseous plume quantification algorithms assume a priori knowledge of the plume temperature either through direct measurement or an auxiliary temperature estimation approach. In this paper, we propose a new quantification algorithm that can simultaneously estimate the plume strength as well as its temperature. We impose only a mild spatial assumption, that at least one nearby pixel shares the same plume parameters as the target pixel, which we believe will be generally satisfied in practice. Simulations show that the performance loss incurred by estimating both the temperature and plume strength is small, as compared to the case when the plume temperature is known exactly.

Niu, Sidi; Golowich, Steven E.; Ingle, Vinay K.; Manolakis, Dimitris G.

2014-06-01

208

Stationary Plasma Thruster Plume Characteristics  

NASA Technical Reports Server (NTRS)

Stationary Plasma Thrusters (SPT's) are being investigated for application to a variety of near-term missions. This paper presents the results of a preliminary study of the thruster plume characteristics which are needed to assess spacecraft integration requirements. Langmuir probes, planar probes, Faraday cups, and a retarding potential analyzer were used to measure plume properties. For the design operating voltage of 300 V the centerline electron density was found to decrease from approximately 1.8 x 10 exp 17 cubic meters at a distance of 0.3 m to 1.8 X 10 exp 14 cubic meters at a distance of 4 m from the thruster. The electron temperature over the same region was between 1.7 and 3.5 eV. Ion current density measurements showed that the plume was sharply peaked, dropping by a factor of 2.6 within 22 degrees of centerline. The ion energy 4 m from the thruster and 15 degrees off-centerline was approximately 270 V. The thruster cathode flow rate and facility pressure were found to strongly affect the plume properties. In addition to the plume measurements, the data from the various probe types were used to assess the impact of probe design criteria

Myers, Roger M.; Manzella, David H.

1994-01-01

209

Plume base flow simulation technology  

NASA Technical Reports Server (NTRS)

A combined analytical/empirical approach was studied in an effort to define the plume simulation parameters for base flow. For design purposes, rocket exhaust simulation (i.e., plume simulation) is determined by wind tunnel testing. Cold gas testing was concluded to be a cost and schedule effective data base of substantial scope. The results fell short of the target, although work conducted was conclusive and advanced the state of the art. Comparisons of wind tunnel predictions with Space Transportation System (STS) flight data showed considerable differences. However, a review of the technology program data base has yielded an additional parameter that may correlate flight and cold gas test data. Data from the plume technology program and the NASA test flights are presented to substantiate the proposed simulation parameters.

Roberts, B. B.; Wallace, R. O.; Sims, J. L.

1983-01-01

210

Mobile Bay turbidity plume study  

NASA Technical Reports Server (NTRS)

Laboratory and field transmissometer studies on the effect of suspended particulate material upon the appearance of water are reported. Quantitative correlations were developed between remotely sensed image density, optical sea truth data, and actual sediment load. Evaluation of satellite image sea truth data for an offshore plume projects contours of transmissivity for two different tidal phases. Data clearly demonstrate the speed of change and movement of the optical plume for water patterns associated with the mouth of Mobile bay in which relatively clear Gulf of Mexico water enters the bay on the eastern side. Data show that wind stress in excess of 15 knots has a marked impact in producing suspended sediment loads.

Crozier, G. F.

1976-01-01

211

Simple models of tropical plumes  

E-print Network

. Tropical plumes and related phenomena. . . , . III MODEL AND METHOD IV SIMULATIONS AND DISCUSSION a. Overview 16 b. Simulation 0 ? zonally asymmetric initial state. . . . . c. Simulation 1 ? a tropical plume. . . d. Simulation 2 ? forcing 4' poleward... (dashed, interval 107 m2 s-1) at day 8. . 32 26 Simulation 2 divergence (interval 10-s s-1, dashed & 0) at day 8. . . . 32 27 Simulation 2 smoothed Rossby source (interval 10-~ s-1 day-1, dashed & 0) at day 8. . . . . 33 28 Simulation 2 height (solid...

Carrie, Gordon David, d 1960-

1994-01-01

212

Dynamics of laser ablated colliding plumes  

SciTech Connect

We report the dynamics of single and two collinearly colliding laser ablated plumes of ZnO studied using fast imaging and the spectroscopic measurements. Two dimensional imaging of expanding plume and temporal evolution of various species in interacting zones of plumes are used to calculate plume front velocity, electron temperature, and density of plasma. The two expanding plumes interact with each other at early stage of expansion ({approx}20 ns) resulting in an interaction zone that propagates further leading to the formation of stagnation layer at later times (>150 ns) at the lateral collision front of two plumes. Colliding plumes have larger concentration of higher ionic species, higher temperature, and increased electron density in the stagnation region. A one-to-one correlation between the imaging and optical emission spectroscopic observations in interaction zone of the colliding plumes is reported.

Gupta, Shyam L.; Pandey, Pramod K.; Thareja, Raj K. [Department of Physics, Indian Institute of Technology, Kanpur-208016 (India)

2013-01-15

213

Exhaust Nozzle Plume and Shock Wave Interaction  

NASA Technical Reports Server (NTRS)

Fundamental research for sonic boom reduction is needed to quantify the interaction of shock waves generated from the aircraft wing or tail surfaces with the exhaust plume. Both the nozzle exhaust plume shape and the tail shock shape may be affected by an interaction that may alter the vehicle sonic boom signature. The plume and shock interaction was studied using Computational Fluid Dynamics simulation on two types of convergent-divergent nozzles and a simple wedge shock generator. The nozzle plume effects on the lower wedge compression region are evaluated for two- and three-dimensional nozzle plumes. Results show that the compression from the wedge deflects the nozzle plume and shocks form on the deflected lower plume boundary. The sonic boom pressure signature of the wedge is modified by the presence of the plume, and the computational predictions show significant (8 to 15 percent) changes in shock amplitude.

Castner, Raymond S.; Elmiligui, Alaa; Cliff, Susan

2013-01-01

214

OZONE FORMATION IN POLLUTANT PLUMES: A REACTIVE PLUME MODEL WITH ARBITRARY CROSSWIND RESOLUTION  

EPA Science Inventory

A new two-layer reactive plume model is developed, in which arbitrary crosswind resolution of the emission field of each precursor is preserved, and dynamic plume-plume and plume-background interactions are explictly accomodated. The model has a hybrid formulation, having Lagrang...

215

Accurate and universal delineation of prokaryotic species.  

PubMed

The exponentially increasing number of sequenced genomes necessitates fast, accurate, universally applicable and automated approaches for the delineation of prokaryotic species. We developed specI (species identification tool; http://www.bork.embl.de/software/specI/), a method to group organisms into species clusters based on 40 universal, single-copy phylogenetic marker genes. Applied to 3,496 prokaryotic genomes, specI identified 1,753 species clusters. Of 314 discrepancies with a widely used taxonomic classification, >62% were resolved by literature support. PMID:23892899

Mende, Daniel R; Sunagawa, Shinichi; Zeller, Georg; Bork, Peer

2013-09-01

216

MATHEMATICAL MODEL FOR MULTIPLE COOLING TOWER PLUMES  

EPA Science Inventory

A mathematical model is developed for the prediction of plume properties such as excess plume temperature, humidity and liquid phase moisture (water droplet), plume trajectory, width, and dilution at the merging locations and the beginning and ending points of the visible part of...

217

Plasma plume MHD power generator and method  

DOEpatents

A method is described of generating power at a situs exposed to the solar wind which comprises creating at separate sources at the situs discrete plasma plumes extending in opposed directions, providing electrical communication between the plumes at their source and interposing a desired electrical load in the said electrical communication between the plumes.

Hammer, J.H.

1993-08-10

218

There Must Be Something in the Water: Investigating How Underground Pollutants Contaminate the Water Supply  

NSDL National Science Digital Library

In this lesson, students explore how groundwater contamination can spread through aquifers by participating in a groundwater plume simulation. They will learn how to determine the source of groundwater contamination, explore the possible contamination of Nevada groundwater by a major nuclear test site, and write a persuasive essay from the point of view of a Nevada resident living close to a groundwater contamination source.

219

Biogeochemical characterisation of a coal tar distillate plume.  

PubMed

The distillation of acidified coal tars for up to 50 years has given rise to a phenol plume approximately 500 m long, 50 m deep and containing up to 15 g l(-1) dissolved organic carbon (DOC) in the Triassic Sandstones aquifer. A conceptual biogeochemical model based on chemical and microbiological analysis of groundwater samples has been developed as a preliminary to more detailed studies of the controls on natural attenuation. While the development of redox zones and the production of methane and carbon dioxide provide evidence of natural attenuation, it appears that degradation is slow. The existence of sulphate in the plume indicates that this electron acceptor has not been depleted and that consequently methanogenesis is probably limited. Based on a simple estimate of sulphate input concentration, a half-life of about 15 years has been estimated for sulphate reduction. Geochemical modelling predicts that increased alkalinity within the plume has not led to carbonate precipitation, and thus within the limits of accuracy of the measurement, alkalinity may reflect the degree of biodegradation. This implies a loss of around 18% of the DOC over a 30-year period. Despite limited degradation, microbial studies show that there are diverse microbial communities in the aquifer with the potential for both anaerobic and aerobic biodegradation. Microbial activity was found to be greatest at the leading edge of the plume where DOC concentrations are 60 mg l(-1) or less, but activity could still be observed in more contaminated samples even though cells could not be cultured. The study suggests that degradation may be limited by the high phenol concentrations within the core of the plume, but that once diluted by dispersion, natural attenuation may proceed. More detailed studies to confirm these initial findings are identified and form the basis of associated papers. PMID:11820470

Williams, G M; Pickup, R W; Thornton, S F; Lerner, D N; Mallinson, H E; Moore, Y; White, C

2001-12-15

220

Motion of Pacific mantle plumes  

Microsoft Academic Search

The Hawaiian--Emperor hotspot chain, and its distinctive bend at 47 Ma, have figured prominently in the development of ideas on the nature of mantle plumes, plate motion, and frames of reference. However, paleomagnetic data from Ocean Drilling Program (ODP) Leg 197, together with results from plate circuit and geodynamic modeling studies, indicate southward motion of the Hawaiian hotspot during formation

R. D. Cottrell; J. A. Tarduno; P. V. Doubrovine

2007-01-01

221

Heat sources for mantle plumes  

NASA Astrophysics Data System (ADS)

Melting anomalies in the Earth's upper mantle have often been attributed to the presence of mantle plumes that may originate in the lower mantle, possibly from the core-mantle boundary. Globally, mantle plumes exhibit a large range in buoyancy flux that is proportional to their temperature and volume. Plumes with higher buoyancy fluxes should have higher temperatures and experience higher degrees of partial melting. This excess heat in mantle plumes could reflect either (1) an enrichment of the heat-producing elements (HPE: U, Th, K) in their mantle source leading to an increase of heat production by radioactive decay, (2) material transport from core to mantle (either advective or diffusive), or (3) conductive heat transport across the core-mantle boundary. The advective/diffusive transport of heat may result in a physical contribution of material from the core to the lower mantle. If core material is incorporated into the lower mantle, mantle plumes with a higher buoyancy flux should have higher core tracers, e.g., increased 186Os, 187Os, and Fe concentrations. Geophysical and dynamic modeling indicate that at least Afar, Easter, Hawaii, Louisville, and Samoa may all originate at the core-mantle boundary. These plumes encompass the whole range of known buoyancy fluxes from 0.9 Mg s-1 (Afar) to 8.7 Mg s-1 (Hawaii), providing evidence that the buoyancy flux is largely independent of other geophysical parameters. In an effort to explore whether the heat-producing elements are the cause of excess heat we looked for correlations between fractionation-corrected concentrations of the HPE and buoyancy flux. Our results suggest that there is no correlation between HPE concentrations and buoyancy flux (with and without an additional correction for variable degrees of partial melting). As anticipated, K, Th, and U are positively correlated with each other (e.g., Hawaii, Iceland, and Galapagos have significantly lower concentrations than, e.g., Tristan da Cunha, the Canary Islands, and the Azores). We also find no correlation between Fe and buoyancy flux. The apparent lack of correlations suggests that excess heat may be a result of conductive heat contribution from the core or from the adjacent boundary layer. Thus, the formation of mantle plumes along the core-mantle boundary may be largely controlled by distance of enriched material from the core-mantle boundary.

Beier, C.; Rushmer, T.; Turner, S. P.

2008-06-01

222

Applying Contamination Modelling to Spacecraft Propulsion Systems Designs and Operations  

NASA Technical Reports Server (NTRS)

Molecular and particulate contaminants generated from the operations of a propulsion system may impinge on spacecraft critical surfaces. Plume depositions or clouds may hinder the spacecraft and instruments from performing normal operations. Firing thrusters will generate both molecular and particulate contaminants. How to minimize the contamination impact from the plume becomes very critical for a successful mission. The resulting effect from either molecular or particulate contamination of the thruster firing is very distinct. This paper will discuss the interconnection between the functions of spacecraft contamination modeling and propulsion system implementation. The paper will address an innovative contamination engineering approach implemented from the spacecraft concept design, manufacturing, integration and test (I&T), launch, to on- orbit operations. This paper will also summarize the implementation on several successful missions. Despite other contamination sources, only molecular contamination will be considered here.

Chen, Philip T.; Thomson, Shaun; Woronowicz, Michael S.

2000-01-01

223

Liquid Booster Module (LBM) plume flowfield model  

NASA Technical Reports Server (NTRS)

A complete definition of the LBM plume is important for many Shuttle design criteria. The exhaust plume shape has a significant effect on the vehicle base pressure. The LBM definition is also important to the Shuttle base heating, aerodynamics and the influence of the exhaust plume on the launch stand and environment. For these reasons a knowledge of the LBM plume characteristics is necessary. A definition of the sea level LBM plume as well as at several points along the Shuttle trajectory to LBM, burnout is presented.

Smith, S. D.

1981-01-01

224

Physical observations in the plume region of the Amazon River during peak discharge---I. Surface variability  

Microsoft Academic Search

Satellite imagery in the 0.4-1.1 mum band from GOES, NOAA-7 and NIMBUS-7 and shipboard measurements of suspended sediment concentration and chlorophyll are synthesized. Five main surface features are delineated in the plume region of the Amazon during peak discharge: a River Zone (RZ), Interaction Zones A, B and C (IZA, IZB, IZC), and a Nearshore Zone (NZ). The loci, temporal

Thomas B. Curtin; Richard V. Legeckis

1986-01-01

225

Deployment Plan for Bioremediation and Natural Attenuation for In Situ Restoration of Chloroethene-Contaminated Groundwater  

SciTech Connect

This deployment plan describes a project funded by the Accelerated Site Technology Deployment Program of the U.S. Department of Energy (DOE). The objective is to facilitate deployment of enhanced in situ bioremediation (ISB) an monitored natural attenuation (MNA) or chloroethene-contaminated groundwater to DOE sites. Enhanced ISB accelerates dechlorination of chloroethenes under anaerobic conditions by providing nutrients to the microbial community. Natural attenuation does not require nutrient addition. Enhanced ISB in the upgradient portion of a contaminant plume couples with MNA in the downgradient portion is being implemented at Test Area North (TAN) at the Idaho National Engineering and Environmental Laboratory. Selected DOE sites will be screened to assess their suitability for enhanced ISB/MNA. Tasks include: (1) characterization of the TAN microbial community and correlation of community characteristics with chloroethene degradation ability, (2) installation of wells to facilitate evaluation of MNA at TAN, (3) monitoring to better delineate MNA at TAN, and (4) screening of selected other DOE sites for suitability of ISB/MNA, and limited supplemental characterization. Data evaluation will provide a sound technical basis for decision makers to consider use of enhanced ISB and MNA, alone or together, as remedial technologies for these sites.

Peterson, L.N.; Starr, R.C.; Sorenson, K.S.; Smith, R.W.; Phelps, T.J.

1999-03-01

226

Plasma plume MHD power generator and method  

DOEpatents

Highly-conducting plasma plumes are ejected across the interplanetary magnetic field from a situs that is moving relative to the solar wind, such as a spacecraft or an astral body, such as the moon, having no magnetosphere that excludes the solar wind. Discrete plasma plumes are generated by plasma guns at the situs extending in opposite directions to one another and at an angle, preferably orthogonal, to the magnetic field direction of the solar wind plasma. The opposed plumes are separately electrically connected to their source by a low impedance connection. The relative movement between the plasma plumes and the solar wind plasma creates a voltage drop across the plumes which is tapped by placing the desired electrical load between the electrical connections of the plumes to their sources. A portion of the energy produced may be used in generating the plasma plumes for sustained operation.

Hammer, James H. (Livermore, CA)

1993-01-01

227

Instability of waste plumes adsorbed on iron oxide in soils  

SciTech Connect

Iron (hydrous) oxide coatings on the solid matrix dominate adsorption in many soils. Their adsorption characteristics vary considerably with the composition of the soil pore water. If the latter is not sufficiently buffered, the contaminant distribution between solid and soluble soil phase, Kd (''distribution coefficient''), will change as intruding water differing in chemical composition from the original one in the system progresses through the plume environment. Thus the Kd's at different locations within the plume become time dependent, spatially variable and causally correlated. The conventional constant or stochastic Kd model is not capable of describing contaminant migration in such a situation. A geochemical equilibrium model, the so-called triple layer model, has been incorporated into a transport code and is used to calculate the adsorption processes and thus the Kd as a function of environmental parameters. The major processes occurring are: (1) accumulation of a proton reservoir on the surface itself; (2) development of a charge cloud at a distance of several angstroms from the surface, capable of accommodating contaminant ions; and (3) development of a net charge at the oxide/water interface and, consequently, the creation of a cation or anion exchange capacity of the oxide.

Gruber, J.

1987-03-01

228

Infrared recordings for characterizing an aircraft plume  

NASA Astrophysics Data System (ADS)

Some key electro-optical measurements required to characterize an aircraft plume for automated recognition are shown, as well as some aspects of the processing and use of these measurements. Plume measurements with Short Wavelength Infrared (1.1 - 2.5 um), Mid-Wavelength Infrared (2.5 - 7 um) and Long Wavelength Infrared (7 - 15 um) cameras are presented, as well as spectroradiometer measurements covering the whole Mid-Wavelength, Long Wavelength and upper part of the Short Wavelength Infrared bands. The two limiting factors for the detection of the plume, i.e. the atmospheric transmission bands and the plume emission bands, are discussed, and it is shown how a micro turbine engine can assist in aircraft plume studies. One such a study, regarding the differentiation between an aircraft plume and a blackbody emitter using subbands in the Mid-Wavelength Infrared, is presented. The factors influencing aircraft plume emission are discussed, and the measurements required to characterize an aircraft plume for the purpose of constructing a mathematical plume model are indicated. Since the required measurements are prescribed by the plume model requirements, a brief overview of the plume model, that can be used to simulate the results of the plume's emission under different conditions and observation configurations, is given. Such a model can be used to test the robustness of algorithms, like the mentioned subband method, for identifying aircraft plumes. Such a model furthermore enables the simulation of measurements that would be obtained by an electro-optical system, like an infrared seekerhead of a missile, of a plume for the purpose of algorithm training under various simulated environmental conditions.

Retief, S. J. P.; Dreyer, M. M.; Brink, C.

2014-06-01

229

Compositional differentiation of Enceladus' plume  

NASA Astrophysics Data System (ADS)

The Cosmic Dust Analyser (CDA) on board the Cassini spacecraft sampled Enceladus' plume ice particles emanated directly from Enceladus' fractured south polar terrain (SPT), the so-called "Tiger Stripes", during two consecutive flybys (E17 and E18) in 2012. The spacecraft passed through the dense plume with a moderate velocity of ~7.5km/s, horizontally to the SPT with a closest approach (CA) at an altitude of ~75km almost directly over the south pole. In both flybys, spectra were recorded during a time interval of ~ ±3 minutes with respect to the closest approach achieving an average sampling rate of about 0.6 sec-1. We assume that the spacecraft passed through the plume during an interval of about ±60(sec) from the CA. Particles encountered before and after this period are predominately from the E-ring background in which Enceladus is embedded. Most CDA TOF-mass spectra are identified as one of three compositional types: (i) almost pure water (ii) organic rich and (iii) salt rich [2]. A Boxcar Analysis (BCA) is performed from a count database for compositional mapping of the plume along the space-craft trajectory. In BCA, counts of each spectrum type are integrated for a certain interval of time (box size). The integral of counts represents frequencies of compositional types in absolute abundances, which are converted later into proportions. This technique has been proven to be a suitable for inferring the compositional profiles from an earlier flyby (E5) [1]. The inferred compositional profiles show similar trends on E17 and E18. The abundances of different compositional types in the plume clearly differ from the Ering background and imply a compositional differentiation inside the plume. Following up the work of Schmidt et al, 2008 and Postberg et al, 2011 we can link different compositional types to different origins. The E17/E18 results are compared with the E5 flyby in 2008, which yielded the currently best compositional profile [2] but was executed at much higher velocity (~17.6km/s) and a very different, highly inclined, flyby geometry.

Khawaja, N.; Postberg, F.; Schmidt, J.

2014-04-01

230

Teaching the Mantle Plumes Debate  

NASA Astrophysics Data System (ADS)

There is an ongoing debate regarding whether or not mantle plumes exist. This debate has highlighted a number of issues regarding how Earth science is currently practised, and how this feeds into approaches toward teaching students. The plume model is an hypothesis, not a proven fact. And yet many researchers assume a priori that plumes exist. This assumption feeds into teaching. That the plume model is unproven, and that many practising researchers are skeptical, may be at best only mentioned in passing to students, with most teachers assuming that plumes are proven to exist. There is typically little emphasis, in particular in undergraduate teaching, that the origin of melting anomalies is currently uncertain and that scientists do not know all the answers. Little encouragement is given to students to become involved in the debate and to consider the pros and cons for themselves. Typically teachers take the approach that “an answer” (or even “the answer”) must be taught to students. Such a pedagogic approach misses an excellent opportunity to allow students to participate in an important ongoing debate in Earth sciences. It also misses the opportunity to illustrate to students several critical aspects regarding correct application of the scientific method. The scientific method involves attempting to disprove hypotheses, not to prove them. A priori assumptions should be kept uppermost in mind and reconsidered at all stages. Multiple working hypotheses should be entertained. The predictions of a hypothesis should be tested, and unpredicted observations taken as weakening the original hypothesis. Hypotheses should not be endlessly adapted to fit unexpected observations. The difficulty with pedagogic treatment of the mantle plumes debate highlights a general uncertainty about how to teach issues in Earth science that are not yet resolved with certainty. It also represents a missed opportunity to let students experience how scientific theories evolve, warts and all. Working with students to enable them to participate in the evolution of the subject and to share in the excitement of major developments is surely the best way to attract them to science.

Foulger, G. R.

2010-12-01

231

Delta Chromium-53/52 isotopic composition of native and contaminated groundwater, Mojave Desert, USA  

USGS Publications Warehouse

Chromium(VI) concentrations in groundwater sampled from three contaminant plumes in aquifers in the Mojave Desert near Hinkley, Topock and El Mirage, California, USA, were as high as 2600, 5800 and 330 ?g/L, respectively. ?53/52Cr compositions from more than 50 samples collected within these plumes ranged from near 0‰ to almost 4‰ near the plume margins. Assuming only reductive fractionation of Cr(VI) to Cr(III) within the plume, apparent fractionation factors for ?53/52Cr isotopes ranged from ?app = 0.3 to 0.4 within the Hinkley and Topock plumes, respectively, and only the El Mirage plume had a fractionation factor similar to the laboratory derived value of ? = 3.5. One possible explanation for the difference between field and laboratory fractionation factors at the Hinkley and Topock sites is localized reductive fractionation of Cr(VI) to Cr(III), with subsequent advective mixing of native and contaminated water near the plume margin. Chromium(VI) concentrations and ?53/52Cr isotopic compositions did not uniquely define the source of Cr near the plume margin, or the extent of reductive fractionation within the plume. However, Cr(VI) and ?53/52Cr data contribute to understanding of the interaction between reductive and mixing processes that occur within and near the margins of Cr contamination plumes. Reductive fractionation of Cr(VI) predominates in plumes having higher ?app, these plumes may be suitable for monitored natural attenuation. In contrast, advective mixing predominates in plumes having lower ?app, the highly dispersed margins of these plumes may be difficult to define and manage.

Izbicki, John A.; Bullen, Thomas D.; Martin, Peter; Schroth, Brian

2012-01-01

232

Harnessing genomics for delineating conservation units  

PubMed Central

Genomic data have the potential to revolutionize the delineation of conservation units (CUs) by allowing the detection of adaptive genetic variation, which is otherwise difficult for rare, endangered species. In contrast to previous recommendations, we propose that the use of neutral versus adaptive markers should not be viewed as alternatives. Rather, neutral and adaptive markers provide different types of information that should be combined to make optimal management decisions. Genetic patterns at neutral markers reflect the interaction of gene flow and genetic drift that affects genome-wide variation within and among populations. This population genetic structure is what natural selection operates on to cause adaptive divergence. Here, we provide a new framework to integrate data on neutral and adaptive markers to protect biodiversity. PMID:22727017

Funk, W. Chris; McKay, John K.; Hohenlohe, Paul A.; Allendorf, Fred W.

2014-01-01

233

Characterization and monitoring of contaminated sites by multi-geophysical approach (IP, ERT and GPR).  

NASA Astrophysics Data System (ADS)

The contamination of soils and groundwater by hydrocarbons, due to blow out, leakage from tank or pipe and oil spill, is a heavy environmental problem because infiltrated oil can persist in the ground for a long time leading to important changes on soils and physical and biogeochemical properties, which impact on ecosystems and shallow aquifers. The existing methods used for the characterization of hydrocarbon contaminated sites are invasive, time consuming and expensive. Therefore, in the last years, there was a growing interest in the use of geophysical methods for environmental monitoring (Börner et al., 1993; Vanhala, 1997; Atekwana et al., 2000; Chambers et al., 2004; Song et al., 2005; French et al., 2009). The goal of this work is to characterize underground contaminant distributions and monitoring a remediation activity using a multi-geophysical approach (cross-hole IP and ERT, GPR). The experiments consist in geophysical measurements both in surface and boreholes, to monitor a simulated hydrocarbon leachate into a ~1 m3 box. The tank is filled with quartz-rich sand (k = 1.16 x 10-12 m2) and it is equipped with six boreholes and 72 stainless steel ring electrodes, at 5 cm spacing, for cross-hole electrical resistivity and time-domain IP measurements. 25 additional stainless steel electrodes were installed at the surface of the tank. Two measurement phases were realized: first, we monitored electrical resistivity, IP, and dielectric conductivity of the uncontaminated soil; the second experimental phase consists in the geophysical monitoring of a crude oil controlled spill. Results showed significant changes in the responses of geoelectrical measurements in presence of a crude oil contamination. Instead IP results give a phase angle distribution related to the presence of hydrocarbon in the system but not so clear in the location of plume. Therefore, to clearly delineate the areas interested by contamination, we estimate the imaginary component of electrical resistivity. Finally, the electrical behaviour of the medium from GPR data, compared to geoelectrical measurements, was investigated by the analysis of the strength of EM-reflections and absorption of EM signal. In particular, the most contaminated areas are characterized by a variation of soil permittivity dielectric value. Furthermore, the frequency analysis show a significant downshift of the frequency in correspondence of contaminated areas. In conclusion, the experiment was able to obtain information about contaminant distribution in the subsurface. Besides combining measurements from multiple geophysical measurements allow us to obtain more accurate characterization of contamination spatial variability. Finally, the estimation of geophysical parameters in frequency domain gave a supplementary information to increase quality of acquired data.

Giampaolo, Valeria; Capozzoli, Luigi; Votta, Mario; Rizzo, Enzo

2014-05-01

234

Costs of groundwater contamination  

SciTech Connect

Two factors determine the cost of groundwater contamination: (1) the ways in which water was being used or was expected to be used in the future and (2) the physical characteristics of the setting that constrain the responses available to regain lost uses or to prevent related damages to human health and the environment. Most contamination incidents can be managed at a low enough cost that uses will not be foreclosed. It is important to take into account the following when considering costs: (1) natural cleansing through recharge and dilution can take many years; (2) it is difficult and costly to identify the exact area and expected path of a contamination plume; and (3) treatment or replacement of contaminated water often may represent the cost-effective strategy for managing the event. The costs of contamination include adverse health effects, containment and remediation, treatment and replacement costs. In comparing the costs and benefits of prevention programs with those of remediation, replacement or treatment, it is essential to adjust the cost/benefit numbers by the probability of their actual occurrence. Better forecasts of water demand are needed to predict more accurately the scarcity of new supply and the associated cost of replacement. This research should include estimates of the price elasticity of water demand and the possible effect on demand of more rational cost-based pricing structures. Research and development of techniques for in situ remediation should be encouraged.

O'Neil, W.B.; Raucher, R.S. (Environmental Protection Agency, Washington, DC (United States))

1990-01-01

235

Innovative Strategy For Long Term Monitoring Of Metal And Radionuclide Plumes  

SciTech Connect

Many government and private industry sites that were once contaminated with radioactive and chemical wastes cannot be cleaned up enough to permit unrestricted human access. The sites will require long term management, in some cases indefinitely, leaving site owners with the challenge of protecting human health and environmental quality at these "legacy" sites. Long-term monitoring of groundwater contamination is one of the largest projected costs in the life cycle of environmental management at the Savannah River Site, the larger DOE complex, and many large federal and private sites. There is a need to optimize the performance and manage the cost of long term surveillance and monitoring at their sites. Currently, SRNL is initiating a pilot field test using alternative protocols for long term monitoring of metals and radionuclides. A key component of the approach is that monitoring efforts are focused on measurement of low cost metrics related to hydrologic and chemical conditions that control contaminant migration. The strategy combines careful monitoring of hydrologic boundary conditions with measurement of master variables such as chemical surrogates along with a smaller number of standard well analyses. In plumes contaminated with metals, master variables control the chemistry of the groundwater system, and include redox variables (ORP, DO, chemicals), pH, specific conductivity, biological community (breakdown/decay products), and temperature. Significant changes in these variables will result in conditions whereby the plume may not be stable and therefore can be used to predict possible plume migration. Conversely, concentration measurements for all types of contaminants in groundwater are a lagging indicator plume movement - major changes contaminant concentrations indicate that contamination has migrated. An approach based on measurement of master variables and explicit monitoring of hydrologic boundary conditions combined with traditional metrics should lead to improved monitoring while simultaneously reducing costs. This paradigm is being tested at the SRS F-Area where an innovative passive remedial system is being monitored and evaluated over the long term prior to traditional regulatory closure. Contaminants being addressed at this site are uranium, strontium-90, iodine-129, and tritium. We believe that the proposed strategies will be more effective in early identification of potential risks; these strategies will also be cost effective because controlling variables are relatively simple to measure. These variables also directly reflect the evolution of the plume through time, so that the monitoring strategy can be modified as the plume 'ages'. This transformational long-term monitoring paradigm will generate large cost savings to DOE, other federal agencies and industry and will provide improved performance and leading indicators of environmental management performance.

Eddy-Dilek, Carol; Millings, Margaret R.; Looney, Brian B.; Denham, Miles E.

2014-01-08

236

Enhanced biodegradation by hydraulic heterogeneities in petroleum hydrocarbon plumes.  

PubMed

In case of dissolved electron donors and acceptors, natural attenuation of organic contaminant plumes in aquifers is governed by hydrodynamic mixing and microbial activity. Main objectives of this work were (i) to determine whether aerobic and anaerobic biodegradation in porous sediments is controlled by transverse dispersion, (ii) to elucidate the effect of sediment heterogeneity on mixing and biodegradation, and (iii) to search for degradation-limiting factors. Comparative experiments were conducted in two-dimensional sediment microcosms. Aerobic toluene and later ethylbenzene degradation by Pseudomonas putida strain F1 was initially followed in a plume developing from oxic to anoxic conditions and later under steady-state mixing-controlled conditions. Competitive anaerobic degradation was then initiated by introduction of the denitrifying strain Aromatoleum aromaticum EbN1. In homogeneous sand, aerobic toluene degradation was clearly controlled by dispersive mixing. Similarly, under denitrifying conditions, microbial activity was located at the plume's fringes. Sediment heterogeneity caused flow focusing and improved the mixing of reactants. Independent from the electron accepting process, net biodegradation was always higher in the heterogeneous setting with a calculated efficiency plus of 23-100% as compared to the homogeneous setup. Flow and reactive transport model simulations were performed in order to interpret and evaluate the experimental results. PMID:19095328

Bauer, Robert D; Rolle, Massimo; Bauer, Sebastian; Eberhardt, Christina; Grathwohl, Peter; Kolditz, Olaf; Meckenstock, Rainer U; Griebler, Christian

2009-02-27

237

Enhanced biodegradation by hydraulic heterogeneities in petroleum hydrocarbon plumes  

NASA Astrophysics Data System (ADS)

In case of dissolved electron donors and acceptors, natural attenuation of organic contaminant plumes in aquifers is governed by hydrodynamic mixing and microbial activity. Main objectives of this work were (i) to determine whether aerobic and anaerobic biodegradation in porous sediments is controlled by transverse dispersion, (ii) to elucidate the effect of sediment heterogeneity on mixing and biodegradation, and (iii) to search for degradation-limiting factors. Comparative experiments were conducted in two-dimensional sediment microcosms. Aerobic toluene and later ethylbenzene degradation by Pseudomonas putida strain F1 was initially followed in a plume developing from oxic to anoxic conditions and later under steady-state mixing-controlled conditions. Competitive anaerobic degradation was then initiated by introduction of the denitrifying strain Aromatoleum aromaticum EbN1. In homogeneous sand, aerobic toluene degradation was clearly controlled by dispersive mixing. Similarly, under denitrifying conditions, microbial activity was located at the plume's fringes. Sediment heterogeneity caused flow focusing and improved the mixing of reactants. Independent from the electron accepting process, net biodegradation was always higher in the heterogeneous setting with a calculated efficiency plus of 23-100% as compared to the homogeneous setup. Flow and reactive transport model simulations were performed in order to interpret and evaluate the experimental results.

Bauer, Robert D.; Rolle, Massimo; Bauer, Sebastian; Eberhardt, Christina; Grathwohl, Peter; Kolditz, Olaf; Meckenstock, Rainer U.; Griebler, Christian

2009-02-01

238

Mantle plumes on Venus revisited  

NASA Astrophysics Data System (ADS)

The Equatorial Highlands of Venus consist of a series of quasicircular regions of high topography, rising up to about 5 km above the mean planetary radius. These highlands are strongly correlated with positive geoid anomalies, with a peak amplitude of 120 m at Atla Regio. Shield volcanism is observed at Beta, Eistla, Bell, and Atla Regiones and in the Hathor Mons-Innini Mons-Ushas Mons region of the southern hemisphere. Volcanos have also been mapped in Phoebe Regio and flood volcanism is observed in Ovda and Thetis Regiones. Extensional tectonism is also observed in Ovda and Thetis Regiones. Extensional tectonism is also observed in many of these regions. It is now widely accepted that at least Beta, Atla, Eistla, and Bell Regiones are the surface expressions of hot, rising mantel plumes. Upwelling plumes are consistent with both the volcanism and the extensional tectonism observed in these regions. The geoid anomalies and topography of these four regions show considerable variation. Peak geoid anomalies exceed 90 m at Beta and Atla, but are only 40 m at Eistla and 24 m at Bell. Similarly, the peak topography is greater at Beta and Atla than at Eistla and Bell. Such a range of values is not surprising because terrestrial hotspot swells also have a side range of geoid anomalies and topographic uplifts. Kiefer and Hager used cylindrical axisymmetric, steady-state convection calculations to show that mantle plumes can quantitatively account for both the amplitude and the shape of the long-wavelength geoid and topography at Beta and Atla. In these models, most of the topography of these highlands is due to uplift by the vertical normal stress associated with the rising plume. Additional topography may also be present due to crustal thickening by volcanism and crustal thinning by rifting. Smrekar and Phillips have also considered the geoid and topography of plumes on Venus, but they restricted themselves to considering only the geoid-topography ratio and did not examine either the geoid and topography amplitudes separately or the shapes of anomalies.

Kiefer, Walter S.

1992-12-01

239

Delineation of the Postprostatectomy Prostate Bed Using Computed Tomography: Interobserver Variability Following the EORTC Delineation Guidelines  

SciTech Connect

Purpose: The present study aims to assess the interobserver agreement of prostate bed delineation after radical prostatectomy using CT alone as proposed by the European Organization for Research and Treatment of Cancer (EORTC) guidelines. Methods and Materials: Six observers delineated the postoperative prostate bed (PB) and the original seminal vesicle position or remnants (SV) of 10 patients according to the EORTC guidelines. Contours were then compared for agreement between observers (the apparent volume overlap and generalized kappa statistics). Standard deviations were also calculated to measure the variability of the position of the outer margins. Results: The mean volume of 100% agreement ({+-}1 standard deviation, SD) was only 5.0 ({+-}3.3) ml for the PB and 0.9 ({+-}1.5) ml for the SV, whereas the mean union of all contours ({+-}1 SD) was 41.1 ({+-}11.8) ml and 25.3 ({+-}13.4) ml, respectively. The mean overall agreement corrected for chance was moderate for both the PB (mean kappa, 0.49; range, 0.35-0.62) and SV (mean kappa, 0.42; range, 0.22-0.59). The overall SD of the outer margins of the PB ranged from 4.6 to 7.0 mm Conclusion: The delineation of the postprostatectomy bed using CT shows only a moderate observer agreement when following the EORTC guidelines.

Ost, Piet, E-mail: piet.ost@ugent.be [Department of Radiotherapy, Ghent University Hospital, Ghent (Belgium); De Meerleer, Gert; Vercauteren, Tom; De Gersem, Werner; Veldeman, Liv; Vandecasteele, Katrien; Fonteyne, Valerie [Department of Radiotherapy, Ghent University Hospital, Ghent (Belgium); Villeirs, Geert [Department of Radiology, Ghent University Hospital, Ghent (Belgium)

2011-11-01

240

Potential perchlorate exposure from Citrus sp. irrigated with contaminated water  

Microsoft Academic Search

Citrus produced in the southwestern United States is often irrigated with perchlorate-contaminated water. This irrigation water includes Colorado River water which is contaminated with perchlorate from a manufacturing plant previously located near the Las Vegas Wash, and ground water from wells in Riverside and San Bernardino counties of California which are affected by a perchlorate plume associated with an aerospace

C. A. Sanchez; R. I. Krieger; N. R. Khandaker; L. Valentin-Blasini; B. C. Blount

2006-01-01

241

Evaluation of methodology for delineation of protection zones around public-supply wells in west-central Florida  

USGS Publications Warehouse

Public-supply wells in the west-central Florida area of Citrus, Hernando, Pasco, Hillsborough, and Pinellas Counties derive their supply solely from the Floridan aquifer system. In much of this area, the Floridan is at or near land surface and vulnerable to contamination. Recognizing this potential threat to the aquifer, the Florida Department of Environmental Regulation (FDER) recently promulgated regulations providing for the delineation of protection zones around public-supply wells that tap vulnerable aquifers, such as the Floridan in west-central Florida. This report evaluates the methodology for delineation of protection zones for public supply wells in west-central Florida in accordance with the methods detailed in the FDER regulations. Protection zones were delineated for public supply wells or well fields that are permitted an average daily withdrawal of 100,000 gal or more from the Floridan aquifer system where it is unconfined or leaky confined. Leaky confined, as used in FDER regulations describe conditions such that the time for a particle of water to travel vertically from the water table to the top of the Floridan is 5 years or less. Protection zones were delineated by using a radial volumetric-displacement model that simulated 5 years of permitted-rate withdrawal. Where zones overlapped, such as for well fields, composite protection zones in shapes that varied according to the configuration of well arrays were delineated on maps. (USGS)

Vecchioli, John; Hunn, J.D.; Aucott, W.R.

1989-01-01

242

Space shuttle main engine plume radiation model  

NASA Technical Reports Server (NTRS)

The methods are described which are used in predicting the thermal radiation received by space shuttles, from the plumes of the main engines. Radiation to representative surface locations were predicted using the NASA gaseous plume radiation GASRAD program. The plume model is used with the radiative view factor (RAVFAC) program to predict sea level radiation at specified body points. The GASRAD program is described along with the predictions. The RAVFAC model is also discussed.

Reardon, J. E.; Lee, Y. C.

1978-01-01

243

Progression of natural attenuation processes at a crude-oil spill site . I. Geochemical evolution of the plume  

USGS Publications Warehouse

A 16-year study of a hydrocarbon plume shows that the extent of contaminant migration and compound-specific behavior have changed as redox reactions, most notably iron reduction, have progressed over time. Concentration changes at a small scale, determined from analysis of pore-water samples drained from aquifer cores, are compared with concentration changes at the plume scale, determined from analysis of water samples from an observation well network. The small-scale data show clearly that the hydrocarbon plume is growing slowly as sediment iron oxides are depleted. Contaminants, such as ortho-xylene that appeared not to be moving downgradient from the oil on the basis of observation well data, are migrating in thin layers as the aquifer evolves to methanogenic conditions. However, the plume-scale observation well data show that the downgradient extent of the Fe2+ and BTEX plume did not change between 1992 and 1995. Instead, depletion of the unstable Fe (III) oxides near the subsurface crude-oil source has caused the maximum dissolved iron concentration zone within the plume to spread at a rate of approximately 3 m/year. The zone of maximum concentrations of benzene, toluene, ethylbenzene and xylene (BTEX) has also spread within the anoxic plume. In monitoring the remediation of hydrocarbon-contaminated ground water by natural attenuation, subtle concentration changes in observation well data from the anoxic zone may be diagnostic of depletion of the intrinsic electron-accepting capacity of the aquifer. Recognition of these subtle patterns may allow early prediction of growth of the hydrocarbon plume. Copyright ?? 2001 .

Cozzarelli, I.M.; Bekins, B.A.; Baedecker, M.J.; Aiken, G.R.; Eganhouse, R.P.; Tuccillo, M.E.

2001-01-01

244

Modelling the fate of the Tijuana River discharge plume  

NASA Astrophysics Data System (ADS)

After rainfall events, the Tijuana River discharges excess runoff into the ocean in a highly turbid plume. The runoff waters contain large suspended solids concentrations, as well as high levels of toxic contaminants, bacteria, and hepatitis and enteroviruses. Public health hazards posed by the effluent often result in beach closures for several kilometers northward along the U.S. shoreline. A Delft3D model has been set up to predict the fate of the Tijuana River plume. The model takes into account the effects of tides, wind, waves, salinity, and temperature stratification. Heat exchange with the atmosphere is also included. The model consists of a relatively coarse outer domain and a high-resolution surf zone domain that are coupled with Domain Decomposition. The offshore boundary conditions are obtained from the larger NCOM SoCal model (operated by the US Navy) that spans the entire Southern California Bight. A number of discharge events are investigated, in which model results are validated against a wide range of field measurements in the San Diego Bight. These include HF Radar surface currents, REMUS tracks, drifter deployments, satellite imagery, as well as current and temperature profile measurements at a number of locations. The model is able to reproduce the observed current and temperature patterns reasonably well. Under calm conditions, the model results suggest that the hydrodynamics in the San Diego Bight are largely governed by internal waves. During rainfall events, which are typically accompanied by strong winds and high waves, wind and wave driven currents become dominant. An analysis will be made of what conditions determine the trapping and mixing of the plume inside the surfzone and/or the propagation of the plume through the breakers and onto the coastal shelf. The model is now also running in operational mode. Three day forecasts are made every 24 hours. This study was funded by the Office of Naval Research.

van Ormondt, M.; Terrill, E.; Hibler, L. F.; van Dongeren, A. R.

2010-12-01

245

FLOOD-PLAIN DELINEATION IN ICE JAM PRONE REGIONS  

E-print Network

FLOOD-PLAIN DELINEATION IN ICE JAM PRONE REGIONS By Richard M. Vogel,1 S. M. ASCE and Jery R. Stedinger,2 A. M. ASCE ABSTRACT:Flood-plain delineation in ice jam prone regions is in its infancy .A-plain boundaries. These results document the need to consider the probability of ice jam flood events

Vogel, Richard M.

246

Space simulation experiments on reaction control system thruster plumes  

NASA Technical Reports Server (NTRS)

A space simulation procedure was developed for studying rocket plume contamination effects using a 5-pound bipropellant reaction control system thruster. Vacuum chamber pressures of 3 x 10 to the minus 5 torr (70 miles altitude) were achieved with the thruster firing in pulse trains consisting of eight pulses (50 msec on, 100 msec off, and seven minutes between pulse trains). The final vacuum was achieved by cooling all vacuum chamber surfaces to liquid helium temperature and by introducing a continuous argon leak of 48 std. cc/sec into the test chamber. An effort was made to simulate propellant system flow dynamics corresponding to actual spacecraft mission use. Fast time response liquid flow rate measurements showed that large variations occurred in the ratio of oxidizer to fuel flow for pulse-on times up to 120 msec. These variations could lead to poor combustion efficiency and the production of contamination.

Cassidy, J. F.

1972-01-01

247

Space simulation experiments on reaction control system thruster plumes.  

NASA Technical Reports Server (NTRS)

A space simulation procedure was developed for studying rocket plume contamination effects using a 5-lb bipropellant reaction control system thrustor. Vacuum chamber pressures of 0.00003 torr (70 miles altitude) were achieved with the thrustor firing in pulse trains consisting of eight pulses - 50 msec on, 100 msec off, and seven minutes between pulse trains. The final vacuum was achieved by cooling all vacuum chamber surfaces to liquid-helium temperature and by introducing a continuous argon leak of 48 std. cc/sec into the test chamber. Fast time response liquid flow rate measurements showed that large variations occurred in the ratio of oxidizer to fuel flow for pulse-on times up to 120 msec. These variations could lead to poor combustion efficiency and the production of contamination.

Cassidy, J. F.

1972-01-01

248

Two-dimensional nozzle plume characteristics  

NASA Technical Reports Server (NTRS)

Future high performance aircraft will likely feature asymmetric or two-dimensional nozzles with or without ejectors. In order to design two-dimensional nozzle/ejector systems of minimum size and weight, the plume decay and spreading characteristics of basic two-dimensional nozzles must first be established. The present work deals with the experimental analyses of these plume characteristics and includes the effects of nozzle aspect ratio and flow conditions (jet Mach number and temperature) on the plume decay and spreading of two-dimensional nozzles. Correlations including these variables are developed in a manner similar to those previously developed successfully for conic and dual-flow plumes.

Von Glahn, Uwe H.

1987-01-01

249

Biogeochemistry of landfill leachate plumes  

Microsoft Academic Search

The literature has been critically reviewed in order to assess the attenuation processes governing contaminants in leachate affected aquifers. Attenuation here refers to dilution, sorption, ion exchange, precipitation, redox reactions and degradation processes. With respect to contaminants, focus is on dissolved organic matter, xenobiotic organic compounds, inorganic macrocomponents as anions and cations, and heavy metals. Laboratory as well as field

Thomas H Christensen; Peter Kjeldsen; Poul L Bjerg; Dorthe L Jensen; Jette B Christensen; Anders Baun; Hans-Jørgen Albrechtsen; Gorm Heron

2001-01-01

250

A pilot study for delineation of areas contributing water to wellfields at Jackson, Tennessee  

USGS Publications Warehouse

The U.S. Geological Survey, in cooperation with the Tennessee Department of Health and Environment, Division of Groundwater Protection, and the Jackson Utility Division, conducted a pilot study to determine data needs and the applicability of four methods for the delineation of wellhead protection areas. Jackson Utility Division in Jackson, Madison County, Tennessee, pumps about 9 million gallons of ground water daily from two municipal wellfields that tap an unconfined sand aquifer. Under natural hydraulic gradients, ground waterflows southward toward the South Wellfield at approximately 2 to 3 feet per day; natural flow toward the North Wellfield from the east at 1 to 2 feet per day. Water quality generally is suitable for most uses. Concentrations of dissolved solids are low, and excessive iron is the only significant naturally occurring water-quality problem. However, trace concentrations of volatile organic compounds have been detected in water pumps from the South Wellfield; the highest concentration of a single compound has been 23 micrograms per liter of tetrachloroethylene. Potential sources of ground-water contamination in the Jackson area include a hazardous-waste site, municipal and industrial landfill, and underground-storage tanks. Some of the four method for delineating wellhead protection areas did not adequately describe zones contributing flow to the wellfields. Calculations based on a uniform flow equation provided a preliminary delineation of zones of contribution for the wellfields and ground-water time-of-travel contours. Limitations of the applied methods motivated the design of a more rigorous hydrogeologic investigation.

Broshears, R.E.; Connell, J.F.; Short, N.C.

1991-01-01

251

Motion of Pacific mantle plumes  

NASA Astrophysics Data System (ADS)

The Hawaiian--Emperor hotspot chain, and its distinctive bend at 47 Ma, have figured prominently in the development of ideas on the nature of mantle plumes, plate motion, and frames of reference. However, paleomagnetic data from Ocean Drilling Program (ODP) Leg 197, together with results from plate circuit and geodynamic modeling studies, indicate southward motion of the Hawaiian hotspot during formation of the Emperor Seamounts. These analyses confirm the idea that mantle plumes should be influenced by mantle flow, and that such motion must be considered when constructing frames of reference for plate motion. An important corollary of this finding on hotspot motion is that long-term polar wander of Earth, which has been inaccurately assessed by viewing paleomagnetic data in a fixed hotspot reference frame, has been far less than previously thought. Here we extend the ODP Leg 197 analysis in three ways. We examine i. paleomagnetic data and their uncertainties relative to volcanic propagation rates; ii. consistency tests of plate circuit models and global paleomagnetic data and iii. intra-basin motion of plumes through new analyses of Late Cretaceous lavas from New Zealand. The first analysis suggests that while Late Cretaceous--Paleogene hotspot motion was the dominant factor in forming the Emperor track (and thus the famous bend morphology), smaller- scale plate motion changes might still be preserved in the track. The second set of analyses help point to deficiencies in the global paleomagnetic data set, whereas the third highlights that motion between groups of hotspots is a dominant feature during mid-Cretaceous to Paleogene times.

Cottrell, R. D.; Tarduno, J. A.; Doubrovine, P. V.

2007-12-01

252

Monitoring spatio-temporal variability of the Adour River turbid plume (Bay of Biscay, France) with MODIS 250-m imagery  

NASA Astrophysics Data System (ADS)

Increased loads of land-based pollutants through river plumes are a major threat to the coastal water quality, ecosystems and sanitary heath. Identifying the coastal areas impacted by potentially polluted freshwaters is necessary to inform management policies and prevent degradation of the coastal environment. This study presents the first monitoring of the Adour River turbid plume (south-eastern Bay of Biscay, France) using multi-annual MODIS data. Satellite data are processed using a regional algorithm that allows quantifying and mapping suspended matter in coastal waters. The results are used to investigate the spatial and temporal variability of the Adour River turbid plume and to identify the risk of exposure of coastal ecosystems to the turbid plume waters. Changes in river plume orientation and spatial extent as well as suspended matter discharged through the river are correlated to the main hydro-climatic forcings acting in the south-eastern Bay of Biscay. The Adour River turbid plume is shown to be a highly reactive system mainly controlled by the river discharge rates and modulated by the wind changes. Despite the relatively small size of the Adour River, the Adour River turbid plume can have a non-negligible impact on the water quality of the southern Bay of Biscay and the MSM and associated contaminants/nutrients transported within the Adour turbid river plume have the potential to be disseminated far away along the northern shoreline or offshore. The main areas of influence of the river plume are defined over multi-annual (3 years) and seasonal periods. The results presented in this study show the potential of 250-m MODIS images to monitor small river plumes systems and support management and assessment of the water quality in the south-eastern Bay of Biscay.

Petus, Caroline; Marieu, Vincent; Novoa, Stefani; Chust, Guillem; Bruneau, Nicolas; Froidefond, Jean-Marie

2014-02-01

253

Statistical analysis of ground-water contamination at the alert apron and northern landfill areas of Wurtsmith AFB, Michigan. Final report  

Microsoft Academic Search

Two plumes of contamination are analyzed to determine their extent, composition, and movement. The large number of ground-water monitoring wells sampled over the past eight years at Wurtsmith AFB allow this analysis to be performed directly from empirical data, with minimal assumptions about solute transport mechanisms. Conclusions are drawn about the likely sources of contamination in the two plumes, the

P. Hunter; S. Naber; J. Verducci

1988-01-01

254

Imaging and target volume delineation in glioma.  

PubMed

Here we review current practices in target volume delineation for radical radiotherapy planning for gliomas. Current radiotherapy planning margins for glioma are informed by historic data of recurrence patterns using radiological imaging or post-mortem studies. Radiotherapy planning for World Health Organization grade II-IV gliomas currently relies predominantly on T1-weighted contrast-enhanced magnetic resonance imaging (MRI) and T2/fluid-attenuated inversion recovery sequences to identify the gross tumour volume (GTV). Isotropic margins are added empirically for each tumour type, usually without any patient-specific individualisation. We discuss novel imaging techniques that have the potential to influence radiotherapy planning, by improving definition of the tumour extent and its routes of invasion, thus modifying the GTV and allowing anisotropic expansion to a clinical target volume better reflecting areas at risk of recurrence. Identifying the relationships of tumour boundaries to important white matter pathways and eloquent areas of cerebral cortex could lead to reduced normal tissue complications. Novel magnetic resonance approaches to identify tumour extent and invasion include: (i) diffusion-weighted magnetic resonance metrics; (ii) diffusion tensor imaging; and (iii) positron emission tomography, using radiolabelled amino acids methyl-11C-L-methionine and 18F-fluoroethyltyrosine. Novel imaging techniques may also have a role together with clinical characteristics and molecular genetic markers in predicting response to therapy. Most significant among these techniques is dynamic contrast-enhanced MRI, which uses dynamic acquisition of images after injection of intravenous contrast. A number of studies have identified changes in diffusion and microvascular characteristics occurring during the early stages of radiotherapy as powerful predictive biomarkers of outcome. PMID:24824451

Whitfield, G A; Kennedy, S R; Djoukhadar, I K; Jackson, A

2014-07-01

255

Inorganic Contaminant Fate Assessment in Zero-Valent Iron Treatment Walls  

Microsoft Academic Search

This article discusses the fate assessment of several inorganic contaminants in zero-valent iron treatment walls used for the cleanup of acidic plumes and the prevention of groundwater contamination in active or abandoned mixed sulphide and coal mining sites. The fate assessment of contaminants provides useful information for potential forensics investigations carried out in affected mining and waste disposal sites. Laboratory

Kostas Komnitsas; Georgios Bartzas; Ioannis Paspaliaris

2006-01-01

256

Complexity of Groundwater Contaminants at DOE Sites  

SciTech Connect

The U.S. Department of Energy (DOE) is responsible for the remediation and long-term stewardship of one of the world's largest groundwater contamination portfolios, with a significant number of plumes containing various contaminants, and considerable total mass and activity. As of 1999, the DOE's Office of Environmental Management was responsible for remediation, waste management, or nuclear materials and facility stabilization at 144 sites in 31 states and one U.S. territory, out of which 109 sites were expected to require long-term stewardship. Currently, 19 DOE sites are on the National Priority List. The total number of contaminated plumes on DOE lands is estimated to be 10,000. However, a significant number of DOE sites have not yet been fully characterized. The most prevalent contaminated media are groundwater and soil, although contaminated sediment, sludge, and surface water also are present. Groundwater, soil, and sediment contamination are present at 72% of all DOE sites. A proper characterization of the contaminant inventory at DOE sites is critical for accomplishing one of the primary DOE missions -- planning basic research to understand the complex physical, chemical, and biological properties of contaminated sites. Note that the definitions of the terms 'site' and 'facility' may differ from one publication to another. In this report, the terms 'site,' 'facility' or 'installation' are used to identify a contiguous land area within the borders of a property, which may contain more than one plume. The term 'plume' is used here to indicate an individual area of contamination, which can be small or large. Even though several publications and databases contain information on groundwater contamination and remediation technologies, no statistical analyses of the contaminant inventory at DOE sites has been prepared since the 1992 report by Riley and Zachara. The DOE Groundwater Data Base (GWD) presents data as of 2003 for 221 groundwater plumes at 60 DOE sites and facilities. Note that Riley and Zachara analyzed the data from only 18 sites/facilities including 91 plumes. In this paper, we present the results of statistical analyses of the data in the GWD as guidance for planning future basic and applied research of groundwater contaminants within the DOE complex. Our analyses include the evaluation of a frequency and ranking of specific contaminants and contaminant groups, contaminant concentrations/activities and total contaminant masses and activities. We also compared the results from analyses of the GWD with those from the 1992 report by Riley and Zachara. The difference between our results and those summarized in the 1992 report by Riley and Zachara could be caused by not only additional releases, but also by the use of modern site characterization methods, which more accurately reveal the extent of groundwater contamination. Contaminated sites within the DOE complex are located in all major geographic regions of the United States, with highly variable geologic, hydrogeologic, soil, and climatic conditions. We assume that the information from the 60 DOE sites included in the GWD are representative for the whole DOE complex. These 60 sites include the major DOE sites and facilities, such as Rocky Flats Environmental Technology Site, Colorado; Idaho National Laboratory, Idaho; Savannah River Site, South Carolina; Oak Ridge Reservation, Tennessee; and Hanford Reservation, Washington. These five sites alone ccount for 71% of the value of the remediation work.

Hazen, T.C.; Faybishenko, B.; Jordan, P.

2010-12-03

257

The plume variation at Enceladus  

NASA Astrophysics Data System (ADS)

It has been nine years since the discovery of the Enceladus plume, while its variation within this time is still under debate. A recent study has proposed that the vent intensity depends on the moon-Saturn distance. In our study we use a different data set to investigate this variation, and also check its co-relationship with other orbital characters. Between 2005 and 2012, Cassini has made 20 close flybys around Enceladus. Its plasma instrument has recorded the ambient magnetospheric plasma density, while its magnetometers have recorded the change in magnetic field by particle pickup. Unlike particle detectors that measure the in situ density along the path, or imagers that measure the vent temperature, the magnetometer measures the magnetic field, which provides the total momentum exchange in the whole interaction region. We use the magnetometer data and ambient plasma data along these 20 flybys, assisted with our MHD model, to determine the time variation of the total plume ejecta during these 8 years.

Jia, Ying-Dong; Russell, Christopher; Khurana, Krishan

2014-05-01

258

Space shuttle contamination due to backflow from control motor exhaust  

NASA Technical Reports Server (NTRS)

Spacecraft contamination of the space shuttle orbiter and accompanying Spacelab payloads is studied. The scattering of molecules from the vernier engines and flash evaporator nozzle after impingement on the orbiter wing surfaces, and the backflow of molecules out of the flash evaporator nozzle plume flow field due to intermolecular collisions in the plume are the problems discussed. A method was formulated for dealing with these problems, and detailed results are given.

Robertson, S. J.; Chan, S. T. K.; Lee, A. L.

1976-01-01

259

Preliminary far-field plume sputtering characterization of the Stationary Plasma Thruster (SPT-100)  

NASA Technical Reports Server (NTRS)

For electric propulsion devices to be considered for use on communications satellites, integration impacts must be examined in detail. Two phenomena of concern associated with highly energetic plumes are contamination via sputtered material from the thruster and sputter erosion of downstream surfaces. In order to characterize the net effect of both phenomena, an array of witness plates were mounted in several types of holders and were exposed to the SPT-100 thruster plume for 50 hours. Surface analysis of the witness plates revealed that in the most energetic regions of the plume, there was a net removal of material from the samples facing the thruster. In the peripheral regions, net deposits were observed and characterized by the changes in optical properties of these samples. Changes in surface properties of samples located in collimators were within experimental uncertainty.

Pencil, Eric J.

1994-01-01

260

VISUAL PLUMES MIXING ZONE MODELING SOFTWARE  

EPA Science Inventory

The US Environmental Protection Agency has a history of developing plume models and providing technical assistance. The Visual Plumes model (VP) is a recent addition to the public-domain models available on the EPA Center for Exposure Assessment Modeling (CEAM) web page. The Wind...

261

Distant Plume from Puhi-o-Kalaikini  

USGS Multimedia Gallery

The plume from the Puhi-o-Kalaikini ocean entry is easily visible from Highway 130, on the hill descending towards Kalapana. Just in front of the ocean entry plume, the houses of Kalapana Gardens subdivision can be seen on the 1990 lava flows....

262

PLUME DEVELOPMENT USING LAGRANGIAN MARKER METHOD  

EPA Science Inventory

Currents as a function of wind were calculated by a depth integrated model of Lake Superior. Using the calculated currents, the development of large turbidity plume was numerically simulated. Good agreement between the simulated plume, remote sensing, and ground truth data provid...

263

Seismic implications of mantle wedge plumes  

Microsoft Academic Search

We use a coupled petrological–thermomechanical model to investigate the dynamical effects of metamorphic reactions and melting on the seismic structure of thermal–chemical plumes beneath volcanic arcs. Plume generation is driven by the subduction of buoyant crustal rocks and expulsion of aqueous slab fluids that causes hydration and partial melting of the mantle wedge. The model demonstrates two chemically distinct types

Taras V. Gerya; James A. D. Connolly; David A. Yuen; Weronika Gorczyk; Allison M. Capel

2006-01-01

264

Endothermic and exothermic chemically reacting plumes  

Microsoft Academic Search

We develop a model for a turbulent plume in an unbounded ambient that takes into account a general exothermic or endothermic chemical reaction. These reactions can have an important effect on the plume dynamics since the entrainment rate, which scales with the vertical velocity, will be a function of the heat release or absorption. Specifically, we examine a second-order non-reversible

Devin T. Conroy; Stefan G. Llewellyn Smith

2008-01-01

265

Chemical Source Classification in Naturally Turbulent Plumes  

E-print Network

Chemical Source Classification in Naturally Turbulent Plumes Tim C. Pearce,*, Jing Gu, and Eric.O.S., 10 Avenue Didier Daurat, 31400 Toulouse, France The spatiotemporal dynamics of chemical plumes in natural environments imposes complex time-varying re- sponses on chemical detectors, challenging the use

Pearce, Tim C.

266

Plume persistence caused by back diffusion from thin clay layers in a sand aquifer following TCE source-zone hydraulic isolation  

Microsoft Academic Search

This paper concludes that back diffusion from one or a few thin clayey beds in a sand aquifer can cause contaminant persistence above MCLs in a sand aquifer long after the source zone initially causing the plume is isolated or removed. This conclusion is based on an intensive case study of a TCE contaminated site in Florida, with the processes

Beth L. Parker; Steven W. Chapman; Martin A. Guilbeault

2008-01-01

267

Mapping Pollution Plumes in Areas Impacted by Hurricane Katrina With Imaging Spectroscopy  

NASA Astrophysics Data System (ADS)

New Orleans endured flooding on a massive scale subsequent to Hurricane Katrina in August of 2005. Contaminant plumes were noticeable in satellite images of the city in the days following flooding. Many of these plumes were caused by oil, gasoline, and diesel that leaked from inundated vehicles, gas stations, and refineries. News reports also suggested that the flood waters were contaminated with sewage from breached pipes. Effluent plumes such as these pose a potential health hazard to humans and wildlife in the aftermath of hurricanes and potentially from other catastrophic events (e.g., earthquakes, shipping accidents, chemical spills, and terrorist attacks). While the extent of effluent plumes can be gauged with synthetic aperture radar and broad- band visible-infrared images (Rykhus, 2005) (e.g., Radarsat and Landsat ETM+) the composition of the plumes could not be determined. These instruments lack the spectral resolution necessary to do chemical identification. Imaging spectroscopy may help solve this problem. Over 60 flight lines of NASA Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data were collected over New Orleans, the Mississippi Delta, and the Gulf Coast from one to two weeks after Katrina while the contaminated water was being pumped out of flooded areas. These data provide a unique opportunity to test if imaging spectrometer data can be used to identify the chemistry of these flood-related plumes. Many chemicals have unique spectral signatures in the ultraviolet to near-infrared range (0.2 - 2.5 microns) that can be used as fingerprints for their identification. We are particularly interested in detecting thin films of oil, gasoline, diesel, and raw sewage suspended on or in water. If these materials can be successfully differentiated in the lab then we will use spectral-shape matching algorithms to look for their spectral signatures in the AVIRIS data collected over New Orleans and other areas impacted by Katrina. If imaging spectroscopy can be used to identify plume composition on a regional scale than this information would help emergency personnel prioritize evacuations, help government agencies formulate cleanup strategies, and help ecologists assess the potential damage to wetlands and wildlife. This work could be the start of a new application of hyperspectral data for world-wide monitoring of spills from space-based imaging spectrometers. AVIRIS data used to test our method were corrected for solar flux, atmospheric absorptions, and scattering using the Atmospheric CORrection Now (ACORN) radiative transfer algorithm and residual artifacts were removed using ground spectra of a concrete runway at the Gulfport Airport in Mississippi. The resulting apparent reflectance data were mapped for spectral signatures of pollution plumes and results will be presented.

Swayze, G. A.; Furlong, E. T.; Livo, K. E.

2007-12-01

268

Plume dispersion in a nocturnal drainage wind  

NASA Astrophysics Data System (ADS)

A series of tracer experiments were conducted under nocturnal drainage wind conditions in a complex terrain setting in the Piceance Basin of western Colorado. Concurrent meteorological information including profiles of wind and temperature as well as gross turbulence fluctuations from fixed 2-m stations provided the basis to test plume growth and dilution prescriptions for this moderately complex site. Plume parameters exhibited slightly greater diffusion than would be indicated by simple stability-based prediction methods or the gross turbulence indicators. Two terrain-related mechanisms appear to contribute to the development of the plume. A meandering component immediately downwind of the confluence of two valleys gives the appearance of an abnormally wide time-integrated plume. Further downstream the mean wind direction stabilizes and the plume dimension reflects diffusive spread due to small-scale turbulence.

Barr, Sumner; Kyle, Thomas G.; Clements, William E.; Sedlacek, William

269

System for the removal of contaminant soil-gas vapors  

DOEpatents

A system extracts contaminated vapors from soil or other subsurface regions by using changes in barometric pressure to operate sensitive check valves that control air entry and removal from wells in the ground. The system creates an efficient subterranean flow of air through a contaminated soil plume and causes final extraction of the contaminants from the soil to ambient air above ground without any external energy sources. 4 figs.

Weidner, J.R.; Downs, W.C.; Kaser, T.G.; Hall, H.J.

1997-12-16

270

System for the removal of contaminant soil-gas vapors  

DOEpatents

A system extracts contaminated vapors from soil or other subsurface regions by using changes in barometric pressure to operate sensitive check valves that control air entry and removal from wells in the ground. The system creates an efficient subterranean flow of air through a contaminated soil plume and causes final extraction of the contaminants from the soil to ambient air above ground without any external energy sources.

Weidner, Jerry R. (Iona, ID); Downs, Wayne C. (Sugar City, ID); Kaser, Timothy G. (Ammon, ID); Hall, H. James (Idaho Falls, ID)

1997-01-01

271

Remediation of overlapping benzene/MTBE and MTBE-only plumes: A case study  

SciTech Connect

Two overlapping dissolved hydrocarbon plumes were identified in the shallow water-bearing zone at a commercial vehicle service and fueling facility. Plume 1 originated from a pre-1993 gasoline product line/dispenser leak. This plume contained a relatively common mix of benzene, toluene, ethylbenzene, xylenes (BTEX), and methyl tert-butyl ether (MTBE); benzene and MTBE were identified as the Plume 1 contaminants of concern based on their detection at approximately 200 {mu}g/l each, which exceeded regulatory guidance. Plume 2, which was detected in the tank cavity during UST removal, resulted from gasoline line leaks/underground storage tank overfills. Although the majority of impacted soils in both the dispenser and tank cavity areas were removed during UST excavation, rainfall during impacted soil removal mobilized the MTBE contained in the soils to groundwater. As a result, Plume 2 contained approximately 900 {mu}g/l MTBE while BTEX compounds were non-detect. Although the impacted zone sustained an approximate yield of only 0.3 gallon per minute, Pennsylvania regulations dictate that this zone must be treated as an aquifer. The failure of remediating gasoline plumes using pump-and-treat has been predominantly due to BTEX`s tendency to adsorb onto soil, creating a residual-phase product layer which acts as a continuing source of dissolved-phase BTEX. Based on this experience, most groundwater and remediation professionals reject pump-and-treat as a viable remedial option, except in situations where controlling groundwater movement is the predominant goal.

Carpenter, P.L. [TolTest, Inc., Pittsburgh, PA (United States); Vinch, C.A. [Ryder Transportation Services, Lawrenceville, NJ (United States)

1997-12-31

272

Dynamics and Deposits of Coignimbrite Plumes  

NASA Astrophysics Data System (ADS)

Fine ash in the atmosphere poses a significant hazard, with potentially disastrous consequences for aviation and, on deposition, health and infrastructure. Fine-grained particles form a large proportion of ejecta in Plinian volcanic clouds. However, another common, but poorly studied phenomena exists whereby large amounts of fine ash are injected into the atmosphere. Coignimbrite plumes form as material is elutriated from the top of pyroclastic density currents. The ash in these plumes is considerably finer grained than that in Plinian plumes and can be distributed over thousands of kilometres in the atmosphere. Despite their significance, very little is known regarding coignimbrite plume formation and dispersion, predominantly due to the poor preservation of resultant deposits. As a result, consequences of coignimbrite plume formation are usually overlooked when conducting hazard and risk analysis. In this study, deposit characteristics and numerical models of plumes are combined to investigate the conditions required for coignimbrite plume formation. Coignimbrite deposits from the Campanian Ignimbrite eruption (Magnitude 7.7, 39 ka) are well sorted and very fine, with a mode of between 30 and 50 microns, and a significant component of respirable ash (less than 10 microns). Analogous distributions are found for coignimbrite deposits from Tungurahua 2006 and Volcan de Colima (2004-2006), amongst others, regardless of magnitude, type or chemistry of eruption. These results indicate that elutriation processes are the dominant control on coignimbrite grainsize distribution. To further investigate elutriation and coignimbrite plume dynamics, the numerical plume model of Bursik (2001) is applied. Model sensitivity analysis demonstrates that neutral buoyancy conditions (required for the formation of the plume) are controlled by a balance between temperature and gas mass flux in the upper most parts of the pyroclastic density current. In addition, results emphasize the importance of entrainment into the established plume, a process that is still poorly defined. The numerical results, and the consistent fine grained nature of ash in the deposits, highlight the importance of physical dynamics in the parent pyroclastic density currents for coignimbrite plume formation and stress the need for tailored methods to investigate hazard and risk from such events. Bursik, M. Effect of wind on the rise height of volcanic plumes. Geophysical Research Letters, 28(18), 3621-3624, 2001.

Engwell, Samantha; de'Michieli Vitturi, Mattia; Esposti Ongaro, Tomaso; Neri, Augusto

2014-05-01

273

Jurisdictional wetland delineation in the Texas Gulf Coast Prairie utilizing aerial photography  

E-print Network

instrument and entered into a GIS. Onsite delineations were performed using a standard technique for wetland delineations based on the 1987 Corps of Engineers Wetland Delineation Manual. Area calculations were obtained for the remotely sensed wetlands, the...

Watson, Samuel Jewell

1997-01-01

274

Linear Spectral Analysis of Plume Emissions Using an Optical Matrix Processor  

NASA Technical Reports Server (NTRS)

Plume spectrometry provides a means to monitor the health of a burning rocket engine, and optical matrix processors provide a means to analyze the plume spectra in real time. By observing the spectrum of the exhaust plume of a rocket engine, researchers have detected anomalous behavior of the engine and have even determined the failure of some equipment before it would normally have been noticed. The spectrum of the plume is analyzed by isolating information in the spectrum about the various materials present to estimate what materials are being burned in the engine. Scientists at the Marshall Space Flight Center (MSFC) have implemented a high resolution spectrometer to discriminate the spectral peaks of the many species present in the plume. Researchers at the Stennis Space Center Demonstration Testbed Facility (DTF) have implemented a high resolution spectrometer observing a 1200-lb. thrust engine. At this facility, known concentrations of contaminants can be introduced into the burn, allowing for the confirmation of diagnostic algorithms. While the high resolution of the measured spectra has allowed greatly increased insight into the functioning of the engine, the large data flows generated limit the ability to perform real-time processing. The use of an optical matrix processor and the linear analysis technique described below may allow for the detailed real-time analysis of the engine's health. A small optical matrix processor can perform the required mathematical analysis both quicker and with less energy than a large electronic computer dedicated to the same spectral analysis routine.

Gary, C. K.

1992-01-01

275

Delineating the Citation Impact of Scientific Discoveries Chaomei Chen  

E-print Network

Delineating the Citation Impact of Scientific Discoveries Chaomei Chen Drexel University 3141 introduce an innovative visual analytic approach to integrate microscopic and macroscopic perspectives unexpected phrases extracted from unstructured text of titles and abstracts at the microscopic level

Chen, Chaomei

276

1. PHOTOCOPY OF HISTORIC DRAWING OF SHIP SECTION, UNKNOWN DELINEATOR ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

1. PHOTOCOPY OF HISTORIC DRAWING OF SHIP SECTION, UNKNOWN DELINEATOR AND DATE, SOURCE: BISHOP MUSEUM, HONOLULU, HI. - Ship "Falls of Clyde", Hawaii Maritime Center,Pier 7, Honolulu, Honolulu County, HI

277

1. Photocopy of architectural drawing Delineated by Royal Danish Academy ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

1. Photocopy of architectural drawing Delineated by Royal Danish Academy of Fine Arts (Kunstakademiets) Copenhagen, Denmark, 1961 STREET ELEVATIONS - Strandgade 14-17 (House), 14-17 Strand Street, Frederiksted, St. Croix, VI

278

2. Photocopy of a measured drawing (original delineated by the ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

2. Photocopy of a measured drawing (original delineated by the Royal Danish Academy of Fine Arts (Kunstakademiets), Copenhagen, Denmark, 1961) PLANS OF FIRST AND SECOND FLOORS - Kongensgade 56-57 (House), 56-57 King Street, Christiansted, St. Croix, VI

279

2. Photocopy of a measured drawing (original delineated the Royal ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

2. Photocopy of a measured drawing (original delineated the Royal Danish Academy of Fine Arts (Kunstakademiets), Copenhagen, Denmark, 1961) FRONT (KING STREET) ELEVATION AND PLANS OF FIRST AND SECOND FLOORS - Kongensgade 58 (House), 58 King Street, Christiansted, St. Croix, VI

280

1. Photocopy of a measured drawing (original delineated by the ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

1. Photocopy of a measured drawing (original delineated by the Royal Danish Academy of Fine Arts (Kunstakademiets), Copenhagen Denmark, 1961) PLANS OF FIRST AND SECOND FLOORS - Kongensgade 21 (House), Christiansted, St. Croix, VI

281

1. Photocopy of measured drawing (original delineated by the Royal ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

1. Photocopy of measured drawing (original delineated by the Royal Danish Academy of Fine Arts (Kunstakademiets), Copenhagen, Denmark, 1961) Photographer and date of photograph unknown FRONT (STREET) ELEVATION - Dronningens Tvaergade 42 (House), 42 Queens Cross Street, Christiansted, St. Croix, VI

282

1. Photocopy of measured drawing (original delineated by the Royal ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

1. Photocopy of measured drawing (original delineated by the Royal Danish Academy of Fine Arts (Kunstakademiets), Copenhagen, Denmark, 1961) Photographer and date of photograph unknown HOSPITALSGADE (FRONT) ELEVATION - Hospitalsgade 23 (House), 23 Hospital Street, Christiansted, St. Croix, VI

283

Recognition of Road Contours Using Delineators at Night  

NASA Astrophysics Data System (ADS)

Drivers of vehicles focus their gaze in the direction of movement, driver guesses an optimum route using the white road line and the delineators. However, the range that can be clearly seen in the headlights is limited, it is difficult to guess the optimum route. This paper proposes a method that estimate road contour using delineators. The road contours are estimated from the 3D positions of delineators located on the sides of roads, which are extracted using a circle detection filter. Then, clothoid curve is applied to the delineators and the parameters of clothoid curve are obtained. This classifies the parameter into four kinds of curves using support vector machine. In simulation experiment, we create a virtual road. A classification rate was 86.9 %. Our method was able to classify the road contour by high accuracy.

Shimizu, Shoichi; Fujiyoshi, Hironobu; Sakai, Hiroshi; Kanade, Takeo; Iwahori, Yuji

284

Radiation from advanced solid rocket motor plumes  

NASA Technical Reports Server (NTRS)

The overall objective of this study was to develop an understanding of solid rocket motor (SRM) plumes in sufficient detail to accurately explain the majority of plume radiation test data. Improved flowfield and radiation analysis codes were developed to accurately and efficiently account for all the factors which effect radiation heating from rocket plumes. These codes were verified by comparing predicted plume behavior with measured NASA/MSFC ASRM test data. Upon conducting a thorough review of the current state-of-the-art of SRM plume flowfield and radiation prediction methodology and the pertinent data base, the following analyses were developed for future design use. The NOZZRAD code was developed for preliminary base heating design and Al2O3 particle optical property data evaluation using a generalized two-flux solution to the radiative transfer equation. The IDARAD code was developed for rapid evaluation of plume radiation effects using the spherical harmonics method of differential approximation to the radiative transfer equation. The FDNS CFD code with fully coupled Euler-Lagrange particle tracking was validated by comparison to predictions made with the industry standard RAMP code for SRM nozzle flowfield analysis. The FDNS code provides the ability to analyze not only rocket nozzle flow, but also axisymmetric and three-dimensional plume flowfields with state-of-the-art CFD methodology. Procedures for conducting meaningful thermo-vision camera studies were developed.

Farmer, Richard C.; Smith, Sheldon D.; Myruski, Brian L.

1994-01-01

285

No Ocean Source for the Enceladus Plumes  

NASA Astrophysics Data System (ADS)

One surprising discovery of the Cassini mission to Saturn has been the presence of geyser-like plumes at the south pole of the icy moon Enceladus ejecting >300; kg/s of water into Saturn's magnetosphere. In situ and remote observations (Waite et al. 2006; Hansen et al. 2006) have shown that the primary plume constituent is H2O, and thermal measurements indicate intense heating in cracks believed to be plume vents on the surface (Spencer et al. 2006). These observations have led to speculation that the plumes are fed from a liquid water reservoir beneath Enceladus' surface. We present results from an extremely sensitive, high-resolution spectroscopic search using the Keck and Anglo-Australian Telescopes which place a stringent upper limit on sodium emission in the Enceladus plumes. Large amounts of sodium would be expected if Enceladus' plume material were derived directly from a subsurface liquid reservoir in contact with rocky material. Chemical models predict that sodium would dissolve into such an ocean at mixing ratios relative to water of 10-4 to 10-1 (Zolotov et al., 2007). Our numerical plume models show that such high sodium concentrations would form a detectable torus encircling Saturn. Our detection upper limits fall orders of magnitude below these models, leading us to conclude that the Enceladus plumes do not originate in an ocean or sea. These observations support the alternative theories that the plumes are generated by shear heating of the icy crust resulting in sublimation or melting, or the decomposition of clathrates. This work has been supported by the NASA Postdoctoral Program and the NSF's Planetary Astronomy Program. References: Hansen et al., Science, 311, 1422, 2006. Spencer et al., Science, 311, 1401, 2006. Waite et al., Science, 311, 1419, 2006. Zolotov et al., Presented to the "Enceladus Focus Group Workshop," Boulder, CO, 2007.

Burger, Matthew H.; Schneider, N. M.; Johnson, R. E.; Kargel, J. S.; Schaller, E. L.; Brown, M. E.

2007-12-01

286

Delinating Thermohaline Double-Diffusive Rayleigh Regimes  

NASA Astrophysics Data System (ADS)

In natural systems, convective flow induced from density differences may occur in near-coastal aquifers, atmospheric boundary layers, oceanic streams or within the earth crust. Whether an initially stable, diffusive regime evolves into a convective (stable or chaotic) regime, or vice versa, depends on the system's framing boundary conditions. A conventional parameter to express the relation between diffusive and convective forces of such a density-driven regime is Rayleigh number (Ra). While most systems are mainly dominated by only a single significant driving force (i.e. only temperature or salinity), some systems need to consider two boundary processes (e.g. deep, thus warm, haline flow in porous media). In that case, a two-dimensional, 'double-diffusive' Rayleigh system can be defined. Nield (1998) postulated a boundary between diffusive and convective regime at RaT + RaC = 4pi^2 in the first quadrant (Q1), with Rayleigh numbers for temperature and concentration respectively. The boundary in the forth quadrant (Q4) could not exactly be determined, yet the approximate position estimated. Simulations with HydroGeoSphere (Therrien, 2010) using a vertical, quadratic, homogeneous, isotropic setup confirmed the existence of the 4pi^2-boundary and revealed additional regimes (diffusive, single-roll, double-roll, chaotic) in Q1. Also, non-chaotic, oscillating patterns could be identified in Q4. More detailed investigations with OpenGeoSys (Kolditz, 2012) confirmed the preceding HGS results, and, using a 1:10-scaled domain (height:length), uncovered even more distinctive regimes (diffusive, minimum ten roles, supposely up to 25 roles, and chaotic?) in Q1, while again, oscillating patterns were found in the transition zone between diffusive and chaotic regimes in Q4. Output of numerical simulations from Q1 and Q4 show the mentioned regimes (diffusive, stable-convective, stable-oscillatory, chaotic) while results are displayed in context of a possible delination between the regimes within the double-diffusive system and boundaries similar to the relation postulated by Nield (1998). Research on the existence of different regimes and the possiblity to predict and estimate a system's specific regime apriori (without numerical simulation) will aid in easy characterization of such thermohaline systems. Literature KOLDITZ, O., BAUER, S., BILKE, L., BÖTTCHER, N., DELFS, J. O., FISCHER, T., GÖRKE, U. J., ET AL. (2012). OPENGEOSYS: AN OPEN-SOURCE INITIATIVE FOR NUMERICAL SIMULATION OF THERMO-HYDRO-MECHANICAL/CHEMICAL (THM/C) PROCESSES IN POROUS MEDIA. ENVIRONMENTAL EARTH SCIENCES, 67(2), 589-599. DOI:10.1007/S12665-012-1546-X THERRIEN, R., MCLAREN, R.G., SUDICKY, E.A. AND PANDAY, S.M. (2010): HYDROGEOSPHERE--A THREE-DIMENSIONAL NUMERICAL MODEL DESCRIBING FULLY INTEGRATED SUBSURFACE AND SURFACE FLOW AND SOLUTE TRANSPORT; UNIVERSITÉ LAVAL AND UNIVERSITY OF WATERLOO, CANADA NIELD, D. A., & BEJAN, A. (1998). CONVECTION IN POROUS MEDIA (P. 546). SPRINGER.

Graf, T.; Walther, M.; Kolditz, O.; Liedl, R.

2013-12-01

287

Long-term natural attenuation of carbon and nitrogen within a groundwater plume after removal of the treated wastewater source  

USGS Publications Warehouse

Disposal of treated wastewater for more than 60 years onto infiltration beds on Cape Cod, Massachusetts produced a groundwater contaminant plume greater than 6 km long in a surficial sand and gravel aquifer. In December 1995 the wastewater disposal ceased. A long-term, continuous study was conducted to characterize the post-cessation attenuation of the plume from the source to 0.6 km downgradient. Concentrations and total pools of mobile constituents, such as boron and nitrate, steadily decreased within 1-4 years along the transect. Dissolved organic carbon loads also decreased, but to a lesser extent, particularly downgradient of the infiltration beds. After 4 years, concentrations and pools of carbon and nitrogen in groundwater were relatively constant with time and distance, but substantially elevated above background. The contaminant plume core remained anoxic for the entire 10-year study period; temporal patterns of integrated oxygen deficit decreased slowly at all sites. In 2004, substantial amounts of total dissolved carbon (7 mol C m-2) and fixed (dissolved plus sorbed) inorganic nitrogen (0.5 mol N m-2) were still present in a 28-m vertical interval at the disposal site. Sorbed constituents have contributed substantially to the dissolved carbon and nitrogen pools and are responsible for the long-term persistence of the contaminant plume. Natural aquifer restoration at the discharge location will take at least several decades, even though groundwater flow rates and the potential for contaminant flushing are relatively high.

Repert, D.A.; Barber, L.B.; Hess, K.M.; Keefe, S.H.; Kent, D.B.; LeBlanc, D.R.; Smith, R.L.

2006-01-01

288

The Use of Predictive Modeling in the Characterization and Remediation of the High Flux Beam Reactor Tritium Plume  

Microsoft Academic Search

Discovery of tritium in the groundwater near the Brookhaven National Laboratory High Flux Beam Reactor (HFBR) in January 1997 initiated an intense effort to locate its source, determine its extent, and implement remediation methods to mitigate its consequences. The tritium plume that resulted from the slow, long-term seepage of contaminated water from the HFBR spent fuel pool was the subject

W. Gunther; M. Hauptmann; T. Sullivan

2008-01-01

289

Digital filtering of plume emission spectra  

NASA Technical Reports Server (NTRS)

Fourier transformation and digital filtering techniques were used to separate the superpositioned spectral phenomena observed in the exhaust plumes of liquid propellant rocket engines. Space shuttle main engine (SSME) spectral data were used to show that extraction of spectral lines in the spatial frequency domain does not introduce error, and extraction of the background continuum introduces only minimal error. Error introduced during band extraction could not be quantified due to poor spectrometer resolution. Based on the atomic and molecular species found in the SSME plume, it was determined that spectrometer resolution must be 0.03 nm for SSME plume spectral monitoring.

Madzsar, George C.

1990-01-01

290

Digital filtering of plume emission spectra  

SciTech Connect

Fourier transformation and digital filtering techniques were used to separate the superpositioned spectral phenomena observed in the exhaust plumes of liquid propellant rocket engines. Space shuttle main engine (SSME) spectral data were used to show that extraction of spectral lines in the spatial frequency domain does not introduce error, and extraction of the background continuum introduces only minimal error. Error introduced during band extraction could not be quantified due to poor spectrometer resolution. Based on the atomic and molecular species found in the SSME plume, it was determined that spectrometer resolution must be 0.03 nm for SSME plume spectral monitoring.

Madzsar, G.C.

1990-07-01

291

Investigating In-Situ Mass Transfer Processes in a Groundwater U Plume Influenced by Groundwater-River Hydrologic and Geochemical Coupling (Invited)  

Microsoft Academic Search

The Hanford Integrated Field Research Challenge (IFRC) site is a DOE\\/BER-supported experimental and monitoring facility focused on multi-scale mass transfer processes (hanfordifc@pnl.gov). It is located within the footprint of a historic uranium (U) waste disposal pond that overlies a contaminated vadose zone and a 1 km+ groundwater U plume. The plume is under a regulatory clean-up mandate. The site is

J. M. Zachara

2009-01-01

292

Buoyant plumes with inertial and chemical reaction-driven forcing  

E-print Network

the plume head has risen to the top of a fluid filled tank leaving only a persistent conduit. Plume. The forced plumes were compositionally buoy- ant and were injected with inertial forcing into a fluid filled tank. The autocatalytic plumes were produced without mechanical forcing by buoyancy that was entirely

Morris, Stephen W.

293

Adaptive Management of Remediation Systems Under Uncertain Hydraulic Conductivity and Plume Distribution  

NASA Astrophysics Data System (ADS)

The optimal design and the management of pump-and-treat (PAT) remediation systems is generally tackled with the aid of combined simulation-optimization models to rank alternatives while considering management objectives and constraints. Since this process is typically carried out in an environment of uncertainties, our ability to determine cleanup policies that are cost optimal and reliable at the same time is in fact limited. In this work, we present a stochastic optimal control framework for assisting the management of the PAT cleanup of polluted shallow aquifers. Hydraulic conductivity distribution and dissolved contaminant plume location are considered as the uncertain parameters. The framework considers the subdivision of the cleanup horizon in a sequence of stress periods over which the pumping policy implemented at each stage is dynamically adjusted based on new information that has become available in the previous stages. In particular, we study the idea of monitoring the cumulative contaminant mass extracted from the installed recovery wells, and using these measurements to generate conditional realizations of the hydraulic conductivity field. These realizations are thus used to obtain a more accurate evaluation of the initial plume distribution, and modify accordingly the design of the PAT system for the remainder of the remedial process. The study indicates that measurements of contaminant mass extracted from pumping wells retain valuable information about the plume location and the spatial heterogeneity characterizing the hydraulic conductivity field. However, such an information may prove quite soft, particularly in the instances where recovery wells are installed in regions where contaminant concentration is low or zero. On the other hand, integrated solute mass meausurements may effectively allow for reducing parameter uncertainty and identifying the plume distribution if more recovery wells are available, in particular in the early stages of the cleanup process.

Bau, D. A.; Mayer, A. S.

2007-12-01

294

Behavior of a chlorinated ethene plume following source-area treatment with Fenton's reagent  

USGS Publications Warehouse

Monitoring data collected over a 6-year period show that a plume of chlorinated ethene-contaminated ground water has contracted significantly following treatment of the contaminant source area using in situ oxidation. Prior to treatment (1998), concentrations of perchloroethene (PCE) exceeded 4500 ??g/L in a contaminant source area associated with a municipal landfill in Kings Bay, Georgia. The plume emanating from this source area was characterized by vinyl chloride (VC) concentrations exceeding 800 ??g/L. In situ oxidation using Fenton's reagent lowered PCE concentrations in the source area below 100 ??g/L, and PCE concentrations have not rebounded above this level since treatment. In the 6 years following treatment, VC concentrations in the plume have decreased significantly. These concentration declines can be attributed to the movement of Fenton's reagent-treated water downgradient through the system, the cessation of a previously installed pump-and-treat system, and the significant natural attenuation capacity of this anoxic aquifer. While in situ oxidation briefly decreased the abundance and activity of microorganisms in the source area, this activity rebounded in <6 months. Nevertheless, the shift from sulfate-reducing to Fe(III)-reducing conditions induced by Fenton's treatment may have decreased the efficiency of reductive dechlorination in the injection zone. The results of this study indicate that source-area removal actions, particularly when applied to ground water systems that have significant natural attenuation capacity, can be effective in decreasing the areal extent and contaminant concentrations of chlorinated ethene plumes. Copyright ?? 2005 National Ground Water Association.

Chapelle, F.H.; Bradley, P.M.; Casey, C.C.

2005-01-01

295

Subsurface Contamination Focus Area technical requirements. Volume 1: Requirements summary  

SciTech Connect

This document summarizes functions and requirements for remediation of source term and plume sites identified by the Subsurface Contamination Focus Area. Included are detailed requirements and supporting information for source term and plume containment, stabilization, retrieval, and selective retrieval remedial activities. This information will be useful both to the decision-makers within the Subsurface Contamination Focus Area (SCFA) and to the technology providers who are developing and demonstrating technologies and systems. Requirements are often expressed as graphs or charts, which reflect the site-specific nature of the functions that must be performed. Many of the tradeoff studies associated with cost savings are identified in the text.

Nickelson, D.; Nonte, J.; Richardson, J.

1996-10-01

296

Plume Ascent Tracker: Interactive Matlab software for analysis of ascending plumes in image data  

NASA Astrophysics Data System (ADS)

This paper presents Matlab-based software designed to track and analyze an ascending plume as it rises above its source, in image data. It reads data recorded in various formats (video files, image files, or web-camera image streams), and at various wavelengths (infrared, visible, or ultra-violet). Using a set of filters which can be set interactively, the plume is first isolated from its background. A user-friendly interface then allows tracking of plume ascent and various parameters that characterize plume evolution during emission and ascent. These include records of plume height, velocity, acceleration, shape, volume, ash (fine-particle) loading, spreading rate, entrainment coefficient and inclination angle, as well as axial and radial profiles for radius and temperature (if data are radiometric). Image transformations (dilatation, rotation, resampling) can be performed to create new images with a vent-centered metric coordinate system. Applications may interest both plume observers (monitoring agencies) and modelers. For the first group, the software is capable of providing quantitative assessments of plume characteristics from image data, for post-event analysis or in near real-time analysis. For the second group, extracted data can serve as benchmarks for plume ascent models, and as inputs for cloud dispersal models. We here describe the software's tracking methodology and main graphical interfaces, using thermal infrared image data of an ascending volcanic ash plume at Santiaguito volcano.

Valade, S. A.; Harris, A. J. L.; Cerminara, M.

2014-05-01

297

Characterization of ozone plumes in eastern Germany  

NASA Astrophysics Data System (ADS)

During a photosmog period in summer 1993, several ozone plumes (enrichment of O3 of 10-45 ppb over levels of surrounding air masses) were observed in the southern part of eastern Germany. Analyses of the plumes for other species reveal that SO2, NOy, CO, and photochemically formed CH2O were enriched synchronously with O3. The measured enhancement factors SO2/CO and NOy/CO agree well with emission factors of local emission inquiries. The O3 production potential in the plumes must have originated from emissions from furnaces burning sulfur rich lignite coal under non-optimum conditions such as old power plants, industrial plants, and domestic water heating systems. The co-emission of VOC's with SO2 lead to the formation of O3 and CH2O. Most of the plumes seem to be less than one day old.

Klemm, O.; Werhahn, J.; Schaller, E.; Schlager, H.; Krautstrunk, M.

298

Simulation of plume dynamics using particle graphics  

NASA Astrophysics Data System (ADS)

To enhance the fidelity of numerical flow field (plume) imagery in hardware-in-the-loop (HIL) systems, new methods using particle system graphics have been developed. To render infrared (IR) images that are consistent with the underlying physical phenomenology, techniques for particle placement, pixel rasterization and drawing were developed and implemented in computer software. The software was integrated into an existing HIL scene generator and used to demonstrate several new capabilities. Moving particle systems were used to depict the internal flow and turbulence common to plumes. Persistent particle systems were used to depict the trail of hot gas and particulates left behind typical plumes. The addition of plume dynamic behaviors such as these can potentially improve HIL systems and, as a result, improve the testing of seekers and other weapon systems.

Tourtellott, John; Coker, Charles F.; Crow, Dennis R.

2000-07-01

299

Plume reflection in pulsed laser deposition  

NASA Astrophysics Data System (ADS)

Plume reflection has been studied as a possibility for depositing on a direction perpendicular to target, convenient for manipulation of big size substrates and for avoiding the presence of droplets on film surface. Plume behaviour during reflection on a 45 degree(s) oriented plane surface has been monitored by a high- speed camera. Thin film, deposited by reflected plume, has been analysed by scanning electron microscopy (SEM) and atomic forces microscopy (AFM). Comparing with a standard deposition a 1-2 order of magnitude improvement for film roughness (RMS) has been noticed at the expense of one order of magnitude diminuation of deposition rate. The results have shown significant dependencies of film thickness and surface quality on plume reflection angle. Some aspects of big particles movement in deposition process are also presented.

Marcu, Aurelian; Grigoriu, Constantin; Jiang, Weihua; Yatsui, Kiyoshi

2002-08-01

300

A method to attenuate U(VI) mobility in acidic waste plumes using humic acids  

SciTech Connect

Acidic uranium (U) contaminated plumes have resulted from acid-extraction of plutonium during the Cold War and from U mining and milling operations. A sustainable method for in-situ immobilization of U under acidic conditions is not yet available. Here, we propose to use humic acids (HAs) for in-situ U immobilization in acidic waste plumes. Our laboratory batch experiments show that HA can adsorb onto aquifer sediments rapidly, strongly and practically irreversibly. Adding HA greatly enhanced U adsorption capacity to sediments at pH below 5.0. Our column experiments using historically contaminated sediments from the Savannah River Site under slow flow rates (120 and 12 m/y) show that desorption of U and HA were non-detectable over 100 pore-volumes of leaching with simulated acidic groundwaters. Upon HA-treatment, 99% of the contaminant [U] was immobilized at pH < 4.5, compared to 5% and 58% immobilized in the control columns at pH 3.5 and 4.5, respectively. These results demonstrated that HA-treatment is a promising in-situ remediation method for acidic U waste plumes. As a remediation reagent, HAs are resistant to biodegradation, cost effective, nontoxic, and easily introducible to the subsurface.

Wan, J.; Dong, W.; Tokunaga, T.K.

2011-02-01

301

Nuclear thermal rocket plume interactions with spacecraft. Final report  

SciTech Connect

This is the first study that has treated the Nuclear Thermal Rocket (NTR) effluent problem in its entirety, beginning with the reactor core, through the nozzle flow, to the plume backflow. The summary of major accomplishments is given below: (1) Determined the NTR effluents that include neutral, ionized and radioactive species, under typical NTR chamber conditions. Applied an NTR chamber chemistry model that includes conditions and used nozzle geometries and chamber conditions typical of NTR configurations. (2) Performed NTR nozzle flow simulations using a Navier-Stokes solver. We assumed frozen chemistry at the chamber conditions and used nozzle geometries and chamber conditions typical of NTR configurations. (3) Performed plume simulations using a Direct Simulation Monte Carlo (DSMC) code with chemistry. In order to account for radioactive trace species that may be important for contamination purposes we developed a multi-weighted DSMC methodology. The domain in our simulations included large regions downstream and upstream of the exit. Inputs were taken from the Navier-Stokes solutions.

Mauk, B.H. [Johns Hopkins Univ., Laurel, MD (United States); Gatsonis, N.A.; Buzby, J.; Yin, X. [Worcester Polytechnic Inst., MA (United States). Mechanical Engineering Department

1997-05-01

302

A modeling of buoyant gas plume migration  

SciTech Connect

This work is motivated by the growing interest in injecting carbon dioxide into deep geological formations as a means of avoiding its atmospheric emissions and consequent global warming. Ideally, the injected greenhouse gas stays in the injection zone for a geologic time, eventually dissolves in the formation brine and remains trapped by mineralization. However, one of the potential problems associated with the geologic method of sequestration is that naturally present or inadvertently created conduits in the cap rock may result in a gas leakage from primary storage. Even in a supercritical state, the carbon dioxide viscosity and density are lower than those of the formation brine. Buoyancy tends to drive the leaked CO{sub 2} plume upward. Theoretical and experimental studies of buoyancy-driven supercritical CO{sub 2} flow, including estimation of time scales associated with plume evolution and migration, are critical for developing technology, monitoring policy, and regulations for safe carbon dioxide geologic sequestration. In this study, we obtain simple estimates of vertical plume propagation velocity taking into account the density and viscosity contrast between CO{sub 2} and brine. We describe buoyancy-driven countercurrent flow of two immiscible phases by a Buckley-Leverett type model. The model predicts that a plume of supercritical carbon dioxide in a homogeneous water-saturated porous medium does not migrate upward like a bubble in bulk water. Rather, it spreads upward until it reaches a seal or until it becomes immobile. A simple formula requiring no complex numerical calculations describes the velocity of plume propagation. This solution is a simplification of a more comprehensive theory of countercurrent plume migration (Silin et al., 2007). In a layered reservoir, the simplified solution predicts a slower plume front propagation relative to a homogeneous formation with the same harmonic mean permeability. In contrast, the model yields much higher plume propagation estimates in a high-permeability conduit like a vertical fracture.

Silin, D.; Patzek, T.; Benson, S.M.

2008-12-01

303

Field determination of dispersivity of comingling plumes  

E-print Network

, velocity, and time and solve for dispersi- vity by trial and error. The assumption of these parameters results in the fixing of the dispersivity values calculated. In this research a closed form ana!ytical model is extended which solves the advection... OF TABLES Table 1 Ideal plume input parameters 2 Control coordinate scheme Page 23 23 3 Ideal plume data. Steady and unsteady state center- line concentrations as a function of x-distance and the associated calculated longitudinal dispersi- vities...

Kelley, Van Alan

2012-06-07

304

Magnetospheric Convection near a Drainage Plume  

Microsoft Academic Search

We report on equatorial convection associated with a plasmaspheric drainage plume using simultaneous observations from five satellites. During the early recovery phase of the July 2000 Bastille Day magnetic storm, the Extreme Ultraviolet sensor on the Magnetopause-to-Aurora Global Exploration satellite detected the plume near 16:00–17:00 magnetic local time extending outward to L ? 2.8. The plasmaspheric boundary was near L

Chin S. Lin; Huey-Ching Yeh; Bill R. Sandel; J. Goldstein; Frederick J. Rich; William J. Burke; J. C. Foster

2007-01-01

305

OPAD data analysis. [Optical Plumes Anomaly Detection  

NASA Technical Reports Server (NTRS)

Data obtained in the framework of an Optical Plume Anomaly Detection (OPAD) program intended to create a rocket engine health monitor based on spectrometric detections of anomalous atomic and molecular species in the exhaust plume are analyzed. The major results include techniques for handling data noise, methods for registration of spectra to wavelength, and a simple automatic process for estimating the metallic component of a spectrum.

Buntine, Wray L.; Kraft, Richard; Whitaker, Kevin; Cooper, Anita E.; Powers, W. T.; Wallace, Tim L.

1993-01-01

306

Scales of variability of black carbon plumes  

NASA Astrophysics Data System (ADS)

Black carbon (BC) is the major anthropogenic aerosol absorber of solar radiation, characterized by its strong absorption across a broad spectrum of visible wavelengths. Uncertainties in model simulations of BC are largely due to its high degree of spatial and temporal variability; therefore, quantifying its scales of variability is critical to determining a model's ability to accurately represent BC in the atmosphere. The purpose of this study is to quantify the scales of variability of BC plumes and to determine how these scales relate to current GCM resolutions. To analyse the plumes, we use BC measurements from the HIAPER Pole-to-Pole Observations (HIPPO) aircraft campaign, which flew multiple missions from pole-to-pole over the Pacific Ocean. During the first three missions of the HIPPO campaign, over 400 vertical profiles of BC mass measurements, extending from hundreds of metres to 14 km, were obtained using a Single Particle Soot Photometer (SP2). In this campaign, we identify a total of 102 BC plumes. We objectively analyse the plume scales using autocorrelation analysis and a plume-centric compositing technique. We found that the plumes account for a significant amount of total BC in the atmosphere and represent a large degree of the overall variability of BC. In order to make a meaningful estimation of a model's ability to resolve these plume structures, we define an approximate `effective model resolution', which takes into account the flight track geometry of the HIPPO campaign and the vertical resolution of a typical GCM. We present results decribing the scales of variability of the identified plumes and compare these scales to the `effective model resolution'. Implications of the findings and directions for future research are discussed.

Weigum, N.; Stier, P.; Schwarz, J. P.; Spackman, J. R.; Fahey, D. W.

2012-04-01

307

Plume and lithologic profiling with surface resistivity and seismic tomography.  

PubMed

Improved surface-based geophysical technologies that are commercially available provide a new level of detail that can be used to guide ground water remediation. Surface-based multielectrode resistivity methods and tomographic seismic refraction techniques were used to image to a depth of approximately 30 m below the surface at the Natural and Accelerated Bioremediation Research Field Research Center. The U.S. Department of Energy (DOE) established the research center on the DOE Oak Ridge Reservation in Oak Ridge, Tennessee, to conduct in situ field-scale studies on bioremediation of metals and radionuclides. Bioremediation studies are being conducted on the saprolite, shale bedrock, and ground water at the site that have been contaminated with nitrate, uranium, technetium, tetrachloroethylene, and other contaminants (U.S. DOE 1997). Geophysical methods were effective in imaging the high-ionic strength plume and in defining the transition zone between saprolite and bedrock zones that appears to have a significant influence on contaminant transport. The geophysical data were used to help select the location and depth of investigation for field research plots. Drilling, borehole geophysics, and ground water sampling were used to verify the surface geophysical studies. PMID:15819938

Watson, David B; Doll, William E; Gamey, T Jeffrey; Sheehan, Jacob R; Jardine, Philip M

2005-01-01

308

Vertical distribution of Pahang River plume  

NASA Astrophysics Data System (ADS)

Large rivers transported high amount of discharge towards the sea and induced the river plume formation. The contents of the plume consist of suspended solids, nutrients, pollutants and other particles. Productivity at estuary depends on the organic and nutrient contents from the river discharge. Due to many possible factors, the dispersal of the plume shows spatial variation horizontally and vertically. The monsoonal wind is a factor that effecting plume vertical profile pattern. This study determines the vertical distribution pattern of the plumeat Pahang River through field observation. Several water parameters were measured during cruises conducted at respective monsoon. Data collected includes depth, chlorophyll-a, salinity, temperature and suspended particulate matter. Depth at Pahang's offshore usually does not reached more than 15 m depth because of the shallow continental shelf at South China Sea. The plume has higher concentration at the mouth of the river which causes the area to be less saline and it decreases as the station furthers from the river. Chlorophyll-a is distributed mainly at the surface level where the area is warmer and received freshwater runoff. Suspended particulate matter shows downward distribution from the front of the estuary towards deep water column depth (10 m). Temperature pattern shows warmer surface layer with depth less than 5 m while deeper water column has lower temperature. Vertical profile pattern of Pahang River plume generally shows slight difference between each monsoon by referring to particular parameter.

Taher, T. M.; Lihan, T.; Mustapha, M. A.

2013-11-01

309

Magnetospheric Convection near a Drainage Plume  

NASA Astrophysics Data System (ADS)

We report on equatorial convection associated with a plasmaspheric drainage plume using simultaneous observations from five satellites. During the early recovery phase of the July 2000 Bastille Day magnetic storm, the Extreme Ultraviolet sensor on the Magnetopause-to-Aurora Global Exploration satellite detected the plume near 16:00-17:00 magnetic local time extending outward to L ? 2.8. The plasmaspheric boundary was near L = 2 at other local times. We mapped simultaneously measured ionospheric plasma drifts from ROCSAT-1 and three Defense Meteorological Satellite Program (DMSP) spacecraft along magnetic field lines to infer equatorial convection velocities in the inner magnetosphere. The zonal component of convection derived from ROCSAT-1 ion-drift measurements had a sharp, positive azimuthal gradient near the plume's boundaries, reversing direction from westward to eastward. The meridional profile of horizontal velocities deduced from DMSP measurements shows a large, westward-flowing subauroral polarization stream (SAPS) located outside the plasmapause. The peak velocity of the SAPS centered at a radial distance of L ? 2.8 with a full width of ˜1 RE. In the inertial frame of reference, equatorial plasmas flowed toward the plume from both its day and evening sides, suggesting a negative gradient in the equatorial azimuthal velocity that was largest near the plume's outermost boundary. These observations provide new evidence about diversion of SAPS plasma flows and distinctive azimuthal velocity patterns in the vicinity of plasmaspheric plumes.

Lin, Chin S.; Yeh, Huey-Ching; Sandel, Bill R.; Goldstein, J.; Rich, Frederick J.; Burke, William J.; Foster, J. C.

2007-05-01

310

Groundwater Contamination  

NSDL National Science Digital Library

The Groundwater Foundation's sources of ground water contamination page discusses common contaminates, how they get to ground water, sources of pollution along with cleanup and prevention practices. The site's focal point is a detailed map of contaminants as they enter the water cycle.

2008-10-13

311

Validating Watershed Delineation Algorithms in Southern Alberta, Canada.  

NASA Astrophysics Data System (ADS)

There are a number of different approaches to delineate watersheds from a digital elevation model (DEM). DEMs available in the USA are typically in integer format with a vertical resolution of 1m, which suggests the use of TOPAZ (Garbrecht and Martz, 1999). In Alberta, Canada, elevation points are available at a high resolution, allowing a generation of raster DEMs which are sub-meter vertically and 25m or less horizontally. A number of DEMs with different resolutions ranging from 100m to 5m were generated for a county in southern Alberta from elevation point data using the ANUDEM algorithm with stream burning (Hutchinson, 1988, 1989). Using different algorithms, 136 watersheds were delineated for selected points in the stream network of the study area. Recent algorithms for delineating watersheds include TARDEM (or TAUDEM) by Tarboton (1996, 2000), D8_LTD (Orlandini et.al., 2001) and the classic D8 (Baylor University, 2001). A number of watersheds were delineated in the field using a high resolution GPS. An algorithm was developed in ArcGIS to calculate differences in areas as well as the root-mean-square error (RMSE). The RMSE is an excellent measure to compare the computer delineated watersheds against each other and against the watershed boundary observed in the field.

Kienzle, S. W.; Duke, G.; Byrne, J.; Townshend, I.

2001-12-01

312

Hubble Captures Volcanic Eruption Plume From Io  

NASA Technical Reports Server (NTRS)

The Hubble Space Telescope has snapped a picture of a 400-km-high (250-mile-high) plume of gas and dust from a volcanic eruption on Io, Jupiter's large innermost moon.

Io was passing in front of Jupiter when this image was taken by the Wide Field and Planetary Camera 2 in July 1996. The plume appears as an orange patch just off the edge of Io in the eight o'clock position, against the blue background of Jupiter's clouds. Io's volcanic eruptions blasts material hundreds of kilometers into space in giant plumes of gas and dust. In this image, material must have been blown out of the volcano at more than 2,000 mph to form a plume of this size, which is the largest yet seen on Io.

Until now, these plumes have only been seen by spacecraft near Jupiter, and their detection from the Earth-orbiting Hubble Space Telescope opens up new opportunities for long-term studies of these remarkable phenomena.

The plume seen here is from Pele, one of Io's most powerful volcanos. Pele's eruptions have been seen before. In March 1979, the Voyager 1 spacecraft recorded a 300-km-high eruption cloud from Pele. But the volcano was inactive when the Voyager 2 spacecraft flew by Jupiter in July 1979. This Hubble observation is the first glimpse of a Pele eruption plume since the Voyager expeditions.

Io's volcanic plumes are much taller than those produced by terrestrial volcanos because of a combination of factors. The moon's thin atmosphere offers no resistance to the expanding volcanic gases; its weak gravity (one-sixth that of Earth) allows material to climb higher before falling; and its biggest volcanos are more powerful than most of Earth's volcanos.

This image is a contrast-enhanced composite of an ultraviolet image (2600 Angstrom wavelength), shown in blue, and a violet image (4100 Angstrom wavelength), shown in orange. The orange color probably occurs because of the absorption and/or scattering of ultraviolet light in the plume. This light from Jupiter passes through the plume and is absorbed by sulfur dioxide gas or is scattered by fine dust, or both, while violet light passes through unimpeded. Future HST observations may be able to distinguish between the gas and dust explanations.

This image and other images and data received from the Hubble Space Telescope are posted on the World Wide Web on the Space Telescope Science Institute home page at URL http://oposite.stsci.edu/pubinfo/

1997-01-01

313

Physical apparatus to demonstrate stretching and folding of contaminant/treatment solution in aquifers by extraction and injection  

NASA Astrophysics Data System (ADS)

A chief limitation to in situ groundwater remediation is the very slow velocity of groundwater. This slow velocity prevents turbulence and thereby limits mixing, especially in the case where a treatment solution is injected within the contaminated plume in order to promote degradation reactions. This study expounds on the hypothesis that injection and extraction of uncontaminated water through wells surrounding the contaminated plume can compensate for lack of natural mixing. This is done by stretching and folding the contaminant and treatment plumes around each other, vastly increasing the surface area for molecular interaction. Previous experimental work by others has shown that injection and extraction schemes can increase the perimeter length of contaminant plumes and theoretical models by our group have demonstrated that stretching and folding is an effective means to promote plume spreading. The current presentation describes an experimental apparatus constructed to study how injection and extraction schemes can be used to generate plume stretching and folding. The apparatus created to display this technique comprises two parallel plates with no flow boundary conditions providing a two-dimensional view of treatment solution surrounded by contaminated groundwater. A series of injections and extractions can manipulate these plumes in a manner that can be duplicated in the field.

Jones, M.; Mays, D. C.; Neupauer, R. M.

2012-12-01

314

Dilution and volatilization of groundwater contaminant discharges in streams.  

PubMed

An analytical solution to describe dilution and volatilization of a continuous groundwater contaminant plume into streams is developed for risk assessment. The location of groundwater plume discharge into the stream (discharge through the side versus bottom of the stream) and different distributions of the contaminant plume concentration (Gaussian, homogeneous or heterogeneous distribution) are considered. The model considering the plume discharged through the bank of the river, with a uniform concentration distribution was the most appropriate for risk assessment due to its simplicity and limited data requirements. The dilution and volatilization model is able to predict the entire concentration field, and thus the mixing zone, maximum concentration and fully mixed concentration in the stream. It can also be used to identify groundwater discharge zones from in-stream concentration measurement. The solution was successfully applied to published field data obtained in a large and a small Danish stream and provided valuable information on the risk posed by the groundwater contaminant plumes. The results provided by the dilution and volatilization model are very different to those obtained with existing point source models, with a distributed source leading to a larger mixing length and different concentration field. The dilution model can also provide recommendations for sampling locations and the size of impact zones in streams. This is of interest for regulators, for example when developing guidelines for the implementation of the European Water Framework Directive. PMID:25496819

Aisopou, Angeliki; Bjerg, Poul L; Sonne, Anne T; Balbarini, Nicola; Rosenberg, Louise; Binning, Philip J

2015-01-01

315

Dilution and volatilization of groundwater contaminant discharges in streams  

NASA Astrophysics Data System (ADS)

An analytical solution to describe dilution and volatilization of a continuous groundwater contaminant plume into streams is developed for risk assessment. The location of groundwater plume discharge into the stream (discharge through the side versus bottom of the stream) and different distributions of the contaminant plume concentration (Gaussian, homogeneous or heterogeneous distribution) are considered. The model considering the plume discharged through the bank of the river, with a uniform concentration distribution was the most appropriate for risk assessment due to its simplicity and limited data requirements. The dilution and volatilization model is able to predict the entire concentration field, and thus the mixing zone, maximum concentration and fully mixed concentration in the stream. It can also be used to identify groundwater discharge zones from in-stream concentration measurement. The solution was successfully applied to published field data obtained in a large and a small Danish stream and provided valuable information on the risk posed by the groundwater contaminant plumes. The results provided by the dilution and volatilization model are very different to those obtained with existing point source models, with a distributed source leading to a larger mixing length and different concentration field. The dilution model can also provide recommendations for sampling locations and the size of impact zones in streams. This is of interest for regulators, for example when developing guidelines for the implementation of the European Water Framework Directive.

Aisopou, Angeliki; Bjerg, Poul L.; Sonne, Anne T.; Balbarini, Nicola; Rosenberg, Louise; Binning, Philip J.

2015-01-01

316

Sewers as a source and sink of chlorinated-solvent groundwater contamination, Marine Corps Recruit Depot, Parris Island, South Carolina  

USGS Publications Warehouse

Groundwater contamination by tetrachloroethene and its dechlorination products is present in two partially intermingled plumes in the surficial aquifer near a former dry-cleaning facility at Site 45, Marine Corps Recruit Depot, Parris Island, South Carolina. The northern plume originates from the vicinity of former above-ground storage tanks. Free-phase tetrachloroethene from activities in this area entered the groundwater. The southern plume originates at a nearby, new dry-cleaning facility, but probably was the result of contamination released to the aquifer from a leaking sanitary sewer line from the former dry-cleaning facility. Discharge of dissolved groundwater contamination is primarily to leaking storm sewers below the water table. The strong influence of sanitary sewers on source distribution and of storm sewers on plume orientation and discharge at this site indicates that groundwater-contamination investigators should consider the potential influence of sewer systems at their sites. ?? 2011, National Ground Water Association.

Vroblesky, D.A.; Petkewich, M.D.; Lowery, M.A.; Landmeyer, J.E.

2011-01-01

317

MULTI-LAYER SAMPLING IN CONVENTIONAL MONITORING WELLS FOR IMPROVED ESTIMATION OF VERTICAL CONTAMINANT DISTRIBUTIONS AND MASS  

EPA Science Inventory

"Traditional" approaches to sampling groundwater and interpreting monitoring well data often provide misleading pictures of plume shape and location in the subsurface and the true extent of contamination. Groundwater samples acquired using pumps and bailers in conventional monito...

318

Columbia River Plume andColumbia River Plume and California Current Ecosystem:California Current Ecosystem  

E-print Network

Columbia River Plume andColumbia River Plume and California Current Ecosystem:California Current Ecosystem: Role in Salmon ProductivityRole in Salmon Productivity NOAA FisheriesNOAA Fisheries Northwest conditions/survivalfreshwater conditions/survival ·· The coastal pelagic ecosystem is dynamic andThe coastal

319

Delineating the Rattlesnake Springs, New Mexico Watershed Using Shallow Subsurface Geophysical Techniques and Geologic Mapping  

NASA Astrophysics Data System (ADS)

Rattlesnake Springs serves as the sole water source for Carlsbad Caverns National Park. The recent development of oil and gas leases and agricultural lands surrounding the springs has led to concern about contamination of the karst aquifer. We have used geophysical techniques, combined with geologic mapping, to delineate possible fracture systems in the gypsum and carbonate bedrock that feed the spring system. Our initial work has focused on a 700 m by 700 m region surrounding the springs. We conducted a series of ground conductivity surveys with follow-up DC resistivity surveys (Wenner array vertical electrical soundings and a pole- pole survey) to determine variations in soil grain size and moisture content. Surface geologic mapping was used to identify a series of Holocene terraces and valleys that incise the terraces. Our combined results suggest that northwest-southeast and north-south trending fractures and dissolution features control regional water flow. Relict spring valleys are found to the west of the present springs. A pole-pole survey conducted around the perimeter of the springs suggests main water flow into the springs occurs from the northwest. We plan to complete a precision gravity survey in September and October 2007 to map bedrock topography and determine its relation to structural and dissolution features. Ground penetrating radar data will be collected on the northwestern side of the springs in an attempt to better delineate structures controlling inflow into the springs.

Doser, D. I.; Langford, R. P.; Boykov, N. D.; Baker, M. R.; Kaip, G. M.

2007-12-01

320

On an automatic delineator for arterial blood pressure waveforms  

Microsoft Academic Search

Arterial blood pressure waveforms contain rich pathophysiological\\u000a information; hence receive much attention in cardiovascular health\\u000a monitoring. To assist computerized analysis, an automatic delineator\\u000a was proposed for the fiducial points of arterial blood pressure\\u000a waveforms, namely their onsets, systolic peaks and dicrotic notches.\\u000a The presented delineator characterizes arterial blood pressure\\u000a waveforms in a beat-by-beat manner. It firstly seeks the pairs of

Bing Nan Li; Ming Chui Dong; Mang I. Vai

2010-01-01

321

Insight on automated lesion delineation methods for PET data  

PubMed Central

Background Defining tumour volume for treatment response and radiotherapy planning is challenging and prone to inter- and intra-observer variability. Various automated tumour delineation methods have been proposed in the literature, each having abilities and limitations. Therefore, there is a need to provide clinicians with practical information on delineation method selection. Methods Six different automated positron emission tomography (PET) delineation methods were evaluated and compared using National Electrical Manufacturer Association image quality (NEMA IQ) phantom data and three in-house synthetic phantoms with clinically relevant lesion shapes including spheres with necrotic core and irregular shapes. The impact of different contrast ratios, emission counts, realisations and reconstruction algorithms on delineation performance was also studied using similarity index (SI) and percentage volume error (%VE) as performance measures. Results With the NEMA IQ phantom, contrast thresholding (CT) performed best on average for all sphere sizes and parameter settings (SI?=?0.83; %VE?=?5.65%?±?24.34%). Adaptive thresholding at 40% (AT40) was the next best method and required no prior parameter tuning (SI?=?0.78; %VE?=?23.22%?±?70.83%). When using SUV harmonisation filtering prior to delineation (EQ.PET), AT40 remains the best method without prior parameter tuning (SI?=?0.81; %VE?=?11.39%?±?85.28%). For necrotic core spheres and irregular shapes of the synthetic phantoms, CT remained the best performing method (SI?=?0.83; %VE?=?26.31%?±?38.26% and SI?=?0.62; %VE?=?24.52%?±?46.89%, respectively). The second best method was fuzzy locally adaptive Bayesian (FLAB) (SI?=?0.83; %VE?=?29.51%?±?81.79%) for necrotic core sphere and AT40 (SI?=?0.58; %VE?=?25.11%?±?32.41%) for irregular shapes. When using EQ.PET prior to delineation, AT40 was the best performing method without prior parameter tuning for both necrotic core (SI?=?0.83; %VE?=?27.98%?±?59.58%) and complex shapes phantoms (SI?=?0.61; %VE?=?14.83%?±?49.39%). Conclusions CT and AT40/AT50 are recommended for all lesion sizes and contrasts. Overall, considering background uptake information improves PET delineation accuracy. Applying EQ.PET prior to delineation improves accuracy and reduces coefficient of variation (CV) across different reconstructions and acquisitions. PMID:25593791

2014-01-01

322

Coronal Plumes in the Fast Solar Wind  

NASA Technical Reports Server (NTRS)

The expansion of a coronal hole filled with a discrete number of higher density coronal plumes is simulated using a time-dependent two-dimensional code. A solar wind model including an exponential coronal heating function and a flux of Alfven waves propagating both inside and outside the structures is taken as a basic state. Different plasma plume profiles are obtained by using different scale heights for the heating rates. Remote sensing and solar wind in situ observations are used to constrain the parameter range of the study. Time dependence due to plume ignition and disappearance is also discussed. Velocity differences of the order of approximately 50 km/s, such as those found in microstreams in the high-speed solar wind, may be easily explained by slightly different heat deposition profiles in different plumes. Statistical pressure balance in the fast wind data may be masked by the large variety of body and surface waves which the higher density filaments may carry, so the absence of pressure balance in the microstreams should not rule out their interpretation as the extension of coronal plumes into interplanetary space. Mixing of plume-interplume material via the Kelvin-Helmholtz instability seems to be possible within the parameter ranges of the models defined here, only at large di stances from the Sun, beyond 0.2-0.3 AU. Plasma and composition measurements in the inner heliosphere, such as those which will become available with Solar Orbiter and Solar Probe Plus, should therefore definitely be able to identify plume remnants in the solar wind.

Velli, Marco; Lionello, Roberto; Linker, Jon A.; Mikic, Zoran

2011-01-01

323

Pele Plume Deposit on Io  

NASA Technical Reports Server (NTRS)

The varied effects of Ionian volcanism can be seen in this false color infrared composite image of Io's trailing hemisphere. Low resolution color data from Galileo's first orbit (June, 1996) have been combined with a higher resolution clear filter picture taken on the third orbit (November, 1996) of the spacecraft around Jupiter.

A diffuse ring of bright red material encircles Pele, the site of an ongoing, high velocity volcanic eruption. Pele's plume is nearly invisible, except in back-lit photographs, but its deposits indicate energetic ejection of sulfurous materials out to distances more than 600 kilometers from the central vent. Another bright red deposit lies adjacent to Marduk, also a currently active ediface. High temperature hot spots have been detected at both these locations, due to the eruption of molten material in lava flows or lava lakes. Bright red deposits on Io darken and disappear within years or decades of deposition, so the presence of bright red materials marks the sites of recent volcanism.

This composite was created from data obtained by the Solid State Imaging (CCD) system aboard NASA's Galileo spacecraft. The region imaged is centered on 15 degrees South, 224 degrees West, and is almost 2400 kilometers across. The finest details that can be discerned in this picture are about 3 kilometers across. North is towards the top of the picture and the sun illuminates the surface from the west.

The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at URL http://www.jpl.nasa.gov/galileo/sepo

1997-01-01

324

Scavenging rates of dissolved manganese in a hydrothermal vent plume  

NASA Astrophysics Data System (ADS)

The biogeochemical scavenging of dissolved manganese (Mn) from hydrothermal plumes was investigated using radiotracer ( 54Mn) techniques. The measured scavenging rate constant, k 1, was lowest in the buoyant plume (<0.2 y -1), increasing to ˜2 y -1 in the non-buoyant plume at distances of 20 km from the ridge valley axis. The direct biological contribution to the dissolved Mn scavenging rate (i.e the fraction suppressed by the addition of a metabolic poison) also increased over the same distances, being minor or absent at plume depths in the proximal plume, yet the major component at distal plume stations. These and other data suggest that the capacity for scavenging dissolved Mn onto particles evolves with increasing age of the plume, suggestive of a microbial response to changing conditions within the plume. Estimated maximum scavenging rates of dissolved Mn onto particles ( RDMn = k 1 [DMn])were noted at plume depths for all stations, a function of very high dissolved Mn concentrations in the case of the buoyant plume and proximal non-buoyant plume. RDMn values, integrated over plume depths, ranged from 3.4 to 1.7 mM m -2 y -1 for the non-buoyant plume at on-axis and off-axis stations, respectively. The application of the data to the dispersal of hydrothermal constituents and to plume aging is discussed.

Cowen, James P.; Massoth, Gary J.; Feely, Richard A.

1990-10-01

325

Laboratory experiments of forced plumes in a density-stratified crossflow and implications for volcanic plumes  

NASA Astrophysics Data System (ADS)

The mass eruption rate feeding a volcanic plume is commonly estimated from its maximum height. Winds are known to affect the column dynamics causing bending and hence reducing the maximum plume height for a given mass eruption rate. However, the quantitative predictions including wind effects on mass eruption rate estimates are not well constrained. To fill this gap, we present a series of new laboratory experiments on forced plumes rising in a density-stratified crossflow. We identify three dynamical regimes corresponding to increasing effect of wind on the plume rise. The transition from one regime to another is governed by two dimensionless velocity scales defined as a function of source and environmental parameters. The results are found consistent with the conditions of historical eruptions and provide new empirical relationships to estimate mass eruption rate from plume height in windy conditions, leading to valuable tools for eruption risk assessment.

Carazzo, Guillaume; Girault, Frédéric; Aubry, Thomas; Bouquerel, Hélène; Kaminski, Edouard

2014-12-01

326

The distribution of hydrocarbons in surface and deepwater plumes during the MC252 oil spill in the Gulf of Mexico  

NASA Astrophysics Data System (ADS)

The explosion of the Deepwater Horizon oil platform on April 20, 2010 resulted in the 3rd largest global oil spill in history. Oil discharged from the Macondo 252 well (MC252) almost continuously for over 83 days, releasing an estimated 172 to 200 million gallons of oil. We investigated the chemical composition of the surface plume extending as far as 200m below the surface oil slick for comparison to a defined deep-ocean plume and tested the hypothesis that the formation of the deepwater plume could be explained, at least in part, as a function of hydrocarbon physical properties. Hydrocarbon data were acquired from the NOAA website. Results of one and two ring aromatic hydrocarbons collected in water samples between 0.3 and 1750m below surface between 5/8/2010 and 6/28/2010 were included in this analysis. Two major plumes were identified including a near-surface plume (0.3 to 200m) and a deepwater plume between approximately 1000 and 1400m below surface. In the deepwater plume, hydrocarbons were measured most frequently in a southwest direction from the MC252 well, but high levels of hydrocarbons were also occasionally observed to the north and west. Sampling bias toward the southwest, where 38% of the total samples were taken, may underestimate the distribution of hydrocarbons in deepwater to the north, northwest, and west, where 8%, 12% and 18% of the samples were taken, respectively. Different hydrocarbons were found in the deepwater plume and in the surface plume. The deepwater plume was enriched in monoaromatic hydrocarbons, including BTEX compounds. High concentrations of monoaromatic compounds were not detected in the near-surface plume. The near-surface plume was enriched in diaromatic hydrocarbons, but diaromatic compounds were also found in the deep-water plume. The vertical distribution of aromatic hydrocarbons appears to be related to their log octanol-water partition coefficient (log Kow) values. These results suggest that the distribution of compounds in the water column can be explained, at least in part, by the hydrophobicity and water solubility of the contaminants. Hydrocarbons found in the deepwater plume occurred at concentrations less than their solubility limits, suggesting that more water-soluble compounds were extracted from the rising oil plume by subsurface currents passing the oil plume in a predominantly southwest direction at a depth of between 1000 and 1400 meters. A 7.8cm/s current flowing in the SW direction from the well at 1100m was observed in June of 2010. The more hydrophobic compounds appear to have risen to the near surface with the majority of the oil released by the spill. It is hypothesized that the limited distribution of hydrocarbons in the mid-range depths between 200 and 1000 meters below surface could be due to the depletion of extractable hydrocarbons from the rising plume or the absence of a significant current at those depths. These hypotheses are being further investigated.

Spier, C. L.; Stringfellow, W. T.; Sonnenthal, E. L.; Conrad, M. E.; Hazen, T. C.

2011-12-01

327

Bulk properties of ``hot smoker'' plumes  

NASA Astrophysics Data System (ADS)

The hot buoyant fluid from a submarine vent rises as a plume, entraining fluid from the stratified ocean until a height is reached where the driving buoyant force vanishes and shortly thereafter the diluted plume fluid intrudes into the ocean interior at its equilibrium depth. While a large positive heat flux issues from the vent, the potential temperature anomaly of the horizontally spreading fluid at the equilibrium height depends on the oceanic stratification of both salinity and potential temperature, and on the salinity of the source fluid at the vent. For example, in the Atlantic Ocean, the oceanic stratification causes the spreading plume fluid to be cooler and fresher than the surrounding seawater of the same density, while in the Pacific, the spreading fluid is relatively warm. Here the well-known solution for a turbulent plume rising in a linearly stratified environment is used to obtain simple formulae for: (1) the potential temperature anomaly of the horizontally spreading fluid; (2) the heat flux associated with this injection of diluted vent water at this density level; and (3) the nondimensional solution for the evolution of tracer properties (e.g. salinity and potential temperature) in the rising plume.

McDougall, Trevor J.

1990-07-01

328

Space Shuttle Plume Simulation Effect on Aerodynamics  

NASA Technical Reports Server (NTRS)

Technology for simulating plumes in wind tunnel tests was not adequate to provide the required confidence in test data where plume induced aerodynamic effects might be significant. A broad research program was undertaken to correct the deficiency. Four tasks within the program are reported. Three of these tasks involve conducting experiments, related to three different aspects of the plume simulation problem: (1) base pressures; (2) lateral jet pressures; and (3) plume parameters. The fourth task involves collecting all of the base pressure test data generated during the program. Base pressures were measured on a classic cone ogive cylinder body as affected by the coaxial, high temperature exhaust plumes of a variety of solid propellant rockets. Valid data were obtained at supersonic freestream conditions but not at transonic. Pressure data related to lateral (separation) jets at M infinity = 4.5, for multiple clustered nozzles canted to the freestream and operating at high dynamic pressure ratios. All program goals were met although the model hardware was found to be large relative to the wind tunnel size so that operation was limited for some nozzle configurations.

Hair, L. M.

1978-01-01

329

Bayesian hierarchical approach and geophysical data sets for estimation of reactive facies over plume scales  

NASA Astrophysics Data System (ADS)

stochastic model is developed to integrate multiscale geophysical and point data sets for characterizing coupled subsurface physiochemical properties over plume-relevant scales, which is desired for parameterizing reactive transport models. We utilize the concept of reactive facies, which is based on the hypothesis that subsurface units can be identified that have distinct reactive-transport-property distributions. To estimate and spatially distribute reactive facies and their associated properties over plume-relevant scales, we need to (1) document the physiochemical controls on plume behavior and the correspondence between geochemical, hydrogeological, and geophysical measurements; and (2) integrate multisource, multiscale data sets in a consistent manner. To tackle these cross-scale challenges, we develop a hierarchical Bayesian model to jointly invert various wellbore and geophysical data sets that have different resolutions and spatial coverage. We use Markov-chain Monte-Carlo sampling methods to draw many samples from the joint posterior distribution and subsequently estimate the marginal posterior distribution of reactive-facies field and their associated reactive transport properties. Synthetic studies demonstrate that our method can successfully integrate different types of data sets. We tested the framework using the data sets collected at the uranium-contaminated Savannah River Site F-Area, including wellbore lithology, cone penetrometer testing, and crosshole and surface seismic data. Results show that the method can estimate the spatial distribution of reactive facies and their associated reactive-transport properties along a 300 m plume centerline traverse with high resolution (1.2 m by 0.305 m).

Wainwright, Haruko M.; Chen, Jinsong; Sassen, Douglas S.; Hubbard, Susan S.

2014-06-01

330

Analysis for remedial alternatives of unregulated municipal solid waste landfills leachate-contaminated groundwater  

NASA Astrophysics Data System (ADS)

A groundwater flow and solute transport model was developed using Visual Modflow for forecasting contaminant transport and assessing effects of remedial alternatives based on a case study of an unregulated landfill leachate-contaminated groundwater in eastern China. The results showed that arsenic plume was to reach the pumping well in the downstream farmland after eight years, and the longest lateral and longitudinal distance of arsenic plume was to reach 200 m and 260 m, respectively. But the area of high concentration region of arsenic plume was not to obviously increase from eight years to ten years and the plume was to spread to the downstream river and the farmland region after 20 years; while the landfill's ground was hardened, the plume was not to reach the downstream farmland region after eight years; when the pumping well was installed in the plume downstream and discharge rate was 200m3/d, the plume was to be effectively restrained; for leakage-proof barriers, it might effectively protect the groundwater of sensitive objects within an extent time range. But for the continuous point source, the plume was still to circle the leakage-proof barrier; when discharge rate of drainage ditches was 170.26 m3/d, the plume was effectively controlled; the comprehensive method combining ground-harden with drainage ditches could get the best effect in controlling contaminant diffusion, and the discharge rate was to be reduced to 111.43 m3/d. Therefore, the comprehensive remedial alternative combining ground-harden with drainage ditch will be recommended for preventing groundwater contamination when leachate leakage has happened in unregulated landfills.

An, Da; Jiang, Yonghai; Xi, Beidou; Ma, Zhifei; Yang, Yu; Yang, Queping; Li, Mingxiao; Zhang, Jinbao; Bai, Shunguo; Jiang, Lei

2013-09-01

331

Tidal networks 2. Watershed delineation and comparative network morphology  

E-print Network

of three, we quantify various tidal network properties including common power law relationships which have common power law relationships quantified for terrestrial systems to tidal systems and use these analysesTidal networks 2. Watershed delineation and comparative network morphology Andrea Rinaldo,1 Sergio

Fagherazzi, Sergio

332

The Regionalization of Africa: Delineating Africa's Subregions Using Airline Data  

ERIC Educational Resources Information Center

Current regionalizations of Africa have limitations in that they are attribute-based and regions are delineated according to national boundaries. Taking the world city network approach as starting point, it is possible to use relational data (i.e., information about the relationships between cities) rather than attribute data, and moreover, it…

Good, Pieter R.; Derudder, Ben; Witlox, Frank J.

2011-01-01

333

Quantitative comparison of delineated structure shape in radiotherapy  

NASA Astrophysics Data System (ADS)

There has been an influx of imaging and treatment technologies into cancer radiotherapy over the past fifteen years. The result is that radiation fields can now be accurately shaped to target disease delineated on pre-treatment planning scans whilst sparing critical healthy structures. Two well known problems remain causes for concern. The first is inter- and intra-observer variability in planning scan delineations, the second is the motion and deformation of a tumour and interacting adjacent organs during the course of radiotherapy which compromise the planned targeting regime. To be able to properly address these problems, and hence accurately shape the margins of error used to account for them, an intuitive and quantitative system of describing this variability must be used. This paper discusses a method of automatically creating correspondence points over similar non-polar delineation volumes, via spherical parameterisation, so that their shape variability can be analysed as a set of independent one dimensional statistical problems. The importance of 'pole' selection to initial parameterisation and hence ease of optimisation is highlighted, the use of sparse anatomical landmarks rather than spherical harmonic expansion for establishing point correspondence discussed, and point variability mapping introduced. A case study is presented to illustrate the method. A group of observers were asked to delineate a rectum on a series of time-of-treatment Cone Beam CT scans over a patient's fractionation schedule. The overall observer variability was calculated using the above method and the significance of the organ motion over time evaluated.

Price, G. J.; Moore, C. J.

2006-03-01

334

Validating Watershed Delineation Algorithms in Southern Alberta, Canada  

Microsoft Academic Search

There are a number of different approaches to delineate watersheds from a digital elevation model (DEM). DEMs available in the USA are typically in integer format with a vertical resolution of 1m, which suggests the use of TOPAZ (Garbrecht and Martz, 1999). In Alberta, Canada, elevation points are available at a high resolution, allowing a generation of raster DEMs which

S. W. Kienzle; G. Duke; J. Byrne; I. Townshend

2001-01-01

335

Automated delineation of stroke lesions using brain CT images  

PubMed Central

Computed tomographic (CT) images are widely used for the identification of abnormal brain tissue following infarct and hemorrhage in stroke. Manual lesion delineation is currently the standard approach, but is both time-consuming and operator-dependent. To address these issues, we present a method that can automatically delineate infarct and hemorrhage in stroke CT images. The key elements of this method are the accurate normalization of CT images from stroke patients into template space and the subsequent voxelwise comparison with a group of control CT images for defining areas with hypo- or hyper-intense signals. Our validation, using simulated and actual lesions, shows that our approach is effective in reconstructing lesions resulting from both infarct and hemorrhage and yields lesion maps spatially consistent with those produced manually by expert operators. A limitation is that, relative to manual delineation, there is reduced sensitivity of the automated method in regions close to the ventricles and the brain contours. However, the automated method presents a number of benefits in terms of offering significant time savings and the elimination of the inter-operator differences inherent to manual tracing approaches. These factors are relevant for the creation of large-scale lesion databases for neuropsychological research. The automated delineation of stroke lesions from CT scans may also enable longitudinal studies to quantify changes in damaged tissue in an objective and reproducible manner. PMID:24818079

Gillebert, Céline R.; Humphreys, Glyn W.; Mantini, Dante

2014-01-01

336

Interobserver Variation of Clinical Target Volume Delineation in Gastric Cancer  

SciTech Connect

Purpose: To evaluate interobserver variability in clinical target volume (CTV) delineation in gastric cancer performed with the help of a delineation guide. Patients and Methods: Ten radiotherapy centers that participate in the CRITICS Phase III trial were provided with a delineation atlas, preoperative CT scans, a postoperative planning CT scan, and clinical information for a gastric cancer case and were asked to construct a CTV and create a dosimetric plan according to departmental policy. Results: The volumes of the CTVs and planning target volumes (PTVs) differed greatly, with a mean (SD) CTV volume of 392 (176) cm{sup 3} (range, 240-821cm{sup 3}) and PTV volume of 915 (312) cm{sup 3} (range, 634-1677cm{sup 3}). The overlapping volume was 376cm{sup 3} for the CTV and 890cm{sup 3} for the PTV. The greatest differences in the CTV were seen at the cranial and caudal parts. After planning, dose coverage of the overlapping PTV volume showed less variability than the CTV. Conclusion: In this series of 10 plans, variability of the CTV in postoperative chemoradiotherapy for gastric cancer is large. Strict and clear delineation guidelines should be provided, especially in Phase III multicenter studies. Adaptations of these guidelines should be evaluated in clinical studies.

Jansen, Edwin, E-mail: epm.jansen@nki.n [Department of Radiotherapy, Netherlands Cancer Institute/Antoni van Leeuwenhoek Hospital, Amsterdam (Netherlands); Nijkamp, Jasper [Department of Radiotherapy, Netherlands Cancer Institute/Antoni van Leeuwenhoek Hospital, Amsterdam (Netherlands); Gubanski, Michael; Lind, Pehr [Department of Oncology, Karolinska Institute, Stockholm (Sweden); Verheij, Marcel [Department of Radiotherapy, Netherlands Cancer Institute/Antoni van Leeuwenhoek Hospital, Amsterdam (Netherlands)

2010-07-15

337

Position and Delineation of Chrysopetalidae and Hesionidae (Annelida, Polychaeta, Phyllodocida)  

Microsoft Academic Search

Previous studies suggest that the polychaete taxa Hesionidae and Chrysopetalidae may not represent separate groups, that Pilargidae constitute a subgroup within Hesionidae, and thatHesionidesandMicrophthalmusare highly derived hesionids. Phylogenetic systematic analyses of Phyllodocida and the subgroup Nereidiformia are presented in order to clarify the position and delineation of these taxa. The phyllodocida analysis includes 18 families representing the majority of the

Fredrik Pleijel; Thomas Dahlgren

1998-01-01

338

1. Photocopy of measured drawing (original delineated by the Royal ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

1. Photocopy of measured drawing (original delineated by the Royal Danish Academy of Fine Arts (Kunstakademiets), Copenhagen, Denmark, 1961) WEST ELEVATIONS AND PLAN OF UPPER DRONNINGENSGADE - Dronningensgade Area Study, Ninty-nine Steps, 30-31 Queen Street, Charlotte Amalie, St. Thomas, VI

339

1. Photocopy of a measured drawing (original delineated by the ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

1. Photocopy of a measured drawing (original delineated by the Royal Danish Academy of Fine Arts (Kunstakademiets), Copenhagen Denmark, 1961) ELEVATION (KING STREET), PLANS OF SECOND AND THIRD FLOORS, AND SITE PLAN - Kongensgade 53 (House), 53 King Street, Christiansted, St. Croix, VI

340

1. Photocopy of a measured drawing (original delineated by the ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

1. Photocopy of a measured drawing (original delineated by the Royal Danish Academy of Fine Arts (Kunstakademiets), Copenhagen, Denmark, 1961) PLAN OF FIRST FLOOR AND WEST ELEVATION - Kongensgade 7-8 (House), 7-8 King Street, Christiansted, St. Croix, VI

341

1. Photocopy of a measured drawing (delineated by the Kunstakademiets ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

1. Photocopy of a measured drawing (delineated by the Kunstakademiets Royal Academy of Fine Arts, Copenhagen, Denmark, 1961) CHURCH STREET (FRONT) ELEVATIONS OF KIRKEGADE 15 & 16A, and SIDE ELEVATION OF KOMPAGNIGADE 1 - Kirkegade 15 (House), 15 Church Street, Christiansted, St. Croix, VI

342

1. Photocopy of measured drawing (original delineated by the Royal ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

1. Photocopy of measured drawing (original delineated by the Royal Danish Academy of Fine Arts (Kunstakademiets), Copenhagen, Denmark, 1961) Photographer and date of photograph unknown HOSPITALSGADE (FRONT) ELEVATION - Hospitalsgade 21-22 (House), 21-22 Hospital Street, Christiansted, St. Croix, VI

343

Delineation of Preventative Landslide Buffers Along Steep Streamside Slopes in  

E-print Network

213 Delineation of Preventative Landslide Buffers Along Steep Streamside Slopes in Northern of sediment delivering to watercourses as a result of landslides generated by forest management related operations. Initial default buffers were developed through a landslide study during the planning stages

Standiford, Richard B.

344

SRNL EMERGENCY RESPONSE CAPABILITY FOR ATMOSPHERIC CONTAMINANT RELEASES  

SciTech Connect

Emergency response to an atmospheric release of chemical or radiological contamination is enhanced when plume predictions, field measurements, and real-time weather information are integrated into a geospatial framework. The Weather Information and Display (WIND) System at Savannah River National Laboratory (SRNL) utilizes such an integrated framework. The rapid availability of predictions from a suite of atmospheric transport models within this geospatial framework has proven to be of great value to decision makers during an emergency involving an atmospheric contaminant release.

Koffman, L; Chuck Hunter, C; Robert Buckley, R; Robert Addis, R

2006-07-12

345

Environmental contaminants  

USGS Publications Warehouse

Throughout the world, individuals and populations of herons are affected by environmental contaminants, leading to direct mortality, decreased reproductive success, or degradation of feeding habitat. Contaminants suspected or known to affect herons include organochlorine compounds, organophosphorus insecticides, trace elements, and petroleum (Parnell et al. 1988).General reviews on the effects of pesticides on birds (Risebrough 1986, 1991) and colonial water birds (Nisbet 1980) are presented elsewhere. The objective of this chapter is to review toxic effects of contaminants on herons. Unless otherwise noted, contaminant concentrations are presented as parts per million (ppm) on a wet weight (ww) basis.

Custer, T.W.

2000-01-01

346

In situ signatures of residual plasmaspheric plumes: Observations and simulation  

NASA Astrophysics Data System (ADS)

We compare in situ observations of the Los Alamos National Laboratory (LANL) Magnetospheric Plasma Analyzers with output of a dynamic, plasmapause test particle (PTP) simulation for the moderately disturbed interval 18-20 January 2000. In the model, weakly enhanced convection on 18 January creates a narrow drainage plume (plume A) that wraps completely around the main torus. Moderate convection on 19 January triggers significant plasmaspheric erosion, forming a second plume (B) that coexists with the narrow, wrapped, residual plume A. We fly three virtual LANL satellites through the simulation domain. The observations are globally consistent with the PTP simulation; LANL data contain several intervals of plume plasma in the model's predicted magnetic local time (MLT) sector. The modeled durations of plume sector transits are in good agreement with the LANL data. On a subglobal scale, the MLT widths and timings of the simulated plumes do not precisely agree with observations. However, several observation intervals exhibit good morphological agreement with virtual spacecraft signatures of two distinct, coexisting plumes (A and B). The fine-scale structure in the PTP model arises from the merging of residual plume A with the newer plume B. Plume merging is one theoretical means of generating fine structure in the plasmasphere: during multiple cycles of erosion and recovery, successive layers of wrapped, residual plumes can merge with newer plumes, creating layers of filamentary density structure. The model-data comparisons suggest that the plasmaspheric density distribution may preserve some memory of prior epochs of erosion and recovery.

Goldstein, J.; Thomsen, M. F.; DeJong, A.

2014-06-01

347

A new way to detect volcanic plumes  

NASA Astrophysics Data System (ADS)

of volcanic plumes, especially ash-laden ones, is important both for public health and aircraft safety. A variety of geophysical tools and satellite data are used to monitor volcanic eruptions and to predict the movement of ash. However, satellite-based methods are restricted by time of day and weather, while radars are often unavailable because of cost/portability. Here a method is proposed to detect volcanic plumes using GPS signal strength data. The strengths and limitations of the method are assessed using GPS data collected during the 2008 and 2009 eruptions of the Okmok and Mt. Redoubt volcanoes. Plume detections using this GPS technique are consistent with independently collected seismic and radar data.

Larson, Kristine M.

2013-06-01

348

Study of high altitude plume impingement  

NASA Technical Reports Server (NTRS)

The radiation intensities are determined in the base region of the space shuttle due to solid particle radiation emanating from the solid rocket motors of the shuttle. Results of an analysis of the Titan 3 and simulated solid rocket motor radiation intensities are presented. The gas particle flow fields of the Titan 3 nozzle and plume and a space shuttle solid rocket motor nozzle and plume are described. The gaseous Titan 3 flow fields are discussed utilizing the results of flow fields generated by a gaseous and two phase method-of-characteristics computer programs. A two phase computer flow field analysis program was developed. An outflow correction theory is developed which will be used to modify existing convection heat transfer methods for better heat transfer predictions on bodies immersed in rocket exhaust plumes.

Mcanally, J. V.; Smith, S. D.

1973-01-01

349

Properties of industrial dense gas plumes  

NASA Astrophysics Data System (ADS)

Hazardous gases and vapors are often discharged into the atmosphere from industrial plants during catastrophic events (e.g. Union Carbide incident in Bhopal, India). In many cases the discharged components are more dense than air and settle to the ground surface downstream from the stack exit. In the present paper, the buoyant plume model of Hoult, Fay and Forney (1969, J. Air Pollut. Control Ass. 19, 585-590.) has been altered to predict the properties of hazardous discharges. In particular, the plume impingement point, radius and concentration are predicted for typical stack exit conditions, wind speeds and temperature profiles. Asymptotic expressions for plume properties at the impingement point are also derived for a constant crosswind and neutral temperature profile. These formulae are shown to be useful for all conditions.

Shaver, E. M.; Forney, L. J.

350

Numerical and approximate solutions for plume rise  

NASA Astrophysics Data System (ADS)

Numerical and approximate analytical solutions are compared for turbulent plume rise in a crosswind. The numerical solutions were calculated using the plume rise model of Hoult, Fay and Forney (1969, J. Air Pollut. Control Ass.19, 585-590), over a wide range of pertinent parameters. Some wind shear and elevated inversion effects are included. The numerical solutions are seen to agree with the approximate solutions over a fairly wide range of the parameters. For the conditions considered in the study, wind shear effects are seen to be quite small. A limited study was made of the penetration of elevated inversions by plumes. The results indicate the adequacy of a simple criterion proposed by Briggs (1969, AEC Critical Review Series, USAEC Division of Technical Information extension, Oak Ridge, Tennesse).

Krishnamurthy, Ramesh; Gordon Hall, J.

351

Simulating Irregular Source Geometries for Ionian Plumes  

SciTech Connect

Volcanic plumes on Io respresent a complex rarefied flow into a near-vacuum in the presence of gravity. A 3D Direct Simulation Monte Carlo (DSMC) method is used to investigate the gas dynamics of such plumes, with a focus on the effects of source geometry on far-field deposition patterns. A rectangular slit and a semicircular half annulus are simulated to illustrate general principles, especially the effects of vent curvature on deposition ring structure. Then two possible models for the giant plume Pele are presented. One is a curved line source corresponding to an IR image of a particularly hot region in the volcano's caldera and the other is a large area source corresponding to the entire caldera. The former is seen to produce the features seen in observations of Pele's ring, but with an error in orientation. The latter corrects the error in orientation, but loses some structure. A hybrid simulation of 3D slit flow is also discussed.

McDoniel, W. J.; Goldstein, D. B.; Varghese, P. L.; Trafton, L. M. [University of Texas at Austin, Austin, TX 78712 (United States); Buchta, D. A.; Freund, J.; Kieffer, S. W. [University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States)

2011-05-20

352

Cargo transfer vehicle RCS propellant contamination issues  

NASA Technical Reports Server (NTRS)

The purpose of this report is to address Cargo Transfer Vehicle (CTV) RCS contamination issues and contribute to the resources necessary to optimize the vehicle and propulsion systems required in the CTV of the National Launch System (NLS) Heavy Lift Launch Vehicle (HLLV). This study reviews the thruster-induced contaminants; their transportation from the thrust chamber to the vehicle, payload, and SSF; and the mechanism by which damage is inflicted on their components. The effect of both monopropellant and bipropellant RCS rocket exhaust plumes on a spacecraft and related functional surfaces has been the subject of considerable study over the years. It is recognized that the RCS rocket produces contaminants which can significantly degrade the performance of optical windows, solar cells, thermal-protective coatings, and other external vehicle components. This is particularly true when the rocket is operating in the pulse mode. The exhaust plume impingement pressure and heat-transfer phenomena also complicate the environment to which the vehicle and its functional surfaces are exposed, but are not addressed in this study. Bipropellant contamination presented several modes of damage to incident surfaces, which can pose a long-term deleterious consequence to CTV payloads and the Space Station Freedom (SSF). Monopropellant contamination did not pose any significant long-term issues other than the possibility of aniline deposition. The use of either bipropellant and monopropellant propulsion systems can have a design impact on the CTV propulsion system with respect to maneuvering operations in the proximity of SSF.

Ballard, Richard O.

1991-01-01

353

OPTIMIZING PUMPING STRATEGIES FOR CONTAMINANT STUDIES AND REMEDIAL ACTIONS  

EPA Science Inventory

One of the more common techniques for controlling the migration of contaminant plumes is the use of pumping wells to produce desired changes in local flow rates and hydraulic gradients. When seeking to optimize an array of pumping well locations and discharge rates, it is importa...

354

Phytoremediation of Nitrate-Contaminated Groundwater by Desert Phreatophytes  

Microsoft Academic Search

Two native halophytic shrubs were evaluated for phytoremediation of a nitrate- contaminated aquifer at a former uranium mill site. The shrubs, Sarcobatus vermiculatus and Atriplex canescens, obligate and facultative phreatophytes, respectively, dominate the desert plant community. Stable isotope signatures suggested that both species are rooted into the nitrate plume, a depth averaging more than 10 meters. Aerial photography and ground

Casey McKeon; Edward P. Glenn; David Moore; W. Jody Waugh

355

BACTERIA USED TO PRECIPITATE MERCURY IN CONTAMINATED GROUNDWATER OF PAVLODAR, KAZAKHSTAN  

EPA Science Inventory

Abstract for poster presentation: A number of regions in Kazakhstan are contaminated with soluble mercury originating from industrial sources. A chlor-alkali plant that operated from 1970-1990 caused contamination of ground water near a northern suburb of Pavlodar city. The plume...

356

Dynamic Puddle Delineation and Threshold-Driven Hydrotopographic Processes  

NASA Astrophysics Data System (ADS)

DEM-based watershed delineation is a common practice and an essential step for watershed hydrologic and environmental modeling. Generally, this is a one-time work. That is, such a delineated watershed with invariant overland flow properties (e.g., flow directions, flow accumulations, and contributing areas) and a "fixed" drainage system is then used for modeling under any hydrologic conditions, including rainfall, surface ponding, soil moisture, and other conditions. This method herein is referred to as "static delineation." Additionally, it is assumed in many existing watershed models that the entire watershed contributes surface runoff to the outlet. In reality, however, a watershed surface is not a uniformly inclined plane surface and overland flow may not be sheet flow. Threshold behaviors associated with surface topography can be critical. Flow directions and accumulations for any grids may change over time, depending upon the surface depression filling-merging-spilling dynamics. Particularly, contributing areas vary, not only in relation to the watershed properties, but also the inputs of the system, such as rainfall characteristics. In the current study, we developed a new "dynamic" delineation method to precisely characterize depressions/puddles, their hydrotopographic properties and hierarchical relationships, and the threshold-controlled dynamics. Efforts also were made to deal with complex topographic conditions (e.g., flats). Testing of the new method and program was performed by using a set of topographic surfaces. In addition, an object-oriented approach was developed for image-based topographic analysis and extraction of topographic features, which were compared with the delineation results.

Chu, X.; Yang, J.; Habtezion, N.

2012-12-01

357

Cassini Radio Occultation by Enceladus Plume  

NASA Astrophysics Data System (ADS)

A fortuitous Cassini radio occultation by Enceladus plume occurs on September 15, 2006. The occultation track (the spacecraft trajectory in the plane of the sky as viewed from the Earth) has been designed to pass behind the plume (to pass above the south polar region of Enceladus) in a roughly symmetrical geometry centered on a minimum altitude above the surface of about 20 km. The minimum altitude was selected primarily to ensure probing much of the plume with good confidence given the uncertainty in the spacecraft trajectory. Three nearly-pure sinusoidal signals of 0.94, 3.6, and 13 cm-wavelength (Ka-, X-, and S-band, respectively) are simultaneously transmitted from Cassini and are monitored at two 34-m Earth receiving stations of the Deep Space Network (DSN) in Madrid, Spain (DSS-55 and DSS-65). The occultation of the visible plume is extremely fast, lasting less than about two minutes. The actual observation time extends over a much longer time interval, however, to provide a good reference baseline for potential detection of signal perturbations introduced by the tenuous neutral and ionized plume environment. Given the likely very small fraction of optical depth due to neutral particles of sizes larger than about 1 mm, detectable changes in signal intensity is perhaps unlikely. Detection of plume plasma along the radio path as perturbations in the signals frequency/phase is more likely and the magnitude will depend on the electron columnar density probed. The occultation time occurs not far from solar conjunction time (Sun-Earth-probe angle of about 33 degrees), causing phase scintillations due to the solar wind to be the primary limiting noise source. We estimate a delectability limit of about 1 to 3E16 electrons per square meter columnar density assuming about 100 seconds integration time. Potential measurement of the profile of electron columnar density along the occultation track is an exciting prospect at this time.

Kliore, A.; Armstrong, J.; Flasar, F.; French, R.; Marouf, E.; Nagy, A.; Rappaport, N.; McGhee, C.; Schinder, P.; Anabtawi, A.; Asmar, S.; Barbinis, E.; Fleischman, D.; Goltz, G.; Aguilar, R.; Rochblatt, D.

2006-12-01

358

Enceladus Plumes: A Boiling Liquid Model  

NASA Astrophysics Data System (ADS)

Following the discovery of H2O vapor and particle plumes from the tiger stripes at the south pole of Enceladus (Porco et al., 2006), observational and theoretical studies have been conducted to understand the plume mechanism (e.g., Schmidt et al., 2008; Kieffer et al., 2009; Ingersoll and Pankine, 2010). Although the “Ice Chamber Model”, which assumes that ice sublimation under the stripes causes the plumes, has successfully explained the plume mass flux (e.g., Nimmo et al., 2007; Ingersoll and Pankine, 2010), it cannot explain the high salinity in the plume (Postberg et al., 2009). Ice particles condensing from a vapor are relatively salt free, but ice particles derived from a salty liquid can have high salinity. Therefore we have investigated the “Boiling Liquid Model”, which assumes that liquid H2O under the stripes causes the plumes. With conservation of mass, momentum and energy, we built a simple atmospheric model that includes controlled boiling and gas-ice wall interaction. We first assumed that the heat radiated to space comes entirely from the heat generated by condensation of the gas onto the ice wall. We varied the width (0.1-1 m) and the height (5-4000 m) of the crack as parameters. We find that the escaping vapor flux can be relatively close to the observed value (250±100 kg/s, Hansen et al., 2006, 2008) but the radiated heat flux is only 1 GW, which is much less than the observed value (15.8 GW, Howett et al., 2011). Other models (Nimmo et al., 2007; Abramov and Spencer, 2009) also have the same difficulty accounting for the observed value. We then investigated the additional heat radiated by the particles after they come out of the crack. We built a simple model to estimate the size distributions of these condensed ice particles and their radiative properties.

Nakajima, Miki; Ingersoll, A. P.

2012-10-01

359

Delineating Contaminants and Transport Pathways Within a Coastal Watershed in Southeast Puerto Rico  

Technology Transfer Automated Retrieval System (TEKTRAN)

Coastal water quality decline due to point and non-point source pollution from terrestrial sources is a serious concern throughout the Caribbean basin and worldwide. Toxic and noxious algal blooms, declines in mangrove forests and seagrass meadows, depletion of fishery stocks, coral reef die-off, pu...

360

Plume impingement forces on inclined flat plates  

NASA Astrophysics Data System (ADS)

Plume impingement from spacecraft control thrusters on vehicles in space is simulated in wind tunnel scale experiments. Pressure and shear stress are measured on flat plates inclined to the plume axis between 0 and 90 deg. In addition to a nozzle of a 0.5N thruster, a free jet from a thin plate orifice was used, by which the flow regime from nearly free molecular flow to continuum flow was covered. Simple pressure and shear stress laws are given by which the impingement pressure and shear stress can be estimated for engineering applications.

Legge, H.

361

LAMP Observes the LCROSS Plume - Duration: 0:47.  

NASA Video Gallery

This video shows LAMPâ??s view of the LCROSS plume. The first half of the animation shows the LAMP viewport scanning across the horizon, passing through the plume, and moving on. The second half of...

362

Plume-slab interaction: The Samoa-Tonga system  

NASA Astrophysics Data System (ADS)

Mantle plume behavior near subducting plates is still poorly understood and in fact varies significantly from the classical hotspot model. We investigate using 3D laboratory models how subduction-driven flow relates to the deformation and dispersal of a nearby plume. Results show slab-driven flow severely distorts plume-driven flow, entraining and passively advecting plume material despite its thermal buoyancy. Downdip sinking of the slab initially stalls vertical plume ascent while the combination of downdip and rollback sinking motions redistribute material throughout the system. As a consequence of the subduction-induced flow, surface expressions differ significantly from traditional plume expectations. Variations in slab sinking style and plume position lead to a range in head and conduit melting signatures, as well as migrating hotspots. For the Samoa-Tonga system, model predictions are consistent with proposed entrainment of plume material around the subducting plate.

Druken, K. A.; Kincaid, C.; Griffiths, R. W.; Stegman, D. R.; Hart, S. R.

2014-07-01

363

Turbid Coastal Plume of the Elwha River, Washington  

USGS Multimedia Gallery

The turbid waters of the Elwha River and the coastal waters of the Strait de Fuca mix directly offshore of the river mouth, forming a large coastal plume.  This plume is easily identified by the cloudiness of the water (or

364

Experimental and theoretical characterization of a Hall thruster plume  

E-print Network

Despite the considerable flight heritage of the Hall thruster, the interaction of its plume with the spacecraft remains an important integration issue. Because in-flight data fully characterizing the plume in the space ...

Azziz, Yassir, 1979-

2007-01-01

365

The reactive bed plasma system for contamination control  

NASA Technical Reports Server (NTRS)

The contamination control capabilities of the Reactive Bed Plasma (RBP) system is described by delineating the results of toxic chemical composition studies, aerosol filtration work, and other testing. The RBP system has demonstrated its capabilities to decompose toxic materials and process hazardous aerosols. The post-treatment requirements for the reaction products have possible solutions. Although additional work is required to meet NASA requirements, the RBP may be able to meet contamination control problems aboard the Space Station.

Birmingham, Joseph G.; Moore, Robert R.; Perry, Tony R.

1990-01-01

366

An assessment of natural biotransformation of petroleum hydrocarbons and chlorinated solvents at an aquifer plume transect.  

PubMed

Field biogeochemical characterization and laboratory microcosm studies were performed to assess the potential for future biotransformation of trichloroethylene (TCE) and toluene in a plume containing petroleum hydrocarbons and chlorinated solvents at the former Wurtsmith Air Force Base in Oscoda, MI. In situ terminal electron accepting processes (TEAPs), contaminant composition and microbial phylogeny were studied at a plume transect 100 m downgradient of the source. The presence of reduced electron acceptors, relevant microbial communities, and elevated dissolved methane and carbon dioxide concentrations at the transect, as well as downgradient accumulation of BTEX metabolites and dechlorination products, indicated that past or current reductive dechlorination at the transect was likely driven by BTEX biodegradation in the methanogenic zone. However, TCE and toluene mineralization in sediment-groundwater microcosms without added electron acceptors did not exceed 5% during 300 days of incubation and was nearly invariant with original sediment TEAP, even following amendments of nitrogen and phosphorus. Mineralization rates were on the order of 0.0015-0.03 mumol/g day. After 8 months, microcosms showed evidence of methanogenesis, but CH4 and CO2 production arose from the degradation of contaminants other than toluene. Cis-dichloroethylene was observed in only one methanogenic microcosm after more than 500 days. It appears likely that spatially and temporally dynamic redox zonation at the plume transect will prevent future sustained reductive dehalogenation of highly chlorinated solvents, for during the course of a year, the predominant TEAP at the highly contaminated water table shifted from methanogenesis to iron- and sulfate-reduction. It is recommended that biotransformation studies combine considerations of long-term, spatially relevant changes in redox zonation with laboratory-scale studies of electron donor utilization and cometabolic substrate transformation to yield a more accurate assessment of natural bioattenuation of specific pollutants in aquifers contaminated by undefined organic waste mixtures. PMID:11351513

Skubal, K L; Barcelona, M J; Adriaens, P

2001-05-01

367

An assessment of natural biotransformation of petroleum hydrocarbons and chlorinated solvents at an aquifer plume transect  

NASA Astrophysics Data System (ADS)

Field biogeochemical characterization and laboratory microcosm studies were performed to assess the potential for future biotransformation of trichloroethylene (TCE) and toluene in a plume containing petroleum hydrocarbons and chlorinated solvents at the former Wurtsmith Air Force Base in Oscoda, MI. In situ terminal electron accepting processes (TEAPs), contaminant composition and microbial phylogeny were studied at a plume transect 100 m downgradient of the source. The presence of reduced electron acceptors, relevant microbial communities, and elevated dissolved methane and carbon dioxide concentrations at the transect, as well as downgradient accumulation of BTEX metabolites and dechlorination products, indicated that past or current reductive dechlorination at the transect was likely driven by BTEX biodegradation in the methanogenic zone. However, TCE and toluene mineralization in sediment-groundwater microcosms without added electron acceptors did not exceed 5% during 300 days of incubation and was nearly invariant with original sediment TEAP, even following amendments of nitrogen and phosphorus. Mineralization rates were on the order of 0.0015-0.03 ?mol/g day. After 8 months, microcosms showed evidence of methanogenesis, but CH 4 and CO 2 production arose from the degradation of contaminants other than toluene. Cis-dichloroethylene was observed in only one methanogenic microcosm after more than 500 days. It appears likely that spatially and temporally dynamic redox zonation at the plume transect will prevent future sustained reductive dehalogenation of highly chlorinated solvents, for during the course of a year, the predominant TEAP at the highly contaminated water table shifted from methanogenesis to iron- and sulfate-reduction. It is recommended that biotransformation studies combine considerations of long-term, spatially relevant changes in redox zonation with laboratory-scale studies of electron donor utilization and cometabolic substrate transformation to yield a more accurate assessment of natural bioattenuation of specific pollutants in aquifers contaminated by undefined organic waste mixtures.

Skubal, Karen L.; Barcelona, Michael J.; Adriaens, Peter

2001-05-01

368

Analysis of Aquifer Response, Groundwater Flow, and PlumeEvolution at Site OU 1, Former Fort Ord, California  

SciTech Connect

This report presents a continuation from Oldenburg et al. (2002) of analysis of the hydrogeology, In-Situ Permeable Flow Sensor (ISPFS) results, aquifer response, and changes in the trichloroethylene (TCE) groundwater plume at Operational Unit 1 (OU 1) adjacent to the former Fritzsche Army Airfield at the former Fort Ord Army Base, located on Monterey Bay in northern Monterey County. Fuels and solvents were burned on a portion of OU 1 called the Fire Drill Area (FDA) during airport fire suppression training between 1962 and 1985. This activity resulted in soil and groundwater contamination in the unconfined A-aquifer. In the late 1980's, soil excavation and bioremediation were successful in remediating soil contamination at the site. Shortly thereafter, a groundwater pump, treat, and recharge system commenced operation. This system has been largely successful at remediating groundwater contamination at the head of the groundwater plume. However, a trichloroethylene (TCE) groundwater plume extends approximately 3000 ft (900 m) to the northwest away from the FDA. In the analyses presented here, we augment our prior work (Oldenburg et al., 2002) with new information including treatment-system totalizer data, recent water-level and chemistry data, and data collected from new wells to discern trends in contaminant migration and groundwater flow that may be useful for ongoing remediation efforts. Some conclusions from the prior study have been modified based on these new analyses, and these are pointed out clearly in this report.

Jordan, Preston D.; Oldenburg, Curtis M.; Su, Grace W.

2005-02-24

369

Tracking Iceland Plume Motion Using Trace Element Geochemistry  

NASA Astrophysics Data System (ADS)

The Greenland-Scotland Ridge (GSR) is a hotspot track built by interaction between the Mid Atlantic Ridge (MAR) and the Iceland mantle plume. Unlike most other hotspot tracks built by ridge-plume interaction, the GSR is 2 to 3 times wider than the plume conduit in the upper mantle. (This unusual wide morphology arises because Icelandic crust changes significantly in thickness within a few million years of accretion, probably mainly by viscous flow in the hot lower crust). The upshot is that the GSR cannot be compared directly with theoretical plume tracks from hotspot reference frame models. However, it is possible to track the position of the Iceland plume conduit using the trace element geochemistry of basaltic lavas. Away from the plume conduit, plate spreading drives upwelling of mantle through the melting region. Above the plume conduit, plume-driven flow forces mantle through the lower part of the melting region faster than the plate-driven upwelling rate. The average depth of melting is therefore greater directly above the plume conduit than away from the plume conduit, and this difference in average melting depth means that melts generated directly above the plume conduit are relatively enriched in incompatible trace elements. Joint modelling of trace element compositions and crustal thickness can also be used to establish location of melting relative to the plume conduit. To date, these concepts have been used only to explain compositional variations in modern (post-glacial) Icelandic lavas; in this study we show that the same concepts can be applied to map the location of the plume conduit throughout the onshore Icelandic geological record (since the middle Miocene, c. 16 Ma). The plume track thus determined is in reasonable agreement with theoretical tracks calculated under the assumption that the Iceland Plume has remained fixed relative to other Indo-Atlantic hotspots. This result also supports the idea that episodic relocations of the onshore part of the MAR act to maintain the spreading axis above the plume conduit.

Fitton, J. G.; Walters, R. L.; Jones, S. M.

2011-12-01

370

Resistojet plume and induced environment analysis. M.S. Thesis - Case Western Reserve Univ.  

NASA Technical Reports Server (NTRS)

The source flow method developed by G.A. Simons for calculating the far field plume density produced by high thrust rocket nozzles is modified and applied to low thrust resistojet nozzles with Reynolds numbers on the order of 4000 to 7000. Simons' original method and the modified analysis are compared to mass flux measurements taken by Chirivella in a JPL vacuum tank facility. Results of the comparison show the modified analysis presented more accurately predicts the mass flux at large angles from the nozzle centerline than Simons' original method. The modified Simons analysis is then used to calculate the plume structure and two contamination parameters, number column density and back flow, for five nozzle geometries representative of Space Station resistojets.

Hoffman, David J.

1987-01-01

371

Large-eddy simulation of plume dispersion under various thermally stratified boundary layers  

NASA Astrophysics Data System (ADS)

Contaminant gas dispersion in atmospheric boundary layer is of great concern to public health. For the accurate prediction of the dispersion problem, the present study numerically investigates the behavior of plume dispersion by taking into account the atmospheric stability which is classified into three types; neutral, stable, and convective boundary layers. We first proposed an efficient method to generate spatially-developing, thermally-stratified boundary layers and examined the usefulness of our approach by comparing to wind tunnel experimental data for various thermal boundary layers. The spreads of plume in the spanwise direction are quantitatively underestimated especially at large downwind distances from the point source, owing to the underestimation of turbulence intensities for the spanwise component; however, the dependence of the spanwise spreads to atmospheric stability is well represented in a qualitative sense. It was shown that the large-eddy simulation (LES) model provides physically reasonable results.

Nakayama, H.; Takemi, T.; Nagai, H.

2014-07-01

372

FORMATION OF A DETACHED PLUME FROM A CEMENT PLANT  

EPA Science Inventory

A coordinated study of process, source emissions, and plume sampling was conducted at a coal-fired cement production plant. Both source and plume sampling consisted of particle and gas measurement and characterization. Particulate sampling of both the source and plume addressed p...

373

Chemical orientation of lobsters, homarus americanus, in turbulent odor plumes  

Microsoft Academic Search

The lobster,Homarus americanus, relies upon its lateral antennules to make initial directional choices in a turbulent odor plume. To determine whether chemical signals provide cues for source direction and distance during orientation, we studied the search patterns of the lobster orienting within a turbulent odor plume. In an odor plume, animals walked significantly more slowly and most often up the

Paul A. Moore; Nat Scholz; Jelle Atema

1991-01-01

374

Ocean and Plume Science and Management Forum January 24, 2014  

E-print Network

1 Ocean and Plume Science and Management Forum January 24, 2014 Northwest Power and Conservation of the Ocean and Plume Science and Management Forum and led a round of introductions. The October 24, 2013 from objectives 3a, 3b and 3d in the charter for the Ocean and Plume Forum. Rich then described

375

Los Alamos National Laboratory begins pumping tests on chromium plume  

E-print Network

- 1 - Los Alamos National Laboratory begins pumping tests on chromium plume May 22, 2013 Data a chromium plume in the regional aquifer. The purpose of the pumping tests is to refine understanding to remove chromium. Chromium concentrations in the plume exceed state and federal standards for groundwater

376

A study of a plume induced separation shock wave, including effects of periodic plume unsteadiness  

NASA Technical Reports Server (NTRS)

A wind tunnel investigation was conducted to study the flow field in which separation is caused by an expanding plume, with emphasis on effects associated with periodic unsteadiness in the plume. The separation shock was photographed with high speed motion pictures, from which mean shock position and excursion data were reported. Pressure fluctuations were measured beneath the separation shock. A response of the separation shock to plume periodic unsteadiness was identified, and the magnitude of a corresponding transfer function was defined. Small harmonic effects in plume response to periodic unsteadiness were noted. The stabilizing effect of a lateral surface protuberance near the separation shock wave was investigated. The protuberance configuration was a lateral circular cylinder, and various diameters, all less than the boundary layer thickness, were employed.

Doughty, J. O.

1976-01-01

377

Thruster Plume Plasma Diagnostics: A Ground Chamber Experiment for a 2-Kilowatt Arcjet  

NASA Technical Reports Server (NTRS)

Although detailed near field (0 to 3 cm) information regarding the exhaust plume of a two kilowatt arc jet is available (refs. 1 to 6), there is virtually little or no information (outside of theoretical extrapolations) available concerning the far field (2.6 to 6.1 m). Furthermore real information about the plasma at distances between (3 to 6 m) is of critical importance to high technology satellite companies in understanding the effect of arc jet plume exhausts on space based power systems. It is therefore of utmost importance that one understands the exact nature of the interaction between the arc jet plume, the spacecraft power system and the surrounding electrical plasma environment. A good first step in understanding the nature of the interactions lies in making the needed plume parameter measurements in the far field. All diagnostic measurements are performed inside a large vacuum system (12 m diameter by 18 m high) with a full scale arc jet and solar array panel in the required flight configuration geometry. Thus, necessary information regarding the plume plasma parameters in the far field is obtained. Measurements of the floating potential, the plasma potential, the electron temperature, number density, density distribution, debye length, and plasma frequency are obtained at various locations about the array (at vertical distances from the arc jet nozzle: 2.6, 2.7, 2.8, 3.2, 3.6, 4.0, 4.9, 5.0, 5.4, 5.75, and 6.14 m). Plasma diagnostic parameters are measured for both the floating and grounded configurations of the arc jet anode and array. Spectroscopic optical measurements are then acquired in close proximity to the nozzle, and contamination measurements are made in the vicinity of the array utilizing a mass spectrometer and two Quartz Crystal Microbalances (QCM's).

Galofaro, Joel T.; Vayner, Boris V.; Hillard, G. Barry; Chornak, Michael T.

2005-01-01

378

Extraterrestrial influences on mantle plume activity  

Microsoft Academic Search

We use time series analysis to compare the impact histories of the Earth and Moon with the record of mantle plume activity. We use events with errors in their ages of ?150 Ma. The terrestrial and lunar impact records, when smoothed at a 45-Ma interval, correlate at a 97% confidence level. This high confidence level suggests that we have an

Dallas H Abbott; Ann E Isley

2002-01-01

379

Preliminary plume characteristics of an arcjet thruster  

NASA Technical Reports Server (NTRS)

An experimental investigation of a low power arcjet plume was conducted using emission spectroscopy. A laboratory model arcjet incorporating a segmented anode was run on simulated hydrazine at a flow rate of 5 x 10(exp -5) kg/s. The complete visible spectrum measured in the exit plane of the arcjet showed the presence of N2, N2(+), NH, and H. Radial intensity profiles for the H alpha, H sub beta, and the NH A(sup 3)Pi yields X(sup 3)Sigma(0,0) transitions at four different axial locations were measured. These line of sight intensity measurements, spaced 0.05 mm apart, were deconvoluted to give the radial intensity distribution using an inverse Abel transformation. The ratio between the intensities from the H sub alpha and H sub beta transitions indicated a non-Boltzmann energy distribution between excited states in the plume. Axial intensity profiles taken on center line indicated the decay rate of excited states in the plume. An electron number density of 2 x 10(exp 13)/cu cm at the exit plane was determined based on Stark broadening of the H sub beta line. Rotational temperatures of 750 K, 1750 K, and 2500 K were determined for N2, N2(+), and NH respectively. The results demonstrate that the location of the current attachment on the anode has a measurable effect on the electronically excited species in the plume and that dissociation is the dominant frozen flow loss mechanism in low power arcjets.

Manzella, David H.; Curran, Francis M.; Myers, Roger M.; Zube, Dieter M.

1990-01-01

380

The water vapor plumes of Enceladus  

NASA Astrophysics Data System (ADS)

The Cassini E3, E5, and E7 encounters with Enceladus probed the south polar plumes, where the Ion and Neutral Mass Spectrometer (INMS) measured neutral H2O molecular densities up to ˜109 cm-3. We have constructed a physical model for the expected water density in the plumes, based on supersonic radial outflow from one or more of the surface vents. We apply this model to possible surface sources of water vapor associated with the multiple jets observed in the visible dust plumes. Our model predictions fit well with the INMS measurements of neutral H2O density along the E3, E5, and E7 trajectories. The fit is optimized by values of outflow velocity in the range ˜550-750 m/s and values of total source rate in the range ˜1.5 - 3.5 × 1028 H2O molecules/s. The model can be extended to incorporate the jet features within the plume observed during the E7 encounter.

Dong, Y.; Hill, T. W.; Teolis, B. D.; Magee, B. A.; Waite, J. H.

2011-10-01

381

STS-98 Emits Plume of Smoke  

NASA Technical Reports Server (NTRS)

This awesome image depicts the full moon, sunset launch of the Space Shuttle Orbiter Atlantis STS-98 mission on February 7, 2001 at 6:13 p.m. eastern time. The large white plume is the pillar of smoke and stream left behind by the solid rocket boosters. The very bright dot that exists above the plume is the flame still visible at the base of the rocket boosters. The top of the plume is being directly illuminated by sunlight whereas the bottom portion lies within the Earth's shadow. The bright orb in the lower right-hand corner of the image is the full sunlit face of the moon which has already risen above the eastern horizon. The dark cone-shaped feature extending downward towards the moon is the smoke plume shadow, known as the Bugeron Effect (common during sunrise and sunset launches). The Earth, Moon, and Sun were naturally in alignment causing the shadow to appear to end at the moon. (Photo courtesy Patrick McCracken, NASA Headquarters)

2001-01-01

382

Lithological structure of the Galápagos Plume  

NASA Astrophysics Data System (ADS)

We have measured Ni, Ca, and Mn in olivine phenocrysts from volcanoes in the Galápagos Archipelago to infer the mantle source lithologies. Results show that peridotite is the dominant source lithology for Fernandina, Floreana, Genovesa, Wolf Island, and Darwin Island. These volcanoes largely characterize the PLUME, WD, FLO, and DUM Nd, Sr, and Pb isotopic endmembers of Harpp and White (2001). Volcan Wolf, Alcedo, Marchena, and Cerro Azul, also produced from the melting of peridotite sources, have isotopic compositions that can be defined by mixing of the four isotopic endmembers. Our analysis suggests that peridotite was present in the sources of the volcanoes covered in this study and therefore is the dominant source lithology of the Galápagos plume. Pyroxenite melting is generally focused in two isotopically distinct domains: Roca Redonda, Volcan Ecuador, and Sierra Negra in the enriched western part of the archipelago and Santiago, Santa Cruz, and Santa Fe in the depleted east. One implication of this finding is that the Western and Eastern Pyroxenite Domains represent two separate bodies of recycled crust within the Galápagos mantle plume. Furthermore, both isotopically enriched and depleted domains of the archipelago were generated from mixtures of peridotite and pyroxenite. This suggests that there is no relationship between the source lithology of the Galápagos plume and its isotopic characteristics. The identification of peridotite-source melting in volcanoes with isotopic characteristics that have been attributed to recycled crust points to the importance of mixing in OIB genesis, consistent with studies in the Canary Islands.

Vidito, Christopher; Herzberg, Claude; Gazel, Esteban; Geist, Dennis; Harpp, Karen

2013-10-01

383

Halema'uma'u Vent Gas Plume  

USGS Multimedia Gallery

Over the past several days, the lava surface within the vent in Halema'uma'u has occasionally, and temporarily, reached to within about 115 m (375 ft) below the floor of Halema'uma'u Crater, as seen in this photo. During these high-lava stands, the gas plume is generally fairly wispy, providing the ...

384

Modeling of Plume Dynamics in Laser Ablation  

Microsoft Academic Search

The aim of this study is to find thermal conditions for the formation of carbon annotates in a laser furnace. The proposed model includes a multi-species formulation for concentration of chemical components combined with the compressible Euler equations. An axisymmetric unsteady computational gas dynamic model of plume expansion into ambiance has been developed. In the present work, the system of

Diomar Lobao; Alex Povitsky

2003-01-01

385

PLUME DEFINITION IN REGIONS OF STRONG BENDING  

EPA Science Inventory

In recent years most of the emphasis in plume modeling has been directed at improving the entrainment equations while the non-entrainment equations (momentum, energy, state, etc.) have been thought to be firmly established. t is shown that serious deficiencies remain in the non-e...

386

4 -Coastal Ocean Processes Plume Survey  

E-print Network

winds sustained at 15 knots. The quantity of measurements we were able to make in the heavily fished transformations as well as the broader quasi-syn- optic view. Studies will also compare between re- gions north of observed variability will be provided by an array of moored sensors deployed in the plume as well

Pierce, Stephen

387

Columbia River Plume 2006 OSU Ocean Mixing  

E-print Network

turbulence. Our measurements of chlorophyll, optical backscatter, acoustic backscatter, density, velocity;Columbia River Plume 2006 OSU Ocean Mixing Nash, Kilcher, Moum et al. Instrument Sensor Measurement Airfoil pressure CTD, 3 cm salinity, density; 1 cm temperature Seapoint Sensors 880 nm optical backscatter

Hickey, Barbara

388

Penetration of mantle plumes through depleted lithosphere  

Microsoft Academic Search

Laboratory experiments and numerical calculations are used to study how a laminar thermal plume deforms and penetrates a buoyant and viscous layer, which serves as an analog for continental lithosphere. The viscosity contrast between the two liquids and the buoyancy ratio B (the ratio between the intrinsic chemical density contrast and the thermal density contrast due to temperature differences) are

D. Jurine; C. Jaupart; G. Brandeis; P. J. Tackley

2005-01-01

389

Role of back diffusion and biodegradation reactions in sustaining an MTBE/TBA plume in alluvial media  

USGS Publications Warehouse

A methyl tert-butyl ether (MTBE) / tert-butyl alcohol (TBA) plume originating from a gasoline spill in late 1994 at Vandenberg Air Force Base (VAFB) persisted for over 15 years within 200 feet of the original spill source. The plume persisted until 2010 despite excavation of the tanks and piping within months after the spill and excavations of additional contaminated sediments from the source area in 2007 and 2008. The probable history of MTBE concentrations along the plume centerline at its source was estimated using a wide variety of available information, including published details about the original spill, excavations and monitoring by VAFB consultants, and our own research data. Two-dimensional reactive transport simulations of MTBE along the plume centerline were conducted for a 20-year period following the spill. These analyses suggest that MTBE diffused from the thin anaerobic aquifer into the adjacent anaerobic silts and transformed to TBA in both aquifer and silt layers. The model reproduces the observation that after 2004 TBA was the dominant solute, diffusing back out of the silts into the aquifer and sustaining plume concentrations much longer than would have been the case in the absence of such diffusive exchange. Simulations also suggest that aerobic degradation of MTBE or TBA at the water table in the overlying silt layer significantly affected concentrations of MTBE and TBA by limiting the chemical mass available for back diffusion to the aquifer.

Rasa, Ehsan; Chapman, Steven W.; Bekins, Barbara A.; Fogg, Graham E.; Scow, Kate M.; Mackay, Douglas M.

2011-01-01

390

Role of back diffusion and biodegradation reactions in sustaining an MTBE/TBA plume in alluvial media  

PubMed Central

A methyl tert-butyl ether (MTBE) / tert-butyl alcohol (TBA) plume originating from a gasoline spill in late 1994 at Vandenberg Air Force Base (VAFB) persisted for over 15 years within 200 feet of the original spill source. The plume persisted until 2010 despite excavation of the tanks and piping within months after the spill and excavations of additional contaminated sediments from the source area in 2007 and 2008. The probable history of MTBE concentrations along the plume centerline at its source was estimated using a wide variety of available information, including published details about the original spill, excavations and monitoring by VAFB consultants, and our own research data. Two-dimensional reactive transport simulations of MTBE along the plume centerline were conducted for a 20-year period following the spill. These analyses suggest that MTBE diffused from the thin anaerobic aquifer into the adjacent anaerobic silts and transformed to TBA in both aquifer and silt layers. The model reproduces the observation that after 2004 TBA was the dominant solute, diffusing back out of the silts into the aquifer and sustaining plume concentrations much longer than would have been the case in the absence of such diffusive exchange. Simulations also suggest that aerobic degradation of MTBE or TBA at the water table in the overlying silt layer significantly affected concentrations of MTBE and TBA by limiting the chemical mass available for back diffusion to the aquifer. PMID:22115089

Rasa, Ehsan; Chapman, Steven W.; Bekins, Barbara A.; Fogg, Graham E.; Scow, Kate M.; Mackay, Douglas M.

2012-01-01

391

Representative Atmospheric Plume Development for Elevated Releases  

SciTech Connect

An atmospheric explosion of a low-yield nuclear device will produce a large number of radioactive isotopes, some of which can be measured with airborne detection systems. However, properly equipped aircraft may not arrive in the region where an explosion occurred for a number of hours after the event. Atmospheric conditions will have caused the radioactive plume to move and diffuse before the aircraft arrives. The science behind predicting atmospheric plume movement has advanced enough that the location of the maximum concentrations in the plume can be determined reasonably accurately in real time, or near real time. Given the assumption that an aircraft can follow a plume, this study addresses the amount of atmospheric dilution expected to occur in a representative plume as a function of time past the release event. The approach models atmospheric transport of hypothetical releases from a single location for every day in a year using the publically available HYSPLIT code. The effective dilution factors for the point of maximum concentration in an elevated plume based on a release of a non-decaying, non-depositing tracer can vary by orders of magnitude depending on the day of the release, even for the same number of hours after the release event. However, the median of the dilution factors based on releases for 365 consecutive days at one site follows a power law relationship in time, as shown in Figure S-1. The relationship is good enough to provide a general rule of thumb for estimating typical future dilution factors in a plume starting at the same point. However, the coefficients of the power law function may vary for different release point locations. Radioactive decay causes the effective dilution factors to decrease more quickly with the time past the release event than the dilution factors based on a non-decaying tracer. An analytical expression for the dilution factors of isotopes with different half-lives can be developed given the power law expression for the non-decaying tracer. If the power-law equation for the median dilution factor, Df, based on a non-decaying tracer has the general form Df=a?×t?^(-b) for time t after the release event, then the equation has the form Df=e^(-?t)×a×t^(-b) for a radioactive isotope, where ? is the decay constant for the isotope.

Eslinger, Paul W.; Lowrey, Justin D.; McIntyre, Justin I.; Miley, Harry S.; Prichard, Andrew W.

2014-03-03

392

The thin hot plume beneath Iceland  

USGS Publications Warehouse

We present the results of a seismological investigation of the frequency-dependent amplitude variations across Iceland using data from the HOTSPOT array currently deployed there. The array is composed of 30 broad-band PASSCAL instruments. We use the parameter t(*), defined in the usual manner from spectral ratios (Halderman and Davis 1991), to compare observed S-wave amplitude variations with those predicted due to both anelastic attenuation and diffraction effects. Four teleseismic events at a range of azimuths are used to measure t(*). A 2-D vertical cylindrical plume model with a Gaussian-shaped velocity anomaly is used to model the variations. That part of t(*) caused by attenuation was estimated by tracing a ray through IASP91, then superimposing our plume model velocity anomaly and calculating the path integral of 1/vQ. That part of t(*) caused by diffraction was estimated using a 2-D finite difference code to generate synthetic seismograms. The same spectral ratio technique used for the data was then used to extract a predicted t(*). The t(*) variations caused by anelastic attenuation are unable to account for the variations we observe, but those caused by diffraction do. We calculate the t(*) variations caused by diffraction for different plume models and obtain our best-fit plume, which exhibits good agreement between the observed and measured t(*). The best-fit plume model has a maximum S-velocity anomaly of - 12 per cent and falls to 1/e of its maximum at 100 km from the plume centre. This is narrower than previous estimates from seismic tomography, which are broadened and damped by the methods of tomography. This velocity model would suggest greater ray theoretical traveltime delays than observed. However, we find that for such a plume, wave-front healing effects at frequencies of 0.03-0.175 Hz (the frequency range used to pick S-wave arrivals) causes a 40 per cent reduction in traveltime delay, reducing the ray theoretical delay to that observed.

Allen, R.M.; Nolet, G.; Morgan, W.J.; Vogfjord, K.; Bergsson, B.H.; Erlendsson, P.; Foulger, G.R.; Jakobsdottir, S.; Julian, B.R.; Pritchard, M.; Ragnarsson, S.; Stefansson, R.

1999-01-01

393

Fallout plume of submerged oil from Deepwater Horizon  

PubMed Central

The sinking of the Deepwater Horizon in the Gulf of Mexico led to uncontrolled emission of oil to the ocean, with an official government estimate of ?5.0 million barrels released. Among the pressing uncertainties surrounding this event is the fate of ?2 million barrels of submerged oil thought to have been trapped in deep-ocean intrusion layers at depths of ?1,000–1,300 m. Here we use chemical distributions of hydrocarbons in >3,000 sediment samples from 534 locations to describe a footprint of oil deposited on the deep-ocean floor. Using a recalcitrant biomarker of crude oil, 17?(H),21?(H)-hopane (hopane), we have identified a 3,200-km2 region around the Macondo Well contaminated by ?1.8 ± 1.0 × 106 g of excess hopane. Based on spatial, chemical, oceanographic, and mass balance considerations, we calculate that this contamination represents 4–31% of the oil sequestered in the deep ocean. The pattern of contamination points to deep-ocean intrusion layers as the source and is most consistent with dual modes of deposition: a “bathtub ring” formed from an oil-rich layer of water impinging laterally upon the continental slope (at a depth of ?900–1,300 m) and a higher-flux “fallout plume” where suspended oil particles sank to underlying sediment (at a depth of ?1,300–1,700 m). We also suggest that a significant quantity of oil was deposited on the ocean floor outside this area but so far has evaded detection because of its heterogeneous spatial distribution. PMID:25349409

Valentine, David L.; Fisher, G. Burch; Bagby, Sarah C.; Nelson, Robert K.; Reddy, Christopher M.; Sylva, Sean P.; Woo, Mary A.

2014-01-01

394

Fallout plume of submerged oil from Deepwater Horizon.  

PubMed

The sinking of the Deepwater Horizon in the Gulf of Mexico led to uncontrolled emission of oil to the ocean, with an official government estimate of ? 5.0 million barrels released. Among the pressing uncertainties surrounding this event is the fate of ? 2 million barrels of submerged oil thought to have been trapped in deep-ocean intrusion layers at depths of ? 1,000-1,300 m. Here we use chemical distributions of hydrocarbons in >3,000 sediment samples from 534 locations to describe a footprint of oil deposited on the deep-ocean floor. Using a recalcitrant biomarker of crude oil, 17?(H),21?(H)-hopane (hopane), we have identified a 3,200-km(2) region around the Macondo Well contaminated by ? 1.8 ± 1.0 × 10(6) g of excess hopane. Based on spatial, chemical, oceanographic, and mass balance considerations, we calculate that this contamination represents 4-31% of the oil sequestered in the deep ocean. The pattern of contamination points to deep-ocean intrusion layers as the source and is most consistent with dual modes of deposition: a "bathtub ring" formed from an oil-rich layer of water impinging laterally upon the continental slope (at a depth of ? 900-1,300 m) and a higher-flux "fallout plume" where suspended oil particles sank to underlying sediment (at a depth of ? 1,300-1,700 m). We also suggest that a significant quantity of oil was deposited on the ocean floor outside this area but so far has evaded detection because of its heterogeneous spatial distribution. PMID:25349409

Valentine, David L; Fisher, G Burch; Bagby, Sarah C; Nelson, Robert K; Reddy, Christopher M; Sylva, Sean P; Woo, Mary A

2014-11-11

395

Defining neuroscience nursing practice: the 2001 role delineation study.  

PubMed

Studies that provided a blueprint for the Certified Neuroscience Registered Nurse (CNRN) examination were conducted in 1987, 1992, and 1997. In 2000, the American Board of Neuroscience Nursing (ABNN) formed a task force to re-examine the previous role delineation survey, obtain information to define current neuroscience nursing practice, and provide content validity for future CNRN examinations. Previous role delineation studies conducted by ABNN and a review of the literature provided the background for the study. The theoretical framework was the Nursing Intervention Classification (NIC) taxonomy and the methodology was a survey design. Computer Adaptive Technologies, Inc. (CAT), assisted the task force with survey development and data analysis. The survey, a three-part questionnaire, was mailed to 1,505 CNRNs and returned by 453 participants. PMID:12789716

Blissitt, Patricia A; Roberts, Stephen; Hinkle, Janice L; Kopp, Elaine M

2003-02-01

396

Population delineation of polar bears using satellite collar data  

USGS Publications Warehouse

To produce reliable estimates of the size or vital rates of a given population, it is important that the boundaries of the population under study are clearly defined. This is particularly critical for large, migratory animals where levels of sustainable harvest are based on these estimates, and where small errors may have serious long-term consequences for the population. Once populations are delineated, rates of exchange between adjacent populations can be determined and accounted/corrected for when calculating abundance (e.g., based on mark-recapture data). Using satellite radio-collar locations for polar bears in the western Canadian Arctic, we illustrate one approach to delineating wildlife populations that integrates cluster analysis methods for determining group membership with home range plotting procedures to define spatial utilization. This approach is flexible with respect to the specific procedures used and provides an objective and quantitative basis for defining population boundaries.

Bethke, R.; Taylor, M.; Amstrup, S.; Messler, F.

1996-01-01

397

A Comparative Review of North American Tundra Delineations  

NASA Technical Reports Server (NTRS)

Recent profound changes have been observed in the Arctic environment, including record low sea ice extents and high latitude greening. Studying the Arctic and how it is changing is an important element of climate change science. The Tundra, an ecoregion of the Arctic, is directly related to climate change due to its effects on the snow ice feedback mechanism and greenhouse gas cycling. Like all ecoregions, the Tundra border is shifting, yet studies and policies require clear delineation of boundaries. There are many options for ecoregion classification systems, as well as resources for creating custom maps. To help decision makers identify the best classification system possible, we present a review of North American Tundra ecoregion delineations and further explore the methodologies, purposes, limitations, and physical properties of five common ecoregion classification systems. We quantitatively compare the corresponding maps by area using a geographic information system.

Silver, Kirk C.; Carroll, Mark

2013-01-01

398

EVALUATION OF NATURAL AND IN-SITU REMEDIATION TECHNOLOGIES FOR A COAL-RELATED METALS PLUME  

SciTech Connect

Metals contamination exceeding drinking water standards (MCLs) is associated with acidic leachate generated from a coal pile runoff basin at the Savannah River Site (SRS) in Aiken, South Carolina. The metals plume extends over 100 acres with its' distal boundary about onehalf mile from the Savannah River. Based on the large plume extent and high dissolved iron and aluminum concentrations, conventional treatment technologies are likely to be ineffective and cost prohibitive. In-situ bioremediation using existing groundwater microbes is being evaluated as a promising alternative technology for effective treatment, along with consideration of natural attenuation of the lower concentration portions of the plume to meet remedial goals. Treatment of the high concentration portion of the groundwater plume by sulfate-reducing bacteria (SRB) is being evaluated through laboratory microcosm testing and a field-scale demonstration. Organic substrates are added to promote SRB growth. These bacteria use dissolved sulfate as an electron acceptor and ultimately precipitate dissolved metals as metal sulfides. Laboratory microcosm testing indicate SRB are present in groundwater despite low pH conditions, and that their growth can be stimulated by soybean oil and sodium lactate. The field demonstration consists of substrate injection into a 30-foot deep by 240-foot long permeable trench. Microbial activity is demonstrated by an increase in pH from 3 to 6 within the trench. Downgradient monitoring will be used to evaluate the effectiveness of SRB in reducing metal concentrations. Natural attenuation (NA) is being evaluated for the low concentration portion of the plume. A decrease in metal mobility can occur through a variety of abiotically and/or biotically mediated mechanisms. Quantification of these mechanisms is necessary to more accurately predict contaminant attenuation using groundwater transport models that have historically relied on simplified conservative assumptions. Result s from matched soil/porewater samples indicate higher soil/water partition coefficients (Kds) with increasing distance from the source. In addition, site-specific metals availability is being assessed using sequential extraction techniques, which more accurately represent environmental conditions as compared to default EPA extraction methods. Due to elevated sulfate levels in the plume, SRB are most likely to be the dominant biotic contributor to NA processes.

Ross, Jeffrey A.; Bayer, Cassandra L.; Socha, Ronald P.; Sochor,Cynthia S.; Fliermans, Carl B.; McKinsey, Pamela C.; Millings, Margaret R.; Phifer, Mark A.; Powell, Kimberly R.; Serkiz, Steven M.; Sappington, Frank C.; Turick, Charles E.

2003-02-27

399

Characterization of DNAPL Source Zone Architecture and Prediction of Associated Plume Response: Progress and Perspectives  

NASA Astrophysics Data System (ADS)

It is now widely recognized that the distribution of contaminant mass will control both the evolution of aqueous phase plumes and the effectiveness of many source zone remediation technologies at sites contaminated by dense nonaqueous phase liquids (DNAPLs). Advances in the management of sites containing DNAPL source zones, however, are currently hampered by the difficulty associated with characterizing subsurface DNAPL 'architecture'. This presentation provides an overview of recent research, integrating experimental and mathematical modeling studies, designed to improve our ability to characterize DNAPL distributions and predict associated plume response. Here emphasis is placed on estimation of the most information-rich DNAPL architecture metrics, through a combination of localized in situ tests and more readily available plume transect concentration observations. Estimated metrics will then serve as inputs to an upscaled screening model for prediction of long term plume response. Machine learning techniques were developed and refined to identify a variety of source zone metrics and associated confidence intervals through the processing of down gradient concentration data. Estimated metrics include the volumes and volume percentages of DNAPL in pools and ganglia, as well as their ratio (pool fraction). Multiphase flow and transport simulations provided training data for model development and assessment that are representative of field-scale DNAPL source zones and their evolving plumes. Here, a variety of release and site heterogeneity (sequential Gaussian permeability) conditions were investigated. Push-pull tracer tests were also explored as a means to provide localized in situ observations to refine these metric estimates. Here, two-dimensional aquifer cell experiments and mathematical modeling were used to quantify upscaled interphase mass transfer rates and the interplay between injection and extraction rates, local source zone architecture, and tracer concentration measurements. Finally, two-dimensional aquifer cell experiments for representative DNAPL release events were performed to explore the link between source zone metrics and plume development, and to demonstrate the utility of the developed estimation tools and upscaled models. Research results reveal that, for the subsurface scenarios examined, many metrics can be estimated at greater than 80% accuracy from concentration transect measurements. Partitioning tracer investigations demonstrate that push-pull tracer data cannot be accurately modeled using local equilibrium assumptions and that fitted upscaled mass transfer coefficients exhibit a strong dependence on DNAPL mass distribution, a dependence that can be exploited for local metric identification. Aquifer cell experiments demonstrate that upscaled screening model predictions can capture the multi-stage behavior of single component NAPL fluxes from source zone architectures initially characterized as ganglia-dominated, and that transitions from ganglia- to pool-dominated architecture can be predicted using source zone metrics such as pool fraction.

Abriola, L. M.; Pennell, K. D.; Ramsburg, C. A.; Miller, E. L.; Christ, J.; Capiro, N. L.; Mendoza-Sanchez, I.; Boroumand, A.; Ervin, R. E.; Walker, D. I.; Zhang, H.

2012-12-01

400

Design, Fabrication, and Testing of Emissive Probes to Determine the Plasma Potential of the Plumes of Various Electric Thrusters  

NASA Technical Reports Server (NTRS)

A significant problem in the use of electric thrusters in spacecraft is the formation of low-energy ions in the thruster plume. Low-energy ions are formed in the plume via random collisions between high-velocity ions ejected from the thruster and slow-moving neutral atoms of propellant effusing from the engine. The sputtering of spacecraft materials due to interactions with low-energy ions may result in erosion or contamination of the spacecraft. The trajectory of these ions is determined primarily by the plasma potential of the plume. Thus, accurate characterization of the plasma potential is essential to predicting low-energy ion contamination. Emissive probes were utilized to determine the plasma potential. When the ion and electron currents to the probe are balanced, the potential of such probes float to the plasma potential. Two emissive probes were fabricated; one utilizing a DC power supply, another utilizing a rectified AC power source. Labview programs were written to coordinate and automate probe motion in the thruster plume. Employing handshaking interaction, these motion programs were synchronized to various data acquisition programs to ensure precision and accuracy of the measurements. Comparing these experimental values to values from theoretical models will allow for a more accurate prediction of low-energy ion interaction.

Chen, Erinna M.

2005-01-01

401

A hierarchy of dynamic plume models incorporating uncertainty: Volume 3, Second-Order Closure Integrated Model Plume (SCIMP): Final report  

Microsoft Academic Search

The Second Order Closure Integrated Model Plume (SCIMP) is the lowest resolution member of a hierarchy of models. It simulates the expected value of plume concentration downwind of a fossil-fueled powerplant stack, along with an estimate of the variation around this value. To represent the turbulent atmosphere surrounding the plume compatibly with available meteorological data, a second order closure sub-model

R. I. Sykes; W. S. Lewellen; S. F. Parker; D. S. Henn

1989-01-01

402

Delineation of a clinical syndrome caused by mosaic trisomy 15  

SciTech Connect

We report on a boy with mosaic trisomy 15. The clinical manifestations are compared with those of the few cases reported up to now. A clinical syndrome is delineated consisting of a characteristic shape of the nose and other minor craniofacial anomalies, as well as typical deformities of the hands and feet. Different degrees of mosaicism may explain the more or less severe manifestations in individual patients. 10 refs., 4 figs., 1 tab.

Buehler, E.M.; Bienz, G.; Straumann, E.; Bosceh, N. [Univ. Children`s Hospital, Basel (Switzerland)

1996-03-15

403

Methods for Data-based Delineation of Spatial Regions  

SciTech Connect

In data analysis, it is often useful to delineate or segregate areas of interest from the general population of data in order to concentrate further analysis efforts on smaller areas. Three methods are presented here for automatically generating polygons around spatial data of interest. Each method addresses a distinct data type. These methods were developed for and implemented in the sample planning tool called Visual Sample Plan (VSP). Method A is used to delineate areas of elevated values in a rectangular grid of data (raster). The data used for this method are spatially related. Although VSP uses data from a kriging process for this method, it will work for any type of data that is spatially coherent and appears on a regular grid. Method B is used to surround areas of interest characterized by individual data points that are congregated within a certain distance of each other. Areas where data are “clumped” together spatially will be delineated. Method C is used to recreate the original boundary in a raster of data that separated data values from non-values. This is useful when a rectangular raster of data contains non-values (missing data) that indicate they were outside of some original boundary. If the original boundary is not delivered with the raster, this method will approximate the original boundary.

Wilson, John E.

2012-10-01

404

Tools to analyse and display variations in anatomical delineation.  

PubMed

Variations in anatomical delineation, principally due to a combination of inter-observer contributions and image-specificity, remain one of the most significant impediments to geometrically-accurate radiotherapy. Quantification of spatial variability of the delineated contours comprising a structure can be made with a variety of metrics, and the availability of software tools to apply such metrics to data collected during inter-observer or repeat-imaging studies would allow their validation. A suite of such tools have been developed which use an Extensible Markup Language format for the exchange of delineated 3D structures with radiotherapy planning or review systems. These tools provide basic operations for manipulating and operating on individual structures and related structure sets, and for deriving statistics on spatial variations of contours that can be mapped onto the surface of a reference structure. Use of these tools on a sample dataset is demonstrated together with import and display of results in the SWAN treatment plan review system. PMID:22581501

Ebert, Martin A; McDermott, L N; Haworth, A; van der Wath, E; Hooton, B

2012-06-01