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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

Detailed Vertical and Lateral Delineation of Redox Zones in Contaminant Plumes Using Redox-Sensitive Tapes (RST)  

NASA Astrophysics Data System (ADS)

Innovative redox-sensitive tapes (RST) have been developed for a detailed vertical and lateral delineation of redox zones in contaminated aquifers. The RST have the potential to become an integral part of a data acquisition strategy for monitored natural attenuation (MNA). The tape material, consists of a 2 cm wide synthetic textile coated with reactive manganese dioxide minerals. The RST are submerged into existing monitoring wells for approximately one month. This time period is sufficient to allow for a reaction of the mineral coating with groundwater. The RST are aimed at investigating four different redox-zones in contaminated aquifers: Mn(II)-oxidizing, Mn(IV)-reducing, Fe(III)-reducing and sulfate-reducing. Two RST case studies are presented. The RST investigations on a coal tar contaminated site allowed for a precise lateral and vertical delineation of the contaminant plume using the existing monitoring well network. The RST investigations on a BTEX contaminated site yielded a good correlation of RST data with hydrochemical data at the wells sampled. In the majority of plume wells located 50 m downstream of the source area and beyond, Mn(IV)-reducing environment appeared to be prevailing. Comparing the RST data with hydrochemical data indicated evidence for the transport of transformation products with groundwater flow. The repeated application of the RST facilitated an assessment of the plume dynamics. No significant seasonal variation with respect to the redox zone distribution was observed within the contaminant plume. However, the assessment of the changes in redox conditions over a time period of 2.5 years showed that the iron-reducing zone is shrinking and the sulfate-reducing zone disappeared completely indicating that the contaminant plume might decrease in the near future. Thus, the application of the RST facilitated an assessment of the plume dynamics on a centimeter-scale without the necessity of pumping and treating contaminated groundwater.

Blum, P.; Oeste, F. D.; Melzer, R.; Martus, P.

2006-12-01

3

The use of GPR and VES in delineating a contamination plume in a landfill site: a case study in SE Brazil  

NASA Astrophysics Data System (ADS)

This paper presents the results of the application of the Ground Penetrating Radar (GPR) method, or Georadar, in outlining a zone of contamination due to solid residues at the waste burial site of Rio Claro in the state of São Paulo, SE Brazil. A total of eight GPR profiles with 50- and 100-MHz antennae were surveyed. Six profiles were located within the landfill site and the remaining two were outside. The main objective of the GPR survey was to evaluate the side extension of contamination. A Vertical Electric Sounding (VES) survey was performed at four points within the site in order to investigate the vertical extent of the contamination plume and to define the bottom of the landfill. Two additional VESs were done outside the landfill with the purpose of determining the top of the ground water table and the geoelectric stratigraphy of the background. From the interpretation of the GPR profiles, it was possible to locate the top of the contamination plume and to infer that it was migrating laterally beyond the limits of the waste disposal site. This was observed along the profile situated close to the highway SP-127, which was about 20 m from the limit of the site. The signature of the contaminant appears as a discontinuous reflector that is believed to be a shallow ground water table. The discontinuity is marked by a shadow zone, which is characteristic of conductive contaminant residues. The contamination did not move far enough to reach a sugar cane plantation located at approximately 100 m from the border of the site. In the regions free from contamination, the ground water table was mapped at approximately 10 m of depth, and it was characterized by a strong and continuous reflector. The radar signal penetrated deep enough and enabled the identification of a second reflector at approximately 14 m deep, interpreted as the contact between the Rio Claro and the Corumbata?´ formations. The contact is marked by the presence of gravel characterized by ferruginous concretes, which cause the strong amplitude reflection in the GPR profile. Within the landfill site, the quantitative interpretation of the VES results showed the contamination zone. The base of the landfill varies between 11 and 15 m deep. Outside the landfill site, the VES results showed no indication of contamination and allowed the determination of the top of the ground water table and the contact between the Rio Claro and the Corumbata?´ formations. The results of GPR and VES showed a good agreement and the integrated interpretations were supported by local geology and information from several boreholes, about 17 m depth, on average. The bottom of the landfill reaches a maximum of 14.5 m depth.

Porsani, Jorge L.; Filho, Walter M.; Elis, Vagner R.; Shimeles, Fisseha; Dourado, João C.; Moura, Helyelson P.

2004-03-01

4

Dual wall reverse circulation drilling with multi-level groundwater sampling for groundwater contaminant plume delineation at Paducah Gaseous Diffusion Plant, Paducah, Kentucky  

SciTech Connect

Dual wall reverse circulation (DWRC) drilling was used to drill 48 borings during a groundwater contaminant investigation at the Paducah Gaseous Diffusion Plant, Paducah, Kentucky. This method was selected as an alternative to conventional hollow stem auger drilling for a number of reasons, including the expectation of minimizing waste, increasing the drilling rate, and reducing the potential for cross contamination of aquifers. Groundwater samples were collected from several water-bearing zones during drilling of each borehole. The samples were analyzed for volatile organic compounds using a field gas chromatograph. This approach allowed the investigation to be directed using near-real-time data. Use of downhole geophysical logging, in conjunction with lithologic descriptions of borehole cuttings, resulted in excellent correlation of the geology in the vicinity of the contaminant plume. The total volume of cuttings generated using the DWRC drilling method was less than half of what would have been produced by hollow stem augering; however, the cuttings were recovered in slurry form and had to be dewatered prior to disposal. The drilling rate was very rapid, often approaching 10 ft/min; however, frequent breaks to perform groundwater sampling resulted in an average drilling rate of < 1 ft/min. The time required for groundwater sampling could be shortened by changing the sampling methodology. Analytical results indicated that the drilling method successfully isolated the various water bearing zones and no cross contamination resulted from the investigation.

Smuin, D.R.; Morti, E.E.; Zutman, J.L.; Pickering, D.A.

1995-08-01

5

Dual wall reverse circulation drilling with multi-level groundwater sampling for groundwater contaminant plume delineation at Paducah Gaseous Diffusion Plant, Paducah, Kentucky  

Microsoft Academic Search

Dual wall reverse circulation (DWRC) drilling was used to drill 48 borings during a groundwater contaminant investigation at the Paducah Gaseous Diffusion Plant, Paducah, Kentucky. This method was selected as an alternative to conventional hollow stem auger drilling for a number of reasons, including the expectation of minimizing waste, increasing the drilling rate, and reducing the potential for cross contamination

D. R. Smuin; E. E. Morti; J. L. Zutman; D. A. Pickering

1995-01-01

6

The use of GPR and VES in delineating a contamination plume in a landfill site: a case study in SE Brazil  

Microsoft Academic Search

This paper presents the results of the application of the Ground Penetrating Radar (GPR) method, or Georadar, in outlining a zone of contamination due to solid residues at the waste burial site of Rio Claro in the state of São Paulo, SE Brazil. A total of eight GPR profiles with 50- and 100-MHz antennae were surveyed. Six profiles were located

Jorge L. Porsani; Walter M. Filho; Vagner R. Elis; Fisseha Shimeles; João C. Dourado; Helyelson P. Moura

2004-01-01

7

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

8

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

9

Microbial populations in contaminant plumes  

NASA Astrophysics Data System (ADS)

Efficient biodegradation of subsurface contaminants requires two elements: (1) microbial populations with the necessary degradative capabilities, and (2) favorable subsurface geochemical and hydrological conditions. Practical constraints on experimental design and interpretation in both the hydrogeological and microbiological sciences have resulted in limited knowledge of the interaction between hydrogeological and microbiological features of subsurface environments. These practical constraints include: (1) inconsistencies between the scales of investigation in the hydrogeological and microbiological sciences, and (2) practical limitations on the ability to accurately define microbial populations in environmental samples. However, advances in application of small-scale sampling methods and interdisciplinary approaches to site investigations are beginning to significantly improve understanding of hydrogeological and microbiological interactions. Likewise, culture-based and molecular analyses of microbial populations in subsurface contaminant plumes have revealed significant adaptation of microbial populations to plume environmental conditions. Results of recent studies suggest that variability in subsurface geochemical and hydrological conditions significantly influences subsurface microbial-community structure. Combined investigations of site conditions and microbial-community structure provide the knowledge needed to understand interactions between subsurface microbial populations, plume geochemistry, and contaminant biodegradation. La biodégradation efficace des polluants souterrains requiert deux éléments: des populations microbiennes possédant les aptitudes nécessaires à la dégradation, et des conditions géochimiques et hydrologiques souterraines favorables. Des contraintes pratiques sur la conception et l'interprétation des expériences à la fois en microbiologie et en hydrogéologie ont conduit à une connaissance limitée des interactions entre les phénomènes hydrogéologiques et microbiologiques des environnements souterrains. Ces contraintes pratiques sont dues à des contradictions entre les échelles d'étude de l'hydrogéologie et de la microbiologie et à des limitations pratiques sur la capacitéà définir avec précision les populations microbiennes dans les échantillons. Cependant, des progrès dans l'application de méthodes d'échantillonnage à l'échelle locale et des approches pluridisciplinaires des études de terrain ont commencéà améliorer de façon significative notre compréhension des interactions hydrogéologiques et microbiologiques. De plus, les analyses moléculaires et sur les cultures des populations microbiennes présentes dans les panaches de pollution souterraine ont mis en évidence une adaptation significative de ces populations aux conditions environnementales du panache. Les résultats d'études récentes laissent penser que la variabilité des conditions géochimiques et hydrologiques souterraines influence significativement la structure des communautés microbiennes souterraines. Des recherches combinées sur les conditions de terrain et sur la structure des communautés microbiennes apportent les informations nécessaires à la compréhension des interactions entre les populations microbiennes souterraines, la géochimie du panache et la biodégradation du polluant. Para que la biodegradación de los contaminantes en el subsuelo sea eficiente se requiere: (1) una población microbiana con capacidad de degradación y (2) unas condiciones hidrológicas y geoquímicas favorables. Las restricciones de tipo práctico en los diseños y la interpretación de experimentos, tanto hidrogeológicos como microbiológicos, han dado lugar a un conocimiento limitado de la interrelación entre estas dos ciencias por lo que respecta al subsuelo. Estas restricciones incluyen: (1) inconsistencias entre las escalas de investigación en ambas ciencias (hidrogeología y microbiología) y (2) limitaciones prácticas para definir poblaciones microbianas en las muestras. Sin embargo, lo

Haack, Sheridan K.; Bekins, Barbara A.

10

Delineating landfill leachate discharge to an arsenic contaminated waterway.  

PubMed

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 arsenic contamination in a pond abutting a closed landfill. Subsurface hydrology and ground-water chemistry were evaluated in the aquifer between the landfill and the pond during the period 2005-2009 employing a network of wells to delineate the spatial and temporal variability in subsurface conditions. These observations were compared with concurrent measures of ground-water seepage and surface water chemistry within a shallow cove that had a historical visual record of hydrous ferric oxide precipitation along with elevated arsenic concentrations in shallow sediments. Barium, presumably derived from materials disposed in the landfill, served as an indicator of leachate-impacted ground water discharging into the cove. Evaluation of the spatial distributions of seepage flux and the concentrations of barium, calcium, and ammonium-nitrogen indicated that the identified plume primarily discharged into the central portion of the cove. Comparison of the spatial distribution of chemical signatures at depth within the water column demonstrated that direct discharge of leachate-impacted ground water was the source of highest arsenic concentrations observed within the cove. These observations demonstrate that restoration of the impacted surface water body will necessitate control of leachate-impacted ground water that continues to discharge into the cove. PMID:22018591

Ford, Robert G; Acree, Steven D; Lien, Bob K; Scheckel, Kirk G; Luxton, Todd P; Ross, Randall R; Williams, Aaron G; Clark, Patrick

2011-11-01

11

Characterization of a landfill-derived contaminant plume in glacial and bedrock aquifers, Dupage County, Illinois  

Microsoft Academic Search

In this study of the Blackwell landfill, DuPage County, Illinois, the contaminant plume is delineated and related to the site history and hydrogeology. Leachate leakage is attributed partly to landfill construction problems. The landfill is located partly on a sand-and-gravel aquifer and partly on thick, low permeability till, all overlying an important dolomite aquifer. A roughly concentric contaminant plume surrounds

Vagt

1987-01-01

12

Mapping degrading organic contaminant plumes with spontaneous potential: Why does it not always work?  

Microsoft Academic Search

Organic contaminants in groundwater such as those in landfill leachate or hydrocarbon spills are of concern when they impact drinking water. The delineation of these contaminants is therefore of interest and spontaneous potential (SP) has been proposed as a rapid, simple and inexpensive method for mapping a plume from the ground surface. It has been suggested that SP could be

S. Forté; L. R. Bentley

2010-01-01

13

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

14

Delineating Reactive Natural Attenuation Zones: Multi-level Sampling in an Ammonium Plume  

NASA Astrophysics Data System (ADS)

Current natural attenuation monitoring involves observing concentrations along some transect parallel to flow, often in long--screened observation wells. Vertically integrated geochemical signals essentially compresses 3D-problems into 2D ones and the loss of process resolution does not allow for robust plume transport prediction. On the other hand, a monitoring approach that is based on process quantification will yield field data necessary for current natural attenuation assessment and allow more accurate prediction to plume behaviour. To quantify these spatially discrete processes, the resolution of sampling points must be higher to delineate reactive zones, that account for the bulk of natural attenuation. These reactive zones are dependent on aquifer properties, contaminant type, redox zonation and other factors. In many cases, the plume fringe will be the most active zone, because influx of certain nutrients necessary to support bacteria will be greatest in these zones. Most importantly, consortia of degrading bacteria are dependent on supply of electron--acceptors such as dissolved {O2} and nitrate from background ground water and recharge; electron--acceptors are rapidly consumed at the fringes and concentrations decrease significantly towards the centre of the plume. Thus, if a process--based approach is to be achieved, one has to focus not only on the overall extent and mass of a contaminant plume, but, more importantly, on a sound analysis of the most reactive zones. The site of a former coal processing plant in the UK was chosen as a field site where the afore--mentioned hypothesis is currently being investigated by means of two recently installed multi--level samplers. Previous investigations have located an ammonium plume at the site with outwash from the thick unsaturated zone as ongoing source since the demolition of the actual plant in 1970. The conceptual model drawn from the analysis of these data shows that certain zones exhibit higher rates of degradation than others, but the extent of these zones and rates of degradation could not be determined with the sampling methods used in previous investigations. Spacing between the sampling ports in the newly installed multi--level samplers is 25cm across the top fringe of the plume, and the ground water is analysed for contaminants, general redox chemistry of the aquifer, and isotopes. The analysis of groundwater samples from a first sampling round performed in late summer 2003 shows that i) nitrification is ongoing at the upper fringe in a zone about 0.5m thick, but concentrations of nitrate encountered at the ports across the fringe are higher that derived from the degradation of available ammonium; ii) concentrations of electron--donors and --acceptors change rapidly in the fringe--zone; iii) inside the plume, different processes are prevalent than at the upper fringe; iv) a trend in the isotopic composition appears to indicate a distinct consumption of carbon and sulphate by microbial activity, but these data are not unequivocal and should only be used as supportive evidence.

Hüttmann, A.; Wilson, R. D.; Thornton, S. F.; Lerner, D. N.

2003-12-01

15

Detection of contaminant plumes released from landfills  

NASA Astrophysics Data System (ADS)

Contaminant leaks released from landfills are a significant threat to groundwater quality. The groundwater detection monitoring systems installed in the vicinity of such facilities are vital. In this study the detection probability of a contaminant plume released from a landfill has been investigated by means of both a simulation and an analytical model for both homogeneous and heterogeneous aquifer conditions. The results of the two models are compared for homogeneous aquifer conditions to illustrate the errors that might be encountered with the simulation model. For heterogeneous aquifer conditions contaminant transport is modelled by an analytical model using effective (macro) dispersivities. The results of the analysis show that the simulation model gives the concentration values correctly over most of the plume length for homogeneous aquifer conditions, and that the detection probability of a contaminant plume at given monitoring well locations match quite well. For heterogeneous aquifer conditions the approximating analytical model based on effective (macro) dispersivities yields the average concentration distribution satisfactorily. However, it is insufficient in monitoring system design since the discrepancy between the detection probabilities of contaminant plumes at given monitoring well locations computed by the two models is significant, particularly with high dispersivity and heterogeneity.

Yenigül, N. B.; Hendsbergen, A. T.; Elfeki, A. M. M.; Dekking, F. M.

2006-06-01

16

Characterization of a landfill-derived contaminant plume in glacial and bedrock aquifers, NE Illinois  

Microsoft Academic Search

Groundwater contamination by organic and inorganic chemicals is a regional and national problem; landfills are major potential contaminant sources. In the study of the Blackwell landfill, DuPage County, Illinois the contaminant plume is delineated and related to the site history and hydrogeology. Leachate leakage is attributed partly to landfill construction problems. The landfill is located partly on a sand-and-gravel aquifer

C. J. Booth; P. J. Vagt

1986-01-01

17

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

NASA Astrophysics Data System (ADS)

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, induced polarization and electrical resistivity techniques were used to monitor the plume. We propose that an exceptionally strong (>800 mV peak to peak) dipolar SP anomaly represents a microbial fuel cell operating in the subsurface. The electromagnetic and electrical geophysical data delineated a shallow aerobic perched water body containing conductive gasworks waste which acts as the abiotic cathode of microbial fuel cell. This is separated from the plume below by a thin clay layer across the site. Microbiological evidence suggests that degradation of organic contaminants in the plume is dominated by the presence of ammonium and its subsequent degradation. We propose that the degradation of contaminants by microbial communities at the edge of the plume provides a source of electrons and acts as the anode of the fuel cell. We hypothesize that ions and electrons are transferred through the clay layer that was punctured during the trial pitting phase of the investigation. This is inferred to act as an electronic conductor connecting the biologically mediated anode to the abiotic cathode. Integrated electrical geophysical techniques appear well suited to act as rapid, low cost sustainable tools to monitor biodegradation.

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

2010-09-01

18

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

19

Combining multivariate statistical analysis with geographic information systems mapping: a tool for delineating groundwater contamination  

Microsoft Academic Search

Multivariate Statistical Analysis (MSA) has successfully been coupled with geographic information system (GIS) mapping tools to delineate zones of aquifer contamination potential. While delineating contaminants is key to site remediation, it is often compromised by a poor understanding of hydrogeologic conditions, and by uncertainties in contaminant observations. MSA provides improved estimates of contamination potential by augmenting observed contaminant concentrations with

Silas E. Mathes; Todd C. Rasmussen

2006-01-01

20

Contamination Control and Plume Assessment of Low-Energy Thrusters.  

National Technical Information Service (NTIS)

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 verif...

J. J. Scialdone

1993-01-01

21

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

PubMed

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. PMID:12413210

Rubin, Hillel; Buddemeier, Robert W

2002-11-01

22

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

23

Delineation of a landfill leachate plume and flow channels in coastal sands near Christchurch, New Zealand, using a shallow electromagnetic survey method  

NASA Astrophysics Data System (ADS)

The Burwood landfill, which serves the city of Christchurch, New Zealand, is situated on coastal sands underlain by a sequence of aquifers and aquitards. Groundwater flow is toward the coast, located approximately 700 m from the landfill boundary. Shortly after completion of the first phase of the landfill, an array of wells was installed to detect any contaminant from the landfill. Leachate was detected in the wells closest to the landfill. A shallow electromagnetic (EM31) survey was carried out between the landfill and the coast, in order to delineate any leachate plume that may be present. On the basis of the geophysical results, a contaminant plume and buried channels connected to the coast were identified. Leachate flow initially occurs in what is probably a channel or pair of channels. Downgradient, the plume spreads out to the north and south as it moves eastward toward the coast. Using the geophysical results as a guide, a new set of wells was installed to confirm the presence of high leachate concentrations. Pore-water sampling confirms the presence of a leachate plume.

Nobes, David C.; Armstrong, Mark J.; Close, Murray E.

2000-06-01

24

Hydrogeology and leachate plume delineation at a closed municipal landfill, Norman, Oklahoma  

USGS Publications Warehouse

The City of Norman operated a solid-waste municipal landfill at two sites on the Canadian River alluvium in Cleveland County, Oklahoma from 1970 to 1985. The sites, referred to as the west and east cells of the landfill, were originally excavations in the unconsolidated alluvial deposits and were not lined. Analysis of ground-water samples indicate that leachate from the west cell is discharging into an adjacent abandoned river channel, referred to as the slough, and is migrating downgradient in ground water toward the Canadian River. The report describes the hydrogeologic features at the landfill, including the topography of the bedrock, water-level changes in the alluvial aquifer, and delineates the leachate plume using specific conductance data. The leading edge of the leachate plume along the 35-80 transect extended over 250 meters downgradient of the west cell. The leading edge of the leachate plume along the 40-SOUTH transect had moved about 60 meters from the west cell in a south-southwesterly direction and had not moved past the slough as of 1997. Specific conductance measurements exceeding 7,000 microsiemens per centimeter at site 40 indicate the most concentrated part of the plume remained in the upper half of the alluvial aquifer adjacent to the west cell. The direction of ground-water flow in the alluvial aquifer surrounding the landfill was generally north-northeast to south-southwest toward the river. However, between the west cell and the slough along the 40-SOUTH transect, head measurements indicate a directional change to the east and southeast toward a channel referred to as the sewage outfall. Near the 35-80 transect, at 0.5 meter below the water table and at the base of the aquifer, the direction of ground-water flow was south-southeast with a gradient of about 30 centimeters per 100 meters. Generally, ground-water levels in the alluvial aquifer were higher during the winter months and lower during summer months, due to a normal decrease in precipitation and increased evapotranspiration in the summer. Hydrographs show temporal water-level changes in ground water and the slough, indicating a hydrologic connection between the alluvial aquifer and the slough.

Becker, Carol J.

2002-01-01

25

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

26

Contaminant plumes containment and remediation focus area. Technology summary  

SciTech Connect

EM has established a new approach to managing environmental technology research and development in critical areas of interest to DOE. The Contaminant Plumes Containment and Remediation (Plumes) Focus Area is one of five areas targeted to implement the new approach, actively involving representatives from basic research, technology implementation, and regulatory communities in setting objectives and evaluating results. This document presents an overview of current EM activities within the Plumes Focus Area to describe to the appropriate organizations the current thrust of the program and developing input for its future direction. The Plumes Focus Area is developing remediation technologies that address environmental problems associated with certain priority contaminants found at DOE sites, including radionuclides, heavy metals, and dense non-aqueous phase liquids (DNAPLs). Technologies for cleaning up contaminants of concern to both DOE and other federal agencies, such as volatile organic compounds (VOCs), polychlorinated biphenyls (PCBs), and other organics and inorganic compounds, will be developed by leveraging resources in cooperation with industry and interagency programs.

NONE

1995-06-01

27

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 ...

28

Contamination control and plume assessment of low-energy thrusters  

NASA Astrophysics Data System (ADS)

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.

1993-05-01

29

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

30

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...

31

Shuttle primary reaction control system engine exhaust plume contamination effects  

NASA Technical Reports Server (NTRS)

Space Shuttle proximity operations constitute an important part of the SSF induced external environment. The impingement of primary reaction control system (PRCS) engine plumes on SSF functional surfaces during docking or berthing and separation leads to concerns about molecular contamination and high speed particle impact. The Shuttle Plume Impingement flight Experiment (SPIE) was designed to provide a direct measure of both the molecular contamination and particle impact rates produced by Shuttle PRCS engines in the LEO environment. The measured permanent deposition produced by PRCS engine firings was less than that assumed in current SSF programatic assessments. Only two to three possible high velocity particle impact pits were observed on the RMS end effector hardware.

Koontz, Steve; Ehlers, Horst; Pedley, Mike; Cross, John; Hakes, Charles

1993-01-01

32

Comparison of E{sub h} and H{sub 2} measurements for delineating redox processes in a contaminated aquifer  

SciTech Connect

Measurements of oxidation-reduction potential (E{sub h}) and concentrations of dissolved hydrogen (H{sub 2}) were made in a shallow groundwater system contaminated with solvents and jet fuel to delineate the zonation of redox processes. E{sub h} measurements ranged from +69 to -158 mV in a cross section of the contaminated plume and accurately delineated oxic from anoxic groundwater. Plotting measured E{sub h} and pH values on an equilibrium stability diagram indicated that Fe(III) reduction was the predominant redox process in the anoxic zone and did not indicate the presence of methanogenesis and sulfate reduction. In contrast, measurements of H{sub 2} concentrations indicated that methanogenesis predominated in heavily contaminated sediments near the water table surface (H{sub 2} {approx} 7.0 nM) and that the methanogenic zone was surrounded by distinct sulfate-reducing (H{sub 2} {approx} 1-4 nM) and Fe(III)-reducing (H{sub 2} {approx} 0.1-0.8 nM) zones. The presence of methanogenesis, sulfate reduction, and Fe(III) reduction was confirmed by the distribution of dissolved oxygen, sulfate, Fe(II), and methane in groundwater. These results show that H{sub 2} concentrations were more useful for identifying anoxic redox processes than E{sub h} measurements in this groundwater system. 16 refs., 6 figs., 1 tab.

Chapelle, F.H.; Bradley, P.M. [U.S. Geological Survey, Columbia, SC (United States)] [U.S. Geological Survey, Columbia, SC (United States); Haack, S.K. [Geological Survey, Lansing, MI (United States)] [Geological Survey, Lansing, MI (United States); Adriaens, P. [Univ. of Michigan, Ann Arbor, MI (United States)] [Univ. of Michigan, Ann Arbor, MI (United States); Henry, M.A. [National Center for Integrated Bioremediation Research, Oscoda, MI (United States)] [National Center for Integrated Bioremediation Research, Oscoda, MI (United States)

1996-12-01

33

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

34

Comparison of E(h) and H2 measurements for delineating redox processes in a contaminated aquifer  

USGS Publications Warehouse

Measurements of oxidation-reduction potential (E(h)) and concentrations of dissolved hydrogen (H2) were made in a shallow groundwater system contaminated with solvents and jet fuel to delineate the zonation of redox processes. E(h) measurements ranged from +69 to -158 mV in a cross section of the contaminated plume and accurately delineated oxic from anoxic groundwater. Plotting measured E(h) and pH values on an equilibrium stability diagram indicated that Fe-(III) reduction was the predominant redox process in the anoxic zone and did not indicate the presence of methanogenesis and sulfate reduction. In contrast, measurements of H2 concentrations indicated that methanogenesis predominated in heavily contaminated sediments near the water table surface (H2 ~ 7.0 nM) and that the methanogenic zone was surrounded by distinct sulfate-reducing (H2 ~ 1-4 nM) and Fe-(III)-reducing (H2 ~ 0.1-0.8 nM) zones. The presence of methanogenesis, sulfate reduction, and Fe(III) reduction was confirmed by the distribution of dissolved oxygen, sulfate, Fe(II), and methane in groundwater. These results show that H2 concentrations were more useful for identifying anoxic redex processes than E(h) measurements in this groundwater system. However, H2-based redox zone delineations are more reliable when H2 concentrations are interpreted in the context of electron-acceptor (oxygen, nitrate, sulfate) availability and the presence of final products [Fe(II), sulfide, methane] of microbial metabolism.

Chapelle, F. H.; Haack, S. K.; Adriaens, P.; Henry, M. A.; Bradley, P. M.

1996-01-01

35

Mapping degrading organic contaminant plumes with spontaneous potential: Why does it not always work?  

NASA Astrophysics Data System (ADS)

Organic contaminants in groundwater such as those in landfill leachate or hydrocarbon spills are of concern when they impact drinking water. The delineation of these contaminants is therefore of interest and spontaneous potential (SP) has been proposed as a rapid, simple and inexpensive method for mapping a plume from the ground surface. It has been suggested that SP could be used to identify zones of high redox potential gradients that form a halo around a degrading contaminant plume. We conducted SP surveys on two hydrocarbon contaminated sites in Alberta. Neither site showed the expected negative anomaly. The computer code MIN3P was used to simulate the transport and geochemical evolution of a hydrocarbon spill. The results from one time step were used to represent the distribution of the chemical species that is the source of SP anomalies. Using a finite element code, we modelled the SP signature due to two types of hypothetical source terms. The first type is sources due to diffusion, modelled using the Nernst-Plank equation. The diffusion model does not produce anomalies at the surface greater than 3 mV which would be in the range of error and normal background variations in the field. The second type is sources due to redox potentials and they were modelled using an equation proposed by Revil et al. (Journal of Contaminant Hydrology, 2009). This equation assumes there is a transition zone where charge transfer is mainly by a hypothetical electronic conductor such as microbial nanowires. This assumption implies that the electrical conductivity should be higher in this zone than in the surrounding porous medium. Since the plume is not at thermodynamic equilibrium, redox potential is not strictly defined, so we used the iron couple to generate redox potential values. If the conductivity of the electronic conductor transition zone was greater than 1500 times the background, the surface anomalies were less than 20 mV. As the electrical conductivity of the transition zone declined to background values, the surface SP anomaly increased to around 200 mV. Consequently, it appears that if an electronic conduction zone develops, it must have a moderate electrical conductivity to generate large potentials at the surface. Since our sites show no significant anomalies over the plumes, we hypothesize that either 1) the electronic conduction redox potential hypothesis is not correct or 2) that the electronic conduction zone did not evolve. In either case, SP may only be useful for mapping redox potential under specific subsurface conditions.

Forté, S.; Bentley, L. R.

2010-12-01

36

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

37

PLUMES  

EPA Science Inventory

PLUMES INCLUDES TWO INITIAL DILUTION PLUME MODELS (RSB AND UM) AND A MODEL INTERFACE MANAGER FOR PREPARING COMMON INPUT AND RUNNING THE MODELS. TWO FARFIELD ALGORITHMS ARE AUTOMATICALLY INITIATED BEYOND THE ZONE OF INITIAL DILUTION. PLUMES ALSO INCORPORATES THE FLOW CLASSIFICAT...

38

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

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

GIS-based colour composites and overlays to delineate heavy metal contamination zones in the shallow alluvial aquifers, Ankaleshwar industrial estate, south Gujarat, India  

NASA Astrophysics Data System (ADS)

In an attempt to delineate heavy metal contamination precincts and to evaluate the extent and degree of toxic levels, besides their possible sources, 38 water samples from Ankaleshwar Industrial Estate, south Gujarat, India were analyzed. By clutching geochemical analyses and GIS-based colour composites areas depicting anomalously high concentration of heavy metals (Mo, Zn, Pb, Ni, Co, Cd, etc.) in the groundwater were revealed. The multicomponent overlays in grey-scale facilitated in identifying situates of heavy metal ‘hot spots’, and lateral protuberances of the contamination plume around defile stretch of the main stream Amla Khadi flowing through the area. The multiple pollution plumes emerging from other parts of the area further coincide with effluent laden streams and small channels indicating industrial establishments as major sources of groundwater contamination. Influent nature of the streams, accelerated infiltration process, high mass influx and shallow groundwater table are the factors conducive for easy access of heavy metals to the phreatic aquifers affecting over 20 km2 area. On the basis of P/ U ratios (concentration of metals in polluted water to unpolluted water), geogenic and anthropogenic sources have been identified. Very high levels of technogenic elements present in the ground water raise concerns about possible migration into food crops, as the area is an important horticultural locale and is highly cultivated.

Kumar, Suyash; Shirke, K. D.; Pawar, N. J.

2008-03-01

41

On the link between contaminant source release conditions and plume prediction uncertainty.  

PubMed

The initial width of contaminant plumes is known to have a key influence on expected plume development, dispersion and travel time statistics. In past studies, initial plume width has been perceived identical to the geometric width of a contaminant source or injection volume. A recent study on optimal sampling layouts (Nowak et al., 2009) showed that a significant portion of uncertainty in predicting plume migration stems from the uncertain total hydraulic flux through the source area. This result points towards a missing link between source geometry and plume statistics, which we denote as the effective source width. We define the effective source width by the ratio between the actual and expected hydraulic fluxes times the geometric source width. The actual hydraulic flux through the source area is given by individual realizations while the expected one represents the mean over the ensemble. It is a stochastic quantity that may strongly differ from the actual geometric source width for geometrically small sources, and becomes identical only at the limit of wide sources (approaching ergodicity). We derive its stochastic ensemble moments in order to explore the dependency on source scale. We show that, if the effective source width is known rather than the geometric width, predictions of plume development can greatly increase in predictive power. This is illustrated on plume statistics such as the distribution of plume length, average width, transverse dispersion, total mass flux and overall concentration variance. The analysis is limited to 2D depth-averaged systems, but implications hold for 3D cases. PMID:20541835

de Barros, Felipe P J; Nowak, Wolfgang

2010-07-30

42

Storage and Release of Contaminants in Low Flow Zones in Source and Plumes  

Microsoft Academic Search

Through a rich body of published research and recent studies at Colorado State University it has been shown that dissolved and sorbed phase contaminants in low flow zones can act as persistent sources of groundwater contamination. This occurs both in source zones and plumes. Examples of low flow zones included silt beds bounded by sand and sand layers bounded by

T. C. Sale; L. A. Doner; E. S. Seger

2006-01-01

43

Hydrogeological factors affecting the multiple plumes of chlorinated contaminants in an industrial complex, Wonju, Korea  

Microsoft Academic Search

Apparent plume attenuations of multiple chlorinated contaminants such as TCE, carbon tetrachloride, and its daughter products at an industrial complex, Wonju, Korea were examined through various hydraulic tests and six rounds of groundwater quality analyses. Aquifer media properties and hydrogeologic factors affecting the distribution and attenuation of multiple contaminants were investigated and key attributes were evaluated. The study area has

J. Yang; D. Kaown; H. Lee; K. Lee

2010-01-01

44

Phosphorus in a ground-water contaminant plume discharging to Ashumet Pond, Cape Cod, Massachusetts, 1999  

USGS Publications Warehouse

The discharge of a plume of sewagecontaminated ground water emanating from the Massachusetts Military Reservation to Ashumet Pond on Cape Cod, Massachusetts, has caused concern about excessive loading of nutrients, particularly phosphorus, to the pond. The U.S. Air Force is considering remedial actions to mitigate potentially adverse effects on the ecological characteristics of the pond from continued phosphorus loading. Concentrations as great as 3 milligrams per liter of dissolved phosphorus (as P) are in ground water near the pond's shoreline; concentrations greater than 5 milligrams per liter of phosphorus are in ground water farther upgradient. Temporary drive-point wells were used to collect water samples from 2 feet below the pond bottom to delineate concentration distributions in the pore waters of the pond-bottom sediments. Measurements in the field of specific conductance and colorimetrically determined orthophosphate concentrations provided real-time data to guide the sampling. The contaminant plume discharges to the Fishermans Cove area of Ashumet Pond as evidenced by elevated levels of specific conductance and boron, which are chemically conservative indicators of the sewage-contaminated ground water. Concentrations of nonconservative species, such as dissolved phosphorus, manganese, nitrate, and ammonium, also were elevated above background levels in ground water discharging to the pond, but in spatially complex distributions that reflect their distributions in ground water upgradient of the pond. Phosphorus concentrations exceeded background levels (greater than 0.10 milligram per liter) in the pond-bottom pore water along 875 feet of shoreline. Greatest concentrations (greater than 2 milligrams per liter) occurred within 30 feet of the shore in an area about 225 feet long. Calculations of phosphorus flux in the aquifer upgradient of Ashumet Pond, as determined from water-flux estimates from a steady-state ground-water-flow model and phosphorus concentrations (in 1999) from multilevel samplers about 75 feet upgradient of the pond, indicate that dissolved phosphorus moves towards the pond and discharges to it with the inflowing ground water at a rate as high as about 316 kilograms per year.

McCobb, Timothy D.; LeBlanc, Denis R.; Walter, Donald A.; Hess, Kathryn M.; Kent, Douglas B.; Smith, Richard L.

2003-01-01

45

A controlled field experiment on groundwater contamination by a multicomponent DNAPL: dissolved-plume retardation  

Microsoft Academic Search

A natural gradient emplaced-source (ES) controlled field experiment was conducted at the Borden aquifer research site, Ontario, to study the transport of dissolved plumes emanating from residual dense nonaqueous-phase liquid (DNAPL) source zones. The specific objective of the work presented here is to determine the effects of solute and co-solute concentrations on sorption and retardation of dissolved chlorinated solvent-contaminant plumes.

Michael O Rivett; Richelle M Allen-King

2003-01-01

46

Isotopic Systematics (U, nitrate and Sr) of the F-Area Acidic Contamination Plume at the Savannah River Site: Clues to Contaminant History and Mobility  

NASA Astrophysics Data System (ADS)

Seepage basins in the F-Area of the Savannah River Site were used from 1955 to 1989 for the disposal of low-level radioactive acidic (ave. pH ˜2.9) waste solutions from site operations involving irradiated uranium billets and other materials used in the production of radionuclides. These disposal activities resulted in a persistent acidic groundwater plume (pH as low as 3.2) beneath the F-Area including contaminants such as tritium, nitrate, 90Sr, 129I and uranium and that has impinged on surface water (Four Mile Branch) about 600 m from the basins. After cessation of disposal in 1989, the basins were capped in 1991. Since that time, remediation has consisted of a pump-and-treat system that has recently been replaced with in situ treatment using a funnel-and-gate system with injection of alkaline solutions in the gates to neutralize pH. In order to delineate the history of contamination and the current mobility and fate of contaminants in F-Area groundwater, we have undertaken a study of variations in the isotopic compositions of U (234U/238U, 235U/238U, 236U/238U), Sr (87Sr/86Sr) and nitrate (?15N, ?18O) within the contaminant plume. This data can be used to trace U transport within the plume, evaluate chemical changes of nitrate, and potentially track plume/sediment chemical interaction and trace the migration of 90Sr. We have analyzed a suite of groundwater samples from monitoring wells, as well as pore-water samples extracted from aquifer sediment cores to map out the isotopic variation within the plume. The isotopic compositions of U from well samples and porewater samples are all consistent with the variable burn-up of depleted U. The variation in U isotopic composition requires at least three different endmembers, without any significant influence of background natural U. The ?15N and ?18O of nitrate from F-Area plume groundwater are distinct both from natural and unaltered synthetic nitrate, and likely represents fractionation due to waste volume reduction processes. In detail, the variation in the isotopic composition of F-Area nitrate does not support biologic denitrification within the plume. However, the isotopic composition of a surface water sample is consistent with denitrification occurring along the flow path between the plume seep-line and the surface stream. Strontium from F-Area groundwater samples covers a wide range in concentration (<<20 to 145 ppb) and 87Sr/86Sr (0.7096 to 0.7133). There is no systematic relationship between 87Sr/86Sr & 90Sr or 1/[Sr] suggesting possible Sr exchange with clays minerals. The isotopic compositions of groundwater and porewater samples vary systematically with sampling depth below the water table as illustrated by U isotopic data for depth discrete porewater samples and the ?15N of well samples. There appears to be a shallow zone within the top 10 ft of the aquifer, defined by reversals in the trends of U isotopic data and nitrate ?18O.

Christensen, J. N.; Conrad, M. E.; Bill, M.; Denham, M.; Wan, J.; Rakshit, S.; Stringfellow, W. T.; Spycher, N.

2010-12-01

47

Breakthrough of Contaminant Plumes in Saturated Volcanic Rock: Implications from the Yucca Mountain Site  

NASA Astrophysics Data System (ADS)

This paper presents a study of transverse plume spreading and its effect on breakthrough curves (BTCs), using literature survey and model analysis of field-scale behavior. Such BTCs at compliance boundaries are often used as performance measures for a site. The example considered here is that of the saturated zone (SZ) at the Yucca Mountain Project (YMP) site, Nevada. The SZ at the YMP site occurs partly in fractured volcanic rock formations and partly in alluvial formations. This paper addresses two questions regarding transport of contaminant plumes in saturated volcanic rocks: 1) are any occurrences of broad contaminant plumes in fractured saturated rock documented in the literature, and 2) based on model predictions, what are the effects of lateral plume spreading on downstream BTCs. The results of a literature survey on the occurrences of radionuclide or tracer plumes in saturated, fractured rocks world-wide are presented. Three sites with reported plume data - Idaho National laboratory (INL), Oak Ridge (ORNL), and Hanford - are discussed in some detail, along with summaries of work at some sites underlain by unconsolidated rocks for comparison. Plumes reported with substantial lateral spreading include a tritium plume at INL, a tritium plume in Melton Valley at ORNL, and a chloride plume at Hanford. The results of the survey show that occurances of plumes with transverse spreading are documented in the literature. A numerical model of transport through the fractured and porous formations at the YMP site is used for accessing the influence of transverse dispersion on the BTCs at the compliance boundary. The model incorporates dual-porosity flow with solute diffusion in fractured-rock formations, along with linear sorption of solutes on the rock matrix. A flow model using a site-specific hydrological framework model forms the basis of the transport model. The flow model was calibrated to measured head data and boundary fluxes derived from the regional model, and was validated using site-specific information. At the location of the compliance boundary, the length-to-width ratio of a conservative solute plume originating from a distributed source decreases from about 20:1 to about 4:1 as the horizontal transverse dispersivity is varied from 0.05 m to 10 m. This lateral spreading does not directly affect the BTCs integrated across the entire model width at the compliance boundary.

Kelkar, S.; Tucci, P.; Srinivasan, G.; Roback, R.; Robinson, B.; Rehfeld, K.

2008-12-01

48

An application of geoelectrical methods for contamination plume recognition in Urbanowice waste disposal  

NASA Astrophysics Data System (ADS)

The purpose of this work was to detect groundwater pollution and to identify the conditions of soil and groundwater near the Urbanowice landfill site using geoelectrical measurements. Presented measurements are preliminary results from tested site and are beginning of continuous monitoring. Contamination outflows detected by resistivity and IP technique show a good correlation with available hydrological data. Contamination plume were found in Eastern part of survey profil.

Mycka, Mateusz; Mendecki, Maciej Jan

2013-09-01

49

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...

50

Delineation of fluoride contaminated groundwater around a hot spring in Nayagarh, Orissa, India using geochemical and resistivity studies  

Microsoft Academic Search

Geochemical and geoelectrical investigations were carried out around a hot spring near village Singhpur, Nayagarh District of Orissa to delineate the extent of fluoride contamination in groundwater. Fluoride concentration is observed to be very high in both hot spring and groundwater of Singhpur village compared with surrounding ones. Vertical electrical sounding (VES) studies in the area reveal the presence of

N. Kundu; M. Panigrahi; S. Sharma; S. Tripathy

2002-01-01

51

Hydrogeological factors affecting the multiple plumes of chlorinated contaminants in an industrial complex, Wonju, Korea  

NASA Astrophysics Data System (ADS)

Apparent plume attenuations of multiple chlorinated contaminants such as TCE, carbon tetrachloride, and its daughter products at an industrial complex, Wonju, Korea were examined through various hydraulic tests and six rounds of groundwater quality analyses. Aquifer media properties and hydrogeologic factors affecting the distribution and attenuation of multiple contaminants were investigated and key attributes were evaluated. The study area has vertically heterogeneous properties from top alluvial layer to crystalline rocks while the weathered fractured layer above intact Jurassic biotite granite acts as the main layer for groundwater flow and aqueous phase multiple contaminants migration. Aerial heterogeneity in surface conditions plays an important role for groundwater recharge because the industrial complex is mostly paved by asphalt and concrete. Due to limited recharge area and concentrated precipitation in summer season, seasonal effects of contaminant plume distribution diminish as the distance increase from the area of recharge. This study analyzed how differently the solute and contaminant concentrations response to the seasonal recharge. For the analyses, the study site was divided into three zones and four transects were established. Groundwater and solute mass balances were estimated by computing groundwater and solute mass flux through transects. The effects of groundwater pumping, groundwater flow and contaminant degradation were examined to simulate the solutes and contaminant concentrations. General tendency of the water quality and contaminant concentration were reproducible with the effects of major components such as groundwater recharge, pumping and estimated degradation rate.

Yang, J.; Kaown, D.; Lee, H.; Lee, K.

2010-12-01

52

The Relationship Between Partial Contaminant Source Zone Remediation and Groundwater Plume Attenuation  

NASA Astrophysics Data System (ADS)

Analytical solutions are developed that relate changes in the contaminant mass in a source area to the behavior of biologically reactive dissolved contaminant groundwater plumes. Based on data from field experiments, laboratory experiments, numerical streamtube models, and numerical multiphase flow models, the chemical discharge from a source region is assumed to be a nonlinear power function of the fraction of contaminant mass removed from the source zone. This function can approximately represent source zone mass discharge behavior over a wide range of site conditions ranging from simple homogeneous systems, to complex heterogeneous systems. A mass balance on the source zone with advective transport and first order decay leads to a nonlinear differential equation that is solved analytically to provide a prediction of the time-dependent contaminant mass discharge leaving the source zone. The solution for source zone mass discharge is coupled semi-analytically with a modified version of the Domenico (1987) analytical solution for three-dimensional reactive advective and dispersive transport in groundwater. The semi-analytical model then employs the BIOCHLOR (Aziz et al., 2000; Sun et al., 1999) transformations to model sequential first order parent-daughter biological decay reactions of chlorinated ethenes and ethanes in the groundwater plume. The resulting semi-analytic model thus allows for transient simulation of complex source zone behavior that is fully coupled to a dissolved contaminant plume undergoing sequential biological reactions. Analyses of several realistic scenarios show that substantial changes in the ground water plume can result from the partial removal of contaminant mass from the source zone. These results, however, are sensitive to the nature of the source mass reduction-source discharge reduction curve, and to the rates of degradation of the primary contaminant and its daughter products in the ground water plume. Aziz, C.E., C.J. Newell, J.R. Gonzales, P. Haas, T.P. Clement, and Y. Sun, 2000, BIOCHLOR Natural Attenuation Decision Support System User's Manual Version 1.0, US EPA Report EPA/600/R-00/008 Domenico, P.A., 1987, An analytical model for multidimensional transport of a decaying contaminant species, J. Hydrol., 91: 49-58. Sun, Y., J.N. Petersen, T.P. Clement, and R.S. Skeen, 1999, A new analytical solution for multi-species transport equations with serial and parallel reactions, Water Resour. Res., 35(1): 185-190.

Falta, R. W.

2004-05-01

53

Delineation of soil and groundwater contamination using geophysical methods at a waste disposal site in Çanakkale, Turkey  

Microsoft Academic Search

Direct current (DC) resistivity, self potential (SP) and very low frequency electromagnetic (VLF-EM) measurements are carried\\u000a out to detect the spread of groundwater contamination and to locate possible pathways of leachate plumes, that resulted from\\u000a an open waste disposal site of ?anakkale municipality. There is no proper management of the waste disposal site in which industrial\\u000a and domestic wastes were

M. Ali Kaya; Gülçin Özürlan; Ebru ?engül

2007-01-01

54

Storage and Release of Contaminants in Low Flow Zones in Source and Plumes  

NASA Astrophysics Data System (ADS)

Through a rich body of published research and recent studies at Colorado State University it has been shown that dissolved and sorbed phase contaminants in low flow zones can act as persistent sources of groundwater contamination. This occurs both in source zones and plumes. Examples of low flow zones included silt beds bounded by sand and sand layers bounded by gravel. Primary processes governing storage and release of contaminants in low flow zones include sorption, diffusion, and slow advection. The challenges of stored contaminants are that they can sustain groundwater plumes and adversely affect the timing and magnitude of downgradient water quality improvements associated with remedial actions. The following provides a brief summary of governing processes, implications, and ongoing research. Initially, chlorinated solvents move along the pathways with the greatest transmissivity. This is illustrated in a sand tank study where fluorescein dye in water is pumped through a tank containing interbedded layers of sand and clay. At early time, little if any contamination is present in the low flow layers (clay). With extended time, dissolved phase contaminants are driven into low flow zones by diffusion and/or slow advection. Contaminants in low flow zones are stored in both dissolved and sorbed phases. Removal of the upgradient source reduces contaminant concentrations in transmissive zones and drives releases of contaminants from low flow zones via back diffusion and slow advection. The release process is visually illustrated by the trails of water with fluorescein dye emanating from the clay layers in sand tank studies. Furthermore, analytical data from the tank studies illustrate asymmetrical breakthrough curves with extended tails. Field data from F. E. Warren AFB, WY provides further insights. An iron PRB was installed in 2000. This action reduced TCE concentrations at the barrier by multiple orders of magnitude to values less than 5 ug/L. After five years, TCE concentrations forty and sixty feet down gradient of the barrier dropped by only one order of magnitude. Sustained concentrations of TCE downgradient of the barrier are attributed to desorption and back diffusion from low flow zones. The degree to which stored contaminants can sustain plumes is dependent on site conditions. General conditions that favor sustained release of stored contaminants include: 1) A large degree of geologic heterogeneity, 2) Geologic settings with transmissive zones that are a small fraction of the total volume of the aquifer, 3) Contaminants that have large aqueous solubility, 4) Contaminants that are stable in their physical setting (e.g. chlorinated solvents in oxic environments) 5) Systems with relatively slow groundwater flow rates, 6) Sediments with high fractions of organic carbon, 7) Sites where large amounts of contaminant were released, and 8) Older sites where there has been a large amount of time for contaminants to move into low flow intervals. Primary implications include: 1) Release of stored contaminants can sustain contaminant discharge from source zones, 2) Given near perfect depletion and/or containment of sources, downgradient plumes can persist for extended periods, 3) A large fraction of the total stored contaminant mass can occur outside of source zones, 4) Source zone treatments that solely address transmissive zones may miss substantial contaminant mass in low flow zones and be subject to rebound.

Sale, T. C.; Doner, L. A.; Seger, E. S.

2006-12-01

55

Improving Modeling of Iodine-129 Groundwater Contamination Plumes Using the System Assessment Capability  

SciTech Connect

Years of production of radioactive materials at the Hanford Site in southeastern Washington State has resulted in contamination of surface, subsurface, and surface water environments. Cleanup of the site has been aided by various tools, including computer software used to predict contaminant migration in the future and estimate subsequent impacts. The System Assessment Capability (SAC) is a total systems tool designed to simulate the movement of contaminants from all waste sites at Hanford through the vadose zone, the unconfined aquifer, and the Columbia River. Except for iodine-129, most of the contaminants modeled by SAC have acceptably matched field measurements. The two most likely reasons for the inconsistency between the measured field data and SAC modeled predictions are an underestimated inventory and an overestimated sorption value (Kd). Field data tend to be point measurements taken from near the surface of the unconfined aquifer. Thus, the depth of the iodine-129 contamination plume on the site is not well characterized. Geostatistical analyses of the measured data were conducted to determine the mass of iodine-129 for four assumed plume depths within the unconfined aquifer. Several simulations for two different Kd’s using the initial SAC inventory were run to determine the effect of an overestimated sorption value on SAC modeled predictions. The initial SAC inventory was then increased for the two different Kd’s to determine the influence of an underestimated inventory on SAC modeled predictions. It was found that evidence for both an underestimated inventory and for an overestimated sorption value for iodine-129 exist. These results suggest that the Kd for iodine-129 should be reevaluated and that a more complete inventory must be generated in order to more accurately model iodine-129 groundwater contamination plumes that match available field data.

Dirkes, J.; Nichols, W.E.; Wurstner, S.K.

2004-01-01

56

Migration of a groundwater contaminant plume by stratabound flow in Waste Area Grouping 1 at Oak Ridge National Laboratory, Oak Ridge, Tennessee. Environmental Restoration Program  

Microsoft Academic Search

The discovery of radiologically contaminated groundwater in core hole CH-8 in the western portion of Waste Area Grouping (WAG) 1 at Oak Ridge National Laboratory (ORNL) prompted a detailed investigation to identify the contaminant plume. Utilizing a working hypothesis of stratabound groundwater flow and contaminant transport, investigators analyzed existing subsurface geologic data to predict the contaminant plume discharge location in

R. H. Ketelle; R. R. Lee

1992-01-01

57

Migration of a groundwater contaminant plume by stratabound flow in Waste Area Grouping 1 at Oak Ridge National Laboratory, Oak Ridge, Tennessee  

Microsoft Academic Search

The discovery of radiologically contaminated groundwater in core hole CH-8 in the western portion of Waste Area Grouping (WAG) 1 at Oak Ridge National Laboratory (ORNL) prompted a detailed investigation to identify the contaminant plume. Utilizing a working hypothesis of stratabound groundwater flow and contaminant transport, investigators analyzed existing subsurface geologic data to predict the contaminant plume discharge location in

R. H. Ketelle; R. R. Lee

1992-01-01

58

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

59

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

60

The plume fringe concept - Biodegradation of organic contaminants in subsurface ecosystems  

NASA Astrophysics Data System (ADS)

The biodegradation of organic pollutants in groundwater systems may be limited by the depletion of essential nutrients or the low number of degraders. However, the main problem seems to be the insufficient mixing of e-donors and e-acceptors. Main degradation activities in contaminant plumes are therefore located at their fringes. In order to investigate the ecology of pollutant-degrading microbes, experiments are carried out (1) in 2D-aquifer model systems and (2) sediment cores were drilled at a former gasworks site and a novel high-resolution multilevel sampling well was installed. (1) To assess the importance of individual abiotic (e.g. mixing, toxicity, nutrients) and biotic (e.g. cell distribution and activity, redox tolerance) parameters for biodegradation under well controlled lab conditions, contaminant plumes are generated in 2D-model systems and subsequently inoculated with aerobic and/or anaerobic bacterial strains to investigate biodegradation in a spatially resolved manner. (2) To recognize limitations of biodegradation in a PAH-contaminated aquifer, sediment cores were taken and, at the same site, a high-resolution multilevel well was installed for frequent groundwater sampling with varying spatial resolution (from cm to m range). In both systems, degradation of contaminants is followed by vertically resolved concentration measurements, compound-specific stable isotope (D/H, 13C/12C) analysis and the identification of signature metabolites. Physical-chemical gradients are resolved by means of microsensors and geochemical sediment and water analysis. The spatial distribution of microbial biomass, individual groups of microbes and the presence of functional genes coding for potential degradation activities are investigated using molecular tools. First results of the work, which is embedded in two current projects, will be discussed.

Meckenstock, R. U.; Griebler, C.; Anneser, B.; Winderl, C.; Bauer, R.; Lüders, T.; Kellermann, C.; Selesi, D.

2005-12-01

61

Breakthrough of attenuating contaminant plumes in pumping wells: Analytical model and implications for integral pumping tests  

NASA Astrophysics Data System (ADS)

Monitoring of contaminant plumes and predicting their future fate are essential for effective management of groundwater contaminants. Solute breakthrough curves from operating pumping wells can provide information on the water quality in relatively large aquifer regions, which may be unavailable to instrumentation and direct measurement for practical and/or economical reasons. Relations between spatially varying aquifer concentrations C0(x, y) initially surrounding a well and temporally varying concentrations of subsequently extracted well water, Cp(t), then need to be quantified. However, limited applicability of analytical expressions and numerical inaccuracies related to solving transport equations for converging flow fields hamper such quantifications even in homogeneous aquifers. We use a stream-tube approach and provide a general problem formulation that accounts for first-order degradation and linear, instantaneous, sorption/retardation in heterogeneous aquifers. An analytical expression is obtained for homogeneous aquifer conditions (in the well vicinity), relating any given initial C0(x, y) function and the subsequent contaminant breakthrough Cp(t) in the well. Results for wide plumes subject to first-order degradation show that concentrations at the extraction well will increase as a function of pumping time. This increase is despite the fact that late-time data reflect longer transport paths (to the well), along which mass is removed through degradation. We also derive unique solutions for the inverse problem, in particular considering how the average contaminant concentration Cav (averaged along a control plane through the well within its capture zone, perpendicular to the mean groundwater flow direction) depends on the measurable Cp(t). The solutions demonstrate that the longer the pumping time, the more sensitive the solutions for Cav become to degradation rate constants, which if needed can be determined in situ using multiple control planes.

Bayer-Raich, Martí; Jarsjö, Jerker; Teutsch, Georg

2009-02-01

62

When Does Aquifer Heterogeneity Matter? Predicting the Influence of Alternative Conceptual Models on Contaminant Plume Migration  

NSDL National Science Digital Library

In this exercise, students predict changes in the movement of a dissolved plume in response to remedial pumping in an unconfined aquifer. The underlying conceptual model for the distribution of aquifer and aquitard materials is not known with certainty. Consequently, two alternative end-member conceptualizations are presented to students who are then asked to hypothesize differences in predicted responses at the pumping wells and nearby monitoring wells for each conceptual model. Predictions are compared to actual field data, and students discover that contaminant concentration measurements depend not only on the location of the observation point (in three dimensions), but also on the length of the screened interval through which water samples are collected. The activity is divided into three parts: (1) site/problem description, (2) formulation and testing of hypotheses for pumping wells, and (3) formulation and testing of hypotheses for monitoring wells. The activity gives students practice in three dimensional thinking and reinforces their intuitive understanding of contaminant plume migration in response to natural gradients and engineered stresses.

Lemke, Larry

63

Rapid intrinsic biodegradation of benzene, toluene, and xylenes at the boundary of a gasoline-contaminated plume under natural attenuation.  

PubMed

A groundwater plume contaminated with gasoline constituents [mainly benzene, toluene, and xylenes (BTX)] had been treated by pumping and aeration for approximately 10 years, and the treatment strategy was recently changed to monitored natural attenuation (MNA). To gain information on the feasibility of using MNA to control the spread of BTX, chemical and microbiological parameters in groundwater samples obtained inside and outside the contaminated plume were measured over the course of 73 weeks. The depletion of electron acceptors (i.e., dissolved oxygen, nitrate, and sulfate) and increase of soluble iron were observed in the contaminated zone. Laboratory incubation tests revealed that groundwater obtained immediately outside the contaminated zone (the boundary zone) exhibited much higher potential for BTX degradation than those in the contaminated zone and in uncontaminated background zones. The boundary zone was a former contaminated area where BTX were no longer detected. Denaturing gradient gel electrophoresis (DGGE) analysis of polymerase chain reaction (PCR)-amplified bacterial 16S rRNA gene fragments revealed that DGGE profiles for groundwater samples obtained from the contaminated zone were clustered together and distinct from those from uncontaminated zones. In addition, unique bacterial rRNA types were observed in the boundary zone. These results indicate that the boundary zone in the contaminant plumes served as a natural barrier for preventing the BTX contamination from spreading out. PMID:16957896

Takahata, Yoh; Kasai, Yuki; Hoaki, Toshihiro; Watanabe, Kazuya

2006-12-01

64

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

65

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

66

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...

67

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

68

Rapid intrinsic biodegradation of benzene, toluene, and xylenes at the boundary of a gasoline-contaminated plume under natural attenuation  

Microsoft Academic Search

A groundwater plume contaminated with gasoline constituents [mainly benzene, toluene, and xylenes (BTX)] had been treated by pumping and aeration for approximately 10 years, and the treatment strategy was recently changed to monitored natural attenuation (MNA). To gain information on the feasibility of using MNA to control the spread of BTX, chemical and microbiological parameters in groundwater samples obtained inside and

Yoh Takahata; Yuki Kasai; Toshihiro Hoaki; Kazuya Watanabe

2006-01-01

69

Impact of DNAPL Storage in Cracked Low Permeability Layers on Dissolved Contaminant Plume Persistence  

NASA Astrophysics Data System (ADS)

The subsurface storage and transport of a Dense Non-Aqueous Phase Liquid (DNAPL) was evaluated using a numerical model. DNAPLs are organic liquids comprised of slightly water-soluble chemicals or chemical mixtures that have a density greater than water. DNAPLs may pool atop low permeability layers upon entering the subsurface. Even with the removal or destruction of most pooled DNAPL mass, small amounts of the remaining contaminant, which had been transported into the low permeability layer, can dissolve into flowing groundwater and continue to act as a contamination source for decades. Recently developed models assume that transport in the low permeability zones is strictly diffusive; however field observations suggest that more mass is stored in the low permeability zones than can be explained by diffusion alone. Observations and experimental evidence indicate that cracks in low permeability layers may have apertures of sufficient size to allow entry of separate phase DNAPL. In this study, a numerical flow and transport model is employed using a dual domain construct (high and low permeability layers) to investigate the impact of DNAPL entry into cracked low permeability zones on dissolved contaminant plume evolution and persistence. This study found that DNAPL within cracks can significantly contribute to down gradient dissolved phase concentrations; however, the extent of this contribution is very dependent upon the rate of DNAPL dissolution. Given these findings, remediation goals may be difficult to meet if source remediation strategies are used which do not account for the effect of cracking upon contaminant transport and storage in low permeability layers.

Goltz, M. N.; Sievers, K. W.; Huang, J.; Demond, A. H.

2012-12-01

70

Biodegradation processes in a laboratory-scale groundwater contaminant plume assessed by fluorescence imaging and microbial analysis.  

PubMed

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

2007-06-01

71

Plume-Scale Testing of a Simplified Method for Detecting Tritium Contamination in Plants and Soil  

NASA Astrophysics Data System (ADS)

Research at the Amargosa Desert Research Site near Beatty, Nevada indicates that tritium movement from a closed low-level radioactive waste facility occurs primarily in the gas phase with preferential transport through coarse-textured sediment layers. However, models for movement of tritiated water vapor at the site fail to predict the extent of transport indicated by field measurements. In order to develop a better understanding of the spatial distribution of tritium contamination in the near-surface environment adjacent to the waste facility, a recently published tritium contamination-detection method was tested for collection and analysis of plume-scale data. The method entails solar distillation of plant water from foliage, followed by filtration and adsorption of scintillation-interfering constituents on a graphite-based solid-phase-extraction column prior to direct-scintillation counting. Samples were collected from 103 plants (creosote bush; Larrea tridentata) within a 72-ha area adjacent to the waste facility. Plant data showed elevated tritium concentrations up to 300 m from the waste facility. For a small ( ˜ 8 ha) area where high-density soil-water vapor data were already available, plant-based and soil-based concentration contours compared favorably. Plant data for previously unmeasured areas identified "hot spots" that were later verified by direct soil measurements. Regression analysis of tritium concentrations from collocated plant- and soil-sampling sites showed that empirical relations could be developed to predict soil concentrations (y) from the more simply determined plant concentrations (x): e.g., the equation for root-zone soil concentrations (Bq/L) was y = 1.156 x + 55.17 (r2 = 0.9521; SEE = 250). Results of this work have improved knowledge of the extent of tritium contamination in the near-surface environment. The pattern of the tritium concentrations indicated that the observed contamination originates from two sources--the waste-burial trenches and surface spills inside the waste facility. A study is now underway to estimate the flux of tritium from the subsurface to the atmosphere. The approach includes a combination of (i) periodic measurement of tritium concentrations in soil, plants, and air at selected sites, (ii) mapped tritium distributions, and (iii) continuous measurement of evapotranspiration.

Andraski, B. J.; Halford, K. J.; Johnson, M. J.; Michel, R. L.; Radyk, J. C.

2003-12-01

72

Insights into the dynamics and timing of crustal contamination of Kerguelen plume magmas using "Crystal Stratigraphy".  

NASA Astrophysics Data System (ADS)

Basalts represented by the 123-130 Ma Bunbury basalt (BB) Casuarina flow (BB), SW Australia, and drill core from the 107-108 Ma ODP Leg 183 Site 1137 (Elan Bank or EB) are purported to be products of the Kerguelen plume. Whole-rock geochemical data indicate these basalts have assimilated continental crust (Frey et al., 1996, EPSL 144:163; Ingle et al., 2002, EPSL 197:35) and combined, these 2 sites represent ˜22 m.y. of plume-crust interactions. In this study we use the crystal stratigraphy of (up to 1 cm) plagioclase phenocrysts in basalts from BB and EB to determine magmatic evolution (cf. Davidson et al., 1998, EOS 77:185). Core-to-rim trace element abundances were measured by LA-ICP-MS, major elements by EPMA, and 87Sr/86Sr compositions were determined by multicollector ICP-MS after computer-controlled microdrilling of discrete zones within each crystal. The BB plagioclase has overall lower Sr, Ba, REE, Ti and Ga abundances than the EB sample. Isotopically, the BB plagioclase contains a less radiogenic I(Sr) core (0.70414) and a more radiogenic rim composition (0.70567). The BB plagioclase exhibits core to rim Ce, Ti, Nd, and Ba enrichments that exceed those expected by fractional crystallization for the observed core-to-rim decrease in An content (66 to 60). It contains several resorption features defined by inclusion-rich zones mirroring crystal shape and a marked decrease in Sr and Ba abundances. Progressive core-to-rim enrichments in major and trace element (An, Sr, Ba, Ce, and Ti) abundances, as well as I(Sr), cut by relatively depleted Sr and Ba zones suggest initial growth in a relatively uncontaminated magma, progressive crustal assimilation, with periodic magma recharge. While a core I(Sr) value has not yet been determined, the EB plagioclase contains a less radiogenic rim (0.70618) relative to an intermediate zone (0.70645), which is adjacent to a resorption surface and also contains relatively enriched abundances of Sr, REE, and Ba. EB plagioclase trace element abundances suggest it initially grew in a highly crustal contaminated magma. The three distinct resorption surfaces observed in the EB plagioclase correspond to increased trace element abundances. We suggest the EB plagioclase initially grew in a highly contaminated magma where mixing with a highly REE enriched and radiogenic Sr end member occurred. Frey et al. (1996, EPSL 144:163) reported I(Sr) isotope ratios of Bunbury Casuarina basalts ranging from 0.70411-0.70534, less radiogenic than our rim I(Sr) value of 0.70567. Ingle et al. (2002, EPSL 197:35) reported I(Sr) isotope ratios for Elan Bank basalts ranging 0.70563-0.70573, again less radiogenic than our two I(Sr) measurements of 0.70618 and 0.70645. Disequilibrium exists between the plagioclase phenocrysts and the whole rock. We attribute the less radiogenic Sr signatures of whole rock samples relative to rims of their respective plagioclase phenocrysts to a large influx of parental plume melt just prior to eruption.

Kinman, W. S.; Neal, C. R.; Jon, D. P.

2003-12-01

73

A PCE groundwater plume discharging to a river: influence of the streambed and near-river zone on contaminant distributions.  

PubMed

An investigation of a tetrachloroethene (PCE) groundwater plume originating at a dry cleaning facility on a sand aquifer and discharging to a river showed that the near-river zone strongly modified the distribution, concentration, and composition of the plume prior to discharging into the surface water. The plume, streambed concentration, and hydrogeology were extensively characterized using the Waterloo profiler, mini-profiler, conventional and driveable multilevel samplers (MLS), Ground Penetrating Radar (GPR) surveys, streambed temperature mapping (to identify discharge zones), drivepoint piezometers, and soil coring and testing. The plume observed in the shallow streambed deposits was significantly different from what would have been predicted based on the characteristics of the upgradient plume. Spatial and temporal variations in the plume entering the near-river zone contributed to the complex contaminant distribution observed in the streambed where concentrations varied by factors of 100 to 5000 over lateral distances of less than 1 to 3.5 m. Low hydraulic conductivity semi-confining deposits and geological heterogeneities at depth below the streambed controlled the pattern of groundwater discharge through the streambed and influenced where the plume discharged into the river (even causing the plume to spread out over the full width of the streambed at some locations). The most important effect of the near-river zone on the plume was the extensive anaerobic biodegradation that occurred in the top 2.5 m of the streambed, even though essentially no biodegradation of the PCE plume was observed in the upgradient aquifer. Approximately 54% of the area of the plume in the streambed consisted solely of PCE transformation products, primarily cis-1,2-dichloroethene (cDCE) and vinyl chloride (VC). High concentrations in the interstitial water of the streambed did not correspond to high groundwater-discharge zones, but instead occurred in low discharge zones and are likely sorbed or retarded remnants of past high-concentration plume discharges. The high-concentration areas (up to 5529 microg/l of total volatile organics) in the streambed are of ecological concern and represent potential adverse exposure locations for benthic and hyporheic zone aquatic life, but the effect of these exposures on the overall health of the river has yet to be determined. Even if the upgradient source of PCE is remediated and additional PCE is prevented from reaching the streambed, the high-concentration deposits in the streambed will likely take decades to hundreds of years to flush completely clean under natural conditions because these areas have low vertical groundwater flow velocities and high retardation factors. Despite high concentrations of contaminants in the streambed, PCE was detected in the surface water only rarely due to rapid dilution in the river and no cDCE or VC was detected. Neither the sampling of surface water nor the sampling of the groundwater from the aquifer immediately adjacent to the river gave an accurate indication of the high concentrations of PCE biodegradation products present in the streambed. Sampling of the interstitial water of the shallow streambed deposits is necessary to accurately characterize the nature of plumes discharging to rivers. PMID:15336797

Conant, Brewster; Cherry, John A; Gillham, Robert W

2004-09-01

74

Long-term electrical resistivity monitoring of recharge-induced contaminant plume behavior.  

PubMed

Geophysical measurements, and electrical resistivity tomography (ERT) data in particular, are sensitive to properties that are related (directly or indirectly) to hydrological processes. The challenge is in extracting information from geophysical data at a relevant scale that can be used to gain insight about subsurface behavior and to parameterize or validate flow and transport models. Here, we consider the use of ERT data for examining the impact of recharge on subsurface contamination at the S-3 ponds of the Oak Ridge Integrated Field Research Challenge (IFRC) site in Tennessee. A large dataset of time-lapse cross-well and surface ERT data, collected at the site over a period of 12 months, is used to study time variations in resistivity due to changes in total dissolved solids (primarily nitrate). The electrical resistivity distributions recovered from cross-well and surface ERT data agrees well, and both of these datasets can be used to interpret spatiotemporal variations in subsurface nitrate concentrations due to rainfall, although the sensitivity of the electrical resistivity response to dilution varies with nitrate concentration. Using the time-lapse surface ERT data interpreted in terms of nitrate concentrations, we find that the subsurface nitrate concentration at this site varies as a function of spatial position, episodic heavy rainstorms (versus seasonal and annual fluctuations), and antecedent rainfall history. These results suggest that the surface ERT monitoring approach is potentially useful for examining subsurface plume responses to recharge over field-relevant scales. PMID:23103519

Gasperikova, Erika; Hubbard, Susan S; Watson, David B; Baker, Gregory S; Peterson, John E; Kowalsky, Michael B; Smith, Meagan; Brooks, Scott

2012-11-01

75

3-D Spectral Induced Polarization (IP) Imaging: Non-Invasive Characterization of Contaminant Plumes. Annual Progress Report for Period September 15, 1996-September 14, 1997.  

National Technical Information Service (NTIS)

The objective of this project is to develop the scientific basis for characterizing contaminant plumes in the earths subsurface using field measurements of induced polarization (IP) effects. Our first-year accomplishments are (1) laboratory experiments on...

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

1997-01-01

76

Assessing the Impact of Source-Zone Remediation Efforts at the Contaminant-Plume Scale Through Analysis of Contaminant Mass Discharge  

PubMed Central

The long-term impact of source-zone remediation efforts was assessed for a large site contaminated by trichloroethene. The impact of the remediation efforts (soil vapor extraction and in-situ chemical oxidation) was assessed through analysis of plume-scale contaminant mass discharge, which was measured using a high-resolution data set obtained from 23 years of operation of a large pump-and-treat system. The initial contaminant mass discharge peaked at approximately 7 kg/d, and then declined to approximately 2 kg/d. This latter value was sustained for several years prior to the initiation of source-zone remediation efforts. The contaminant mass discharge in 2010, measured several years after completion of the two source-zone remediation actions, was approximately 0.2 kg/d, which is ten times lower than the value prior to source-zone remediation. The time-continuous contaminant mass discharge data can be used to evaluate the impact of the source-zone remediation efforts on reducing the time required to operate the pump-and-treat system, and to estimate the cost savings associated with the decreased operational period. While significant reductions have been achieved, it is evident that the remediation efforts have not completely eliminated contaminant mass discharge and associated risk. Remaining contaminant mass contributing to the current mass discharge is hypothesized to comprise poorly-accessible mass in the source zones, as well as aqueous (and sorbed) mass present in the extensive lower-permeability units located within and adjacent to the contaminant plume. The fate of these sources is an issue of critical import to the remediation of chlorinated-solvent contaminated sites, and development of methods to address these sources will be required to achieve successful long-term management of such sites and to ultimately transition them to closure.

Brusseau, M. L.; Hatton, J.; DiGuiseppi, W.

2011-01-01

77

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

SciTech Connect

Natural attenuation of TCE under aerobic conditions at the INEEL Test Area North site was demonstrated largely on the basis of preferential loss of TCE relative to conservative solutes (PCE and H-3) along groundwater flow paths. First order degradation half-lives were calculated from the rate of preferential TCE loss. We are utilizing the same approach at other DOE sites that have aerobic TCE plumes to determine if aerobic natural attenuation of TCE is rapid enough at these sites to be environmentally significant, i.e. if natural attenuation can reduce concentrations to acceptable levels before groundwater reaches potential receptors. The first step in this process was to identify TCE plumes at DOE sites that have the appropriate site conditions and data needed to perform this analysis. The site conditions include the presence of TCE in groundwater at appreciable concentrations in an aerobic aquifer, a co-mingled contaminant that can be used as a conservative tracer (e.g. PCE, H-3, Tc-99), a flow path that represents at least a decade of travel time, and several monitoring wells located along this flow path. Candidate sites were identified through interviews with knowledgeable individuals in the DOE system and by screening the U.S. Dept. of Energy Groundwater Database using the keywords ''TCE'' and ''groundwater''. The initial screening yielded 25 plumes for consideration. These sites had anywhere from one to 37 individual plumes containing TCE. Of the 25 sites, 13 sites were further evaluated because they met the screening criteria or were promising. After contacting DOE personnel from the respective sites, they were divided into three groups: (1) sites that meet all the project criteria, (2) sites that could potentially be used for the project, and (3) DOE sites that did not meet the criteria. The five sites with plumes that met the criteria were: Brookhaven National Laboratory, Lawrence Livermore National Laboratory, Paducah Gaseous Diffusion Plant, Rocky Flats Environmental Technology Site, and the Savannah River Site. Detailed characterization data from the promising plumes is being entered into our database as it is received. The next step is to calculate natural attenuation half-life values for all of these plumes. We will next identify the plumes in which natural attenuation via aerobic degradation of TCE is fast enough that it may be relevant as a component of a remedy. We will then select at least one of these sites and either modify an existing groundwater transport model or, if necessary, create a new model, for this plume. This model will initially include first order decay of TCE, and degradation will be parameterized using the half-live values determined from the field data. The models will be used to simulate the evolution of the TCE plume and to predict concentrations as a function of time at property lines or other artificial boundaries, and where potential receptors are located. Ultimately rate data from th e laboratory studies being performed at INEEL will be incorporated into this model, as well as the model of the TAN site to provide a realistic prediction of degradation rates and plume longevity. Although identifying suitable TCE plumes and obtaining characterization data has taken longer than expected, this process has successfully identified the plumes needed for the detailed modeling activity without adversely impacting the project budget.

Sorenson, Kent S. Jr.

2003-06-01

78

Changes in concentrations of a TCE plume in near- stream zones of a DNAPL contaminated area adjacent to a stream  

NASA Astrophysics Data System (ADS)

A field investigation of a trichloroethylene (TCE) groundwater plume originating at an industrial complex and its discharges to a stream nearby showed that apparent plume attenuation occurred in the near-stream zone of a DNAPL contaminated area adjacent to a stream prior to discharging to the stream. The concentrations of TCE and cis-1,2-dichloroethene (cis-DCE) in groundwater, hyporheic water, stream water and streambed, and hydrogeology were characterized using mini-piezometers, monitoring wells, Ground Penetrating Radar (GPR) surveys, and soil coring. In the near stream zones temporal and spatial TCE plume concentration changes and mass fluxes were investigated along the flowpath of groundwater discharging to the stream. It is evident that observed concentrations of contaminants (TCE and cis-DCE) were reduced in the near-stream zone, resulting that TCE and cis-DCE were not detected in the streambed and stream water. Ground GPR surveys done in the near stream zone found that wire and water treatment pipe conduits were buried under the ground next to the stream, which could lead groundwater flow field distortion in this zone. At streambed, the GPR survey and soil coring indicated the presence of low permeable zones consisting of rotten material deposits at the top of 0.3 m ~ 0.8 m underlain by silty sands. These hydrogeological features can also attribute to no detection of contaminants in the streambed and stream water because low permeable zone is an obstacle to effective interactions between groundwater and stream water. More investigations will be carried out for comprehensive understanding of hydrological and biogeochemical processes associated with TCE plume attenuation in near stream zones and streambed in the site.

Lee, S.; Hyun, Y.; Lee, K.

2012-12-01

79

Effects of Adsorption Constant Uncertainty on Contaminant Plume Migration: One and Two Dimensional Numerical Studies  

NASA Astrophysics Data System (ADS)

In this study, we use one- and two-dimensional (1D and 2D) reactive-transport models to numerically examine variations in predictions due to uncertainty in the adsorption constants. The study specifically focuses on the hydrogeology and mineralogy of the Naturita uranium mill tailings site in Colorado. This work demonstrates the importance of selecting the appropriate adsorption constants when using reactive-transport models to evaluate risk and pollution attenuation at contaminated sites. In our model, uranium is removed from mill tailings leachate through adsorption onto smectite, an abundant clay mineral at the Naturita site. Uranium adsorbs to specific surface sites on both the basal planes and edges of the smectite. Because uranium adsorbs predominantly to the aluminum edge surface sites [>(e)AlOH], we chose to examine uncertainty only in the equilibrium constants associated with these sites. Using the Latin Hypercube Sampling method, one-hundred pairs of adsorption constant (log K) values are selected for the surface species >(e)AlO- and >(e)AlOUO2+, from normal distributions of each log K. Following a grid convergence study, 1D simulation results can be identified by two distinct groups of uranium breakthrough curves. In the first group, the breakthrough curves exhibit a classical sigmoidal shape whereas in the second group the breakthrough curves display higher uranium concentrations in solution over greater distances and times. These two groups are clearly separated by two different ranges of log K >(e)AlO- values or two different ranges for the smectite point of zero charge. Preliminary 2D simulations, in both homogeneous and randomly heterogeneous aquifers demonstrate that plume geometry and migration in longitudinal and transverse directions are also influenced by the choice of adsorption constants.

Eliassi, M.

2002-12-01

80

Migration of a groundwater contaminant plume by stratabound flow in Waste Area Grouping 1 at Oak Ridge National Laboratory, Oak Ridge, Tennessee. Environmental Restoration Program  

SciTech Connect

The discovery of radiologically contaminated groundwater in core hole CH-8 in the western portion of Waste Area Grouping (WAG) 1 at Oak Ridge National Laboratory (ORNL) prompted a detailed investigation to identify the contaminant plume. Utilizing a working hypothesis of stratabound groundwater flow and contaminant transport, investigators analyzed existing subsurface geologic data to predict the contaminant plume discharge location in first Creek and locations of contaminated groundwater seepage into storm drains. The hypothesis states that differential lithologic/fracture conditions lead to the development of preferred flow and transport pathways, of discrete vertical extent, which may not be coincident with the hydraulic gradient. Leakage out of the stratabound pathway is a minor component of the overall plume configuration.

Ketelle, R.H.; Lee, R.R.

1992-08-01

81

Migration of a groundwater contaminant plume by stratabound flow in Waste Area Grouping 1 at Oak Ridge National Laboratory, Oak Ridge, Tennessee  

SciTech Connect

The discovery of radiologically contaminated groundwater in core hole CH-8 in the western portion of Waste Area Grouping (WAG) 1 at Oak Ridge National Laboratory (ORNL) prompted a detailed investigation to identify the contaminant plume. Utilizing a working hypothesis of stratabound groundwater flow and contaminant transport, investigators analyzed existing subsurface geologic data to predict the contaminant plume discharge location in first Creek and locations of contaminated groundwater seepage into storm drains. The hypothesis states that differential lithologic/fracture conditions lead to the development of preferred flow and transport pathways, of discrete vertical extent, which may not be coincident with the hydraulic gradient. Leakage out of the stratabound pathway is a minor component of the overall plume configuration.

Ketelle, R.H.; Lee, R.R.

1992-08-01

82

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

83

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

84

Superfund record of decision (EPA Region 9): Newmark Groundwater Contamination Superfund Site, Muscoy Plume Operable Unit, San Bernardino, CA, March 24, 1995  

SciTech Connect

The decision document presents the selected remedial action for the Muscoy Plume Operable Unit, Newmark Groundwater Contamination Superfund site. The Muscoy Plume OU is an interim action focusing on contamination in the underground water supply in the Bunker Hill Basin of San Bernardino, west of the Shandin Hills. The remedy involves groundwater extraction (pumping) and treatment of 6,200 gallons per minute (gpm) in San Bernardino at the leading edge of the contaminant plume. All the extracted contaminated groundwater shall be treated to remove Volatile Organic Compounds (VOCs) by either of two proven treatment technologies: granular activated carbon (GAC) filtration or air stripping. The treated water will be transferred to a public water supply agency for distribution. Groundwater monitoring wells will be installed and sampled regularly to help evaluate the effectiveness of the remedy.

NONE

1995-06-01

85

Uncertainty based optimal monitoring network design for a chlorinated hydrocarbon contaminated site  

Microsoft Academic Search

An application of a newly developed optimal monitoring network for the delineation of contaminants in groundwater is demonstrated\\u000a in this study. Designing a monitoring network in an optimal manner helps to delineate the contaminant plume with a minimum\\u000a number of monitoring wells at optimal locations at a contaminated site. The basic principle used in this study is that the\\u000a wells

Sreenivasulu Chadalavada; Bithin Datta; Ravi Naidu

2011-01-01

86

Biopropellant Engine Plume Contamination Program. Volume I. Chamber Measurements. Phase I.  

National Technical Information Service (NTIS)

An experimental program to measure the mass flux in the backflow region of a 5-lbf bipropellant thruster at angles up to 147 deg with respect to the plume centerline using temperature-controlled and temperature-compensated quartz crystal microbalances (QC...

R. E. Alt J. A. Roux B. E. Wood D. F. Frazine R. Dawbarn

1979-01-01

87

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

88

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

89

Ground water contaminant source and transport parameter identification by correlation coefficient optimization  

SciTech Connect

The initial step in a ground water contamination remediation process is to identify the extent of the plume. One way to optimize well deployment is to solve an inverse contaminant transport problem. Inverse procedures bas4ed on correlation coefficient optimization are developed to locate ground water contaminant sources and to identify transport parameters. For cases involving two-dimensional instantaneous and continuous sources, the inverse formulas are explicit. These procedures allow not only for the delineation of the sampled contaminant plume, but also the tracing and the projection of the plume history.

Sidauruk, P.; Cheng, A.H.D. [Univ. of Delaware, Newark, DE (United States). Dept. of Civil and Environmental Engineering; Ouazar, D. [Univ. Mohammed 5, Rabat (Morocco). Ecole Mohammadia d`Ingenieurs

1998-03-01

90

Huntington beach shoreline contamination investigation, phase III: coastal circulation and transport patterns : the likelihood of OCSD's plume impacting Huntington beach shoreline  

USGS Publications Warehouse

A consortium of agencies have conducted an extensive investigation of the coastal ocean circulation and transport pathways off Huntington Beach, with the aim of identifying any causal links that may exist between the offshore discharge of wastewater by OCSD and the significant bacterial contamination observed along the Huntington Beach shoreline. This is the third study supported by OCSD to determine possible land-based and coa Although the study identifies several possible coastal ocean pathways by which diluted wastewater may be transported to the beach, including internal tide, sea-breeze and subtidal flow features, there were no direct observations of either the high bacteria concentrations seen in the OCSD plume at the shelf break reaching the shoreline in significant levels or of an association between the existence of a coastal ocean process and beach contamination at or above AB411 levels. It is concluded that the OCSD plume is not a major cause of beach contamination; no causal links could be demonstrated. This conclusion is based on the absence of direct observation of plume-beach links, on analysis of the spatial and temporal patterns of shoreline contamination and coastal ocean processes, and on the observation of higher levels of contamination at the beach than in the plume.

Noble, Marlene; Xu, Jingping; Rosenfeld, Leslie; Largier, John; Hamilton, Peter; Jones, Burt; Robertson, George

2003-01-01

91

Application of satellite infrared data for mapping of thermal plume contamination in coastal ecosystem of Korea.  

PubMed

The 5900 MW Younggwang nuclear power station on the west coast of Korea discharges warm water affecting coastal ecology [KORDI report (2003). Wide area observation of the impact of the operation of Younggwang nuclear power plant 5 and 6, No. BSPI 319-00-1426-3, KORDI, Seoul, Korea]. Here the spatial and temporal characteristics of the thermal plume signature of warm water are reported from a time series (1985-2003) of space-borne, thermal infrared data from Landsat and National Oceanic and Atmospheric Administration (NOAA) satellites. Sea surface temperature (SST) were characterized using advanced very high resolution radiometer data from the NOAA satellites. These data demonstrated the general pattern and extension of the thermal plume signature in the Younggwang coastal areas. In contrast, the analysis of SST from thematic mapper data using the Landsat-5 and 7 satellites provided enhanced information about the plume shape, dimension and direction of dispersion in these waters. The thermal plume signature was detected from 70 to 100 km to the south of the discharge during the summer monsoon and 50 to 70 km to the northwest during the winter monsoon. The mean detected plume temperature was 28 degrees C in summer and 12 degrees C in winter. The DeltaT varied from 2 to 4 degrees C in winter and 2 degrees C in summer. These values are lower than the re-circulating water temperature (6-9 degrees C). In addition the temperature difference between tidal flats and offshore (SSTtidal flats - SSToffsore) was found to vary from 5.4 to 8.5 degrees C during the flood tides and 3.5 degrees C during the ebb tide. The data also suggest that water heated by direct solar radiation on the tidal flats during the flood tides might have been transported offshore during the ebb tide. Based on these results we suggest that there is an urgent need to protect the health of Younggwang coastal marine ecosystem from the severe thermal impact by the large quantity of warm water discharged from the Younggwang nuclear power plant. PMID:16256190

Ahn, Yu-Hwan; Shanmugam, Palanisamy; Lee, Jae-Hak; Kang, Yong Q

2006-03-01

92

Delineation of a landfill leachate plume and flow channels in coastal sands near Christchurch, New Zealand, using a shallow electromagnetic survey method  

Microsoft Academic Search

The Burwood landfill, which serves the city of Christchurch, New Zealand, is situated on coastal sands underlain by a sequence of aquifers and aquitards. Groundwater flow is toward the coast, located approximately 700m from the landfill boundary. Shortly after completion of the first phase of the landfill, an array of wells was installed to detect any contaminant from the landfill.

David C. Nobes; Mark J. Armstrong; Murray E. Close

2000-01-01

93

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

94

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  

Microsoft Academic Search

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

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

1997-01-01

95

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...

96

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

97

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

SciTech Connect

Dissolved dense nonaqueous-phase liquid plumes are persistent, widespread problems in the DOE complex. At the Idaho National Engineering and Environmental Laboratory, dissolved trichloroethylene (TCE) is disappearing from the Snake River Plain aquifer (SRPA) by natural attenuation, a finding that saves significant site restoration costs. Acceptance of monitored natural attenuation as a preferred treatment technology requires direct evidence of the processes and rates of the degradation. Our proposal aims to provide that evidence for one such site by testing two hypotheses. First, we believe that realistic values for in situ rates of TCE cometabolism can be obtained by sustaining the putative microorganisms at the low catabolic activities consistent with aquifer conditions. Second, the patterns of functional gene expression evident in these communities under starvation conditions while carrying out TCE cometabolism can be used to diagnose the cometabolic activity in the aquifer itself. Using the cometabolism rate parameters derived in low-growth bioreactors, we will complete the models that predict the time until background levels of TCE are attained at this location and validate the long-term stewardship of this plume. Realistic terms for cometabolism of TCE will provide marked improvements in DOE's ability to predict and monitor natural attenuation of chlorinated organics at other sites, increase the acceptability of this solution, and provide significant economic and health benefits through this noninvasive remediation strategy. Finally, this project 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.

2005-06-01

98

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

99

Plume Busters  

NSDL National Science Digital Library

Environmental and earth science students seldom have an opportunity to apply what they learn in class to the solution of real-world problems. With NSF support we have developed the prototype Plume Busters software, in which students take on the role of an environmental consultant. Following a pipeline spill, the environmental consultant is hired by the pipeline owner to locate the resulting plume created by the spill and remediate the contaminated aquifer at minimum monetary and time cost. The contamination must be removed from the aquifer before it reaches the river and eventually a downstream public water supply. The software consists of an interactive Java application and accompanying HTML linked pages. The application simulates movement of a plume from a pipeline break through a shallow alluvial aquifer towards the river. The accompanying web pages establish the simulated contamination scenario and provide students with background material on ground-water flow and transport principles. To make the role-play more realistic, the student must consider cost and time when making decisions about siting observation wells and wells for the pump-and-treat remediation system.

Macfarlane, Allen

100

The role of diffusion in compound-specific transverse dispersion and mixing-controlled degradation of contaminant plumes  

NASA Astrophysics Data System (ADS)

Transverse dispersion is relevant for lateral spreading of compounds in water-saturated porous media as well as for mixing of reactants. In groundwater solute transport, complete mixing at the pore scale by diffusion is traditionally assumed. This assumption leads to parameterizations of transverse dispersion coefficients linearly increasing with the average flow velocity. In chemical engineering, typically, nonlinear relationships are used, however, at much higher Péclet numbers. New data from high resolution multi-tracer 2D tank experiments show that dispersion coefficients are compound specific in all flow regimes. Pore-scale simulations allowed us to point out that the interplay between advective and diffusive mass transfer processes at the microscopic scale results in vertical concentration gradients leading to a different degree of incomplete mixing of the considered tracers in the pore channels. These experimental and modeling findings lead to a non-linear, compound-specific macroscopic parameterization of transverse dispersion coefficients and have significant implications in modeling reactive transport in groundwater, in estimating the length of contaminant plumes as well as in the interpretation of experimental data and isotopic signatures.

Grathwohl, P.; Chiogna, G.; Rolle, M.

2011-12-01

101

Detection of fresh ground water and a contaminant plume beneath Red Brook Harbor, Cape Cod, Massachusetts, 2000  

USGS Publications Warehouse

Trichloroethene and tetrachloroethene were detected in ground water in a vertical interval from about 68 to 176 feet below sea level beneath the shoreline where the contaminant plume emanating from a capped landfill on the Massachusetts Military Reservation intersects Red Brook Harbor. The highest concentrations at the shoreline, about 15 micrograms per liter of trichloroethene and 1 microgram per liter of tetrachloroethene, were measured in samples from one well at about 176 feet below sea level. The concentrations of nutrients, such as nitrate and ammonium, and trace metals, such as iron and manganese, in these same samples are typical of uncontaminated ground water on Cape Cod. Fresh ground water (bulk electrical conductance less than 100 millisiemens per meter) is present beneath the harbor at 40 of 48 locations investigated within about 250 feet of the shoreline. Fresh ground water also was detected at one location approximately 450 feet from shore. The harbor bottom consists of soft sediments that range in thickness from 0 to greater than 20 feet and overlie sandy aquifer materials. Trichloroethene was detected at several locations in fresh ground water from the sandy aquifer materials beneath the harbor. The highest trichloroethene concentration, about 4.5 micrograms per liter, was measured about 450 feet from shore.

McCobb, Timothy D.; LeBlanc, Denis R.

2002-01-01

102

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

103

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

104

Determination of Premining Geochemical Background and Delineation of Extent of Sediment Contamination in Blue Creek Downstream from Midnite Mine, Stevens County, Washington  

USGS Publications Warehouse

Geochemical and radionuclide studies of sediment recovered from eight core sites in the Blue Creek flood plain and Blue Creek delta downstream in Lake Roosevelt provided a stratigraphic geochemical record of the contamination from uranium mining at the Midnite Mine. Sediment recovered from cores in a wetland immediately downstream from the mine site as well as from sediment catchments in Blue Creek and from cores in the delta in Blue Creek cove provided sufficient data to determine the premining geochemical background for the Midnite Mine tributary drainage. These data provide a geochemical background that includes material eroded from the Midnite Mine site prior to mine development. Premining geochemical background for the Blue Creek basin has also been determined using stream-sediment samples from parts of the Blue Creek, Oyachen Creek, and Sand Creek drainage basins not immediately impacted by mining. Sediment geochemistry showed that premining uranium concentrations in the Midnite Mine tributary immediately downstream of the mine site were strongly elevated relative to the crustal abundance of uranium (2.3 ppm). Cesium-137 (137Cs) data and public records of production at the Midnite Mine site provided age control to document timelines in the sediment from the core immediately downstream from the mine site. Mining at the Midnite Mine site on the Spokane Indian Reservation between 1956 and 1981 resulted in production of more than 10 million pounds of U3O8. Contamination of the sediment by uranium during the mining period is documented from the Midnite Mine along a small tributary to the confluence of Blue Creek, in Blue Creek, and into the Blue Creek delta. During the period of active mining (1956?1981), enrichment of base metals in the sediment of Blue Creek delta was elevated by as much as 4 times the concentration of those same metals prior to mining. Cadmium concentrations were elevated by a factor of 10 and uranium by factors of 16 to 55 times premining geochemical background determined upstream of the mine site. Postmining metal concentrations in sediment are lower than during the mining period, but remain elevated relative to premining geochemical background. Furthermore, the sediment composition of surface sediment in the Blue Creek delta is contaminated. Base-metal contamination by arsenic, cadmium, lead, and zinc in sediment in the delta in Blue Creek cove is dominated by suspended sediment from the Coeur d?Alene mining district. Uranium contamination in surface sediment in the delta of Blue Creek cove extends at least 500 meters downstream from the mouth of Blue Creek as defined by the 1,290-ft elevation boundary between lands administered by the National Park Service and the Spokane Indian Tribe. Comparisons of the premining geochemical background to sediment sampled during the period the mine was in operation, and to the sediment data from the postmining period, are used to delineate the extent of contaminated sediment in Blue Creek cove along the thalweg of Blue Creek into Lake Roosevelt. The extent of contamination out into Lake Roosevelt by mining remains open.

Church, Stanley E.; Kirschner, Frederick E.; Choate, LaDonna M.; Lamothe, Paul J.; Budahn, James R.; Brown, Zoe Ann

2008-01-01

105

A full-scale pilot study to investigate the remediation potential of air sparging through a horizontal well oriented perpendicular to a contaminant plume: Preliminary results  

SciTech Connect

A full-scale, one-year pilot study of a new design of air sparging system is being conducted at a site in the Midwest where plumes of TCE-contaminated ground water have been identified in an unconfined sand and gravel aquifer in which ground water flows at approximately 0.5 feet/day. TCE concentrations in the ground water range up to several thousand {micro}g/L. A horizontal sparging well and associated soil vapor extraction (SVE) system have been constructed perpendicular to a contaminant plume immediately downgradient from its source. In addition, a vertical sparging well and SVE system have been constructed at the source to accelerate volatilization of TCE from the soil and ground water in the area of greatest contamination. All 24 SVE wells installed for the study are vertical. Although sparging from horizontal wells has been shown to be effective at other sites, this pilot study represents the first time to the authors knowledge that a horizontal sparging well has been oriented perpendicular to the ground water flow direction in order to intercept a contaminant plume. In this design, the horizontal air sparging well takes advantage of the natural ground water flow to maximize its zone of influence. Preliminary data from a network of 24 ground water monitoring wells and 15 vadose zone monitoring wells show that for a given air sparing flow rate, the radius of influence (lateral distance air travels through the aquifer) of the horizontal well is significantly greater than the radius of influence of the vertical well, although both wells are screened in similar sediments at the same depth below the water table.

Wade, A.; Wallace, G.W.; Seigwald, S.F. [Woodward-Clyde Consultants, Overland Park, KS (United States)

1995-09-01

106

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

NASA Astrophysics Data System (ADS)

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.

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

2011-12-01

107

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

SciTech Connect

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.

Brusseau, M. L.; Carroll, Kenneth C.; Allen, Tim J.; Baker, Joseph R.; DiGuiseppi, W.; Hatton, J.; Morrison, C.; Russo, A.; Berkompas, J.

2011-05-26

108

Impact of in situ chemical oxidation on contaminant mass discharge: linking source-zone and plume-scale characterizations of remediation performance.  

PubMed

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

2011-06-15

109

Investigation of the Strontium-90 Contaminant Plume along the Shoreline of the Columbia River at the 100-N Area of the Hanford Site  

SciTech Connect

Efforts are underway to remediate strontium-laden groundwater to the Columbia River at the 100-N Area of the Hanford Site. Past practices of the 100-N reactor liquid waste disposal sites has left strontium-90 sorbed onto sediments which is a continuing source of contaminant discharge to the river. The Remediation Task of the Science and Technology Project assessed the interaction of groundwater and river water at the hyporheic zone. Limited data have been obtained at this interface of contaminant concentrations, geology, groundwater chemistry, affects of river stage and other variables that may affect strontium-90 release. Efforts were also undertaken to determine the extent, both laterally and horizontally, of the strontium-90 plume along the shoreline and to potentially find an alternative constituent to monitor strontium-90 that would be more cost effective and could possibly be done under real time conditions. A baseline of strontium-90 concentrations along the shoreline was developed to help assess remediation technologies.

Mendoza, Donaldo P.; Patton, Gregory W.; Hartman, Mary J.; Spane, Frank A.; Sweeney, Mark D.; Fritz, Brad G.; Gilmore, Tyler J.; Mackley, Rob D.; Bjornstad, Bruce N.; Clayton, Ray E.

2007-10-01

110

Experimental characterization of a plume of passive contaminant above a thermal source: capture efficiency of a fume extraction hood.  

PubMed

Industrial ventilation problems can be linked to the formation of thermal plumes that develop due to natural convection above various heat sources. These plumes, independent of the energy losses and thermal constraints caused, can also be the carrier of polluting products. This article describes an experimental study of the dynamic, thermal, and mass fields that develop from a hot rectangular (0.5 x 1.25 m) horizontal source. The metrology available allows the measurement of not only the local temperatures and velocities but also the concentration of a tracer gas (helium). Mathematical models have been developed enabling representation of the fields concerned; their characterization by isothermal, iso-velocity, or iso-concentration curves; calculation of the flow rate carried by the plume at a given height; calculation of the enthalpy transport; and so on. Moreover, a pollutant capture device has been introduced, and the measurement technique used allows the determination of various efficiencies of practical interest. The ratio of capture flow to free plume flow at a particular height appears to correlate well with the mean efficiencies obtained for distinct source temperatures. PMID:19666957

Devienne, René; Fontaine, Jean Raymond; Kicka, Jérémie; Bonthoux, Francis

2009-10-01

111

Geochemical Characteristics of the Contaminant Waste Plume in the F-Area of the Savannah River Site: From Kilometer to Micrometer Scales  

NASA Astrophysics Data System (ADS)

The Savannah River Site (SRS) was a major DOE facility for plutonium production during the Cold War. Low-level radioactivity acidic waste solutions were discharged to a series of unlined seepage basins in the F-Area of the SRS from 1955-1989. Although the site has gone through many years of active remediation, the groundwater remains acidic with pH values as low as 3.2, and the concentrations of U and other radionuclides are still up to ten times higher than their maximum contaminant levels (MCLs). In order to understand the current and predict the future contaminant behavior, a comprehensive investigation is being conducted, funded jointly by the DOE’s offices of Biological and Environmental Resources (BER) and Environmental Management (EM). Five boreholes were drilled outside and within the plume along the groundwater flow path. Samples were collected from varied depths of each borehole, sediment pore-waters were extracted by ultracentrifugation, and the solid phase and pore-water were characterized. We identified the sediment mineralogy as being composed predominantly fine quartz sand with 2 to 12% clay. Kaolinite and goethite are the major minerals of the clay-sized fraction, residing primarily as coatings of varied thicknesses on quartz sand grains, providing reactive surfaces for contaminant adsorption. The measured U “field” distribution coefficients (Kd) and U concentrations in the pore waters are strongly pH dependent. These results are consistent with laboratory equilibrium adsorption studies, where U adsorption onto SRS sediments increases sharply from pH 3 to 5, and reaches ?100% at pH 6-7. The variability in U adsorption capacity in these sediments is mainly caused by differences in goethite/clay content and effective reactive specific surface area. Measured “field” Kd values are smaller than those obtained from laboratory equilibrium adsorption studies with the same contaminated sediments. The equilibrium pH-dependent U adsorption experiments show the shift of adsorption edge to lower pH by about 1.0 unit for the plume sediment in comparison with pristine sediment. The long-term acid leaching might have modified the adsorption behavior of the sediments. The mechanisms underlying these characteristics will be discussed.

Dong, W.; Wan, J.; Denham, M.; Seaman, J. C.; Rakshit, S.; Tokunaga, T. K.; Spycher, N.; Hubbard, S. S.

2010-12-01

112

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

113

Lazy plumes  

Microsoft Academic Search

We examine the dynamics of turbulent lazy plumes rising from horizontal area sources and from vertically distributed line sources into a quiescent environment of uniform density. First, we consider plumes with internal buoyancy flux gain and, secondly, plumes from horizontal area sources that have significant momentum flux deficits. We re-cast the conservation equations of Morton et al. (1956) for a

G. R. Hunt; N. B. Kaye

2005-01-01

114

Design of optimal, reliable plume capture schemes: Application to the Gloucester landfill ground-water contamination problem  

Microsoft Academic Search

A ground-water quality management model is applied to the Gloucester Landfill site, located near Ottawa, Canada, to examine the effectiveness of various single-well pumping schemes for the capture of dissolved contaminants. Deterministic and stochastic design analyses are conducted through ground-water solute transport modeling of the site. The purpose of the modeling analysis is to develop contaminant capture designs that both

R. M. Gailey; S. M. Gorelick

2009-01-01

115

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

116

Evaluation of Visible Plumes.  

ERIC Educational Resources Information Center

Developed for presentation at the 12th Conference on Methods in Air Pollution and Industrial Hygiene Studies, University of Southern California, April, 1971, this outline discusses plumes with contaminants that are visible to the naked eye. Information covers: (1) history of air pollution control regulations, (2) need for methods of evaluating…

Brennan, Thomas

117

Comment on “Analysis of groundwater contamination using concentration-time series recorded during an integral pumping test: Bias introduced by strong concentration gradients within the plume” by Allelign Zeru and Gerhard Schäfer  

NASA Astrophysics Data System (ADS)

We consider the results of a recent paper in this journal [Zeru, A. and Schäfer, G., 2005. Analysis of groundwater contamination using concentration-time series recorded during an integral pumping test: Bias introduced by strong concentration gradients within the plume. Journal of Contaminant Hydrology 81 (2005) 106-124], which addresses the field-scale characterisation of contaminant plumes in groundwater. There, it is concluded that contaminant concentration gradients can bias Integral Pumping Test (IPT) interpretations considerably, in particular if IPTs are conducted in advective fronts of contaminant plumes. We discuss implications of this setting and also argue that the longitudinal and transverse dispersivities used in the examples of Zeru and Schäfer (2005) of up to 30 m and 3 m, respectively, are generally very high for the here relevant capture zone scale (< 20 m). However, regardless of both longitudinal and transverse concentration gradients, we further show through a counter-example that IPT results are unbiased as long as the concentration attenuation along the flow direction is linear over the capture zone extent.

Bayer-Raich, Martí; Jarsjö, Jerker; Teutsch, Georg

2007-03-01

118

Comment on "Analysis of groundwater contamination using concentration-time series recorded during an integral pumping test: Bias introduced by strong concentration gradients within the plume" by Allelign Zeru and Gerhard Schäfer.  

PubMed

We consider the results of a recent paper in this journal [Zeru, A. and Schäfer, G., 2005. Analysis of groundwater contamination using concentration-time series recorded during an integral pumping test: Bias introduced by strong concentration gradients within the plume. Journal of Contaminant Hydrology 81 (2005) 106-124], which addresses the field-scale characterisation of contaminant plumes in groundwater. There, it is concluded that contaminant concentration gradients can bias Integral Pumping Test (IPT) interpretations considerably, in particular if IPTs are conducted in advective fronts of contaminant plumes. We discuss implications of this setting and also argue that the longitudinal and transverse dispersivities used in the examples of Zeru and Schäfer (2005) of up to 30 m and 3 m, respectively, are generally very high for the here relevant capture zone scale (<20 m). However, regardless of both longitudinal and transverse concentration gradients, we further show through a counter-example that IPT results are unbiased as long as the concentration attenuation along the flow direction is linear over the capture zone extent. PMID:17123662

Bayer-Raich, Martí; Jarsjö, Jerker; Teutsch, Georg

2007-03-20

119

Petrology and geochemistry of crustally contaminated komatiitic basalts from the Vetreny Belt, southeastern Baltic Shield: Evidence for an early Proterozoic mantle plume beneath rifted Archean continental lithosphere  

NASA Astrophysics Data System (ADS)

New isotope and trace element data are presented for komatiitic basalts and a related peridotite Vinela Dike from the large Vetreny Belt in the southeastern Baltic Shield. The MgO contents of the erupted and intruded magmas are inferred to increase from 13 to 17% towards the center of the belt, which implies the respective increase in liquidus temperatures from 1370 to 1440°C. The elevated liquidus temperatures suggest that the source of the komatiite magmas had a substantially higher potential temperature (1630°C) than the ambient mantle (1480°C) and are regarded as evidence for the existence of a mantle plume underlying the region at ˜2.45 Ga. Parental magmas to the lavas and the Vinela Dike were shown to have komatiite composition and were derived from a long-term LREE-depleted mantle source with ?Nd( T) of ca. +2.6. The evolution of these magmas en route to the surface was mainly controlled by 4-15% contamination with older felsic crustal rocks, which resulted in substantial changes in incompatible trace element and isotope ratios. The obtained Sm?Nd internal isochron ages of 2449 ± 35 and 2410 ± 34 Ma for the lavas, 2430 ± 174 Ma for the Vinela Dike, and a whole-rock Pb?Pb age of 2424 ± 178 Ma for the lavas together with a U?Pb zircon age of 2437 ± 3 Ma are identical to the reported U?Pb zircon and baddeleyite ages for numerous mafic-ultramafic layered intrusions in central and northern Karelia. From their chemical and isotope similarities, it is likely that these rocks had allied parental magmas. These magmas may have been emplaced in a continental rift setting during the interaction of a mantle plume and continental crust. Impinging of a plume head beneath the continental lithosphere resulted in its thinning, stretching, and rifting but failed to open a new ocean. This extensive magmatic event was responsible for a substantial contribution of early Proterozoic juvenile material to the Archean continental crust in the Baltic Shield.

Puchtel, I. S.; Haase, K. M.; Hofmann, A. W.; Chauvel, C.; Kulikov, V. S.; Garbe-Schönberg, C.-D.; Nemchin, A. A.

1997-03-01

120

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...

121

A comparison of contaminant plume statistics from a Gaussian puff and urban CFD model for two large cities  

NASA Astrophysics Data System (ADS)

This paper quantitatively assesses the spatial extent of modeled contaminated regions resulting from hypothetical airborne agent releases in major urban areas. We compare statistics from a release at several different sites in Washington DC and Chicago using a Gaussian puff model (SCIPUFF, version 1.3, with urban parameter settings) and a building-resolving computational fluid dynamics (CFD) model (FAST3D-CT). For a neutrally buoyant gas source term with urban meteorology, we compare near-surface dosage values within several kilometers of the release during the first half hour, before the gas is dispersed beyond the critical lethal level. In particular, using "fine-grain" point-wise statistics such as fractional bias, spatial correlations and the percentage of points lying within a factor of two, we find that dosage distributions from the Gaussian puff and CFD model share few features in common. Yet the "coarse-grain" statistic that compares areas contained within a given contour level reveals that the differences between the models are less pronounced. Most significant among these distinctions is the rapid lofting, leading to enhanced vertical mixing, and projection downwind of the contaminant by the interaction of the winds with the urban landscape in the CFD model. This model-to-model discrepancy is partially ameliorated by supplying the puff model with more detailed information about the urban boundary layer that evolves on the CFD grid. While improving the correspondence of the models when using the "coarse-grain" statistic, the additional information does not lead to quite as substantial an overall agreement between the models when the "fine-grain" statistics are compared. The taller, denser and more variable building landscape of Chicago created increased sensitivity to release site and led to greater divergence in FAST3D-CT and SCIPUFF results relative to the flatter, sparser and more uniform urban morphology of Washington DC.

Pullen, Julie; Boris, Jay P.; Young, Theodore; Patnaik, Gopal; Iselin, John

122

Paducah Gaseous Diffusion Plant Northwest Plume interceptor system evaluation  

Microsoft Academic Search

The Paducah Gaseous Diffusion Plant (PGDP) recently installed an interceptor system consisting of four wells, evenly divided between two well fields, to contain the Northwest Plume. As stated in the Northwest Plume Record of Decision (ROD), groundwater will be pumped at a rate to reduce further contamination and initiate control of the northwest contaminant plume. The objective of this evaluation

A. D. Laase; J. L. Clausen

1998-01-01

123

Temporal variations in natural attenuation of chlorinated aliphatic hydrocarbons in eutrophic river sediments impacted by a contaminated groundwater plume.  

PubMed

Chlorinated aliphatic hydrocarbons (CAHs) often discharge into rivers as contaminated groundwater baseflow. Biotransformation, sorption and dilution of CAHs in the impacted river sediments have been reported to reduce discharge, but the effect of temporal variations in environmental conditions on the occurrence and extent of those processes in river sediments is largely unknown. We monitored the reduction of CAH discharge into the Zenne River during a 21-month period. Despite a relatively stable influx of CAHs from the groundwater, the total reduction in CAH discharge from 120 to 20 cm depth in the river sediments, on average 74 ± 21%, showed moderate to large temporal variations, depending on the riverbed location. High organic carbon and anaerobic conditions in the river sediments allowed microbial reductive dechlorination of both chlorinated ethenes and chlorinated ethanes. ?(13)C values of the CAHs showed that this biotransformation was remarkably stable over time, despite fluctuating pore water temperatures. Daughter products of the CAHs, however, were not detected in stoichiometric amounts and suggested the co-occurrence of a physical process reducing the concentrations of CAHs in the riverbed. This process was the main process causing temporal variations in natural attenuation of the CAHs and was most likely dilution by surface water-mixing. However, higher spatial resolution monitoring of flow transients in the riverbed is required to prove dilution contributions due to dynamic surface water-groundwater flow exchanges. ?(13)C values and a site-specific isotope enrichment factor for reductive dechlorination of the main groundwater pollutant vinyl chloride (VC) allowed assessment of changes over time in the extent of both biotransformation and dilution of VC for different scenarios in which those processes either occurred consecutively or simultaneously between 120 and 20 cm depth in the riverbed. The extent of reductive dechlorination of VC ranged from 27 to 89% and differed spatially but was remarkably stable over time, whereas the extent of VC reduction by dilution ranged from 6 to 94%, showed large temporal variations, and was often the main process contributing to the reduction of VC discharge into the river. PMID:22280951

Hamonts, Kelly; Kuhn, Thomas; Vos, Johan; Maesen, Miranda; Kalka, Harald; Smidt, Hauke; Springael, Dirk; Meckenstock, Rainer U; Dejonghe, Winnie

2012-04-15

124

A controlled field experiment on groundwater contamination by a multicomponent DNAPL: creation of the emplaced-source and overview of dissolved plume development.  

PubMed

A unique field experiment has been undertaken at the CFB Borden research site to investigate the development of dissolved chlorinated solvent plumes from a residual dense non-aqueous phase liquid (DNAPL) source. The "emplaced-source" tracer test methodology involved a controlled emplacement of a block-shaped source of sand containing chlorinated solvents below the water table. The gradual dissolution of this residual DNAPL solvent source under natural aquifer conditions caused dissolved solvent plumes of trichloromethane (TCM), trichloroethene (TCE) and perchloroethene (PCE) to continuously develop down gradient. Source dissolution and 3-D plume development were successfully monitored via 173 multilevel samplers over a 475-day tracer test period prior to site remediation research being initiated. Detailed groundwater level and hydraulic conductivity data were collected. Development of plumes with concentrations spanning 1-700,000 micrograms/1 is described and key processes controlling their migration identified. Plumes were observed to be narrow due to the weakness of transverse dispersion processes and long due to advection and significant longitudinal dispersion, very limited sorptive retardation and negligible, if any, attenuation due to biodegradation or abiotic reaction. TCM was shown to be essentially conservative, TCE very nearly conservative and PCE, consistent with its greater hydrophobicity, more retarded yet having a greater mobility than observed in previous Borden field tests. The absence of biodegradation was ascribed to the prevailing aerobic conditions and lack of any additional biodegradable carbon substrates. The transient groundwater flow regime caused significant transverse lateral plume movement, plume asymmetry and was likely responsible for most of the, albeit limited, transverse horizontal plume spreading. In agreement with the widespread incidence of extensive TCE and PCE plumes throughout the industrialized world, the experiment indicates such solvent plumes are likely to be highly mobile and persistent, at least in aquifers that are aerobic and have low sorption potential (low foc content). PMID:11351512

Rivett, M O; Feenstra, S; Cherry, J A

2001-05-01

125

A controlled field experiment on groundwater contamination by a multicomponent DNAPL: creation of the emplaced-source and overview of dissolved plume development  

NASA Astrophysics Data System (ADS)

A unique field experiment has been undertaken at the CFB Borden research site to investigate the development of dissolved chlorinated solvent plumes from a residual dense non-aqueous phase liquid (DNAPL) source. The "emplaced-source" tracer test methodology involved a controlled emplacement of a block-shaped source of sand containing chlorinated solvents below the water table. The gradual dissolution of this residual DNAPL solvent source under natural aquifer conditions caused dissolved solvent plumes of trichloromethane (TCM), trichloroethene (TCE) and perchloroethene (PCE) to continuously develop down gradient. Source dissolution and 3-D plume development were successfully monitored via 173 multilevel samplers over a 475-day tracer test period prior to site remediation research being initiated. Detailed groundwater level and hydraulic conductivity data were collected. Development of plumes with concentrations spanning 1-700,000 ?g/l is described and key processes controlling their migration identified. Plumes were observed to be narrow due to the weakness of transverse dispersion processes and long due to advection and significant longitudinal dispersion, very limited sorptive retardation and negligible, if any, attenuation due to biodegradation or abiotic reaction. TCM was shown to be essentially conservative, TCE very nearly conservative and PCE, consistent with its greater hydrophobicity, more retarded yet having a greater mobility than observed in previous Borden field tests. The absence of biodegradation was ascribed to the prevailing aerobic conditions and lack of any additional biodegradable carbon substrates. The transient groundwater flow regime caused significant transverse lateral plume movement, plume asymmetry and was likely responsible for most of the, albeit limited, transverse horizontal plume spreading. In agreement with the widespread incidence of extensive TCE and PCE plumes throughout the industrialized world, the experiment indicates such solvent plumes are likely to be highly mobile and persistent, at least in aquifers that are aerobic and have low sorption potential (low foc content).

Rivett, Michael O.; Feenstra, Stanley; Cherry, John A.

2001-05-01

126

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

127

Spatially resolved U(VI) partitioning and speciation: implications for plume scale behavior of contaminant U in the Hanford vadose zone.  

PubMed

A saline-alkaline brine containing high concentration of U(VI) was accidentally spilled at the Hanford Site in 1951, introducing 10 tons of U into sediments under storage tank BX-102. U concentrations in the deep vadose zone and groundwater plumes increase with time, yet how the U has been migrating is not fully understood. We simulated the spill event in laboratory soil columns, followed by aging, and obtained spatially resolved U partitioning and speciation along simulated plumes. We found after aging, at apparent steady state, that the pore aqueous phase U concentrations remained surprisingly high (up to 0.022 M), in close agreement with the recently reported high U concentrations (up to 0.027 M) in the vadose zone plume (1). The pH values of aged pore liquids varying from 10 to 7, consistent with the measured pH of the field borehole sediments varying from 9.5 to 7.4 (2), from near the plume source to the plume front. The direct measurements of aged pore liquids together with thermodynamic calculations using a Pitzer approach revealed that UO2(CO3)3(4-) is the dominant aqueous U species within the plume body (pH 8-10), whereas Ca2UO2(CO3)3 and CaUO2(CO3)32- are also significant in the plume frontvicinity (pH 7-8), consistent with that measured from field borehole pore-waters (3). U solid phase speciation varies at different locations along the plume flow path and even within single sediment grains, because of location dependent pore and micropore solution chemistry. Our results suggest that continuous gravity-driven migration of the highly stable U02(CO3)34 in the residual carbonate and sodium rich tank waste solution is likely responsible for the detected growing U concentrations in the vadose zone and groundwater. PMID:19452870

Wan, Jiamin; Kim, Yongman; Tokunaga, Tetsu K; Wang, Zheming; Dixit, Suvasis; Steefel, Carl I; Saiz, Eduardo; Kunz, Martin; Tamura, Nobumichi

2009-04-01

128

Spatially Resolved U(VI) Partitioning and Speciation: Implications for Plume Scale Behavior of Contaminant U in the Hanford Vadose Zone  

SciTech Connect

A saline-alkaline brine containing high concentration of U(VI) was accidentally spilled at the Hanford Site in 1951, introducing 10 tons of U into sediments under storage tank BX-102. U concentrations in the deep vadose zone and groundwater plumes increase with time, yet how the U has been migrating is not fully understood. We simulated the spill event in laboratory soil columns, followed by aging, and obtained spatially resolved U partitioning and speciation along simulated plumes. We found after aging, at apparent steady state, that the pore aqueous phase U concentrations remained surprisingly high (up to 0.022 M), in close agreement with the recently reported high U concentrations (up to 0.027 M) in the vadose zone plume (1). The pH values of aged pore liquids varying from 10 to 7, consistent with the measured pH of the field borehole sediments varying from 9.5 to 7.4 (2), from near the plume source to the plume front. The direct measurements of aged pore liquids together with thermodynamic calculations using a Pitzer approach revealed that UO2(CO3)34- is the dominant aqueousUspecies within the plume body (pH 8-10), whereas Ca2UO2(CO3)3 and CaUO2(CO3)32- are also significant in the plume front vicinity (pH 7-8), consistent with that measured from field borehole pore-waters (3). U solid phase speciation varies at different locations along the plume flow path and even within single sediment grains, because of location dependent pore and micropore solution chemistry. Our results suggest that continuous gravitydriven migration of the highly stable UO2(CO3)34- in the residual carbonate and sodium rich tank waste solution is likely responsible for the detected growing U concentrations in the vadose zone and groundwater.

Wan, Jiamin; Kim, Yongman; Tokunaga, Tetsu K.; Wang, Zheming; Dixit, Suvasis; Steefel, Carl I.; Saiz, Eduardo; Kunz, Martin; Tamura, Nobumichi

2009-04-01

129

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

130

Tvashtar's Plume  

NASA Technical Reports Server (NTRS)

This dramatic image of Io was taken by the Long Range Reconnaissance Imager (LORRI) on New Horizons at 11:04 Universal Time on February 28, 2007, just about 5 hours after the spacecraft's closest approach to Jupiter. The distance to Io was 2.5 million kilometers (1.5 million miles) and the image is centered at 85 degrees west longitude. At this distance, one LORRI pixel subtends 12 kilometers (7.4 miles) on Io.

This processed image provides the best view yet of the enormous 290-kilometer (180-mile) high plume from the volcano Tvashtar, in the 11 o'clock direction near Io's north pole. The plume was first seen by the Hubble Space Telescope two weeks ago and then by New Horizons on February 26; this image is clearer than the February 26 image because Io was closer to the spacecraft, the plume was more backlit by the Sun, and a longer exposure time (75 milliseconds versus 20 milliseconds) was used. Io's dayside was deliberately overexposed in this picture to image the faint plumes, and the long exposure also provided an excellent view of Io's night side, illuminated by Jupiter. The remarkable filamentary structure in the Tvashtar plume is similar to details glimpsed faintly in 1979 Voyager images of a similar plume produced by Io's volcano Pele. However, no previous image by any spacecraft has shown these mysterious structures so clearly.

The image also shows the much smaller symmetrical fountain of the plume, about 60 kilometers (or 40 miles) high, from the Prometheus volcano in the 9 o'clock direction. The top of a third volcanic plume, from the volcano Masubi, erupts high enough to catch the setting Sun on the night side near the bottom of the image, appearing as an irregular bright patch against Io's Jupiter-lit surface. Several Everest-sized mountains are highlighted by the setting Sun along the terminator, the line between day and night.

This is the last of a handful of LORRI images that New Horizons is sending 'home' during its busy close encounter with Jupiter -- hundreds of images and other data are being taken and stored onboard. The rest of the images will be returned to Earth over the coming weeks and months as the spacecraft speeds along to Pluto.

2007-01-01

131

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

132

Spatially resolved U(VI) partitioning and speciation: Implications for plume scale behavior of contaminant U in the Hanford vadose zone  

SciTech Connect

A saline-alkaline brine containing high concentrations of U(VI) was accidentally spilled at the Hanford Site in 1951, introducing 10 tons of U into sediments under storage tank BX-102. U concentrations in the deep vadose zone and groundwater plumes increase with time, yet how the U has been migrating is not fully understood. We simulated the spill event in laboratory soil columns, followed by aging, and obtained spatially resolved U partitioning and speciation along simulated plumes. We found after aging, at apparent steady state, that the pore aqueous phase U concentrations remained surprisingly high (up to 0.022 M), in close agreement with the recently reported high U concentrations (up to 0.027 M) in the vadose zone plume (1). The pH values of aged pore liquids varying from 10 to 7, consistent with the measured pH of the field borehole sediments varying from 9.5 to 7.4 (2), from near the plume source to the plume front. The direct measurements of aged pore liquids together with thermodynamic calculations using a Pitzer approach revealed that UO{sub 2}(CO{sub 3}){sub 3} {sup 4-} is the dominant aqueous U species within the plume body (pH 8-10), while Ca{sub 2}UO{sub 2}(CO{sub 3}){sub 3} and CaUO{sub 2}(CO{sub 3}){sub 3}{sup 2-} are also significant in the plume front vicinity (pH 7-8), consistent with that measured from field borehole porewaters (3). U solid phase speciation varies at different locations along the plume flow path and even within single sediment grains, because of location dependent pore and micropore solution chemistry. Our results suggest that high geochemical stability of UO{sub 2}(CO{sub 3}){sub 3}{sup 4-} in the original carbonate and sodium rich waste solution permits its continues migration and the field observed increases of U concentrations in the vadose zone and groundwater.

Wan, Jiamin; Kim, Yongman; Tokunaga, Tetsu K.; Wang, Zheming; Dixit, Suvasis; Steefel, Carl; Saiz, Eduardo; Kunz, Martin; Tamura, Nobumichi

2009-02-01

133

Identification of Unknown Groundwater Pollution Sources Using Feedback Based Linked simulation-Optimization model at a Contaminated site  

Microsoft Academic Search

Abstract A feedback,based methodology,has been developed,for identifying the unknown,pollution sources in groundwater contaminated,aquifers. The methodology,consists of models within an iterative feedback system, with the capacity of feeding back real-time measurements of pollutant concentrations,for the sequential optimal,designs,and,characterization of the contaminated,aquifer study area. The resulting linked-simulation optimization model considers the delineation of the contaminant plume, optimally characterizing the site in terms of

Sreenivasulu Chadalavada; Bithin Datta; Ravi Naidu

134

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.

Babcock, Matthew; Mayer, Alex; Curriculum, Michigan E.

135

Delineation of ecosystem regions  

Microsoft Academic Search

As a means of developing reliable estimates of ecosystem productivity, ecosystem classification needs to be placed within a geographical framework of regions or zones. This paper explains the basis for the regions delineated on the 1976 mapEcoregions of the United States. Four ecological levels are discussed—domain, division, province, and section—based on climatic and vegetational criteria. Statistical tests are needed to

Robert G. Bailey; Fort Collins

1983-01-01

136

Candida albicans strain delineation.  

PubMed Central

Candida albicans is a major opportunistic pathogen causing a wide spectrum of disease in human beings. Methods for strain delineation of this species to assess or predict virulence or to conduct epidemiologic or pathogenetic investigations have been developed. Although factors associated with virulence have been identified, there is no rapid system to quantitate them in a clinical laboratory. Therefore, many typing methods are based on variable phenotypic characteristics within this species including morphotyping, serotyping, antibiogram, resistogram typing, biotyping, biotyping based on commercial carbon assimilation patterns, enzyme profiles, sensitivity to yeast killer toxins, and typing based on protein variability. Phenotypically defined strains generally do not correlate with the pathogenic potential of a strain with the exception of morphotyping. However, these methods can be useful in epidemiologic investigations; for example, they have revealed that most individuals harbor one strain and that infections are frequently due to an endogenous strain. Problems with these methods usually relate to their discriminatory power. When this is maximized, reproducibility (especially between laboratories) suffers. Recently, methods based on differences in DNA structure (genotyping) for strain delineation have been developed, including electrophoretic karyotyping and restriction enzyme fragment length polymorphisms. The development of a computer-assisted data bank and analysis for these genotypic strain delineators will open investigations into the pathogenesis of this infection and permit epidemiologic studies previously not possible with this important human pathogen.

Merz, W G

1990-01-01

137

A controlled field experiment on groundwater contamination by a multicomponent DNAPL: creation of the emplaced-source and overview of dissolved plume development  

Microsoft Academic Search

A unique field experiment has been undertaken at the CFB Borden research site to investigate the development of dissolved chlorinated solvent plumes from a residual dense non-aqueous phase liquid (DNAPL) source. The “emplaced-source” tracer test methodology involved a controlled emplacement of a block-shaped source of sand containing chlorinated solvents below the water table. The gradual dissolution of this residual DNAPL

Michael O Rivett; Stanley Feenstra; John A Cherry

2001-01-01

138

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

Microsoft Academic Search

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

M. L. Brusseau; Kenneth C. Carroll; Tim J. Allen; Joseph R. Baker; W. DiGuiseppi; J. Hatton; C. Morrison; A. Russo; J. Berkompas

2011-01-01

139

River Plumes in Sunglint, Sarawak, Borneo  

NASA Technical Reports Server (NTRS)

The sunglint pattern along the coast of Sarawak (3.0N, 111.5E) delineates the boundry of fresh water river plumes as they flow into the South China Sea. The fresh water lens (boundry between fresh and sea water) overides the saline and more dense sea water and oils, both natural and man made, collect along the convergence zones and dampen wave action. As a result, the smoother sea surface appears bright in the sunglint pattern.

1991-01-01

140

Geochemical and microbiological methods for evaluating anaerobic processes in an aquifer contaminated by landfill leachate  

USGS Publications Warehouse

A combined geochemical and microbiological approach was needed to delineate the biogeochemical processes occurring in an aquifer contaminated by landfill leachate in Norman, OK, where the important microbially mediated reactions in an anoxic plume were iron reduction, sulfate reduction, and methanogenesis. The highest rates of sulfate reduction (13.2 ??M/day) were detected near the water table where sulfate levels were maximal (up to 4.6 mM). The enrichment of 34S in the sulfate pools (??34S of SO42- was 67-69%0), and dissolved hydrogen measurements provided additional support for the importance of sulfate reduction near the water table. Methane was detected in the center of the plume where sulfate was depleted. Microbial incubations demonstrated concomitant sulfate reduction and methanogenesis in the anoxic portion of the plume. Although high concentrations of soluble reduced iron were detected throughout the aquifer and H2 levels were indicative of iron reduction under steady-state conditions, microbiological experiments showed that iron reduction was active only at the edges of the sulfate-depleted portion of the plume. This study demonstrates the benefits of using a combined geochemical and microbiological approach to elucidate the spatial distribution of biogeochemical processes in contaminated aquifers.A combined geochemical and microbiological approach was needed to delineate the biogeochemical processes occurring in an aquifer contaminated by landfill leachate in Norman, OK, where the important microbially mediated reactions in an anoxic plume were iron reduction, sulfate reduction, and methanogenesis. The highest rates of sulfate reduction (13.2 ??M/day) were detected near the water table where sulfate levels were maximal (up to 4.6 mM). The enrichment of 34S in the sulfate pools (??34S of SO42- was 67-69 per mil), and dissolved hydrogen measurements provided additional support for the importance of sulfate reduction near the water table. Methane was detected in the center of the plume where sulfate was depleted. Microbial incubations demonstrated concomitant sulfate reduction and methanogenesis in the anoxic portion of the plume. Although high concentrations of soluble reduced iron were detected throughout the aquifer and H2 levels were indicative of iron reduction under steady-state conditions, microbiological experiments showed that iron reduction was active only at the edges of the sulfate-depleted portion of the plume. This study demonstrates the benefits of using a combined geochemical and microbiological approach to elucidate the spatial distribution of biogeochemical processes in contaminated aquifers.

Cozzarelli, I. M.; Suflita, J. M.; Ulrich, G. A.; Harris, S. H.; Scholl, M. A.; Schlottmann, J. L.; Christenson, S.

2000-01-01

141

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

142

Subduction disfigured mantle plumes: Plumes that are not plumes?  

NASA Astrophysics Data System (ADS)

"Hotspot" volcanism is generally attributed to upwelling of anomalously warm mantle plumes, the intra-plate Hawaiian island chain and its simple age progression serving as an archetypal example. However, interactions of such plumes with plate margins, and in particular with subduction zones, is likely to have been a common occurrence and leads to more complicated geological records. Here we present results from a series of complementary, three-dimensional numerical and laboratory experiments that examine the dynamic interaction between negatively buoyant subducting slabs and positively buoyant mantle plumes. Slab-driven flow is shown to significantly influence the evolution and morphology of nearby plumes, which leads to a range of deformation regimes of the plume head and conduit. The success or failure of an ascending plume head to reach the lithosphere depends on the combination of plume buoyancy and position within the subduction system, where the mantle flow owing to downdip and rollback components of slab motion entrain plume material both vertically and laterally. Plumes rising within the sub-slab region tend to be suppressed by the surrounding flow field, while wedge-side plumes experience a slight enhancement before ultimately being entrained by subduction. Hotspot motion is more complex than that expected at intraplate settings and is primarily controlled by position alone. Regimes include severely deflected conduits as well as retrograde (corkscrew) motion from rollback-driven flow, often with weak and variable age-progression. The interaction styles and surface manifestations of plumes can be predicted from these models, and the results have important implications for potential hotspot evolution near convergent margins.

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

2012-12-01

143

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

144

Model based evaluation of a contaminant plume development under aerobic and anaerobic conditions in 2D bench-scale tank experiments.  

PubMed

The influence of transverse mixing on competitive aerobic and anaerobic biodegradation of a hydrocarbon plume was investigated using a two-dimensional, bench-scale flow-through laboratory tank experiment. In the first part of the experiment aerobic degradation of increasing toluene concentrations was carried out by the aerobic strain Pseudomonas putida F1. Successively, ethylbenzene (injected as a mixture of unlabeled and fully deuterium-labeled isotopologues) substituted toluene; nitrate was added as additional electron acceptor and the anaerobic denitrifying strain Aromatoleum aromaticum EbN1 was inoculated to study competitive degradation under aerobic /anaerobic conditions. The spatial distribution of anaerobic degradation was resolved by measurements of compound-specific stable isotope fractionation induced by the anaerobic strain as well as compound concentrations. A fully transient numerical reactive transport model was employed and calibrated using measurements of electron donors, acceptors and isotope fractionation. The aerobic phases of the experiment were successfully reproduced using a double Monod kinetic growth model and assuming an initial homogeneous distribution of P. putida F1. Investigation of the competitive degradation phase shows that the observed isotopic pattern cannot be explained by transverse mixing driven biodegradation only, but also depends on the inoculation process of the anaerobic strain. Transient concentrations of electron acceptors and donors are well reproduced by the model, showing its ability to simulate transient competitive biodegradation. PMID:24122285

Ballarini, E; Beyer, C; Bauer, R D; Griebler, C; Bauer, S

2014-06-01

145

Challenges in monitoring the natural attenuation of spatially variable plumes.  

PubMed

Monitored natural attenuation may be applied as a risk-based remediation strategy if it can be established that contaminants are or will be reduced to some acceptable level at or before a compliance point. Contaminant attenuation is often attributed to intrinsic biodegradation, which in some circumstances may occur only at the plume fringes where electron acceptors from the surrounding uncontaminated zones mix by dispersion and diffusion with the plume. However, due to the common spatial and temporal variability exhibited by many plumes, the centreline monitoring approaches advocated in many natural attenuation protocols may be unable to detect natural attenuation occurring primarily by fringe processes. Snapshot data from a multilevel sampling well transect across an MTBE plume at Vandenberg Air Force Base, CA, USA, illustrate the difficulty of centreline monitoring and the challenge of providing sufficient detail to detect attenuation processes that may be occurring primarily at plume fringes. In a study of a phenols plume in Wolverhampton, UK, high-resolution multilevel wells demonstrated that the key biodegradation processes were restricted spatially to the upper fringe of the plume and were rate-limited by transverse dispersion and diffusion of electron acceptors into the plume. Thus the overall extent of biodegradation was considerably less than suggested by a plume-scale analysis of total electron acceptor and contaminant budgets. These examples indicate that more robust and cost-effective MNA assessments can be obtained using monitoring strategies that focus on the location of key biodegradation processes. PMID:15562994

Wilson, Ryan D; Thornton, Steven F; Mackay, Douglas M

2004-12-01

146

Evaluating Chlorinated Hydrocarbon Plume Behavior Using Historical Case Population Analyses  

Microsoft Academic Search

A nationwide survey of chlorinated volatile organic compound (CVOC) plumes was conducted across a spectrum of sites from diverse hydrogeologic environments and contaminant release scenarios. The goal was to evaluate significant trends in the data that relate plume behavior to site variables (e.g., source strength, mean groundwater velocity, reductive dehalogenation regime) through correlation and population analyses. Data from 65 sites

Walt W. McNab; David W. Rice; Cary Tuckfield

2000-01-01

147

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

148

Isotopic mapping of groundwater perchlorate plumes.  

PubMed

Analyses of stable isotope ratios of chlorine and oxygen in perchlorate can, in some cases, be used for mapping and source identification of groundwater perchlorate plumes. This is demonstrated here for large, intersecting perchlorate plumes in groundwater from a region having extensive groundwater perchlorate contamination and a large population dependent on groundwater resources. The region contains both synthetic perchlorate derived from rocket fuel manufacturing and testing activities and agricultural perchlorate derived predominantly from imported Chilean (Atacama) nitrate fertilizer, along with a likely component of indigenous natural background perchlorate from local wet and dry atmospheric deposition. Most samples within each plume reflect either a predominantly synthetic or a predominantly agricultural perchlorate source and there is apparently a minor contribution from the indigenous natural background perchlorate. The existence of isotopically distinct perchlorate plumes in this area is consistent with other lines of evidence, including groundwater levels and flow paths as well as the historical land use and areal distribution of potential perchlorate sources. PMID:21352209

Sturchio, Neil C; Hoaglund, John R; Marroquin, Roy J; Beloso, Abelardo D; Heraty, Linnea J; Bortz, Sarah E; Patterson, Thomas L

2012-01-01

149

Comparative Study of Numerical Delineation for Wellhead Protection Area under Steady-State and Transient State  

Microsoft Academic Search

Groundwater protection is of great importance in terms of public health and environmental safety. Wellhead Protection Area (WHPA) Delineation is a basic and effective measurement for protecting groundwater from contaminated. Different methods of WHPA delineation can be selected depending on the feasible data and complexity of the hydrogeologic conditions, during which numerical simulation is one of the most popular methods.

Haizhen Xu; Guomin Li; Yanhui Dong; Ming Li; Shouquan Zhang

2011-01-01

150

Improving the delineation of hydrocarbon-impacted soils and water through induced polarization (IP) tomographies: a field study at an industrial waste land.  

PubMed

Without a good estimation of samples representativeness, the delineation of the contaminated plume extent and the evaluation of volumes of hydrocarbon-impacted soils may remain difficult. To contribute to this question, a time domain induced polarization (IP) field experiment was conducted on an industrial waste land. Boreholes were drilled to specify the local geological context. Cross-hole seismic tomographies were performed to extend borehole logs and to draw an interpreted geological cross-section. Soil samples taken during drillings were analysed in laboratory. A preliminary survey was conducted to locate the IP profile. The polarization signatures linked to the presence of clayey sediments were filtered out from the data set. Chargeability and resistivity depth soundings were computed and compared to mean concentrations of total organic products to overcome the data support issue between the geophysical models and the spot samples of soils. A logarithmic relation between chargeabilities and smoothed hydrocarbon concentrations in soils was found. Taking into account contaminant's concentration thresholds defined in local codes and regulations allows defining chargeability classes to delineate hotspots on this site. This showed that IP tomography can be an accurate screening methodology. A statistical methodology is proposed to assess the efficiency of the investigation strategy. PMID:22659399

Deceuster, John; Kaufmann, Olivier

2012-08-01

151

Improving the delineation of hydrocarbon-impacted soils and water through induced polarization (IP) tomographies: A field study at an industrial waste land  

NASA Astrophysics Data System (ADS)

Without a good estimation of samples representativeness, the delineation of the contaminated plume extent and the evaluation of volumes of hydrocarbon-impacted soils may remain difficult. To contribute to this question, a time domain induced polarization (IP) field experiment was conducted on an industrial waste land. Boreholes were drilled to specify the local geological context. Cross-hole seismic tomographies were performed to extend borehole logs and to draw an interpreted geological cross-section. Soil samples taken during drillings were analysed in laboratory. A preliminary survey was conducted to locate the IP profile. The polarization signatures linked to the presence of clayey sediments were filtered out from the data set. Chargeability and resistivity depth soundings were computed and compared to mean concentrations of total organic products to overcome the data support issue between the geophysical models and the spot samples of soils. A logarithmic relation between chargeabilities and smoothed hydrocarbon concentrations in soils was found. Taking into account contaminant's concentration thresholds defined in local codes and regulations allows defining chargeability classes to delineate hotspots on this site. This showed that IP tomography can be an accurate screening methodology. A statistical methodology is proposed to assess the efficiency of the investigation strategy.

Deceuster, John; Kaufmann, Olivier

2012-08-01

152

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

2014-04-01

153

Subsurface contaminants focus area  

SciTech Connect

The US Department of Enregy (DOE) Subsurface Contaminants Focus Area is developing technologies to address environmental problems associated with hazardous and radioactive contaminants in soil and groundwater that exist throughout the DOE complex, including radionuclides, heavy metals; and dense non-aqueous phase liquids (DNAPLs). More than 5,700 known DOE groundwater plumes have contaminated over 600 billion gallons of water and 200 million cubic meters of soil. Migration of these plumes threatens local and regional water sources, and in some cases has already adversely impacted off-site rsources. In addition, the Subsurface Contaminants Focus Area is responsible for supplying technologies for the remediation of numerous landfills at DOE facilities. These landfills are estimated to contain over 3 million cubic meters of radioactive and hazardous buried Technology developed within this specialty area will provide efective methods to contain contaminant plumes and new or alternative technologies for development of in situ technologies to minimize waste disposal costs and potential worker exposure by treating plumes in place. While addressing contaminant plumes emanating from DOE landfills, the Subsurface Contaminants Focus Area is also working to develop new or alternative technologies for the in situ stabilization, and nonintrusive characterization of these disposal sites.

NONE

1996-08-01

154

The elusive mantle plume  

NASA Astrophysics Data System (ADS)

Mantle plumes are hypothetical hot, narrow mantle upwellings that are often invoked to explain hotspot volcanism with unusual geophysical and geochemical characteristics. The mantle plume is a well-established geological structure in computer modeling and laboratory experiments but an undisputed seismic detection of one has yet to be made. Vertically continuous low shear velocity anomalies in the upper mantle, expected for plumes, are present beneath the Afar, Bowie, Easter, Hawaii, Iceland, Louisville, McDonald, and Samoa hotspots but not beneath the other 29 hotspots in Sleep's 1990 catalog. Whether and how plumes form remain fundamental multi-disciplinary research questions. Should they exist, detection of whole-mantle plumes will depend on deployments of dense (50-100 km station spacing), wide-aperture (>1000 km) seismic networks to maximize model resolution in the transition zone and uppermost lower mantle since plume impingement upon the 660-km phase transition leaves a unique seismic imprint.

Ritsema, Jeroen; Allen, Richard M.

2003-02-01

155

Delineating alluvial aquifer heterogeneity using resistivity and GPR data.  

PubMed

Conceptual geological models based on geophysical data can elucidate aquifer architecture and heterogeneity at meter and smaller scales, which can lead to better predictions of preferential flow pathways. The macrodispersion experiment (MADE) site, with >2000 measurements of hydraulic conductivity obtained and three tracer tests conducted, serves as an ideal natural laboratory for examining relationships between subsurface flow characteristics and geophysical attributes in fluvial aquifers. The spatial variation of hydraulic conductivity measurements indicates a large degree of site heterogeneity. To evaluate the usefulness of geophysical methods for better delineating fluvial aquifer heterogeneities and distribution of preferential flow paths, a surface grid of two-dimensional ground penetrating radar (GPR) and direct current (DC) resistivity data were collected. A geological model was developed from these data that delineate four stratigraphic units with distinct electrical and radar properties including (from top to bottom) (1) a meandering fluvial system (MFS); (2) a braided fluvial system (BFS); (3) fine-grained sands; and (4) a clay-rich interval. A paleochannel, inferred by other authors to affect flow, was mapped in the MFS with both DC resistivity and GPR data. The channel is 2 to 4 m deep and, based on resistivity values, is predominantly filled with clay and silt. Comparing previously collected hydraulic conductivity measurements and tracer-plume migration patterns to the geological model indicates that flow primarily occurs in the BFS and that the channel mapped in the MFS has no influence on plume migration patterns. PMID:16324010

Bowling, Jerry C; Rodriguez, Antonio B; Harry, Dennis L; Zheng, Chunmiao

2005-01-01

156

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

157

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...

158

Stealth plumes on Io  

NASA Astrophysics Data System (ADS)

We suggest that Io's eruptive activity may include a class of previously undetected SO2 geysers. The thermodynamic models for the eruptive plumes discovered by Voyager involve low to moderate entropy SO2 eruptions. The resulting plumes are a mixture of solid and gas which emerge from the vent and follow essentially ballistic trajectories. We show that intrusion of silicate magma into buried SO2 deposits can create the required conditions for high entropy eruptions which proceed entirely in the vapor phase. These purely gaseous plumes would have been invisible to Voyager's instruments. Hence, we call them “stealth” plumes. Such eruptions could explain the “patchy” SO2 atmosphere inferred from recent UV and microwave spectral observations. The magma intrusion rate required to support the required gas production for these plumes is a negligible fraction of estimated global magma intrusion rates.

Johnson, Torrence V.; Matson, Dennis L.; Blaney, Diana L.; Veeder, Glenn J.; Davies, Ashley

159

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

160

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

161

The plume impingement test program at AEDC utilizing the S-2 ullage motors (November 1973), section 1  

NASA Technical Reports Server (NTRS)

Proposed experiments for analyzing rocket plumes are reported. Two groups of experiments were studied: (1) those that would help define some of the parameters that characterize the plume and (2) those that would enable evaluation of some of the contamination effects of the plume environment on various items of interest. The items investigated, the purpose of the investigation, are given in tabular form.

1976-01-01

162

Modeling Remediation of Chlorinated Solvent Plumes  

Microsoft Academic Search

\\u000a Analytical and numerical modeling has emerged as a valuable tool for planning and designing groundwater remediation systems.\\u000a Models have been used in a variety of settings including (1) research into the fundamental processes controlling chlorinated\\u000a solvent fate and transport, (2) methods for integrating information on site hydrology, geology, contaminant distribution,\\u000a transport and fate, and (3) applied aspects of plume management

Hanadi S. Rifai; Robert C. Borden; Charles J. Newell; Philip B. Bedient

163

Methane Plumes on Mars  

NASA Video Gallery

Spectrometer instruments attached to several telescopes detect plumes of methane emitted from Mars during its summer and spring seasons. High levels of methane are indicated by warmer colors. The m...

164

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

165

Electrification of volcanic plumes  

NASA Astrophysics Data System (ADS)

Volcanic lightning, perhaps the most spectacular consequence of the electrification of volcanic plumes, has been implicated in the origin of life on Earth, and may also exist in other planetary atmospheres. Recent years have seen volcanic lightning detection used as part of a portfolio of developing techniques to monitor volcanic eruptions. Remote sensing measurement techniques have been used to monitor volcanic lightning, but surface observations of the atmospheric electric Potential Gradient (PG) and the charge carried on volcanic ash also show that many volcanic plumes, whilst not sufficiently electrified to produce lightning, have detectable electrification exceeding that of their surrounding environment. Electrification has only been observed associated with ash-rich explosive plumes, but there is little evidence that the composition of the ash is critical to its occurrence. Different conceptual theories for charge generation and separation in volcanic plumes have been developed to explain the disparate observations obtained, but the ash fragmentation mechanism appears to be a key parameter. It is unclear which mechanisms or combinations of electrification mechanisms dominate in different circumstances. Electrostatic forces play an important role in modulating the dry fall-out of ash from a volcanic plume. Beyond the local electrification of plumes, the higher stratospheric particle concentrations following a large explosive eruption may affect the global atmospheric electrical circuit. It is possible that this might present another, if minor, way by which large volcanic eruptions affect global climate. The direct hazard of volcanic lightning to communities is generally low compared to other aspects of volcanic activity.

Mather, T. A.; Harrison, R. G.

2006-07-01

166

Titan Plumes Revisited  

NASA Astrophysics Data System (ADS)

At the time of the Voyager 1 close encounter with Titan, enhancements of density and sharp decreases of electron temperature were observed by the PLS instrument. A few smaller plumes were identified inside and outside Titan orbit and their displacements correlated with variations in solar wind dynamic pressure observed by Voyager PLS one and two corotation periods earlier. At the time, two conflicting interpretations of this phenomenon were proposed. In one interpretation (Eviatar et al., JGR, 87, 8091, 1982, the enhancements were regarded as plumes drawn out of the ionosphere of Titan by the corotation electric field. The secondary enhancements were taken to be old plumes that had been wrapped around Saturn, had begun to decay and to merge into the magnetosphere environment. An alternative interpretation, proposed by Goertz (GRL, 1983, 10, 455), viewed them as blobs of plasmas detached by flute or Kelvin-Helmholtz instability from the central body of Saturn plasma in the inner magnetosphere. The Voyager PLS instrument was unable to make a firm composition determination which would have resolved the question. In this study, we use Cassini/CAPS data to identify plumes and blobs of plasma and classify them by source by means of composition and temperature. We find that all three types of plasma bodies, primary plumes, secondary wrapped around plumes and sloughed off blobs exist in the Titan-dominated region of the magnetosphere.

Eviatar, A.; Goldstein, R.; Young, D. T.; Arridge, C. S.; Coates, A. J.; Sittler, E. C.; Thomsen, M. F.; Wilson, R. J.

2008-12-01

167

Electrification of volcanic plumes  

NASA Astrophysics Data System (ADS)

We present a review of our current understanding of the electrification of volcanic plumes on Earth and discuss the possible implications both in terms of the volcanic monitoring, early Earth evolution and planetary exploration. Volcanic lightning is perhaps the most spectacular consequence of the electrification of volcanic plumes. Recent years have seen volcanic lightning detection used as part of a portfolio of developing techniques to monitor volcanic eruptions. Remote sensing measurement techniques have been used to monitor volcanic lightning, but surface observations of the atmospheric electric Potential Gradient (PG) and the charge carried on volcanic ash also show that many volcanic plumes, whilst not sufficiently electrified to produce lightning, have detectable electrification exceeding that of their surrounding environment. Electrification has only been observed associated with ash-rich explosive plumes, but there is little evidence that the composition of the ash is critical to its occurrence. Different conceptual theories for charge generation and separation in volcanic plumes have been developed to explain the disparate observations obtained, but the ash fragmentation mechanism appears to be a key parameter. It is unclear which mechanisms or combinations of electrification mechanisms dominate in different circumstances. Electrostatic forces play an important role in modulating the dry fall-out of ash from a volcanic plume. Beyond the local electrification of plumes, the higher stratospheric particle concentrations following a large explosive eruption may affect the global atmospheric electrical circuit. It is possible that this might present another, if minor, way by which large volcanic eruptions affect global climate. Volcanic lightning has been implicated in a number of ways in the origin of life on Earth, and may also exist in other planetary atmospheres where measurements of its occurrence might give clues about the nature of volcanism on other planets. The direct hazard of volcanic lightning to communities on Earth is generally low compared to other aspects of volcanic activity.

Mather, T. A.; Harrison, R. G.

168

Martian Atmospheric Plumes: Behavior, Detectability and Plume Tracing  

NASA Astrophysics Data System (ADS)

We will present our recent work simulating neutrally buoyant plumes in the martian atmosphere. This work is primarily directed at understanding the behavior of discrete plumes of biogenic tracer gases, and thus increasing our understanding of their detectability (both from orbit and from in situ measurements), and finally how to use the plumes to identify their precise source locations. We have modeled the detailed behavior of martian atmospheric plumes using MarsWRF for the atmospheric dynamics and SCIPUFF (a terrestrial state of the art plume modeling code that we have modified to represent martian conditions) for the plume dynamics. This combination of tools allows us to accurately simulate plumes not only from a regional scale from which an orbital observing platform would witness the plume, but also from an in situ perspective, with the instantaneous concentration variations that a turbulent flow would present to a point sampler in situ instrument. Our initial work has focused on the detectability of discrete plumes from an orbital perspective and we will present those results for a variety of notional orbital trace gas detection instruments. We have also begun simulating the behavior of the plumes from the perspective of a sampler on a rover within the martian atmospheric boundary layer. The detectability of plumes within the boundary layer has a very strong dependence on the atmospheric stability, with plume concentrations increasing by a factor of 10-1000 during nighttime when compared to daytime. In the equatorial regions of the planet where we have simulated plumes, the diurnal tidal “clocking” of the winds is strongly evident in the plume trail, which similarly “clocks” around its source. This behavior, combined with the strong diurnal concentration variations suggests that a rover hunting a plume source would be well suited to approach it from a particular azimuth (downwind at night) to maximize detectability of the plume and the ability to trace the plume to its precise source.

Banfield, Don; Mischna, M.; Sykes, R.; Dissly, R.

2013-10-01

169

Utilisation des plumes dans la recherche des sources de contamination des oiseaux par les elements traces: Cd, Cu, Hg, Pb, Se, ET Zn chez les flamants De Camargue, France  

Microsoft Academic Search

Résumé Pour douze flamants trouvée morts en Camargue pendant un hiver rigoureux, les concentrations en éléments traces ont été déterminées dans le foie, les reins, les muscles pectoraux, les poumons et les trois premières rémiges primaires. De plus, pour trois individus les analyses ont porté sur les différents types de plumes. A la suite de cette étude, il paraît indispensable

Richard P. Cosson; Claude Amiard-Triquet; Jean-Claude Amiard

1988-01-01

170

Biogeochemical evolution of a landfill leachate plume, Norman, Oklahoma.  

PubMed

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. PMID:21314684

Cozzarelli, I M; Böhlke, J K; Masoner, J; Breit, G N; Lorah, M M; Tuttle, M L W; Jaeschke, J B

2011-01-01

171

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.

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

2011-01-01

172

Mixing in plume conduits  

NASA Astrophysics Data System (ADS)

The radial model of plume conduits (Hauri et al., 1996; Bryce et al., 2005) predicts that vertical concentric sheaths of variable compositions control the geochemical properties of volcanoes overriding hotspots. A variant of this model was proposed by Eisele et al. (2003) and Abouchami et al. (2005), who described a plume conduit as composed of long filaments representing heterogeneities present in the lower mantle and sheared during upwelling by radial velocity gradients. These two groups of models share their emphasis on the dominantly lateral character of heterogeneities. Blichert-Toft et al. (2003) pointed out that the vertical component of heterogeneities should not be neglected and considered an alternative extreme model of plug flow. Here we re-examine the basic physics of flow and show that vertical heterogeneity `trains' should be dominant. We first consider an axi-symmetric plume with homogeneous rheological properties assuming that temperature is decreasing and therefore viscosity increasing radially outwards. The physics of the flow in such a plume was described by Olson et al. (1993) and its geometry is known as poloidal. In the core of the conduit, the flow rate is maximum (high temperature, high buoyancy, low viscosity) and the rate of shear is minimum (the velocity gradient vanishes in the center), and therefore the vertical stretching of heterogeneities is minimal. Because of the temperature-dependent viscosity, the flow rate drops rapidly at some distance from the core: this is where the velocity gradient is maximum. Along this apparent discontinuity, the rate of shear is maximum, but the flow rate is much smaller than in the core. The trade-off between shear and flow rate requires that plume flow is dominated by the core of the conduit, which transports deep-seated heterogeneities with little shear, whereas the sheared, geochemically heterogeneous outer layers lag behind. We then considered the effect of objects in the plume conduit with different rheologies such as bodies of pyroxenite. Hard nuggets add a strong toroidal component to the velocity field because the flow lines wrap around the petrological obstacles. Such a component is known to be critical to mixing behavior. The nuggets also enhance flow instabilities because viscous drag exerts a lift effect on heterogeneities, which then wobble in the flow field. However paradoxical, the petrological heterogeneity of the plume source promotes vigorous mixing within the plume conduit, which is consistent with the long-term isotopic homogeneity observed in Hawaiian volcanoes at the shield stage. We thus reiterate Blichert-Toft et al.'s (2003) statement that long-wavelength vertical heterogeneity trains dominate the geochemical variability of hotspot volcanoes.

Bichert-Toft, J.; Albarede, F.

2006-12-01

173

Io Pele plume  

NASA Technical Reports Server (NTRS)

Voyager 1 took this narrow-angle camera image on 5 March 1979 from a distance of 450,000 kilometers. At this geometry, the camera looks straight down through a volcanic plume at one of Io's most active volcanos, Pele. The large heart-shaped feature is the region where Pele's plume falls to the surface. At the center of the 'heart' is the small dark fissure that is the source of the eruption. The Voyager Project is managed by the Jet Propulsion Laboratory for NASA's Office of Space Science.

2000-01-01

174

Assessment of groundwater contamination by landfill leachate: a case in México.  

PubMed

In México, uncontrolled landfills or open-dumps are regularly used as "sanitary landfills". Interactions between landfills/open-dumps and shallow unconfined aquifers have been widely documented. Therefore, evidence showing the occurrence of aquifer contamination may encourage Mexican decision makers to enforce environmental regulations. Traditional methods such as chemical analysis of groundwater, hydrological descriptions, and geophysical studies including vertical electrical sounding (VES) and ground penetrating radar (GPR) were used for the identification and delineation of a contaminant plume in a shallow aquifer. The Guadalupe Victoria landfill located in Mexicali is used as a model study site. This landfill has a shallow aquifer of approximately 1m deep and constituted by silty sandy soil that may favor the transport of landfill leachate. Geophysical studies show a landfill leachate contaminant plume that extends for 20 and 40 m from the SE and NW edges of the landfill, respectively. However, the zone of the leachate's influence stretches for approximately 80 m on both sides of the landfill. Geochemical data corroborates the effects of landfill leachate on groundwater. PMID:18595685

Reyes-López, Jaime A; Ramírez-Hernández, Jorge; Lázaro-Mancilla, Octavio; Carreón-Diazconti, Concepción; Garrido, Miguel Martín-Loeches

2008-01-01

175

Mixing-controlled biodegradation in a toluene plume — Results from two-dimensional laboratory experiments  

Microsoft Academic Search

Various abiotic and biotic processes such as sorption, dilution, and degradation are known to affect the fate of organic contaminants, such as petroleum hydrocarbons in saturated porous media. Reactive transport modeling of such plumes indicates that the biodegradation of organic pollutants is, in many cases, controlled by mixing and therefore occurs locally at the plume's fringes, where electron donors and

Robert D. Bauer; Piotr Maloszewski; Yanchun Zhang; Rainer U. Meckenstock; Christian Griebler

2008-01-01

176

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

177

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

178

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

179

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

180

Double Diffusive Plumes  

NASA Astrophysics Data System (ADS)

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 ground level in realistic atmospheric conditions. As a first step towards this goal we have performed laboratory experiments examining the structure of a steady state plume of hot and salty water that rises buoyantly near the source and descends as a fountain after it has cooled sufficiently. We call this a double-diffusive plume because its evolution is dictated by the different (turbulent) diffusivities of heat and salt. A temperature and conductivity probe measures both the salinity and temperature along the centreline of the plume. The supposed axisymmetric structure of the salinity concentration as it changes with height is determined by light-attenuation methods. To help interpret the results, a theory has been successfully adapted from the work of Bloomfield and Kerr (2000), who developed coupled equations describing the structure of fountains. Introducing a new empirical parameter for the relative rates of turbulent heat and salt diffusion, the predictions are found to agree favourably with experimental results.

Sutherland, Bruce; Lee, Brace

2008-11-01

181

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...

182

THE TREATMENT OF CONTAMINATED WATER AT REMEDIAL WOOD PRESERVING SITES  

EPA Science Inventory

Contaminated groundwater and surface water have posed a great challenge in restoring wood preserving sites to beneficial use. Often contaminated groundwater plumes extend far beyond the legal property limits, adversely impacting drinking water supplies and crop lands. To contain,...

183

Hotspots: Mantle Thermal Plumes  

NSDL National Science Digital Library

This article discusses the idea of 'hot spot' volcanoes, those not associated with plate tectonic boundaries, but rather with relatively stationary sources of heat energy (thermal plumes) in the mantle. Topics include the development of the theory by Canadian geophysicist J. Tuzo Wilson; the mechanics of volcanism over a hot spot as seen in the Hawaiian Islands; ancient Hawaiian observations of the ages of their islands; and the distribution of other hot spots around the world.

184

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

185

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

186

Ground-Water Capture Zone Delineation of Hypothetical Systems: Methodology Comparison and Real-World Applications  

Microsoft Academic Search

A capture zone is the aquifer volume through which ground-water flows to a pumping well over a given time of travel. Determining a well's capture zone aids in water-supply management by creating an awareness of the water source. This helps ensure sustainable pumping operations and outlines areas where protection from contamination is critical. We are delineating the capture zones of

J. A. Ahern; M. R. Lilly; L. D. Hinzman

2003-01-01

187

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

188

Estimation of Background Levels of Contaminants.  

National Technical Information Service (NTIS)

The chapter describes a statistical approach for assessing background levels from a dataset. These elevated values that may be associated with a plume or contaminated area of the site are separated from lower values that are assumed to represent backgroun...

A. Singh A. K. Singh G. Flatman

1994-01-01

189

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 ...

190

Volcanic eruption plumes on Io  

NASA Technical Reports Server (NTRS)

The nine eruption plumes observed by Voyager 1 are discussed. The plumes range in height from about 60 to over 300 km with corresponding ejection velocities of about 0.5 to 1.0 km/s. Plume sources are located on level plains rather than topographic highs and consist of either fissures or calderas. Except for Ple, the brightness distribution monotonically decreases from the core to the top of the plume. Numerous surface deposits similar to those associated with active plumes probably mark the sites of recent eruptions. The distribution of active and recent eruptions appears to be concentrated in the equatorial regions. This suggests that the depositional rate is greater and the surface age younger in the equatorial regions, possibly accounting for the active eruptions suggests that sulfur volcanism rather than silicate volcanism is the most likely driving mechanism for the eruption plumes.

Strom, R. G.; Schneider, N. M.

1982-01-01

191

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

192

Hele-Shaw Experiments on Plume Stretching and Folding  

NASA Astrophysics Data System (ADS)

Fluid mixing in laminar flow is important in a number of practical applications, including remediation of contaminated groundwater. Recent modeling studies have shown that mixing can be accelerated and amplified by imposing a flow that generates stretching and folding of an injected plume of treatment solution. Stretching and folding, in turn, results from engineered injection and extraction of clean water through an array of wells surrounding the treatment solution. This poster describes a series of experiments whose goal is to demonstrate plume stretching and folding in a Hele-Shaw apparatus. An initial plume of treatment solution is injected into the center of the Hele-Shaw apparatus, which is assumed to represent a zone of contaminated groundwater, with four wells spaced evenly around the treatment solution. In order to spread the treatment solution into the groundwater, the four wells perform a series of infusions and withdrawals that push and pull apart the plume of treatment solution. With the proper steps, it will be shown that the plume can be stretched and folded to greatly increase the reactive interface area between the treatment solution and the contaminated groundwater. Consideration is given to two qualitative differences with respect to previous modeling studies. First, constant volume is required by the no-flow boundary used at the edge of the Hele-Shaw cell; any pump that is withdrawing water must have a complementary pump adding water at the same rate. Second, in these experiments, mixing results from a physical process, namely Taylor dispersion, eliminating the uncertainty resulting from the need to assume dispersion mechanisms in numerical models. Therefore, these experiments further elucidate the benefits and challenges of imposing plume stretching and folding in systems (like aquifers) where dispersion is unavoidable, providing new insight into the required logistics of using this approach in groundwater treatment.

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

2013-12-01

193

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

194

Seismic Imaging of Mantle Plumes  

NASA Astrophysics Data System (ADS)

The mantle plume hypothesis was proposed thirty years ago by Jason Morgan to explain hotspot volcanoes such as Hawaii. A thermal diapir (or plume) rises from the thermal boundary layer at the base of the mantle and produces a chain of volcanoes as a plate moves on top of it. The idea is very attractive, but direct evidence for actual plumes is weak, and many questions remain unanswered. With the great improvement of seismic imagery in the past ten years, new prospects have arisen. Mantle plumes are expected to be rather narrow, and their detection by seismic techniques requires specific developments as well as dedicated field experiments. Regional travel-time tomography has provided good evidence for plumes in the upper mantle beneath a few hotspots (Yellowstone, Massif Central, Iceland). Beneath Hawaii and Iceland, the plume can be detected in the transition zone because it deflects the seismic discontinuities at 410 and 660 km depths. In the lower mantle, plumes are very difficult to detect, so specific methods have been worked out for this purpose. There are hints of a plume beneath the weak Bowie hotspot, as well as intriguing observations for Hawaii. Beneath Iceland, high-resolution tomography has just revealed a wide and meandering plume-like structure extending from the core-mantle boundary up to the surface. Among the many phenomena that seem to take place in the lowermost mantle (or D''), there are also signs there of the presence of plumes. In this article I review the main results obtained so far from these studies and discuss their implications for plume dynamics. Seismic imaging of mantle plumes is still in its infancy but should soon become a turbulent teenager.

Nataf, Henri-Claude

195

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

196

Enceladus Plume Composition (Invited)  

NASA Astrophysics Data System (ADS)

The Cassini-Huygens Ion Neutral Mass Spectrometer (Cassini INMS) has obtained valuable data on the composition and structure of the Enceladus plume on several flybys of the Cassini spacecraft: E3, E5, E7, E14, E17, and E18. Flybys E3, and E5 had flyby velocities of 16.6 and 17.7 km per second, respectively, due to the large inclination of the Cassini orbit plane with respect to the Saturn ecliptic plane, while flybys E7, E14, E17, and E18 performed a prograde equatorial flyby of Enceladus below the southern pole with flyby velocities of 7 to 8 km per second. The plume composition observed by the ion neutral mass spectrometer at the various flyby velocities was strongly dependent on the flyby velocity. In particular decreases in the water to molecular hydrogen density and the carbon dioxide to carbon monoxide ratios were observed as the flyby speed increased. We have investigated these changes using collisional models that can determine the effects of molecules and micron-sized ice grains as they impact the titanium surface of the closed ion source of the instrument. At flyby velocities above 16 km per second the subsequent release of titanium vapor induces chemical changes in the incoming gas. At all velocities some molecular fragmentation is possible. Using these model results we examine the velocity-induced changes during the various flybys. We find that water molecules can be converted to molecular hydrogen by chemi-absorption of the water onto the titanium vapor thus creating titanium oxide. However, changes induced in carbon dioxide and carbon monoxide cannot be explained by this process, but are likely due to molecular fragmentation of organic macromolecules. Organic macromolecules (dust grains) or organic macromolecules as condensation nuclei for ice grains can be dissociated by impact on the titanium surface and observed as molecular fragments in the mass spectra from the plume during high velocity flybys. These processes have important implications for the previously reported composition of the Enceladus plume, which are presented in this paper.

Waite, J. H.; Brockwell, T.; Magee, B.; Walker, J.; Chocron, S.; Lewis, W. S.; McKinnon, W. B.

2013-12-01

197

Plasmaspheric plumes: CRRES observations  

NASA Astrophysics Data System (ADS)

CRRES plasma wave receiver density data were used to study the distribution and properties of dense plasmaspheric-like plasma observed outside the plasmapause. Our study indicates that outer plasmaspheric structure, often called plasmaspheric plumes, blobs, or detached plasma regions exist at all local times under all levels of geomagnetic activity. Of the 549 CRRES orbits that had at least one clearly defined plasmapause, 201 (or 36.6%) had plasmaspheric-like density structures at higher L shells than the plasmapause. Most of the occurrence of plasmaspheric-like plasma observed by CRRES was in the noon-to-dusk sector and was observed following moderate geomagnetic activity.

Howard, J.; Moldwin, M. B.; Sanny, J.; Rassoul, H. K.; Anderson, R. R.

2003-12-01

198

Hyrogeology and Leachate Plume Delineation at a Closed Municipal Landfill, Norman, Oklahoma.  

National Technical Information Service (NTIS)

The City of Norman operated a solid-waste municipal landfill at two sites in the Canadian River alluvium in Cleveland County, Oklahoma from 1970 to 1985. The sites, referred to as the west and east cells of the landfill, were originally excavations in the...

C. J. Becker

2002-01-01

199

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

200

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

201

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.

von Glasow, Roland

2010-01-01

202

SULFATE FORMATION IN URBAN PLUMES  

EPA Science Inventory

In the concept of an 'urban plume', the combined air pollutants from several major emission sources in an urban area are considered to be carried, with air masses moving across the city, out over nonurban land or water. A plume may be distinguished from the unpolluted nonurban at...

203

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

204

Dispersion of a plume of tracer particles by bedload transport  

NASA Astrophysics Data System (ADS)

Particles entrained by rivers tend to disperse as they move downstream. Understanding the mechanisms responsible for particle dispersion is therefore important to describe the transport of solid-phase contaminants in streams or the accumulation of cosmogenic radionuclides in sediment grains during transport. While the prediction of the sediment transport rate at a specific point has been the topic of a large number of investigations, particle dispersion has however received much less attention. Here, we use the erosion-deposition model proposed by Lajeunesse et al. [2010] to understand the transport of a plume of tracer particles. We restrict our analysis to the case of steady-state transport above a flat bed of uniform sediment. We show that, at equilibrium, the transport of a plume of tracer particles obeys an advection-exchange mechanism. After a transient dominated by initial conditions, the transport of the plume tends toward an advection-diffusion equation.

Lajeunesse, Eric; Devauchelle, Olivier; Houssais, Morgane; Seizilles, Grégoire

2013-04-01

205

Bioremediation of contaminated groundwater  

DOEpatents

Disclosed is an apparatus and method for in situ remediation of contaminated subsurface soil or groundwater contaminated by chlorinated hydrocarbons. A nutrient fluid (NF) is selected to simulated the growth and reproduction of indigenous subsurface microorganisms capable of degrading the contaminants; an oxygenated fluid (OF) is selected to create an aerobic environment with anaerobic pockets. NF is injected periodically while OF is injected continuously and both are extracted so that both are drawn across the plume. NF 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 acceptable. NF can be methane and OF be air, for stimulating production of methanotrophs to break down chlorohydrocarbons, especially TCE and tetrachloroethylene.

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

1994-01-01

206

Automated basin delineation from digital terrain data  

NASA Technical Reports Server (NTRS)

While digital terrain grids are now in wide use, accurate delineation of drainage basins from these data is difficult to efficiently automate. A recursive order N solution to this problem is presented. The algorithm is fast because no point in the basin is checked more than once, and no points outside the basin are considered. Two applications for terrain analysis and one for remote sensing are given to illustrate the method, on a basin with high relief in the Sierra Nevada. This technique for automated basin delineation will enhance the utility of digital terrain analysis for hydrologic modeling and remote sensing.

Marks, D.; Dozier, J.; Frew, J.

1983-01-01

207

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...

208

Scanning thermal plumes  

NASA Technical Reports Server (NTRS)

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 of the velocity of thermal fronts are constructed by tracing the front motion in successive thermal images. A procedure is outlined for the two-point ground calibration of a thermal scanner from an equation describing the scanner signal and the voltage for two known temperatures. The modulation transfer function is then calculated by input of a thermal step function and application of digital time analysis techniques using Fast Fourier Transforms to the voltage output. Field calibration tests are discussed. Data accuracy is limited by the level of ground truth effort chosen.

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

1975-01-01

209

Complex electrical resistance tomography of a subsurface PCE plume  

SciTech Connect

A controlled experiment was conducted to evaluate the performance of complex electrical resistivity tomography (CERT) for detecting and delineating free product dense non-aqueous phase liquid (DNAPL) in the subsurface. One hundred ninety liters of PCE were released at a rate of 2 liters per hour from a point 0.5 m below ground surface. The spill was conducted within a double walled tank where saturated layers of sand, bentonite and a sand/bentonite mixture were installed. Complex electrical resistance measurements were performed. Data were taken before the release, several times during, and then after the PCE was released. Magnitude and phase were measured at 1 and 64 Hz. Data from before the release were compared with those during the release for the purpose of imaging the changes in conductivity resulting from the plume. Conductivity difference tomographs showed a decrease in electrical conductivity as the DNAPL penetrated the soil. A pancake-shaped anomaly developed on the top of a bentonite layer at 2 m depth. The anomaly grew in magnitude and extent during the release and borehole television surveys data confirmed the anomaly to be free-product PCE whose downward migration was stopped by the low permeability clay. The tomographs clearly delineated the plume as a resistive anomaly.

Ramirez, A.; Daily, W,; LeBrecque, D.

1996-01-01

210

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

211

Induced Contamination Predictions for JAXA's MPAC&SEED Devices  

NASA Technical Reports Server (NTRS)

Externally mounted ISS payloads are exposed to the induced ISS environment, including material outgassing and thruster plume contamination. The Boeing Space Environments Team developed analytical and semiempirical models to predict material outgassing and thruster plume induced contamination. JAXA s SM/MPAC&SEED experiment provides an unique opportunity to compare induced contamination predications with measurements. Analysis results are qualitatively consistent with XPS measurements. Calculated depth of contamination within a factor of 2-3 of measured contamination. Represents extremely good agreement, especially considering long duration of experiment and number of outgassing sources. Despite XPS limitations in quantifying plume contamination, the measured and predicted results are of similar scale for the wake-facing surfaces. JAXA s JEM/MPAC&SEED experiment will also be exposed to induced contamination due to JEM and ISS hardware. Predicted material outgassing induced contamination to JEM/MPAC&SEED ranges from 44 to 262 (depending on surface temperature) for a 3 year exposure duration.

Steagall, Courtney; Smith, Kendall; Huang, Alvin; Soares, Carlos; Mikatarian, Ron

2008-01-01

212

Delineation of Japanese soil temperature regime map  

Microsoft Academic Search

The soil temperature regime map provides for utilitarian classification that can be superimposed on soil classification to permit more precise interpretations and assessments of land use. The objects of this study are (1) to clarify the relationship between soil temperature and meteo-geographical factors, and then (2) to delineate detailed soil temperature regime map (1?km grid) as Japanese land resources inventory.

Yusuke Takata; Tsuneo Kuwagata; Kazunori Kohyama; Hiroshi Obara

2011-01-01

213

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

214

A simple method for calculating growth rates of petroleum hydrocarbon plumes.  

PubMed

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. PMID:16324003

Bekins, Barbara A; Cozzarelli, Isabelle M; Curtis, Gary P

2005-01-01

215

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

216

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...

217

Relating River Plume Structure to Vertical Mixing  

Microsoft Academic Search

The structure of a river plume is related to the vertical mixing using an isohaline-based coordinate system. Salinity coordinates offer the advantage of translating with the plume as it moves or expanding as the plume grows. This coordinate system is used to compare the relative importance of different dynamical processes acting within the plume and to describe the effect each

Robert D. Hetland

2005-01-01

218

On the transient nature of mantle plumes  

Microsoft Academic Search

We present new experiments focussing on the transient behaviour of thermal plumes. In a fluid heated from below, plumes develop once the hot thermal boundary layer (TBL) reaches a critical thickness (Howard, 1964). They rise through the fluid owing to their thermal buoyancy and comprise TBL material which empties itself into the plumes. As the TBL becomes exhausted, plumes start

Anne Davaille; Judith Vatteville

2005-01-01

219

Bubble plumes and the Coanda effect  

Microsoft Academic Search

This paper describes the mean gas fraction distribution in the two-phase flow of a gas–liquid bubble plume set to develop adjacent either to a wall or to another bubble plume. When this happens, the plume exhibits a type of Coanda effect, bending either towards the wall or the other plume. The local mean gas fraction measurements are carried out using

Atila P. Silva Freire; Davi D'E. Miranda; Leonardo M. S. Luz; Guilherme F. M. Franca

2002-01-01

220

Observations of cooling tower and stack plumes and their comparison with plume model "ALINA"  

NASA Astrophysics Data System (ADS)

Aircraft observations of stack and cooling tower plumes taken at a big power plant are compared with corresponding outputs of one-dimensional plume model ALINA, yielding certain improvements to the entrainment parametrization and dynamics of the model. Some observations of plume-plume and plume-environment interactions are reported.

Haman, Krzysztof E.; Malinowski, Szymon P.

221

Geodynamics: Mantle plume chemical diversity  

NASA Astrophysics Data System (ADS)

Ocean island lavas have complex geochemical signatures. Numerical simulations suggest that these signatures may reflect the entrainment and transport to Earth's surface of both primordial material and recycled oceanic crust by deeply rooted mantle plumes.

Deschamps, Frédéric

2014-05-01

222

Fluctuations in Atmospheric Boundary Layer Plumes  

NASA Astrophysics Data System (ADS)

Pollution and short-term health considerations require the accurate prediction of airborne contaminant transport in cities. Even when a stationary source emits tracer gases continuously, the resulting plume fluctuates vigorously in the turbulence that results from air passing over any typical landscape. Computing this flow properly requires large-eddy simulations that resolve the vortices shed from buildings, trees, and terrain because these coherent effects govern the ``turbulent'' dispersion of pollutants, tracer gases, and potentially toxic agents. This paper uses long-time, high-resolution detailed studies of one urban configuration, computed with 5-meter spatial resolution and sub-second temporal resolution, to quantify the deviations of passive tracer plumes from steady state. Even when concentration values at a point are averaged over long times, as an accumulating sensor might do, the range of probable values spans orders of magnitude. At a 5-km scale, averaging tracer concentrations for as long as an hour still leaves likely sampling fluctuations of plus or minus a factor of ten from the long-time average.

Boris, Jay; Fyfe, David; Obenschain, Miyoung; Obenschain, Keith; Patnaik, Gopal

2011-11-01

223

Superfund record of decision (EPA Region 1): Otis Air National Guard (containment of 7 groundwater plumes), Falmouth, MA, September 25, 1995  

SciTech Connect

The Massachusetts Military Reservation (MMR) on Cape Cod, Massachusettes lies within the boundaries of Bourne, Mashpee, and Sandwich, and abuts Falmouth. Seven groundwater contaminant plumes have migrated beyond or are approaching the installation boundary. This interim remedial action will intercept the contaminated groundwater plumes to prevent further downgradient movement of the contaminants. Extraction and treatment will continue until the final remedy for the site is chosen.

NONE

1996-03-01

224

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.

225

Superfund Record of Decision (EPA Region 9): Newmark Groundwater Contamination Site, San Bernardino, CA., August 1993.  

National Technical Information Service (NTIS)

This decision document presents the selected remedial action for the Newmark Operable Unit, Newmark Groundwater Contamination Superfund site. EPA has selected an interim remedy for the Newmark plume of groundwater contamination in the Newmark Groundwater ...

1993-01-01

226

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

227

Isotopic Diversity and Plume Strength  

NASA Astrophysics Data System (ADS)

The scale and geometry of isotopic heterogeneities in the source of plumes are poorly known but have important scientific implications for the origin of plumes, for the processes occurring during magma ascent through the mantle and for the timing of differentiation and mixing within the mantle. Isotopic heterogeneities occur at all scales in mantle rocks. Melt inclusions in mantle minerals have remarkably diverse isotopic compositions compared to their host lavas. At a much larger scale, the isotopic compositions of plume magmas are significantly different from ridge volcanics. Here we address the relationship between isotopic heterogeneity and magma productivity in mantle plumes. We compare several plumes, some very strong and long-lived like Hawaii and others very weak with sporadic magmatic activity. For the latter, we concentrate on the Polynesian Archipelago in the South Pacific which comprises several arrays of oceanic islands build over the past 20 Ma. We calculate, for several radiogenic isotopic systems, the isotopic amplitude within each island or island group and normalize these values to the total known variability in ocean island basalts worldwide. Our calculations show that isotopic diversity exists in all island groups, but where extreme isotopic compositions occur, they are always accompanied by FOZO-like compositions (the mean composition of all oceanic island). For example, the largest amplitudes for Pb isotopic compositions are found in the Austral chain where HIMU-type basalts erupt together with lavas with much lower Pb isotopes; and the largest amplitude for Nd isotopic compositions occurs in Pitcairn chain where EM I-type magmas coexist with lavas with much more radiogenic Nd isotopes. Additionally, our compilation shows that the isotopic diversity increases drastically as magma flux diminishes. We conclude that weak plumes selectively sample the source isotopic diversity through preferential low degree melting of small-scale heterogeneities. In contrast, strong plumes which produce large amounts of magma have much more homogeneous isotopic compositions as a consequence of efficient mixing of source heterogeneities during high-degree melting.

Chauvel, C.; Maury, R. C.; Gutscher, M.

2012-12-01

228

Evaluation of Concrete Median Barrier Delineation Under Poor Visibility Conditions.  

National Technical Information Service (NTIS)

In this research, a nationwide survey, durability test, and visibility test were conducted for concrete median barrier delineation. This research was in response to problems PENNDOT was encountering with delineators becoming detached due to harsh conditio...

L. J. French K. A. French

2002-01-01

229

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

230

Analysis of resistivity data obtained from cone penetrometer in contaminated soil layers  

NASA Astrophysics Data System (ADS)

In horizontally layered soils of different electrical properties, electrical potential distribution becomes complex and the obtained resistivity data may be limited in reflecting the actual soil profile. Thus the objective of this study was to identify the factors that affect resistivity measurement on the cone penetrometer and further investigate the sensitivity of measured resistivity to different types and concentrations of contaminants at the subsurface level. First, a theoretical resistivity equation was derived to provide a means of computing the geometric factor. The effective volume of measurement on the cone penetrometer was investigated and laboratory soil box tests verified the dominance of partially high resistivity regions within the effective volume of measurement over the apparent resistivity. Such effect was found to lead to possible discrepancies between the recorded resistivity data and the actual depth of measurement. Measurements on contaminated soil layers indicated that resistivity cones are efffective in delineating inorganic contaminants in soils of high water contents, and detecting NAPLs floating above the groundwater table provided that soils adjacent to the plume are not dry of water.

Kim, Yong Sung; Oh, Myoung Hak; Park, Junboum

2009-09-01

231

Enceladus's Plumes: A Rocket Analogy  

NASA Astrophysics Data System (ADS)

The plumes of Enceladus, and the source of the E-ring in the Saturnian system, easily rank as the major, significant, and unexpected discovery of the Cassini mission. While clearly the source of the E-ring,the nature of the sources and the energetics and dynamics of the plumes and underlying jets remains a subject of intensive study. Refinements of the observations suggest supersonic flow of the primary, water-vapor effluent. Such behavior implies a sonic critical point in the flow beginning from a heated reservoir of vapor, through a constriction, and out at supersonic speeds in the space above the plume/jet channels. Such geometry and thermal conditions mimic that of a de Laval nozzle, such as used in rocket engines for converting chemically heated combustion products into a directional flow. A chamber temperature of 180K suggests an outflow speed as high as 0.8 km/s. With a column density across a jet of ~3 x 1016 cm-2 (about twice that of the broad plume) and a jet width of ~10 km, the implied outflow of water molecules is ~3 x 1010 cm-3 x ?/4 (106 cm)2 x 18 amu x 1.66 x 10-27 amu/kg x 8 x 104 cm/s = ~60 kg/s in each constituent jet, of which eight were identified by the Cassini Ultraviolet Imaging Spectrograph (UVIS) during the occultation measurements of the plume region of Enceladus carried out on 24 October 2007.

McNutt, R. L.; Perry, M. E.; Waite, J. H.; Fletcher, G.; Cravens, T. E.

2009-12-01

232

High-altitude plume computer code development  

NASA Technical Reports Server (NTRS)

The flowfield codes that have been developed to predict rocket motor plumes at high altitude were used to predict plume properties for the RCS motor which show reasonable agreement with experimental data. A systematic technique was established for the calculation of high altitude plumes. The communication of data between the computer codes was standardized. It is recommended that these outlined procedures be more completed, documented and updated as the plume methodology is applied to the varied problems of plume flow and plume impingement encountered by space station design and operation.

Audeh, B. J.; Murphy, J. E.

1985-01-01

233

INDEPENDENT TECHNICAL REVIEW OF THE FOCUSED FEASIBILITY STUDY AND PROPOSED PLAN FOR DESIGNATED SOLID WASTE MANAGEMENT UNITS CONTRIBUTING TO THE SOUTHWEST GROUNDWATER PLUME AT THE PADUCAH GASEOUS DIFFUSION PLANT  

Microsoft Academic Search

The U. S. Department of Energy (DOE) is currently developing a Proposed Plan (PP) for remediation of designated sources of chlorinated solvents that contribute contamination to the Southwest (SW) Groundwater Plume at the Paducah Gaseous Diffusion Plant (PGDP), in Paducah, KY. The principal contaminants in the SW Plume are trichloroethene (TCE) and other volatile organic compounds (VOCs); these industrial solvents

B. Looney; C. Eddy-Dilek; M. Amidon; J. Rossabi; L. Stewart

2011-01-01

234

Influence Of Groundwater Discharge On Arsenic Contamination In Sediments  

EPA Science Inventory

A field investigation was conducted to evaluate the impact of a discharging arsenic plume on sediment contaminant characteristics at a site adjacent to a landfill in northeastern Massachusetts. Site characterization included assessment of the hydrologic and chemical samples coll...

235

Gaseous Behavior of TCE (Trichloroethylene) Overlying a Contaminated Aquifer.  

National Technical Information Service (NTIS)

Shallow soil gas (<2 meters deep) was collected and analyzed for trichloroethylene (TCE) to determine the relationship with ground-water contamination directly below. The gaseous TCE plume was mapped with 46 probes and spanned three orders of magnitude in...

D. L. Marrin G. M. Thompson

1987-01-01

236

Photoelectrons in the Enceladus plume  

NASA Astrophysics Data System (ADS)

The plume of Enceladus is a remarkable plasma environment containing several charged particle species. These include cold magnetospheric electrons, negative and positive water clusters, charged nanograins, and "magnetospheric photoelectrons" produced from ionization of neutrals throughout the magnetosphere near Enceladus. Here we discuss observations of a population newly identified by the Cassini Plasma Spectrometer (CAPS) electron spectrometer instrument—photoelectrons produced in the plume ionosphere itself. These were found during the E19 encounter, in the energetic particle shadow where penetrating particles are absent. Throughout E19, CAPS was oriented away from the ram direction where the clusters and nanograins are observed during other encounters. Plume photoelectrons are also clearly observed during the E9 encounter and are also seen at all other Enceladus encounters where electron spectra are available. This new population, warmer than the ambient plasma population, is distinct from, but adds to, the magnetospheric photoelectrons. Here we discuss the observations and examine the implications, including the ionization source these electrons provide.

Coates, A. J.; Wellbrock, A.; Jones, G. H.; Waite, J. H.; Schippers, P.; Thomsen, M. F.; Arridge, C. S.; Tokar, R. L.

2013-08-01

237

Delineating bird populations using ring recoveries  

USGS Publications Warehouse

We delineate bird populations using cluster analysis to group ringing sites based on pairwise comparisons of recoveries. Clustering provides a quantitative (but non-unique) grouping that can be used to examine the relationships of bird distributions at both local and regional geographic scales. Clustering is based on similarity matrices composed of pairwise comparisons of recovery distributions from ringing sites. We demonstrate the method using mallard (Anas platyrhynchos) ring recoveries to group ringing sites in south-central Canada, and discuss the possibilities for these analyses for non-hunted species with few recoveries.

Pendleton, G.W.; Sauer, J.R.

1995-01-01

238

Assessment of Soil-Gas and Soil Contamination at the Old Metal Workshop Hog Farm Area, Fort Gordon, Georgia, 2009-2010.  

National Technical Information Service (NTIS)

Soil gas and soil were assessed for contaminants at the Old Metal Workshop Hog Farm Area at Fort Gordon, Georgia, from October 2009 to September 2010. The assessment included delineating organic contaminants present in soil-gas and inorganic contaminants ...

A. W. Caldwell J. B. Wellborn J. E. Landmeyer W. B. Guimaraes W. F. Falls W. H. Ratliff

2011-01-01

239

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

240

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

241

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

242

Lithosphere erosion atop mantle plumes  

NASA Astrophysics Data System (ADS)

Mantle plumes are traditionally proposed to play an important role in lithosphere erosion. Seismic images beneath Hawaii and Cape Verde show a lithosphere-asthenosphere-boundary (LAB) up to 50 km shallower than the surroundings. However, numerical models show that unless the plate is stationary the thermo-mechanical erosion of the lithosphere does not exceed 30 km. We use 2D petrological-thermo-mechanical numerical models based on a finite-difference method on a staggered grid and marker in cell method to study the role of partial melting on the plume-lithosphere interaction. A homogeneous peridotite composition with a Newtonian temperature- and pressure-dependent viscosity is used to simulate both the plate and the convective mantle. A constant velocity, ranging from 5 to 12.5 cm/yr, is imposed at the top of the plate. Plumes are created by imposing a thermal anomaly of 150 to 350 K on a 50 km wide domain at the base of the model (700 km depth); the plate right above the thermal anomaly is 40 Myr old. Partial melting is modeled using batch-melting solidus and liquidus in anhydrous conditions. We model the progressive depletion of peridotite and its effect on partial melting by assuming that the melting degree only strictly increases through time. Melt is accumulated until a porosity threshold is reached and the melt in excess is then extracted. The rheology of the partially molten peridotite is determined using viscous constitutive relationship based on a contiguity model, which enables to take into account the effects of grain-scale melt distribution. Above a threshold of 1%, melt is instantaneously extracted. The density varies as a function of partial melting degree and extraction. Besides, we analyze the kinematics of the plume as it impacts a moving plate, the dynamics of time-dependent small-scale convection (SSC) instabilities developing in the low-viscosity layer formed by spreading of hot plume material at the lithosphere base, and the resulting thermal rejuvenation of the lithosphere. The onset time and the vigor of SSC and, hence, the new equilibrium thermal state of the lithosphere atop the plume wake depends on the Rayleigh number (Ra) in the unstable layer at the base of the lithosphere, which is controlled by the temperature anomaly and rheology in the plume-fed layer. For vigorous, hot plumes, SSC onset times do not depend on plate velocity. For more sluggish plumes, SSC onset times decrease with increasing plate velocity. This behavior is explained by differences in the thermal structure of the lithosphere, due to variations in the spreading behavior of the plume material at the lithosphere base. Reduction of the viscosity in partial molten areas and decrease in density of the depleted residuum enhance the vigor of small-scale convection in the plume-fed low-viscosity layer at the lithosphere base, leading to more effective erosion of the base of the lithosphere.

Agrusta, R.; Arcay, D.; Tommasi, A.

2012-12-01

243

AXAIR and PUFF-PLUME Comparison  

SciTech Connect

A test version of AXAIR has been prepared to compare with PUFF-PLUME. The test version of AXAIR applies the same meteorological conditions as PUFF-PLUME and also the dispersion coefficients have been changed to be the same as those in PUFF-PLUME. The test version of AXAIR and PUFF-PLUME produce virtually the same doses with the differences being less than 3% for the select cases with similar input. Differences and similarities in the models are also addressed.

Simpkins, A.A.; Kurzeja, R.J.

1995-09-28

244

Evaluation of a Chlorinated Compounds Plume in a Fractured Sandstone Aquifer in Mid- West, US  

NASA Astrophysics Data System (ADS)

A study was carried out in the sedimentary fractured rock site located in Mid West, US, which was impacted by a DNAPL spill estimated to occur in the 1950's and 1960's. The majority of the DNAPL has accumulated in the upper portion of the Lone Rock Formation (referred to as Layer 5) and a VOC plume of more than 3km long has formed. The DNAPL is mainly composed of 1,1,1-TCA, PCE, TCE and BTEX, while large amounts of degradation products such as cis-DCE and 1,1-DCA have been found in the plume. Detailed geochemical and carbon isotope analysis in September 2007 showed that complete degradation of PCE and TCE to cis-DCE in Layer 5 had been achieved from the source to the middle of the plume and the dechlorination reaction stalled at cis-DCE, which is in agreement with the redox condition in this part of the plume. On the other hand, degradation of 1,1,1-TCA to 1,1-DCA was incomplete. The fringes of the plume are characterized by the presence of PCE and TCE in agreement with aerobic conditions in this part of the plume. A historical data review from 1992 to 2006 revealed two phases of degradation in Layer 5. The first phase corresponded with the period before 2001, when there was no significant degradation, while the second phase corresponded with the period after 2001, when significant degradation occurred. The occurrence of the second phase was related to a large scale DNAPL pumping in the source zone during 1999 to 2002, which caused a great increase of contaminant concentrations in the plume including large amounts of ketones and BTEX serving as electron donors and substrates for microbial dechlorination. Thus, subsequent degradation of chlorinated compounds occurred extensively in the plume. The contaminant concentration and the shape of the plume has been modified since 2003 by a hydraulic barrier system. This case study shows that the long term degradation pattern and contaminant distribution at the site has been controlled by plume management practices including DNAPL pumping in the source area and the creation of a hydraulic barrier system in the middle of the plume.

Miao, Z.; Aravena, R.; Parker, B. L.; Cherry, J. A.; Meyer, J. R.; Hunkeler, D.

2009-05-01

245

Plumes with non-monotonic mixing behaviour  

Microsoft Academic Search

We develop a model for the behaviour of continuous releases (plumes) of fluid which, upon mixing with the ambient fluid, undergo a non-monotonic change in density. This model serves as an analogue for the behaviour of volcanic eruption clouds and hydrothermal plumes. If, at the source, the plume is initially actually a negatively buoyant jet, but has the potential on

Colm-Cille P. Caulfield; Andrew W. Woods

1995-01-01

246

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

247

NRL Satellite Volcanic Ash Plume Monitoring  

Microsoft Academic Search

The Naval Research Laboratory's (NRL) Marine Meteorology Division (NRL-MRY) is assembling a unique suite of near real-time digital satellite products geared towards monitoring volcanic ash plumes which can create hazardous aviation conditions. Ash plume detection, areal extent, plume top height and mass loading will be extracted via automated algorithms from a combination of geostationary (GEO) and low earth orbiting (LEO)

J. Hawkins; A. P. Kuciauskas; K. Richardson; J. Solbrig; S. D. Miller; M. J. Pavolonis; R. Bankert; T. Lee; J. Kent; T. Tsui

2009-01-01

248

Types of thermal plumes in coastal waters  

NASA Technical Reports Server (NTRS)

A large number of thermal images of the surface temperatures of the thermal plumes associated with the once-through cooling of electric power plants show that four kinds of plume occur sufficiently often to be classified as distinct plume types. Each type has implications for both numerical models and measurement strategies.

Green, T.; Madding, R.; Scarpace, F.

1977-01-01

249

The ozone increments in urban plumes  

Microsoft Academic Search

The role of urban plumes in the exposure of suburban\\/rural areas to pollution by ozone is discussed, and literature on direct measurement of ozone within plumes reviewed. There is a virtual absence of reports of ozone destruction within a NOx-rich urban plume and reasons are given for this gap in the current published data. These negative ozone increments are important

A. R. MacKenzie; R. M. Harrison; I. Colbeck; P. A. Clark; R. H. Varey

1995-01-01

250

Plume mechanics and stratocumulus convection  

NASA Technical Reports Server (NTRS)

The First ISCCP Regional Experiment (FIRE) marine stratocumulus Intensive Field Observation (IFO) held in July, 1987 produced a data set that is far more comprehensive than data sets from previous stratocumulus experiments. One exciting new development was the use of the 10.6 micron lidar system for cloud-top mapping that was available on the National Center for Atmospheric Research (NCAR) Electra. This system provided a unique look at the small scales of the turbulence in the clouds, images of the turbulent structures that are quantitatively revealed by conditional sampling (e.g., Khalsa and Greenhut, 1987). The behavior of these updrafts and downdrafts is central to the dynamics of the stratocumulus-topped marine boundary layer. FIRE's objectives of understanding cloud dynamics and how they affect the cloud optical depth - which, in turn, is the crucial factor in determining the clouds' albedo - therefore require the investigation of these drafts. Given here are initial results from a simple model capable of simulating moist, entraining plumes that are subject to water phase changes and radiative heating and cooling. These results correspond, therefore, to the 'dry cloud' case discussed by Lilly and Schubert (1980). The model's simplicity limits the realism of the results - the plumes are assumed not to interact, for example - but the role of radiative processes in influencing the plume dynamics is clear. Also revealed is the role the plumes play is maintaining the cloud-top inversion. The model equations and methodology used, and qualitative results are given.

Hanson, Howard P.

1990-01-01

251

Superfund record of decision (EPA Region 4): Paducah Gaseous Diffusion Plant, Northwest Plume, Paducah, KY, July 1993  

SciTech Connect

This decision document presents the selected remedial action for the Northwest Plume at the Paducah Gaseous Diffusion Plant (PGDP) in Paducah, Kentucky. The primary objective of this interim remedial action is to initiate a first phase remedial action, as an interim action to initiate control of the source and mitigate the spread of contamination in the Northwest plume. This operable unit addresses a portion of the contaminated ground water. Additional interim actions associated with this integrator operable unit are being considered, as well as for other areas of contaminated ground water.

Not Available

1993-07-01

252

Real-time turbulent plume estimation with mobile sensors  

NASA Astrophysics Data System (ADS)

Ensemble methods for estimating turbulent fluid systems are efficient methods for quantifying uncertainties in nonlinear, high-dimensional systems. Many real-time estimation algorithms for large-scale fluid systems have been tested and validated by the weather/oceanic forecasting communities, but (generally speaking) these methods have not been used for short time-scale and short length-scale models. We present estimation results for a contaminant plume release experiment. In this experiment, a passive scaler is released at a known location in a small domain and a turbulent environment. Mobile robots are deployed to measure wind velocity and plume concentration. Measurements are assimilated to estimate the wind field and quantify the uncertainty in the estimate, which is then used to plan waypoints for future measurements.

Bewley, Thomas; Colburn, Christopher; Zhang, David; Cessna, Joseph; Morozovsky, Nicholas; Cavender, Andrew; Schmidt-Wetekam, Christopher

2010-11-01

253

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

254

A young source for the Hawaiian plume.  

PubMed

Recycling of oceanic crust through subduction, mantle upwelling, and remelting in mantle plumes is a widely accepted mechanism to explain ocean island volcanism. The timescale of this recycling is important to our understanding of mantle circulation rates. Correlations of uranogenic lead isotopes in lavas from ocean islands such as Hawaii or Iceland, when interpreted as model isochrons, have yielded source differentiation ages between 1 and 2.5?billion years (Gyr). However, if such correlations are produced by mixing of unrelated mantle components they will have no direct age significance. Re-Os decay model ages take into account the mixing of sources with different histories, but they depend on the assumed initial Re/Os ratio of the subducted crust, which is poorly constrained because of the high mobility of rhenium during subduction. Here we report the first data on (87)Sr/(86)Sr ratios for 138 melt inclusions in olivine phenocrysts from lavas of Mauna Loa shield volcano, Hawaii, indicating enormous mantle source heterogeneity. We show that highly radiogenic strontium in severely rubidium-depleted melt inclusions matches the isotopic composition of 200-650-Myr-old sea water. We infer that such sea water must have contaminated the Mauna Loa source rock, before subduction, imparting a unique 'time stamp' on this source. Small amounts of seawater-derived strontium in plume sources may be common but can be identified clearly only in ultra-depleted melts originating from generally highly (incompatible-element) depleted source components. The presence of 200-650-Myr-old oceanic crust in the source of Hawaiian lavas implies a timescale of general mantle circulation with an average rate of about 2 (±1)?cm?yr(-1), much faster than previously thought. PMID:21832996

Sobolev, Alexander V; Hofmann, Albrecht W; Jochum, Klaus Peter; Kuzmin, Dmitry V; Stoll, Brigitte

2011-08-25

255

Biogeochemical characterisation of a coal tar distillate plume  

NASA Astrophysics Data System (ADS)

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.

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

2001-12-01

256

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.

257

Dynamics of volcanic plumes on Io  

NASA Technical Reports Server (NTRS)

Ballistic and aerodynamic models are proposed to explain the dynamics of the volcanic plumes on Io. A ballistic model, which assumes that eruptive gas and solid-particle flows become completely and permanently decoupled over a small distance as compared with the maximum particle height, is shown to be unable to account for the observed shape of Plume 3. An aerodynamic model which assumes the entrainment and transportation of solid particles by the gas flow into the central portion of the top of the plume, with ballistic particle trajectories only after passage through the first part of their descent, is then developed. The model accounts for plume shape by the formation of a weak decompression shock near the edge of the plume stalk, which constrains horizontal expansion until a sufficient altitude is reached. Calculated plume dimensions are then compared with observations of Ionian Plumes 1 and 3.

Cook, A. F.; Shoemaker, E. M.; Smith, B. A.

1979-01-01

258

The plasma plumes of Europa and Callisto  

NASA Astrophysics Data System (ADS)

We investigate the proposition that Europa and Callisto emit plasma plumes, i.e., a contiguous body of ionospheric plasma, extended in the direction of the corotation flow, analogous to the plume of smoke emitted in the downwind direction from a smokestack. Such plumes were seen by Voyager 1 to be emitted by Titan. We find support for this proposition in published data from Galileo Plasma Science and Plasma Wave observations taken in the corotation wakes of both moons and from magnetometer measurements reported from near the orbit of, but away from, Europa itself. This lends credence to the hypothesis that the plumes escaping from the ionospheres of Europa and Callisto are wrapped around Jupiter by corotation, survive against dispersion for a fairly long time and are convected radially by magnetospheric motions. We present simple models of plume acceleration and compare the plumes of the Europa and Callisto to the known plumes of Titan.

Eviatar, Aharon; Paranicas, Chris

2005-11-01

259

SO2 depletion in tropospheric volcanic plumes  

NASA Astrophysics Data System (ADS)

Ground based remote sensing techniques are used to measure volcanic SO2 fluxes in efforts to characterise volcanic activity. As these measurements are made several km from source there is the potential for in-plume chemical transformation of SO2 to sulphate aerosol (conversion rates are dependent on meteorological conditions), complicating interpretation of observed SO2 flux trends. In contrast to anthropogenic plumes, SO2 lifetimes are poorly constrained for tropospheric volcanic plumes, where the few previous loss rate estimates vary widely (from $\\ll$1 to >99% per hour). We report experiments conducted on the boundary layer plume of Masaya volcano, Nicaragua during the dry season. We found that SO2 fluxes showed negligible variation with plume age or diurnal variations in temperature, relative humidity and insolation, providing confirmation that remote SO2 flux measurements (typically of ~500-2000 s old plumes) are reliable proxies for source emissions for ash free tropospheric plumes not emitted into cloud or fog.

McGonigle, A. J. S.; Delmelle, P.; Oppenheimer, C.; Tsanev, V. I.; Delfosse, T.; Williams-Jones, G.; Horton, K.; Mather, T. A.

2004-07-01

260

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

261

COMPLETE NATURAL ATTENUATION OF A PCE AND TCE PLUME AFTER SOURCE REMOVAL  

EPA Science Inventory

Disposal of the chlorinated solvents PCE and TCE at the Twin Cities Army Ammunition Plant (TCAAP) resulted in the contamination of groundwater in a shallow, unconsolidated sand aquifer. The resulting plume had moved over 1000 feet from the disposal source area and had impacted p...

262

Optimal design of pump-and-treat systems under uncertain hydraulic conductivity and plume distribution.  

PubMed

In this work, we present a stochastic optimal control framework for assisting the management of the cleanup by pump-and-treat of polluted shallow aquifers. In the problem being investigated, hydraulic conductivity distribution and dissolved contaminant plume location are considered as the uncertain variables. The framework considers the subdivision of the cleanup horizon in a number of stress periods over which the pumping policy implemented until that stage is dynamically adjusted based upon new information that has become available in the previous stages. In particular, by following a geostatistical approach, 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 pump-and-treat 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 measurements 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. PMID:18635286

Baú, Domenico A; Mayer, Alex S

2008-08-20

263

AN ANALYSIS OF THE ACTUAL THERMAL PLUMES OF KITCHEN APPLIANCES DURING COOKING MODE  

Microsoft Academic Search

The main purpose in the design practice of kitchen ventilation has been the calculation of the airflow rate, which is sufficient to extract the convective heat and contaminants. In the most accurate design method, the design of a kitchen ventilation system is based on the air flow rate in the thermal plume. When the convection flow is calculated, the influence

R Kosonen; H Koskela; P Saarinen

264

Intrinsic bioremediation of a BTEX and MTBE plume under mixed aerobic\\/denitrifying conditions  

Microsoft Academic Search

A shallow Coastal Plain aquifer in rural Sampson Country, North Carolina, has been contaminated with petroleum hydrocarbon from a leaking underground storage tank containing gasoline.An extensive field characterization has been performed to define the horizontal and vertical distribution of soluble gasoline components and indicator parameters. A plume of dissolved methyl tert-butyl ether (MTBE) and the aromatic hydrocarbons benzene, toluene, ethylbenzene,

R. C. Borden; R. A. Daniel

1995-01-01

265

Geophysical Characterization and Reactive Transport Modeling to Quantify Plume Behavior  

NASA Astrophysics Data System (ADS)

Predictions of subsurface contaminant plume mobility and remediation often fail due to the inability to tractably characterize heterogeneous flow-and-transport properties and monitor critical geochemical transitions over plume-relevant scales. This study presents two recently developed strategies to quantify and predict states and processes across scales that govern plume behavior. Development of both strategies takes advantage of multi-scale and disparate datasets and has involved the use of reactive transport models, geophysical methods, and stochastic integration approaches. The first approach, called reactive facies, exploits coupled physiochemical heterogeneity to characterize subsurface flow and transport properties that impact plume sorption and thus mobility. We develop and test the reactive facies concept within uranium contaminated Atlantic Coastal Plain sediments that underlie the U.S. Department of Energy Savannah River Site, F-Area, South Carolina. Through analysis of field data (core samples, geophysical well logs, and cross-hole ground penetrating radar and seismic datasets) coupled with laboratory sorption studies, we have identified two reactive facies that have unique distributions of mineralogy, texture, porosity, hydraulic conductivity and geophysical attributes. We develop and use facies-based relationships with geophysical data in a Bayesian framework to spatially distribute reactive facies and their associated transport properties and uncertainties along local and plume-scale geophysical transects. To illustrate the value of reactive facies, we used the geophysically-obtained reactive facies properties to parameterize reactive transport models and simulate the migration of an acidic-U(VI) plume through the 2D domains. Modeling results suggest that each identified reactive facies exerts control on plume evolution, highlighting the usefulness of the reactive facies concept and approach for spatially distributing properties that control flow and transport over field-relevant scales as is needed for predicting the plume behavior. The second approach focuses on identifying diagnostic signatures of critical system transitions. We develop a data-driven statistical approach in which we assume the biogeochemical process can be classified into several states that can be characterized using Hidden Markov models. We use a Bayesian approach to estimate the probability of being in each state over time and space by conditioning to the time-series of the measured borehole geochemical data and geophysical time-lapse data. We apply the developed method to the Rifle DOE field study site using data collected during a bioremediation experiment (including time-lapse surface spectral induced polarization data) to estimate critical redox transitions that influence uranium mobility. We compare the complementary nature of the data-driven approach with mechanistic reactive transport models in understanding and predicting critical system transitions and as a step towards development of autonomous monitoring and assimilation approaches needed to assess long-term plume behavior.

Hubbard, S. S.; Wainwright, H.; Bea, S. A.; Spycher, N.; Li, L.; Sassen, D.; Chen, J.

2012-12-01

266

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

267

Wellhead protection area delineation under uncertainty.  

National Technical Information Service (NTIS)

A program to protect groundwater resources used for water supply from all potential threats due to contamination was established in the Amendments to the Safe Drinking Water Act (SDWA). The goal of the State Wellhead Protection (WHP) Program is to 'protec...

E. Jacobson R. Andricevic T. Hultin

1994-01-01

268

Simultaneous multi-modality ROI delineation in clinical practice.  

PubMed

The delineation of tumors and their surrounding organs at risk is a critical step of the treatment planning for radiation therapy. Besides computer tomography (CT), other imaging modalities are used to improve the quality of the delineations, such as magnetic resonance imaging (MRI) and positron emission tomography (PET). A practical framework is presented for using multiple datasets from different modalities during the delineation phase. The system is based on two basic principles. First, all image datasets of all available modalities are displayed in their original form (in their own coordinate system, with their own spatial resolution and voxel aspect ratio), and second, delineations can take place on all orthogonal views of each dataset and changes made to a delineation are visualized in all image sets, giving direct feedback to the delineator. The major difference between the described approach and other existing delineation tools is that instead of resampling the image sets, the delineations are transformed from one dataset to another. The transformation used for transferring the delineations is obtained by rigid normalized mutual information registration. The crucial components and the benefits of the application are presented and discussed. PMID:19443076

Bol, Gijsbert H; Kotte, Alexis N T J; van der Heide, Uulke A; Lagendijk, Jan J W

2009-11-01

269

Swarms for chemical plume tracing  

Microsoft Academic Search

This paper presents a physics-based framework for managing distributed sensor networks of autonomous vehicles, e.g., robots, which self-organize into structured lattice arrangements using only local information. The vehicles remain in formation during obstacle avoidance and search for a chemical emitter that is actively ejecting a toxic chemical into the air. We discuss a new plume tracing algorithm, based on the

Dimitri Zarzhitsky; Diana F. Spears; William M. Spears

2005-01-01

270

Irritants in cigarette smoke plumes.  

PubMed Central

Concentrations of the irritants formaldehyde and acrolein in side stream cigarette smoke plumes are up to three orders of magnitude above occupational limits, readily accounting for eye and nasal irritation. "Low-tar" cigarettes appear at least as irritating as other cigarettes. More than half the irritant is associated with the particulate phase of the smoke, permitting deposition throughout the entire respiratory tract and raising the issue of whether formaldehyde in smoke is associated with bronchial cancer.

Ayer, H E; Yeager, D W

1982-01-01

271

Delineation of Borrelia burgdorferi sensu lato species by multilocus sequence analysis and confirmation of the delineation of Borrelia spielmanii  

Microsoft Academic Search

Abstract To evaluate multilocus sequence analysis (MLSA) for taxonomic,purposes in the delineation of species within Borrelia burgdorferi sensu lato, we sequenced seven relevant loci of various strains for which extensive DNA-DNA reassociation data were available. MLSA delineation proved to be fully concordant with conventional methods. Our analysis confirms the delineation of Borrelia spielmanii with the type strain PC-Eq17, and, thereby,

Dania Richter; Danièle Postic; Natacha Sertour; Ian Livey; Franz-Rainer Matuschka; Guy Baranton

2005-01-01

272

Modeling of Lunar Dust Contamination Due to Plume Impingement  

Microsoft Academic Search

Historical data from the Apollo missions indicate the ubiquitous presence of lunar dust caused a number of troubling performance issues, including degradation of mechanisms, optical elements, and thermal control devices. Consequently, NASA Constellation program managers are interested in developing designs, techniques, and procedures to mitigate the deleterious effects of this material when humans return to the Moon. One particular scenario

Michael Woronowicz

273

SURFACE AND BOREHOLE ELECTROMAGNETIC IMAGING OF CONDUCTING CONTAMINANT PLUMES  

EPA Science Inventory

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 ma...

274

COMPARISON OF PREDICTED AND OBSERVED PLUME TRENDS AT CONTAMINATED SITES  

EPA Science Inventory

Over 45 natural attenuation treatability studies (TSs) were performed from 1993 to 1999 by Parsons Corporation (Parsons) for the Technology Transfer Division of the Air Force Center for Environmental Excellence (AFCEE/ERT) in conjunction with researchers from the US EPA - NRMRL. ...

275

Mantle plumes on Venus revisited  

NASA Technical Reports Server (NTRS)

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.

1992-01-01

276

Microbial reduction of sulfate injected to gas condensate plumes in cold groundwater.  

PubMed

Despite a rapid expansion over the past decade in the reliance on intrinsic bioremediation to remediate petroleum hydrocarbon plumes in groundwater, significant research gaps remain. Although it has been demonstrated that bacterial sulfate reduction can be a key electron accepting process in many petroleum plumes, little is known about the rate of this reduction process in plumes derived from crude oil and gas condensates at cold-climate sites (mean temperature <10 degrees C), and in complex hydrogeological settings such as silt/clay aquitards. In this field study, sulfate was injected into groundwater contaminated by gas condensate plumes at two petroleum sites in Alberta, Canada to enhance in-situ bioremediation. In both cases the groundwater near the water table had low temperature (6-9 degrees C). Monitoring data had provided strong evidence that bacterial sulfate reduction was a key terminal electron accepting process (TEAP) in the natural attenuation of dissolved hydrocarbons at these sites. At each site, water with approximately 2000 mg/L sulfate and a bromide tracer was injected into a low-sulfate zone within a condensate-contaminant plume. Monitoring data collected over several months yielded conservative estimates for sulfate reduction rates based on zero-order kinetics (4-6 mg/L per day) or first-order kinetics (0.003 and 0.01 day(-1)). These results favor the applicability of in-situ bioremediation techniques in this region, under natural conditions or with enhancement via sulfate injection. PMID:17292997

Van Stempvoort, Dale R; Armstrong, James; Mayer, Bernhard

2007-07-17

277

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

278

Edge-Guided Boundary Delineation in Prostate Ultrasound Images  

Microsoft Academic Search

Accurate detection of prostate boundaries is required in many diagnostic and treatment procedures for prostate disease. Here, a new paradigm for guided edge delineation is described, a which involves presenting automatically detected prostate edges as a visual guide to the observer, followed by manual editing. This approach enables robust delineation of the prostate boundaries, making it suitable for routine clinical

Sayan D. Pathak; Vikram Chalana; David R. Haynor; Yongmin Kim

2000-01-01

279

Identification of an ancient mantle reservoir and young recycled materials in the source region of a young mantle plume: Implications for potential linkages between plume and plate tectonics  

NASA Astrophysics Data System (ADS)

Whether or not mantle plumes and plate subduction are genetically linked is a fundamental geoscience question that impinges on our understanding of how the Earth works. Late Cenozoic basalts in Southeast Asia are globally unique in relation to this question because they occur above a seismically detected thermal plume adjacent to deep subducted slabs. In this study, we present new Pb, Sr, Nd, and Os isotope data for the Hainan flood basalts. Together with a compilation of published results, our work shows that less contaminated basaltic samples from the synchronous basaltic eruptions in Hainan-Leizhou peninsula, the Indochina peninsula and the South China Sea seamounts share the same isotopic and geochemical characteristics. They have FOZO-like Sr, Nd, and Pb isotopic compositions (the dominant lower mantle component). These basalts have primitive Pb isotopic compositions that lie on, or very close to, 4.5- to 4.4-Ga geochrons on 207Pb/204Pb versus 206Pb/204Pb diagram, suggesting a mantle source developed early in Earth's history (4.5-4.4 Ga). Furthermore, our detailed geochemical and Sr, Nd, Pb and Os isotopic analyses suggest the presence of 0.5-0.2 Ga recycled components in the late Cenozoic Hainan plume basalts. This implies a mantle circulation rate of >1 cm/yr, which is similar to that of previous estimates for the Hawaiian mantle plume. The identification of the ancient mantle reservoir and young recycled materials in the source region of these synchronous basalts is consistent with the seismically detected lower mantle-rooted Hainan plume that is adjacent to deep subducted slab-like seismic structures just above the core-mantle boundary. We speculate that the continued deep subduction and the presence of a dense segregated basaltic layer may have triggered the plume to rise from the thermal-chemical pile. This work therefore suggests a dynamic linkage between deep subduction and mantle plume generation.

Wang, Xuan-Ce; Li, Zheng-Xiang; Li, Xian-Hua; Li, Jie; Xu, Yi-Gang; Li, Xiang-Hui

2013-09-01

280

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

281

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

282

Astrium Approach for Plume Flow and Impingement of 10 N Bipropellant Thruster  

NASA Astrophysics Data System (ADS)

Plume impingement on spacecraft surfaces due to chemical propulsion is a major concern during satellite operations. Indeed, thrusters plume induces disturbing forces and torques, contamination as well as thermal fluxes on sensitive surfaces. These effects, that have to be accurately predicted, influence the satellite design: thrusters orientation, MLI design, instruments protections, etc. In order to implement an efficient process of analysis, Astrium uses a two steps approach: first the thruster undisturbed flow field is computed, then the impingement on spacecraft surfaces is evaluated. In this paper, Plumflow, the Astrium Satellites software for undisturbed thrusters' plume computation, is presented. This software is made of several modules in order to accurately compute the flow field in the different parts of the plume. A first module computes the chemistry in the chamber, then Navier-Stokes equations are solved inside the nozzle where the flow is continuous. After that a DSMC code is used for the transitional regime near the thruster lip and finally an hybrid TPMC/source-flow method computes the free molecular far flow field. The studied case is the Astrium GmbH 10 N bipropellant thruster. Some comparisons are presented between Plumflow and Professor G.A. Bird DSMC software DS2V and with DLR experimental data. These comparisons have shown very satisfactory results. Finally, aiming at computing plume impingement, the plume flow field generated with Plumflow has been interfaced with Professor G.A. Bird 3D DSMC software DS3V. The plume impingement simulation is performed by introducing the undisturbed flow field at a boundary of DS3V computational domain. It allows us to evaluate thermal flux distribution due to Astrium 10 N thruster on a plate adjacent to the thruster and to compare with the Astrium plume impingement software.

Theroude, C.; Scremin, G.; Wartelski

2011-08-01

283

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

284

TECHNICAL BASIS FOR EVALUATING SURFACE BARRIERS TO PROTECT GROUNDWATER FROM DEEP VADOSE ZONE CONTAMINATION  

SciTech Connect

The U.S. DOE and its predecessors released nearly 2 trillion liters (450 billion gallons) of contaminated liquid into the vadose zone at the Hanford Site. Some of the contaminants currently reside in the deeper parts of the vadose zone where they are much less accessible to characterization, monitoring, and typical remediation activities. The DOE Richland Operations Office (DOE-RL) prepared a treatability test plan in 2008 to examine remediation options for addressing contaminants in the deep vadose zone; one of the technologies identified was surface barriers (also known as engineered barriers, covers, and caps). In the typical configuration, the contaminants are located relatively close to the surface, generally within 15 m, and thus they are close to the base of the surface barrier. The proximity of the surface barrier under these conditions yielded few concerns about the effectiveness of the barrier at depth, particularly for cases in which the contaminants were in a lined facility. At Hanford, however, some unlined sites have contaminants located well below depths of 15 m. The issue raised about these sites is the degree of effectiveness of a surface barrier in isolating contaminants in the deep vadose zone. Previous studies by Hanford Site and PNNL researchers suggest that surface barriers have the potential to provide a significant degree of isolation of deep vadose zone contaminants. The studies show that the actual degree of isolation is site-specific and depends on many factors, including recharge rates, barrier size, depth of contaminants, geohydrologic properties ofthe sediments, and the geochemical interactions between the contaminants and the sediments. After the DOE-RL treatability test plan was published, Pacific Northwest National Laboratory was contracted to review the information available to support surface barrier evaluation for the deep vadose zone, identify gaps in the information and outcomes necessary to fill the data gaps, and outline tasks to achieve those outcomes. Full understanding of contaminant behavior in the deep vadose zone is constrained by four key data gaps: limited access; limited data; limited time; and the lack of an accepted predictive capability for determining whether surface barriers can effectively isolate deep vadose zone contaminants. Activities designed to fill these data gaps need to have these outcomes: (1) common evaluation methodology that provides a clear, consistent, and defensible basis for evaluating groundwater impacts caused by placement of a surface barrier above deep vadose zone contamination; (2) deep vadose zone data that characterize the lithology, the spatial distribution of moisture and contaminants, the physical, chemical, and biological process that affect the mobility of each contaminant, and the impacts to the contaminants following placement of a surface barrier; (3) subsurface monitoring to provide subsurface characterization of initial conditions and changes that occur during and following remediation activities; and (4) field observations that span years to decades to validate the evaluation methodology. A set of six proposed tasks was identified to provide information needed to address the above outcomes. The proposed tasks are: (1) Evaluation Methodology - Develop common evaluation methodology that will provide a clear, consistent, and defensible basis for evaluating groundwater impacts caused by placement of a surface barrier above deep vadose zone contamination. (2) Case Studies - Conduct case studies to demonstrate the applicability ofthe common evaluation methodology and provide templates for subsequent use elsewhere. Three sites expected to have conditions that would yield valuable information and experience pertinent to deep vadose zone contamination were chosen to cover a range of conditions. The sites are BC Cribs and Trenches, U Plant Cribs, and the T Farm Interim Cover. (3) Subsurface Monitoring Technologies - Evaluate minimally invasive geophysical approaches for delineating subsurface plumes and monitoring their migration in the deep

FAYER JM; FREEDMAN VL; WARD AL; CHRONISTER GB

2010-02-24

285

Groundwater Monitoring Strategies for Variable Versus Constant Contaminant Loading Functions  

Microsoft Academic Search

Contaminant plumes were derived for constant and variable loading functions at locations within a landfill. Annually, the alternative loading functions injected the same volume of contaminated water. Mass transport modeling was used to evaluate the detection efficiencies of 25 monitoring transects, spaced evenly between the landfill and a downgradient compliance boundary. Respectively, the most efficient transects (requiring the fewest monitoring

Paul F. Hudak

1998-01-01

286

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

287

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

288

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

289

Measuring Total Dissolved Gas Pressure at a Petroleum Plume Site  

NASA Astrophysics Data System (ADS)

Groundwater contamination from petroleum hydrocarbons is ubiquitous across the country, in both urban and rural settings. Natural attenuation of petroleum contaminants may result in the production of gases (e.g. methane, carbon dioxide), in dissolved and potentially gas-phase form, which may affect the extent, persistence and remediation of petroleum hydrocarbon groundwater plumes. Current monitoring practices for gases in groundwater generally involve collecting water samples from wells or gas from gas-water separators during pumping tests, and subsequent analysis in the laboratory. Another potential option is the use of total dissolved gas pressure (TDGP) sensors, which can provide valuable real-time information on dissolved gas conditions while minimizing analytical costs. However, these have not been adequately tested or optimized for use in monitoring petroleum-contaminated groundwater. Preliminary testing of TDGP sensor measurement was performed on a selection of existing wells at a site in Ontario with previously-monitored groundwater contamination by petroleum hydrocarbons. TDGP was measured using a PT4 Tracker (Point Four Systems Inc., B.C.). Other properties such as dissolved oxygen and pH were also measured, and samples were collected and analyzed for major ions, metals, and various petroleum hydrocarbons. Results showed that 3 of the wells had contaminants, as well as elevated methane and dissolved iron. They also had lower nitrate and sulphate concentrations, but so did one uncontaminated well. The TDGP for these wells was elevated compared to background groundwater and compared to that expected for equilibration with the atmosphere. These higher values likely result from the microbial generation of dissolved methane. This data set suggests that natural biodegradation processes are occurring in the petroleum plume. However, some other wells also had elevated TDGP. They could indicate a septic plume, but the relatively low electrical conductivity (EC) is not supportive of this. It was also noted that for some wells, but not all, TDGP increased substantially following pumping, which may indicate that degassed stagnant water in the well needs to be replaced by fresher groundwater prior to TDGP measurement. These preliminary findings suggest that TDGP has the potential to provide real-time insight into where gas-producing reactions (in this case, likely methanogenesis) may be occurring in groundwater, which may be useful in assessing or monitoring natural attenuation of petroleum hydrocarbons. However, there are complicating factors that require further investigation.

Roy, J. W.; Spoelstra, J.; van Stempvoort, D.

2009-05-01

290

Transition probability/Markov chain analyses of DNAPL source zones and plumes.  

PubMed

At sites where a dense nonaqueous phase liquid (DNAPL) was spilled or released into the subsurface, estimates of the mass of DNAPL contained in the subsurface from core or monitoring well data, either in the nonaqueous or aqueous phase, can be highly uncertain because of the erratic distribution of the DNAPL due to geologic heterogeneity. In this paper, a multiphase compositional model is applied to simulate, in detail, the DNAPL saturations and aqueous-phase plume migration in a highly characterized, heterogeneous glaciofluvial aquifer, the permeability and porosity data of which were collected by researchers at the University of Tübingen, Germany. The DNAPL saturation distribution and the aqueous-phase contaminant mole fractions are then reconstructed by sampling the data from the forward simulation results using two alternate approaches, each with different degrees of sampling conditioning. To reconstruct the DNAPL source zone architecture, the aqueous-phase plume configuration, and the contaminant mass in each phase, one method employs the novel transition probability/Markov chain approach (TP/MC), while the other involves a traditional variogram analysis of the sampled data followed by ordinary kriging. The TP/MC method is typically used for facies and/or hydraulic conductivity reconstruction, but here we explore the applicability of the TP/MC method for the reconstruction of DNAPL source zones and aqueous-phase plumes. The reconstructed geometry of the DNAPL source zone, the dissolved contaminant plume, and the estimated mass in each phase are compared using the two different geostatistical modeling approaches and for various degrees of data sampling from the results of the forward simulation. It is demonstrated that the TP/MC modeling technique is robust and accurate and is a preferable alternative compared to ordinary kriging for the reconstruction of DNAPL saturation patterns and dissolved-phase contaminant plumes. PMID:17087757

Maji, R; Sudicky, E A; Panday, S; Teutsch, G

2006-01-01

291

Plumes or Not? Yes, and Plenty!  

NASA Astrophysics Data System (ADS)

We present confirmation of the detection of deep mantle plumes, earlier imaged using P waves (Montelli et al., Science 2004) using a finite-frequency inversion of long period S waves. Our data set comprises 69079 S traveltimes, 26337 SS-S and 13856 ScS-S differential traveltimes. We invert for both velocity anomalies, origin times, and the relocation of the 6834 hypocenters, using the banana-doughnut kernels derived by Dahlen et al. (GJI, 2000). The S-wave images confirm the presence of well resolved deep mantle plume beneath Ascension, Azores, Canary, Easter, Samoa and Tahiti. Among the deep plumes that were not very well resolved in the earlier P-wave study, the S wave inversion shows a robust extension all the way to the CMB of the plumes beneath Cape Verde, Cook Island and Kerguelen. The presence of plumes rising from the base of the mantle but not reaching yet the surface in the Coral Sea, East of Solomon and South of Java is validated. Plumes such as Bowie, Eifel, Etna and Seychelles remain mostly confined to the upper mantle. However, the new S-wave images reopen the question on the depth extent of Iceland and Galapagos plumes. The weakening of the plume in the mid-mantle beneath Iceland is confirmed, but the S inversion clearly shows the presence of a low velocity zone at greater depth that was not visible in the P-wave images. For Galapagos, the new S-wave images show more clearly a possible connection of the plume with a broad low velocity anomaly in the lowermost mantle that feeds Easter as well. We will present the final S-wave plume images and will provide a synthesis of our findings in the light of existing ideas about plume characteristics and their superficial signature.

Montelli, R.; Nolet, G.; Dahlen, F.; Masters, G.

2004-12-01

292

Probabilistic Risk Analysis and Fault Trees as Tools in Improving the Delineation of Wellhead Protection Areas: An Initial Discussion  

Microsoft Academic Search

Delineation of a wellhead protection area (WHPA) is a critical component of managing \\/ protecting the aquifer(s) supplying potable water to a public water-supply well. While a number of previous authors have addressed questions related to uncertainties in advective capture zones, methods for assessing WHPAs in the presence of uncertainty in the chemistry of groundwater contaminants, the relationship between land-use

C. M. Rodak; S. E. Silliman

2010-01-01

293

New indices for the spatial validation of plume forecasts with observations of smoke plumes from grassfires  

NASA Astrophysics Data System (ADS)

The purpose of this work is to propose new indices for the spatial validation of hazardous plumes forecast, and apply and test them with data of a case study. One, the Plume-Overlap-Area Hit index, is a modification of a widely used index that considers the overlap area between observed and forecast plumes. The other one, the Plume-Mean-Orientation Hit index, introduces a new concept in plume forecast validation, i.e., the mean direction of plume propagation. These two indices are combined in a new two-dimensional Combined-Direction-Area Hit index. The new indices are applied to the spatial validation of smoke plume forecast for a case study of uncontrolled grassfires that took place during April and May 2008 in the La Plata River region in South America. Operational models at the Argentine National Meteorological Service (SMN) are employed to produce the plume forecast. The HIRHYLTAD dispersion model is used to forecast the smoke plumes, employing the Eta/SMN meteorological forecast model outputs. The forecast plumes are compared to the observed plumes in high-resolution MODIS imagery from AQUA and TERRA satellites, from which a total of 59 smoke plumes are identified. The study concludes that the presented methodology that employs operational meteorological models and simplified dispersion models can be used to produce reasonably accurate forecasts of the areas affected by the smoke plumes that originate in forest and grassland fires, particularly in cases when limited information is available about the fires. Although the present study is specifically applied to smoke plumes, the validation technique with the proposed indices can be of utility to study pollutant plumes of diverse nature.

Blanco, Joaquín E.; Berri, Guillermo J.

2013-03-01

294

Automatic delineation of geomorphological slope units  

NASA Astrophysics Data System (ADS)

Slope units are portions of land surface, defined by the general requirement of maximizing homogeneity within a single unit and heterogeneity between different units, but whose formal characterization and practical delineation has been done in different ways. This is often justified by the statement that the slope unit partitioning of a territory can be used to describe a variety of landforms and processes, and for the assessment of natural hazards. As a result, they need to be tailored according to the specific model in use. This may result in an ambiguous definition of such objects, while an objective definition is highly desirable, which would also allow their reproducibility. We have developed a publicly accessible Web Processing Service (WPS) with the aim of incrementally achieve a satisfactory definition of slope unit. The service allows any user to connect to a CNR-IRPI (Perugia) server, upload his own Digital Elevation Model (DEM) and optional additional data, specify parameters constraining the size and aspect of slope units, and quickly obtain the result in a layer in vector format. The calculation is performed using a parallel algorithm, resulting in a processing time short enough to allow the user to tune the input parameters, repeating the process for a sufficient number of times in order to obtain a satisfactory result. We use quantitative criteria to define and draw the slope units, depending on the input parameters. The algorithm starts from a hydrologically consistent partition of the study area into half-basins with a large number of contributing DEM cells. Each of the half-basins is then checked against a few requirements: maximum area required by the user and maximum standard deviation of the aspect on two orthogonal directions. Those specific half-basin that do not meet the requirements are partitioned further, requiring a lower number of contributing cells. The process is iterated until no half-basin exceeds the user-specified thresholds. Our aim is to encourage users to test the algorithm on a large number of areas with different topographies so that new, meaningful requirements on the individual half-basins can be defined and included in our process, in order to achieve a robust and reproducible algorithm embodying a vast class of desiderata in the slope unit definition. This will eventually constitute a performing and customizable tool for the investigation of a variety of geomorphological phenomena.

Alvioli, Massimiliano; Marchesini, Ivan; Fiorucci, Federica; Ardizzone, Francesca; Rossi, Mauro; Reichenbach, Paola; Guzzetti, Fausto

2014-05-01

295

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

296

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...

297

VISUAL PLUMES MIXING ZONE MODELING SOFTWARE  

EPA Science Inventory

The U.S. Environmental Protection Agency has a long history of both supporting plume model development and providing mixing zone modeling software. The Visual Plumes model is the most recent addition to the suite of public-domain models available through the EPA-Athens Center f...

298

Io with Loki Plume on Bright Limb  

NASA Technical Reports Server (NTRS)

Voyager 1 image of Io showing active plume of Loki on limb. Heart-shaped feature southeast of Loki consists of fallout deposits from active plume Pele. The images that make up this mosaic were taken from an average distance of approximately 490,000 kilometers (340,000 miles).

1990-01-01

299

Numerical Simulations of Europa Hydrothermal Plumes  

NASA Astrophysics Data System (ADS)

The liquid water interiors of Europa and other icy moons of the outer solar system are likely to be driven by geothermal heating from the sea floor, leading to the development of buoyant hydrothermal plumes. These plumes potentially control icy surface geomorphology, and are of interest to astrobiologists. We have performed a series of simulations of these plumes using the MITGCM. We assume in this experiment that Europa's ocean is deep (of order 100 km) and unstratified, and that plume buoyancy is controlled by temperature, not composition. A series of experiments was performed to explore a limited region of parameter space, with ocean depth H ranging from 50 to 100 km deep, source heat flux Q between 1 and 10 GW, and values of the Coriolis parameter f between 30% and 90% of the Europa average value. As predicted by earlier work, the plumes in our simulations form narrow cylindrical chimneys (a few km across) under the influence of the Coriolis effect. These plumes broaden over time until they become baroclinically unstable, breaking up into cone-shaped eddies when they become 20-35 km in diameter; the shed eddies are of a similar size. Large-scale currents in the region of the plume range between 1.5 and 5 cm/s; temperature anomalies in the plume far from the seafloor are tiny, varying between 30 and 160 microkelvin. Variations in plume size, shape, speed, and temperature are in excellent agreement with previous laboratory tank experiments, and in rough agreement with theoretical predictions. Plume dynamics and geometry are controlled by a "natural Rossby number" which depends strongly on depth H and Coriolis parameter f, but only weakly on source heat flux Q. However, some specific theoretical predictions are not borne out by these simulations. The time elapsed between startup of the source and the beginning of eddy-shedding is much less variable than predicted; also, the plume temperature varies with ocean depth H when our theory says it should not. Both of these results can be explained by noting that the theory assumes that mixing between plume fluid and ambient fluid occurs only very near the heat source, but this does not appear to be true in the simulations. 3-d view of simulated Europa plume. Boundary indicated by 3-d surface; flat surfaces at left and top show temperature in sections through the plume.

Goodman, J. C.; Lenferink, E.

2009-12-01

300

MODELING PLUMES IN SMALL STREAMS  

EPA Science Inventory

Pesticides accumulate on land surfaces from agricultural, commercial, and domestic application, and wash into streams and rivers during dry and wet weather. Flood water retention basins or structures often collect this contaminated runoff, providing intermediate storage and limit...

301

Water Vapor Enhancement in Prescribed Fire Plumes  

NASA Astrophysics Data System (ADS)

In situ radiosonde measurements were obtained during multiple prescribed fires at the Joseph W. Jones Ecological Research Center at Ichauway, Georgia in March and July of 2008. Data were obtained from prescribed fires conducted in longleaf pine ecosystems. After significant smoke generation was observed, radiosondes were launched downwind of the fire front and rose directly into the smoke plumes. Radiosondes were also launched before each burn to obtain ambient background conditions. This provided a unique dataset of smoke plume moisture to determine how moisture enhancement from fire smoke alters the dynamics of the smoke plume. Preliminary analysis of results show moisture enhancement occurred in all smoke plumes with relative humidity values increasing by 10 to 30 percent and water vapor mixing ratios increasing by 1 to 4 g kg-1. Understanding the moisture enhancement in prescribed fire smoke plumes will help determine the convective dynamics that occur in major wildland fires and convection columns.

Kiefer, C. M.; Clements, C. B.; Potter, B. E.; Strenfel, S. J.

2008-12-01

302

Plume detachment from a magnetic nozzle  

SciTech Connect

High-powered electric propulsion thrusters utilizing a magnetized plasma require that plasma exhaust detach from the applied magnetic field in order to produce thrust. This paper presents experimental results demonstrating that a sufficiently energetic and flowing plasma can indeed detach from a magnetic nozzle. Microwave interferometer and probe measurements provide plume density, electron temperature, and ion flux measurements in the nozzle region. Measurements of ion flux show a low-beta plasma plume which follows applied magnetic field lines until the plasma kinetic pressure reaches the magnetic pressure and a high-beta plume expanding ballistically afterward. Several magnetic configurations were tested including a reversed field nozzle configuration. Despite the dramatic change in magnetic field profile, the reversed field configuration yielded little measurable change in plume trajectory, demonstrating the plume is detached. Numerical simulations yield density profiles in agreement with the experimental results.

Deline, Christopher A. [University of Michigan, Ann Arbor, Michigan 48109 (United States); Bengtson, Roger D.; Breizman, Boris N.; Tushentsov, Mikhail R. [Institute for Fusion Studies, University of Texas at Austin, Austin, Texas 78712 (United States); Jones, Jonathan E.; Chavers, D. Greg; Dobson, Chris C. [Marshall Space Flight Center, Huntsville, Alabama 35805 (United States); Schuettpelz, Branwen M. [University of Alabama at Huntsville, Huntsville, Alabama 35899 (United States)

2009-03-15

303

Natural biodegradation of organic contaminants in groundwater  

SciTech Connect

There has recently been a growing awareness that natural processes are degrading contaminants of concern, and that the contribution these natural processes make to achieving cleanup goals needs to be formally considered during site-specific cleanup. Historical case data from a large number of releases has been used to evaluate the expectation for natural attenuation to contribute to the cleanup of petroleum hydrocarbons and chlorinated solvents. The use of historical case data has several advantages, among them: 1) sites can reduce characterization costs by sharing information on key hydrogeologic parameters controlling contaminant fate and transport, and 2) standard reference frameworks can be developed that individual sites can use as a basis of comparison regarding plume behavior. Definition of cleanup times must take into account basic constraints imposed by natural laws governing the transport and natural degradation process of petroleum hydrocarbons. The actual time to reach groundwater cleanup goals is determined by these laws and the limitations on residual subsurface contamination attenuation rates, through either active or natural biological processes. These limitations will practically constrain the time to achieve low concentration cleanup goals. Recognition is needed that sites will need to be transitioned to remediation by natural processes at some point following implementation of active remediation options. The results of an analysis of approximately 1800 California and 600 Texas fuel hydrocarbon (FHC) releases and 2.50 chlorinated volatile organic compound (CVOC) plumes will be summarized. Plume lengths and natural biodegradation potential were evaluated. For FHC releases, 90% of benzene groundwater plumes were less than 280 feet in length and evidence of natural biodegradation was found to be present at all sites studied in detail. For CVOC releases, source strength and groundwater flow velocity are dominant factors controlling groundwater plume lengths. After adjusting for these factors, biodegradation also appears to limit the length of CVOC plumes in many instances. The application of natural biodegradation processes as a remediation approach will depend on the time frame for anticipated beneficial use of the affected groundwater.

McNab, W W; Rice, D W

1998-09-23

304

MISR Observations of Etna Volcanic Plumes  

NASA Technical Reports Server (NTRS)

In the last twelve years, Mt. Etna, located in eastern Sicily, has produced a great number of explosive eruptions. Volcanic plumes have risen to several km above sea level and created problems for aviation and the communities living near the volcano. A reduction of hazards may be accomplished using remote sensing techniques to evaluate important features of volcanic plumes. Since 2000, the Multiangle Imaging SpectroRadiometer (MISR) on board NASA s Terra spacecraft has been extensively used to study aerosol dispersal and to extract the three-dimensional structure of plumes coming from anthropogenic or natural sources, including volcanoes. In the present work, MISR data from several explosive events occurring at Etna are analyzed using a program named MINX (MISR INteractive eXplorer). MINX uses stereo matching techniques to evaluate the height of the volcanic aerosol with a precision of a few hundred meters, and extracts aerosol properties from the MISR Standard products. We analyzed twenty volcanic plumes produced during the 2000, 2001, 2002-03, 2006 and 2008 Etna eruptions, finding that volcanic aerosol dispersal and column height obtained by this analysis is in good agreement with ground-based observations. MISR aerosol type retrievals: (1) clearly distinguish volcanic plumes that are sulphate and/or water vapor dominated from ash-dominated ones; (2) detect even low concentrations of volcanic ash in the atmosphere; (3) demonstrate that sulphate and/or water vapor dominated plumes consist of smaller-sized particles compared to ash plumes. This work highlights the potential of MISR to detect important volcanic plume characteristics that can be used to constrain the eruption source parameters in volcanic ash dispersion models. Further, the possibility of discriminating sulphate and/or water vapor dominated plumes from ash-dominated ones is important to better understand the atmospheric impact of these plumes.

Scollo, S.; Kahn, R. A.; Nelson, D. L.; Coltelli, M.; Diner, D. J.; Garay, M. J.; Realmuto, V. J.

2012-01-01

305

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

306

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

307

Ground water contaminant source and transport parameter identification by correlation coefficient optimization  

Microsoft Academic Search

The initial step in a ground water contamination remediation process is to identify the extent of the plume. One way to optimize well deployment is to solve an inverse contaminant transport problem. Inverse procedures bas4ed on correlation coefficient optimization are developed to locate ground water contaminant sources and to identify transport parameters. For cases involving two-dimensional instantaneous and continuous sources,

P. Sidauruk; A. H. D. Cheng; D. Ouazar

1998-01-01

308

Snohomish Estuary Wetlands Study. Volume IV. Delineation of Wetland Boundaries.  

National Technical Information Service (NTIS)

Wetlands boundaries in the Snohomish River Basin were delineated according to Army Corps of Engineers (Corps) definition presented in Corps permit regulations (33 CFR 323.2). These definitions are based primarily on occurrence of wetland vegetation and co...

M. E. Boule G. B. Shea

1978-01-01

309

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

310

356. Delineator Unknown March 1946 STATE OF CALIFORNIA; DEPARTMENT OF ...  

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

356. Delineator Unknown March 1946 STATE OF CALIFORNIA; DEPARTMENT OF PUBLIC WORKS; SAN FRANCISCO - OAKLAND BAY BRIDGE; GENERAL DATA; PLAT III - San Francisco Oakland Bay Bridge, Spanning San Francisco Bay, San Francisco, San Francisco County, CA

311

Role Delineation Refinement and Verification - the Comprehensive Report.  

National Technical Information Service (NTIS)

This report contains the results of the exploratory research conducted by the American Physical Therapy Association. This research involved physical therapist and physical therapist assistant role delineation refinement and verification, entry-level role ...

G. L. Garrett

1980-01-01

312

1. Photocopy of delineation, American Architect and Building News, Vol ...  

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

1. Photocopy of delineation, American Architect and Building News, Vol VI, No. 146, (September 27, 1879). SHOWING FRONT ELEVATION AND FLOOR PLAN - G. B. P. Carpenter House, 100 Block of Polk Streets (Prospect Point), Burlington, Des Moines County, IA

313

1. Photocopy of architectural measured drawing Delineator unknown, ca. 1982 ...  

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

1. Photocopy of architectural measured drawing Delineator unknown, ca. 1982 SITE PLAN SHOWING HISTORIC DISTRICT AND LOCATION OF NEW ADDITION - U. S. Veterans Administration Medical Center, 2100 Ridgecrest Southeast, Albuquerque, Bernalillo County, NM

314

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

315

Evaluation of Durable Lane Delineation Materials. Interim Report May 1986.  

National Technical Information Service (NTIS)

The objective of the study was to evaluate the cost-effectiveness of marking materials by means of field tests and to make recommendations concerning the optimum lane delineation materials. Materials tested include 100-percent solid epoxy paint, polyester...

K. R. Agent J. G. Pigman

1986-01-01

316

Site Characterization To Support Use Of Monitored Natural Attentuation For Remediation Of Inorganic Contaminants In Groundwater  

EPA Science Inventory

Technical recommendations have recently been published by the U.S. Environmental Protection Agency to address site characterization needed to support selection of Monitored Natural Attenuation (MNA) for cleanup of inorganic contaminant plumes in groundwater. Immobilization onto ...

317

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

318

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

319

Automated tumor delineation using joint PET/CT information  

NASA Astrophysics Data System (ADS)

In this paper, we propose a new method for automated delineation of tumor boundaries in whole-body PET/CT by jointly using information from both PET and diagnostic CT images. Our method takes advantage of initial robust hot spot detection and segmentation performed in PET to provide a conservative tumor structure delineation. Using this estimate as initialization, a model for tumor appearance and shape in corresponding CT structures is learned and the model provides the basis for classifying each voxel to either lesion or background class. This CT classification is then probabilistically integrated with PET classification using the joint likelihood ratio test technique to derive the final delineation. More accurate and reproducible tumor delineation is achieved as a result of such multi-modal tumor delineation, without additional user intervention. The method is particular useful to improve the PET delineation result when there are clear contrast edges in CT between tumor and healthy tissue, and to enable CT segmentation guided by PET when such contrast difference is absent in CT.

Potesil, Vaclav; Huang, Xiaolei; Zhou, Xiang Sean

2007-03-01

320

A new method for verification of delineated channel networks  

NASA Astrophysics Data System (ADS)

methods are used to delineate channel networks. The most widely used are the contributing area method, area-slope method, and grid network ordering method. The number of delineated channels depends on the threshold adopted when using each method. However, the appropriate threshold value required to delineate channel networks, and their corresponding accuracies, are still uncertain. The consistency between the delineated channels and actual channels can be evaluated by carrying out extensive field surveys, but these require significant time and cost. Accurate knowledge of delineated channel networks is vital, and is achievable more efficiently and simply. A new method of calculating the accuracy of delineated channel networks is introduced in this study. Channel cross-section profiles throughout the channel network were examined and three new incision indices were derived: an incised channel index, a partially incised channel index, and a nonincised channel index. The indices were found useful for setting appropriate threshold values for actual channel networks. Three small catchments in Wellington, New South Wales (NSW), Australia, were investigated in this study.

Liu, Zhe; Khan, Urooj; Sharma, Ashish

2014-03-01

321

Deep mantle plume osmium isotope signature from West Greenland Tertiary picrites  

NASA Astrophysics Data System (ADS)

Picrites from Nuussuaq Peninsula and Qeqertarssuaq (Disko) Island, West Greenland, preserve trace element and isotopic signatures reflecting the composition of the Icelandic plume head. Os isotope ratios are low ( 187Os/ 188Os (i)=0.1272-0.1371) in terms of global plume related magmatism, and this is coupled with anomalously high Os abundances and radiogenic 143Nd/ 144Nd (i) isotopes. Crustally contaminated basalts within the West Greenland sequences possess Os and Nd isotopic signatures consistent with mixing between initial plume head compositions and two discrete types of West Greenland continental crust. One crustal component is of a local sedimentary origin, and the other is typical of ancient felsic crust. The low Os isotopic signatures of the picritic units are considered to be those of the initial mantle plume. The fact that such low Os isotope ratios occur in sequences with high 3He/ 4He, and the non-systematic variation in Os isotopes with indices of fractionation/accumulation and Pb isotopes, argue against mixing with depleted MORB mantle or ancient subcontinental lithospheric mantle. The high Os concentrations in the picrites are attributed to high degrees of partial melting (>25%) of mantle containing no residual sulphide. This is consistent with models for plume heads in which anomalous mantle temperatures initiate melting at high pressures generating large degrees of partial melting. Unradiogenic Os and radiogenic Nd components in plume-related CFB magmatism may preserve contributions from a reservoir which is sampled only occasionally in young oceanic basalts. Such a reservoir shares Os isotopic features with the primitive upper mantle (PUM), which may also be manifest in the 'Kea' component of Hawaiian magmatism. Therefore, portions of the West Greenland continental flood basalt province arguably represent the first direct sampling of unmodified plume head material derived from the lower mantle or lower portions of the upper mantle.

Schaefer, Bruce F.; Parkinson, Ian J.; Hawkesworth, Chris J.

2000-01-01

322

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

323

Tritium plume dynamics in the shallow unsaturated zone in an arid environment  

USGS Publications Warehouse

The spatiotemporal variability of a tritium plume in the shallow unsaturated zone and the mechanisms controlling its transport were evaluated during a 10-yr study. Plume movement was minimal and its mass declined by 68%. Upward-directed diffusive-vapor tritium fluxes and radioactive decay accounted for most of the observed plume-mass declines. Effective isolation of tritium (3H) and other contaminants at waste-burial facilities requires improved understanding of transport processes and pathways. Previous studies documented an anomalously widespread (i.e., theoretically unexpected) distribution of 3H (>400 m from burial trenches) in a dry, sub-root-zone gravelly layer (1–2-m depth) adjacent to a low-level radioactive waste (LLRW) burial facility in the Amargosa Desert, Nevada, that closed in 1992. The objectives of this study were to: (i) characterize long-term, spatiotemporal variability of 3H plumes; and (ii) quantify the processes controlling 3H behavior in the sub-root-zone gravelly layer beneath native vegetation adjacent to the facility. Geostatistical methods, spatial moment analyses, and mass flux calculations were applied to a spatiotemporally comprehensive, 10-yr data set (2001–2011). Results showed minimal bulk-plume advancement during the study period and limited Fickian spreading of mass. Observed spreading rates were generally consistent with theoretical vapor-phase dispersion. The plume mass diminished more rapidly than would be expected from radioactive decay alone, indicating net efflux from the plume. Estimates of upward 3H efflux via diffusive-vapor movement were >10× greater than by dispersive-vapor or total-liquid movement. Total vertical fluxes were >20× greater than lateral diffusive-vapor fluxes, highlighting the importance of upward migration toward the land surface. Mass-balance calculations showed that radioactive decay and upward diffusive-vapor fluxes contributed the majority of plume loss. Results indicate that plume losses substantially exceeded any continuing 3H contribution to the plume from the LLRW facility during 2001 to 2011 and suggest that the widespread 3H distribution resulted from transport before 2001.

Maples, S. R.; Andraski, B. J.; Stonestrom, D. A.; Cooper, C. A.; Pohll, G.; Michel, R. L.

2014-01-01

324

Back contamination.  

NASA Technical Reports Server (NTRS)

Discussion of the concept and implications of back contamination and of the ways and means for its prevention. Back contamination is defined as contamination of the terrestrial biosphere with organisms or materials returned from outer space that are capable of potentially harmful terrestrial activity. Since the question of whether or not life exists on other planets may, in reality, not be answered until many samples are returned to earth for detailed study, requirements for the prevention of back contamination are necessary. A review of methods of microbiologic contamination control is followed by a discussion of the nature of back contamination and its risk levels, contamination sources and locations, and possible defenses against back contamination. The U.S. lunar back contamination program is described and shown to provide a valuable basis for further refining the technology for the control of planetary back contamination.

Phillips, G. B.

1971-01-01

325

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

326

Occurrence and attenuation of specific organic compounds in the groundwater plume at a former gasworks site  

NASA Astrophysics Data System (ADS)

The changing contaminant pattern with travelled distance was investigated in the anaerobic groundwater plume downstream from an extended zone containing residual NAPL at a former gas manufacturing plant. With increasing distance, O- and N-heterocyclic aromatic compounds are enriched in the plume relative to the usually assessed coal tar constituents (poly- and monocyclic aromatic compounds). In a first approximation, the overall concentration decrease of the investigated compounds follows a first order overall decay. The half life distance in the plume downgradient from the source varied between 20 m for benzene and up to 167-303 m for alkyl-naphthalenes. Acenaphthene is degraded only within about 50 m downstream from the source area, then its concentration remains constant (ca. 180 ?g/l) and far above the legal limit. Dimethyl-benzofurans were the most recalcitrant among all compounds which could be quantified with the analytical method available. The overall groundwater contamination in the plume is seriously underestimated if only BTEX and 16-EPA-PAHs are monitored.

Zamfirescu, Daniela; Grathwohl, Peter

2001-12-01

327

Evolution of REDOX Tank Waste Plumes in Hanford Vadose Zone: A Conceptual Model Developed Through Reactive Transport Studies  

SciTech Connect

Decisions on remedial actions for leakage of highly radioactive tank waste solutions at the Hanford Site will depend highly on understanding of the current distribution and future migration of contaminants in the subsurface. The geochemical data obtained from borehole drilling at SX tank farm in the 200 Area, by Tank Farm Vadose Zone Characterization Project of the U.S. Department of Energy, revealed valuable insights as well as some results that challenge our basic understanding of waste plume evolution. In response to these needs and challenges, we have been investigating reactive transport of tank waste solutions in Hanford sediments through laboratory column experiments combined with geochemical modeling. Analyses of solid and aqueous phases within different zones of contaminant plumes, along with thermodynamic predictions provide the basis for our conceptual model. This model reveals the primary processes controlling evolution of REDOX waste plumes in the Hanford vadose zone.

Wan, Jiamin; Tokunaga, Tetsu K.; Larsen, Joern T.; Zheng, Zuoping

2003-03-27

328

Grand Comore Island: A well-constrained “low 3He/4He” mantle plume  

NASA Astrophysics Data System (ADS)

We report He isotope ( 3He/ 4He) variations in samples from alkali basaltic and basanitic lava flows from Grande Comore Island complemented by existing [1,2] [C. Class, S.L. Goldstein, Plume-lithosphere interactions in the ocean basins: constraints from the source mineralogy. Earth Planet. Sci. Lett., 150 (1997) 245-260, C. Class, S.L. Goldstein, R. Altherr, P. Bachèchlery, The process of plume-lithosphere interaction in the ocean basins—the case of Grande Comore. J. Petrol., 39 (5) (1998) 881-903] and new Sr-Nd-Pb isotope ratios and major and trace element abundances. He isotope data in samples from Tristan da Cunha and Gough islands and the Huri Hills in Kenya are reported also. Grande Comore 3He/ 4He ratios vary between 5.05 and 7.08 RA ( 4He/ 3He ? 141,000-101,000). Chemical and Sr-Nd-Pb isotopic variations of Grande Comore lavas were previously shown to reflect melts derived from the deep mantle plume and the shallow lithospheric mantle [1-3] [C. Class, S.L. Goldstein, Plume-lithosphere interactions in the ocean basins: constraints from the source mineralogy. Earth Planet. Sci. Lett., 150 (1997) 245-260, C. Class, S.L. Goldstein, R. Altherr, P. Bachèchlery, The process of plume-lithosphere interaction in the ocean basins-the case of Grande Comore. J. Petrol., 39 (5) (1998) 881-903, C. Claude-Ivanaj, B. Bourdon, C.J. Allègre, Ra-Th-Sr isotope systematics in Grande Comore Island: a case study of plume-lithosphere interaction. Earth Planet. Sci. Lett. 164 (1998) 99-117]. The lithosphere-dominated end-member (La Grille volcano) shows uniform 3He/ 4He ratios within error of 6.75-7.08 RA ( 4He/ 3He ? 106,000-101,000) over a range of [He] = 36-428 × 10 - 9 ccSTP/g. The plume end-member (of the Karthala volcano suite), as constrained by Sr, Nd, Pb isotope ratios, shows uniformly lower 3He/ 4He ratios with 5.05-5.41 RA ( 4He/ 3He ? 141,000-132,000) over a range of [He] = 11-136 × 10 - 9 ccSTP/g. All samples show good correlations between Sr-Nd-He isotope ratios, indicating that the Grande Comore 3He/ 4He ratios are not significantly influenced by crustal contamination and reflect recent mixing between plume- and lithosphere-derived melts. The lithosphere beneath Grande Comore has retained its MORB-like helium isotopic composition, which suggests that the previously identified amphibole-forming metasomatism of the lithospheric mantle [1] [C. Class, S.L. Goldstein, Plume-lithosphere interactions in the ocean basins: constraints from the source mineralogy. Earth Planet. Sci. Lett., 150 (1997) 245-260] occurred prior to the arrival of the Comoro plume. The well-constrained 3He/ 4He = 5.2 ± 0.2 RA ( 4He/ 3He ? 137,000 ± 5000) of the Comoro plume confirms the existence of "low 3He/ 4He" mantle plumes. A global compilation of OIB shows that OIB from "low 3He/ 4He" plumes form one "side" of the roughly triangular distribution of the global OIB data set in 143Nd/ 144Nd versus 206Pb/ 204Pb and 208Pb/ 204Pb, encompassing the lowest Nd to the highest Pb isotope ratios. It is also shown that "low 3He/ 4He" plumes are more enriched in Th and U relative to other plumes.

Class, Cornelia; Goldstein, Steven L.; Stute, Martin; Kurz, Mark D.; Schlosser, Peter

2005-05-01

329

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

330

Assessing impacts of partial mass depletion in DNAPL source zones: II. Coupling source strength functions to plume evolution  

Microsoft Academic Search

Analytical solutions, describing the time-dependent DNAPL source-zone mass and contaminant discharge rate, derived previously in Part I [Falta, R.W., Rao, P.S., Basu, N., this issue. Assessing the impacts of partial mass depletion in DNAPL source zones: I. Analytical modeling of source strength functions and plume response. J. Contam. Hydrol.] are used as a flux-boundary condition in a semi-analytical contaminant transport

Ronald W. Falta; Nandita Basu; P. Suresh Rao

2005-01-01

331

Subsurface Contaminants Focus Area annual report 1997  

SciTech Connect

In support of its vision for technological excellence, the Subsurface Contaminants Focus Area (SCFA) has identified three strategic goals. The three goals of the SCFA are: Contain and/or stabilize contamination sources that pose an imminent threat to surface and ground waters; Delineate DNAPL contamination in the subsurface and remediate DNAPL-contaminated soils and ground water; and Remove a full range of metal and radionuclide contamination in soils and ground water. To meet the challenges of remediating subsurface contaminants in soils and ground water, SCFA funded more than 40 technologies in fiscal year 1997. These technologies are grouped according to the following product lines: Dense Nonaqueous-Phase Liquids; Metals and Radionuclides; Source Term Containment; and Source Term Remediation. This report briefly describes the SCFA 1997 technologies and showcases a few key technologies in each product line.

NONE

1997-12-31

332

Winds and the orientation of a coastal plane estuary plume  

Microsoft Academic Search

Based on a calibrated coastal plane estuary plume model, ideal model hindcasts of estuary plumes are used to describe the evolution of the plume pattern in response to river discharge and local wind forcing by selecting a typical partially mixed estuary (the Cape Fear River Estuary or CFRE). With the help of an existing calibrated plume model, as described by

Meng Xia; Lian Xie; Leonard J. Pietrafesa

2010-01-01

333

Assessment of analytical techniques for predicting solid propellant exhaust plumes and plume impingement environments  

NASA Technical Reports Server (NTRS)

An analysis of experimental nozzle, exhaust plume, and exhaust plume impingement data is presented. The data were obtained for subscale solid propellant motors with propellant Al loadings of 2, 10 and 15% exhausting to simulated altitudes of 50,000, 100,000 and 112,000 ft. Analytical predictions were made using a fully coupled two-phase method of characteristics numerical solution and a technique for defining thermal and pressure environments experienced by bodies immersed in two-phase exhaust plumes.

Tevepaugh, J. A.; Smith, S. D.; Penny, M. M.

1977-01-01

334

Numerical investigation for the interaction between the Afar plume, the Kenya plume and the Tanzania craton  

NASA Astrophysics Data System (ADS)

Geochemical evidence suggests that the Tertiary basalts along the East African Rift were created by two series of volcanic eruptions from separated mantle sources. The basalts in Tanzania, Kenya, and southern Ethiopia were attributed to the Kenya mantle plume initiated 45 Myr ago, while the Ethiopia-Yemen basalts were products of the younger (31 Ma) Afar plume. We carry out numerical modeling to investigate how this double plume system, the Tanzania craton, and the African plate motion interplay to result in the spatial-time pattern of magmatism observed. The African plate motion and the Tanzania craton were implemented as known physical parameters. The models were then tuned on the locations and strengths of the plumes and the range of rheology of the upper mantle against two critical observations: the coexistence of basalts derived directly or indirectly from the two plumes in southern Ethiopia, and buoyancy flux estimation of the Afar plume. The confrontation between plumes will generate an approximately stationary stagnant streamline between the plumes. Therefore, the plume head material will not mix or underplate each other, making the isolation of the mantle sources for melting. With the plausible physical parameters, our preferred model can generate a good match for the spatial and temporal magma distribution in Ethiopia and Yemen. The south-coming Tanzania craton and the expanding flow front of the Afar plume together deflect the Kenya plume material to the sense of asymmetry. However, it is insufficient to explain the observation in which the abundant magmatism along the eastern branch vs. little on the western branch of the rift. The plume has been eroding the cratonic root since 20 Ma.

Lin, S.; Kuo, B.; Chiao, L.

2004-05-01

335

Groundwater contamination by nitrates and chlorides washed out from phosphorite ores in the Negev Desert, Israel  

NASA Astrophysics Data System (ADS)

A sharp rise in the nitrate-content (up to 7200 mg L -1) and in the chlorinity (up to 92000 mg L -1) was observed during the 1980's in the water of the Aqrabim spring outflowing in the Negev desert, Israel. The source of pollutants was traced to a resevoir of wastewater derived from the dressing of phosphorite ores mined in the area. These ores and the overlying gravels are characterized by high concentrations of soluble nitrates, chlorides and sulphates. Groundwater flow-paths were delineated by using chemical changes observed in the wastewater reservoir. During the last 6 years, the continuous percolation of wastewater enhanced the flushing of chalk and clay particles from the fractured chert aquifer causing a sharp increase in groundwater flow-rates from the reservoir to the springs from 7.5 m day -1 (in 1980) to 53 m day -1 (in 1986). This change suggests the development of new flow paths. The resulting rapid propagation of the contamination plume may have disastrous consequences on the limited water resources in the northern Arava-Dead Sea area.

Rosenthal, E.; Magaritz, M.; Ronen, D.; Gilead, D.

1988-09-01

336

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

337

Mathematical Modeling of Cooling-Tower Plumes.  

National Technical Information Service (NTIS)

The vast majority of mathematical models used to predict plume rise from natural-draft (NDCT) and mechanical-draft (MDCT) cooling towers employ the integral approach. The following significant areas of controversy exist in the theoretical development of s...

R. Carhart A. Policastro

1982-01-01

338

Chemical Plume Tracing: Insects as Model Navigators.  

National Technical Information Service (NTIS)

Control of robotic vehicles maneuvering upwind along an odor plume, generated by pollutant sources or unexploded ordnance, so that they discover the odor's source is an unsolved problem. Our goals have been (1) to understand how flying insects reliably lo...

R. T. Carde J. A. Farrell

2002-01-01

339

Propagation of an atmospheric pressure plasma plume  

SciTech Connect

The ''plasma bullet'' behavior of atmospheric pressure plasma plumes has recently attracted significant interest. In this paper, a specially designed plasma jet device is used to study this phenomenon. It is found that a helium primary plasma can propagate through the wall of a dielectric tube and keep propagating inside the dielectric tube (secondary plasma). High-speed photographs show that the primary plasma disappears before the secondary plasma starts to propagate. Both plumes propagate at a hypersonic speed. Detailed studies on the dynamics of the plasma plumes show that the local electric field induced by the charges on the surface of the dielectric tube plays an important role in the ignition of the secondary plasma. This indicates that the propagation of the plasma plumes may be attributed to the local electric field induced by the charges in the bulletlike plasma volume.

Lu, X.; Xiong, Q.; Xiong, Z.; Hu, J.; Zhou, F.; Gong, W.; Xian, Y.; Zou, C.; Tang, Z.; Jiang, Z.; Pan, Y. [College of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China)

2009-02-15

340

Rocket Plume Tomography of Combustion Species.  

National Technical Information Service (NTIS)

Interest in accurate detection and targeting of aggressor missiles has received considerable interest with the national priority of developing a missile defense system. Understanding the thermal signatures of the exhaust plumes of such missiles is key to ...

J. M. Kutrieb

2001-01-01

341

Ultraviolet Emission from Rocket Motor Plumes.  

National Technical Information Service (NTIS)

Atmospheric limitations on the spectral region of the ultraviolet appropriate for detection of emissions from rocket motor plumes are considered. Origins of ultraviolet emission as spectral continua, bands and lines from the rocket motor exhaust flow and ...

D. Kilpin

1994-01-01

342

Revealing the Neutral Composition of Enceladus’ Plume  

NASA Astrophysics Data System (ADS)

Saturn’s moon Enceladus ejects a substantial plume of icy material from surface fractures near its south pole. The Cassini spacecraft’s Ion and Neutral Mass Spectrometer (INMS) has been instrumental in determining the neutral composition of Enceladus’ plume, which is dominated by H2O, CO2, CH4, and includes a host of complex organic species. INMS observations in 2008 provided the positive identification of NH3 and the likely presence of 40Ar, hinting at the presence of liquid water reservoirs below the moon’s ice shell. Encounters with Enceladus in the fall of 2009 have brought the Cassini spacecraft substantially closer to the plume sources than previous flybys, with trajectories optimized for measurements of neutral composition. Results from the latest Cassini-INMS data sets are presented here to highlight and further understand the complex neutral composition of Enceladus’ plume.

Magee, B.; Waite, J. H.

2009-12-01

343

Radar scattering behavior of estuarine outflow plumes  

Microsoft Academic Search

We present results of dual-polarized radar scattering measurements of the Chesapeake Bay outflow plume. Near-unity polarization ratios (ratios of horizontally polarized radar echoes over vertically polarized ones) are observed in large incidence angle (60° to 80°) radar echoes from the outflow plume and its frontal boundary (normally referred to as a front) under strong surface current convergence (0.008-0.02 S-1), suggesting

Xuehu Zhang; Elizabeth M. Twarog; David J. McLaughlin; Mark A. Sletten; George O. Marmorino; Clifford L. Trump; Nicholas Allan

2004-01-01

344

Distributed robotics approach to chemical plume tracing  

Microsoft Academic Search

This paper presents an application of a physics-based framework for distributed control of autonomous vehicles. The autonomous swarm uses local information to self-organize into dynamic sensing and computation grids during localization of the source of a toxic plume. Using physics of fluid flow, we develop a new plume-tracing algorithm, and then use computational fluid dynamics simulations to show that the

Dimitri Zarzhitsky; Diana F. Spears; William M. Spears

2005-01-01

345

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

346

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

347

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

348

Endothermic and exothermic chemically reacting plumes  

NASA Astrophysics Data System (ADS)

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 reaction, where one species is present in the plume from a pure source and the other is in the environment. For uniform ambient density and species fields the reaction has an important effect on the deviation from pure plume behaviour as defined by the source parameter lazy’, whereas for an endothermic reaction this difference decreases and the plume is more jet-like. Furthermore, for chemical and density-stratified environments, the reaction will have an important effect on the buoyancy flux because the entrainment rate will not necessarily decrease with distance from the source, as in traditional models. As a result, the maximum rise height of the plume for exothermic reactions may actually decrease with reaction rate if this occurs in a region of high ambient density. In addition, we investigate non-Boussinesq effects, which are important when the heat of reaction is large enough.

Conroy, Devin T.; Smith, Stefan G. Llewellyn

349

[Positron emission tomography for volume delineation of pelvic nodal involvement].  

PubMed

Radiotherapy planification has recently known important developments, with the rise of new technologies, such as conformational radiation therapy, intensity-modulated radiation therapy (IMRT) or stereotaxic radiation therapy. Delineation of target volumes has become primordial. Hybrid imaging by positron emission tomography associated to computed tomography scanner (PET-CT) gives an access to functional and morphological information. Radiotherapist and nuclear physicians working closely have the potential to allow a more optimal delineation, and a better preservation of organs at risk. During the past few years, this has been explored by many articles, and we propose a literature review organized by localization, about the use of PET-CT for pelvic nodes delineation. PMID:23973459

Charrier, N; Brenot-Rossi, I

2013-10-01

350

A six degree of freedom, plume-fuel optimal trajectory planner for spacecraft proximity operations using an A* node search. M.S. Thesis - MIT  

NASA Technical Reports Server (NTRS)

Spacecraft proximity operations are complicated by the fact that exhaust plume impingement from the reaction control jets of space vehicles can cause structural damage, contamination of sensitive arrays and instruments, or attitude misalignment during docking. The occurrence and effect of jet plume impingement can be reduced by planning approach trajectories with plume effects considered. An A* node search is used to find plume-fuel optimal trajectories through a discretized six dimensional attitude-translation space. A plume cost function which approximates jet plume isopressure envelopes is presented. The function is then applied to find relative costs for predictable 'trajectory altering' firings and unpredictable 'deadbanding' firings. Trajectory altering firings are calculated by running the spacecraft jet selection algorithm and summing the cost contribution from each jet fired. A 'deadbanding effects' function is defined and integrated to determine the potential for deadbanding impingement along candidate trajectories. Plume costs are weighed against fuel costs in finding the optimal solution. A* convergence speed is improved by solving approach trajectory problems in reverse time. Results are obtained on a high fidelity space shuttle/space station simulation. Trajectory following is accomplished by a six degree of freedom autopilot. Trajectories planned with, and without, plume costs are compared in terms of force applied to the target structure.

Jackson, Mark Charles

1994-01-01

351

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

352

Identification of a reactive degradation zone at a landfill leachate plume fringe using high resolution sampling and incubation techniques.  

PubMed

Vertical small-scale variation in phenoxy acid herbicide degradation across a landfill leachate plume fringe was studied using laboratory degradation experiments. Sediment cores (subdivided into 5 cm segments) were collected in the aquifer and the sediment and porewater were used for microcosm experiments (50 experiments) and for determination of solid organic carbon, solid-water partitioning coefficients, specific phenoxy acid degraders and porewater chemistry. Results from a multi-level sampler installed next to the cores provided information on the plume position and oxygen concentration in the groundwater. Oxygen concentration was controlled individually in each microcosm to mimic the conditions at their corresponding depths. A highly increased degradation potential existed at the narrow plume fringe (37.7 to 38.6 masl), governed by the presence of phenoxy acids and oxygen. This resulted in the proliferation of a microbial population of specific phenoxy acid degraders, which further enhanced the degradation potential for phenoxy acids at the fringe. The results illustrate the importance of fringe degradation processes in contaminant plumes. Furthermore, they highlight the relevance of using high-resolution sampling techniques as well as controlled microcosm experiments in the assessment of the natural attenuation capacity of contaminant plumes in groundwater. PMID:16524640

Tuxen, Nina; Albrechtsen, Hans-Jørgen; Bjerg, Poul L

2006-05-30

353

Delineation of LASIK Flaps with Prednisolone Acetate Eyedrops  

PubMed Central

We describe the use and safety of prednisolone acetate eyedrops at the end of laser in situ keratomileusis (LASIK) to aid proper positioning of the corneal flap. The LASIK flap is created using the preferred technique. Following laser ablation and flap repositioning, one drop of prednisolone acetate is instilled on the eye. This delineates the flap “gutters” and allows perfect flap positioning and centration. We used this technique in 425 eyes undergoing LASIK for correction of spherocylindrical refractive errors. Flap margins were adequately delineated intraoperatively. The only complication related to the use of the steroid suspension was crystal deposition under the flap in one case which resolved completely in 48 hours.

Fahd, Daoud C; Fahed, Sharbel D

2014-01-01

354

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

355

The deep scattering layer associated with the Endeavour Ridge hydrothermal plume  

NASA Astrophysics Data System (ADS)

We analyse surface-to-bottom profiles of temperature, salinity, light attenuation coefficient and acoustic (150 kHz) backscatter intensity collected in June 1990 in the vicinity of the central hydrothermal vent field on Endeavour Ridge in the northeast Pacific. Data from coincident deep plankton net tows corroborate earlier speculation (Thomson et al., 1991, Journal of Geophysical Research, 96, 4839-4844) that the 100 m thick acoustic scattering layer found near 1.9 km depth in this region consists of a dense concentration of macrozooplankton living near the top of the plume-contaminated bottom waters. Peak (?10 dB) acoustic anomalies in the June 1990 backscatter layer were located near the top of the plume at depths of 1800-2000 m throughout the principal 60 km 2 study area. The scattering layer contained a high Zooplankton biomass of 21 mg m -3 and maximum species richness of 83 taxa. In all profiles, the backscatter intensity decreased to anomalously low values beneath the core of the plume. The presence of the backscatter layer 12 km to the east of the vent site is evidence for Zooplankton layering beyond the immediate confines of the ridge. We conclude that pelagic and deep-sea Zooplankton congregate near the top of the plumecontaminated bottom waters in the vicinity of the ridge to take advantage of increased concentrations of chemosynthetic bacteria, fine-grained particles and other nutrients carried vertically upward by the buoyant portions of the plume. The Zooplankton depletion below the central core of the spreading hydrothermal plume indicates that Zooplankton avoid elevated concentrations of hydrothermally-derived minerals and other chemicals inherent to the main body of the plume.

Thomson, Richard E.; Burd, Brenda J.; Dolling, Adrian G.; Lee Gordon, R.; Jamieson, Glen S.

1992-01-01

356

The planet beyond the plume hypothesis  

NASA Astrophysics Data System (ADS)

Acceptance of the theory of plate tectonics was accompanied by the rise of the mantle plume/hotspot concept which has come to dominate geodynamics from its use both as an explanation for the origin of intraplate volcanism and as a reference frame for plate motions. However, even with a large degree of flexibility permitted in plume composition, temperature, size, and depth of origin, adoption of any limited number of hotspots means the plume model cannot account for all occurrences of the type of volcanism it was devised to explain. While scientific protocol would normally demand that an alternative explanation be sought, there have been few challenges to "plume theory" on account of a series of intricate controls set up by the plume model which makes plumes seem to be an essential feature of the Earth. The hotspot frame acts not only as a reference but also controls plate tectonics. Accommodating plumes relegates mantle convection to a weak, sluggish effect such that basal drag appears as a minor, resisting force, with plates having to move themselves by boundary forces and continents having to be rifted by plumes. Correspondingly, the geochemical evolution of the mantle is controlled by the requirement to isolate subducted crust into plume sources which limits potential buffers on the composition of the MORB-source to plume- or lower mantle material. Crustal growth and Precambrian tectonics are controlled by interpretations of greenstone belts as oceanic plateaus generated by plumes. Challenges to any aspect of the plume model are thus liable to be dismissed unless a counter explanation is offered across the geodynamic spectrum influenced by "plume theory". Nonetheless, an alternative synthesis can be made based on longstanding petrological evidence for derivation of intraplate volcanism from volatile-bearing sources (wetspots) in conjunction with concepts dismissed for being incompatible or superfluous to "plume theory". In the alternative Earth, the sources for intraplate volcanism evolve from the source residues of arc volcanism located along sutures in the continental mantle. Continental rifting and the lateral distribution of intraplate sources in the asthenosphere are controlled by Earth rotation. Shear induced on the base of the asthenosphere from the mesosphere as the Earth rotates is transmitted to the lithosphere as basal drag. Attenuation of the drag due to the low viscosity of the asthenosphere, in conjunction with plate motions from boundary forces, results in a rotation differential of up to 5 cm yr -1 between the lithosphere and mesosphere manifest as westward plate lag/eastward mantle flow. Continental rifting results from basal drag supplemented by local convection induced by lithospheric architecture. Large continental igneous provinces are generated by convective melting, with passive margin volcanic sequences following the axis of rifting and flood basalts overlying the intersection of sutures in the continental mantle. As rifting progresses, the convection cells expand, cycling continental mantle from sutures perpendicular to the rift axis to generate intraplate tracks in the ocean basin. Continental mantle not melted on rifting, or delaminated on continental collision, becomes displaced to the east of the continent by differential rotation, which also sets up a means for tapping the material to give fixed melting anomalies. When plates move counter to the Earth's rotation, as in the example of the Pacific plate, asthenospheric flow is characterised by a counterflow regime with a zero velocity layer at depths within the stability field for volatile-bearing minerals. Intraplate volcanism results when melts are tapped from this stationary layer along lithospheric stress trajectories induced by stressing of the plate from variations in the subduction geometry around the margins of the plate. Plate boundary forces acting in the same direction as Earth rotation, as for the Nazca plate, produce fast plate velocities but not counterflow, though convergent margin geometry may

Smith, Alan D.; Lewis, Charles

1999-12-01

357

Forecasting low-latitude radio scintillation with 3-D ionospheric plume models: 1. Plume model  

Microsoft Academic Search

A three-dimensional model has been developed for the plasma plumes caused by interchange instabilities in the low-latitude ionosphere to describe the structure and extent of the radio scintillation generated by turbulence in and around the plumes (down to the scale sizes resolvable by the computer model). With the inclusion of the processes that determine the transport of plasma parallel to

J. M. Retterer

2010-01-01

358

ENVIRONMENTAL RESEARCH BRIEF: INNOVATIVE MEASURES FOR SUBSURFACE CHROMIUM REMEDIATION: SOURCE ZONE, CONCENTRATED PLUME, AND DILUTE PLUME.  

EPA Science Inventory

This environmental research brief reports on innovative measures for addressing 1) the source zone soils, 2) the concentrated portion of the ground-water plume, and 3) the dilute portion of the ground-water plume. For the source zone, surfactant-enhanced chromium extraction is ev...

359

African Equatorial and Subtropical Ozone Plumes: Recurrences Timescales of the Brown Cloud Trans-African Plumes and Other Plumes  

NASA Technical Reports Server (NTRS)

We have found repeated illustrations in the maps of Total Tropospheric Ozone (TTO) of apparent transport of ozone from the Indian Ocean to the Equatorial Atlantic Ocean. Most interesting are examples that coincide with the INDOEX observations of late northern winter, 1999. Three soundings associated with the SHADOZ (Southern Hemisphere Additional Ozonesondes) network help confirm and quantify degree of influence of pollution, lightning, and stratospheric sources, suggesting that perhaps 40% of increased Atlantic ozone could be Asian pollution during periods of maximum identified in the TTO maps. We outline recurrent periods of apparent ozone transport from Indian to Atlantic Ocean regions both during and outside the late-winter period. These are placed in the context of some general observations about factors controlling recurrence timescales for the expression of both equatorial and subtropical plumes. Low-level subtropical plumes are often controlled by frontal systems approaching the Namib coast; these direct mid-level air into either easterly equatorial plumes or westerly mid- troposphere plumes. Equatorial plumes of ozone cross Africa on an easterly path due to the occasional coincidence of two phenomena: (1) lofting of ozone to mid and upper levels, often in the Western Indian Ocean, and (2) the eastward extension of an Equatorial African easterly jet.

Chatfield, Robert B.; Thompson, Anne M.; Guan, Hong; Witte, Jacquelyn C.

2004-01-01

360

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

361

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

362

Superfund record of decision (EPA Region 9): Newmark Groundwater Contamination Site, San Bernardino, CA, August 1993  

SciTech Connect

This decision document presents the selected remedial action for the Newmark Operable Unit, Newmark Groundwater Contamination Superfund site. EPA has selected an interim remedy for the Newmark plume of groundwater contamination in the Newmark Groundwater Contamination Superfund Site. This portion of the site cleanup is referred to as the Newmark Operable Unit (OU). The Newmark OU is an interim action focusing on contamination in the undergound water supply in the Bunker Hill Basin of San Bernardino, north and east of the Shandin Hills.

Not Available

1993-08-04

363

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

364

Ichthyosis bullosa of Siemens: Further delineation of the phenotype  

Microsoft Academic Search

We report a third family affected with ichthyosis bullosa of Siemens, and we further delineate the clinical spectrum of this mild type of epidermolytic hyperkeratosis. Erythroderma had never been present in any of the affected individuals. All of them exhibited a brownish, rimpled hyperkeratosis, the main characteristic sites being the joints, the shins and the periumbilical region. Blistering occurred after

P. M. Steijlen; C. M. Perret; J. H. Schuurmans Stekhoven; D. J. Ruiter; R. Happle

1990-01-01

365

Watershed delineation from the medial axis of river networks  

NASA Astrophysics Data System (ADS)

The watersheds are commonly delineated from digital elevation models (DEM). This approach is not efficient when an accurate DEM is not available. Furthermore, since raster-based algorithms are employed, the computations for large areas are very time consuming and even may be impractical. This article investigates delineation of the watersheds from the medial axis of river networks: If the river network is sampled by a set of points, the medial axis of the sample points provides an approximation of the catchments, whose aggregation results in the watersheds. Although this idea has been already proposed in the literature, the complexities of the medial axis extraction prevent it from being practically used. A major issue is appearing extraneous branches in the media axis due to perturbations of the sample points, which must be filtered out in a pre- or post-processing step. This article improves a Voronoi-based medial axis extraction algorithm by using labeled sample points to automatically avoid extraneous branches. The proposed method is used in four case studies to delineate the watersheds. The results illustrate that the proposed method is stable, easy to implement and robust, even in presence of significant noises and perturbations. The results also indicate that the watersheds delineated using the proposed and the DEM-based methods are reasonably comparable.

Karimipour, Farid; Ghandehari, Mehran; Ledoux, Hugo

2013-09-01

366

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

367

Automated delineation of coastline from polarimetric SAR imagery  

Microsoft Academic Search

In this paper we present a new diffusion-based method for the delineation of coastlines from space-borne polarimetric SAR imagery of coastal urban areas. Both polarimetric filtering and speckle reducing anisotropic diffusion (SRAD) are exploited to generate a base image where speckle is reduced and edges are enhanced. The primary edge information is then derived from the base image using the

Y. Yu

2004-01-01

368

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.

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

2014-01-01

369

385. Delineator Unknown December 1932 STATE OF CALIFORNIA; DEPARTMENT OF ...  

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

385. Delineator Unknown December 1932 STATE OF CALIFORNIA; DEPARTMENT OF PUBLIC WORKS; SAN FRANCISCO - OAKLAND BAY BRIDGE; SUPERSTRUCTURE - WEST BAY CROSSING; ROCKER POSTS AND BEARING; CONTRACT NO. 6; DRAWINGS NO. 42 - San Francisco Oakland Bay Bridge, Spanning San Francisco Bay, San Francisco, San Francisco County, CA

370

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...

371

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

372

Follow the plume: the habitability of enceladus.  

PubMed

The astrobiological exploration of other worlds in our Solar System is moving from initial exploration to more focused astrobiology missions. In this context, we present the case that the plume of Enceladus currently represents the best astrobiology target in the Solar System. Analysis of the plume by the Cassini mission indicates that the steady plume derives from a subsurface liquid water reservoir that contains organic carbon, biologically available nitrogen, redox energy sources, and inorganic salts. Furthermore, samples from the plume jetting out into space are accessible to a low-cost flyby mission. No other world has such well-studied indications of habitable conditions. Thus, the science goals that would motivate an Enceladus mission are more advanced than for any other Solar System body. The goals of such a mission must go beyond further geophysical characterization, extending to the search for biomolecular evidence of life in the organic-rich plume. This will require improved in situ investigations and a sample return. PMID:24684187

McKay, Christopher P; Anbar, Ariel D; Porco, Carolyn; Tsou, Peter

2014-04-01

373

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

374

Crater Formation Due to Lunar Plume Impingement  

NASA Technical Reports Server (NTRS)

Thruster plume impingement on a surface comprised of small, loose particles may cause blast ejecta to be spread over a large area and possibly cause damage to the vehicle. For this reason it is important to study the effects of plume impingement and crater formation on surfaces like those found on the moon. Lunar soil, also known as regolith, is made up of fine granular particles on the order of 100 microns.i Whenever a vehicle lifts-off from such a surface, the exhaust plume from the main engine will cause the formation of a crater. This crater formation may cause laterally ejected mass to be deflected and possibly damage the vehicle. This study is a first attempt at analyzing the dynamics of crater formation due to thruster exhaust plume impingement during liftoff from the moon. Though soil erosion on the lunar surface is not considered, this study aims at examining the evolution of the shear stress along the lunar surface as the engine fires. The location of the regions of high shear stress will determine where the crater begins to form and will lend insight into how big the crater will be. This information will help determine the probability that something will strike the vehicle. The final sections of this report discuss a novel method for studying this problem that uses a volume of fluid (VOF)ii method to track the movement of both the exhaust plume and the eroding surface.

Marsell, Brandon

2011-01-01

375

Source identification and hazardous risk delineation of heavy metal contamination in Yanqi basin, northwest China.  

PubMed

A total of 469 surface soil samples were collected from the Yanqi basin in northwest China and evaluated for levels of ten heavy metals. Multivariate statistical analyses were used to study sources of and map the spatial distribution of heavy metals, as well as determine the relationship between land use types and soil source materials. It was found that: (1) the average amounts of ten heavy metals in the Yanqi basin were all below the national soil environmental quality standards of China (GB15618-1998), but the average amount of Cd, Hg, Mn, Ni, Pb, and Zn all exceeded the heavy metal background levels of soil in Xinjiang, China and exhibited accumulation. The ten heavy metals analyzed in this study can be categorized into four principal components as follows: Principal component 1 was Co, Cr, Mn, Ni, and Zn, and principal component 3 was As and Cu. Both of these originated from a natural geological background. Principal component 2 consisted of Cd and Pb and originated from industrial, agricultural and transportation influences. Principal component 4 consisted of Hg and was due to industrial influences. Our study found that Pb and Zn were a large part in the principal components 1 and 3 and were influenced by a combination of geologic background and human activity. (2) Heavy metals Cd and Hg were at high levels in construction land and farmland, while Co, Cr, Cu, Mn, and Ni were significantly higher in lacustrine deposits than in sandy shale from weathered material, coarse crystalline rock weathered material, and diluvial material. The land use types correlated significantly with the accumulation of Cd and Hg, and the soil parent material was the major factor for the accumulation of As, Co, Cr, Cu, Mn, and Ni. (3) The single element, element integration and the corresponding principal component presented similar spatial patterns of hazardous risk. Following comprehensive assessment of all elements, the high risk regions were found to be located in densely-populated urban areas and western parts of the study area. This was attributed to the higher geological background in the western part and strong human influence in the central part. Research shows that Cd, Hg, Pb, and Zn were locally enriched in the basin and this warrants increased attention. PMID:24953685

Mamat, Zulpiya; Yimit, Hamid; Ji, Rou Zi A; Eziz, Mamattursun

2014-09-15

376

INTEGRATED APPROACH TO DELINEATE THE CONTAMINATED GROUNDWATER IN THE TENNARY BELT: A CASE STUDY  

Microsoft Academic Search

The study area is situated in the upper Kodaganar river basin, Tamilnadu, India. There are about 80 functional tanneries. The untreated effluents from these tanneries have considerably affected the quality of groundwater. In order to assess the extent of groundwater deterioration (quality), hydrogeological, geophysical and hydrochemical studies were carried out. 37 Schlumberger Vertical Electrical Soundings (VES) and two electrical imagings

N. C. MONDAL; V. S. SINGH

377

Delineation of Water and Sediment Contamination in River Near a Coal Ash Pond in Orissa, India  

Microsoft Academic Search

High concentrations of trace elements, and in most cases, their enrichment were observed in water in the post-monsoon river water in the vicinity of a coal ash disposal site. Aluminum, Fe, Mn and Pb concentrations were found enriched to varying degrees and exceeded the respective maximum permissible limits prescribed for drinking water. The concentrations of elements increased in the downstream

S. Tripathy; T. Praharaj

378

Public health assessment for Odessa Superfund Site (a/k/a Sprague Road Groundwater Plume) Ector, Ector County, Texas, Region 6: CERCLIS number TX0001407444. Final report  

SciTech Connect

The Sprague Road Groundwater Plume National Priorities List site, consists of three plumes of chromium contaminated water just outside the northern city limits of Odessa, Ector County, Texas. The chromium in the groundwater is a public health hazard to people who continue to use the chromium-contaminated water wells for drinking. Chromium in soil at Leigh Metal Plating Inc. presents a potential public health hazard. Although this facility is surrounded by a fence, access to the site is not entirely restricted. There is a five-foot pit on the National Chromium Corporation site that could present a physical hazard to children trespassing on the site.

NONE

1998-12-28

379

Combining a finite mixture distribution model with indicator kriging to delineate and map the spatial patterns of soil heavy metal pollution in Chunghua County, central Taiwan.  

PubMed

This study identifies the natural background, anthropogenic background and distribution of contamination caused by heavy metal pollutants in soil in Chunghua County of central Taiwan by using a finite mixture distribution model (FMDM). The probabilities of contaminated area distribution are mapped using single-variable indicator kriging and multiple-variable indicator kriging (MVIK) with the FMDM cut-off values and regulation thresholds for heavy metals. FMDM results indicate that Cr, Cu, Ni and Zn can be individually fitted by a mixture model representing the background and contamination distributions of the four metals in soil. The FMDM cut-off values for contamination caused by the metals are close to the regulation thresholds, except for the cut-off value of Zn. The receiver operating characteristic (ROC) curve validates that indicator kriging and MVIK with FMDM cut-off values can reliably delineate heavy metals contamination, particularly for areas lacking background information and high heavy metal concentrations in soil. PMID:19665827

Lin, Yu-Pin; Cheng, Bai-You; Shyu, Guey-Shin; Chang, Tsun-Kuo

2010-01-01

380

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

381

Plume head - trench interaction: impact on subduction dynamics  

NASA Astrophysics Data System (ADS)

The geologic record provides numerous examples where plumes and their associated buoyancy swell have disrupted convergent plate margins. These interactions have produced a variety of responses in the overriding plate including transient episodes of arc amagmatism, transient episodes of crustal shortening followed by plume-related magmatism in the overriding plate. The latter observation implies the plume must have transitioned from the subducting plate to the overriding plate. We present several 3D Underworld numerical models of plume heads of variable dimension and buoyancy interacting with a subduction trench. The models indicate that plume heads impact enormously on trench geometry. Arcuate trenches are created as the trench retreats around the edges of the plume head, whereas trench advance occurs in front of the plume resulting in transient crustal shortening in the overriding plate. Stalling of subduction when the plume head impacts the trench causes slab windowing. The size of the slab window is dependent on the size and buoyancy of the plume. The creation of the slab window provides a potential conduit for plume migration to the overriding plate. Alternatively, the plume head may be transferred to the overriding plate as subduction is re-established behind the plume. Models with "strong" slabs, characterized by high yield strengths, display different behavior. Plume-heads are entrained in the slab and are subducted without the development of a slab window.

Betts, P. G.; Moresi, L. N.; Mason, W. G.; Willis, D.

2013-12-01

382

Winds and the orientation of a coastal plane estuary plume  

NASA Astrophysics Data System (ADS)

Based on a calibrated coastal plane estuary plume model, ideal model hindcasts of estuary plumes are used to describe the evolution of the plume pattern in response to river discharge and local wind forcing by selecting a typical partially mixed estuary (the Cape Fear River Estuary or CFRE). With the help of an existing calibrated plume model, as described by Xia et al. (2007), simulations were conducted using different parameters to evaluate the plume behavior type and its change associated with the variation of wind forcing and river discharge. The simulations indicate that relatively moderate winds can mechanically reverse the flow direction of the plume. Downwelling favorably wind will pin the plume to the coasts while the upwelling plume could induce plume from the left side to right side in the application to CFRE. It was found that six major types of plumes may occur in the estuary and in the corresponding coastal ocean. To better understand these plumes in the CFRE and other similar river estuary systems, we also investigated how the plumes transition from one type to another. Results showed that wind direction, wind speed, and sometimes river discharge contribute to plume transitions.

Xia, Meng; Xie, Lian; Pietrafesa, Leonard J.

2010-10-01

383

Conversion rates in power plant plumes based on filter pack data: The oil fired Northport plume  

NASA Astrophysics Data System (ADS)

More than 60 airborne plume studies were conducted at a large oil fired power station during a 3 build1/2 year period. These studies were conducted to determine the typical rate of formation of sulfate in the plume and the conditions which most influence these atmospheric processes. The power plant chosen for this program is located in the northeast region of the U.S. and during the course of these studies a typical variety of meteorological conditions were encountered. This is probably the most extensive body of plume data ever gathered from a single power plant. The effect on the oxidation rate was explored for a wide variety of and variation in meteorological conditions. Plume sulfate rarely accounted for more than 5 % of the total plume sulfur even for plume travel times of up to 4 h. For most experiments more than half of the observed plume sulfate was that emitted from the power plant units. The rate of atmospheric oxidation of sulfur dioxide to sulfate was not readily discernible due to the low rate of conversion and the relatively high amount of the sulfate emitted. The results reported in this paper generally indicate an apparent oxidation rate of less than 1 % h -. A diurnal influence or effects due to changes in various meteorological conditions are difficult to discern.

Garber, Robert W.; Forrest, Joseph; Newman, Leonard

384

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

385

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

386

Effects of meteorological conditions on spore plumes  

NASA Astrophysics Data System (ADS)

Fungal spores are an ever-present component of the atmosphere, and have long been known to trigger asthma and hay fever symptoms in sensitive individuals. The atmosphere around Tulsa has been monitored for airborne spores and pollen with Burkard spore traps at several sampling stations. This study involved the examination of the hourly spore concentrations on days that had average daily concentrations near 50,000 spores/m3 or greater. Hourly concentrations of Cladosporium, Alternaria, Epicoccum, Curvularia, Pithomyces, Drechslera, smut spores, ascospores, basidiospores, other, and total spores were determined on 4 days at three sites and then correlated with hourly meteorological data including temperature, rainfall, wind speed, dew point, air pressure, and wind direction. On each of these days there was a spore plume, a phenomenon in which spore concentrations increased dramatically over a very short period of time. Spore plumes generally occurred near midday, and concentrations were seen to increase from lows around 20,000 total spores/m3 to highs over 170,000 total spores/m3 in 2 h. Multiple regression analysis of the data indicated that increases in temperature, dew point, and air pressure correlated with the increase in spore concentrations, but no single weather variable predicted the appearance of a spore plume. The proper combination of changes in these meteorological parameters that result in a spore plume may be due to the changing weather conditions associated with thunderstorms, as on 3 of the 4 days when spore plumes occurred there were thunderstorms later that evening. The occurrence of spore plumes may have clinical significance, because other studies have shown that sensitization to certain spore types can occur during exposure to high spore concentrations.

Burch, M.; Levetin, E.

2002-05-01

387

Effects of meteorological conditions on spore plumes.  

PubMed

Fungal spores are an ever-present component of the atmosphere, and have long been known to trigger asthma and hay fever symptoms in sensitive individuals. The atmosphere around Tulsa has been monitored for airborne spores and pollen with Burkard spore traps at several sampling stations. This study involved the examination of the hourly spore concentrations on days that had average daily concentrations near 50,000 spores/m(3) or greater. Hourly concentrations of Cladosporium, Alternaria, Epicoccum, Curvularia, Pithomyces, Drechslera, smut spores, ascospores, basidiospores, other, and total spores were determined on 4 days at three sites and then correlated with hourly meteorological data including temperature, rainfall, wind speed, dew point, air pressure, and wind direction. On each of these days there was a spore plume, a phenomenon in which spore concentrations increased dramatically over a very short