Note: This page contains sample records for the topic contaminant plume delineation from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: November 12, 2013.
1

Waste and cost reduction using dual wall reverse circulation drilling with multi-level groundwater sampling for contaminant plume delineation.  

National Technical Information Service (NTIS)

This paper describes the drilling and sampling methods used to delineate a groundwater contaminant plume at the Paducah Gaseous Diffusion Plant (PGDP) during the Groundwater Monitoring IV characterization. The project was unique in that it relied upon dua...

D. R. Smuin

1995-01-01

2

Delineation of contamination plume around oxidation sewage-ponds in Southwestern Nigeria  

NASA Astrophysics Data System (ADS)

Integrated surface electrical resistivity and electromagnetic (EM) surveys were conducted in a hard-rock terrain of Southwestern Nigeria in the vicinity of active oxidation sewage treatment ponds. The aim was to detect soil contamination due to the spread of sewage effluent, locate possible leachate plumes and conductive lithologic layers, and access the risk of groundwater pollution in the vicinity of the sewage-ponds. Dipole-dipole resistivity profiling and very low frequency (VLF) data were acquired at 10-m intervals along five 200-m long east-west geophysical traverses. Resistivity sections obtained revealed four subsurface geologic layers comprised of lateritic clay, clayey sand/sand, weathered/fractured bedrock, and competent bedrock. A distinct low resistivity zone corresponding to the contamination plume (labeled B) was delineated from all the resistivity sections. This low zone extends into the weathered bedrock and possibly suggests contamination of this layer. The filtered real component of the processed VLF data detected three distinct anomaly zones that are representative of fractured zones filled with conductive fluids and/or lithologic boundaries that possibly serve as conduits for the movement of contaminated effluents. The results obtained from the two methods suggest possible contamination of the subsurface soil layers and groundwater in the vicinity of the sewage-ponds. The existence of this contaminated plume poses a serious threat to the ecosystem and health of the people living in the vicinity of the sewage-ponds.

Adepelumi, A. A.; Ako, B. D.; Afolabi, O.; Arubayi, J. B.

2005-10-01

3

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

NASA Astrophysics Data System (ADS)

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 O2 rich recharge water were important O2 transport mechanisms.

Amos, Richard T.; Bekins, Barbara A.; Delin, Geoffrey N.; Cozzarelli, Isabelle M.; Blowes, David W.; Kirshtein, Julie D.

2011-07-01

4

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

PubMed

High resolution direct-push profiling over short vertical distances was used to investigate CH(4) 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 CH(4) and CO(2), and the presence of methanotrophic bacteria. Sharp redox gradients were observed near the water table. Shifts in ?(13)C(CH4) from an average of -57.6‰ (±1.7‰) in the methanogenic zone to -39.6‰ (±8.7‰) at 105m downgradient, strongly suggest CH(4) attenuation through microbially mediated degradation. In the downgradient zone the aerobic/anaerobic transition is up to 0.5m below the water table suggesting that transport of O(2) across the water table is leading to aerobic degradation of CH(4) at this interface. Dissolved N(2) concentrations that exceeded those expected for water in equilibrium with the atmosphere indicated bubble entrapment followed by preferential stripping of O(2) through aerobic degradation of CH(4) 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 O(2) transport mechanisms. PMID:21612840

Amos, Richard T; Bekins, Barbara A; Delin, Geoffrey N; Cozzarelli, Isabelle M; Blowes, David W; Kirshtein, Julie D

2011-04-27

5

Plume Delineation Exercise  

NSDL National Science Digital Library

This exercise is designed to develop students ability to synthesize subsurface data and develop a model to explain a local groundwater contamination issue. Based on their groundwater model, they will make predictions as to location of the source area and the location of any potential human health risk. The exercise requires basic contour mapping skill, simple mathematical problem solving skills and a knowledge of Darcy's Law. Has minimal/no quantitative component

Lev, Steven

6

Characterization of a Landfill-Derived Contaminant Plume in Glacial and Bedrock Aquifers, NE Illinois.  

National Technical Information Service (NTIS)

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 rel...

C. J. Booth P. J. Vagt

1986-01-01

7

Groundwater contaminant plume ranking.  

National Technical Information Service (NTIS)

Containment plumes at Uranium Mill Tailings Remedial Action (UMTRA) Project sites were ranked to assist in Subpart B (i.e., restoration requirements of 40 CFR Part 192) compliance strategies for each site, to prioritize aquifer restoration, and to budget ...

1988-01-01

8

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

National Technical Information Service (NTIS)

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 aug...

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

1995-01-01

9

Plume Delineation in the BC Cribs and Trenches Area  

SciTech Connect

HydroGEOPHYSICS, Inc. and Pacific Northwest National Laboratory (PNNL) were contracted by Fluor Hanford Group, Inc. to conduct a geophysical investigation in the area of the BC Cribs and Trenches (subject site) at the Hanford Site in Richland, Washington. The BC Cribs and Trenches are located south of the 200 East Area. This document provides the details of the investigation to identify existing infrastructure from legacy disposal activities and to delineate the edges of a groundwater plume that contains radiological and heavy metal constituents beneath the 216-B-26 and 216-B-52 Trenches, and the 216-B-14 through 216-B-19 Cribs.

Rucker, Dale F.; Sweeney, Mark D.

2004-11-30

10

Microbial populations in contaminant plumes  

USGS Publications Warehouse

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.

Haack, S. K.; Bekins, B. A.

2000-01-01

11

Monitoring groundwater contamination and delineating source zones at industrial sites: Uncertainty analyses using integral pumping tests  

Microsoft Academic Search

Field-scale characterisations of contaminant plumes in groundwater, as well as source zone delineations, are associated with uncertainties that can be considerable. A major source of uncertainty in environmental datasets is due to variability of sampling results, as a direct consequence of the heterogeneity of environmental matrices. We develop a methodology for quantifying uncertainties in field-scale mass flow and average concentration

Jerker Jarsjö; Martí Bayer-Raich; Thomas Ptak

2005-01-01

12

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.

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

Groundwater redox conditions and conductivity in a contaminant plume from geoelectrical investigations  

Microsoft Academic Search

Accurate mapping of the electrical conductivity and of the redox potential of the groundwater is important in delineating the shape of a contaminant plume. A map of redox potential in an aquifer is indicative of biodegradation of organic matter and of concentrations of redox-active components; a map of electrical conductivity provides information on the mineralisation of the groundwater. Both maps

V. Naudet; A. Revil; E. Rizzo; J.-Y. Bottero; P. Bégassat

2004-01-01

15

Space-time correlation models and contaminant plumes  

Microsoft Academic Search

SUMMARY A contaminant plume might be described by a function defined in space-time. Spatial integrals or time derivatives of this function as well as time derivatives of spatial integrals will quantify characteristics such as the total volume of the plume, the total concentration of the contaminant in the plume, rates of change of the volume, and rates of change of

D. E. Myers

2002-01-01

16

Groundwater contaminant plume ranking. [UMTRA Project  

SciTech Connect

Containment plumes at Uranium Mill Tailings Remedial Action (UMTRA) Project sites were ranked to assist in Subpart B (i.e., restoration requirements of 40 CFR Part 192) compliance strategies for each site, to prioritize aquifer restoration, and to budget future requests and allocations. The rankings roughly estimate hazards to the environment and human health, and thus assist in determining for which sites cleanup, if appropriate, will provide the greatest benefits for funds available. The rankings are based on the scores that were obtained using the US Department of Energy's (DOE) Modified Hazard Ranking System (MHRS). The MHRS and HRS consider and score three hazard modes for a site: migration, fire and explosion, and direct contact. The migration hazard mode score reflects the potential for harm to humans or the environment from migration of a hazardous substance off a site by groundwater, surface water, and air; it is a composite of separate scores for each of these routes. For ranking the containment plumes at UMTRA Project sites, it was assumed that each site had been remediated in compliance with the EPA standards and that relict contaminant plumes were present. Therefore, only the groundwater route was scored, and the surface water and air routes were not considered. Section 2.0 of this document describes the assumptions and procedures used to score the groundwater route, and Section 3.0 provides the resulting scores for each site. 40 tabs.

Not Available

1988-08-01

17

Contaminant plume classification system based on mass discharge.  

PubMed

Estimation of mass discharge has become an increasingly valuable analysis technique at sites with contaminated groundwater plumes. We propose a simple plume magnitude classification system based on mass discharge comprised of 10 separate magnitude categories, such as a "Mag 7 plume." This system can be a useful tool for scientists, engineers, regulators, and stakeholders to better communicate site conceptual models, prioritize sites, evaluate plumes both spatially and temporally, and determine potential impacts. PMID:21306359

Newell, Charles J; Farhat, Shahla K; Adamson, David T; Looney, Brian B

2011-02-09

18

Uncertainty assessment of contaminant plume length estimates in heterogeneous aquifers.  

PubMed

The Virtual Aquifer approach is used in this study to assess the uncertainty involved in the estimation of contaminant plume lengths in heterogeneous aquifers. Contaminant plumes in heterogeneous two-dimensional conductivity fields and subject to first order and Michaelis-Menten (MM) degradation kinetics are investigated by the center line method. First order degradation rates and plume lengths are estimated from point information obtained along the plume center line. Results from a Monte-Carlo investigation show that the estimated rate constant is highly uncertain and biased towards overly high values. Uncertainty and bias amplify with increasing heterogeneity up to maximum values of one order of magnitude. Calculated plume lengths reflect this uncertainty and bias. On average, plume lengths are estimated to about 50% of the true plume length. When plumes subject to MM degradation kinetics are investigated by using a first order rate law, an additional error is introduced and uncertainty as well as bias increase, causing plume length estimates to be less than 40% of the true length. For plumes with MM degradation kinetics, therefore, a regression approach is used which allows the determination of the MM parameters from center line data. Rate parameters are overestimated by a factor of two on average, while plume length estimates are about 80% of the true length. Plume lengths calculated using the MM parameters are thus closer to the correct length, as compared to the first order approximation. This approach is therefore recommended if field data collected along the center line of a plume give evidence of MM kinetics. PMID:16781794

Beyer, Christof; Bauer, Sebastian; Kolditz, Olaf

2006-06-16

19

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

USGS Publications Warehouse

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

Rubin, H.; Buddemeier, R. W.

2002-01-01

20

Limitations in recovering the history of a groundwater contaminant plume  

Microsoft Academic Search

Groundwater contaminant transport is a dispersive process and consequently there are limits to what may be learned about a contaminant's origins (history) from measurements of its present spatial distribution. The extent of these limitations in a particular case depends on a number of factors, including the dispersive properties of the transport medium, the accuracy of the measured plume, and the

Todd H. Skaggs; Z. J. Kabala

1998-01-01

21

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

22

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

NASA Astrophysics Data System (ADS)

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

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

2012-08-01

23

Advanced QCM controller for NASA's plume impingement contamination-II  

NASA Astrophysics Data System (ADS)

Currently, no accurate models or recent data exist for modeling contamination from spacecraft thrusters to meet the stringent requirements of the International Space Station (ISS). Few flight measurements of contaminant deposition from spacecraft thrusters have been made, and no measurements have been made for angles away from the plume centerline. The Plume Impingement Contamination-II (PIC-II) experiment is planned to provide such measurements using quartz crystal microbalances placed into the plume of a Shuttle Orbiter RCS thruster. To this end, the Johns Hopkins University Applied Physics Laboratory (APL) has supported NASA in the development of the PIC-II experiment Flight Electronics Unit known as the Remote Arm TQCM System (RATS), which will measure the contamination in the Shuttle Obiter RCS thruster. The development was based on an ongoing effort between the APL and QCM Research to develop an inexpensive, miniature TQCM controller based on a legacy of QCM controllers developed at the APL. PIC-II will provide substantial improvements over previous systems, including higher resolution, greater flexibility, intensive housekeeping, and in-situ operational control. Details of the experiment hardware and measurement technique are given. The importance of the experiment to the ISS and the general plume contamination community is discussed.

Cain, Russell P.; Lumpkin, Forrest E.; Carkhuff, Bliss G.; Wallace, Scott A.; Uy, O. Manuel

2002-09-01

24

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

USGS Publications Warehouse

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

Rubin, H.; Buddemeier, R. W.

2002-01-01

25

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

PubMed

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

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

2005-11-17

26

Chaotic Advection, Fluid Spreading, and Groundwater Contaminant Plumes  

NASA Astrophysics Data System (ADS)

In situ remediation of contaminated groundwater requires degradation reactions at the interface between the contaminant plume and an injected treatment solution containing chemical or biological amendments. Therefore a promising approach to accelerate in situ remediation is to elongate the interface between the contaminant plume and treatment solution through fluid spreading. The literature on chaotic advection describes how to accomplish spreading in laminar flows, which lack the turbulent eddies that provide spreading in streams or engineered reactors. A key result from the literature on chaotic advection is that spreading is inherent in the vicinity of certain periodic points, which are points to which fluid particles return in successive iterations of chaotic flows. Specifically, spreading is enhanced near the stable and unstable manifolds associated with hyperbolic periodic points. We investigate the transient flow created with a four-well system in which wells are operated sequentially as either injection wells or extraction wells. In particular, we identify the periodic points and demonstrate that fluid spreading occurs nearby. For appropriately designed injection and extraction sequences, the periodic points are located near the interface between the contaminant plume and treatment solution, leading to elongation of the interface, with expected benefits of enhanced reaction and accelerated remediation.

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

2011-12-01

27

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...

28

FIELD SOIL GAS SCREENING METHODS FOR THE DELINEATION OF SUBSUR- FACE CONTAMINATION  

Microsoft Academic Search

Delineation and remediation of subsurface contamination have become a major focus of envi ronmental science during the past five years. Conventional technologies available for subsurface investigations (e.g. monitoring wells) always will be required to confirm and monitor subsurface contamination; however, quicker and less expensive techniques are useful for preliminary site evaluations. Soil-gas surveying is a technique that is applicable to

MATTHIAS EISWIRTH; BARBARA REICHERT

29

Experimental Measurements of Expected Mass Fraction in a Contaminant Plume  

NASA Astrophysics Data System (ADS)

The sudden release of a quantity of gas into the atmospheric boundary layer produces a contaminant cloud. The expected mass fraction function provides a relatively simple measure of the contaminant concentration values found within the cloud and represents the ensemble-averaged fraction of the conserved release mass found at the different contaminant concentration intervals as the cloud evolves. The plume generated by a line source in grid turbulence is used to investigate the expected mass fraction function as it applies to scalar concentration values found on a typical line normal to the plume axis. Simultaneous particle image velocimetry and planar laser induced fluorescence are used to measure velocity and concentration fields, respectively. The measured expected mass fraction functions are observed to be approximately self-similar when concentration values are normalized by the centreline mean concentration. The moments of the expected mass fraction function are observed to be simply related to the centreline moments of the probability density function of scalar concentration. Arguments based on a source fluid, non-source fluid decomposition of the scalar probability density function are used to explain these observations. The results are compared with the theoretical and experimental results established for a line source of scalar in grid turbulence.

Sarathi, Partha; Gurka, Roi; Sullivan, Paul J.; Kopp, Gregory A.

2010-11-01

30

Spreading and Mixing of Soluble Contaminant Plumes in Self-Similar Porous Media. Volume 1. Final Report.  

National Technical Information Service (NTIS)

Contaminant plume spreading and oxygen-limited biodegradation of such plumes were analyzed. Relations among the plume's spreading coefficient (macrodispersivity), its mixing coefficient, and the statistics of self-similar log-conductivity were investigate...

M. W. Kemblowski G. E. Urroz C. M. Chang Y. Ma J. C. Wen

1993-01-01

31

Thruster-plume-induced contamination measurements from the PIC and SPIFEX flight experiments  

NASA Astrophysics Data System (ADS)

This paper documents thruster plume induced contamination measurements from the PIC (Plume Impingement Contamination) and SPIFEX (Shuttle Plume Impingement Flight Experiment) flight experiments. The SPIFEX flight experiment was flown on Space Shuttle mission STS-64 in 1994. Contamination measurements of molecular deposition were made by XPS (X-ray Photo Spectroscopy). Droplet impact features were also recorded with SEM (Scanning Electron Microscope) scans on Kapton and aluminum foil substrates. The PIC flight experiment was conducted during STS-74 in 1996. Quartz Crystal Microbalances (QCMs) measured contaminant deposition from U.S. and Russian thruster firings. Droplet impact observations were made with SEM scans of the Shuttle RMS (Remote Manipulator System) camera lens. These flight experiments were successful in providing measurements of plume induced contamination as well as droplet impact damage. These measurements were the basis of the plume contamination models developed for the International Space Station (ISS).

Soares, Carlos E.; Barsamian, Hagop; Rauer, Scott

2002-09-01

32

Thruster plume induced contamination measurements from the PIC and SPIFEX flight experiments  

NASA Astrophysics Data System (ADS)

This paper documents thruster plume induced contamination measurements from the PIC (Plume Impingement Contamination) and SPIFEX (Shuttle Plume Impingement Flight Experiment) flight experiments. The SPIFEX flight experiment was flown on Space Shuttle mission STS-64 in 1994. Contamination measurements of molecular deposition were made by XPS (X-ray Photo Spectroscopy). Droplet impact features were also recorded with SEM (Scanning Electron Microscope) scans on Kapton and aluminum foil substrates. The PIC flight experiment was conducted during STS-74 in 1996. Quartz Crystal Microbalances (QCMs) measured contaminant deposition from U.S. and Russian thruster firings. Droplet impact observations were made with SEM scans of the Shuttle RMS (Remote Manipulator System) camera lens. These flight experiments were successful in providing measurements of plume induced contamination as well as droplet impact damage. These measurements were the basis of the plume contamination models developed for the International Space Station (ISS).

Soares, Carlos; Barsamian, Hagop; Rauer, Scott

2003-09-01

33

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

SciTech Connect

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

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

1998-09-01

34

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

EPA Science Inventory

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

35

Interactive visual framework to demonstrate the uncertainty of contaminated plume investigation  

Microsoft Academic Search

This program is developed under the numerical modeling software GeoSys\\/Rockflow to demonstrate the uncertainty of the contaminated plume investigation based on our visual framework. Here wells will be created ,and interpolated by using special interpolation method with the interface with an interpolation software Surfer to generate the contaminated plume. Wells could also be deleted and added for a new sampling.

Cui Chen; Christof Beyer; Sebastian Bauer; Olaf Kolditz

36

Field demonstration of technologies for delineating uranium contaminated soils  

SciTech Connect

An Integrated Demonstration Program, hosted by the Fernald Environmental Restoration Management Corporation (FERMCO), has been established for investigating technologies applicable to the characterization and remediation of soils contaminated with uranium. An important part of this effort is the evaluation of field screening tools capable of acquiring high resolution information on the distribution of uranium contamination in surface soils in a cost-and-time efficient manner. Consistent with this need, four field screening technologies have been demonstrated at two hazardous waste sites at the FERMCO. The four technologies tested are wide-area gamma spectroscopy, beta scintillation counting, laser ablation-inductively coupled plasma-atomic emission spectroscopy (LA-ICP-AES), and long-range alpha detection (LRAD). One of the important findings of this demonstration was just how difficult it is to compare data collected by means of multiple independent measurement techniques. Difficulties are attributed to differences in measurement scale, differences in the basic physics upon which the various measurement schemes are predicated, and differences in the general performance of detector instrumentation. It follows that optimal deployment of these techniques requires the development of an approach for accounting for the intrinsic differences noted above. As such, emphasis is given in this paper to the development of a methodology for integrating these techniques for use in site characterization programs as well as the development of a framework for interpreting the collected data. The methodology described here also has general application to other field-based screening technologies and soil sampling programs.

Tidwell, V.C. [Sandia National Labs., Albuquerque, NM (United States); Cunnane, J.C. [Argonne National Lab., IL (United States); Schwing, J. [Fernald Environmental Restoration Management Co., Springdale, OH (United States); Lee, S.Y. [Oak Ridge National Lab., TN (United States); Perry, D.L. [Lawrence Berkeley Lab., CA (United States); Morris, D.E. [Los Alamos National Lab., NM (United States)

1993-11-01

37

Subsurface biobarrier formation by microorganism injection for contaminant plume control.  

PubMed

The concept of an in situ mixture of residual soil and aerobic microorganisms as a biobarrier for controlling contaminant plume was evaluated in this study. Azotobacter chroococcum was inoculated into soil with oxygen as the electron acceptor and appropriate substrate to induce biofilm clog soil pores. The hydraulic conductivity of soil decreased by 1/8000 while substrate and oxygen were provided to the injected microorganism, and increased by 400% when no substrate was provided. A series of column experiments were carried out to measure the hydraulic conductivity of soil specimens. The results showed that the highest hydraulic conductivity reduction occurred when the substrate and electron acceptors were first introduced, and this reduction increased toward the outlet of the column. The substrate was consumed mostly at the inlet and was distributed with time. The analysis of volatile substances after the test showed that the inlet had a high organic content and the outlet had a low organic content. PMID:16569610

Kim, Geonha; Lee, Seungbong; Kim, Younguk

2006-02-01

38

Delineation of Groundwater and Soil Contamination Using EM Survey at an Industrial Abandoned Site  

Microsoft Academic Search

It is important to evaluate and monitor the environmental impacts by the activity in our hand with appropriate methods, and the geophysical techniques have often been using in the subsurface environmental monitoring and remediation processes. In the study an Electromagnetic survey (EM) is performed to delineate deeply the extent of contamination at an industrial abandoned site, to detect the spread

Zhang Shaohong

2010-01-01

39

Characterization of redox conditions in groundwater contaminant plumes  

Microsoft Academic Search

Evaluation of redox conditions in groundwater pollution plumes is often a prerequisite for understanding the behaviour of the pollutants in the plume and for selecting remediation approaches. Measuring of redox conditions in pollution plumes is, however, a fairly recent issue and yet relative few cases have been reported. No standardised or generally accepted approach exists. Slow electrode kinetics and the

Thomas H Christensen; Poul L Bjerg; Steven A Banwart; Rasmus Jakobsen; Gorm Heron; Hans-Jørgen Albrechtsen

2000-01-01

40

Model Intercomparison Study to Investigate a Dense Contaminant Plume in a Complex Hydrogeologic System  

SciTech Connect

A joint Russian and U.S. model intercomparison study was undertaken for developing more realistic contaminant transport models of the Mayak Site, Southern Urals. The test problems were developed by the Russian Team based on their experience modeling contaminant migration near Lake Karachai. The intercomparison problems were designed to address lake and contaminant plume interactions, as well as river interactions and plume density effects. Different numerical codes were used. Overall there is good agreement between the results of both models. Features shown by both models include (1) the sinking of the plume below the lake, (2) the raising of the water table in the fresh water adjacent to the lake in response to the increased pressure from the dense plume, and (3) the formation of a second sinking plume in an area where evapotranspiration exceeded infiltration, thus increasing the solute concentrations above the source (i.e., lake) values.

Williams, Mark D. (BATTELLE (PACIFIC NW LAB)); Cole, Charles R. (BATTELLE (PACIFIC NW LAB)); Foley, Michael G. (BATTELLE (PACIFIC NW LAB)); Zinina, Galina A. (Institute of Physics and Power Engineering); Zinin, Alexander I. (Institute of Physics and Power Engineering); Vasil'Kova, Nelly A. (State Geological Enterprise); Samsonova, Lilia M. (VISITORS)

2001-12-01

41

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...

42

Contaminant plume monitoring adjacent to the Kesterson Reservoir, California  

SciTech Connect

Detailed ground conductivity surveys have been made twice with the Geonics EM31 and EM34 systems over a 2 km{sup 2} area adjacent to Ponds 1, 2 and 5 of the Kesterson Reservoir. In spite of relatively high and variable near-surface conductivities, the first survey in October 1987 indicated that the saline agricultural groundwater discharge into Kesterson Reservoir between 1981 and 1986 had migrated a maximum lateral distance of about 300 m from Pond 2, the most intensively used storage pond. To determine the extent to which the contaminant plume was changing as a consequence of pond flooding with less saline, native groundwater starting in 1986, we conducted a second survey in October 1988, almost exactly one year after the first survey. Reanalysis of the 1987 data was done in conjunction with analysis of the 1988 data. Comparisons of the two data sets indicate that the shallowest soils and sediments, those within the first 2 to 3 meters of the surface, are less conductive in 1988. As supported by water level data in a number of observation wells along the edge of the survey area, and further confirmed by numerical modeling, the lower ground conductivities near the surface are due to a deeper water table and reduction in average water saturation in the unsaturated zone. 18 refs., 26 figs.

Goldstein, N.E.; Pillsbury, S.L.; Daggett, J.S.; Benson, S.M. (Lawrence Berkeley Lab., CA (USA))

1989-06-01

43

Comparison of three nonparametric kriging methods for delineating heavy-metal contaminated soils  

SciTech Connect

The probability of pollutant concentrations greater than a cutoff value is useful for delineating hazardous areas in contaminated soils. It is essential for risk assessment and reclamation. In this study, three nonparametric kriging methods [indicator kriging, probability kriging, and kriging with the cumulative distribution function (CDF) of order statistics (CDF kriging)] were used to estimate the probability of heavy-metal concentrations lower than a cutoff value. In terms of methodology, the probability kriging estimator and CDF kriging estimator take into account the information of the order relation, which is not considered in indicator kriging. Since probability kriging has been shown to be better than indicator kriging for delineating contaminated soils, the performance of CDF kriging, which the authors propose, was compared with that of probability kriging in this study. A data set of soil Cd and Pb concentrations obtained from a 10-ha heavy-metal contaminated site in Taoyuan, Taiwan, was used. The results demonstrated that the probability kriging and CDF kriging estimations were more accurate than the indicator kriging estimation. On the other hand, because the probability kriging was based on the cokriging estimator, some unreliable estimates occurred in the probability kriging estimation. This indicated that probability kriging was not as robust as CDF kriging. Therefore, CDF kriging is more suitable than probability kriging for estimating the probability of heavy-metal concentrations lower than a cutoff value.

Juang, K.W.; Lee, D.Y

2000-02-01

44

Assessing Redox Potential and Fluid Conductivity of a Contaminant Plume from Geoelectric Methods  

Microsoft Academic Search

The redox potential and the fluid conductivity of a contaminant plume are two key-parameter to evaluate the plume development and to propose appropriate remediation technologies. we applied geo-electrical methods (self-potential, SP, and electrical resistivity tomography, ERT) to the Entressen landfill site (South-eastern France). From the knowledge of the piezometric head variation of the groundwater, the electrokinetic source is removed from

V. Naudet; A. Revil; E. Rizzo; J. Bottero; P. Begassat

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

Kriging with cumulative distribution function of order statistics for delineation of heavy-metal contaminated soils  

SciTech Connect

Accurate delineation of contaminated soils is essential for risk assessment and remediation. The probability of pollutant concentrations lower than a cutoff value is more important than the best estimate of pollutant concentrations for unsampled locations in delineating contaminated soils. In this study, a new method, kriging with the cumulative distribution function (CDF) of order statistics (CDF kriging), is introduced and compared with indicator kriging. It is used to predict the probability that extractable concentrations of Zn will be less than a cut-off value for soils to be declared hazardous. The 0.1 M HCl-extractable Zn concentrations of topsoil of a paddy field having an area of about 2000 ha located in Taiwan are used. A comparison of the CDF of order statistics and indicator function transformation shows that the variance and the coefficient of variation (CV) of the CDF of order statistics transformed data are smaller than those of the indicator function transformed data. This suggests that the CDF of order statistics transformation possesses less variability than does the indicator function transformation. In addition, based on cross-validation, CDF kriging is found to reduce the mean squared errors of estimations by about 30% and to reduce the mean kriging variances by about 26% compared with indicator kriging.

Juang, K.W.; Lee, D.Y.; Hsiao, C.K. [National Taiwan Univ., Tapei (Taiwan, Province of China)

1998-10-01

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

Simultaneous optimization of dense non-aqueous phase liquid (DNAPL) source and contaminant plume remediation.  

PubMed

A framework is developed for simultaneous, optimal design of groundwater contaminant source removal and plume remediation strategies. The framework allows for varying degrees of effort and cost to be dedicated to source removal versus plume remediation. We have accounted for the presence of physical heterogeneity in the DNAPL source, since source heterogeneity controls mass release into the plume and the efficiency of source removal efforts. We considered high and low estimates of capital and operating costs for chemical flushing removal of the source, since these are expected to vary form site to site. Using the lower chemical flushing cost estimates, it is found that the optimal allocation of funds to source removal or plume remediation is sensitive to the degree of heterogeneity in the source. When the time elapsed between the source release and the implementation of remediation was varied, it was found that, except for the longest elapsed time (50,000 days), a combination of partial source removal and plume remediation was most efficient. When first-order, dissolved contaminant degradation was allowed, source removal was found to be unnecessary for the cases where the degradation rate exceeded intermediate values of the first-order rate constant. Finally, it was found that source removal became more necessary as the degree of aquifer heterogeneity increased. PMID:17257707

Mayer, Alex; Endres, Karen L

2007-01-25

49

A multilayer groundwater sampler for characterizing contaminant plumes  

SciTech Connect

This final report describes activities related to the design and initial demonstration of a passive multilayer groundwater sampling system. The apparatus consists of remotely controlled cylinders filled with deionized water which are connected in tandem. Vertical fine structure of contaminants are easily defined. Using the apparatus in several wells may lead to three dimensional depictions of groundwater contamination, thereby providing the information necessary for site characterization and remediation.

Kaplan, E.; Heiser, J.

1992-12-18

50

A multilayer groundwater sampler for characterizing contaminant plumes. Final report  

SciTech Connect

This final report describes activities related to the design and initial demonstration of a passive multilayer groundwater sampling system. The apparatus consists of remotely controlled cylinders filled with deionized water which are connected in tandem. Vertical fine structure of contaminants are easily defined. Using the apparatus in several wells may lead to three dimensional depictions of groundwater contamination, thereby providing the information necessary for site characterization and remediation.

Kaplan, E.; Heiser, J.

1992-12-18

51

Testing of stack-unit/aquifer sensitivity analysis using contaminant plume distribution in the subsurface of Savannah River Site, South Carolina, USA  

USGS Publications Warehouse

Published information on the correlation and field-testing of the technique of stack-unit/aquifer sensitivity mapping with documented subsurface contaminant plumes is rare. The inherent characteristic of stack-unit mapping, which makes it a superior technique to other analyses that amalgamate data, is the ability to deconstruct the sensitivity analysis on a unit-by-unit basis. An aquifer sensitivity map, delineating the relative sensitivity of the Crouch Branch aquifer of the Administrative/Manufacturing Area (A/M) at the Savannah River Site (SRS) in South Carolina, USA, incorporates six hydrostratigraphic units, surface soil units, and relevant hydrologic data. When this sensitivity map is compared with the distribution of the contaminant tetrachloroethylene (PCE), PCE is present within the Crouch Branch aquifer within an area classified as highly sensitive, even though the PCE was primarily released on the ground surface within areas classified with low aquifer sensitivity. This phenomenon is explained through analysis of the aquifer sensitivity map, the groundwater potentiometric surface maps, and the plume distributions within the area on a unit-by- unit basis. The results of this correlation show how the paths of the PCE plume are influenced by both the geology and the groundwater flow. ?? Springer-Verlag 2006.

Rine, J. M.; Shafer, J. M.; Covington, E.; Berg, R. C.

2006-01-01

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

Analysis of the remediation systems on the contaminant plume at the Plainville landfill  

SciTech Connect

The Plainville landfill, located in Plainville, Massachusetts, has been the subject of study by several groups in recent years. A contaminant plume, exiting from the southwest corner of the landfill, is contaminating the groundwater downgradient and may affect drinking water wells located there. A two-phase remediation scheme, consisting of an interim overburden air sparging system and a final proposed pump and treat and air sparging system, has been proposed to mitigate the groundwater contaminant plume. This thesis assesses these remediation systems to determine their ability to remediate the contaminants in the groundwater plume. The interim and final proposed air sparging systems were analyzed using existing quarterly reports and a literature review. A MODFLOW groundwater flow model was used to analyze the pump and treat system. These analyses were then compared to the model utilized to design the remediation scheme. Several discrepancies in the design of the remediation scheme were noted as a result of this analysis. First, the presence of till lenses throughout the remediation zone was not addressed. Also, the extraction of water from the competent bedrock layer appears counterproductive. In addition, the air sparging system was not field tested to ascertain the flow pattern in the subsurface. Finally, the installation of the bedrock air sparging wells appears redundant. These discrepancies, however, will only decrease the projected efficiency of the proposed remediation schemes and increase clean up time. Consequently, the results of this study seem to indicate that the proposed remediation scheme is adequately designed.

Woodworth, R.L.

1999-06-01

54

Effects of hydrogeological characteristics on the attenuation of TCE- contaminated groundwater plume in Wonju, Korea  

NASA Astrophysics Data System (ADS)

Key attributes to temporal and seasonal variation of TCE and its daughter products at an industrial complex, Wonju, Korea were evaluated using groundwater monitoring data along with data from field investigations. The purpose of this study is to analyze the hydrogeological characteristics and seasonal variations associated with the plume attenuation of TCE and its daughter products. Study site is underlain by Jurassic biotite granite which is covered by quarternary alluvium. Average hydraulic conductivities of alluvial layer and bed rock are 2.4*10-3 and 2.0*10-4 cm/sec, respectively. The alluvial layer acts as a main layer for TCE contaminated groundwater flow. Average annual rainfall in this study area is 1,414 mm/year and over 65% of annual precipitation is concentrated in July, August and September. Seasonal variation of TCE contaminant plume shape near the source area and downgradient area are different depending on the surface recharge characteristics. The downgradient area is not much affected by seasonal rainfalls, but TCE contaminant concentration in the source area is greatly affected by the seasonal rainfalls. The water table fluctuation at the source area was maximally 1.95 m but the downgradient at industrial complex area was 0.9 m during concentrated rainfall events. General tendency of TCE contaminant concentrations at source zone was highly fluctuated and temporally increased due to rainfall events. As a result, due to the limited recharge and time-lag of the impact of precipitation in summer season, the TCE contaminant plume distribution and the impact of seasonal effect diminish as the distance from the source area increases. Keywords : TCE, recharge, precipitation, plume attenuation, seasonal variation

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

2010-12-01

55

Coupled CFD-DSMC Simulations for Contamination Evaluation on Envisat Due to OCM Thruster Plumes  

NASA Astrophysics Data System (ADS)

During October 2010, the European ENVISAT satellite conducted a successful Orbit Change Manoeuvre (OCM) to lower its orbital altitude by 17 km. Prior to this OCM, an analysis was carried out to assess whether the resulting thruster plume would contaminate subsystems of the satellite including optical equipment and solar panels. This involved using Computational Fluid Dynamics (CFD) and a chemical equilibrium code to evaluate the thruster nozzle exit conditions followed by a Direct Simulation Monte Carlo (DSMC) simulation of the plume flowfield. The resulting data were evaluated in conjunction with measurements of incoming UV signal to the SCIAMACHY instrument to give a likely contamination level due to the upcoming OCM. The calculations showed that the only possible contamination issue would be on the mirrors of the Limb and Nadir port of the SCIAMACHY instrument and so the analysis and quantification of contamination focused on this. Supplemental data from UV measurements from SCIAMACHY reduced the uncertainty to the point where the contamination level could be roughly quantified and regarded as not critical. This was verified after the OCM using further UV measurements.

Passaro, A.; Murray, N.; Snel, R.; Krieg, E.

2011-08-01

56

Origin of a mixed brominated ethene groundwater plume: contaminant degradation pathways and reactions.  

PubMed

On the basis of a combination of laboratory microcosm experiments, column sorption experiments, and the current spatial distribution of groundwater concentrations, the origin of a mixed brominated ethene groundwater plume and its degradation pathway were hypothesized. The contaminant groundwater plume was detected downgradient of a former mineral processing facility, and consisted of tribromoethene (TriBE), cis-1,2-dibromoethene (c-DBE), trans-1,2-dibromoethene (t-DBE), and vinyl bromide (VB). The combined laboratory and field data provided strong evidence that the origin of the mixed brominated ethene plume was a result of dissolution of the dense non-aqueous-phase liquid 1,1,2,2-tetrabromoethane (TBA) atthe presumed source zone, which degraded rapidly (half-life of 0.2 days) to form TriBE in near stoichiometric amounts. TriBE then degraded (half-life of 96 days) to form c-DBE, t-DBE, and VB via a reductive debromination degradation pathway. Slow degradation of c-DBE (half-life >220 days), t-DBE (half-life 220 days), and VB (half-life >220 days) coupled with their low retardation coefficients (1.2, 1.2, and 1.0 respectively) resulted in the formation of an extensive mixed brominated ethene contaminant plume. Without this clearer understanding of the mechanism for TBA degradation, the origin of the mixed brominated ethene groundwater contamination could have been misinterpreted, and inappropriate and ineffective source zone and groundwater remediation techniques could be applied. PMID:17593741

Patterson, Bradley M; Cohen, Elizabeth; Prommer, Henning; Thomas, David G; Rhodes, Stuart; McKinley, Allan J

2007-02-15

57

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

PubMed

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

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

2012-10-11

58

Cost-effective sampling network design for contaminant plume monitoring under general hydrogeological conditions.  

PubMed

A new simulation-optimization methodology is developed for cost-effective sampling network design associated with long-term monitoring of large-scale contaminant plumes. The new methodology is similar in concept to the one presented by Reed et al. (Reed, P.M., Minsker, B.S., Valocchi, A.J., 2000a. Cost-effective long-term groundwater monitoring design using a genetic algorithm and global mass interpolation. Water Resour. Res. 36 (12), 3731-3741) in that an optimization model based on a genetic algorithm is coupled with a flow and transport simulator and a global mass estimator to search for optimal sampling strategies. However, this study introduces the first and second moments of a three-dimensional contaminant plume as new constraints in the optimization formulation, and demonstrates the proposed methodology through a real-world application. The new moment constraints significantly increase the accuracy of the plume interpolated from the sampled data relative to the plume simulated by the transport model. The plume interpolation approaches employed in this study are ordinary kriging (OK) and inverse distance weighting (IDW). The proposed methodology is applied to the monitoring of plume evolution during a pump-and-treat operation at a large field site. It is shown that potential cost savings up to 65.6% may be achieved without any significant loss of accuracy in mass and moment estimations. The IDW-based interpolation method is computationally more efficient than the OK-based method and results in more potential cost savings. However, the OK-based method leads to more accurate mass and moment estimations. A comparison of the sampling designs obtained with and without the moment constraints points to their importance in ensuring a robust long-term monitoring design that is both cost-effective and accurate in mass and moment estimations. Additional analysis demonstrates the sensitivity of the optimal sampling design to the various coefficients included in the objective function of the optimization model. PMID:15722172

Wu, Jianfeng; Zheng, Chunmiao; Chien, Calvin C

2005-01-20

59

ASSESSMENT OF PLUME DIVING  

EPA Science Inventory

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

60

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

61

3-D spectral IP imaging: Non-invasive characterization of contaminant plumes. 1998 annual progress report  

SciTech Connect

'The overall objective of this project is to develop the scientific basis for characterizing contaminant plumes in the earth''s subsurface using field measurements of induced polarization (IP) effects. Three specific objectives towards this end are: (1) understanding IP at the laboratory level through measurements of complex resistivity as a function of frequency in rock and soil samples with varying pore geometries, pore fluid conductivities and saturations, and contaminant chemistries and concentrations; (2) developing effective data acquisition techniques for measuring the critical IP responses (time domain or frequency domain) in the field; (3) developing modeling and inversion algorithms that permit the interpretation of field IP data in terms of subsurface geology and contaminant plume properties. The authors laboratory experiments to date are described in Appendices A and B, which consist of two papers submitted to the annual SAGEEP conference (Frye et al., 1998; Sturrock et al., 1998). The experiments involved measurements of complex resistivity vs. frequency on a suite of brine saturated sandstone samples. In one set of experiments, the fluid chemistry (pH, ionic strength, and cation type) was varied. In a second set of experiments, the microgeometry of the rock matrix was varied. The experiments showed that spectral IP responses are sensitive to subtle variations in both the solution chemistry and rock microgeometry. The results demonstrate that spectral IP responses have the potential of being sensitive indicators of in-situ chemistry and microgeometry, the latter of which may be related to the hydraulic properties. Data Acquisition The authors have been looking in some detail at the effects of electromagnetic coupling and how to practically deal with it. In this area, the results to date are summarized in Vandiver (1998). The progress in the development of modeling and inversion algorithms for IP is described in Appendix C, a paper submitted to the annual SAGEEP conference (Shi et al., 1998). The authors have developed algorithms for forward modeling and inversion of spectral IP data in 3-D media. The algorithms accommodate a general earth model with a complex electrical conductivity as a function of frequency and 3-D spatial position. Using regularization and optimization techniques, the inversion algorithm obtains a 3-D image of resistivity amplitude and phase for each frequency contained in the data set. They have begun testing their algorithms on synthetic data generated from a simple model of a contaminant plume. The complex resistivity parameters of the background medium and plume are based on the laboratory results described above.'

Morgan, F.D.; Rodi, W. [Massachusetts Inst. of Tech., Cambridge, MA (US); Lesmes, D. [Boston Coll., Chestnut Hill, MA (US)

1998-06-01

62

Integration of Predicted Atmospheric Contaminant Plumes into ArcView GIS  

SciTech Connect

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

Koffman, Larry D.

2005-10-10

63

COLLABORTIVE RESEARCH: Lagrangian studies of the transport, transformation, and biological impact of nutrients and contaminant metals in a buoyant plume: A process study in an operational ocean observatory  

Microsoft Academic Search

We propose a coordinated program of field and numerical experiments to examine processes that control the fate and transport of nutrients and chemical contaminants in the Hudson River plume, a plume that emanates from one of the nation's most urban estuaries -- the New York\\/New Jersey Harbor complex. Urban estuarine plumes represent a major pathway for the transport of nutrients

Robert Chant; John Reinfelder; Scott Glenn; Oscar Schofield; John Wilkin; Robert Houghton; Bob Chen; Meng Zhou; Paul Bissett; Mark Moline; Tom Frazer

64

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

65

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

66

Free-product plume distribution and recovery modeling prediction in a diesel-contaminated volcanic aquifer  

NASA Astrophysics Data System (ADS)

Light non-aqueous phase liquids (LNAPL) represent one of the most serious problems in aquifers contaminated with petroleum hydrocarbons liquids. To design an appropriate remediation strategy it is essential to understand the behavior of the plume. The aim of this paper is threefold: (1) to characterize the fluid distribution of an LNAPL plume detected in a volcanic low-conductivity aquifer (˜0.4 m/day from slug tests interpretation), (2) to simulate the recovery processes of the free-product contamination and (3) to evaluate the primary recovery efficiency of the following alternatives: skimming, dual-phase extraction, Bioslurping and multi-phase extraction wells. The API/Charbeneau analytical model was used to investigate the recovery feasibility based on the geological properties and hydrogeological conditions with a multi-phase (water, air, LNAPL) transport approach in the vadose zone. The modeling performed in this research, in terms of LNAPL distribution in the subsurface, show that oil saturation is 7% in the air-oil interface, with a maximum value of 70% in the capillary fringe. Equilibrium between water and LNAPL phases is reached at a depth of 1.80 m from the air-oil interface. On the other hand, the LNAPL recovery model results suggest a remarkable enhancement of the free-product recovery when simultaneous extra-phase extraction was simulated from wells, in addition to the LNAPL lens. Recovery efficiencies were 27%, 65%, 66% and 67% for skimming, dual-phase extraction, Bioslurping and multi-phase extraction, respectively. During a 3-year simulation, skimmer wells and multi-phase extraction showed the lowest and highest LNAPL recovery rates, with expected values from 207 to 163 and 2305 to 707 l-LNAPL/day, respectively. At a field level we are proposing a well distribution arrangement that alternates pairs of dual-phase well-Bioslurping well. This not only improves the recovery of the free-product plume, but also pumps the dissolve plume and enhances in situ biodegradation in the vadose zone. Thus, aquifer and soil remediation can be achieved at a shorter time. Rough calculations suggest that LNAPL can be recovered at an approximate cost of $6-$10/l.

Hernández-Espriú, Antonio; Martínez-Santos, Pedro; Sánchez-León, Emilio; Marín, Luis E.

67

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.  

National Technical Information Service (NTIS)

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 worki...

R. H. Ketelle R. R. Lee

1992-01-01

68

Simulation of the effect of remediation on EDB and 1,2-DCA plumes at sites contaminated by leaded gasoline.  

PubMed

An analytical model is used to simulate the effects of partial source removal and plume remediation on ethylene dibromide (EDB) and 1,2-dichloroethane (1,2-DCA) plumes at contaminated underground storage tank (UST) sites. The risk posed by EDB, 1,2-DCA, and commingled gasoline hydrocarbons varies throughout the plume over time. Dissolution from the light nonaqueous phase liquid (LNAPL) determines the concentration of each contaminant near the source, but biological decay in the plume has a greater influence as distance downgradient from the source increases. For this reason, compounds that exceed regulatory standards near the source may not in downgradient plume zones. At UST sites, partial removal of a residual LNAPL source mass may serve as a stand alone remedial technique if dissolved concentrations in the source zone are within several orders of magnitude of the applicable government or remedial standards. This may be the case with 1,2-DCA; however, EDB is likely to be found at concentrations that are orders of magnitude higher than its low Maximum Contaminant Level (MCL) of 0.05 microg/L (micrograms per liter). For sites with significant EDB contamination, even when plume remediation is combined with source depletion, significant timeframes may be required to mitigate the impact of this compound. Benzene and MTBE are commonly the focus of remedial efforts at UST sites, but simulations presented here suggest that EDB, and to a lesser extent 1,2-DCA, could be the critical contaminants to consider in the remediation design process at many sites. PMID:19535166

Henderson, James K; Falta, Ronald W; Freedman, David L

2009-05-13

69

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

70

Phytoforensics, dendrochemistry, and phytoscreening: New green tools for delineating contaminants from past and present  

USGS Publications Warehouse

As plants evolved to be extremely proficient in mass transfer with their surroundings and survive as earth's dominant biomass, they also accumulate and store some contaminants from surroundings, acting as passive samplers. Novel applications and analytical methods have been utilized to gain information about a wide range of contaminants in the biosphere soil, water, and air, with information available on both past (dendrochemistry) and present (phytoscreening). Collectively these sampling approaches provide rapid, cheap, ecologically friendly, and overall "green" tools termed "Phytoforensics". ?? 2011 American Chemical Society.

Burken, J. G.; Vroblesky, D. A.; Balouet, J. C.

2011-01-01

71

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

2007-04-27

72

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

73

Comparison of field-observed and model-predicted plume trends at fuel-contaminated sites: implications for natural attenuation rates.  

PubMed

Subsequent to modeling of natural attenuation processes to predict contaminant trends and plume dynamics, monitoring data were used to evaluate the effectiveness of natural attenuation at reducing contaminant concentrations in groundwater at seven fuel-contaminated sites. Predicted and observed contaminant trends at seven sites were compared in order to empirically assess the accuracy of some fundamental model input parameters and assumptions. Most of the models developed for the study sites tended to overestimate plume migration distance, source persistence, and/or the time required for the benzene, toluene, ethyl benzene, and xylenes (BTEX) plumes to attenuate. Discrepancies between observed and predicted contaminant trends and plume behavior suggested that the influence of natural attenuation process may not have been accurately simulated. The conservatism of model simulations may be attributed to underestimation of natural source weathering rates, overestimation of the mass of contaminant present in the source area, and/or use of overly conservative first-order solute decay rates. PMID:16252060

Jeong, Seung-Woo; Kampbell, Donald H; An, Youn-Joo; Henry, Bruce M

2005-08-17

74

Combining pump-and-treat and physical barriers for contaminant plume control.  

PubMed

A detailed analysis is presented of the hydraulic efficiency of plume management alternatives that combine a conventional pump-and-treat system with vertical, physical hydraulic barriers such as slurry walls or sheet piles. Various design settings are examined for their potential to reduce the pumping rate needed to obtain a complete capture of a given contaminated area. Using established modeling techniques for flow and transport, those barrier configurations (specified by location, shape, and length) that yield a maximum reduction of the pumping rate are identified assuming homogeneous aquifer conditions. Selected configurations are further analyzed concerning their hydraulic performance under heterogeneous aquifer conditions by means of a stochastic approach (Monte Carlo simulations) with aquifer transmissivity as a random space function. The results show that physical barriers are an appropriate means to decrease expected (mean) pumping rates, as well as the variance of the corresponding pumping rate distribution at any given degree of heterogeneity. The methodology presented can be transferred easily to other aquifer scenarios, provided some basic premises are fulfilled, and may serve as a basis for reducing the pumping rate in existing pump-and-treat systems. PMID:15584299

Bayer, Peter; Finkel, Michael; Teutsch, Georg

75

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

2012-10-04

76

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

NASA Astrophysics Data System (ADS)

The stable carbon isotope composition of chlorinated aliphatic compounds such as chlorinated methanes, ethanes and ethenes was examined as an intrinsic fingerprint for apportionment of sources. A complex field site located in Ferrara (Italy), with more than 50 years history of use of chlorinated aliphatic compounds, was investigated in order to assess contamination sources. Several contamination plumes were found in a complex alluvial sandy multi-aquifer system close to the river Po; sources are represented by uncontained former industrial and municipal dump sites as well as by spills at industrial areas.

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

2013-10-01

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

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

PubMed

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

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

2013-07-16

79

Assessing the impact of source-zone remediation efforts at the contaminant-plume scale through analysis of contaminant mass discharge.  

PubMed

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 7kg/d, and then declined to approximately 2kg/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 0.2kg/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. PMID:22115080

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

2011-08-26

80

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

81

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

82

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

83

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

84

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

85

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

Microsoft Academic Search

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

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

2008-01-01

86

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

87

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

2005-10-26

88

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

89

Using Airborne and Ground Electromagnetic Surveys and DC Resistivity Surveys to Delineate a Plume of Conductive Water at an In-Channel Coalbed Methane Produced Water Impoundment Near the Powder River, Wyoming  

NASA Astrophysics Data System (ADS)

Development of coal bed methane (CBM) in the Powder River Basin of Wyoming and Montana has significantly increased since 1997. Production of CBM involves withdrawing groundwater from the coal bed to lower the hydrostatic pressure thereby allowing methane to desorb from the coal. The water co-produced with CBM is managed by storing it in impoundments until it can infiltrate to the groundwater, be used for beneficial purposes, or be discharged to surface streams. Skewed Reservoir was constructed as a research site to evaluate disposal of CBM water through infiltration ponds constructed by damming ephemeral streams. Geochemical data collected from monitoring wells placed downgradient of the reservoir detected a plume of water with total dissolved solids concentrations an order of magnitude higher than the CBM water stored in the impoundment. Infiltrating CBM water is suspected to have dissolved salts that were present in the unconsolidated materials beneath the reservoir. A geophysical investigation of the Skewed Reservoir area was conducted in July of 2004 to map the horizontal and vertical extent of the plume and to possibly identify the source of solutes to the infiltrating water. The Department of Energy's National Energy Technology Laboratory contracted Fugro Airborne Surveys to fly their RESOLVE frequency domain airborne electromagnetic (AEM) system with 50-m line spacing at the site. A ground investigation was completed at the same time as the airborne survey. Five 2-D dipole-dipole resistivity surveys and one 3-D pole-dipole survey were conducted using the AGI SuperSting R8/IP multi-channel resistivity imaging system. Additionally, ground conductivity measurements were recorded along each resistivity line using a Geophex GEM-2 multi-frequency ground conductivity meter. All geoelectrical measurements were inverted to obtain the subsurface conductivity distribution. Inversions were constrained using results of downhole borehole induction logs. Results were compared to geological and geochemical data collected from on-site monitoring wells. The geophysical methods accurately delineated the CBM water plume. Differences in the inversion results were observed and are discussed. The AEM data may also prove useful in identifying potential problem areas for locating future in-channel storage impoundments.

Lipinski, B. A.; Harbert, W.; Hammack, R.; Sams, J.; Veloski, G.; Smith, B. D.

2004-12-01

90

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

PubMed Central

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

Evrard, Olivier; Chartin, Caroline; Onda, Yuichi; Patin, Jeremy; Lepage, Hugo; Lefevre, Irene; Ayrault, Sophie; Ottle, Catherine; Bonte, Philippe

2013-01-01

91

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

PubMed

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

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

2013-10-29

92

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

93

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

SciTech Connect

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

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

2005-09-01

94

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...

95

Evaluation of the Ground-Water Contaminant Plume Extending from the 183-H Solar Evaporation Basins.  

National Technical Information Service (NTIS)

The 183-H Solar Evaporation Basins, located on the Hanford Site in southeastern Washington State, were used for solar concentration and storage of process wastes that consisted of nitric, sulfuric, and hydrofluoric acids, contaminated by heavy metals and ...

S. H. Hall

1989-01-01

96

Numerical assessment of plume heat and mechanical loads and contamination on multi-layer insulation in hard vacuum  

Microsoft Academic Search

The paper presents a numerical analysis of plume exhausted from the 10N bipropellant thruster. The computations have been performed for steady state and pulse mode firing of the thruster. The plume impinges a multi-layer insulation (MLI) that covers a satellite surface, where plume effects have been computed for ideal and bulged shapes of the MLI. The ideal shape is a

Gennady Markelov; Rolf Brand; Georg Ibler; Wolfgang Supper

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

Performance analysis of statistical spatial measures for contaminant plume characterization toward risk-based decision making  

NASA Astrophysics Data System (ADS)

The spatial distribution of solute concentration in heterogeneous aquifers is extremely complex and variable over scales ranging from a few millimeters to kilometers. Obtaining a detailed spatial distribution of the concentration field is an elusive goal because of intrinsic technical limitations and budget constraints for site characterization. Therefore, local concentration predictions are highly uncertain and alternative measures of transport must be sought. In this paper, we propose to describe the spatial distribution of the concentrations of a nonreactive tracer plume by means of suitable spatial statistical transport measures, as an alternative to approaches relying only on the ensemble mean concentration. By assuming that the solute concentration is statistically distributed according to the Beta distribution model, we compare several models of concentration moments against numerical simulations and Cape Cod concentration data. These measures provide useful information which are: (i) representative of the overall transport process, (ii) less affected by uncertainty than the local probability density function and (iii) only marginally influenced by local features. The flexibility of the approach is shown by considering three different integral expressions for both the spatial mean and variance of concentration based on previous works. Aiming at a full statistical characterization, we illustrate how the Beta relative cumulative frequency distribution (obtained as a function of the spatial concentration) compares with the numerical cumulative frequencies. Our approach allows to estimate the probability of exceeding a given concentration threshold within the computational or observational domain, which could be used for sampling data campaigns, preliminary risk assessment and model refinement. Finally, our results highlight the importance of goal-oriented model development.

Boso, F.; Barros, F. P. J.; Fiori, A.; Bellin, A.

2013-06-01

99

Intrinsic Anaerobic Bioremediation of Hydrocarbons in Contaminated Subsurface Plumes and Marine Sediments  

NASA Astrophysics Data System (ADS)

In recent years, several classes of petroleum hydrocarbons contaminating subsurface and marine environments have been found susceptible to anaerobic biodegradation using novel mechanisms entirely distinct from aerobic metabolic pathways. For example, the anaerobic decay of toluene can be initiated by the addition of the aryl methyl group to the double bond of fumarate, resulting in a benzylsuccinic acid metabolite. Our work has shown that an analogous mechanism also occurs with ethylbenzene and the xylene isomers, yielding 3-phenyl-1,2-butane dicarboxylic acid and methylbenzylsuccinic acid, respectively. Moreover, these metabolites have been detected in contaminated environments. Most recently, we have identified metabolites resulting from the initial attack of H26- or D26-n-dodecane during degradation by a sulfate-reducing bacterial culture. Using GC-MS, these metabolites were identified as fatty acids that result from C-H or C-D addition across the double bond of fumarate to give dodecylsuccinic acids in which all 26 protons or deuteriums of the parent alkane were retained. Further, when this enrichment culture was challenged with hexane or decane, hexylsuccinic acid or decylsuccinic acid were identified as resulting metabolites. Similarly, the study of an ethylcyclopentane-degrading sulfate-reducing enrichment produced a metabolite, which is consistent with the addition of fumarate to the parent substrate. These novel anaerobic addition products are characterized by similar, distinctive mass spectral (MS) features (ions specific to the succinic acid portion of the molecule) that can potentially be used to probe contaminated environments for evidence of intrinsic remediation of hydrocarbons. Indeed, analyses of water extracts from two gas condensate-contaminated sites resulted in the tentative detection of alkyl- and cycloalkylsuccinic acids ranging from C3 to C9, including ethylcyclopentyl-succinic acid. In water extracts collected from an area underlying a petroleum production plant, MS profiles consistent with the addition products of methylcycloalkenes were observed. This work helps attests to: 1) the extrapolatability of laboratory results to the field, 2) the unifying metabolic features for the anaerobic destruction of diverse types of hydrocarbons, and 3) how this information can be used to assess the intrinsic bioremediation processes in petroleum-contaminated environments.

Nanny, M. A.; Nanny, M. A.; Suflita, J. M.; Suflita, J. M.; Davidova, I.; Kropp, K.; Caldwell, M.; Philp, R.; Gieg, L.; Rios-Hernandez, L. A.

2001-05-01

100

SH-Wave Imaging of Potential Near-Surface Geologic Controls on Contaminant Plume Migration: Fluorspar Area Fault Complex, Western Kentucky USA  

NASA Astrophysics Data System (ADS)

We acquired 18.5 km of near surface SH-wave seismic reflection profiles to evaluate the post-Paleozoic sediment that overlies the southwestern projection of the Fluorspar area fault complex (FAFC) in western Kentucky for neotectonic deformation in the area of an anomalously migrating contaminant plume. Our previous investigations showed that the late-Precambrian-early Paleozoic FAFC has been reactivated and extends above the Paleozoic carbonate bedrock into the approximately 100 meters of low-velocity unlithified Cretaceous, Tertiary, and Quaternary sediment. Newly integrated reflection images indicate deformation from two northeast striking high-angle bedrock fault strands, extending into the lower part of a Pleistocene-Pliocene sand and gravel aquifer, bound and are coincident with the highest concentrations of the TCE-contaminant plume, suggesting the potential for a preferential groundwater flow path. Ongoing shear-wave birefringence experiments will further evaluate the azimuthally anisotropic properties of the sediment at these sites.

Almayahi, A.; Woolery, E.; Hampson, S.

2011-12-01

101

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

102

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

SciTech Connect

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

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

2005-09-01

103

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

104

Analysis of groundwater contamination using concentration-time series recorded during an integral pumping test: bias introduced by strong concentration gradients within the plume.  

PubMed

When only few monitoring wells are available to assess the extent and level of groundwater contamination, inversion of concentration breakthrough curves acquired during an integral pumping test can be used as an alternative quantification method. The idea is to use concentration-time series recorded during integral pumping tests through an inversion technique to estimate contaminant mass fluxes crossing a control plane. In this paper, we examine how a longitudinal concentration gradient along a contaminant plume length scale affects the estimated inversed-concentration distribution and its associated mass flux. The analytically inversed-concentration distribution at the imaginary control plane (ICP) is compared to a numerically generated concentration distribution, treating the latter one as a "real contaminant plume" characterized by the presence of a longitudinal concentration gradient. It is found that the analytically inversed-concentration can lead to overestimation or underestimation of concentration distribution values depending on the transport time period and dispersivity values. At lower dispersivity values, with shorter transport time periods, the analytically inversed-concentration distribution overestimates the "real" concentration distribution. A better fit of the estimated concentration distribution to the "real" one is observed when the transport time period increases, i.e. when the advective front has already crossed the ICP. However, for higher dispersivity values, underestimation of the real concentration distribution is observed. Deviation of the inversed-concentration distribution from the "real" one is assessed for a site-specific concentration gradient term. A concentration gradient adjusted contaminant mass flux is thus formulated to evaluate groundwater contamination levels at a given time period through an ICP. This concentration gradient ratio can indicate whether the ICP is well positioned to evaluate accurately contaminant mass fluxes which are representative of groundwater contamination levels. PMID:16216382

Zeru, Allelign; Schäfer, Gerhard

2005-10-10

105

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

106

Using robust kriging and sequential Gaussian simulation to delineate the copper- and lead-contaminated areas of a rapidly industrialized city in Yangtze River Delta, China  

NASA Astrophysics Data System (ADS)

A total of 540 topsoil samples (0-15 cm), 188 subsoil samples (20-40 cm), and four individual soil profiles were collected in this study for mapping the Cu- and Pb-contaminated areas in soils of Zhangjiagang city, an industrialized city in the Yangtze River Delta region of China. Robust geostatistical methods were applied for identifying possible spatial outliers of Cu and Pb data, and then a sequential Gaussian simulation was employed for delineating the potential areas where Cu or Pb concentration was affected by diffuse pollution. The results showed that the spatial outliers of Cu and Pb were strongly associated with various types of factories. The anthropogenic input of Cu to soils at local hotspots was closely related to emissions of printing and dyeing, metallurgical, and chemical factories, whereas a lead oxide factory and a chemical factory resulted in a considerable increase of Pb in the topsoil of the study area. Approximately 30% of the total land area of the study was at potential risk from the Cu or Pb diffuse pollution resulting from rapid industrialization of the area over the past 20 years.

Zhao, Yongcun; Xu, Xianghua; Huang, Biao; Sun, Weixia; Shao, Xuexin; Shi, Xuezheng; Ruan, Xinling

2007-07-01

107

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

108

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

SciTech Connect

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

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

1997-12-01

109

Vertical Transverse Dispersion Controls the Natural Attenuation of Spatially Variable Plumes  

NASA Astrophysics Data System (ADS)

Many, if not most organic contaminant plumes are spatially variable. This presents a challenge for natural attenuation assessment using traditional methods that rely on monitoring along plume centrelines that are necessarily assumed to be unique. An alternative approach is to characterise the processes that control attenuation, and delineate where those processes occur within the plume. For example, carbon turnover in many organic plumes is constrained to biodegradation at the plume fringe where contaminants mix with electron acceptors. This mixing is influenced by concentration gradients of organics (out of the plume) and oxygen and nitrate (into the plume), and vertical transverse dispersion. Where plumes consist of complex mixtures of organics, an added factor is the preferential degradation of certain compounds (target or non-target organics) due to various microbiological concerns. Accurate prediction of natural attenuation of such plumes may be possible if spatially discrete carbon turnover processes are considered in the context of spatial plume variability. A transect of four highly detailed multilevel sampling wells were installed across a well-studied tar acid plume migrating within the Triassic sandstones in the UK Midlands. The goal of these wells was to locate the upper plume fringe and quantify degradation within those zones. The multilevel sample ports were 20 cm apart to characterise both electron acceptor and donor profiles in great detail. The primary contaminants within the plume are the phenolics (phenol, xylenols, cresols), but other compounds are present that impose a demand on electron acceptor supply (tar neutrals TEX, C4-C8 benzenes, benzofuran and tar bases pyridines, picoline, aniline). The bioactive zone appears to be constrained to a narrow zone less than 1 m thick wherein all dissolved oxygen and nitrate are consumed, with phenol persisting to depth, consistent with weak vertical mixing due to weak dispersion at the scale of diffusion. The vertical position of this fringe varies in space, suggesting that natural attenuation cannot be accurately estimated by extrapolating the reactive processes quantified at one location to the plume as a whole.

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

2003-12-01

110

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

111

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

112

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

PubMed Central

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

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

2011-01-01

113

Biogeochemical and isotopic gradients in a BTEX/PAH contaminant plume: model-based interpretation of a high-resolution field data set.  

PubMed

A high spatial resolution data set documenting carbon and sulfur isotope fractionation at a tar oil-contaminated, sulfate-reducing field site was analyzed with a reactive transport model. Within a comprehensive numerical model, the study links the distinctive observed isotope depth profiles with the degradation of various monoaromatic and polycyclic aromatic hydrocarbon compounds (BTEX/PAHs) under sulfate-reducing conditions. In the numerical model, microbial dynamics were simulated explicitly and isotope fractionation was directly linked to the differential microbial uptake of lighter and heavier carbon isotopes during microbial growth. Measured depth profiles from a multilevel sampling well with high spatial resolution served as key constraints for the parametrization of the model simulations. The results of the numerical simulations illustrate particularly well the evolution of the isotope signature of toluene, which is the most rapidly degrading compound and the most important reductant at the site. The resulting depth profiles at the observation well show distinct differences between the small isotopic enrichment in the contaminant plume core and the much stronger enrichment of up to 3.3 per thousand at the plume fringes. PMID:19924945

Prommer, Henning; Anneser, Bettina; Rolle, Massimo; Einsiedl, Florian; Griebler, Christian

2009-11-01

114

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

SciTech Connect

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

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

1997-12-01

115

Analysis of the Impact of Subsurface Contaminant Plumes on Stream Water Quality Under Natural and Managed Conditions  

NASA Astrophysics Data System (ADS)

The Integrated Hydrology Model (InHM) is a fully-integrated 3D control-volume finite element model which can simulate water flow and solute transport on the two-dimensional land surface and in the three-dimensional dual-continua subsurface under variably-saturated conditions. Full coupling of the surface and subsurface flow regimes is accomplished by simultaneously solving one system of nonlinear discrete equations for overland flow rates and water depths, stream flow rates, subsurface pressure heads, saturations and velocities, as well as water fluxes between continua. The numerical solution of the coupled advection-dispersion equations describing solute transport in the surface and subsurface flow domains is achieved in an analogous manner. High-resolution 3D numerical experiments performed with the model evaluate the downstream surface-water and stream-bottom sediment quality arising from a subsurface solute plume discharging into a stream under natural conditions. These simulations are compared with cases where the plume is intercepted by pumping wells near point of discharge. Comparisons are made for low (baseflow) and high (precipitation-event driven) stream flow rates for each case. A sensitivity analysis involving different surface-subsurface and transport parameters and plume capture scenarios will also be presented.

Keizer, J. P.; Sudicky, E. A.

2001-12-01

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

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

118

Numerical simulations of sulphate emissions from the unsaturated zone on NA processes in ground water - reactive transport modelling of a benzene and naphthalene contaminated plume. Reaktive Transportmodellierungen einer mit Benzen und Naphthalin kontaminierten Abstromfahne  

NASA Astrophysics Data System (ADS)

The supply of electron acceptors from leachate through the unsaturated zone could represent a special boundary condition with regard to contaminant plume spreading in groundwater. This is an important issue for the acceptance of monitored natural attenuation (MNA) strategies and the prediction of NA processes, but which to date has received little attention. The results of the numerical simulations considered herein show problems in parameterisation of the Monod kinetic approach used for modelling biodegradation processes under sulphate reducing conditions and show the effects of different sulphate loads on the future spreading of a benzene and naphthalene plume at a former coking plant. The results indicate a strong influence of sulphate supply and thus highlight the importance of quantifying these electron acceptor sources and loads, and of defining the controlling parameters for predicting long-term trends in plume development.

Hornbruch, G.; Schäfer, D.; Dahmke, A.

2007-06-01

119

Depth-resolved quantification of anaerobic toluene degraders and aquifer microbial community patterns in distinct redox zones of a tar oil contaminant plume.  

PubMed

Microbial degradation is the only sustainable component of natural attenuation in contaminated groundwater environments, yet its controls, especially in anaerobic aquifers, are still poorly understood. Hence, putative spatial correlations between specific populations of key microbial players and the occurrence of respective degradation processes remain to be unraveled. We therefore characterized microbial community distribution across a high-resolution depth profile of a tar oil-impacted aquifer where benzene, toluene, ethylbenzene, and xylene (BTEX) degradation depends mainly on sulfate reduction. We conducted depth-resolved terminal restriction fragment length polymorphism fingerprinting and quantitative PCR of bacterial 16S rRNA and benzylsuccinate synthase genes (bssA) to quantify the distribution of total microbiota and specific anaerobic toluene degraders. We show that a highly specialized degrader community of microbes related to known deltaproteobacterial iron and sulfate reducers (Geobacter and Desulfocapsa spp.), as well as clostridial fermenters (Sedimentibacter spp.), resides within the biogeochemical gradient zone underneath the highly contaminated plume core. This zone, where BTEX compounds and sulfate--an important electron acceptor--meet, also harbors a surprisingly high abundance of the yet-unidentified anaerobic toluene degraders carrying the previously detected F1-cluster bssA genes (C. Winderl, S. Schaefer, and T. Lueders, Environ. Microbiol. 9:1035-1046, 2007). Our data suggest that this biogeochemical gradient zone is a hot spot of anaerobic toluene degradation. These findings show that the distribution of specific aquifer microbiota and degradation processes in contaminated aquifers are tightly coupled, which may be of value for the assessment and prediction of natural attenuation based on intrinsic aquifer microbiota. PMID:18083871

Winderl, Christian; Anneser, Bettina; Griebler, Christian; Meckenstock, Rainer U; Lueders, Tillmann

2007-12-14

120

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

PubMed

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

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

2013-02-16

121

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

Microsoft Academic Search

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

T. Bullen; J. Izbicki

2007-01-01

122

Interpolating and Extrapolating Contaminant Concentrations from Monitor Wells to Model Grids for Fate-and-Transport Calculations  

SciTech Connect

Geostatistical interpolation of groundwater characterization data to visualize contaminant distributions in three dimensions is often hindered by the sparse distribution of samples relative to the size of the plume and scale of heterogeneities. Typically, placement of expensive monitoring wells is guided by the conceptualized plume rather than geostatistical considerations, focusing on contaminated areas rather than thoroughly gridding the plume boundary. The resulting data sets require careful analysis in order to produce plausible plume shells. A purely geostatistical approach is usually impractical; kriging parameters based on the observed data structure can extrapolate contamination far beyond the demonstrated extent of the plume. When more appropriate kriging parameters are selected, holes often occur in the interpolated distribution because realistic kriging ranges may not bridge large gaps between data points. Such artifacts obscure the probable location of the plume boundary and distort the contaminant distribution, obstructing quantitative modeling of remedial strategies. Two methods of constraining kriging can successfully eliminate these geostatistical artifacts. Laterally, the plume boundary may be controlled using a manually constructed mask that delineates the plan-view extent of the plume. After kriging, the mask is used to set all grid cells outside of the plume to a concentration of zero. Use of non-zero control points is a more refined but laborious approach that also bridges data gaps within the body of a plume and permits use of tighter kriging parameters. These can be obtained by manual linear interpolation between measured samples, or derived from historical data migrated along flow paths while accounting for all attenuative processes. Masking and use of non-zero control points result in a plume shell that reflects the intuition and professional judgment of the hydrologist, and can be interpolated automatically to any desired grid, providing initial conditions for fate-and-transport simulations. Error maps are a valuable aid in assessing data density, identifying areas that require additional sampling, or that must be filled by control points, if additional sampling is impractical.

Ward, D. B.; Clement, P.; Bostick, K.

2002-02-26

123

Lazy plumes  

NASA Astrophysics Data System (ADS)

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 constant entrainment coefficient (?) in terms of three dimensionless parameters: the plume radius ?; a parameter ? characterizing the local balance of momentum, buoyancy and volume fluxes; and a parameter ? that characterizes the rate of internal buoyancy flux gain with height. For a plume with a linear internal buoyancy flux gain with height the flow is shown to be a constant-velocity lazy plume. For highly lazy area sources we derive exact solutions for the key plume parameters in terms of ? and an approximate solution for the variation of ? with height. We show that near the source there is a region of zero entrainment.

Hunt, G. R.; Kaye, N. B.

2005-06-01

124

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...

125

Comparative study of methods for WHPA delineation.  

PubMed

Human activities, whether agricultural, industrial, commercial, or domestic, can contribute to ground water quality deterioration. In order to protect the ground water exploited by a production well, it is essential to develop a good knowledge of the flow system and to adequately delineate the area surrounding the well within which potential contamination sources should be managed. Many methods have been developed to delineate such a wellhead protection area (WHPA). The integration of more information on the geologic and hydrogeologic characteristics of the study area increases the precision of any given WHPA delineation method. From a practical point of view, the WHPA delineation methods allowing the simplest and least expensive integration of the available information should be favored. This paper presents a comparative study in which nine different WHPA delineation methods were applied to a well and a spring in an unconfined granular aquifer and to a well in a confined highly fractured rock aquifer. These methods range from simple approaches to complex computer models. Hydrogeological mapping and numerical modeling with MODFLOW-MODPATH were used as reference methods to respectively compare the delineation of the zone of contribution and the zone of travel obtained from the various WHPA methods. Although applied to simple ground water flow systems, these methods provided a relatively wide range of results. To allow a realistic delineation of the WHPA in aquifers of variable geometry, a WHPA delineation method should ensure a water balance and include observed or calculated regional flow characteristics. PMID:17335480

Paradis, Daniel; Martel, Richard; Karanta, Gilbert; Lefebvre, René; Michaud, Yves; Therrien, René; Nastev, Miroslav

126

Experimental Pavement Delineation Treatments.  

National Technical Information Service (NTIS)

In 1975, 43 test sections of various delineation treatments were installed in an attempt to develop treatments with better visibility and durability than the color-contrast and synthetic-binder-concrete then used in New York State to delineate shoulders a...

J. E. Bryden R. A. Lorini

1981-01-01

127

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

SciTech Connect

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

Quinn, J. J.; Environmental Science Division

2006-12-22

128

Relationship between self-potential (SP) signals and redox conditions in contaminated groundwater  

Microsoft Academic Search

In situ measurements of redox potential are rather difficult to perform and provide only sparse information on its spatial distribution. To delineate redox fronts in a contaminant plume, the self-potential (SP) method can be a helpful complement to geochemical measurements. Here, we apply the SP method to the Entressen municipal waste landfill (south-eastern France) over a 20 km2 area. The

V. Naudet; A. Revil; J.-Y. Bottero; P. Bégassat

2003-01-01

129

Mapping groundwater contamination using dc resistivity and VLF geophysical methods -- A case study  

SciTech Connect

Geophysical methods can be helpful in mapping areas of contaminated soil and groundwater. Electrical resistivity and very low-frequency electromagnetic induction (VLF) surveys were carried out at a site of shallow hydrocarbon contamination in Utah County, Utah. Previously installed monitoring wells facilitated analysis of water chemistry to enhance interpretation of the geophysical data. The electrical resistivity and VLF data correlate well, and vertical cross-sections and contour maps generated from these data helped map the contaminant plume, which was delineated as an area of high interpreted resistivities.

Benson, A.K.; Payne, K.L.; Stubben, M.A. [Brigham Young Univ., Provo, UT (United States). Dept. of Geology and Geophysics

1997-01-01

130

Integrated characterisation of aquifer heterogeneity and landfill leachate plume migration  

NASA Astrophysics Data System (ADS)

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

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

2009-05-01

131

Spatial interpolation methods for nonstationary plume data.  

PubMed

Plume interpolation consists of estimating contaminant concentrations at unsampled locations using the available contaminant data surrounding those locations. The goal of ground water plume interpolation is to maximize the accuracy in estimating the spatial distribution of the contaminant plume given the data limitations associated with sparse monitoring networks with irregular geometries. Beyond data limitations, contaminant plume interpolation is a difficult task because contaminant concentration fields are highly heterogeneous, anisotropic, and nonstationary phenomena. This study provides a comprehensive performance analysis of six interpolation methods for scatter-point concentration data, ranging in complexity from intrinsic kriging based on intrinsic random function theory to a traditional implementation of inverse-distance weighting. High resolution simulation data of perchloroethylene (PCE) contamination in a highly heterogeneous alluvial aquifer were used to generate three test cases, which vary in the size and complexity of their contaminant plumes as well as the number of data available to support interpolation. Overall, the variability of PCE samples and preferential sampling controlled how well each of the interpolation schemes performed. Quantile kriging was the most robust of the interpolation methods, showing the least bias from both of these factors. This study provides guidance to practitioners balancing opposing theoretical perspectives, ease-of-implementation, and effectiveness when choosing a plume interpolation method. PMID:15035584

Reed, Patrick M; Ellsworth, Timothy R; Minsker, Barbara S

132

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

133

Three-dimensional contaminant plume dynamics in the vadose zone: Simulation of the 241-T-106 single-shell tank leak at Hanford  

SciTech Connect

Approximately 2,000 m{sup 3} of liquid containing radioactive and chemical wastes leaked from the 241-T-106 single-shell tank at the Hanford Site. The leak discharged into the unsaturated, coarse-grained sediments of the Hanford formation which underlie the base of the tank. The PORFLO-3 computer code was used to study plume migration for {sup 106}Ru and {sup 137}Cs. The flow and transport properties of the soils through which the plume has migrated are critical input data for the model but are not available. Information from a catalogue of Hanford Site soil properties was used. The transient magnitudes and locations of the plume were simulated in three dimensions. Using the reduced vertical hydraulic conductivity, the migration of {sup 106}Ru and {sup 137}Cs was simulated for the time between 1973 and 1990. 24 refs., 33 figs., 3 tabs.

Smoot, J.L.; Sagar, B.

1990-01-01

134

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

135

Anatomy of a Pathological Mantle Plume  

NASA Astrophysics Data System (ADS)

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

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

2008-12-01

136

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.

137

Screening for Groundwater Contaminants Discharging to Urban Streams  

NASA Astrophysics Data System (ADS)

Groundwater contaminated with urban pollutants can adversely affect freshwater aquatic ecosystems where it discharges to streams, lakes or wetlands. Generally such occurrences have been revealed following the discovery of contaminated groundwater plumes at a particular site or from wells in the area. Thus, this contaminant pathway tends to be dealt with on a site-specific and aquifer-focused basis. In contrast, surface water contaminant monitoring typically relies on bulk water concentrations from one or a small set of locations, thus ignoring the spatial variation in contaminant loading, potential losses to sediment or the atmosphere, and the full range of benthic components of the aquatic ecosystem. There are few studies outlining the extent of this contamination from the perspective of the surface water body's deeper benthic community, which might be expected to experience the greatest contaminant concentrations, on more than a local-scale. In this study, we report on an approach to stream-reach-screening for urban contaminants in discharging groundwater, with the focus on detection rather than accurate quantification. The methodology consists of a drive-point technique for sampling groundwater from below the stream bed (e.g. typically 50 cm) along a chosen reach at intervals of about 10 m. Groundwater samples were then analyzed for a wide range of common urban contaminants and general chemistry. This screening method was performed in three urban settings in Canada with known groundwater contamination, covering sections of about 140 to >500 m. The known contaminant plumes at each site were detected and roughly delineated. In addition, potential areas of previously-unknown groundwater contamination were also identified at each site. Contaminants included BTEX and other petroleum hydrocarbons, various chlorinated solvent compounds, nitrate, 1,4-dioxane, MTBE and elevated chloride (likely indicating road salt). These preliminary findings suggest that this approach may be useful for quickly assessing the cumulative threat to aquatic ecosystems of potentially multiple groundwater contaminant sources discharging to surface water bodies in urban settings.

Roy, J. W.; Bickerton, G.; Voralek, J.

2009-05-01

138

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

139

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

140

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

141

Numerical Modeling of One-Dimensional Steady-State Flow and Contaminant Transport in a Horizontally Heterogeneous Unconfined Aquifer with an Uneven Base  

Microsoft Academic Search

Algorithms and a short description of the D1_Flow program for numerical modeling of one-dimensional steady-state flow in horizontally heterogeneous aquifers with uneven sloping bases are presented. The algorithms are based on the Dupuit-Forchheimer approximation. The program permits evaluation of water table elevations, tracking streamlines, delineating bounds of contaminant plume, and estimating advective travel times. The D1_Flow program was tested against

V. Gorokhovski; J. W. Weaver

2008-01-01

142

Using tree core samples to monitor natural attenuation and plume distribution after a PCE spill.  

PubMed

The potential of using tree core samples to detect and monitor natural attenuation of perchloroethene (PCE) in groundwater was investigated at a PCE-contaminated site. In the area of the known plume with PCE concentrations between 0.004 and > 40 mg/L, cores were collected from tree trunks at a height of about 1 m above ground surface. Tree sampling of the site was completed in under six hours. Chlorinated ethenes were analyzed by headspace GC/MS. PCE (0.001 to 7 mg/ kg) and natural attenuation products, TCE (< 0.001 to 0.4 mg/ kg) and c-DCE (< 0.001 to 0.46 mg/kg), were detected in tree cores. 1,1-dichloroethene and vinyl chloride were not detected, corresponding to very low concentrations in the groundwater. The contaminant plume was mapped from the concentrations measured in trees, which delineated a probable hot spot area that had been undetected in decades of traditional groundwater monitoring. Natural attenuation products in tree cores increased with distance from the known source area. Concentrations of PCE and reductive dechlorination products in tree cores were correlated with the corresponding groundwater concentrations. Within a range of limitations, tree-core sampling provides a rapid, reliable and inexpensive method to investigate the extent of shallow contamination by chlorinated ethenes in soil and groundwater. PMID:18441825

Larsen, Morten; Burken, Joel; Machackova, Jirina; Karlson, Ulrich Gosewinkel; Trappt, Stefan

2008-03-01

143

Experimental pavement delineation treatments  

NASA Astrophysics Data System (ADS)

Visibility and durability of materials used to delineate shoulders and medians adjacent to asphalt pavements were evaluated. Materials evaluated were polysulfide and coal tar epoxies, one and two component polyesters, portland cement, acrylic paints, modified-alkyd traffic paint, preformed plastic tape, and thermoplastic markings. Neat applications, sand mortars, and surface treatments were installed in several geometric patterns including cross hatches, solid median treatments, and various widths of edge lines. Thermoplastic pavement markings generally performed very well, providing good visibility under adverse viewing conditions for at least 4 years. Thermoplastic 4 in. wide edge lines appear to provide adequate visibility for most conditions.

Bryden, J. E.; Lorini, R. A.

1981-06-01

144

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

USGS Publications Warehouse

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

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

1986-01-01

145

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

146

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

National Technical Information Service (NTIS)

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 th...

R. C. Star

2005-01-01

147

Chemical barriers for controlling groundwater contamination  

Microsoft Academic Search

Chemical barriers are being explored as a low-cost means of controlling groundwater contamination. The barrier can intercept a contaminant plume and prevent migration by transferring contaminants from the groundwater to immobile solids. A chemical barrier can be emplaced in a landfill liner or in an aquifer cutoff wall or can be injected into a contaminant plume. Chemical barriers can be

S. J. Morrison; R. R. Spangler

1993-01-01

148

The determination of the internal structure of an effluent plume using MSS data  

Microsoft Academic Search

Multispectral scanner (MSS) data from a series of four flights over the Edinburgh sea outfall in the Firth of Forth have been analysed. The data reveal the existence of an integrated surface sewage plume resulting from discharge from a number of sub-surface vertical riser pipes connected to an outfall tunnel. After further processing, the structure of the plume is delineated

P. A. DAVIES; J. A. CHARLTON

1987-01-01

149

The dynamics of buoyant, rotational river plumes  

NASA Astrophysics Data System (ADS)

River plumes are an important and dynamic component of the coastal landscape, delivering nutrients, contaminants, marine organisms, and sediments to shelf waters and shaping habitats that support some of the most diverse and productive ecosystems on earth. In this dissertation, I address the following question. In large-scale rotational plumes, what determines the flux of river water away from the river mouth? Evidence from satellite and field data suggests that many river plumes exhibit a regime in which an anticyclonic bulge forms at the mouth. This regime has been reproduced in a number of numerical studies forced only by a steady, buoyant inflow. In these models the bulge is identified as an unsteady feature that accumulates a fraction of the inflowing river water, thereby decreasing the transport of river water along the coast. I conduct experiments on a 2-meter rotating table, combining Digital Particle Image Velocimetry (DPIV) and Planar Laser Induced Fluorescence (PLIF) to obtain simultaneous measurements of density and velocity in an idealized buoyant plume. The goal of these experiments is to understand how the structure of the anticyclonic bulge depends on the relative strength of buoyant and rotational forcing of the plume and to determine how they modify the transport away from the river mouth in the coastal current. The results of these experiments provide three principal contributions to the understanding of river plume dynamics. First, they confirm that the unsteady plume structure observed in numerical models is an accurate description of an idealized buoyant rotational plume. Second, they define time dependent scales for the radius and depth of the bulge and show that they are consistent with the observed reduction in coastal current transport. The bulge radius and depth are characterized by inertial and geostrophic scales, respectively. Third, they demonstrate that the structure and alongshore transport in river plumes are strongly modified by the inflow angle and that plumes with low inflow angles are steady.

Horner-Devine, Alexander R.

150

Cooling Tower Plume Model.  

National Technical Information Service (NTIS)

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....

L. D. Winiarski W. E. Frick

1976-01-01

151

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

Microsoft Academic Search

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

Robert C. Starr

2005-01-01

152

Paducah Gaseous Diffusion Plant Northwest Plume interceptor system evaluation  

SciTech Connect

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 was to determine the optimum (minimal) well field pumping rates required for plume hotspot containment. Plume hotspot, as defined in the Northwest Plume ROD and throughout this report, is that portion of the plume with trichloroethene (TCE) concentrations greater than 1,000 {micro}g/L. An existing 3-dimensional groundwater model was modified and used to perform capture zone analyses of the north and south interceptor system well fields. Model results suggest that the plume hotspot is not contained at the system design pumping rate of 100 gallons per minute (gal/min) per well field. Rather, the modeling determined that north and south well field pumping rates of 400 and 150 gal/min, respectively, are necessary for plume hotspot containment. The difference between the design and optimal pumping rates required for containment can be attributed to the discovery of a highly transmissive zone in the vicinity of the two well fields.

Laase, A.D.; Clausen, J.L.

1998-07-01

153

Colloid formation at waste plume fronts.  

PubMed

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 degrees 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 nanometers to a few micrometers. Calcium carbonate is always one of the dominant phases of the plume front colloids, while the other phases varied with solution pH and temperature. During infiltration of the leaked high-Na+ waste solution, rapid and completed Na+ replacement of exchangeable Ca2+ and Mg2+ from the sediment caused accumulation of these divalent cations at the moving plume front. Precipitation of supersaturated Ca2+/Mg2+-bearing minerals caused dramatic pH reduction atthe 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. PMID:15573608

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

2004-11-15

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

Containment of subsurface contaminants  

DOEpatents

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

Corey, John C. (Aiken, SC)

1994-01-01

156

Delineation of Free Convection Pathways in a Heterogeneous Low-permeability Unit  

NASA Astrophysics Data System (ADS)

Study of free convection in heterogeneous geologic units poses challenges to hydrogeologists in solute transport modeling and in predicting the effective Rayleigh Number, which is the ratio of bouyancy driving forces to the viscous resistance to flow and the diffusive dissipation of solutes. Downward convection of dense fluid through heterogeneous low-permeability strata follows preferential pathways of groundwater flow and contaminant transport. In this study, the concepts of boundary layer and critical Rayleigh number are used to delineate free convection pathways in a suite of permeability field realizations. A boundary layer is formed when the upward evaporative flux stabilizes the downward groundwater movement in a saline lake environment. Onset of free convection occurs when the effective Rayleigh Number (NRa) exceeds certain value, the critical Rayleigh Number, The threshold value of permeability that permits free convection in a system where denser fluid overlies a less-denser fluid is approximately 10-14 m2 for a boundary layer of 0.315 m and a NRa of 8.5 to 10. Invasion percolation theory (an invasion process that proceeds along a path of least resistance) is used in the searching algorithm that identifies the paths for free convection in 60 different heterogeneous permeability fields. By comparing with modeling results of variable density flow through these different k-simulations, the delineation of pathways provides insight into predicting the occurrence of free convection, groundwater flow, and solute distribution in heterogeneous low-permeability systems. Individual long and wide pathways promote free convection, which indicates that local heterogeneity controls solute transport. Vertically continuous zones of high permeability form pathways that support the initiation and growth of freely-convecting solute plumes.

Shi, M.; Sharp, J. M.

2003-12-01

157

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

158

Dynamics of Thermochemical Plumes  

NASA Astrophysics Data System (ADS)

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

Farnetani, C. G.; Samuel, H.

2004-12-01

159

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

160

Monitoring radioactive plumes by airborne gamma-ray spectrometry  

SciTech Connect

Airborne gamma-ray spectrometer surveys using large volume sodium-iodide detectors are routinely flown throughout the world for mineral exploration and geological mapping. Techniques have now been developed to detect and map man-made sources of radiation. In Canada, airborne gamma-rays surveys have been flown around nuclear reactors to map {sup 41}Ar plumes from nuclear reactors and to calculate the dose rate at ground level. In May 1986, the Finnish Geological survey aircraft flew through a radioactive plume from the Chernobyl nuclear accident. As the aircraft flew through the plume, the aircraft became increasingly contaminated. By measuring the final aircraft contamination, the activity of the plume could be separated from the contamination due to the aircraft. Within 1 h of encountering the plume, the aircraft activity was comparable to the maximum levels found in the plume. From an analysis of the gamma-ray spectra, the concentration of {sup 131}I and {sup 140}La within the plume were calculated as a function of time.

Grasty, R.L. [Exploranium, Mississauga, Ontario (Canada); Hovgaard, J. [Danish Emergency Management Agency, Birkerod (Germany); Multala, J. [Geological Survey of Finland, Espoo (Finland)

1996-06-01

161

Entrainment by Lazy Plumes  

NASA Astrophysics Data System (ADS)

We consider plumes with source conditions that have a net momentum flux deficit compared to a pure plume - so called lazy plumes. We examine both the case of constant buoyancy flux and buoyancy flux linearly increasing with height. By re-casting the plume conservation equations (Morton, Taylor & Turner 1956) for a constant entrainment coefficient ((?)) in terms of the plume radius (?) and the dimensionless parameter (?=frac5Q^2 B4? M^5/2) we show that the far-field flow in a plume with a linear internal buoyancy flux gain is a constant velocity lazy plume with reduced entrainment and radial growth rate. For highly lazy source conditions we derive first-order approximate solutions which indicate a region of zero entrainment near the source. These phenomena have previously been observed, however, it has often been assumed that reduced entrainment implies a reduced (?). We demonstrate that a constant (?) formulation is able to capture the behaviour of these reduced entrainment flows. Morton, B. R., Taylor, G. I. & Turner, J. S. (1956), Turbulent gravitational convection from maintained and instantaneous sources.', Proc. Roy. Soc. 234, 1-23.

Kaye, Nigel; Hunt, Gary

2004-11-01

162

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

163

Detection of heavy metal and hydrocarbon contamination using a miniature resistivity probe.  

PubMed

The usefulness of the electrical resistivity method for characterization of contaminated sites has been studied in many ways. The most commonly used device is a cone penetrometer that utilizes two or four electrodes to measure electrical resistivity (or conductivity) during a cone penetration test (CPT) along a vertical or horizontal alignment. This paper introduces a new miniature resistivity probe (MRP) that can potentially be deployed from a sampling platform to detect contaminant plumes prior to collecting soil samples. Following bench-scale tests aimed at quantifying the sensitivity of the MRP to various operating and environmental parameters, the response of the MRP in sandy soil containing various concentrations of tour heavy metals (Cu, Zn, Pb and Ni) and two hydrocarbons (phenol and gasoline) is evaluated. The test data revealed that the MRP has the potential to serve as an indexing tool for rapidly delineating contaminant plumes where heavy metals are present. The results for hydrocarbons were less conclusive, ranging from moderate ability to differentiate contaminated and non-contaminated soils for phenol to poor differentiation ability for gasoline. PMID:17624110

Ahn, T; Allouche, E N; Yanful, E K

2007-06-01

164

Prometheus: Io's wandering plume.  

PubMed

Unlike any volcanic behavior ever observed on Earth, the plume from Prometheus on Io has wandered 75 to 95 kilometers west over the last 20 years since it was first discovered by Voyager and more recently observed by Galileo. Despite the source motion, the geometric and optical properties of the plume have remained constant. We propose that this can be explained by vaporization of a sulfur dioxide and/or sulfur "snowfield" over which a lava flow is moving. Eruption of a boundary-layer slurry through a rootless conduit with sonic conditions at the intake of the melted snow can account for the constancy of plume properties. PMID:10817989

Kieffer, S W; Lopes-Gautier, R; McEwen, A; Smythe, W; Keszthelyi, L; Carlson, R

2000-05-19

165

Ultraviolet Plume Instrument (UVPI).  

National Technical Information Service (NTIS)

The Ultraviolet Plume Instrument (UVPI) was launched aboard the Low-power Atmospheric Compensation Experiment (LACE) satellite on 14 Feb. 1990. Both the spacecraft and the UVPI were sponsored by the Directed Energy Office of the Strategic Defense Initiati...

D. M. Horan

1993-01-01

166

Enceladus' water vapor plume.  

PubMed

The Cassini spacecraft flew close to Saturn's small moon Enceladus three times in 2005. Cassini's UltraViolet Imaging Spectrograph observed stellar occultations on two flybys and confirmed the existence, composition, and regionally confined nature of a water vapor plume in the south polar region of Enceladus. This plume provides an adequate amount of water to resupply losses from Saturn's E ring and to be the dominant source of the neutral OH and atomic oxygen that fill the Saturnian system. PMID:16527971

Hansen, Candice J; Esposito, L; Stewart, A I F; Colwell, J; Hendrix, A; Pryor, W; Shemansky, D; West, R

2006-03-10

167

Membrane Interface Probe (MIP) for expedited DNAPL delineation  

Microsoft Academic Search

The Membrane Interface Probe (MIP) is a rapid, high-resolution in-situ VOC screening technology that provides real-time data about relative VOC concentrations and soil lithology, as well as the presence of ionic contaminants or a salt-water intrusion. The MIP Technology has been successfully utilized on a number of sites for the purposes of DNAPL delineation and characterization. The technology demonstrated good

Alex Nadolishny; Michael T. Fraser

168

Do Plumes Suck?  

NASA Astrophysics Data System (ADS)

Geophysical observations at plumes, ridges, and arcs indicate that the the volcanic accretionary zone is much narrower than the inferred melt production region in the upwelling mantle. For ridges and arcs, lateral pressure gradients induced by advection of viscous asthenospheric mantle have been proposed as a potential mechanism for focusing melts to the accretionary center [Phipps Morgan, 1987; Spiegelman and McKenzie, 1987]. For ridges and arcs with asthenospheric viscosities >=1021 Pa?s, the magnitude of the lateral pressure gradients associated with viscous corner flow are comparable to vertical melt buoyancy (? ? g). Plumes, however, differ from ridges and arcs in that mantle flow is driven primarily by buoyancy of the upwelling solid as opposed to viscous drag induced by surface plate motions. This difference in driving forces changes the relationship between the solid flow field and the resulting pressure gradients. We use numerical models to examine the influence of lateral pressure gradients from solid advection in plumes. We calculate the stream function and pressure field in the solid induced by a buoyant cylinder beneath a stationary lithosphere using the method of Ribe and Christensen [1999] after Pozrikidis [1997]. Initial results suggest that lateral pressure gradients may draw melt into the top of the plume towards the flow stagnation point. However, the largest flow-induced pressure gradients are oriented vertically within the buoyant plume. Compression where the plume impinges on the lithospheric lid has the potential to impede the vertical migration of melt within the plume. The magnitude of the flow-induced pressure gradients scales with the strength of the buoyant upwelling. However, unlike ridges and arcs, asthenospheric viscosity has little effect on the pressure gradients, because velocity and viscosity of plume material are interdependent. We explore the possible role of these pressure gradients in melt migration at plume and ridge-plume environments. Phipps Morgan, J., Melt migration beneath mid-ocean spreading centers, Geophys. Res. Lett., 14 (12), 1238-1241, 1987. Pozrikidis, C., Introduction to theoretical and computational fluid dynamics, 675 pp., Oxford University Press, New York, 1997. Ribe, N.M., and U.R. Christensen, The dynamical origin of Hawaiian volcanism, Earth and Planet. Sci. Lett., 171, 517-531, 1999. Spiegelman, M., and D. McKenzie, Simple 2-D models for melt extraction at mid-ocean ridges and island arcs, Earth and Planetary Science Letters, 83 (1-4), 137-152, 1987.

Braun, M. G.; Sohn, R. A.; Ribe, N. M.

2001-12-01

169

Hot rocket plume experiment - Survey and conceptual design  

NASA Astrophysics Data System (ADS)

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

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

1992-12-01

170

In-situ remediation system and method for contaminated groundwater  

DOEpatents

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

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

1989-01-01

171

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

172

Tomographic Constraints on Plume Imaging  

NASA Astrophysics Data System (ADS)

Recently emotions are running high in the earth science community on the debate whether or not plumes/plume-like structures are existing.\\Much of the seismological evidence for the existence of plumes stems from the tomographic imaging of structures interpreted to be hot spot related or plume-like.\\In this paper we shall review some of the recent results of tomographic imaging of plumes of different scales as well as discuss some tomographic constraints on plume imaging, such as \\# the general limitations of tomographic imaging of deep structures,\\# the issue of resolution and\\# the influence of different methodologies and/or colour-coding on the images and their interpretation.

Achauer, U.

2002-12-01

173

Pb-Hf-Nd-Sr isotope variations along the Galápagos Spreading Center (101°–83°W): Constraints on the dispersal of the Galápagos mantle plume  

Microsoft Academic Search

We report on 45 Pb, Hf, Nd, and Sr isotope ratios in basalt glasses from the Galápagos Spreading Center (GSC) from 101°W to 83°W, along with related parent and daughter element concentrations. The purpose is to delineate the effect of the Galápagos mantle plume on this NE migrating spreading ridge and the nature of the plume dispersion in the region.

Jean-Guy Schilling; Denis Fontignie; Janne Blichert-Toft; Richard Kingsley; Urszula Tomza

2003-01-01

174

Pb-Hf-Nd-Sr isotope variations along the Galápagos Spreading Center (101°-83°W): Constraints on the dispersal of the Galápagos mantle plume  

Microsoft Academic Search

We report on 45 Pb, Hf, Nd, and Sr isotope ratios in basalt glasses from the Galápagos Spreading Center (GSC) from 101°W to 83°W, along with related parent and daughter element concentrations. The purpose is to delineate the effect of the Galápagos mantle plume on this NE migrating spreading ridge and the nature of the plume dispersion in the region.

Jean-Guy Schilling; Denis Fontignie; Janne Blichert-Toft; Richard Kingsley; Urszula Tomza

2003-01-01

175

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

PubMed

An application of a newly developed optimal monitoring network for the delineation of contaminants in groundwater is demonstrated in this study. Designing a monitoring network in an optimal manner helps to delineate the contaminant plume with a minimum number of monitoring wells at optimal locations at a contaminated site. The basic principle used in this study is that the wells are installed where the measurement uncertainties are minimum at the potential monitoring locations. The development of the optimal monitoring network is based on the utilization of contaminant concentration data from an existing initial arbitrary monitoring network. The concentrations at the locations that were not sampled in the study area are estimated using geostatistical tools. The uncertainty in estimating the contaminant concentrations at such locations is used as design criteria for the optimal monitoring network. The uncertainty in the study area was quantified by using the concentration estimation variances at all the potential monitoring locations. The objective function for the monitoring network design minimizes the spatial concentration estimation variances at all potential monitoring well locations where a monitoring well is not to be installed as per the design criteria. In the proposed methodology, the optimal monitoring network is designed for the current management period and the contaminant concentration data estimated at the potential observation locations are then used as the input to the network design model. The optimal monitoring network is designed for the consideration of two different cases by assuming different initial arbitrary existing data. Three different scenarios depending on the limit of the maximum number of monitoring wells that can be allowed at any period are considered for each case. In order to estimate the efficiency of the developed optimal monitoring networks, mass estimation errors are compared for all the three different scenarios of the two different cases. The developed methodology is useful in coming up with an optimal number of monitoring wells within the budgetary limitations. The methodology also addresses the issue of redundancy, as it refines the existing monitoring network without losing much information of the network. The concept of uncertainty-based network design model is useful in various stages of a potentially contaminated site management such as delineation of contaminant plume and long-term monitoring of the remediation process. PMID:20390346

Chadalavada, Sreenivasulu; Datta, Bithin; Naidu, Ravi

2011-02-01

176

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

177

Performance comparison of interceptor trench configurations for extracting contaminated groundwater.  

PubMed

Computer simulations tested the capability of five alternative interceptor trench configurations to capture an enclave (plume) of contaminated groundwater. The configurations included a single linear segment and angled segments, at 90 degrees and 135 degrees, with a common endpoint. Alternative angled configurations both faced and opposed the contaminant plume. Each trench configuration had the same total length and was located the same average distance from the contaminant plume. The minimum pumping rate required to capture the plume and a surrounding buffer zone, within a prescribed time period, was determined for each trench configuration. The 90 degree plume-opposed trench performed best, requiring approximately one-third the pumping rate of the 90 degree plume-facing configuration. The plume-opposed configuration yielded a capture zone that best conformed to the actual shape of the contaminant plume, thereby reducing the amount of groundwater that had to be removed from the aquifer to remove the contaminant plume. Ironically, plume opposed configurations are rarely used in practice. Results of this study suggest that alternative interceptor trench configurations, including funnels with mouths opposed to contaminant plumes, should be tested with computer simulations when devising protocols for groundwater remediation. PMID:15137698

Hudak, Paul F

2004-01-01

178

Colloid Formation and Transport at Waste Plume Fronts  

NASA Astrophysics Data System (ADS)

We have recently identified the phenomenon of massive colloid formation and transport within moving waste plume fronts during infiltration of high-salinity waste solutions into sediments. Colloid formation and transport was thousands of times higher within a narrow zone at the moving plume front than in the plume body and the leaching stage. The newly formed plume front colloids were primarily in the size range from tens of nm to a few micron meters. The underlying process begins with rapid and completed cation exchange of Na+ from the infiltrating waste solution replacing Ca2+ and Mg2+ from the sediments, coupled with flow of the infiltrating waste solution enriched these divalent cations within the moving plume front. Subsequent precipitation of colloids containing these divalent cations released protons and reduced the plume front pH to as low as neutral. This substantially reduced pH in turn promoted precipitation of other pH sensitive minerals and amorphous phases as colloids. This plume front colloid generation phenomenon can occur under a wide range of conditions including sediment type, waste solution pH, temperature, and chemical composition, with the only necessary condition being that of a high ionic strength waste solution. Because of the large mass of suspended colloids generated, this phenomenon could significantly affect the fate and transport of the contaminant trace elements contained within the waste plumes. Depending on the chemical properties of the individual radionuclide or toxic metal, it can co-precipitate with or adsorb onto the plume front colloids. As an example, uranium was predicted and found preferentially precipitated as a mobile colloid phase within a uranium waste plume front. Funding of this research was provided by the Geosciences Research Program of Basic Energy Science, U.S. Department of Energy.

Wan, J.; Tokunaga, T. K.; Larsen, J. T.; Zheng, Z.

2004-12-01

179

Evidence for mantle plumes?  

PubMed

Geophysical hotspots have been attributed to partially molten asthenosphere, fertile blobs, small-scale convection and upwellings driven by core heat. Most are short-lived or too close together to be deeply seated, and do not have anomalous heat flow or temperature; many are related to tectonic features. Bourdon et al. investigate the dynamics of mantle plumes from uranium-series geochemistry and interpret their results as evidence for thermal plumes. Here we show why alternative mechanisms of upwelling and melting should be considered. PMID:18033248

Anderson, Don L; Natland, James H

2007-11-22

180

Data sufficiency analysis and assessment of uncertainty before and after detection of a leachate plume from a municipal landfill  

NASA Astrophysics Data System (ADS)

Groundwater contamination from municipal landfill leachate consisting of halogenated volatile organic compounds and petroleum byproducts in northeastern New York State was delineated between 1993 and 1995 and has been undergoing remediation since 1998. Elevated concentrations of leachate indicators (i.e. BOD5, TSS, chloride, and Specific Conductance) were identified in several downgradient monitoring wells as early as 1986. This case study involves a statistical power analysis for the landfill's detection and monitoring wells for two distinct time periods: (1) prior to plume delineation with limited data, and (2) post construction of monitoring wells and examination of additional exploratory borings. Traditional multivariate and geostatistical techniques (cokriging) were combined with a sufficiency analysis and uncertainty assessment to evaluate the importance of multiple data types at monitoring well locations. We address whether a sufficient number of monitoring locations existed to determine, within a particular confidence interval, that a regulatory concentration was not exceeded at specified spatial locations; whether the current sampling frequency is sufficient (or redundant) at monitoring locations; and give estimates of uncertainty at spatial locations of interest.

Rizzo, D. M.; Mouser, P. J.

2004-05-01

181

EVALUATION OF NATURAL AND IN-SITU REMEDIATION TECHNOLOGIES FOR A COAL-RELATED METALS PLUME  

Microsoft Academic Search

Metals contamination exceeding drinking water standards (MCLs) is associated with acidic leachate generated from a coal pile runoff basin at the Savannah River Site (SRS) in Aiken, South Carolina. The metals plume extends over 100 acres with its' distal boundary about onehalf mile from the Savannah River. Based on the large plume extent and high dissolved iron and aluminum concentrations,

Jeffrey A. Ross; Cassandra L. Bayer; Ronald P. Socha; Cynthia S. Sochor; Carl B. Fliermans; Pamela C. McKinsey; Margaret R. Millings; Mark A. Phifer; Kimberly R. Powell; Steven M. Serkiz; Frank C. Sappington; Charles E. Turick

2003-01-01

182

SIMPLIFIED SOIL GAS SENSING TECHNIQUES FOR PLUME MAPPING AND REMEDIATION MONITORING  

EPA Science Inventory

Soil gas measurements were taken in a beach sand matrix of the unsaturated zone above a ground water plume contaminated from a spill near 35,000 gallons of aviation gasoline. he soil gas sampling and analysis strategy provided required information for mapping the plume and vertic...

183

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

USGS Publications Warehouse

Stormwater plumes in the southern California coastal ocean were detected by MODIS-Aqua satellite imagery and compared to ship-based data on surface salinity and fecal indicator bacterial (FIB) counts collected during the Bight'03 Regional Water Quality Program surveys in February-March of 2004 and 2005. MODIS imagery was processed using a combined near-infrared/shortwave-infrared (NIR-SWIR) atmospheric correction method, which substantially improved normalized water-leaving radiation (nLw) optical spectra in coastal waters with high turbidity. Plumes were detected using a minimum-distance supervised classification method based on nLw spectra averaged within the training areas, defined as circular zones of 1.5-5.0-km radii around field stations with a surface salinity of S 33.0 ('ocean'). The plume optical signatures (i.e., the nLw differences between 'plume' and 'ocean') were most evident during the first 2 days after the rainstorms. To assess the accuracy of plume detection, stations were classified into 'plume' and 'ocean' using two criteria: (1) 'plume' included the stations with salinity below a certain threshold estimated from the maximum accuracy of plume detection; and (2) FIB counts in 'plume' exceeded the California State Water Board standards. The salinity threshold between 'plume' and 'ocean' was estimated as 32.2. The total accuracy of plume detection in terms of surface salinity was not high (68% on average), seemingly because of imperfect correlation between plume salinity and ocean color. The accuracy of plume detection in terms of FIB exceedances was even lower (64% on average), resulting from low correlation between ocean color and bacterial contamination. Nevertheless, satellite imagery was shown to be a useful tool for the estimation of the extent of potentially polluted plumes, which was hardly achievable by direct sampling methods (in particular, because the grids of ship-based stations covered only small parts of the plumes detected via synoptic MODIS imagery). In most southern California coastal areas, the zones of bacterial contamination were much smaller than the areas of turbid plumes; an exception was the plume of the Tijuana River, where the zone of bacterial contamination was comparable with the zone of plume detected by ocean color. ?? 2008 Elsevier Ltd.

Nezlin, N. P.; DiGiacomo, P. M.; Diehl, D. W.; Jones, B. H.; Johnson, S. C.; Mengel, M. J.; Reifel, K. M.; Warrick, J. A.; Wang, M.

2008-01-01

184

Chemical Plume Source Localization  

Microsoft Academic Search

This paper addresses the problem of estimating a likelihood map for the location of the source of a chemical plume using an autonomous vehicle as a sensor probe in a fluid flow. The fluid flow is assumed to have a high Reynolds number. Therefore, the dispersion of the chemical is dominated by turbulence, resulting in an intermittent chemical signal. The

Shuo Pang; Jay A. Farrell

2006-01-01

185

Buoyant plume calculations  

SciTech Connect

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

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

1985-01-01

186

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

187

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

188

A numerical investigation into factors affecting gas and aqueous phase plumes in the subsurface  

Microsoft Academic Search

An investigation into the face and transport of volatile organic compounds (VOCs) in the subsurface requires the consideration of contaminant mass in both the aqueous and soil gas phases. As a result of water\\/gas phase partitioning, contaminated by partitioning from underlying ground water pollution. Conversely, soil gas can be contaminated by partitioning from underlying ground water VOC plumes. This soil

N. R. Thomson; J. F. Sykes; D. Van Vliet

1997-01-01

189

Electrical resistivity imaging of conductive plume dilution in fractured rock  

NASA Astrophysics Data System (ADS)

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

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

2007-08-01

190

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

NASA Astrophysics Data System (ADS)

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

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

2006-12-01

191

Scanning thermal plumes  

Microsoft Academic Search

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

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

1975-01-01

192

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

193

Length of Steady-State Plumes: Uncertainty Analysis in two-Dimensional Heterogeneous Porous Media  

NASA Astrophysics Data System (ADS)

We consider contaminant plumes in groundwater originating from continuous sources. Assuming a sufficiently fast reaction between an organic contaminant, released from the source, and a dissolved electron acceptor, originating from ambient groundwater flow, the process limiting overall degradation is transverse mixing of the reactants. For an instantaneous, irreversible, complete reaction, the plume approaches a definite length that scales with the squared width at the source and the inverse transverse dispersion coefficient in case of a homogeneous aquifer and identical mixing coefficients for both reactants. Heterogeneity of hydraulic conductivity affects the volume flux passing through the source zone and the effective transverse mixing along the plume fringe. The correct parameterization of transverse dispersion at the local scale also affects transverse mixing at larger scales. In this work, we analyze the uncertainty in predicting the length of plumes originating from continuous sources that are attenuated by dilution and transverse mixing. We account for three sources of uncertainty: (i) parameterization of Darcy-scale transverse dispersion coefficient, (ii) uncertainty of effective mixing along the plume fringe in heterogeneous media, and (iii) uncertainty of the plume's mass flux leaving the source, caused by heterogeneity within the source area. We derive semi-analytical expressions for the probability distribution of plume length, accounting for correlation between source strength and effective mixing. The results are compared to Monte Carlo simulations and indicate that the choice of different parameterizations of the local dispersion coefficient lead to a systematic error in the estimation of the plume length, while uncertainties affecting mixing and the source mass flux result in a statistical distribution of the possible plume lengths. For unconditional random conductivity fields, plume lengths may vary by more than one order of magnitude even for a moderate degree of heterogeneity. The uncertainty affecting the contaminant mass flux at the source is found to be the most relevant contribution to the variance of the plume length.

Chiogna, G.; Rolle, M.; de Barros, F.; Nowak, W.; Cirpka, O. A.

2011-12-01

194

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,...

195

Foreshore study through shoreline delineation  

NASA Astrophysics Data System (ADS)

The study of the foreshore is of considerable interest to the environmental science community, and the advent of regular SAR imagery from the ERS, Radarsat and JERS satellites has offered the opportunity to monitor continuously this dynamic region. Knowledge of foreshore topography is of use in improving flood prediction models, measuring sediment flux, and assessing the effectiveness of sea defences. Conventional surveying is the expensive, time consuming and often hazardous current technique often employed to obtain these data. The alternative technique presented here involves a semi-automatic process to delineate the shoreline on a number of ERS SAR images, and a model to calculate the sea heights at the time the images were taken. By combining these data a set of quasi-contours is generated, and from these it is possible to devise a digital elevation model of the foreshore. Each of these quasi-contours is associated with the time its image was taken, and it is therefore necessary to interpolate in time and space. Such interpolation allows the creation of time- dependent DEMs which can be used to study the long-term evolution of the foreshore. This paper demonstrates the technique by following its application to the length of UK coastline of most interest to the NERC Land-Ocean Interaction Study Community Programme, the 100km from the Humber estuary to the Wash. The INDUS project funded under the British National Space Centre Earth Observation LINK scheme is further refining the accuracy of the technique and extending its application to cover more of the coastal regions of the UK, as well as establishing the requirements of users.

Davenport, Ian J.; Mason, D. C.; Flather, R. A.; Gurney, C.

1996-12-01

196

Hydraulic gradient control for groundwater contaminant removal  

USGS Publications Warehouse

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

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

1985-01-01

197

Stirring and structure in mantle starting plumes  

Microsoft Academic Search

Simple arguments show that ascending thermal plumes will entrain their surroundings as the result of coupling between conduction of heat and laminar stirring driven by the plume motion. In the initial stages of ascent of a plume fed by a continuous buoyancy flux (a starting plume) the plume consists of a large buoyant head followed by a narrow vertical conduit.

Ross W. Griffiths; Ian H. Campbell

1990-01-01

198

Effect of plume processes on aircraft impact  

Microsoft Academic Search

A versatile Gaussian plume model has been developed and used to investigate the chemistry in expanding aircraft plumes for a wide range of conditions, including the plume expansion rate, the composition of the background atmosphere, and the total time of the plume integration. The dependence of plume processing on altitude, latitude and season has been investigated in order to generate

P. F. Vohralik; L. K. Randeniya; I. C. Plumb; S. L. Baughcum

2008-01-01

199

Upwelling relaxation and estuarine plumes  

NASA Astrophysics Data System (ADS)

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

Rao, Shivanesh; Pringle, James; Austin, Jay

2011-09-01

200

Mantle plumes and continental tectonics.  

PubMed

Mantle plumes and plate tectonics, the result of two distinct modes of convection within the Earth, operate largely independently. Although plumes are secondary in terms of heat transport, they have probably played an important role in continental geology. A new plume starts with a large spherical head that can cause uplift and flood basalt volcanism, and may be responsible for regional-scale metamorphism or crustal melting and varying amounts of crustal extension. Plume heads are followed by narrow tails that give rise to the familiar hot-spot tracks. The cumulative effect of processes associated with tail volcanism may also significantly affect continental crust. PMID:17744717

Hill, R I; Campbell, I H; Davies, G F; Griffiths, R W

1992-04-10

201

43 CFR 3922.40 - Tract delineation.  

Code of Federal Regulations, 2012 CFR

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

2012-10-01

202

Implementing CD-Based Wetland Delineation Training.  

National Technical Information Service (NTIS)

This technical note presents an implementation plan for the development of a CD- or Internet-based tutorial for individual instruction in wetland identification and delineation. The tutorial is aimed primarily at new personnel in the Corps Regulatory prog...

J. S. Wakeley

2002-01-01

203

Common Wetland Delineation Sedges of the Northeast.  

National Technical Information Service (NTIS)

This field guide is intended to assist in identifying 16 of the most common Carex (sedge) species observed during wetland delineations. And additional 26 species that are similar in appearance to these common sedges are included and distinguished. This gu...

R. Lichvar

2005-01-01

204

Atmospheric chemistry in volcanic plumes.  

PubMed

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

von Glasow, Roland

2010-04-05

205

LAMP Observes the LCROSS Plume  

NASA Video Gallery

This video shows LAMP’s view of the LCROSS plume. The first half of the animation shows the LAMP viewport scanning across the horizon, passing through the plume, and moving on. The second half of the animation shows how data generated from a previous orbit was used to reduce noise in the observed data.

gsfcvideo

2010-10-20

206

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

207

The Ultraviolet Plume Instrument (UVPI)  

Microsoft Academic Search

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

D. M. Horan

1993-01-01

208

Geolectrical methods applied on a contaminated site : the Entressen landfill case study (south-eastern France)  

Microsoft Academic Search

Redox potential is a controlling parameter in many contaminated site remediation technologies. Its knowledge is crutial to understand the contaminant plume development and risks for groundwater ressources. But, redox potential is very difficult to measure directlly in the field. A geophysical method that could determine the redox potential distribution in a contaminant plume would be particularly welcome. We believe that

V. Naudet; A. Revil; J.-Y. Bottero

2003-01-01

209

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

210

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, T.R.; Jones, D.T.H.; Kelly, M.J.; Medernach, J.W.; Stevenson, J.O.; Tsao, S.S.

1990-01-01

211

Spectroscopic characteristics of polar plumes  

NASA Astrophysics Data System (ADS)

Extreme ultraviolet observations of plumes in polar coronal holes are presented and their spectroscopic signatures discussed. The study focuses on the base of plumes seen on the disk of the Sun with the Coronal Diagnostic Spectrometer (CDS) on the Solar and Heliospheric Observatory (SOHO) satellite. Spectroscopic diagnostic techniques are applied to characterise the plumes in terms of density, temperature, emission measure and element abundance. Attention is drawn to the particular limitations of some of the techniques when applied to plume structures. In particular, we revisit the Widing & Feldman (1992) findings of a plume having a large first ionization potential (FIP) effect of 10, showing that instead the Skylab data are consistent with no FIP effect. We present for the first time CDS-GIS (grazing incidence spectrometer) observations of a plume. These observations have been used to confirm the results obtained from normal incidence (NIS) observations. We find that polar plumes exhibit the same characteristics as the Elephant's Trunk equatorial plume. The most striking characteristic of the plume bases is that they are near-isothermal with a peak emission measure at transition region temperatures =~ 8 x 105 K. At these temperatures, plumes have averaged densities Nlo {e} =~ 1.2 x 109 cm-3, about twice the value of the surrounding coronal hole region. Element abundances in the plumes are found to be close to photospheric, with the exception of neon which appears to be depleted by 0.2 dex relative to oxygen. The absence of a significant FIP effect in plumes is consistent with fast solar wind plasma, although it is not sufficient to prove a link between the two. Finally, we present a comparison between GIS spectra and the SOHO EIT (EUV Imaging Telescope) broad-band images, showing that temperatures derived from the EIT ratio technique are largely overestimated, for plumes and coronal holes. This is partly due to the fact that the so called ``Fe XII 195 Å'' and ``Fe XV 284 Å'' filters are not isothermal, and in coronal holes and plumes lower-temperature lines dominate the EIT signal.

Del Zanna, G.; Bromage, B. J. I.; Mason, H. E.

2003-02-01

212

A multivariate statistical approach to spatial representation of groundwater contamination using hydrochemistry and microbial community profiles.  

PubMed

Managers of landfill sites are faced with enormous challenges when attempting to detect and delineate leachate plumes with a limited number of monitoring wells, assess spatial and temporal trends for hundreds of contaminants, and design long-term monitoring (LTM) strategies. Subsurface microbial ecology is a unique source of data that has been historically underutilized in LTM groundwater designs. This paper provides a methodology for utilizing qualitative and quantitative information (specifically, multiple water quality measurements and genome-based data) from a landfill leachate contaminated aquifer in Banisveld, The Netherlands, to improve the estimation of parameters of concern. We used a principal component analysis (PCA) to reduce nonindependent hydrochemistry data, Bacteria and Archaea community profiles from 16S rDNA denaturing gradient gel electrophoresis (DGGE), into six statistically independent variables, representing the majority of the original dataset variances. The PCA scores grouped samples based on the degree or class of contamination and were similar over considerable horizontal distances. Incorporation of the principal component scores with traditional subsurface information using cokriging improved the understanding of the contaminated area by reducing error variances and increasing detection efficiency. Combining these multiple types of data (e.g., genome-based information, hydrochemistry, borings) may be extremely useful at landfill or other LTM sites for designing cost-effective strategies to detect and monitor contaminants. PMID:16245827

Mouser, Paula J; Rizzo, Donna M; Röling, Wilfred F M; Van Breukelen, Boris M

2005-10-01

213

Falling plumes in bacterial bioconvection  

NASA Astrophysics Data System (ADS)

Experiments by Kessler on bioconvection in laboratory suspensions of bacteria (Bacillus subtilis), contained in a deep chamber, reveal the development of a thin upper boundary layer of cell-rich fluid which becomes unstable, leading to the formation of falling plumes. We use the continuum description of such a suspension developed by Hillesdon et al. (1995) as the basis for a theoretical model of the boundary layer and an axisymmetric plume. If the boundary layer has dimensionless thickness [lambda] [double less-than sign] 1, the plume has width [lambda]1/2. A similarity solution is found for the plume in which the cell flux and volume flux can be matched to those in the boundary layer and in the bulk of the suspension outside both regions. The corresponding model for a two-dimensional plume fails to give a self-consistent solution.

Metcalfe, Aisling M.; Pedley, T. J.

2001-10-01

214

Wetlands Management I - Determination and Delineation  

NSDL National Science Digital Library

This instructional guide is designed to provide instructors with lecture and laboratory materials that introduce the concepts and practices of wetland determination and delineation. Student objectives, a general lecture outline and a more detailed PowerPoint presentation with instructor notes are provided. Criteria for the identification of wetlands and accepted delineation methods as established by the U.S. Army Corps of Engineers are reviewed including field indicators of hydric soils, hydrology and wetland vegetation. Various sources of archived information commonly used in wetland determination and delineation are also described. A combination laboratory/field exercise is also fully described that guides students through a hands-on experience to illustrate how determinations are performed and how the boundaries of a wetland are defined. Instructors who are looking for videos or additional print and web-based resources on the topics covered here should consult the resources list provided at the end of this module where these resources are summarized and cited.Upon successful completion of this module students should be able to:* Distinguish between âÂÂwetland determinationâ and âÂÂwetland delineationâÂÂ* Describe the need for wetland identification and delineation in wetland management* Identify current and archived sources of information that could be accessed to perform a wetland determination or delineation* Describe field indicators of wetlands based on soils, hydrology and vegetation criteria

Cudmore, Wynn

2011-09-20

215

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...

216

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

217

Spectroscopic investigation of colliding plasma plumes  

NASA Astrophysics Data System (ADS)

Time-resolved and space-resolved spectroscopic and imaging studies of colliding carbon plumes are reported, with the aim of understanding the dynamics of the ablated plume in comparison to single-plume carbon plasma. Laser produced colliding plumes and single plume were studied under vacuum (of the order 5 × 10- 5 mbar) in a nitrogen environment using a flat graphite target. Due to the interaction of energetic particles of two colliding plumes, a new particle layer is formed that stagnate for a longer time than the seed plasma. Variation of the plume front and dimension of the stagnation layer with time are also reported.

Singh, Ravi Pratap; Gupta, Shyam L.; Thareja, R. K.

2013-10-01

218

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

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

219

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

220

Field evaluation of mixing length and attenuation of nutrients and fecal coliform in a wastewater effluent plume.  

PubMed

We present an alternative method to dye tracer studies for mapping wastewater effluent plumes in rivers. A case study of a wastewater treatment effluent plume that was mapped in two different months (October and April) showed good resolution in determining where the plume reached the opposite river bank, the degree of mixing in a given river reach, and where the river was fully mixed with respect to the plume. Both electrical conductivity and chloride were useful in mapping domestic wastewater effluent plume mixing. Mixing lengths obtained by field mapping were consistent with previous studies. Electrical conductivity field readings facilitated real-time plume delineation and sampling locations, and identified a non-point source plume during the mapping exercise. The apparent difference in dispersion of the plume between to the two mapping dates (despite similar upstream river discharge) suggests that the calibration of a water quality model based on a single dye test may be inadequate. The river distributions of effluent nutrients and fecal coliform were also mapped. Nutrient attenuation rates were faster than that of the chloride tracer, indicating processes other than mixing occur. Substantial differences were observed in nutrient and fecal coliform distributions between the two mapping dates. PMID:16418904

Vandenberg, Jerald A; Ryan, M Cathryn; Nuell, David D; Chu, Angus

2005-08-01

221

Quantifying and Predicting Reactive Transport of Uranium in Waste Plumes  

SciTech Connect

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

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

2005-06-01

222

Electrical Charging of Volcanic Plumes  

NASA Astrophysics Data System (ADS)

Many explosive terrestrial volcanic eruptions are accompanied by lightning and other atmospheric electrical phenomena. The plumes produced generate large perturbations in the surface atmospheric electric potential gradient and high charge densities have been measured on falling volcanic ash particles. The complex nature of volcanic plumes (which contain gases, solid particles, and liquid drops) provides several possible charging mechanisms. For plumes rich in solid silicate particles, fractoemission (the ejection of ions and atomic particles during fracture events) is probably the dominant source of charge generation. In other plumes, such as those created when lava enters the sea, different mechanisms, such as boiling, may be important. Further charging mechanisms may also subsequently operate, downwind of the vent. Other solar system bodies also show evidence for volcanism, with activity ongoing on Io. Consequently, volcanic electrification under different planetary scenarios (on Venus, Mars, Io, Moon, Enceladus, Tethys, Dione and Triton) is also discussed.

James, M. R.; Wilson, L.; Lane, S. J.; Gilbert, J. S.; Mather, T. A.; Harrison, R. G.; Martin, R. S.

223

Electrical Charging of Volcanic Plumes  

NASA Astrophysics Data System (ADS)

Many explosive terrestrial volcanic eruptions are accompanied by lightning and other atmospheric electrical phenomena. The plumes produced generate large perturbations in the surface atmospheric electric potential gradient and high charge densities have been measured on falling volcanic ash particles. The complex nature of volcanic plumes (which contain gases, solid particles, and liquid drops) provides several possible charging mechanisms. For plumes rich in solid silicate particles, fractoemission (the ejection of ions and atomic particles during fracture events) is probably the dominant source of charge generation. In other plumes, such as those created when lava enters the sea, different mechanisms, such as boiling, may be important. Further charging mechanisms may also subsequently operate, downwind of the vent. Other solar system bodies also show evidence for volcanism, with activity ongoing on Io. Consequently, volcanic electrification under different planetary scenarios (on Venus, Mars, Io, Moon, Enceladus, Tethys, Dione and Triton) is also discussed.

James, M. R.; Wilson, L.; Lane, S. J.; Gilbert, J. S.; Mather, T. A.; Harrison, R. G.; Martin, R. S.

2008-06-01

224

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

225

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

SciTech Connect

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

Not Available

1991-10-01

226

Detection of Plastic Explosive Traces in the Human Thermal Plume  

NASA Astrophysics Data System (ADS)

Aviation security requires the detection of explosive devices which terrorists, posing as passengers, may conceal beneath their clothing. Our goal is to understand the generation, transport, and collection of trace signals from such concealed explosives, which are found in the natural convective plume produced by the human body. Previous work (APS/DFD96, CG10) has visualized this plume and shown that concealed volatile explosives (e.g. TNT) produce a detectable vapor signal therein. Plastic explosives, on the other hand, have vanishingly low vapor pressures and are thus considered very difficult to detect. Present experiments use a dispersal chamber to collect and sample the plumes of human subjects wearing concealed gauze patches containing milligrams of RDX, the primary component of plastic explosives such as C-4. These experiments address the effects of agitation, clothing, temperature and humidity on trace detectability. Further experiments address the effects of oily vs. dry skin, contaminated clothing vs. gauze patches, and residual contamination left on skin previously in contact with RDX. The key role of airborne contaminated textile fibers is noted. Knowledge thus gained contributes to the design of an explosive detection portal for aviation security screening. (Research supported by FAA Grant 93-G-052.)

Gowadia, Huban A.; Settles, Gary S.

1998-11-01

227

Wildfire plume electrical conductivity  

NASA Astrophysics Data System (ADS)

Wildfires are weakly ionized gas. The ionization is mainly due to plant's inorganic ash content species (more especially potassium), that are emitted from thermally decomposing plant structure into the flame during combustion. The amount of ionization in flames with potassium impurities is influenced by both the temperature and the amount potassium impurities in the flame. A numerical experiment was conducted using a local thermal equilibrium-based model to study the influence of inorganic wildfire contents on wildfire electrical conductivity. Simulated very high intensity wildfires (21-90 MWm-1) were used to quantify steady-state electrical conductivity. Its variation with wildfire plume height is important for high voltage power flashover research. In the simulation, vegetation potassium content was varied from 0.50% to 3.0% on dry weight basis, a reflection of its content in natural vegetation. The model predicted a maximum conductivity of 0.053 mhom-1 in 90 MWm-1 crown fire in vegetation with 3.0% potassium content. A 90 MWm-1 crown fire in vegetation with potassium content of 0.5% was predicted to produce a maximum conductivity of 0.022 mhom-1. Electrical conductivities were lower for a shrub fire with an intensity of 21 MWm-1. The model predicted conductivities of 0.0021 and 0.0009 mhom-1 for potassium content of 3.0 and 0.5% in vegetation, respectively.

Mphale, Kgakgamatso; Heron, Malcom

2007-09-01

228

Stochastic delineation of well capture zones  

Microsoft Academic Search

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

D. X. Zhang; Z. M. Lu

2004-01-01

229

Plumes, orogenesis, and supercontinental fragmentation  

NASA Astrophysics Data System (ADS)

A time-space relationship between large igneous provinces (LIPS), present day hot spots, and the fragmentation of Pangea has been documented over several decades, but the cause of fragmentation has remained elusive. LIPS are regarded either as the result of impingement of a mantle plume on the base of the lithosphere, or as the initial products of adiabatic decompression melting of anomalously hot mantle. Do LIPS therefore constitute evidence of an active role for plumes from the deep mantle in supercontinental fragmentation, or are they merely the first indications of a large-scale but near-surface tectonic process? Two long recognized and enigmatic orogenic events may offer a solution to this geologically important 'chicken or egg' conundrum. The reconstructed early Mesozoic Gondwanide fold belt of South America, southern Africa, and Antarctica, could have resulted from 'plume-modified orogeny', flattening of a downgoing lithospheric slab due to the buoyancy of a plume rising beneath a continental margin subduction zone. If so, the ˜180 Ma Karroo and Ferrar LIPS associated with the opening of the ocean basin between East and West Gondwanaland at ˜165 Ma resulted from impingement of this plume and are unrelated to the thermal insulation of the shallow mantle beneath Gondwanaland. It would then follow that the plume itself played an active, possibly critical, role in the initial breakup of the supercontinent. The Late Paleozoic 'Ancestral Rockies' deformation in the southwestern United States could be yet another example of orogeny driven by a plume that initiated the break-up of Pangea approximately 15 Myr earlier in the Central Atlantic region.

Dalziel, I. W. D.; Lawver, L. A.; Murphy, J. B.

2000-05-01

230

Viability of longitudinal trenches for capturing contaminated groundwater.  

PubMed

Using a groundwater flow and mass transport model, this study compared the capability of trenches with permeable backfill for capturing hypothetical contaminant plumes in homogeneous and heterogeneous unconfined aquifers. Longitudinal (parallel to groundwater flow), as well as conventional transverse (perpendicular to groundwater flow) trench configurations were considered. Alternate trench configurations intercepted the leading tip of an initial contaminant plume and had identical length, equal to the cross-gradient width of the plume. A longitudinal trench required 31% less time than its transverse counterpart to remediate a homogeneous aquifer. By contrast, in simulated heterogeneous aquifers, longitudinal remediation timeframes ranged from 41% less to 33% more than transverse trenches. Results suggest that longitudinal trenches may be a viable alternative for narrow contaminant plumes under low-groundwater velocity conditions, but may be impractical for plumes with wide leading tips, or in complex heterogeneous aquifers with divergent flow. PMID:20237910

Hudak, Paul F

2010-03-17

231

pH neutralization and zonation in alkaline-saline tank waste plumes.  

PubMed

At the Hanford Site in Washington State, the pH values of contaminant plumes resulting from leaking of initially highly alkaline-saline radioactive waste solutions into the subsurface are now found to be substantially neutralized. However, the nature of plume pH neutralization has not previously been understood. As a master geochemical variable, pH needs to be understood in order to predict the fate and transport of contaminants carried by the waste plumes. Through this laboratory study, we found that the plume pH values spanned a broad range from 14 (within the near-source region) down to the value of 7 (lower than the pH value of the initial soil solution) while the plume was still connected to an actively leaking source. We defined two zones within a plume: the silicate dissolution zone (SDZ, pH 14-10) and the neutralized zone (NZ, pH 10-7). Quartz dissolution at elevated temperature and precipitation of secondary silicates (including sodium metasilicate, cancrinite, and zeolites) are the key reactions responsible for the pH neutralization within the SDZ. The rapid and thorough cation exchange of Na+ replacing Ca2+/Mg2+, combined with transport, resulted in a dynamic Ca2+/Mg2+-enriched plume front. Subsequent precipitation of calcite, sodium silicate, and possibly talc led to dramatically reduced pH within the plume front and the neutralized zone. During aging (after the plume source became inactive), continued quartz dissolution and the secondary silicate precipitation drove the pH value lower, toward pH 11 at equilibrium within the SDZ, whereas the pH values in the NZ remained relatively unchanged with time. A pH profile of 11 from the plume source to pH 7 at the plume front is expected for a historical plume. This laboratory-based study provided realistic plume pH profiles (consistent with that measured from borehole samples) and identified underlying mechanisms responsible for pH evolution. PMID:15046332

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

2004-03-01

232

Importance of closely spaced vertical sampling in delineating chemical and microbiological gradients in groundwater studies  

USGS Publications Warehouse

Vertical gradients of selected chemical constituents, bacterial populations, bacterial activity and electron acceptors were investigated for an unconfined aquifer contaminated with nitrate and organic compounds on Cape Cod, Massachusetts, U.S.A. Fifteen-port multilevel sampling devices (MLS's) were installed within the contaminant plume at the source of the contamination, and at 250 and 2100 m downgradient from the source. Depth profiles of specific conductance and dissolved oxygen at the downgradient sites exhibited vertical gradients that were both steep and inversely related. Narrow zones (2-4 m thick) of high N2O and NH4+ concentrations were also detected within the contaminant plume. A 27-fold change in bacterial abundance; a 35-fold change in frequency of dividing cells (FDC), an indicator of bacterial growth; a 23-fold change in 3H-glucose uptake, a measure of heterotrophic activity; and substantial changes in overall cell morphology were evident within a 9-m vertical interval at 250 m downgradient. The existence of these gradients argues for the need for closely spaced vertical sampling in groundwater studies because small differences in the vertical placement of a well screen can lead to incorrect conclusions about the chemical and microbiological processes within an aquifer.Vertical gradients of selected chemical constituents, bacterial populations, bacterial activity and electron acceptors were investigated for an unconfined aquifer contaminated with nitrate and organic compounds on Cape Cod, Massachusetts, USA. Fifteen-port multilevel sampling devices (MLS's) were installed within the contaminant plume at the source of the contamination, and at 250 and 2100 m downgradient from the source. Depth profiles of specific conductance and dissolved oxygen at the downgradient sites exhibited vertical gradients that were both steep and inversely related. Narrow zones (2-4 m thick) of high N2O and NH4+ concentrations were also detected within the contaminant plume. A 27-fold change in bacterial abundance; a 35-fold change in frequency of dividing cells (FDC), an indicator of bacterial growth; a 23-fold change in 3H-glucose uptake, a measure of heterotrophic activity; and substantial changes in overall cell morphology were evident within a 9-m vertical interval at 250 m downgradient. The existence of these gradients argues for the need for closely spaced vertical sampling in ground-water studies because small differences in the vertical placement of a well screen can lead to incorrect conclusions about the chemical and microbiological processes within an aquifer.

Smith, R. L.; Harvey, R. W.; LeBlanc, D. R.

1991-01-01

233

Bromine oxidation in volcanic plumes  

NASA Astrophysics Data System (ADS)

Volcanoes are very strong sources of hydrogen, carbon, sulphur and halogen compounds, as well as of particles. Some gases only behave as passive tracers; others interact and affect the formation, growth or chemical characteristics of aerosol particles in a complex system. Recent measurements of halogen radicals in volcanic plumes showed that volcanic plumes are chemically very active. Kinetic considerations (Oppenheimer et al., 2006) and detailed calculations with an atmospheric chemistry model (Bobrowski et al., 2007) explain the halogen chemistry mainly with photochemical reactions involving both, the gas and particle phase. They reproduce the measured gas-phase concentrations quite well. However, temporal evolution of BrO in the early plume is not well described in the models. The understanding of chemical kinetics of BrO formation is still not complete. Recent measurement results (Vogel et al., 2008) do not fit with initial model calculation. The new data lead to the suggestion that the BrO formation could be much faster during the first few minutes after emission than initially suggested. Old and recent data sets will be confronted, compared and possible causes of their differences discussed. The measurements considered were taken at Mt. Etna (Italy), Villarica (Chile), and Popocatépetl (Mexico) volcanoes. Additionally, at Mt Etna the emission consists of up to four individual plumes from four summit craters. The differences between the individual plumes have been investigated during the last years and will be presented.

Bobrowski, N.; Vogel, L.; Kern, C.; Giuffrida, G. B.; Delgado-Granados, H.; Platt, U.

2009-04-01

234

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

235

PERFORMANCE AND ANALYSIS OF AQUIFER TESTS WITH IMPLICATIONS FOR CONTAMINANT TRANSPORT MODELING  

EPA Science Inventory

The scale-dependence of dispersivity values used in contaminant transport models to estimate the spreading of contaminant plumes by hydrodynamic dispersion processes was investigated and found to be an artifact of conventional modeling approaches (especially, vertically averaged ...

236

Calculation of river-seawater endmembers and differential trace metal scavenging in the Columbia River plume  

NASA Astrophysics Data System (ADS)

A simple model is presented for calculating river and seawater mixing zone endmembers. This model allows construction of a conservative mixing line with respect to trace metals scavenged from surface waters, in the absence of direct endmember sampling. Results of the model suggest a transition from non-conservative to conservative behavior of the trace metals gallium (Ga) and zirconium (Zr) along a transect extending offshore of the Columbia River, indicating environmental controls on differential scavenging. Mechanistic explanation of observed differential scavenging is supported by wind data indicating northward transport of Columbia River plume waters, followed by southwest, offshore, transport. Columbia River plume waters transported to the southwest at the time of sample collection were therefore flanked offshore by aged plume waters returning from the north. While upwelling conditions provide nutrients during southerly transport of plume waters, northward plume transport is associated with downwelling, low nutrient conditions. Low phytoplankton abundance during periods of northward plume transport reduces trace metal scavenging, therefore dilution of river waters with ocean surface waters of comparatively low Ga and Zr concentrations results in near-conservative mixing of Ga and Zr in offshore, aged, plume waters. Results of this work suggest dynamic modification of trace metal residence time within close geographic proximity established by physical and biologic controls, dictated by local winds. Lower trace metal scavenging rates, resulting in a longer residence time, are suggested during northward transport of Columbia River plume waters, compared to higher scavenging rates, and thus shorter residence times, during southerly transport of plume waters. Gallium, demonstrating high analytical precision, reduced contamination risk, and decreased complications of upwelled sources relative to Zr, is proposed to provide identification of aged Columbia River plume waters.

McAlister, Jason; Orians, Kristin

2012-03-01

237

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

238

Delineation, characterization, and classification of topographic eminences  

NASA Astrophysics Data System (ADS)

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

Sinha, Gaurav

239

Modeling Leaking Gas Plume Migration  

SciTech Connect

In this study, we obtain simple estimates of 1-D plume propagation velocity taking into account the density and viscosity contrast between CO{sub 2} and brine. Application of the Buckley-Leverett model to describe buoyancy-driven countercurrent flow of two immiscible phases leads to a transparent theory predicting the evolution of the plume. We obtain that the plume does not migrate upward like a gas bubble in bulk water. Rather, it stretches upward until it reaches a seal or until the fluids become immobile. A simple formula requiring no complex numerical calculations describes the velocity of plume propagation. This solution is a simplification of a more comprehensive theory of countercurrent plume migration that does not lend itself to a simple analytical solution (Silin et al., 2006). The range of applicability of the simplified solution is assessed and provided. This work is motivated by the growing interest in injecting carbon dioxide into deep geological formations as a means of avoiding its atmospheric emissions and consequent global warming. One of the potential problems associated with the geologic method of sequestration is leakage of CO{sub 2} from the underground storage reservoir into sources of drinking water. Ideally, the injected green-house gases will stay in the injection zone for a geologically long time and eventually will dissolve in the formation brine and remain trapped by mineralization. However, naturally present or inadvertently created conduits in the cap rock may result in a gas leak from primary storage. Even in supercritical state, the carbon dioxide viscosity and density are lower than those of the indigenous formation brine. Therefore, buoyancy will tend to drive the CO{sub 2} upward unless it is trapped beneath a low permeability seal. Theoretical and experimental studies of buoyancy-driven supercritical CO{sub 2} flow, including estimation of time scales associated with plume evolution, are critical for developing technology, monitoring policy, and regulations for carbon dioxide geologic sequestration protecting the sources of potable water.

Silin, Dmitriy; Patzek, Tad; Benson, Sally M.

2007-08-20

240

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.

241

Delineating method employing electron ray beam  

US Patent & Trademark Office Database

A proximity effect correction method used in a delineation method employing an electron ray beam, in which the electron ray beam is illuminated on an electron ray sensitive resist material for delineating a pattern on the resist material. The method consists in dividing the pattern for delineation into pre-set unitary domains, and correcting the exposure light volume of an electron ray beam illuminated on each unitary domain in consideration of the accumulated energy ascribable to backward scattering of electrons. The proximity effect correction method includes the steps of bit-map-developing each unitary domain and calculating a pattern areal density in each unitary domain, averaging the pattern areal density in each unitary domain for calculating the averaged pattern area density, calculating the gradient vector of the averaged pattern areal density, and extracting a unitary domain where the magnitude of the calculated gradient vector is more than a pre-set value for identifying the unitary domain exhibiting a high correction error in the proximity effect correction.

1999-08-03

242

The Ultraviolet Plume Instrument (UVPI)  

NASA Astrophysics Data System (ADS)

The Ultraviolet Plume Instrument (UVPI) was launched aboard the Low-power Atmospheric Compensation Experiment (LACE) satellite on 14 Feb. 1990. Both the spacecraft and the UVPI were sponsored by the Directed Energy Office of the Strategic Defense Initiative Organization. The mission of the UVPI was to obtain radiometrically calibrated images of rocket plumes at high altitude and background image data of the Earth, Earth's limb, and celestial objects in the near- and middle-UV wave bands. The UVPI was designed for nighttime observations, i.e., to acquire and track relatively bright objects against a dark background.

Horan, D. M.

243

Photographic Measurements of USAF Aircraft Plume Rise.  

National Technical Information Service (NTIS)

This report includes data and results which were obtained during plume rise experimentation. Aircraft plumes were photographed using the smoke-producing F-102 drones, and Thunderbird T-38 aircraft. The second set of experiments indicated that, under low w...

P. D. Music J. S. Hunt D. F. Naugle

1977-01-01

244

Experiments on a turbulent plume: Shape analyses  

Microsoft Academic Search

Shape change of turbulent plume after its ejection was studied from experimentsNew methods to characterize plume shape were devised to define 4 regimesFor the same Reynolds number regime onset times become earlier with buoyancy

Shogo Kitamura; Ikuro Sumita

2011-01-01

245

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

EPA Science Inventory

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

246

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

247

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

248

Plasma plume MHD power generator and method  

Microsoft Academic Search

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.

1993-01-01

249

Prediction of Minuteman Exhaust Plume Electrical Properties.  

National Technical Information Service (NTIS)

Results of a comprehensive investigation of Minuteman exhaust plume electrical properties are presented. Electron density and electron-neutral collision frequency profiles are given for the Stage 1 plume at 100 kft and the Stage 2 plume at 118,200 and 300...

H. S. Pergament R. R. Mikatarian

1973-01-01

250

K-2 Titan IV Stratospheric Plume Dispersion.  

National Technical Information Service (NTIS)

Video images were recorded of the plume from the K-2 Titan IV launched 2 July 1996 from Cape Canaveral Air Station. These images were used to infer plume motion and expansion near an altitude of 30 km in the stratosphere. The plume was observed to move ac...

E. J. Beiting R. A. Klingberg

1997-01-01

251

Structure and dynamics of sheared mantle plumes  

Microsoft Academic Search

An extensive series of laboratory experiments is used to investigate the behavior of sheared thermal plumes. The plumes are generated by heating a small circular plate on the base of a cylindrical tank filled with viscous fluid and then sheared by rotating a horizontal lid at the fluid surface. The motion of passive tracers in the plumes is visualized by

Ross C. Kerr; Catherine Mériaux

2004-01-01

252

Radiation from advanced solid rocket motor plumes  

Microsoft Academic Search

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

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

1994-01-01

253

The Rise of Moist, Buoyant Plumes  

Microsoft Academic Search

The governing equations for a moist, buoyant plume in a cross wind are presented. A comparison of the energy equations for saturated and unsaturated plumes, the subject of some previous controversy, shows that the form of the two equations is identical only when the saturated plume is in a saturated atmosphere. In this case, the moist adiabatic lapse rate replaces

Jeffrey C. Weil

1974-01-01

254

Laboratory investigation of a single mantle plume  

Microsoft Academic Search

Although many have studied the chemistry and dynamics of mantle plumes, fundamental questions remain. These can be grouped into two general issues: a) Plume structure and dynamical interaction with the surrounding mantle, b) The degree of entrainment and mixing in mantle plumes of chemically distinct material from the deep mantle. We address these fundamental questions by performing detailed fluid dynamical

Aline Cotel

2005-01-01

255

Numerical Simulations of Europa Hydrothermal Plumes  

Microsoft Academic Search

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

J. C. Goodman; E. Lenferink

2009-01-01

256

Ridge suction drives plume-ridge interactions  

Microsoft Academic Search

Deep-sourced mantle plumes, if existing, are genetically independent of plate tectonics. When the ascending plumes approach lithospheric plates, interactions between the two occur. Such interactions are most prominent near ocean ridges where the lithosphere is thin and the effect of plumes is best revealed. While ocean ridges are mostly passive features in terms of plate tectonics, they play an active

Y. Niu; R. Hékinian

2003-01-01

257

MATHEMATICAL MODEL FOR MULTIPLE COOLING TOWER PLUMES  

EPA Science Inventory

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

258

Fractal travel time estimates for dispersive contaminants.  

PubMed

Alternative fractional models of contaminant transport lead to a new travel time formula for arbitrary concentration levels. For an evolving contaminant plume in a highly heterogeneous aquifer, the new formula predicts much earlier arrival at low concentrations. Travel times of contaminant fronts and plumes are often obtained from Darcy's law calculations using estimates of average pore velocities. These estimates only provide information about the travel time of the average concentration (or peak, for contaminant pulses). Recently, it has been shown that finding the travel times of arbitrary concentration levels is a straightforward process, and equations were developed for other portions of the breakthrough curve for a nonreactive contaminant. In this paper, we generalize those equations to include alternative fractional models of contaminant transport. PMID:15882331

Clarke, Danelle D; Meerschaert, Mark M; Wheatcraft, Stephen W

259

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

SciTech Connect

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

Not Available

1991-10-01

260

Modeling Leaking Gas Plume Migration.  

National Technical Information Service (NTIS)

In this study, we obtain simple estimates of 1-D plume propagation velocity taking into account the density and viscosity contrast between CO(sub 2) and brine. Application of the Buckley-Leverett model to describe buoyancy-driven countercurrent flow of tw...

D. Silin S. M. Benson T. Patzek

2007-01-01

261

Near Field of Starting Plumes  

Microsoft Academic Search

Although steady jets and plumes have been studied extensively in the past, there is relatively little known about the initial stages of starting buoyant jets. The present investigation examined buoyancy-driven flows resulting from cylindrical containers w ith length to diameter ratios (L\\/D) between 2 and 13. Density ratios up to ten percent were utilized. A technique was developed to release

H. Johari; M. Gharib; D. Dabiri

1997-01-01

262

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

263

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

2011-08-10

264

Plasma Outflows Within Polar Coronal Plumes  

NASA Astrophysics Data System (ADS)

Plasma outflow velocities within polar coronal plumes and their contribution to the fast solar wind are a matter of controversy. We investigate the plasma dynamics within plumes through the analysis of high cadence and spatial resolution observations from the Solar Dynamic Observatory (SDO) jointly with STEREO and Hinode data. This analysis allows us to address the source of heating and plasma acceleration inside polar plumes and therefore obtain constraint on the contribution of plumes to the fast solar wind. Our results provide important constraints of theoretical model dealing with the formation and evolution of polar coronal plumes.

Raouafi, N.; Stenborg, G.; Vourlidas, A.

2011-12-01

265

Plasma plume MHD power generator and method  

DOEpatents

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

Hammer, James H. (Livermore, CA)

1993-01-01

266

Mixing-controlled biodegradation in a toluene plume--results from two-dimensional laboratory experiments.  

PubMed

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 electron-acceptors mix. Herein, we aim to test whether this hypothesis can be verified by experimental results obtained from aerobic and anaerobic degradation experiments in two-dimensional sediment microcosms. Toluene was selected as a model compound for oxidizable contaminants. The two-dimensional microcosm was filled with quartz sand and operated under controlled flow conditions simulating a contaminant plume in otherwise uncontaminated groundwater. Aerobic degradation of toluene by Pseudomonas putida mt-2 reduced a continuous 8.7 mg L(-1) toluene concentration by 35% over a transport distance of 78 cm in 15.5 h. In comparison, under similar conditions Aromatoleum aromaticum strain EbN1 degraded 98% of the toluene infiltrated using nitrate (68.5+/-6.2 mg L(-1)) as electron acceptor. A major part of the biodegradation activity was located at the plume fringes and the slope of the electron-acceptor gradient was steeper during periods of active biodegradation. The distribution of toluene and the significant overlap of nitrate at the plume's fringe indicate that biokinetic and/or microscale transport processes may constitute additional limiting factors. Experimental data is corroborated with results from a reactive transport model using double Monod kinetics. The outcome of the study shows that in order to simulate degradation in contaminant plumes, detailed data sets are required to test the applicability of models. These will have to deal with the incorporation of existing parameters coding for substrate conversion kinetics and microbial growth. PMID:18083271

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

2007-11-17

267

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

268

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...

269

Radiocarbon speciation and distribution in an aquifer plume and groundwater discharge area, Chalk River, Ontario  

Microsoft Academic Search

The storage of low level radioactive waste in trenches overlying an unconfined groundwater flow system in sands has generated a contaminant plume (with chemical characteristics of dilute sanitary landfill leachate) containing 14C both as dissolved inorganic and organic C. In the groundwater, dissolved organic compounds account, on average, for 22% of the total C and 10% of the 14C. Approximately

R. W. D. Killey; R. R. Rao; S. Eyvindson

1998-01-01

270

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

2008-05-17

271

Rapid characterization of a chromium\\/trichloroethene plume using several real-time sampling and analysis technologies  

Microsoft Academic Search

An industrial facility located in the midwestern US began chrome-plating and degrading operations in 1941. Ground water contamination was recognized in August 1993. The extent of TCE plume was found to be approximately 5,000 feet long, 400 feet wide, and 70 feet thick. The chromium plume was much narrower (approximately 100 feet) and shorter (less than 3,000 feet). Ground water

Rehm

1995-01-01

272

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

273

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

NASA Astrophysics Data System (ADS)

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 °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 °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.

van Stempvoort, Dale R.; Armstrong, James; Mayer, Bernhard

2007-07-01

274

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

2007-01-13

275

Enhanced biodegradation by hydraulic heterogeneities in petroleum hydrocarbon plumes.  

PubMed

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

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

2008-11-17

276

Geochemical Evidence for Mantle Plume Involvement in the Early History of the Central Atlantic Ocean  

NASA Astrophysics Data System (ADS)

Controversy surrounds the issue of whether mantle plume activity was responsible for Pangean continental rifting and massive flood volcanism (resulting in the Central Atlantic Magmatic Province or CAMP, emplaced around 200 Ma) preceding the opening of the central Atlantic Ocean in the Early Mesozoic. Our new Sr-Nd-Pb isotopic and trace element data for the oldest basalts sampled from central Atlantic oceanic crust by deep-sea drilling show that oceanic crust generated from about 160 to 120 Ma displays clear isotopic and chemical signals of plume contamination (e.g., 87Sr/86Sri = 0.7032 to 0.7036, ? Nd(t) = +6.2 to +8.2, incompatible element patterns with positive Nb anomalies), but these signals are muted or absent in crust generated between 120 and 80 Ma, which resembles young Atlantic normal mid-ocean ridge basalt (N-MORB). The plume-affected pre-120 Ma Atlantic crust samples are isotopically similar to lavas from the Ontong Java Plateau, and may represent one isotopic end-member for CAMP basalts. The strongest plume signature is displayed near the center of CAMP magmatism but the hotspots currently nearest this location in the mantle reference frame appear younger than Cretaceous age and are isotopically distinct from the oldest Atlantic crust. The evidence for widespread plume contamination of the nascent Atlantic upper mantle, combined with a lack of evidence for a long-lived volcanic chain associated with this plume, leads us to propose that the enriched signature of early Atlantic crust, and possibly the eruption of the CAMP, were caused by a relatively short-lived, but large volume plume feature that was not rooted at a mantle boundary layer. Such a phenomenon has been predicted by recent numerical models of mantle circulation (Cserepes and Yuen, EPSL 183, 2000).

Janney, P. E.; Castillo, P. R.

2001-12-01

277

PROPOSED PRAGMATIC METHODS FOR ESTIMATING PLUME RISE AND PLUME PENETRATION THROUGH ATMOSPHERIC LAYERS  

EPA Science Inventory

Methods are proposed for estimating plume rise taking advantage of data on the vertical variation of wind speed and temperature. In addition, partial penetration of the plume into the stable layer above the mixing height is considered....

278

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

279

Erosion plume dynamics during pulsed laser alloying  

Microsoft Academic Search

Dynamics of erosion plume during pulsed laser alloying (? = 1.06 ?m, pulse duration in millisecond range, power density 105–106 W\\/cm2) of Fe with Mo, Al, Sn was analysed by means of high speed photorecording. Two qualitatively different types of plume dynamics were found: cylindrical vapour helixes and periodic pulsation. The monitoring of plume dynamics and melt ejection allows one

V. Titov; I. Smurov; M. Ignatiev

1996-01-01

280

Mantle plumes control magnetic reversal frequency  

Microsoft Academic Search

A sequence of events is adduced to prove the contention that mantle plumes control magnetic reversal frequency. Mantle plumes rise from the D-arcsec seismic layer just above the core\\/mantle boundary, thinning D arcsec to fuel the plumes. This increases core cooling by allowing heat to be conducted more rapidly across the core\\/mantle boundary. Outer core convective activity increases to restore

Roger L. Larson; Peter Olson

1991-01-01

281

Virtual origin correction for lazy turbulent plumes  

NASA Astrophysics Data System (ADS)

The location of the virtual origin of positively buoyant forced plumes with a deficit of momentum compared with equivalent pure plumes is considered. These lazy plumes, generated by steady releases of momentum, buoyancy and volume from sources (at z = 0) of finite area into a quiescent uniform ambient, are shown to be equivalent to pure plumes issuing from a point source at the virtual origin z = -z_avs located below the actual source. An analytic expression for the location of the virtual origin relative to the actual source is developed. Our analysis provides a physically realistic correction and differs from Morton’s (1959) analysis where the flow from the actual source is related to that from a point source with modified initial momentum flux directed downwards from a point above the physical source. The displacement zavs of the virtual origin from the actual source depends on the relative importance of the initial fluxes of buoyancy , momentum and volume as characterised by the parameter . The correction developed is valid for ? > 1/2 and is applicable, therefore, to lazy plumes (? > 1), pure plumes (? = 1), and forced plumes in the range 1/2 < ? < 1. As ? increases z_avs decreases and for ? >> 1, . Comparisons between the theory and measurements of lazy saline plumes show close agreement. MORTON, B. R. 1959 Forced plumes J. Fluid Mech. 5, 151--163.

Hunt, Gary; Kaye, Nigel

1999-11-01

282

Virtual origin correction for lazy turbulent plumes  

NASA Astrophysics Data System (ADS)

The location of the asymptotic virtual origin of positively buoyant turbulent plumes with a deficit of initial momentum flux when compared with equivalent pure plumes is investigated. These lazy plumes are generated by continuous steady releases of momentum, buoyancy and volume into a quiescent uniform environment from horizontal sources (at z = 0) of finite area, and are shown to be equivalent to the far-field flow above point source pure plumes, of buoyancy only, rising from the asymptotic virtual source located below the actual source at z = [minus sign]zavs.

Hunt, G. R.; Kaye, N. G.

2001-05-01

283

SOHO CDS observations of coronal hole plumes  

NASA Astrophysics Data System (ADS)

Coronal Diagnostic Spectrometer (CDS) observations of a polar coronal hole plume are presented. Spectroscopic diagnostic techniques are applied to characterise the plume in terms of density, temperature, emission measure and elemental abundance. It is found that polar plume bases exhibit the same characteristics as the Elephant's Trunk equatorial plume, i.e. are nearly isothermal with temperatures =~ 8 x 105 K, have densities Nlo {e} =~ 1.2 x 109 cm-3, and do not have a significant FIP effect, contrary to what has long been thought.

Del Zanna, G.

284

Recognizing Mantle Plumes in the Geological Record  

NASA Astrophysics Data System (ADS)

Mantle plumes are recognized by domal uplift, triple junction rifting, and especially the presence of a large igneous province (LIP), dominated in the Phanerozoic by flood basalts, and in the Proterozoic by the exposed plumbing system of dykes, sills, and layered intrusions. In the Archean, greenstone belts that contain komatiites have been linked to plumes. In addition, some carbonatites and kimberlites may originate from plumes that have stalled beneath thick lithosphere. Geochemistry and isotopes can be used to test and characterize the plume origin of LIPs. Seismic tomography and geochemistry of crustal and subcrustal xenoliths in kimberlites can identify fossil plumes. More speculatively, plumes (or clusters of plumes) have been linked with variation in the isotopic composition of marine carbonates, sea-level rise, iron formations, anoxia events, extinctions, continental breakup, juvenile crust production, magnetic superchrons, and meteorite impacts. The central region of a plume is located using the focus of a radiating dyke swarm, the distribution of komatiites and picrites, etc. The outer boundary of a plume head circumscribes the main flood basalt distribution and approximately coincides with the edge of domal uplift that causes shoaling and offlap in regional sedimentation.

Ernst, Richard E.

285

Wellhead protection area delineation under uncertainty  

SciTech Connect

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). Goal of the State Wellhead Protection (WHP) Program is to ``protect wellhead areas within their jurisdiction from contaminants which may have any adverse effect on the health of persons.`` A major component of WHP is the determination of zones around water-supply wells called Wellhead Protection Areas (WHPAs) within which contaminant source assessment and management should be addressed. WHPAs are defined in the SDWA as ``the surface and subsurface area surrounding a water well or wellfield, supplying a public water system, through which contaminants are reasonably likely to move toward and reach such water well or wellfield.`` A total of 14 water-supply wells are currently being used at the Nevada Test Site (NTS). Eleven of the wells are used for potable water supplies and the remaining three wells are used for construction purposes only. Purpose of this study is to estimate WHPAs for each water-supply well at the NTS. Due to the limited information about the hydraulic properties needed for estimating the WHPAS, an approach that considered the uncertainty in the estimates of the hydraulic properties was developed and implemented.

Jacobson, E.; Andricevic, R.; Hultin, T.

1994-09-01

286

Numerical experiments and field results on the size of steady state plumes.  

PubMed

Contaminated groundwater poses a serious risk for drinking water supplies. Under certain conditions, however, groundwater contamination remains restricted to a tolerable extent because of natural attenuation processes. We present an innovative approach to evaluate the size of these so-called steady-state plumes by 2-D and 1-D modelling in homogeneous aquifers. If longitudinal mixing is negligible, scenarios can be modelled in a simplified way using a 1-D domain vertical to the direction of flow. We analysed the sensitivity of the plume length with respect to biodegradation kinetics, flow velocity, transverse vertical dispersivity alphat, the source and aquifer geometry and reaction stoichiometry. Our findings indicate that for many readily biodegradable compounds transverse-dispersive mixing rather than reaction kinetics is the limiting factor for natural attenuation. Therefore, if alphat, aquifer and source geometry and concentrations of electron acceptors and donors are known, the length of the steady state contaminant plume can be predicted. The approach is validated under field conditions for an ammonium plume at a former landfill site in SW Germany. PMID:16500721

Maier, U; Grathwohl, P

2006-02-28

287

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

SciTech Connect

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

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

2011-11-01

288

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

SciTech Connect

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

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

1999-03-01

289

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...

290

Statistical Assessment of Unidirectional Propagation of a Leachate Contamination Plume  

Microsoft Academic Search

The leachate produced by the Municipal Solid Waste Landfill of São Pedro da Aldeia (State of Rio de Janeiro, Brazil) flows\\u000a almost entirely in one direction guided by a natural ditch in the bottom of a gentle valley. This landfill has been in operation\\u000a with no concern to environmental protection, such as containment systems or leachate drainage and treatment. This

M. Pacheco; N. Sivakugan; M. C. Barbosa

2009-01-01

291

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. ...

292

Surface and Borehole Electromagnetic Imaging of Conducting Contaminant Plumes  

Microsoft Academic Search

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

Berryman; James G

2000-01-01

293

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

294

Contaminant Plume Monitoring Adjacent to the Kesterson Reservoir, California.  

National Technical Information Service (NTIS)

Detailed ground conductivity surveys have been made twice with the Geonics EM31 and EM34 systems over a 2 km(sup 2) area adjacent to Ponds 1, 2 and 5 of the Kesterson Reservoir. In spite of relatively high and variable near-surface conductivities, the fir...

N. E. Goldstein S. L. Pillsbury J. S. Daggett S. M. Benson

1989-01-01

295

Motion of Pacific mantle plumes  

NASA Astrophysics Data System (ADS)

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

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

2007-12-01

296

Redox conditions for mantle plumes  

NASA Astrophysics Data System (ADS)

The vanadium to scandium ratio (V/Sc) for basalts from mid-ocean ridge (MOR) and arc environments has been proposed as a proxy for fO2 conditions during partial melting (e.g. [1] and [2]). Contrary to barometric measurements of the fO2 of primitive lavas, the V/Sc ratio of the upper mantle at mid-ocean ridges and arcs is similar, leading previous authors to propose that the upper mantle has uniform redox potential and is well-buffered. We have attempted to broaden the applicability of the V/Sc parameter to plume-influenced localities (both oceanic and continental), where mantle heterogeneities associated with recycled sediments, mafic crust, and metasomatized mantle, whether of shallow or deep origin, exist. We find that primitive basalts from the North Atlantic Igneous Province (NAIP), Hawaii (both the Loa and Kea trends), Deccan, Columbia River, and Siberian Traps show a range of V/Sc ratios that are generally higher (average ~9) than those for MOR (average ~ 6.7) or arc (average ~7) lavas. Based on forward polybaric decompression modeling, we attribute these differences to polybaric melting and melt segregation within the garnet stability field rather than the presence of a more oxidized mantle in plume-influenced settings. Like MORB, the V/Sc ratios for plume-influenced basalts can be accounted for by an oxidation state approximately one log unit below the Ni-NiO buffer (NNO-1). Our analysis suggests that source heterogeneities have little, if any, resolvable influence on mantle redox conditions, although they have significant influence on the trace element and isotopic composition of mantle-derived melts. We suggest that variations in the redox of erupted lavas is largely a function of shallow lithospheric processes rather than intrinsic to the mantle source, regardless of tectonic setting. [1] Li and Lee (2004) EPSL, [2] Lee et al. (2005) J. of Petrology

Heister, L. E.; Lesher, C. E.

2005-12-01

297

Volcanic Plume Chemistry: Models, Observations and Impacts  

NASA Astrophysics Data System (ADS)

Volcanic plumes are highly chemically reactive; both in the hot, near-vent plume, and also at ambient temperatures in the downwind plume, as the volcanic gases and aerosol disperse into the background atmosphere. In particular, DOAS (Differential Optical Absortpion Spectroscopy) observations have identified BrO (Bromine Monoxide) in several volcanic plumes degassing into the troposphere. These observations are explained by rapid in-plume autocatalytic BrO-chemistry that occurs whilst the plume disperses, enabling oxidants such as ozone from background air to mix with the acid gases and aerosol. Computer modelling tools have recently been developed to interpret the observed BrO and predict that substantial ozone depletion occurs downwind. Alongside these modelling developments, advances in in-situ and remote sensing techniques have also improved our observational understanding of volcanic plumes. We present simulations using the model, PlumeChem, that predict the spatial distribution of gases in volcanic plumes, including formation of reactive halogens BrO, ClO and OClO that are enhanced nearer the plume edges, and depletion of ozone within the plume core. The simulations also show that in-plume chemistry rapidly converts NOx into nitric acid, providing a mechanism to explain observed elevated in-plume HNO3. This highlights the importance of coupled BrO-NOx chemistry, both for BrO-formation and as a production mechanism for HNO3 in BrO-influenced regions of the atmosphere. Studies of coupled halogen-H2S-chemistry are consistent with in-situ Alphasense electrochemical sensor observations of H2S at a range of volcanoes, and only predict H2S-depletion if Cl is additionally elevated. Initial studies regarding the transformations of mercury within volcanic plumes suggest that significant in-plume conversion of Hg0 to Hg2+ can occur in the downwind plume. Such Hg2+ may impact downwind ecology through enhanced Hg-deposition, and causing enhanced biological uptake of mercury. Excitingly, we can now begin to compare the model simulations to very recently reported in-situ aircraft and balloon measurements in downwind volcanic plumes, which found e.g. ozone depletion at Redoubt, ozone depletion and elevated HNO3 at Erebus and sulfate-H2O interactions at Kilauea. Satellite observations of volcanic BrO, and DOAS observations of BrO under varying plume conditions have also recently been reported. Such comparisons may highlight additional chemistry (e.g. HO2NO2 at Erebus), identify further underlying processes (e.g. the role of plume dispersion and gas fluxes in controlling plume chemistry), guide future field-observation strategies, and support and improve the model simulations that aim to understand volcanic emissions, plume chemistry, and predict the environmental impacts of volcanic plumes.

Roberts, Tjarda; Martin, Robert; Oppenheimer, Clive; Griffiths, Paul; Braban, Christine; Cox, Tony; Jones, Rod; Durant, Adam; Kelly, Peter

2010-05-01

298

The MISR Wildfire Smoke Plume Height Project  

NASA Astrophysics Data System (ADS)

Together the Multi-angle Imaging SpectroRadiometer (MISR) and the Moderate Resolution Imaging Spectoradiometer (MODIS) instruments on the Terra satellite observe several characteristics of wildfire smoke plumes. With support from NASA and the EPA, the MISR team is assembling a database of these observations for North America, Africa, Siberia, Indonesia, etc. that extends back to the beginning of the Terra mission in 2000. The thermal infrared channels on MODIS provide the location of fires and their approximate radiative power. By using an interactive visualization program called the MISR INteractive eXplorer (MINX), users interactively digitize wildfire plumes to retrieve accurate plume heights and wind speeds using a new stereo height retrieval algorithm. This information, along with the locations and directions of individual plumes, their areas and aerosol properties derived from the operational MISR aerosol algorithm, are stored in this publicly accessible database for subsequent analysis (http://www-misr2.jpl.nasa.gov/EPA-Plumes/). The plume database currently contains about 4000 smoke plumes and smoke clouds from North America. An equal number of plumes and clouds for other regions around the world has also been digitized. A few thousand additional plumes are in the process of being incorporated. Smoke plumes in this context are considered to be discrete regions of smoke that can be followed to their fire sources at ground level and have a distinctive shape determined by the direction the smoke is driven downwind. Smoke “clouds” are defined here as regions of dense smoke not clearly associated with specific fire sources, and whose direction of transport is not easily determined. Plume height measurements can be used as a surrogate for injection heights, which are important for modeling smoke transport. Examples of height and wind retrievals for specific plumes will be shown. Those chosen have not only been incorporated in statistical analyses of plume heights, but the quality of their spatial height variations is such that they are useful in dynamic modeling of plume rise. Both the plume database and the MINX program will be described.

Nelson, D. L.; Garay, M. J.; Diner, D. J.; Kahn, R. A.

2010-12-01

299

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

300

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

301

Designing optimal strategies for contaminated groundwater remediation  

NASA Astrophysics Data System (ADS)

The problem of locating pumps and setting pump rates to most effectively stabilize and remove a plume of contaminated groundwater at a hazardous waste site is examined. Nonlinear optimization methods are combined with convective-disperisve transport simulation in a unit response matrix type of optimization formulation. Constraints are used which guarantee that the contaminant plume is removed by limiting the concentrations at nodal points in the domain at a future time. Additional constraints explicitly require that concentrations not increase in the area outside the initial plume boundary. The effectiveness of alternative formulations are examined by performing numerical experiments using a hypothetical aquifer. The experiments show that computational costs are dominated by the repeated simulations required for computation of constraint gradients and are proportional to the number of pump sites under consideration. This characteristic of the formulation and algorithm used, limits the use of the approach to problems where the number of potential pump sites is relatively small.

Ahlfeld, David P.; Mulvey, John M.; Pinder, George F.

302

Application of 4D resistivity image profiling to detect DNAPLs plume.  

NASA Astrophysics Data System (ADS)

In July 1993, the soil and groundwater of the factory of Taiwan , Miaoli was found to be contaminated by dichloroethane, chlorobenzene and other hazardous solvents. The contaminants were termed to be dense non-aqueous phase liquids (DNAPLs). The contaminated site was neglected for the following years until May 1998, the Environment Protection Agency of Miaoli ordered the company immediately take an action for treatment of the contaminated site. Excavating and exposing the contaminated soil was done at the previous waste DNAPL dumped area. In addition, more than 53 wells were drilled around the pool with a maximum depth of 12 m where a clayey layer was found. Continuous pumping the groundwater and monitoring the concentration of residual DNAPL contained in the well water samples have done in different stages of remediation. However, it is suspected that the DNAPL has existed for a long time, therefore the contaminants might dilute but remnants of a DNAPL plume that are toxic to humans still remain in the soil and migrate to deeper aquifers. A former contaminated site was investigated using the 2D, 3D and 4D resisitivity image technique, with aims of determining buried contaminant geometry. This paper emphasizes the use of resistivity image profiling (RIP) method to map the limit of this DNAPL waste disposal site where the records of operations are not variations. A significant change in resistivity values was detected between known polluted and non-polluted subsurface; a high resistivity value implies that the subsurface was contaminated by DNAPL plume. The results of the survey serve to provide insight into the sensitivity of RIP method for detecting DNAPL plumes within the shallow subsurface, and help to provide valuable information related to monitoring the possible migration path of DNAPL plume in the past. According to the formerly studies in this site, affiliation by excavates with pumps water remediation had very long time, Therefore this research was used iron nanoparticles with pumps water remediation ways. The survey lines use the same length and the same position of the different time observation. The survey lines monitors the iron nanoparticles and pollution flow direction with remediation effect. By used the iron nanoparticles and pumping water remediation ways, the DNAPL plumes had eminent changed. Iron nanoparticles granule is smaller than the micron iron, Therefore the reaction rate was quite quick at the iron nanoparticles and pumps, but the ferric oxide can cause the electronic resistivity to elevate produces after the response. Pumps water rectifies may remove the ferric oxide to cause the electronic resistivity to reduce. The iron nanoparticles and pollution response is extremely obviously of the Resistivity Image Profile.

Liu, H.; Yang, C.; Tsai, Y.

2008-12-01

303

Characteristics and scaling of bubble plumes from marine hydrocarbon seepage in the Coal Oil Point seep field  

NASA Astrophysics Data System (ADS)

The fate of marine seep gases in the ocean and atmosphere is intimately connected with bubble and bubble-plume processes, which are strongly size- and depth-dependent. Size-dependent flux distributions, ?, and vertical velocity functions, VZ(r), were measured with a video bubble measurement system in the Santa Barbara Channel, California. Several distinct plume types were identified for which size distributions were measured, major, minor, intermediate, and obstructed. A further vent class is elastic (which was observed but not quantified). In addition, any plume class could be oily. Minor plumes generally produced a lower emission flux, Q, and showed narrow, peaked ? that were well described as Gaussian. The radius of the dominant peak, RP, of minor plumes varied as Q0.40, with correlation coefficient, R2 = 0.84, in agreement with theoretical relationship of RP˜Q0.4 for Q above a critical flow rate. Oil contamination was found to affect RP and was not used in the fit. A probability distribution, ?(RP), for all Gaussian bubble plumes was itself well described by a combination of Gaussian functions, which were different for different seep areas. Major plumes showed a broad distribution including very small and very large bubbles and were well described by a power law with exponent a, which varied with Q according to a = 0.43 + 0.55 log(Q) with R2 = 0.77. One obstructed vent was analyzed and shared characteristics with the minor bubble plumes. Mixed bubble plume size distributions showed characteristics of both major and minor plume classes, i.e., were described by a combination of Gaussian functions and power laws, and were steeper (higher a) than major plumes for the same Q. Oily plumes produced complex, confused bubble size distributions. Upwelling velocities, VUP(r), were derived from VZ(r) and increased as VUP˜Q0.66 (R2 = 0.64); however, consideration of the more intense plumes (Q > 2 cm s-1) showed VUP˜Q0.35 in agreement with other published field measurements. Thus, the weaker bubble plumes were observed during the acceleration phase.

Leifer, Ira

2010-11-01

304

Plasma plume MHD power generator and method  

Microsoft Academic Search

Highly-conducting plasma plumes are ejected across the interplanetary magnetic field from a situs that is moving relative to the solar wind, such as a spacecraft or an astral body, such as the moon, having no magnetosphere that excludes the solar wind. Discrete plasma plumes are generated by plasma guns at the situs extending in opposite directions to one another and

James H

1993-01-01

305

A Plume Rise Model Compared with Observations  

Microsoft Academic Search

Dimensional arguments are used to predict plume rise for buoyant plumes in both stable and neutral air, for both calm and windy conditions. Dominant terms are assumed to be windpseed ?, “buoyancy flux” F (proportional to heat efflux), and a stability parameter s (proportional to potential temperature gradient). Observations presented support the dimensional analysis predictions, except that for final rise

Gary A. Briggs

1965-01-01

306

Endothermic and exothermic chemically reacting plumes  

Microsoft Academic Search

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

Devin T. Conroy; Stefan G. Llewellyn Smith

2008-01-01

307

Detection of Gaseous Plumes using Basis Vectors  

Microsoft Academic Search

Detecting and identifying weak gaseous plumes using thermal imaging data is complicated by many factors. There are several methods currently being used to detect plumes. They can be grouped into two categories: those that use a chemical spectral library and those that dont. The approaches that use chemical libraries include least squares methods and physics-based approaches. They are \\

Lawrence Chilton; Stephen Walsh

2009-01-01

308

An experimental study of highly lazy plumes  

NASA Astrophysics Data System (ADS)

We present results from an experimental study of highly lazy turbulent plumes, i.e. plumes with relatively low source momentum flux, or equivalently very large source Richardson numbers. Experimental observations indicate that the plumes contract as they move vertically away from the source and that the extent of the contraction is independent of the source Richardson number (consistent with previous experimental studies). Using the experimental technique developed by Baines (1983), we made volume flux measurements in the near source region of the plume. Our experimental results indicate that the volume flux increases linearly with distance from the source and scales with the source Richardson number to the one third power. This result is discussed in relation to existing entrainment models for forced plumes (low source Richardson number) and we demonstrate that these do not adequately describe the near source region of highly lazy plumes. It is also noted that the near source behaviour is similar to that of a line plume and a possible explanation for this behaviour is presented. Baines, W.D. (1983), ``A technique for the direct measurement of volume flux of a plume,'' J. Fluid Mech. 132, 247--256.

Kaye, Nigel; Hunt, Gary

2006-11-01

309

Compression technique for plume hyperspectral images  

Microsoft Academic Search

The authors recently developed a hyperspectral image output option for a standardized government code designed to predict missile exhaust plume infrared signatures. Typical predictions cover the 2- to 5-m wavelength range (2000 to 5000 cm-1) at 5 cm-1 spectral resolution, and as a result the hyperspectral images have several hundred frequency channels. Several hundred hyperspectral plume images are needed to

B. K. Feather; S. A. Fulkerson; J. H. Jones; R. A. Reed; M. A. Simmons; D. G. Swann; W. E. Taylor; L. S. Bernstein

2005-01-01

310

The Structure of Round Buoyant Turbulent Plumes  

Microsoft Academic Search

An experimental and theoretical study of round buoyant turbulent plumes in still and unstratified environment was conducted, emphasizing self-preserving conditions. The experiments involved downward flowing round negatively -buoyant turbulent plumes created by injecting carbon dioxide and sulfur hexafluoride into still and unstratified air. The mixture fraction and velocity properties were measured using laser-induced iodine fluorescence (LIF) and laser -Doppler velocimetry

Zhongtao Dai

1995-01-01

311

Liquid Booster Module (LBM) Plume Flowfield Model.  

National Technical Information Service (NTIS)

A complete definition of the LBM plume is important for many Shuttle design criteria. The exhaust plume shape has a significant effect on the vehicle base pressure. The LBM definition is also important to the Shuttle base heating, aerodynamics and the inf...

S. D. Smith

1981-01-01

312

RECOGNIZING MANTLE PLUMES IN THE GEOLOGICAL RECORD  

Microsoft Academic Search

? Abstract Mantle plumes are recognized by domal uplift, triple junction rift- ing, and especially the presence of a large igneous province (LIP), dominated in the Phanerozoic by flood basalts, and in the Proterozoic by the exposed plumbing system of dykes, sills, and layered intrusions. In the Archean, greenstone belts that contain komatiites have been linked to plumes. In addition,

Richard E. Ernst; Kenneth L. Buchan

2003-01-01

313

MAGMA ACCUMULATION IN HAWAIIAN PLUME SOURCES  

Microsoft Academic Search

The steady state eruptions of Kilauea, Hawaii cannot be related to a percolative plume source, because continuous melt migration results in overly high overpressures in the upper part of the partially molten plume. The ascent of melt must instead be discontinuous. It is suggested that melt initially accumulates in conduits, and that melt episodically intrudes upward from one system of

SVEN MAALØE

314

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...

315

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...

316

Vestiges of the Kerguelen Plume in the Sylhet Traps, NE India: Reconstructing a 800km diameter plume head in the Bengal basin aligned with the Ninetyeast Ridge  

NASA Astrophysics Data System (ADS)

The 117Ma Sylhet Traps, exposed on the southern edge of the Shillong Plateau in northeastern India, are separated from the Rajmahal Traps ~550km to the west by the Gangetic-Brahmaputra alluvium of the Bengal basin. On the basis of the similar age of eruption, the Sylhet and Rajmahal Traps are correlated. We provide an isotope tracer study of the Sylhet Traps and relate them with the Rajmahal Traps, Kerguelen Plateau basalts and associated volcanic rocks in the Southern Indian Ocean, including the Ninetyeast Ridge. We report Nd-Sr-Pb-isotopic and multiple trace element data for 18 discrete and consecutive lava flows from two sections of the Sylhet Traps. Thirteen of these lavas are from the Cherrapunji-Shella (CH) Bazaar section and five from the Mawsynram-Balot (MB) section. In major, trace elements and Nd-Sr-Pb isotopes, most of the Sylhet lavas show similarity with the Rajmahal Traps, Bunbury basalts and lavas from the Naturaliste and parts of the Kerguelen Plateau. The combined geochemical data and their correlation with the Rajmahal Traps, Bunbury basalts, and some Kerguelen Plateau lavas, imply a relatively primitive Kerguelen plume source for the CH section basalts. We propose the average 117Ma composition of this plume source to be: ?Nd(I)=1.9, 87Sr/86Sr(I)=0.7046, with relatively flat rare earth element patterns, similar to the primitive mantle source for ODP sites 1138, 1141 and 1142 on the Kerguelen Plateau. The Nd-Sr-isotopic data for the Sylhet basalts are modeled with two end members, a ~18% partial melt of an uncontaminated plume member and a contaminant represented by the granulites of the Eastern Ghats Belt. Most of the Sylhet lavas are close to the proposed plume end-member, with less than 10% of the lithospheric granulite component. The contaminated Sylhet basalts reflect as much as 20% of the granulite component. We suggest the incorporation of the lower continental crustal contaminant in the Kerguelen plume-derived melt by thermal erosion. Combined Nd-Sr-Pb-isotopic evidence also reflects an absence of N-MORB and upper continental crustal components in these lavas. Collectively, these data in conjunction with alkalic and carbonatitic rocks associated with the Rajmahal-Sylhet tholeiites imply a zone of influence of the Kerguelen plume for ~800km in an east-west direction, linking this plume to its vestiges, the Rajmahal-Bengal-Sylhet Traps in northeastern India.

Basu, A. R.; Ghatak, A.

2010-12-01

317

Plasma dynamics in the polar coronal plumes  

NASA Astrophysics Data System (ADS)

We use the spectral shapes of the EUV line profiles to study the plasma dynamics, acceleration and heating, in polar plumes (PP). We find that the observed profiles are reproduced fairly well when considering low plume wind speeds and velocity turbulence (?_S) at low altitudes followed by a rapid acceleration and heating of the plasma to reach the properties of inter-plumes (IP) by ?3-4~R_?. We also find that plumes very close to the pole give narrow profiles at all heights that are not observed above ?2.5~R_?. This suggests a tendency for plume footpoints to lie more than 10° away from the pole. High resolution magnetograms of SOLIS and EUV images support this hypothesis.

Raouafi, N.-E.; Harvey, J. W.; Solanki, S. K.

318

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

319

Mount Everest snow plume: A case study  

NASA Astrophysics Data System (ADS)

A plume of snow blowing from the summit of Mount Everest is one of the most iconic images of the world's highest mountain. Its presence provides evidence of the strong jet stream winds that can buffet the mountain. In January 2004, astronauts onboard the International Space Station (ISS) observed a 15 to 20 km long snow plume emanating from the summit of Mount Everest. Remarkably little is known about these plumes and the role that they play in the redistribution of snow in the high Himalaya. In this paper we use a variety of meteorological datasets to show that the observed plume was the combination of high winds associated with the East Asian Jet Stream (EAJS) and a heavy snowfall that had occurred over the Himalaya during the preceding week. A simple model of a blown snow plume is shown to be consistent with the observations made from the ISS.

Moore, G. W. K.

2004-11-01

320

A TVD METHOD FOR CONTAMINANT TRANSPORT IN POROUS MEDIA  

Microsoft Academic Search

The objective of this work is to present a numerical study of contaminant migration in saturated porous media. For this purpose, the advection-difussion equation describing the evolution of contaminant plumes in a vertical cross section of an aquifer is discretized employing a Total Variation Diminishing method (TVD), which provides an efficient way to eliminate spurious numerical oscillations .The stationary velocity

Jacqueline Kohn; Juan E. Santos; Eduardo E. Kruse

1998-01-01

321

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

322

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

323

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

Microsoft Academic Search

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

P. Hunter; S. Naber; J. Verducci

1988-01-01

324

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

USGS Publications Warehouse

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

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

1991-01-01

325

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

Microsoft Academic Search

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

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

2008-01-01

326

Characterization of a Contaminant Inventory at DOE Sites, as a Tool for Selecting Monitoring and Remediation Technologies (Invited)  

NASA Astrophysics Data System (ADS)

The U.S. Department of Energy (DOE) is responsible for the remediation and long-term stewardship of one of the world’s largest groundwater contamination portfolios, with a significant number of plumes containing various contaminants, and considerable total mass and activity. The frequency of occurrence and ranking of contaminants in groundwater plumes is one of the main criteria needed for decision-making related to planning and prioritizing the types of basic research and the development of site characterization, monitoring, and remedial approaches. Using the data from 60 DOE sites, including 221 groundwater plumes, collected in the DOE Groundwater Database (GWD), we evaluated the frequency of occurrence of specific contaminants and their associations, plume volumes, contaminant maximum concentrations, masses, and isotope activities. Contaminants detected in groundwater at 60 DOE sites and facilities can be categorized into the following eight generic contaminant groups: chlorinated hydrocarbons (chlorinated ethenes), fuels and fuel components (i.e., petroleum/fuel hydrocarbons), explosives, metals, radioactive isotopes (excluding tritium), tritium, sulfates, and nitrates. The most common are plumes containing two (29.4% of all plumes in the GWD) and three (29%) contaminant groups. The most frequent binary combinations of contaminant groups are those of mixed waste, including chlorinated hydrocarbons and tritium—35% and metals and isotopes—28% of all plumes. Our results were compared to the data from 18 DOE sites and 91 plumes, collected in 1992, to illustrate the progress in site characterization and remediation over the past decade. The analysis of contaminant inventory and plume characteristics should be helpful in establishing priorities for basic research needs, which will enable cost-effective and efficient application of new characterization, monitoring, modeling, and remediation technologies.

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

2009-12-01

327

Groundwater plume control with phytotechnologies at Argonne National Laboratory.  

SciTech Connect

In 1999, Argonne National Laboratory-East (ANL-E) designed and installed a series of engineered plantings consisting of a vegetative cover system and approximately 800 hybrid poplars and willows rooting at various predetermined depths. The plants were installed using various methods including Applied Natural Science's TreeWell{reg_sign} system. The goal of the installation was to protect downgradient surface and groundwater by hydraulic control of the contaminated plume. This goal was to be accomplished by intercepting the contaminated groundwater with the tree roots, removing moisture from the upgradient soil area, reducing water infiltration, preventing soil erosion, degrading and/or transpiring the residual VOCs, and removing tritium from the subsoil and groundwater. The U.S. EPA Superfund Innovative Technology Evaluation Program (SITE) and ANL-E evaluated the demonstration. The effectiveness of the various plantings was monitored directly through groundwater measurements and samples, and indirectly via soil moisture probes, plant tissue analysis, microbial studies, geochemical analysis, and sap flow monitoring. A weather station with data logging equipment was installed. ANL-E modeled the predicted effect of the plants on the groundwater using MODFLOW. The demonstration has lasted three growing seasons and continues. This paper presents the results of the sampling, monitoring, and modeling efforts to date. The project was not only successful in reducing the groundwater contaminant flow and the contaminants at the source; it also provides insight into the techniques that are useful for measuring and predicting the effectiveness of future similar projects.

Rock, S.; Negri, M. C.; Quinn, J.; Wozniak, J.,; McPherson, J.

2002-07-16

328

Radiation from advanced solid rocket motor plumes  

NASA Astrophysics Data System (ADS)

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.

1994-12-01

329

Halogen and sulphur chemistry in volcanic plumes  

NASA Astrophysics Data System (ADS)

Bromine oxide has been measured in the plumes of several slowly erupting volcanoes. We compared field measurements from Mt. Etna, Italy with results from a one-dimensional model that was initialised with volcanic plume compositions according to a thermodynamic model. Assuming an "effective source region" where plume air is being mixed with ambient air at still high temperatures we were able to reproduce the measurements for BrO and SO2 very well (Bobrowski et al., 2007). The model resolves the vertical dilution of the plume and includes a parameterisation for the horizontal entrainment of background air as well as a detailed set of gas-phase and aqueous-phase reactions. We will show details of the chemical plume evolution trying to understand previously underestimated mixing ratios of chlorine oxides under cloud-free conditions and under situations where clouds form in the volcanic plume. Furthermore we will present results of the speciation of sulphur compounds in the volcanic plume, with a critical evaluation of the evolution with time of H2S and SO2.

von Glasow, R.

2007-12-01

330

Discovery, interception, and treatment of a groundwater plume: Oak Ridge National Laboratory  

SciTech Connect

A radiological groundwater plume was discovered to be discharging into a surface stream and portions of the storm drain network at Oak Ridge National Laboratory (ORNL). A CERCLA removal action was initiated to address the discharges. The plume was found to be migrating 65 degrees oblique to the overall hydraulic gradient and was identified only after historic data were analyzed and field tests were performed under the working hypothesis of stratabound flow and transport. A detailed geologic and hydrologic analysis was performed that accurately predicted the 3-dimensional plume configuration from a single point datum where significantly elevated contaminant levels were found in a bedrock core hole. Subsequent sampling found that direct discharges of contamination existed in the stream only in the location of the predicted stratum. The affected storm drain outfall discharges were suspected to be the major contributors to {sup 90}Sr surface water risk from ORNL. Thus, the selected removal action focused on eliminating the known seepage to the storm drain network. Intercept system operations reduced the total surface water {sup 90}Sr flux by about 90%. Ongoing investigations seek to identify the source of the plume with the hope that the intercept system may eventually be deactivated. However, the efficiency of the system exceeded expectations and demonstrated that a good understanding of the hydrodynamics is a prerequisite to success. The relatively trouble free operation of the system also indicates that simple technologies can serve as effective measures to address immediate problems.

Lee, R.; Ketelle, D. [Oak Ridge National Lab., TN (United States). Energy Div.

1996-06-01

331

Atmospheric chemistry of an Antarctic volcanic plume  

NASA Astrophysics Data System (ADS)

We report measurements of the atmospheric plume emitted by Erebus volcano, Antarctica, renowned for its persistent lava lake. The observations were made in December 2005 both at source, with an infrared spectrometer sited on the crater rim, and up to 56 km downwind, using a Twin Otter aircraft; with the two different measurement platforms, plume ages were sampled ranging from <1 min to as long as 9 h. Three species (CO, carbonyl sulfide (OCS), and SO2) were measured from both air and ground. While CO and OCS were conserved in the plume, consistent with their long atmospheric lifetimes, the downwind measurements indicate a SO2/CO ratio about 20% of that observed at the crater rim, suggesting rapid chemical conversion of SO2. The aircraft measurements also identify volcanogenic H2SO4, HNO3 and, recognized for the first time in a volcanic plume, HO2NO2. We did not find NOx in the downwind plume despite previous detection of NO2 above the crater. This suggests that near-source NOx was quickly oxidized to HNO3 and HO2NO2, and probably NO32-(aq), possibly in tandem with the conversion of SO2 to sulfate. These fast processes may have been facilitated by "cloud processing" in the dense plume immediately downwind from the crater. A further striking observation was O3 depletion of up to ˜35% in parts of the downwind plume. This is likely to be due to the presence of reactive halogens (BrO and ClO) formed through heterogeneous processes in the young plume. Our analysis adds to the growing evidence for the tropospheric reactivity of volcanic plumes and shows that Erebus volcano has a significant impact on Antarctic atmospheric chemistry, at least locally in the Southern Ross Sea area.

Oppenheimer, Clive; Kyle, Philip; Eisele, Fred; Crawford, Jim; Huey, Greg; Tanner, David; Kim, Saewung; Mauldin, Lee; Blake, Don; Beyersdorf, Andreas; Buhr, Martin; Davis, Doug

2010-01-01

332

No Ocean Source for the Enceladus Plumes  

NASA Astrophysics Data System (ADS)

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

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

2007-12-01

333

Ozone photochemistry in boreal biomass burning plumes  

NASA Astrophysics Data System (ADS)

We present an analysis of ozone photochemistry observed by aircraft measurements of boreal biomass burning plumes over Eastern Canada in the summer of 2011. Measurements of ozone and a number of key chemical species associated with ozone photochemistry, including non-methane hydrocarbons (NMHCs), nitrogen oxides (NOx) and total nitrogen containing species (NOy), were made from the UK FAAM BAe-146 research aircraft as part of the quantifying the impact of BOReal forest fires on tropospheric oxidants over the Atlantic using Aircraft and Satellites (BORTAS) experiment between 12 July and 3 August 2011. We found that ozone mixing ratios measured in biomass burning plumes were indistinguishable from non-plume measurements, but evaluating them in relationship to measurements of carbon monoxide (CO), total alkyl nitrates (?AN) and the surrogate species NOz (=NOy - NOx) revealed that the potential for ozone production increased with plume age. We used NMHC ratios to estimate photochemical ages of the observed biomass burning plumes between 0 and 15 days. Ozone production, calculated from ?O3/?CO enhancement ratios, increased from 0.020 ± 0.008 ppbv ppbv-1 in plumes with photochemical ages less than 2 days to 0.55 ± 0.29 ppbv ppbv-1 in plumes with photochemical ages greater than 5 days. In comparing ozone mixing ratios with components of the NOy budget we observed that plumes with ages between 2 and 4 days were characterised by high aerosol loading, relative humidity greater than 40%, and low ozone production efficiencies of 8 ppbv ppbv-1 relative to ?AN and 2 ppbv ppbv-1 relative to NOz. In plumes with ages greater than 4 days, ozone production efficiency increased to 473 ppbv ppbv-1 relative to ?AN and 155 ppbv ppbv-1 relative to NOz. From the BORTAS measurements we estimated that aged plumes with low aerosol loading were close to being in photostationary steady state and ozone production in younger plumes was inhibited by high aerosol loading and greater production of ?AN relative to ozone. The BORTAS measurements of ozone photochemistry in boreal biomass burning plumes were found to be consistent with previous summertime aircraft measurements made over the same region during the Arctic Research of the Composition of the troposphere (ARCTAS-B) in 2008 and Atmospheric Boundary Layer Experiment (ABLE 3B) in 1990.

Parrington, M.; Palmer, P. I.; Lewis, A. C.; Lee, J. D.; Rickard, A. R.; Di Carlo, P.; Taylor, J. W.; Hopkins, J. R.; Punjabi, S.; Oram, D. E.; Forster, G.; Aruffo, E.; Moller, S. J.; Bauguitte, S. J.-B.; Allan, J. D.; Coe, H.; Leigh, R. J.

2013-01-01

334

Deep carbon and helium in mantle plumes  

NASA Astrophysics Data System (ADS)

It is well known that helium abundances in mantle-derived basalts are approximately and globally correlated with CO2. Recent experimental work on carbonate melting in the deep upper mantle [1] potentially throws new light on this connection. This work shows that small amounts of carbonate melts should be formed in upwelling mantle even at low carbon concentrations of as little as 100 ppm. Such carbonate melts are expected to be extremely mobile and may ascend through the upper mantle at rates exceeding 1 m/yr, especially in view of the recently measured high permeability of mantle rocks [2]. Although published partitioning and solubility data for helium in silicates cover a rather large range of values, we assume that helium is nearly as incompatible as carbon in the presence of a carbonate liquid. Thus, ascending carbonatite liquids should become the major carrier phase for mantle helium. In several well-documented mantle hotspots ascribed to ascending mantle plumes, including Hawaii, Iceland and Galapagos, the high-3He/4He signal is asymmetrically distributed. In all three cases, the He signal is offset from the plume center in the "upstream" direction of asthenospheric flow driven by local plate motions. We propose that this asthenospheric flow tilts the plume. Primordial He, thought to be initially located in the plume center, is scavenged by a small amount of carbonatite liquid, which forms in the plume at depths of 400 km or more, migrates vertically through the tilted plume, and displaces the helium maximum from the plume core toward its margin. We model this process for the Hawaiian plume to explain the 3He/4He maximum located in Loihi melts, which sample the front edge of this plume, rather than in Mauna Loa or Kilauea melts, which sample the core of the plume. The model predicts significant displacements of the He signal derived from plume cores and decoupling of He from Sr, Nd, Pb isotope signatures in tilted plumes. [1] Dasgupta & Hirschmann (2006), Nature 440, 659-662. [2] Connolly et al. (2009) Nature. 462, 209-212.

Hofmann, Albrecht; Farnetani, Cinzia

2010-05-01

335

A Comparison of Wet and Dry Bent-Over Plumes  

Microsoft Academic Search

The theory of moist bent-over plume behavior given by Csanady and by Wigley and Slawson is expanded and clarified to illustrate the differences between moist and dry plume behavior under various atmospheric stability conditions associated with linear gradients of temperature and humidity. If plume types are defined according to the behavior of a dry plume in stable, neutral and unstable

T. M. L. Wigley; P. R. Slawson

1972-01-01

336

Cratonal lithosphere a potential recorder of ancient mantle plumes  

Microsoft Academic Search

In the conventional mantle plume hypothesis, hot plume material ponds at the base of the lithosphere. The deep cratonal lithosphere provides a record and a potential test of this aspect of plumes. First uplift and subsidence in the geological record give lthe more likely times of plume impingement. Second studies of pressure-temperature-time histories from zoned diamonds may make this process

N. H. Sleep

2004-01-01

337

Spreading in the near-field Merrimack River plume  

Microsoft Academic Search

A numerical simulation of the near-field Merrimack River plume is used to investi- gate how buoyant plumes spread within a few kilometers of an estuary mouth. There are three principal findings of this study. First, many properties of the plume are primarily a function radial distance from the estuary mouth, and are uniform across the arc of the plume. Second,

Robert D. Hetland; Daniel G. MacDonald

2007-01-01

338

Hyperspectral chemical plume quantification via background radiance estimation  

NASA Astrophysics Data System (ADS)

Existing chemical plume quantification algorithms assume that the off-plume radiance of a pixel containing the plume signal is unobservable. When the problem is limited to a single gas, the off-plume radiance may be estimated from the bands in which the gas absorption is nearly zero. It is then possible to compute the difference between the on- and off-plume radiances and solve for the plume strength from Beer's Law. The major advantage of this proposed method is that the gas strength can be resolved from the radiance difference so that the estimation error remains small for thick plumes.

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

2013-05-01

339

Modeling benzene plume elongation mechanisms exerted by ethanol using RT3D with a general substrate interaction module  

Microsoft Academic Search

A mathematical model was developed to evaluate the effect of the common fuel additive ethanol on benzene fate and transport in fuel-contaminated groundwater and to discern the most influential benzene plume elongation mechanisms. The model, developed as a module for the Reactive Transport in 3 Dimensions (RT3D) model, includes commonly considered fate and transport processes (advection, dispersion, adsorption, biodegradation, and

Diego E. Gomez; Phillip C. de Blanc; William G. Rixey; Phillip B. Bedient; Pedro J. J. Alvarez

2008-01-01

340

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

PubMed

Disposal of treated wastewater for more than 60 years onto infiltration beds on Cape Cod, Massachusetts produced a groundwater contaminant plume greater than 6 km long in a surficial sand and gravel aquifer. In December 1995 the wastewater disposal ceased. A long-term, continuous study was conducted to characterize the post-cessation attenuation of the plume from the source to 0.6 km downgradient. Concentrations and total pools of mobile constituents, such as boron and nitrate, steadily decreased within 1-4 years along the transect. Dissolved organic carbon loads also decreased, but to a lesser extent, particularly downgradient of the infiltration beds. After 4 years, concentrations and pools of carbon and nitrogen in groundwater were relatively constant with time and distance, but substantially elevated above background. The contaminant plume core remained anoxic for the entire 10-year study period; temporal patterns of integrated oxygen deficit decreased slowly at all sites. In 2004, substantial amounts of total dissolved carbon (7 mol C m(-2)) and fixed (dissolved plus sorbed) inorganic nitrogen (0.5 mol N m(-2)) were still present in a 28-m vertical interval at the disposal site. Sorbed constituents have contributed substantially to the dissolved carbon and nitrogen pools and are responsible for the long-term persistence of the contaminant plume. Natural aquifer restoration at the discharge location will take at least several decades, even though groundwater flow rates and the potential for contaminant flushing are relatively high. PMID:16572769

Repert, Deborah A; Barber, Larry B; Hess, Kathryn M; Keefe, Steffanie H; Kent, Douglas B; LeBlanc, Denis R; Smith, Richard L

2006-02-15

341

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

342

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

343

Trade-Off Between Delineation and Lighting on Freeway Interchanges.  

National Technical Information Service (NTIS)

The objective was to determine whether, with improved delineation, performance at partially lighted interchanges can approach performance under full lighting, particularly in rain. Two field studies were conducted. The first was to determine whether trans...

R. S. Hostetter K. W. Crowley G. W. Dauber E. L. Seguin

1989-01-01

344

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

345

Polymer delineation system. [Patent application: traffic lane lines  

DOEpatents

A delineation system (traffic lane lines) for highways is described in which polymerizable substances are applied to existing or newly prepared highway pavements. The substances would contain a suitable pigment and may incorporate reflective elements.

Woolman, S.; Steinberg, M.

1975-06-24

346

1. Photocopy of a measured drawing, delineator unknown, April 1919 ...  

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

1. Photocopy of a measured drawing, delineator unknown, April 1919 PLANS, SECTION, AND ELEVATIONS OF KRONPRINSENSGADE COMMERCIAL BUILDING (ADDRESS UNKNOWN) - Kronprinsensgade Area Study, Commercial Building, Crown Prince Street, Charlotte Amalie, St. Thomas, VI

347

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

348

Riparian ecotone: A functional definition and delineation for ...  

Treesearch

Forest Products Lab ... Description: We propose a geomorphic basis for defining riparian areas using the term: riparian ecotone, discuss how past definitions fall short, and illustrate how a linked sequence of definition, delineation, and riparian  ...

349

18 CFR 415.43 - Mapped and unmapped delineations.  

Code of Federal Regulations, 2013 CFR

...2012-04-01 true Mapped and unmapped delineations. 415.43 Section 415.43 Conservation of Power and Water Resources DELAWARE RIVER BASIN COMMISSION ADMINISTRATIVE MANUAL BASIN REGULATIONS-FLOOD PLAIN REGULATIONS Administration §...

2013-04-01

350

Simulation of plume dynamics using particle graphics  

NASA Astrophysics Data System (ADS)

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

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

2000-07-01

351

Smoke Plume Method of Measuring Upper Winds.  

National Technical Information Service (NTIS)

Contents: Development of a dependable 'Smoke producing' rocket to a height limit of 3000 to 4000 ft; Development of photographic techniques for sequentically recording the smoke plumes in three-dimensions, and, the techniques employed in the determination...

G. C. Gill A. W. Stohrer T. L. Sweeny

1968-01-01

352

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

353

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

354

Long-term fate of organic micropollutants in sewage-contaminated groundwater  

Microsoft Academic Search

Disposal of secondary sewage effluent by rapid infiltration has produced a plume of contaminated groundwater over 3500 m long near Falmouth, MA. Approximately 50 volatile organic compounds were detected and identified in the plume, at concentrations ranging from 10 ng\\/L to 500 μg\\/L, by closed-loop stripping and purge-and-trap in conjunction with gas chromatography-mass spectrometry. The dominant contaminants were di-, tri-

Larry B. Barber; E. Michael. Thurman; Michael P. Schroeder; Denis R. LeBlanc

1988-01-01

355

PRELIMINARY INVESTIGATION ON ANAEROBIC BIODEGRADATION OF BENZENE IN CONTAMINATED AQUIFER SEDIMENT  

Microsoft Academic Search

ABSTRACT The objectives of this research were to document,the anaerobic biodegradation of benzene in aquifer sediment recovered from a petroleum-contaminated aquifer near Rocky Point, N.C., and to identify the microbial conditions controlling its biodegradation. Laboratory-scale microcosms were constructed with contaminated sediment recovered from a section of the plume (mid-plume) from which previously excavated sediment had exhibited benzene biodegradation. Microcosms were

Melody J. Hunt; Morton A. Barlaz

2000-01-01

356

Physical scale modelling of adhered spill plume entrainment  

Microsoft Academic Search

This work provides new experimental data to characterise entrainment of air into adhered thermal spill plumes using physical scale modelling. For the two-dimensional plume, the rate of entrainment with respect to height of rise is approximately half that of an equivalent two-dimensional balcony spill plume. For the three-dimensional plume, the rate of entrainment appears to be linked to the plume

Roger Harrison; Michael Spearpoint

2010-01-01

357

NRL Satellite Volcanic Ash Plume Monitoring  

NASA Astrophysics Data System (ADS)

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) data sets that take advantage of their complimentary strengths since no one sensor has the required spectral, spatial and temporal attributes needed. This product suite would then be available to the Volcanic Ash Advisory Centers (VAAC) and other interested users via web distribution. Initially, GOES-West and the Japanese MTSAT data will be incorporated to view volcanic plumes within the north Pacific region. Although GEO sensor spectral channels are not optimized for ash detection, temporal changes over limited timeframes can assist in plume extraction, but not for those at the highest latitudes. Examples with multi-channel techniques will be highlighted via animations. LEO sensors provide a suite of spectral channels unmatched on GEO platforms and permit enhanced ash plume monitoring. NRL has exploited the Moderate Resolution Imaging Spectroradiometer (MODIS) and SeaWiFS via a “dust enhancement technique” that has demonstrated positive plume monitoring results. Multi-channel methods using the Advanced Very High Resolution Radiometer (AVHRR) will be highlighted to take advantage of the numerous NOAA LEO satellites carrying this wide swath sensor with frequent volcano overpasses at the higher latitudes. The DMSP Operational Linescan System (OLS) provides daytime visible/infrared, as well as night time visible data which has shown value in spotting ash plumes when sufficient lunar illumination is present. The following suite of products is potentially available for over twenty (20) volcano sites world-wide via our NexSat web site: http://www.nrlmry.navy.mil/NEXSAT.html (click on “region/sector” and select volcanoes on the bottom): 1) GEO vis/IR, GEO split window technique, 3) MODIS/SeaWiFS true color, 4) MODIS dust algorithm (plume detection), 5) fire or hotspot detection, 6) aerosol optical depth (AOD) for those oceanic bracketed locations, and 7) DMSP OLS night time visible imagery. Shortly, additional near real-time GEO/LEO data sets will be added and multiple ash plume detection techniques (published and under development) will be incorporated for comparison and evaluation. The satellite-derived volcanic ash plumes will be incorporated into the FAA’s Dynamic Ocean Track System (DOTS) Plus and Advanced Technologies and Oceanic Procedures (ATOP) for enhanced air traffic planning. ________________________________________

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

2009-12-01

358

A tidal plume front and internal solitons  

NASA Astrophysics Data System (ADS)

A tidal plume front (internal tidal bore) propagating from the Apalachicola Bay outflow into the northern Gulf of Mexico is examined in a brief set of observations. Temperature and salinity time series showed a radially spreading "pool" of estuarine water with a character similar to a previously observed "turbulent rotor", and with a following packet of internal solitons. Features associated with these observations may be pertinent to interpretation of remotely sensed plumes and to predictive modeling.

Johnson, Donald R.; Weidemann, Alan D.

1998-07-01

359

Dusk Side ULF Waves and Plasmaspheric Plumes  

NASA Astrophysics Data System (ADS)

Previous studies have shown frequent occurrence of compressional ULF waves with frequencies in the PC 5 range in the dusk side of the magnetosphere, from a distance of about 8 RE up to the magnetopause. These waves propagate sunward and towards the magnetopause with very low speeds in the plasma frame. Plasmaspheric plumes, extensions from the plasmasphere filled with relative cold plasma, are also a common presence in this region of the magnetosphere. Moreover, both phenomena appear preferentially after a weak increase in the geomagnetic activity. Here we discuss the relationship between the dusk side ULF waves and the plasmaspheric plumes. The ULF waves are identified and analyzed using magnetic field data from the FGM instrument onboard THEMIS. To identify the plasmaspheric plumes we use the spacecraft potential as a proxy for the particle density. Many events during April 2008 indicate a close relationship between ULF waves and plasmaspheric plumes. The waves are often detected between the plume and the magnetopause, but sometimes also within the plumes.

Dragos Constantinescu, Ovidiu; Glassmeier, Karl-Heinz; McFadden, James; Angelopoulos, V.; Dunlop, M. W.; Bogdanova, Y. V.; Berchem, J.; Eastwood, J.; Fazakerley, A.; Frey, H.; Hasagawa, H.; Lavraud, B.; Pu, Z.; Shen, C.; Sibeck, D.; Volwerk, M.; Wild, J.; Escoubet, C. P.; Taylor, M. G. G. T.

360

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

361

Thermal and Density Structure of Polar Plumes  

NASA Astrophysics Data System (ADS)

Normal incidence multilayer coated EUV/XUV optical systems provide a powerful technique for the study of the structure of the solar corona. Such systems permit the imaging of the full solar disk and corona with high angular resolution in narrow wavelength bands that are dominated by a single line or a line multiplet excited over a well defined range of temperatures. We have photometrically analysed, and derived temperature and density information from, images of polar plumes obtained with a multilayer Cassegrain telescope operating in the wavelength interval ? = 171 to 175 Å, which is dominated by Fe IX and Fe X emission. This observation was obtained in October 1987, and is the first high resolution observation of an astronomical object obtained with normal incidence multilayer optics techniques. We find that photometric data taken from this observation, applied to a simple, semi-empirical model of supersonic solar wind flow, are consistent with the idea that polar plumes are a source of the solar wind. However, we are not able to uniquely trace high speed streams to polar plumes. The temperatures that we observed are typically ˜ 1 500 000 K for both the plumes and the interplume regions, with the plume temperatures slightly higher than those of the surrounding atmosphere. Typical electron densities of the plume and interplume regions, respectively, are 5 × 109 cm-3 and 1 × 108 cm-3 at the limb of the Sun.

Walker, A. B. C., Jr.; Deforest, C. E.; Hoover, R. B.; Barbee, T. W., Jr.

1993-12-01

362

Nuclear thermal rocket plume interactions with spacecraft. Final report  

SciTech Connect

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

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

1997-05-01

363

Modeling of an MTBE plume at Pascoag, Rhode Island  

NASA Astrophysics Data System (ADS)

A numerical groundwater flow and mass transport model was developed to predict the extent of impact from methyl tertiary butyl ether (MTBE) release on a down-gradient drinking water well field. An MTBE incident in Pascoag, Rhode Island, was used as a case study and the plume’s past and future development was simulated using scenario analysis. The numerical code used was GeoSys/Rockflow, which permits a coupled flow and transport simulation as one object, thus alleviating the need for simulating the MTBE fate with separate flow and transport codes. The numerical model was built on available hydrogeological and chemical data as well as on GIS information of the site. By comparing the simulated results with observed field data, it was found that the model could provide reliable results even when the simulated aquifer was simplified to a two-dimensional flow and transport domain. Finally, the calibrated model was used for exploring a location that may be suitable for a new well field. Despite the model limitations associated with uncertainties of data and simplifying assumptions, numerical modeling of this MTBE contaminated site proved a useful tool and provided guidance for future municipal well field operation strategies and aquifer remediation alternatives.

Myrttinen, A.; Boving, T.; Kolditz, O.

2009-05-01

364

Factors controlling BTEX and chlorinated solvents plume length under natural attenuation conditions  

NASA Astrophysics Data System (ADS)

Natural attenuation is presently used at numerous sites where groundwater is contaminated. In order to simulate this attenuation, reactive transport models are often used but they are quite complex and depend on both physical and chemical conditions in the aquifer. As complex numerical models cannot be used to study all possible cases, we develop here analytical solutions to draw general conclusions. Our strategy, called MIKSS (Mixed Instantaneous and Kinetics Superposition Sequence), allows the calculation of the concentrations of all reacting substances in a plume. It is an extension of the superimposition principle that is able to treat the case of joint kinetics and instantaneous reactions. The basic equations have been extended to treat different reactions that occur in the plume core and at its fringe. At first we consider one organic substance degraded under all oxidising conditions (toluene for instance). For this problem the size of the plume depends on the reduced source width and on the ratio of the organic substance concentration to the sum of the electron acceptors' concentrations. For several BTEX substances having different degradation behaviour the formulation is similar, but leads to quite different plume lengths for each substance. Contrary to the case of one substance, the plumes can be quite long and may not satisfy the target risk level. For chlorinated solvents we developed a specific approach to take under consideration all reactions and particularly the competition for hydrogen. A formula is given to assess the size of the plume core, i.e. the zone with highly reducing conditions. The factors influencing the core length are the same as for BTEX (source width, dispersivity, organic carbon content). The size of the TCE plume is calculated from the plume core length and the kinetic constant of TCE degradation. Using assumptions of degradation constants for DCE and VC it is also possible to calculate the longitudinal concentration profile of these substances. The degradation of moderately substituted solvents under oxic conditions reduces the size of their plumes but under these conditions TCE becomes the major threat. Among the conditions studied in this paper, very few chlorinated solvents sites can lead to a negligible risk at an acceptable distance from the source.

Atteia, O.; Guillot, C.

2007-02-01

365

OZONE PRODUCTION IN URBAN PLUMES.  

SciTech Connect

Ozone levels observed during a field campaign in Houston were significantly higher than that observed in Phoenix or Philadelphia. An examination of the slope of O{sub x} versus NO{sub z} in the urban plumes shows that NO{sub x} is used 2 to 3 times more efficiently in Houston as compared with Phoenix and Philadelphia. Representative values of OPEx are 7-12, 3, and 4, in Houston, Phoenix, and Philadelphia. Aircraft observations have been used to calculate P(O{sub 3})/P(NO{sub z}). Values in Houston are significantly higher than in Phoenix and Philadelphia. We show that P(O{sub 3})/P(NO{sub z}) is proportional to a VOC/NO{sub 2}-OH reactivity ratio. High values of P(O{sub 3})/P(NO{sub z}) in Houston are due to emissions of reactive olefins from the ship channel region. It is significant that high values of P(O{sub 3})/P(NO{sub z}) occur at NO{sub x} levels up to several 10's of ppb. Not only is the chemistry efficient but it will be long lasting. The occurrence of high NO{sub x} and high OPEx is fostered by the co-location of VOC and NO{sub x} sources in the Houston industrial areas.

KLEINMAN,L.

2001-09-17

366

Recovering the release history of a groundwater contaminant using a non-linear least-squares method  

Microsoft Academic Search

A non-linear least-squares (NLS) method is used without regularization to recover the release history of a groundwater contaminant plume from its current measured spatial distribution. The flow system is assumed to be one-dimensional, with the plume originating from a known single site. The solution is found to be very sensitive to noise and to the extent to which the plume

S. Alapati; Z. J. Kabala

2000-01-01

367

Morphology, dynamics and plasma parameters of plumes and inter-plume regions in solar coronal holes  

NASA Astrophysics Data System (ADS)

Coronal plumes, which extend from solar coronal holes (CH) into the high corona and—possibly—into the solar wind (SW), can now continuously be studied with modern telescopes and spectrometers on spacecraft, in addition to investigations from the ground, in particular, during total eclipses. Despite the large amount of data available on these prominent features and related phenomena, many questions remained unanswered as to their generation and relative contributions to the high-speed streams emanating from CHs. An understanding of the processes of plume formation and evolution requires a better knowledge of the physical conditions at the base of CHs, in plumes and in the surrounding inter-plume regions. More specifically, information is needed on the magnetic field configuration, the electron densities and temperatures, effective ion temperatures, non-thermal motions, plume cross sections relative to the size of a CH, the plasma bulk speeds, as well as any plume signatures in the SW. In spring 2007, the authors proposed a study on `Structure and dynamics of coronal plumes and inter-plume regions in solar coronal holes' to the International Space Science Institute (ISSI) in Bern to clarify some of these aspects by considering relevant observations and the extensive literature. This review summarizes the results and conclusions of the study. Stereoscopic observations allowed us to include three-dimensional reconstructions of plumes. Multi-instrument investigations carried out during several campaigns led to progress in some areas, such as plasma densities, temperatures, plume structure and the relation to other solar phenomena, but not all questions could be answered concerning the details of plume generation process(es) and interaction with the SW.

Wilhelm, K.; Abbo, L.; Auchère, F.; Barbey, N.; Feng, L.; Gabriel, A. H.; Giordano, S.; Imada, S.; Llebaria, A.; Matthaeus, W. H.; Poletto, G.; Raouafi, N.-E.; Suess, S. T.; Teriaca, L.; Wang, Y.-M.

2011-06-01

368

Plume and lithologic profiling with surface resistivity and seismic tomography  

SciTech Connect

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

Watson, David B [ORNL; Doll, William E. [Battelle; Gamey, Jeff [Battelle; Sheehan, Jacob R [ORNL; Jardine, Philip M [ORNL

2005-03-01

369

Geochemistry of the oldest Atlantic oceanic crust suggests mantle plume involvement in the early history of the central Atlantic Ocean  

NASA Astrophysics Data System (ADS)

Controversy has surrounded the issue of whether mantle plume activity was responsible for Pangaean continental rifting and massive flood volcanism (resulting in the Central Atlantic Magmatic Province or CAMP, emplaced around 200 Ma) preceding the opening of the central Atlantic Ocean in the Early Mesozoic. Our new Sr-Nd-Pb isotopic and trace element data for the oldest basalts sampled from central Atlantic oceanic crust by deep-sea drilling show that oceanic crust generated from about 160 to 120 Ma displays clear isotopic and chemical signals of plume contamination (e.g., 87Sr/86Sri=0.7032-0.7036, ?Nd(t)=+6.2 to +8.2, incompatible element patterns with positive Nb anomalies), but these signals are muted or absent in crust generated between 120 and 80 Ma, which resembles young Atlantic normal mid-ocean ridge basalt. The plume-affected pre-120 Ma Atlantic crustal basalts are isotopically similar to lavas from the Ontong Java Plateau, and may represent one isotopic end-member for CAMP basalts. The strongest plume signature is displayed near the center of CAMP magmatism but the hotspots presently located nearest this location in the mantle reference frame do not appear to be older than latest Cretaceous and are isotopically distinct from the oldest Atlantic crust. The evidence for widespread plume contamination of the nascent Atlantic upper mantle, combined with a lack of evidence for a long-lived volcanic chain associated with this plume, leads us to propose that the enriched signature of early Atlantic crust and possibly the eruption of the CAMP were caused by a relatively short-lived, but large volume plume feature that was not rooted at a mantle boundary layer. Such a phenomenon has been predicted by recent numerical models of mantle circulation.

Janney, Philip E.; Castillo, Paterno R.

2001-10-01

370

Laboratory Experiments Simulating the Effects of Variable Discharge on Buoyant Coastal Plumes  

NASA Astrophysics Data System (ADS)

River plumes are of great importance to coastal ecosystems because they carry nutrients and contaminants from upstream, which can become trapped near the coast in a growing anticyclonic eddy, or bulge. The degree to which river water is trapped in this coastal eddy is associated strongly with the river discharge. In meso- to macro-tidal systems, ebb and flood tidal phases may result in increases and decreases, respectively, of the effective river discharge of a similar magnitude to the discharge itself. Thus, accumulation of fluid in the bulge may depend on the relative magnitude of the tidal forcing or other modulations of the river discharge. Field observations suggest that under some conditions, discharge variation can cause the anticyclonic eddy to become detached and swept downstream, rather than continuing to grow near the mouth. We carry out laboratory experiments to simulate the effects of periodically varying discharge on buoyant coastal plumes over a range of oscillation periods by injecting a sinusoidally pulsed freshwater inflow into a 2 meter diameter rotating tank of salt water. The depth of the plume in the vicinity of the river mouth is determined from an overhead camera using an optical thickness technique. Using this technique, the temporal evolution of the plume volume can be determined directly. Preliminary results confirm that approximately 65% of the discharge remains in the bulge region in the absence of tidal forcing. In the presence of tidal forcing plume growth appears to be slowed, thereby increasing the transport of buoyant water downstream in the coastal current. Finally, the plume is almost entirely arrested when the pulsing frequency is half of the rotation frequency.

Avener, M. E.; Horner-Devine, A. R.; Rhines, P. B.

2008-12-01

371

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

Microsoft Academic Search

A wind tunnel investigation was conducted to study the flow field in which separation is caused by an expanding plume, with emphasis on effects associated with periodic unsteadiness in the plume. The separation shock was photographed with high speed motion pictures, from which mean shock position and excursion data were reported. Pressure fluctuations were measured beneath the separation shock. A

J. O. Doughty

1976-01-01

372

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

373

A buoyant plume adjacent to a headland—Observations of the Elwha River plume  

Microsoft Academic Search

Small rivers commonly discharge into coastal settings with topographic complexities – such as headlands and islands – but these settings are underrepresented in river plume studies compared to more simplified, straight coasts. The Elwha River provides a unique opportunity to study the effects of coastal topography on a buoyant plume, because it discharges into the Strait of Juan de Fuca

Jonathan A. Warrick; Andrew W. Stevens

2011-01-01

374

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

375

CORONAL PLUMES IN THE FAST SOLAR WIND  

SciTech Connect

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 {approx}50 km s{sup -1}, 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 distances 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 [Jet Propulsion Laboratory, Pasadena, CA 91109 (United States); Lionello, Roberto; Linker, Jon A.; Mikic, Zoran, E-mail: mvelli@mail.jpl.nasa.gov, E-mail: lionel@predsci.com, E-mail: linkerj@predsci.com, E-mail: mikicz@predsci.com [Predictive Science, Inc., San Diego, CA 92121-2910 (United States)

2011-07-20

376

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

377

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

378

Wind-Forced Baroclinic Beta-Plumes  

NASA Astrophysics Data System (ADS)

A planetary beta-plume is a classical example of oceanic circulation induced by a localized vorticity source or sink that allows an analytical description in simplistic cases. Its barotropic structure is a zonally-elongated, gyre-like cell governed by the Sverdrup circulation on the beta-plane. The dominant zonal currents, found west of the source/sink, are often referred to as zonal jets. This simple picture describes the depth-integrated flow. Previous studies have investigated beta-plumes in a reduced-gravity framework or using other simple models with a small number of vertical layers, thereby lacking representation of the vertical structure. In addition, most previous studies use a purely linear regime without considering the role of eddies. However, these jets are often associated with strong lateral shear that makes them unstable under increased forcing. The circulation in such a nonlinear regime may involve eddy-mean flow interactions, which modify the time-averaged circulation. Here, the baroclinic structures of linear and nonlinear wind-forced beta-plumes are studied using a continuously-stratified, primitive equation, eddy-permitting ocean model (ROMS). The model is configured in an idealized rectangular domain for the subtropical ocean with a flat bottom. The surface wind forcing is a steady anticyclonic Gaussian wind vortex, which provides a localized vorticity source in the center of the domain. The associated wind stress curl and Ekman pumping comprise downwelling in the vortex center surrounded by a ring of weaker upwelling. Under weak forcing, the simulated steady-state circulation corresponds well with a theoretical linear beta-plume. While its depth-integrated transport exhibits a set of zonal jets, consistent with Sverdrup theory, the baroclinic structure of the plume is remarkably complex. Relatively fast westward decay of the surface currents occurs simultaneously with the deepening of the lower boundary of the plume. This deepening suggests that vertically-propagating Rossby waves may be involved. As the magnitude of the forcing increases, the solution becomes nonlinear, with cyclonic and anticyclonic mesoscale eddies aligned along different lobes of the plume. Such regime change alters not only the appearance of snapshots but also the number, locations, and amplitudes of lobes in the long-time average. A westward vertical broadening of the plume is also found in this nonlinear case. Implications for understanding the baroclinic structure of the Hawaiian Lee Counter-Current - a real world example of wind-induced beta-plume - are discussed.

Belmadani, A.; Maximenko, N. A.; Melnichenko, O.; Schneider, N.; Di Lorenzo, E.

2011-12-01

379

Dissolved Organic Metals in the Hydrothermal Plume  

NASA Astrophysics Data System (ADS)

In the hydrothermal plume, there are the unique microbiological communities and the microorganism utilizes various chemical substances. The interactions between heavy metals and microorganisms in the hydrothermal plume are important to comprehend the oceanic geochemical cycles of heavy metals. It is considered that the heavy metals in hydrothermal plume are organically bound with dissolved organic matter derived from the hydrothermal microorganism. This study funded by the O`Archaean ParkO_L project of MEXT is a first attempt to observe the bioavailability of heavy metals in hydrothermal plume. The hydrothermal plume samples were taken from two different kinds of hydrothermal sites, the Suiyo Seamount caldera and the Central Indian Ridge. The mini CTDT-RMS mounted twelve 1.2L Niskin bottles was installed on the manned submersible, and the hydrothermal plume samples were collected by taking the distance from the hydrothermal vents gradually. The solid phase extraction technique in C18 Sep-Pak cartridge (Millipore Waters) was used to extract the dissolved organic matter from the hydrothermal plume samples. Dissolved heavy metals (Al, Mn, Fe, Cu, Zn, Co, Ni, As, Mo, Cd and Pb) bound with C18 Sep-Pak extractable organic matter, dissolved organic metals, were analyzed by GFAAS. In all measured heavy metals, the dissolved organic metals existed in the hydrothermal plume samples collected from two sites. The concentration of the dissolved organic metals ranged from 0.5nM to 30nM and was about 1/1000~1/100 of the total dissolved heavy metals concentration. It suggests that these heavy metals were bound with organic matter originated in the hydrothermal microorganism. Though the abundance of the organism in the Central Indian Ridge is larger than that in the Suiyo Seamount caldera, the concentration of the dissolved organic metals in the plume samples at the Suiyo Seamount caldera was higher than that at the Central Indian Ridge. These results indicate that the bioavailability of heavy metals is different in two sites.

Shitashima, K.

2003-12-01

380

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

381

[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

2013-08-20

382

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

383

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

384

Aeroacoustics of advanced STOVL aircraft plumes  

NASA Astrophysics Data System (ADS)

This paper summarizes a basic and well-controlled experimental study involving flow visualization and noise measurements to define the acoustic and flow fields of single plumes impinging on a simulated ground plane. The flow visualization was made by strobing a laser light source at the discrete frequencies generated by the impingement of the jets and measured by a nearfield microphone. This enabled visualization of instability waves generated by the interaction between the plumes and the sound generated during impingement, and also by dynamic coupling between the two plumes. These data were acquired as a function of distance between the ground and the nozzle exit. Nearfield acoustic data were acquired simultaneously. Data for nozzle diameters of 0.265 in. and 0.4 in. are described. For selected nozzles, effects of exit boundary layer characteristics and nozzle protrusion through a simulated aircraft body are also presented.

Ahuja, K. K.; Spencer, D. A.

385

Spectroscopic diagnostics of plume rebound and shockwave dynamics of confined aluminum laser plasma plumes  

SciTech Connect

Generation and expansion dynamics of aluminum laser plasma plumes generated between parallel plates of varying separation ({Delta}Z = 2.0, 3.2, 4.0, and 5.6 mm), which confined plume expansion normal to the ablation surface, were diagnosed. Space and time resolved visible emission spectroscopy in the spectral range {lambda} = 355-470 nm and time gated visible imaging were employed to record emission spectra and plume dynamics. Space and time resolved profiles of N{sub e} (the electron density), T{sub e} (the electron temperature), and T{sub ionz} (the ionization temperature) were compared for different positions in the plasma plume. Significant modifications of the profiles of the above parameters were observed for plasma-surface collisions at the inner surface of the front plate, which formed a barrier to the free expansion of the plasma plume generated by the laser light on the surface of the back plate. Shockwave generation at the collision interface resulted in delayed compression of the low-density plasma plume near the inner ablation surface, at late stages in the plasma history. Upon exiting the cavity formed by the two plates, through an aperture in the front plate, the plasma plume underwent a second phase of free expansion.

Yeates, P. [National Centre for Plasma Science and Technology (NCPST), Dublin City University (DCU), Glasnevin, Dublin 7 (Ireland); Kennedy, E. T. [National Centre for Plasma Science and Technology (NCPST), Dublin City University (DCU), Glasnevin, Dublin 7 (Ireland); School of Physical Sciences, Dublin City University (DCU), Glasnevin, Dublin 7 (Ireland)

2011-06-15

386

Spectroscopic diagnostics of plume rebound and shockwave dynamics of confined aluminum laser plasma plumes  

NASA Astrophysics Data System (ADS)

Generation and expansion dynamics of aluminum laser plasma plumes generated between parallel plates of varying separation (?Z = 2.0, 3.2, 4.0, and 5.6 mm), which confined plume expansion normal to the ablation surface, were diagnosed. Space and time resolved visible emission spectroscopy in the spectral range ? = 355-470 nm and time gated visible imaging were employed to record emission spectra and plume dynamics. Space and time resolved profiles of Ne (the electron density), Te (the electron temperature), and Tionz (the ionization temperature) were compared for different positions in the plasma plume. Significant modifications of the profiles of the above parameters were observed for plasma-surface collisions at the inner surface of the front plate, which formed a barrier to the free expansion of the plasma plume generated by the laser light on the surface of the back plate. Shockwave generation at the collision interface resulted in delayed compression of the low-density plasma plume near the inner ablation surface, at late stages in the plasma history. Upon exiting the cavity formed by the two plates, through an aperture in the front plate, the plasma plume underwent a second phase of free expansion.

Yeates, P.; Kennedy, E. T.

2011-06-01

387

Enceladus Plumes: A Boiling Liquid Model  

NASA Astrophysics Data System (ADS)

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

Nakajima, Miki; Ingersoll, A. P.

2012-10-01

388

Application of inverse methods to contaminant source identification from aquitard diffusion profiles at Dover AFB, Delaware  

Microsoft Academic Search

This paper presents a refinement and expansion of our previously described efforts to estimate contaminant plume history from observed contaminant concentrations within a low-permeability aquitard at the site of a field-scale groundwater remediation experiment at Dover Air Force Base. At this site, a two-layer aquitard has been contaminated with tetrachloroethene and trichloroethene through diffusive mass transfer from an overlying contaminated

Chongxuan Liu; William P. Ball

1999-01-01

389

BrO formation in the plume of Pacaya volcano, plume chemistry at high resolution plume ages  

Microsoft Academic Search

During February 2010 we carried out gas emission studies of the plume of Pacaya volcano (Guatemala). The subduction zone volcano Pacaya which is characterized by basaltic to basaltic andesitic lava is located 40 km south of Guatemala City. Recent unrest from this volcano consisted of several events in the last decades in form of lava flows and strombolian explosions as

N. Bobrowski; L. Vogel; V. R. Cáceres Espinosa; C. Kern; U. Platt

2010-01-01

390

Tracking Iceland Plume Motion Using Trace Element Geochemistry  

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

391

Using Groundwater Age and Other Isotopic Signatures to Delineate Groundwater Flow and Stratification  

SciTech Connect

Isotopic tracers, such as stable isotopes of the water molecule and tritium, have been used in investigations of groundwater flow and transport and recharge water source for several decades. While these data can place hard constraints on groundwater flow rates, the degree of vertical flow between aquifers and across aquitards, and recharge source area(s), they are rarely used, even for validation, in conceptual or numerical models of groundwater flow. The Groundwater Ambient Monitoring and Assessment Program, sponsored by the California State Water Resources Control Board, and carried out in collaboration with the U.S. Geological Survey, has provided the means to gather an unprecedented number of tritium-helium groundwater ages in the basins of California. As the examples below illustrate, a collection of groundwater ages in a basin allows delineation of recharge areas (youngest ages), bulk flow rates and flowpaths, as well as a means of assessing susceptibility to anthropogenic contaminants.

Moran, J E; Hudson, G B

2005-08-31

392

Vapor intrusion from entrapped NAPL sources and groundwater plumes  

NASA Astrophysics Data System (ADS)

Volatile organic compounds (VOC) are commonly found entrapped as non-aqueous phase liquids (NAPLs) in the soil pores or dissolved in groundwater at industrial waste sites and refineries. Vapors emitted from these contaminant sources readily disperse into the atmosphere, into air-filled void spaces within the soil, and migrate below surface structures, leading to the intrusion of contaminant vapors into indoor air through basements and other underground structures. This process referred to as vapor intrusion (VI) represents a potential threat to human health, and is a possible exposure pathway of concern to regulatory agencies. To assess whether this exposure pathway is present, remediation project managers often rely in part on highly simplified screening level models that do not take into consideration the complex flow dynamics controlled by subsurface heterogeneities and soil moisture conditions affected by the mass and heat flux boundary conditions at the land/atmospheric interface. A research study is under way to obtain an improved understanding of the processes and mechanisms controlling vapor generation from entrapped NAPL sources and groundwater plumes, their subsequent migration through the subsurface, and their attenuation in naturally heterogeneous vadose zones under various natural physical, climatic, and geochemical conditions. Experiments conducted at multiple scales will be integrated with analytical and numerical modeling and field data to test and validate existing VI theories and models. A set of preliminary experiments where the fundamental process of vapor generation from entrapped NAPL sources and dissolved plumes under fluctuating water were investigated in small cells and two-dimensional test tanks. In another task, intermediate scale experiments were conducted to generate quantitative data on how the heat and mass flux boundary conditions control the development of dynamic VI pathways. The data from the small cell and tank experiments were used to test whether the equilibrium mass transfer assumption is valid under normal pressure gradients generated from atmospheric pressure variations and fluctuations of pressure in the building. The data from the intermediate scale airflow experiments were used to validate a numerical models based on a multi-physics simulator. These analyses will help us to evaluate the significance of the boundary conditions at the land/ atmospheric interface on the development of dynamic air pathways that transmit vapors from contaminant sources to buildings. The experimental findings and models are used to design a set of experiments in a coupled wind tunnel/ porous media test facility where integrated models of atmospheric and shallow subsurface interaction and up-scaling theories will be tested and validated.

Illangasekare, Tissa H.; Sakaki, Toshihiro; Christ, John; Petri, Bejamin; Sauck, Carolyn; Cihan, Abdullah

2010-05-01

393

Using fuzzy clustering methods for delineating urban housing submarkets  

Microsoft Academic Search

This study investigates whether a fuzzy clustering method is of any practical value in delineating urban housing submarkets relative to clustering methods based on classic (or crisp) set theory. A fuzzy c-means algorithm is applied to obtain fuzzy set membership degree of census tracts to housing submarkets defined within a metropolitan area. Issues of choosing algorithm parameters are discussed on

Sungsoon Hwang; Jean-claude Thill

2007-01-01

394

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

395