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1

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

USGS Publications Warehouse

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

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

2011-01-01

2

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

2011-07-01

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 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 ? 13C CH4 from an average of - 57.6‰ (± 1.7‰) in the methanogenic zone to - 39.6‰ (± 8.7‰) at 105 m downgradient, strongly suggest CH 4 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 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.

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

2011-07-01

4

Migration of contaminants in groundwater at a landfill: A case study. 1. Groundwater flow and plume delineation  

NASA Astrophysics Data System (ADS)

A landfill-derived contaminant plume with a maximum width of ˜600 m, a length of ˜700 m and a maximum depth of 20 m in an unconfined sand aquifer was delineated by means of a monitoring network that includes standpipe piezometers, multilevel point-samplers and bundle-piezometers. The extent of detectable contamination caused by the landfill, which began operation in 1940 and which became inactive in 1976, was determined from the distributions of chloride, sulfate and electrical conductance in the sand aquifer, all of which have levels in the leachate that are greatly above those in uncontaminated groundwater. The maximum temperature of groundwater in the zone of contamination beneath the landfill is 12°C, which is 4-5°C above background. The thermal plume in the aquifer extends ˜150 m downgradient from the centre of the landfill. A slight transient water-table mound exists beneath the landfill in the late spring and summer in response to snowmelt and heavy rainfall. Beneath the landfill, the zone of leachate contamination extends to the bottom of the aquifer, apparently because of transient downward components of hydraulic gradient caused by the water-table mound and possibly because of the higher density and lower viscosity of the contaminated water. Values of hydraulic conductivity, which show variations due to local heterogeneity, were obtained from slug tests of piezometers, from pumping tests and from laboratory tests. Because of the inherent uncertainty in the aquifer parameter values, the 38-yr. frontal position of the plume calculated using the Darcy equation with the assumption of plug flow can differ from the observed frontal position by many hundreds of metres, although the use of mean parameter values produces a close agreement. The width of the plume is large relative to the width of the landfill and can be accounted for primarily by variable periods of lateral east- and westward flow caused by changes in water-table configuration due to the variable nature of recharge. Northward from the landfill, the vertical thickness of the plume decreases and the top of the plume is farther below the water table. The thickness of the zone of uncontaminated groundwater above the plume increases northward as the area of recharge of uncontaminated water downflow from the landfill increases. Because dispersion in the vertical direction is weak, there is very little mixing between the overlying zone of recharge water and the contaminant plume. Concentration profiles are irregular beneath and near the landfill and become smooth downgradient where the maximum concentrations are much less than those beneath landfill. These features are attributed to a strong influence of longitudinal dispersion. The plume passes beneath a small shallow stream near the landfill without significant influence on the stream.

MacFarlane, D. S.; Cherry, J. A.; Gillham, R. W.; Sudicky, E. A.

1983-05-01

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

Steven Lev

6

Delineation of discharge areas of two contaminant plumes by use of diffusion samplers, Johns Pond, Cape Cod, Massachusetts, 1998  

USGS Publications Warehouse

Diffusion samplers were installed in the bottom of Johns Pond, Cape Cod, Massachusetts, to confirm that volatile organic compounds from the Storm Drain-5 (SD-5) plume emanating from the Massachusetts Military Reservation (MMR) were discharging into the pond. An array of 134 vapor-diffusion samplers was buried by divers about 0.5 feet below the pond bottom in the presumed discharge area of the SD-5 plume and left in place for about 2 weeks to equilibrate. Two areas of high concentrations of volatile organic compounds (VOCs) were identified. Samples from the first area contained trichloroethene (TCE) and tetrachloroethene with concentrations in vapor as high as 890 and 667 parts per billion by volume, respectively. This discharge area is about 1,000 feet wide, extends from 100 to 350 feet offshore, and is interpreted to be the discharge area of the SD-5 plume. Samples from the second area were located closer to shore than the discharge area of the SD-5 plume and contained unexpectedly high vapor concentrations of TCE (more than 40,000 parts per billion by volume). Ground-water samples collected with a drive-point sampler near the second area had aqueous TCE concentrations as high as 1,100 micrograms per liter. Subsequently, a more closely spaced array of 110 vapor-diffusion samplers was installed to map the area of elevated TCE concentrations . The discharge area detected with the samplers is about 75 feet wide and extends from about 25 to 200 feet offshore . TCE vapor concentrations in this area were as high as 42,800 parts per billion by volume. TCE concentrations in micrograms per liter in water-diffusion samples from 15 selected sites in the two discharge areas were about 35 times lower than the TCE concentrations in parts per billion by volume in corresponding vapor-diffusion samples. The difference in values is due to the volatile nature of TCE and the different units of measure. TCE was detected in diffusion samplers set in the pond water column above the plume discharge areas, but the TCE concentrations were 20 to 30 times lower than the corresponding levels in diffusion samplers buried in the pond bottom.

Savoie, Jennifer G.; LeBlanc, D.R.; Blackwood, D.S.; McCobb, T.D.; Rendigs, R. R.; Clifford, Scott

2000-01-01

7

Gaussian modeling of contaminant plumes  

SciTech Connect

The Gaussian plume model is based on the concept that a groundwater contaminant plume in a homogeneous medium can be modeled by a combination of discrete releases from a point source. Each of the instantaneous releases is represented by a three-dimensional Gaussian distribution modified to reflect processes encountered in groundwater contaminant transport, such as dispersion, retardation and decay. The Gaussian plume model provides the same problem-solving capability provided by analytical solutions but with less mathematical complexity and computational requirements. In addition, the Gaussian plume model offers solutions not readily available through analytical solutions because the basic discrete components are independent of the temporal and spatial characteristics of the source to be modeled.

Blackwelder, L.S.; Smoot, J.L. [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Civil and Environmental Engineering

1995-11-01

8

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

Microsoft Academic Search

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

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

2004-01-01

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

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

11

ModBack - simplified contaminant source zone delineation using backtracking  

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

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

RAPID REMOVAL OF A GROUNDWATER CONTAMINANT PLUME.  

USGS Publications Warehouse

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

Lefkoff, L. Jeff; Gorelick, Steven M.

1985-01-01

15

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

SciTech Connect

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

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

1994-12-31

16

Monopropellant thruster exhaust plume contamination measurements  

NASA Technical Reports Server (NTRS)

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

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

1977-01-01

17

Reaction front formation in contaminant plumes  

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

18

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

USGS Publications Warehouse

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

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

1992-01-01

19

Reaction front formation in contaminant plumes.  

PubMed

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

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

2014-12-15

20

Modeling Multidimensional Contaminant Plume Growth With Fractal Scaling  

Microsoft Academic Search

Granular and fractured aquifers have long been observed to exhibit fractal scaling. The growth of contaminant plumes in these aquifers will also exhibit fractal scaling with unique scaling rates in different (e.g. longitudinal and transverse) directions. A differential equation that can model this type of plume growth is a generalization of equations that govern the alpha -stable motions first described

R. Schumer; D. A. Benson; M. M. Meerschaert

2001-01-01

21

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

22

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

SciTech Connect

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

Smuin, D.R.

1993-01-01

23

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

24

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

25

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

NASA Astrophysics Data System (ADS)

In the framework of the EU FP7 project ModelPROBE, broadband spectral induced polarization (SIP) measurements were conducted at a former hydrogenation plant in Zeitz for the characterization of a hydrocarbon contaminant plume. In the source area total concentrations of BTEX contaminants partly exceed 1.5 g/l. Previous studies at the laboratory scale have demonstrated the sensitivity of SIP measurements to different concentrations of organic minerals; however, only few studies have been conducted at the field scale. The aim of this study was to investigate the potential of SIP imaging to delineate areas with different BTEX concentrations. SIP measurements were performed in the frequency range from 60 mHz to 1 kHz along a 120 m profile across the area of the former hydrogenation plant. At a later stage, a trench was excavated along the location of the profile in order to remove pipes, foundations and different sources of anthropogenic noise associated with the hydrogenation plant. Thereafter, SIP measurements were repeated inside the trench to study the effect of anthropogenic noise on the SIP images. Computed images for the data collected before and after the excavation of the trench show similar results validating the proposed approach even in the presence of anthropogenic noise. SIP images, for frequencies below 100 Hz, exhibit two main anomalies: low phase shift values (~ 5 mrad) for locations with free phase product (BTEX concentrations > 1.7 g/l); whereas relatively high polarization values (> 10 mrad) were observed for lower BTEX concentrations (1 - 1.7 g/l). Moreover, the spectral response of the areas where free phase product was detected reveals a flattened spectrum; while the areas with lower concentrations exhibit a typical Cole-Cole response. Based on these results, SIP imaging appears to be a suitable tool to delineate source-zones at highly contaminated sites.

Flores Orozco, A.; Kemna, A.; Oberdoerster, C.; Zschornack, L.; Leven, C.; Dietrich, P.; Weiss, H.

2011-12-01

26

Hydrogeophysical investigations of the former S-3 ponds contaminant plumes  

SciTech Connect

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

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

2013-01-01

27

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

28

Contaminant plumes containment and remediation focus area. Technology summary  

SciTech Connect

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

NONE

1995-06-01

29

OBSERVATIONS FROM CONTAMINANT PLUMES ON LONG ISLAND  

EPA Science Inventory

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

30

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

PubMed

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

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

2006-01-10

31

Contamination control and plume assessment of low-energy thrusters  

NASA Technical Reports Server (NTRS)

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

Scialdone, John J.

1993-01-01

32

Shuttle primary reaction control system engine exhaust plume contamination effects  

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

33

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...

34

Hall Effect Thruster Plume Contamination and Erosion Study  

NASA Technical Reports Server (NTRS)

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

Jaworske, Donald A.

2000-01-01

35

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

USGS Publications Warehouse

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

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

1996-01-01

36

In cooperation with Fort Peck Tribes Office of Environmental Protection Delineation of Brine Contamination in and near the  

E-print Network

Contamination in and near the East Poplar Oil Field, Fort Peck Indian Reservation, Northeastern Montana, 2004;#12;Delineation of Brine Contamination in and near the East Poplar Oil Field, Fort Peck Indian Reservation citation: Thamke, J.N., and Smith, B.D., 2014, Delineation of brine contamination in and near the East

Torgersen, Christian

37

Using sequential indicator simulation to assess the uncertainty of delineating heavy-metal contaminated soils  

Microsoft Academic Search

Mapping the spatial distribution of soil pollutants is essential for delineating contaminated areas. Currently, geostatistical interpolation, kriging, is increasingly used to estimate pollutant concentrations in soils. The kriging-based approach, indicator kriging (IK), may be used to model the uncertainty of mapping. However, a smoothing effect is usually produced when using kriging in pollutant mapping. The detailed spatial patterns of pollutants

Kai-Wei Juang; Yue-Shin Chen; Dar-Yuan Lee

2004-01-01

38

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 ...

39

Numerical stochastic analysis of groundwater contaminant transport and plume containment  

NASA Astrophysics Data System (ADS)

First- and second-order reliability methods (FORM and SORM) are applied as alternatives to the Monte Carlo simulation method in the probabilistic analysis of groundwater contaminant transport and remediation. A two-dimensional finite-element model is interfaced with a reliability analysis program to account for uncertainty in aquifer media. Hydraulic conductivity is modeled as a spatial random field with prescribed marginal probability distribution and correlation structure. FORM and SORM provide the probability that a contaminant exceeds a target level at a well, termed the probability of failure. Sensitivity of the probability of failure to basic uncertainty in grid block conductivities is also obtained, at no additional computational effort. Component reliability is used to analyze failure in a single well. Results indicate that, at the most likely failure scenario, grid block conductivities attain their maximum value near the source, the receptor well, and along the stream tubes connecting the two. System reliability is used to analyze the joint probability of failure at several wells in the aquifer. Results indicate that system failure probability is greater than the largest component failure probability. Correlation between component failure events is greater when the individual wells are closer. Sensitivity of the upper bound on system probability with respect to grid block conductivities is highest along the path the contaminant follows to reach the receptor wells. Furthermore, the probability of failure to contain a plume from escaping site boundaries is analyzed, along with the corresponding sensitivity information. Probability of failure to contain the plume decreases as the well pumping rate increases. The presence of regions of lower conductivity dramatically increases the probability of remediation failure. A careful analysis of aquifer material uncertainty and heterogeneity is vital to the success of groundwater remediation systems.

Hamed, Maged M.; Bedient, Philip B.; Conte, Joel P.

1996-10-01

40

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

41

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

USGS Publications Warehouse

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

Thamke, Joanna N.; Smith, Bruce D.

2014-01-01

42

Contaminant plume configuration and movement: an experimental model  

NASA Astrophysics Data System (ADS)

The relevance of Science and Technology in our daily routines makes it compulsory to educate citizens who have both scientific literacy and scientific knowledge. These will allow them to be intervening citizens in a constantly changing society. Thus, physical and natural sciences are included in school curricula, both in primary and secondary education, with the fundamental aim of developing in the students the skills, attitudes and knowledge needed for the understanding of the planet Earth and its real problems. On the other hand, teaching in Geosciences is more and more based on practical methodologies which use didactic material, sustaining teachers' pedagogical practices and facilitating students' learning tasks suggested on the syllabus defined for each school level. Themes related to exploring the different components of the Hydrological Cycle and themes related to natural environment protection and preservation, namely water resources and soil contamination by industrial and urban sewage are examples of subject matters included on the Portuguese syllabus. These topics motivated the conception and construction of experimental models for the study of the propagation of pollutants on a porous medium. The experimental models allow inducing a horizontal flux of water though different kinds of permeable substances (e.g. sand, silt), with contamination spots on its surface. These experimental activities facilitate the student to understand the flow path of contaminating substances on the saturated zone and to observe the contaminant plume configuration and movement. The activities are explored in a teaching and learning process perspective where the student builds its own knowledge through real question- problem based learning which relate Science, Technology and Society. These activities have been developed in the framework of project ‘Water in the Environment' (CV/PVI/0854) of the POCTI Program (Programa Operacional "Ciência, Tecnologia, Inovação") financed by the Portuguese Fundation for Science and Tecnology and FEDER Program.

Alencoao, A.; Reis, A.; Pereira, M. G.; Liberato, M. L. R.; Caramelo, L.; Amraoui, M.; Amorim, V.

2009-04-01

43

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

44

In situ sequential treatment of a mixed contaminant plume  

NASA Astrophysics Data System (ADS)

Groundwater plumes often contain a mixture of contaminants that cannot easily be remediated in situ using a single technology. The purpose of this research was to evaluate an in situ treatment sequence for the control of a mixed organic plume (chlorinated ethenes and petroleum hydrocarbons) within a Funnel-and-Gate. A shallow plume located in the unconfined aquifer at Alameda Point, CA, was found to contain up to 218,000 ?g/l of cis-1,2 dichloroethene (cDCE), 16,000 ?g/l of vinyl chloride (VC) and <1000 ?g/l of 1,1 dichloroethene (1,1 DCE), trans-1,2 dichloroethene ( trans-1,2 DCE) and trichloroethene (TCE). Total benzene, toluene, ethylbenzene and xylenes (BTEX) concentrations were <10,000 ?g/l. Contaminated groundwater was funneled into a gate, 3.0 m wide, 4.5 m long and 6.0 m deep (keyed into the underlying aquitard) where treatment occurred. The initial gate segment consisted of granular iron, for the reductive dechlorination of the higher chlorinated ethenes. The second segment, the biosparge zone, promoted aerobic biodegradation of petroleum hydrocarbons and any remaining lesser-chlorinated compounds, stimulated by dissolved oxygen (DO) and carbon dioxide (CO 2) additions via an in situ sparge system (CO 2 was used to neutralize the high pH produced from reactions in the iron wall). Groundwater was drawn through the gate by pumping two wells located at the sealed, downgradient, end. Over a 4-month period an estimated 1350 g of cDCE flowed into the treatment gate and the iron wall removed 1230 g, or 91% of the mass. The influent mass of VC was 572 g and the iron wall removed 535 g, corresponding to 94% mass removal. The other chlorinated ethenes had significantly lower influent masses (3 to 108 g) and the iron wall removed the majority of the mass resulting in >96% mass removal for any of the compounds. In spite of these high removal percentages, laboratory column tests indicated that at these levels of chlorinated contaminants, surface saturation of the iron grains likely contributed to lower than expected reaction rates. In the biosparge zone, mass removal of cDCE appeared to occur predominantly by biodegradation (65%) with volatilization (35%) being an important secondary process. The dominant removal process for VC was volatilization (70%) although significant biodegradation was also indicated (30%). Laboratory microcosm results confirmed the potential for aerobic biodegradation of cDCE and VC. When average influent field concentrations for cDCE and VC were 220,000 and 46,000 ?g/l, respectively, the sequential treatment unit removed 99.6% of the total mass and when the influent concentrations decreased to 26,000 and 19,000 ?g/l for cDCE and VC, respectively, >99.9% removal within the treatment gate was attained. BTEX compounds were found to be significantly retarded in the iron treatment zone. Although they did eventually break through the granular iron, and into the gravel transition zone, none of these compounds was detected in the biosparge zone. No noticeable interferences between the anaerobic (reductive) and aerobic parts of the system occurred during testing. The results of this experiment show that in situ treatment sequences are viable, although further work is needed to optimize performance.

Morkin, M.; Devlin, J. F.; Barker, J. F.; Butler, B. J.

2000-10-01

45

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

46

Use of the HydroPunch for groundwater plume delineation: A case study  

SciTech Connect

Historic groundwater investigations at a 300-acre manufacturing facility in Connecticut indicated that solvent and metal contaminated groundwater was migrating off site. To preliminarily investigate off-site groundwater contamination, the collection of discrete-interval groundwater samples using a HydroPunch was attempted in twenty soil borings. The borings were located along three transects perpendicular to the general direction of groundwater flow: (1) three soil borings were located near groundwater monitoring well clusters along the downgradient facility boundary, (2) ten soil borings were located along a road at the approximate midpoint between the facility boundary and a nearby river, and (3) seven soil borings were located along the banks of the river. At each soil boring, collection of the first HydroPunch sample was attempted at ten feet below the water table; sample attempts continued at 3-meter (10-ft) intervals until refusal. Samples were analyzed for volatile organic compounds and selected metals.

Kraemer, C.A. [ICF Kaiser Engineers, Inc., Cheshire, CT (United States); Penn, W.E.; Busa, M.D. [United Technologies Corp., Windsor Locks, CT (United States). Hamilton Standard Div.

1996-12-31

47

Leachate plume delineation and lithologic profiling using surface resistivity in an open municipal solid waste dumpsite, Sri Lanka.  

PubMed

This study presents the use of direct current resistivity techniques (DCRT) for investigation and characterization of leachate-contaminated subsurface environment of an open solid waste dumpsite at Kandy, Sri Lanka. The particular dumpsite has no liner and hence the leachate flows directly to the nearby river via subsurface and surface channels. For the identification of possible subsurface flow paths and the direction of the leachate, DCRT (two-dimensional, three-dimensional and vertical electrical sounding) have been applied. In addition, the physico-chemical parameters such as pH, electrical conductivity (EC), alkalinity, hardness, chloride, chemical oxygen demand (COD) and total organic carbon (TOC) of leachate collected from different points of the solid waste dumping area and leachate drainage channel were analysed. Resistivity data confirmed that the leachate flow is confined to the near surface and no separate plume is observed in the downstream area, which may be due to the contamination distribution in the shallow overburden thickness. The stratigraphy with leachate pockets and leachate plume movements was well demarcated inside the dumpsite via low resistivity zones (1-3 ?m). The recorded EC, alkalinity, hardness and chloride contents in leachate were averaged as 14.13?mS?cm(-1), 3236, 2241 and 320?mg?L(-1), respectively, which confirmed the possible causes for low resistivity values. This study confirms that DCRT can be effectively utilized to assess the subsurface characteristics of the open dumpsites to decide on corridor placement and depth of permeable reactive barriers to reduce the groundwater contamination. PMID:25209886

Wijesekara, Hasintha Rangana; De Silva, Sunethra Nalin; Wijesundara, Dharani Thanuja De Silva; Basnayake, Bendict Francis Antony; Vithanage, Meththika Suharshini

2014-10-01

48

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

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

49

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

E-print Network

1 Studies of Plume Condensation Contamination upon Surfaces of the Terrestrial Planet Finder for the Terrestrial Planet Finder (TPF) mission, one which involves a single spacecraft, and another comprised

50

Modelling reaction front formation and oscillatory behaviour in a contaminant plume  

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

51

Characterization of aquifer relationships by using geochemical techniques for plume delineation  

SciTech Connect

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

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

1994-04-01

52

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

E-print Network

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

Hubbard, Susan

53

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

54

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

NASA Astrophysics Data System (ADS)

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

Mycka, Mateusz; Mendecki, Maciej Jan

2013-09-01

55

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

EPA Science Inventory

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

56

Dense aqueous phase contaminant plume behaviour in porous media near the groundwater table  

Microsoft Academic Search

Physical and numerical model studies were conducted to investigate the behaviour of dense aqueous phase contaminant plumes near the groundwater table. The physical model studies were performed in homogeneous porous media consisting of either glass beads, fine sand, medium sand, or coarse sand. Dense liquids, introduced from sources of different configurations located on top of the porous media, were intercepted

J. H. DANE; O. GUVEN; M. OOSTROM; A. LEIJNSE

57

Ground-water contaminant plume differentiation and source determination using BTEX concentration ratios  

Microsoft Academic Search

Concentration ratios of benzene, toluene, ethylbenzene, and xylenes (BTEX) in ground water can be used for ground-water contaminant plume differentiation and source determination. Computer modeling utilizing BTEX soil-water partitioning coefficients and biodegradation rates shows that hydraulic dispersion, retardation, and biodegradation do not significantly modify the BTEX concentration ratios in ground water, particularly those of ethylbenzene and xylenes. Therefore, the BTEX

Y. Jeffrey Yang; Rick D. Spencer; Mark A. Mersmann; Todd M. Gates

1995-01-01

58

Ground-water contaminant plume differentiation and source determination using BTEX concentration ratios  

SciTech Connect

Concentration ratios of benzene, toluene, ethylbenzene, and xylenes (BTEX) in ground water can be used for ground-water contaminant plume differentiation and source determination. Computer modeling utilizing BTEX soil-water partitioning coefficients and biodegradation rates shows that hydraulic dispersion, retardation, and biodegradation do not significantly modify the BTEX concentration ratios in ground water, particularly those of ethylbenzene and xylenes. Therefore, the BTEX concentration ratios are similar in the contaminant plumes that are derived from a common source or sources of similar BTEX compositions. In the vadose zone, the BTEX concentration ratios in downward-migrating contaminant free-product remain essentially unchanged because of the dynamic nature of soil adsorption and restricted natural soil ventilation. The only significant change in the BTEX concentration ratios occurs in the partitioning between ground water and contaminant free-product as the result of differential BTEX solubilities in water. In the partitioning, benzene/toluene and toluene/ethylbenzene concentration ratios of ground water are 3.6 and 3.3 times greater respectively than the ratios at the source, while the ratios of ethylbenzene and xylenes remain unchanged. The geochemical methods were successfully applied and tested at two sites where multiple ground-water contaminant plumes from different sources were superimposed. The conclusions of geochemical analysis are consistent with the site-specific hydraulic characteristics and facility operation histories.

Yang, Y.J.; Spencer, R.D.; Mersmann, M.A.; Gates, T.M. [T.M. Gates Inc., Milford, OH (United States)

1995-11-01

59

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

60

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

SciTech Connect

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

Dirks, Jaque L.; Nichols, William E.; Wurstner, Signe K.

2004-12-15

61

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

SciTech Connect

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

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

2004-01-01

62

Tracking the origin and dispersion of contaminated sediments transported by rivers draining the Fukushima radioactive contaminant plume  

NASA Astrophysics Data System (ADS)

This study was conducted in several catchments draining the main Fukushima Dai-ichi Power Plant contaminant plume in Fukushima prefecture, Japan. We collected soils and sediment drape deposits (n = 128) and investigated the variation in 137Cs enrichment during five sampling campaigns, conducted every six months, which typically occurred after intense erosive events such as typhoons and snowmelt. We show that upstream contaminated soils are eroded during summer typhoons (June-October) before being exported during the spring snowmelt (March-April). However, this seasonal cycle of sediment dispersion is further complicated by the occurrence of dam releases that may discharge large amounts of contaminants to the coastal plains during the coming years.

Lepage, H.; Evrard, O.; Onda, Y.; Chartin, C.; Lefevre, I.; Sophie, A.; Bonte, P.

2015-03-01

63

Surface and borehole electromagnetic imaging of conducting contaminant plumes  

SciTech Connect

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

Berryman, J. G., LLNL

1998-07-01

64

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

NASA Technical Reports Server (NTRS)

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

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

1973-01-01

65

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

2005-03-01

66

GROUND WATER SAMPLING FOR VERTICAL PROFILING OF CONTAMINANTS  

EPA Science Inventory

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

67

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...

68

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

69

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

70

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.

Larry Lemke

71

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

NASA Astrophysics Data System (ADS)

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 ?g/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.

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

2009-08-01

72

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

2009-08-11

73

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

PubMed

Direct current (DC) resistivity, self potential (SP) and very low frequency electromagnetic (VLF-EM) measurements are carried out to detect the spread of groundwater contamination and to locate possible pathways of leachate plumes, that resulted from an open waste disposal site of Canakkale municipality. There is no proper management of the waste disposal site in which industrial and domestic wastes were improperly dumped. Furthermore, because of the dumpsite is being located at the catchment area borders of a small creek and is being topographically at a high elevation relative to the urban area, the groundwater is expected to be hazardously contaminated. Interpretations of DC resistivity geoelectrical data showed a low resistivity zone (<5 ohm-m), which appears to be a zone, that is fully saturated with leachate from an open dumpsite. The VLF-EM and SP method, support the results of geoelectrical method relating a contaminated zone in the survey area. There is a good correlation between the geophysical investigations and the results of previously collected geochemical and hydrochemical measurements. PMID:17385055

Kaya, M Ali; Ozürlan, Gülçin; Sengül, Ebru

2007-12-01

74

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

75

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

EPA Science Inventory

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

76

J4.4 SOURCE INVERSION FOR CONTAMINANT PLUME DISPERSION IN URBAN ENVIRONMENTS USING BUILDING-RESOLVING SIMULATIONS  

E-print Network

J4.4 SOURCE INVERSION FOR CONTAMINANT PLUME DISPERSION IN URBAN ENVIRONMENTS USING BUILDING problems, however, often include non-linear processes (e.g., dispersion of chemically re- acting substances) or are characterized by non-Gaussian probability distributions (Bennett, 2002). Traditional meth- ods also have

Chow, Fotini Katopodes

77

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

EPA Science Inventory

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

78

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

USGS Publications Warehouse

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

LeBlanc, D. R., (Edited By)

1984-01-01

79

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

PubMed Central

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

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

2007-01-01

80

A New Method of Delineating Three-Dimensional Capture Zones with Models  

Microsoft Academic Search

The Air Force Center for Environmental Excellence operates several groundwater remediation systems at the Massachusetts Military Reservation (MMR). These systems involve multiple extraction and injection wells designed to provide complete or partial hydraulic containment of contaminant plumes. It is important in the design and optimization of these systems to be able to accurately delineate their hydraulic capture zones, which are

John P. Glass; Scott DeHainaut; Rose Forbes

81

In search of plumes: a GPR odyssey in Brazil  

SciTech Connect

Ground penetrating radar (GPR) and geoelectrical surveys have been combined to outline underground contaminant plumes of industrial origin within a petrochemical center in Bahia, Brazil. Such plumes are invading the upper phreatic layers of a regional aquifer system which is being exploited for supplying cities and villages in the region, for industrial activities and even for the population of Salvador, the third largest city in Brazil. Three case studies are presented: two are related to conductive plumes localized beneath a metallurgical plant and an effluent treatment plant and another, a DNAPL plume below a dirt petrochemical unit. Resistivity soundings and transverse profiling were useful for a gross delineation of the aquifer structure and the extent of the contamination. GPR processed sections were employed for refining the subsurface stratigraphy and petrophysics as well as for a more precise mapping of the plume boundaries.

Ulrych, T.J. [Univ. of British Columbia, Vancouver (Canada); Lima, O.A.L. de; Sampaio, E.E.S. [Univ. of Bahia, Salvador (Brazil)

1994-12-31

82

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

PubMed

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

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

2004-09-01

83

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

PubMed

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

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

2012-11-01

84

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

USGS Publications Warehouse

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

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

2014-01-01

85

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. PMID:22115080

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

2011-01-01

86

Developing Conceptual Models of Biodegradation: Lessons Learned From a Long-Term Study of a Crude-Oil Contaminant Plume  

NASA Astrophysics Data System (ADS)

Assessment of natural attenuation as a remedial option requires understanding the long-term fate of contaminant compounds. The development of correct conceptual models of biodegradation requires observations at spatial and temporal scales appropriate for the reactions being measured. For example, the availability of electron acceptors such as solid-phase iron oxides may vary at the cm scale due to aquifer heterogeneities. Characterizing the distribution of these oxides may require small-scale measurements over time scales of tens of years in order to assess their impact on the fate of contaminants. The long-term study of natural attenuation of hydrocarbons in a contaminant plume near Bemidji, MN provides insight into how natural attenuation of hydrocarbons evolves over time. The sandy glacial-outwash aquifer at this USGS Toxic Substances Hydrology research site was contaminated by crude oil in 1979. During the 16 years that data have been collected the shape and extent of the contaminant plume changed as redox reactions, most notably iron reduction, progressed over time. Investigation of the controlling microbial reactions in this system required a systematic and multi-scaled approach. Early indications of plume shrinkage were observed over a time scale of a few years, based on observation well data. These changes were associated with iron reduction near the crude-oil source. The depletion of Fe (III) oxides near the contaminant source caused the dissolved iron concentrations to increase and spread downgradient at a rate of approximately 3 m/year. The zone of maximum benzene, toluene, ethylbenzene, and xylene (BTEX) concentrations has also spread within the anoxic plume. Subsequent analyses of sediment and water, collected at small-scale cm intervals from cores in the contaminant plume, provided insight into the evolution of redox zones at smaller scales. Contaminants, such as ortho-xylene, that appeared to be contained near the oil source based on the larger-scale observation well data, were observed to be migrating in thin layers as the aquifer evolved to methanogenic conditions in narrow zones. The impact of adequately identifying the microbially mediated redox reactions was illustrated with a novel inverse modeling effort (using both the USGS solute transport and biodegradation code BIOMOC and the USGS universal inverse modeling code UCODE) to quantify field-scale hydrocarbon dissolution and biodegradation at the Bemidji site. Extensive historical data compiled at the Bemidji site were used, including 1352 concentration observations from 30 wells and 66 core sections. The simulations reproduced the general large-scale evolution of the plume, but the percent BTEX mass removed from the oil body after 18 years varied significantly, depending on which biodegradation conceptual model was used. The best fit was obtained for the iron-reduction conceptual model, which incorporated the finite availability of Fe (III) in the aquifer and reproduced the field observation that depletion of solid-phase iron resulted in increased downgradient transport of BTEX compounds. The predicted benzene plume 50 years after the spill showed significantly higher concentrations of benzene for the iron-reduction model compared to other conceptual models tested. This study demonstrates that the long-term sustainability of the electron acceptors is key to predicting the ultimate fate of the hydrocarbons. Assessing this evolution of redox processes and developing an adequate conceptual model required observations on multiple spatial scales over the course of many years.

Cozzarelli, I. M.; Esaid, H. I.; Bekins, B. A.; Eganhouse, R. P.; Baedecker, M.

2002-05-01

87

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

88

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

NASA Technical Reports Server (NTRS)

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

Chirivella, J. E.

1975-01-01

89

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

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

90

Assessing the natural attenuation of organic contaminants in aquifers using plume-scale electron and carbon balances: model development with analysis of uncertainty and parameter sensitivity  

NASA Astrophysics Data System (ADS)

A quantitative methodology is described for the field-scale performance assessment of natural attenuation using plume-scale electron and carbon balances. This provides a practical framework for the calculation of global mass balances for contaminant plumes, using mass inputs from the plume source, background groundwater and plume residuals in a simplified box model. Biodegradation processes and reactions included in the analysis are identified from electron acceptors, electron donors and degradation products present in these inputs. Parameter values used in the model are obtained from data acquired during typical site investigation and groundwater monitoring studies for natural attenuation schemes. The approach is evaluated for a UK Permo-Triassic Sandstone aquifer contaminated with a plume of phenolic compounds. Uncertainty in the model predictions and sensitivity to parameter values was assessed by probabilistic modelling using Monte Carlo methods. Sensitivity analyses were compared for different input parameter probability distributions and a base case using fixed parameter values, using an identical conceptual model and data set. Results show that consumption of oxidants by biodegradation is approximately balanced by the production of CH 4 and total dissolved inorganic carbon (TDIC) which is conserved in the plume. Under this condition, either the plume electron or carbon balance can be used to determine contaminant mass loss, which is equivalent to only 4% of the estimated source term. This corresponds to a first order, plume-averaged, half-life of >800 years. The electron balance is particularly sensitive to uncertainty in the source term and dispersive inputs. Reliable historical information on contaminant spillages and detailed site investigation are necessary to accurately characterise the source term. The dispersive influx is sensitive to variability in the plume mixing zone width. Consumption of aqueous oxidants greatly exceeds that of mineral oxidants in the plume, but electron acceptor supply is insufficient to meet the electron donor demand and the plume will grow. The aquifer potential for degradation of these contaminants is limited by high contaminant concentrations and the supply of bioavailable electron acceptors. Natural attenuation will increase only after increased transport and dilution.

Thornton, Steven F.; Lerner, David N.; Banwart, Steven A.

2001-12-01

91

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

Carl Van Faasen

2009-04-01

92

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

USGS Publications Warehouse

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

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

2003-01-01

93

Mercury speciation and mobilization in a wastewater-contaminated groundwater plume  

USGS Publications Warehouse

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

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

2013-01-01

94

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

PubMed

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

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

2013-12-01

95

Techniques of contributing-area delineation for analysis of nonpoint-source contamination of Long Island, New York  

USGS Publications Warehouse

Ninety shallow monitoring wells on Long Island, N.Y., were used to test the hypothesis that the correlation between the detection of volatile organic compounds (VOC's) at a well and explanatory variables representing land use, population density, and hydrogeologic conditions around the well is affected by the size and shape of the area defined as the contributing area. Explanatory variables are quantified through overlay of various specified contributing areas on 1:24 000-scale landuse and population-density geographic information system (GIS) coverages. Four methods of contributing-area delineation were used: (a) centering a circle of selected radius on the well site, (b) orienting a triangular area along the direction of horizontal ground-water flow to the well, (c) generating a shaped based on direction and magnitude of horizontal flow to the well, and (d) generating a shape based on three-dimensional particle pathlines backtracked from the well screen to the water table. The strongest correlations with VOC detections were obtained from circles of 400- to 1 000-meter radius. Improvement in correlation through delineations based on ground-water flow would require geographic overlay on more highly detailed GIS coverages than those used in the study.

Misut, P.

1995-01-01

96

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

97

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...

98

Speciation of iodine isotopes inside and outside of a contaminant plume at the Savannah River Site.  

PubMed

A primary obstacle in understanding the fate and transport of the toxic radionuclide (129)I (a thyroid seeker) is an accurate method to distinguish it from the stable isotope, (127)I, and to quantify the various species at environmentally relevant concentrations (~10(-8) M). A pH-dependent solvent extraction and combustion method was paired with accelerator mass spectrometry (AMS) to measure ambient levels of (129)I/(127)I isotope ratios and iodine speciation (iodide (I(-)), iodate (IO3(-)), and organo-I (OI)) in aquatic systems. The method exhibited an overall uncertainty of 10% or less for I(-) and IO3(-), and less than 30% for OI species concentrations and enabled (129)I measurements as low as 0.001 Bq/L (1 Bq/L=10(-13) M). The method was used to analyze groundwater from the Savannah River Site (SRS), South Carolina, USA, along a pH, redox potential (Eh), and organic carbon gradient (8-60 ?M DOC). The data confirmed that the (129)I/(127)I ratios and species distribution were strongly pH dependent and varied in a systematic manner from the strongly acidic source. While (129)I speciation in plume samples containing total I concentrations >1.7 Bq/L was similar whether measured by AMS or GC-MS ([I(-)]?[IO3(-)]=[OI]), AMS enabled (129)I speciation measurements at much lower concentrations than what was possible with GC-MS. AMS analyses demonstrated that groundwater samples minimally impacted by the plume were still orders of magnitude higher than ambient (129)I concentrations typically found elsewhere in the USA groundwaters and rivers. This is likely due to past atmospheric releases of volatile (129)I species by SRS nuclear reprocessing facilities near the study site. Furthermore, the results confirmed the existence of (129)I not only as I(-), but also as OI and IO3(-) species. PMID:25173764

Schwehr, Kathleen A; Otosaka, Shigeyoshi; Merchel, Silke; Kaplan, Daniel I; Zhang, Saijin; Xu, Chen; Li, Hsiu-Ping; Ho, Yi-Fang; Yeager, Chris M; Santschi, Peter H

2014-11-01

99

A sequential checklist for the assessment of natural attenuation of dissolved petroleum contaminant plumes from leaking underground storage tanks  

SciTech Connect

Estimates of the number of leaking underground storage tanks (UST) are measured in the hundreds of thousands in the United States alone. The discussion in this article largely pertains to the lighter motor fuels which contain aromatic petroleum hydrocarbons. These include benzene, toluene, ethylbenzene and xylenes (BTEX). The occurrence of dissolved BTEX groundwater contaminant plumes is most commonly associated with leaking gasoline USTs. However, their association with other petroleum products is not uncommon. this article and checklist provide guidance for completing UST assessments, which can support the decision-making process presented in the ASTM Emergency Standard Guide. Following the checklist will measure that the initial site assessment results in an accurate and functional characterization of the details and subtleties of the UST Source Impact Zone. This includes evaluating the UST area to identify release pathways for residual contamination in soil and groundwater. Based on the results obtained from the Source Impact Zone Evaluation, natural attenuation can be assessed for its applicability and performance.

De Rose, N. [Langan Engineering and Environmental Services, Inc., Doylestown, PA (United States)

1995-12-31

100

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

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

101

3-D SPECTRAL IP IMAGING: NON-INVASIVE CHARACTERIZATION OF CONTAMINANT PLUMES  

EPA Science Inventory

The objective of this study is to develop a noninvasive tomographic imaging technique,based on the spectral induced-polarization method, to characterize the in-situ distribution of organic and inorganic groundwater contaminants. Recent advances in tomographic imaging, applied to ...

102

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

Microsoft Academic Search

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

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

2001-01-01

103

The Oak Ridge Field Research Center : Advancing Scientific Understanding of the Transportation, Fate, and Remediation of Subsurface Contamination Sources and Plumes  

SciTech Connect

Historical research, development, and testing of nuclear materials across this country resulted in subsurface contamination that has been identified at over 7,000 discrete sites across the U.S. Department of Energy (DOE) complex. With the end of the Cold War threat, DOE has shifted its emphasis to remediation, decommissioning, and decontamination of the immense volumes of contaminated groundwater, sediments, and structures at its sites. DOE currently is responsible for remediating 1.7 trillion gallons of contaminated groundwater, an amount equal to approximately four times the daily U.S. water consumption, and 40 million cubic meters of contaminated soil, enough to fill approximately 17 professional sports stadiums.* DOE also sponsors research intended to improve or develop remediation technologies, especially for difficult, currently intractable contaminants or conditions. The Oak Ridge FRC is representative of some difficult sites, contaminants, and conditions. Buried wastes in contact with a shallow water table have created huge reservoirs of contamination. Rainfall patterns affect the water table level seasonally and over time. Further, the hydrogeology of the area, with its fractures and karst geology, affects the movement of contaminant plumes. Plumes have migrated long distances and to surface discharge points through ill-defined preferred flowpaths created by the fractures and karst conditions. From the standpoint of technical effectiveness, remediation options are limited, especially for contaminated groundwater. Moreover, current remediation practices for the source areas, such as capping, can affect coupled processes that, in turn, may affect the movement of subsurface contaminants in unknown ways. Research conducted at the FRC or with FRC samples therefore promotes understanding of the processes that influence the transport and fate of subsurface contaminants, the effectiveness and long-term consequences of extant remediation options, and the development of improved remediation strategies.

David Watson

2005-04-18

104

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

USGS Publications Warehouse

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

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

2001-01-01

105

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

106

Plume Busters  

NSDL National Science Digital Library

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

Allen Macfarlane

107

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

108

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

PubMed

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

Brusseau, Mark L; Guo, Zhilin

2014-08-01

109

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

NASA Astrophysics Data System (ADS)

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

Brusseau, Mark L.; Guo, Zhilin

2014-08-01

110

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

111

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

USGS Publications Warehouse

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

McCobb, Timothy D.; LeBlanc, Denis R.

2002-01-01

112

Permeable sorptive walls for treatment of hydrophobic organic contaminant plumes in groundwater  

SciTech Connect

Highly hydrophobic contaminants are easily adsorbed from aqueous solutions. Since for many of these compounds sorption increases with increasing organic carbon content natural materials such as bituminous shales and coals may be used in permeable sorptive walls. This, however, only applies if sorption is at equilibrium, which may not always be the case in groundwater treatment using a funnel-and-gate system. In contrast to the natural solids, granular activated carbons (GACs) have very high sorption capacities and reasonably fast sorption kinetics. The laboratory results show that application of GACs (e.g. F100) is economically feasible for in situ removal of polycyclic aromatic hydrocarbons (PAH) from groundwater at a former manufactured gas plant site (MGP). For less sorbing compounds (such as benzene, toluene, xylenes) a combination of adsorption and biodegradation is necessary (i.e. sorptive + reactive treatment).

Grathwohl, P.; Peschik, G. [Univ. of Tuebingen (Germany)

1997-12-31

113

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

114

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

115

Plume Busters  

NSDL National Science Digital Library

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

P. Macfarlane

116

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

117

Long-Term Distribution and Transport of Nitrate and Ammonium Within a Groundwater Sewage Plume, Cape Cod, MA, After Removal of the Contaminant Source.  

NASA Astrophysics Data System (ADS)

Disposal of treated sewage for 60 yrs. onto infiltration beds at a site on Cape Cod, MA produced a groundwater contaminant plume >6 km long. The plume was characterized by an anoxic ammonium-containing core, surrounded by an oxic-suboxic outer zone within the sand and gravel aquifer. In Dec. 1995 the sewage treatment facility ceased operation. A long-term study to characterize the distribution of sewage plume constituents was conducted along a 500 m-long transect (source to 3 yrs. groundwater travel distance). Prior to sewage-disposal cessation, total inorganic N within 30 m vertical profiles decreased from 6.6 moles N/m2 (92% NO3-, 8% NH4+) at the point of discharge to 3.3 moles N/m2 (77% NO3-, 23% NH4+) at the furthest point along the transect. Post-cessation nitrate concentrations increased within the first 6 mo. and then gradually decreased. The nitrate decrease was accompanied by an initial nitrite increase, an indication that denitrification was reducing nitrate after the oxygenated sewage discharge was discontinued. There was also an apparent increase in ammonium concentration in the first 6 mo. after cessation. Previous laboratory experiments on pre-cessation cores showed that nitrification was important in converting sorbed ammonium to nitrate under the sewage beds. However, with the removal of the oxygenated sewage source, nitrification ceased, allowing ammonium to initially increase. This increase was correlated with dissolved organic carbon concentrations within the groundwater. Ammonium concentrations decreased dramatically after a year, but subsequently increased in the core of the plume to pre-cessation levels through mineralization of organic N. Recent laboratory core experiments and extractions show that there is a large pool of sorbed organic carbon, although dissolved organic carbon concentrations have been consistently less than 3 mg/L for 6 yrs. Seven yrs. after cessation of the sewage disposal, there is still a significant amount (0.6 moles N/m2) of fixed inorganic N present in groundwater at the disposal site. It is apparent that sorbed constituents now contribute significantly to the dissolved N pool and natural restoration of the contaminant plume, particularly with respect to N, will likely take several more years.

Repert, D. A.; Smith, R. L.

2002-12-01

118

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

PubMed

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

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

2011-06-15

119

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

120

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

PubMed Central

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

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

2011-01-01

121

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

122

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

123

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

PubMed

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

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

2009-10-01

124

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

125

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

126

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

PubMed Central

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

Gkorezis, Panagiotis; Rineau, Francois; Van Hamme, Jonathan; Daghio, Matteo; Thijs, Sofie; Weyens, Nele

2015-01-01

127

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

PubMed

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

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

2015-01-01

128

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

USGS Publications Warehouse

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

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

2011-01-01

129

Use of superposition and the extended pulse model to evaluate the contaminant transport parameters of variably source-loaded plumes  

E-print Network

not be 19 10, 0 14. 0 3-6 '1 S. o 1 2. 0 1 1. 0 10. 0 Y, cy Z 1000. 0, 10. 0 0. 0 8, 0 O 7. 0 e, o 5. 0 4. 0 $. 0 2. 0 observation points: x(cm) y(cm) C(mt'/L) 1. 18000 0 590 2. 14500 1000 173 3. 12500 1000 157 4. 12000 1500 21 5 1I5000... in the constant source concentration plume. 40 12. 0 1 1. 0 1 0. 0 9. 0 8. 0 7. 0 1-3 1-2 E 6. 0 6. 0 4. 0 3. 0 2. 0 1. 0 observation points: x(cm) y(cm) C(mg/L) 1. 25500 1500 76 2. 24500 500 412 3. 23500 1000 214 4. 22000 1500 64 5. 21500...

Hankins, Donald Wayne

1988-01-01

130

Growth and water and nitrate uptake patterns of grazed and ungrazed desert shrubs growing over a nitrate contamination plume  

Microsoft Academic Search

Two native desert shrubs were evaluated for their growth potential and water and nitrogen uptake patterns over a nitrate-contaminated aquifer at a former uranium ore-processing facility in northeastern Arizona. Sarcobatus vermiculatus and Atriplex canescens are obligate and facultative phreatophytes, respectively, that dominate the local desert plant community. The main questions we addressed were: (1) Are these shrubs able to use

C. McKeon; E. P. Glenn; W. J Waugh; C. Eastoe; F. Jordan; S. G. Nelson

2006-01-01

131

Developing Conceptual Models of Biodegradation: Lessons Learned From a Long-Term Study of a Crude-Oil Contaminant Plume  

Microsoft Academic Search

Assessment of natural attenuation as a remedial option requires understanding the long-term fate of contaminant compounds. The development of correct conceptual models of biodegradation requires observations at spatial and temporal scales appropriate for the reactions being measured. For example, the availability of electron acceptors such as solid-phase iron oxides may vary at the cm scale due to aquifer heterogeneities. Characterizing

I. M. Cozzarelli; H. I. Esaid; B. A. Bekins; R. P. Eganhouse; M. Baedecker

2002-01-01

132

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

PubMed

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

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

2013-05-01

133

Geoelectrical mapping and groundwater contamination  

NASA Astrophysics Data System (ADS)

Specific electrical resistivity of near-surface materials is mainly controlled by the groundwater content and thus reacts extremely sensitive to any change in the ion content. Geoelectric mapping is a well-established, simple, and inexpensive technique for observing areal distributions of apparent specific electrical resistivities. These are a composite result of the true resistivities in the underground, and with some additional information the mapping of apparent resistivities can help to delineate low-resistivity groundwater contaminations, typically observed downstream from sanitary landfills and other waste sites. The presence of other good conductors close to the surface, mainly clays, is a serious noise source and has to be sorted out by supporting observations of conductivities in wells and geoelectric depth soundings. The method may be used to monitor the extent of groundwater contamination at a specific time as well as the change of a contamination plume with time, by carrying out repeated measurements. Examples for both are presented.

Blum, Rainer

134

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

Microsoft Academic Search

This paper quantitatively assesses the spatial extent of modeled contaminated regions resulting from hypothetical airborne agent releases in major urban areas. We compare statistics from a release at several different sites in Washington DC and Chicago using a Gaussian puff model (SCIPUFF, version 1.3, with urban parameter settings) and a building-resolving computational fluid dynamics (CFD) model (FAST3D-CT). For a neutrally

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

2005-01-01

135

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

136

Modelling of thruster plume induced erosion  

Microsoft Academic Search

One source of external induced contamination on the International Space Station (ISS) is thruster plume exhausts. The contamination from these plumes onto ISS sensitive surfaces is due to liquid drops of unreacted or partially reacted propellants. However, the drag acceleration of these particles (drops) from the exhaust gases produces high velocity (~km\\/s) drops that will mechanically damage surfaces in the

John Alred; Paul Boeder; Ron Mikatarian; Courtney Pankop; William Schmidl

2003-01-01

137

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...

138

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

SciTech Connect

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

none,

2013-12-01

139

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

140

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

USGS Publications Warehouse

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

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

2011-01-01

141

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

PubMed

Rapid detection and delineation of contaminants in urban settings is critically important in protecting human health. Cores from trees growing above a plume of contaminated groundwater in Verl, Germany, were collected in 1 day, with subsequent analysis and plume mapping completed over several days. Solid-phase microextraction (SPME) analysis was applied to detect tetrachloroethene (PCE) and trichloroethene (TCE) to below nanogram/liter levels in the transpiration stream of the trees. The tree core concentrations showed a clear areal correlation to the distribution of PCE and TCE in the groundwater. Concentrations in tree cores were lower than the underlying groundwater, as anticipated; however, the tree core water retained the PCE:TCE signature of the underlying groundwater in the urban, populated area. The PCE:TCE ratio can indicate areas of differing degradation activity. Therefore, the phytoscreening analysis was capable not only of mapping the spatial distribution of groundwater contamination but also of delineating zones of potentially differing contaminant sources and degradation. The simplicity of tree coring and the ability to collect a large number of samples in a day with minimal disruption or property damage in the urban setting demonstrates that phytoscreening can be a powerful tool for gaining reconnaissance-level information on groundwater contaminated by chlorinated solvents. The use of SPME decreases the detection level considerably and increases the sensitivity of phytoscreening as an assessment, monitoring, and phytoforensic tool. With rapid, inexpensive, and noninvasive methods of detecting and delineating contaminants underlying homes, as in this case, human health can be better protected through screening of broader areas and with far faster response times. PMID:21848303

Limmer, Matt A; Balouet, Jean-Christophe; Karg, Frank; Vroblesky, Don A; Burken, Joel G

2011-10-01

142

Cone penetrometer testing (CPT) for groundwater contamination  

SciTech Connect

Over the past decade, researchers at the Savannah River Site (SRS) and elsewhere have greatly advanced the knowledge of waste site characterization technologies. As a result, many of the techniques used in the past to investigate waste sites have been replaced by newer technologies, designed to provide greater protection for human health and the environment, greater access to suspected zones of contamination, and more accurate information of subsurface conditions. Determining the most environmentally sound method of assessing a waste unit is a major component of the SRS environmental restoration program. In an effort to understand the distribution and migration of contaminants in the groundwater system, the cone penetrometer investigation of the A/M-Area Southern Sector was implemented. The program incorporated a phased approach toward characterization by first using the CPT to delineate the plume boundary, followed by installing groundwater monitoring wells. The study provided the additional hydrogeologic information necessary to better understand the nature and extent of the contaminant plume (Fig. 1) and the hydrogeologic system in the Southem Sector. This data is essential for the optimal layout of the planned groundwater monitoring well network and recovery system to remediate the aquifers in the area. A number of other test locations were selected in the area during this study for lithologic calibration of the tool and to collect confirmation water samples from the aquifer. Cone penetrometer testing and hydrocone sampling, were performed at 17 sites (Fig. 2). The hydrocone, a tool modification to the CPT, was used to collect four groundwater samples from confined aquifers. These samples were analyzed by SRS laboratories. Elevated levels of chlorinated compounds were detected from these samples and have aided in further delineating the southern sector contaminant plume.

Jordan, J.E.; Van Pelt, R.S.

1993-10-01

143

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

PubMed

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

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

2009-04-01

144

Proactive screening approach for detecting groundwater contaminants along urban streams at the reach-scale.  

PubMed

Here we outline and demonstrate a screening approach for the detection of groundwater contaminants along urban streams within unconsolidated beds. It involves the rapid acquisition of groundwater samples along urban stream reaches at a spacing of about 10 m and from depths of about 25-75 cm below the streambed, with analyses for a suite of potential contaminants. This screening approach may serve two functions: a) providing information for assessing and mitigating the toxicity and eutrophication risks to aquatic ecosystems posed by groundwater contaminants and b) detecting and identifying groundwater contamination in urban settings more rapidly and inexpensively compared to land-based well installations. The screening approach was tested at three urban streams, each affected by a known chlorinated-solvent plume. All three known groundwater plumes were detected and roughly delineated. Multiple, previously unknown, areas or types of groundwater contamination were also identified at each stream. The newly identified contaminants and plumes included petroleum hydrocarbons (BTEX, naphthalene, MTBE), 1,4-dioxane, nitrate and phosphate, road salt, and various metals (including arsenic, cadmium, chromium, copper, lead) at elevated concentrations compared to background values and relevant Canadian water quality guidelines. These findings suggest that this screening approach may be a useful tool for both ecologists performing ecological assessments and stream restorations and for hydrogeologists undertaking groundwater protection activities. Given the numerous contaminants detected, it may be appropriate to apply this technique proactively to better determine the pervasiveness of urban groundwater contaminants, especially along urban streams. PMID:20617839

Roy, James W; Bickerton, Greg

2010-08-15

145

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

2004-01-01

146

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

147

Groundwater Contamination  

NSDL National Science Digital Library

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

Matthew Babcock

148

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

149

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

NASA Astrophysics Data System (ADS)

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

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

2002-02-01

150

Optimized Field Sampling and Monitoring of Airborne Hazardous Transport Plumes; A Geostatistical Simulation Approach  

SciTech Connect

Airborne hazardous plumes inadvertently released during nuclear/chemical/biological incidents are mostly of unknown composition and concentration until measurements are taken of post-accident ground concentrations from plume-ground deposition of constituents. Unfortunately, measurements often are days post-incident and rely on hazardous manned air-vehicle measurements. Before this happens, computational plume migration models are the only source of information on the plume characteristics, constituents, concentrations, directions of travel, ground deposition, etc. A mobile ''lighter than air'' (LTA) system is being developed at Oak Ridge National Laboratory that will be part of the first response in emergency conditions. These interactive and remote unmanned air vehicles will carry light-weight detectors and weather instrumentation to measure the conditions during and after plume release. This requires a cooperative computationally organized, GPS-controlled set of LTA's that self-coordinate around the objectives in an emergency situation in restricted time frames. A critical step before an optimum and cost-effective field sampling and monitoring program proceeds is the collection of data that provides statistically significant information, collected in a reliable and expeditious manner. Efficient aerial arrangements of the detectors taking the data (for active airborne release conditions) are necessary for plume identification, computational 3-dimensional reconstruction, and source distribution functions. This report describes the application of stochastic or geostatistical simulations to delineate the plume for guiding subsequent sampling and monitoring designs. A case study is presented of building digital plume images, based on existing ''hard'' experimental data and ''soft'' preliminary transport modeling results of Prairie Grass Trials Site. Markov Bayes Simulation, a coupled Bayesian/geostatistical methodology, quantitatively combines soft information regarding contaminant location with hard experimental results. Soft information is used to build an initial conceptual image of where contamination is likely to be. As experimental data are collected and analyzed, indicator kriging is used to update the initial conceptual image. The sequential Gaussian simulation is then practiced to make a comparison between the two simulations. Simulated annealing is served as a postprocessor to improve the result of Markov Bayes simulation or sequential Gaussian simulation.

Chen, DI-WEN

2001-11-21

151

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

152

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

153

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

154

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

USGS Publications Warehouse

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

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

2000-01-01

155

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

156

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

PubMed

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

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

2015-03-01

157

Mississippi Plumes  

NSDL National Science Digital Library

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

NASA Goddard Space Flight Center

158

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

SciTech Connect

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

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

2013-07-01

159

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

NASA Astrophysics Data System (ADS)

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

Smith, Matthew

160

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

NASA Technical Reports Server (NTRS)

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

Ruggles, F. H., Jr.

1973-01-01

161

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

PubMed

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

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

2014-06-01

162

River plume patterns and dynamics within the Southern California Bight  

Microsoft Academic Search

Stormwater river plumes are important vectors of marine contaminants and pathogens in the Southern California Bight. Here we report the results of a multi-institution investigation of the river plumes across eight major river systems of southern California. We use in situ water samples from multi-day cruises in combination with MODIS satellite remote sensing, buoy meteorological observations, drifters, and HF radar

J. A. Warricka; P. M. DiGiacomob; S. B. Weisbergc; M. Mengeld; B. H. Jonese; L. Washburnf; E. J. Terrillg; K. L. Farnswortha

163

Isotopic mapping of groundwater perchlorate plumes.  

PubMed

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

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

2012-01-01

164

Testing the plume theory  

Microsoft Academic Search

The physics of low Reynolds number plumes is well understood, and this allows a number of testable predictions to be made about mantle plumes. Mantle plumes are predicted to originate from the core–mantle boundary and consist of a large head, ? 1000 km in diameter followed by a narrower tail. When the head reaches the top of its ascent it flattens to

Ian H. Campbell

2007-01-01

165

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

166

Containment of subsurface contaminants  

DOEpatents

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

Corey, J.C.

1994-09-06

167

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)

Subbottom lake stratification is of interest to hydrology and core site selection, and in delta formation, sediment focusing and periglacial dynamics. Mirror Lake, New Hampshire, within the Hubbard Brook research area, has long been studied, but its subbottom stratification has only been estimated from coring that revealed up to 13 m of gyttja above about 1 m of Late Wisconsin glacial silt. However, the very low water conductivity of 0.002-0.003 S/m allows exceptional penetration of ground-penetrating radar (GPR) signals. Here we discuss several GPR profiles recorded at pulse center frequencies of 60 and 120 MHz along 300-600 m transects that crossed the entire lake in many directions. With care not to misinterpret multiple reflection horizons, the profiles clearly delineate gyttja, till, bedrock horizons, boulder horizons near shore and deltaic deposition. Hyperbolic backscatter in the well-stratified gyttja may be responses from buried logs because they often occur in nests of close, deepening diffractions and much logging historically occurred. Strong local horizons within the gyttja suggest sediment retransport and focusing, as suggested by Davis and Ford in their1982 interpretation of cores. The generally deeper and underlying till is characterized by sections of dense diffractions. In some profile sections internal till horizons appear draped over the bedrock horizons. In others parallel and deep horizons may be responses to bedrock fractures. Using estimated minimal wave speeds based on maximum possible dielectric permittivities calculated from assumed saturated conditions, and partly verified by diffraction interpretation after statics removal, our 60 MHz profiles show gyttja (permittivity no greater than 53) thicknesses of at least 11 m, till (permittivity no greater than 33) thicknesses of at least 25 m and depths to bedrock (Littleton schist) up to 28 m. This till thickness far exceeds the average 4-5 m on the surrounding slopes of the Hubbard Brook watershed. We will return with more powerful and lower frequency antennas during January 2014 to try to find deeper gyttja horizons and more continuity in the bedrock horizons, while improving our positioning by using the ice cover. 60-MHz profile of Mirror Lake showing stratified gyttja, dense diffractions from till, and bedrock. Scales are in meters. Depth scale calibrated for till.

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

2011-12-01

168

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

169

Dust Plume off Mauritania  

NASA Technical Reports Server (NTRS)

A thick plume of dust blew off the coast of Mauritania in western Africa on October 2, 2007. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Aqua satellite observed the dust plume as it headed toward the southwest over the Atlantic Ocean. In this image, the dust varies in color from nearly white to medium tan. The dust plume is easier to see over the dark background of the ocean, but the plume stretches across the land surface to the east, as well. The dust plume's structure is clearest along the coastline, where relatively clear air pockets separate distinct puffs of dust. West of that, individual pillows of dust push together to form a more homogeneous plume. Near its southwest tip, the plume takes on yet another shape, with stripes of pale dust fanning out toward the northwest. Occasional tiny white clouds dot the sky overhead, but skies are otherwise clear.

2007-01-01

170

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

171

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

172

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

USGS Publications Warehouse

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

LeBlanc, Denis R.

1984-01-01

173

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

USGS Publications Warehouse

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

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

1999-01-01

174

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

175

Remediation of DNAPL groundwater contamination at a former landfill abstract  

SciTech Connect

A landfill in western Montana was used for disposal of laboratory waste for a period of five years in the early 1980s. Wastes included chloroform and other chlorinated hydrocarbons which are heavier than water and only slightly soluble in water. These dense non-aqueous phase liquids (DNAPLs) migrated to the water table and eventually created a contaminant plume about three-quarters of a mile long in a residential and commercial area dependent on the aquifer for its water supply. Remediation. efforts to date have consisted of excavation of contaminated soil, treatment of soil on-site, and pumping and treatment of groundwater. An extensive drilling program was undertaken to delineate the extent of ground-water and soil contamination. 75,000 cubic yards of contaminated soil and overburden were excavated and the contaminated soils were treated through volatilization of hydrocarbons. Ground-water pumping in the source area, combined with air stripping has further reduced contaminant concentrations. Replacement water supplies are being installed while remediation continues. A ground-water model has been developed which is being used to predict the effect of remedies. A decision on the final remedy for this site will be made in 1996.

Clark, K.B.; Bucher, B.; Stringer, C. [Maxim Technologies, Inc., Helena/Missoula, MT (United States)

1996-06-01

176

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

177

Delineating alluvial aquifer heterogeneity using resistivity and GPR data.  

PubMed

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

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

2005-01-01

178

COOLING TOWER PLUME MODEL  

EPA Science Inventory

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

179

Stealth Plumes on Io  

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

180

Final report : results of the 2006-2007 investigation of potential contamination at the former CCC/USDA facility in Barnes, Kansas.  

SciTech Connect

The 2006-2007 investigation of carbon tetrachloride and chloroform contamination at Barnes, Kansas, was conducted at the request of the Kansas Department of Health and Environment (KDHE). The Environmental Science Division of Argonne National Laboratory implemented the investigation on behalf of the Commodity Credit Corporation of the U.S. Department of Agriculture (CCC/USDA). The overall goal of the investigation was to establish criteria for monitoring leading to potential site reclassification. The investigation objectives were to (1) determine the hydraulic gradient near the former CCC/USDA facility, (2) delineate the downgradient carbon tetrachloride plume, and (3) design and implement an expanded monitoring network at Barnes (Argonne 2006a).

LaFreniere, L. M.; Environmental Science Division

2008-08-28

181

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

182

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

183

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

PubMed

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

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

2014-03-01

184

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

185

In-situ remediation system and method for contaminated groundwater  

DOEpatents

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

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

1989-05-23

186

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

187

Future Directions and Research Needs for Chlorinated Solvent Plumes  

Microsoft Academic Search

\\u000a Remediation of chlorinated solvent plumes has improved tremendously over the past 25 years. Several treatment and containment\\u000a technologies have been developed and successfully deployed. These technologies have allowed management of plumes for far less\\u000a cost than the earlier presumptive remedy of pump-and-treat. The ability to restore contaminated sites has increased as well,\\u000a reducing health and environmental risks and often allowing

H. F. Stroo; C. H. Ward

188

Modeling Remediation of Chlorinated Solvent Plumes  

Microsoft Academic Search

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

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

189

Funnel-and-gate for in situ groundwater plume containment  

SciTech Connect

At most CERCLA and RCRA sites and numerous other sites, plumes of groundwater contamination emanate from subsurface source zones, commonly DNAPL or LNAPL source zones, where considerable volumes of immiscible organic liquids persist below the water table. Pump-and-treat can provide an effective means of containing hydraulically the dissolved contaminants emanating from these sources; however, at many sites pump-and-treat will have to continue for many decades or longer because the source zones dissipate slowly. Projected long term costs of operation, maintenance, and water disposal or reinjection are therefore large. A new approach for source zone containment or plume control that is more passive than pump-and-treat and that offers considerable potential for long term cost savings has been developed at the University of Waterloo (UW) and is referred to as the fuel-and-gate system (patent pending). In this system low permeability vertical barriers are placed across plumes. Gaps in the barrier allow passage of the plume through the barrier. In the gaps, referred to as gates, a reactive medium is positioned or released so that the plume water is treated while passing through the gates. The reactive medium can be solid phase particles and/or liquid from a controlled release system. The goal is to cause the plume to meet water quality standards on the down gradient side of the funnel-and-gate system and to avoid pumping plume water to surface for treatment.

Smyth, D.J.A.; Cherry, J.A. [Univ. of Waterloo, Ontario (Canada). Waterloo Centre for Groundwater Research; Jowett, R.J. [Waterloo Groundwater Control Technologies Inc., Rockwood, Ontario (Canada)

1994-12-31

190

CHLORINATED SOLVENT PLUME CONTROL  

EPA Science Inventory

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

191

Sulfur plumes off Namibia  

NASA Technical Reports Server (NTRS)

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

2002-01-01

192

River plume patterns and dynamics within the Southern California Bight  

USGS Publications Warehouse

Stormwater river plumes are important vectors of marine contaminants and pathogens in the Southern California Bight. Here we report the results of a multi-institution investigation of the river plumes across eight major river systems of southern California. We use in situ water samples from multi-day cruises in combination with MODIS satellite remote sensing, buoy meteorological observations, drifters, and HF radar current measurements to evaluate the dispersal patterns and dynamics of the freshwater plumes. River discharge was exceptionally episodic, and the majority of storm discharge occurred in a few hours. The combined plume observing techniques revealed that plumes commonly detach from the coast and turn to the left, which is the opposite direction of Coriolis influence. Although initial offshore velocity of the buoyant plumes was ?50 cm/s and was influenced by river discharge inertia (i.e., the direct momentum of the river flux) and buoyancy, subsequent advection of the plumes was largely observed in an alongshore direction and dominated by local winds. Due to the multiple day upwelling wind conditions that commonly follow discharge events, plumes were observed to flow from their respective river mouths to down-coast waters at rates of 20–40 km/d. Lastly, we note that suspended-sediment concentration and beam-attenuation were poorly correlated with plume salinity across and within the sampled plumes (mean r2=0.12 and 0.25, respectively), while colored dissolved organic matter (CDOM) fluorescence was well correlated (mean r2=0.56), suggesting that CDOM may serve as a good tracer of the discharged freshwater in subsequent remote sensing and monitoring efforts of plumes.

Warrick, J.A.; DiGiacomo, P.M.; Weisberg, S.B.; Nezlin, N.P.; Mengel, M.; Jones, B.H.; Ohlmann, J.C.; Washburn, L.; Terrill, E.J.; Farnsworth, K.L.

2007-01-01

193

Stochastic analytical modeling of the biodegradation of steady plumes  

NASA Astrophysics Data System (ADS)

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

Zarlenga, A.; Fiori, A.

2014-02-01

194

Bipropellant rocket exhaust plume analysis on the Galileo spacecraft  

NASA Technical Reports Server (NTRS)

This paper describes efforts to quantify the contaminant flow field produced by 10 N thrust bipropellant rocket engines used on the Galileo spacecraft. The prediction of the composition of the rocket exhaust by conventional techniques is found to be inadequate to explain experimental observations of contaminant deposition on moderately cold (200 K) surfaces. It is hypothesized that low volatility contaminants are formed by chemical reactions which occur on the surfaces. The flow field calculations performed using the direct simulation Monte Carlo method give the expected result that the use of line-of-sight plume shields may have very little effect on the flux of vapor phase contaminant species to a surface, especially if the plume shields are located so close to the engine that the interaction of the plume with the shield is in the transition flow regime. It is shown that significant variations in the exhaust plume composition caused by nonequilibrium effects in the flow field lead to very low concentrations of species which have high molecular weights in the more rarefied regions of the flow field. Recommendations for the design of spacecraft plume shields and further work are made.

Guernsey, C. S.; Mcgregor, R. D.

1986-01-01

195

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

196

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

PubMed

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

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

2008-01-01

197

Biogeochemical evolution of a landfill leachate plume, Norman, Oklahoma  

USGS Publications Warehouse

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

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

2011-01-01

198

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

PubMed

Leachate from municipal landfills can create groundwater contaminant plumes that may last for decades to centuries. The fate of reactive contaminants in leachate-affected aquifers depends on the sustainability of biogeochemical processes affecting contaminant transport. Temporal variations in the configuration of redox zones downgradient from the Norman Landfill were studied for more than a decade. The leachate plume contained elevated concentrations of nonvolatile dissolved organic carbon (NVDOC) (up to 300 mg/L), methane (16 mg/L), ammonium (650 mg/L as N), iron (23 mg/L), chloride (1030 mg/L), and bicarbonate (4270 mg/L). Chemical and isotopic investigations along a 2D plume transect revealed consumption of solid and aqueous electron acceptors in the aquifer, depleting the natural attenuation capacity. Despite the relative recalcitrance of NVDOC to biodegradation, the center of the plume was depleted in sulfate, which reduces the long-term oxidation capacity of the leachate-affected aquifer. Ammonium and methane were attenuated in the aquifer relative to chloride by different processes: ammonium transport was retarded mainly by physical interaction with aquifer solids, whereas the methane plume was truncated largely by oxidation. Studies near plume boundaries revealed temporal variability in constituent concentrations related in part to hydrologic changes at various time scales. The upper boundary of the plume was a particularly active location where redox reactions responded to recharge events and seasonal water-table fluctuations. Accurately describing the biogeochemical processes that affect the transport of contaminants in this landfill-leachate-affected aquifer required understanding the aquifer's geologic and hydrodynamic framework. PMID:21314684

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

2011-01-01

199

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

NASA Astrophysics Data System (ADS)

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

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

2008-10-01

200

Plume primary smoke  

NASA Astrophysics Data System (ADS)

The exhaust from a solid propellant rocket motor usually contains condensed species. These particles, also called 'Primary Smoke', are often prejudicial to missile detectability and to the guidance system. To avoid operational problems it is necessary to know and quantify the effects of particles on all aspects of missile deployment. A brief description of the origin of the primary smoke is given. It continues with details of the interaction between particles and light as function of both particles and light properties (nature, size, wavelength, etc). The effects of particles on plume visibility, attenuation of an optical beam propagated through the plume and the contribution of particles on optical signatures of the plume are also described. Finally, various methods used in NATO countries to quantify the primary smoke effects are discussed.

Chastenet, J. C.

1993-06-01

201

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

E-print Network

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

Alvarez, Pedro J.

202

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...

203

Uncertainty in wellhead protection area delineation due to uncertainty in aquifer parameter values  

NASA Astrophysics Data System (ADS)

The importance of modeling in hydrogeologic investigations has been stressed in a number of studies. Since the applicability of any model is dependent on the type of need and availability of hydrogeological information, a parametric analysis is essential to determine its applicability. This paper presents the results of a parametric analysis conducted to evaluate the effect of data uncertainty on wellhead protection area (WHPA) delineation. The precision of aquifer parameter values is the most important factor in a WHPA delineation process in relation to the model itself. To demonstrate the effect of variable values in a wellfield, we tested modified version of time-related analytical groundwater flow concept using a RESSQC model, which is used for capture zone delineation and to delineate contaminant front for injection wells. The RESSQC model is a modified version of the RESSQ code which was initially designed to only delineate contaminant fronts for injection wells. Field measured aquifer parameters for a shallow aquifer were used in the analysis. The results indicate that great caution must be taken when aquifer parameters such as hydraulic gradient, thickness, transmissivity and porosity are being used for WHPA delineation, since over or under-protection of WHPA can jeopardize the public health. An extended aquifer test and installation of various observation wells in or near different lithologic and depth zones may increase reliability of parameter values.

Bhatt, Kailash

1993-08-01

204

Volcanic Plume Measurements with UAV (Invited)  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

205

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

206

PERMEABLE REACTIVE BARRIERS FOR REMEDIATION OF CONTAMINATED GROUND WATER  

EPA Science Inventory

Permeable reactive barriers (PRB's) are an emerging, alternative in-situ approach for remediating groundwater contamination that combine subsurface fluid flow management with a passive chemical treatment zone. Removal of contaminants from the groundwater plume is achieved by alt...

207

PERFORMANCE MONITORING OF PERMEABLE REACTIVE BARRIERS TO REMEDIATE CONTAMINATED GROUNDWATER  

EPA Science Inventory

Permeable reactive barriers (PRB's) are an emerging, alternative in-situ approach for remediating groundwater contamination that combine subsurface fluid flow management with a passive chemical treatment zone. Removal of contaminants from the groundwater plume is achieved by alt...

208

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

209

COLD WEATHER PLUME STUDY  

EPA Science Inventory

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

210

Enceladus' Water Vapour Plumes  

NASA Technical Reports Server (NTRS)

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

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

2006-01-01

211

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

212

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

213

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

214

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, David C.; Flather, R. A.; Gurney, C.

1996-12-01

215

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

216

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

217

PERMEABLE REACTIVE BARRIER TECHNOLOGIES FOR CONTAMINANT REMEDIATION  

EPA Science Inventory

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

218

Bioremediation of contaminated groundwater  

DOEpatents

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

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

1995-01-01

219

Bioremediation of contaminated groundwater  

DOEpatents

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

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

1995-01-24

220

Large-scale Sedimentary Structures and Contaminant Transport: an Example from Cape Cod, Massachusetts  

NASA Astrophysics Data System (ADS)

A review of 289 borehole logs collected across Cape Cod reveals that two large glacial lakes once covered the peninsula. The older lake, which existed about 19,000 years ago, covered the east-west portion of Cape Cod and deposited clay, silt, and very fine sand across the area. The southern dam of this lake ultimately failed and large drainage channels were carved into the surface of the glaciolacustrine sediments. These eroded lake deposits were subsequently buried by the outwash plains of sand and gravel that make up the surficial geology of today. One of the major drainage channels in the lake deposit surface is located below the Massachusetts Military Reservation (MMR), a 34 square mile facility with >10 known groundwater contaminant plumes. We will present preliminary evidence that the buried paleochannel is exerting a strong control on the transport of several plumes at MMR and thus are critical stratigraphic structures that must be understood and delineated. Although fine-grained sediments are described in borehole logs from the MMR, infering the origin and significance of these deposits is made difficult by local-scale heterogeneities. The existence of the proglacial lake and the extensive, deep drainage channels are only apparent from investigating borehole data across a larger scale. This work illustrates the importance of characterizing the stratigraphic framework beyond the confines of a specific contamination site and further shows the controls that paleochannels filled with high permeability sediments can exert on flow and transport.

Mulligan, A.; Uchupi, E.

2002-05-01

221

43 CFR 3922.40 - Tract delineation.  

Code of Federal Regulations, 2013 CFR

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

2013-10-01

222

43 CFR 3922.40 - Tract delineation.  

Code of Federal Regulations, 2014 CFR

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

2014-10-01

223

43 CFR 3922.40 - Tract delineation.  

Code of Federal Regulations, 2011 CFR

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

2011-10-01

224

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

225

The Green Propellant Infusion Mission Thruster Performance Testing for Plume Diagnostics  

NASA Technical Reports Server (NTRS)

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

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

2014-01-01

226

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

227

Low altitude plume impingement handbook  

NASA Technical Reports Server (NTRS)

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

Smith, Sheldon D.

1991-01-01

228

Ship plume modelling in EOSTAR  

NASA Astrophysics Data System (ADS)

The EOSTAR model aims at assessing the performance of electro-optical (EO) sensors deployed in a maritime surface scenario, by providing operational performance measures (such as detection ranges) and synthetic images. The target library of EOSTAR includes larger surface vessels, for which the exhaust plume may constitute a significant signature element in the thermal wavelength bands. The main steps of the methodology to include thermal signatures of exhaust plumes in EOSTAR are discussed, and illustrative examples demonstrate the impact of the ship's superstructure, the plume exit conditions, and the environment on the plume behavior and signature.

van Iersel, M.; Mack, A.; Degache, M. A. C.; van Eijk, A. M. J.

2014-10-01

229

Z .Journal of Contaminant Hydrology 42 2000 113140 www.elsevier.comrlocaterjconhyd  

E-print Network

spills and waste disposal activities associated with various aircraft maintenance operations. A PCE plume military operations have resulted in chemical contamination of the subsurface soil and associated

Clement, Prabhakar

230

(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

231

Single SCA-plume dynamics  

NASA Astrophysics Data System (ADS)

A fully prognostic prototype of bulk mass-flux convection parameterization is presented. The bulk mass-flux parameterization is formulated by assuming a subgrid-scale system consisting only of a convective plume and environment. Both subcomponents (segments) are assumed to be homogeneous horizontally. This assumption is called the segmentally constant approximation (SCA). The present study introduces this purely geometrical constraint (SCA) into the full nonhydrostatic anelastic system. A continuous-space description of the full system is, thus, replaced by a discretization consisting only of two segments (plume and environment) in the horizontal direction. The resulting discretized system is mathematically equivalent to a 0th order finite volume formulation with the only two finite volumes. The model is presented under a two-dimensional configuration. Interfaces between the plume and the environment segments may either be fixed in time or Lagrangianly advected as two limiting cases. Under this framework, the single-plume dynamics is systematically investigated in a wide phase space of Richardson number, the aspect ratio, and a displacement rate of the plume interfaces relative to the Lagrangian displacement. Advantage of the present model is in evaluating the lateral mixing processes of the plume without invoking an entrainment-detrainment hypothesis. The fractional entrainment-detrainment rate diagnosed from the present model simulations highly varies both over space and time, suggesting a limitation of applying an entrainment-detrainment hypothesis to unsteady plumes, as in the present case, in which circulations of the plume scale dominates over the turbulent mixing process. Furthermore, when the entrainment-plume hypothesis of Morton et al. is adopted for defining the plume-interface displacement rate, the plume continuously expands with time without reaching equilibrium.

Yano, J.-I.; Baizig, Hichem

2012-11-01

232

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

233

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

234

Persistent source influences on the trailing edge of a groundwater plume, and natural attenuation timeframes: the F-Area Savannah River Site.  

PubMed

At the Savannah River Site's F-Area, wastewaters containing radionuclides were disposed into seepage basins for decades. After closure and capping in 1991, the U.S. Department of Energy (DOE) has being monitoring and remediating the groundwater plume. Despite numerous studies of the plume, its persistence for over 20 years has not been well understood. To better understand the plume dynamics, a limited number of deep boreholes were drilled to determine the current plume characteristics. A mixing model was developed to predict plume tritium and nitrate concentrations. We found that the plume trailing edges have emerged for some contaminants, and that contaminant recharge from the basin's vadose zone is still important. The model's estimated time-dependent basin drainage rates combined with dilution from natural recharge successfully predicted plume tritium and nitrate concentrations. This new understanding of source zone influences can help guide science-based remediation, and improve predictions of the natural attenuation timeframes. PMID:22432961

Wan, Jiamin; Tokunaga, Tetsu K; Dong, Wenming; Denham, Miles E; Hubbard, Susan S

2012-04-17

235

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

2010-04-13

236

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

237

Atmospheric chemistry in volcanic plumes  

PubMed Central

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

von Glasow, Roland

2010-01-01

238

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...

239

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

Microsoft Academic Search

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

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

2010-01-01

240

Complex electrical resistance tomography of a subsurface PCE plume  

SciTech Connect

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

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

1996-01-01

241

Ion Engine Plume Interaction Calculations for Prototypical Prometheus 1  

NASA Technical Reports Server (NTRS)

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

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

2005-01-01

242

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

SciTech Connect

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

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

2014-03-02

243

Pulsed Plasma Thruster Contamination  

NASA Technical Reports Server (NTRS)

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

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

1996-01-01

244

The Impact of Well-Field Configuration on Plume Persistence  

NASA Astrophysics Data System (ADS)

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

Guo, Z.; Brusseau, M.

2013-12-01

245

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

246

Estimating Uncertainty in Brain Region Delineations  

PubMed Central

This paper presents a method for estimating uncertainty in MRI-based brain region delineations provided by fully-automated segmentation methods. In large data sets, the uncertainty estimates could be used to detect fully-automated method failures, identify low-quality imaging data, or endow downstream statistical analyses with per-subject uncertainty in derived morphometric measures. Region segmentation is formulated in a statistical inference framework; the probability that a given region-delineating surface accounts for observed image data is quantified by a distribution that takes into account a prior model of plausible region shape and a model of how the region appears in images. Region segmentation consists of finding the maximum a posteriori (MAP) parameters of the delineating surface under this distribution, and segmentation uncertainty is quantified in terms of how sharply peaked the distribution is in the vicinity of the maximum. Uncertainty measures are estimated through Markov Chain Monte Carlo (MCMC) sampling of the distribution in the vicinity of the MAP estimate. Experiments on real and synthetic data show that the uncertainty measures automatically detect when the delineating surface of the entire brain is unclear due to poor image quality or artifact; the experiments cover multiple appearance models to demonstrate the generality of the method. The approach is also general enough to accommodate a wide range of shape models and brain regions. PMID:19694287

Beutner, Karl R.; Prasad, Gautam; Fletcher, Evan; DeCarli, Charles; Carmichael, Owen T.

2010-01-01

247

A simple method for calculating growth rates of petroleum hydrocarbon plumes  

USGS Publications Warehouse

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

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

2005-01-01

248

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

USGS Publications Warehouse

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

Barbaro, Jeffrey R.

2002-01-01

249

Plume measurement system (plumes) calibration experiment. Final technical report  

SciTech Connect

The Measurement of Entrainment and Transport work unit under the Dredging Research Program's Technical Area 1, entitled' Analysis of Dredged Material Placed in Open Water,' developed the PLUmes MEasurement System (PLUMES) to monitor the transport of suspended sediment from dredging and dredged material disposal operations. This acoustic system can monitor nearly synoptically, both horizontally and vertically. To determine the relationship between PLUMES acoustic measurements and suspended sediment concentrations, a laboratory sediment calibration experiment was conducted. The experiment studied acoustic backscattering from particles equivalent in size to those commonly found at dredging and dredged material disposal sites. These particles were suspended in a calibration chamber built for the study. The experiment showed that backscatterance could be predicted and concentrations calculated using Rayleigh scattering theory and an acoustic calibration of PLUMES. This report describes the experiment and the results of the experiment. Data from each calibration run are presented in the Appendices.

Lohrmann, A.; Huhta, C.

1994-08-01

250

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

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

251

Rebound of a coal tar creosote plume following partial source zone treatment with permanganate  

Microsoft Academic Search

The long-term management of dissolved plumes originating from a coal tar creosote source is a technical challenge. For some sites stabilization of the source may be the best practical solution to decrease the contaminant mass loading to the plume and associated off-site migration. At the bench-scale, the deposition of manganese oxides, a permanganate reaction byproduct, has been shown to cause

N. R. Thomson; M. J. Fraser; C. Lamarche; J. F. Barker; S. P. Forsey

2008-01-01

252

Starting plumes and continental break-up  

Microsoft Academic Search

Laboratory studies of fluid dynamic analogs of mantle plumes have led to important advances in our understanding of the life cycle of hotspots. Melting within the large volume heads of starting plumes gives rise to flood basalt provinces, while uplift of the surface above plumes results in horizontal deviatoric stresses that may precipitate considerable continental extension. However, for modern-day plumes

Robert I. Hill

1991-01-01

253

COMPARING AND LINKING PLUMES ACROSS MODELING APPROACHES  

EPA Science Inventory

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

254

Thermal entrainment and melting in mantle plumes  

Microsoft Academic Search

Thermal plumes from the core-mantle boundary (CMB) are thought to cause volcanic hotspots, and starting plumes, or plume ‘heds’, are thought to cause voluminous flood basalt events at the beginning of some hotspot tracks. It has been proposed that starting plumes entrain a large volume fraction of surrounding mantle material as they rise from the CMB to the base of

Dinzia G. Farnetani; Mark A. Richards

1995-01-01

255

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.

256

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

NASA Astrophysics Data System (ADS)

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

Haman, Krzysztof E.; Malinowski, Szymon P.

257

PERFORMANCE MONITORING OF PERMEABLE REACTIVE BARRIERS TO REMEDIATE CONTAMINATED GROUND WATER  

EPA Science Inventory

Permeable reactive barriers (PRB's) are an emerging, alternative in-situ approach for remediating groundwater contamination that combine subsurface fluid flow management with a passive chemical treatment zone. Removal of contaminants from the groundwater plume is achieved by alt...

258

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

2010-04-01

259

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

260

Rocket plume base heating methodology  

NASA Technical Reports Server (NTRS)

A review of radiative transport calculation methods for base heating is presented followed by a description of the current methodology for the Space Shuttle plume radiation predictions and improvements for the Advanced Solid Rocket Booster (ASRB). The calculation methods include empirical methods, the SIRRM code and the forward and reverse Monte Carlo methods. Current plume radiation methods include those used for the Space Shuttle Main Engines and the Solid Rocket Booster (SRB). Methods being developed for the ASRB include changes in plume property prediction methodology and application of the reverse Monte Carlo method in predicting plume radiation models. Results of the prediction methods are compared with experimental measurements on the current SRB and on 1/6-scale motors using both SRB and ASRB propellants. Examples are also presented demonstrating the statistical results available with the reverse Monte Carlo method.

Reardon, John E.; Nelson, H. F.

1993-01-01

261

NSTAR Ion Thruster Plume Impact Assessments  

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

262

Fluctuations in Atmospheric Boundary Layer Plumes  

NASA Astrophysics Data System (ADS)

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

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

2011-11-01

263

Modeling the Hudson River PlumeModeling the Hudson River Plume Forecast plume variabilityForecast plume variability equivalent freshwater distributionequivalent freshwater distribution  

E-print Network

Modeling the Hudson River PlumeModeling the Hudson River Plume Forecast plume variability L CE A N B S E R V A T IO N AB R U U T G E R S N I V E R S I T Y The Hudson River plume and adjacent shelf circulation in theThe Hudson River plume and adjacent shelf circulation in the New York Bight were

Wilkin, John

264

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

NASA Technical Reports Server (NTRS)

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

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

2014-01-01

265

Impacts of transport mechanisms and plume history on tailing of sorbing plumes in heterogeneous porous formations  

NASA Astrophysics Data System (ADS)

This work investigated the impacts of permeability and sorption heterogeneity on contaminant transport in groundwater using simulation experiments designed to elucidate the causes of tailing. The effects of advection, diffusion and sorption mechanisms and plume history were explored. A simple conceptual model consisting of a single inclusion (heterogeneity) of uniform hydraulic conductivity K and sorption distribution coefficient Kd was adopted. The 3D inclusion, shaped as a horizontal oblate ellipsoid of variable thickness, was placed in a homogeneous anisotropic background of different hydraulic conductivity and sorption distribution coefficient. The background represents average K and Kd of a heterogeneous porous formation. A closed-form analytic flow solution for uniform flow past the inclusion was coupled with a numerical transport solution to simulate contaminant migration for a wide range of transport parameters and two distinct source conditions. Over 2600 numerical simulations were performed in parallel. Transport results were presented in terms of travel time distributions at a control plane downstream of the inclusion and used to quantify tailing for a wide range of transport parameters, in order to separate advection-dominated from diffusion-dominated transport regime and to investigate effects of inclusion shape, diffusion, sorption and plume history on tailing.

Maghrebi, Mahdi; Jankovic, Igor; Allen-King, Richelle M.; Rabideau, Alan J.; Kalinovich, Indra; Weissmann, Gary S.

2014-11-01

266

Final report : results of the 2005 investigation of contaminant sources at Agra, Kansas.  

SciTech Connect

The 2005 investigation of contaminant sources at Agra, Kansas, was conducted at the request of the Kansas Department of Health and Environment (KDHE; Gotto 2004). The Environmental Science Division of Argonne National Laboratory implemented the investigation on behalf of the Commodity Credit Corporation of the U.S. Department of Agriculture (CCC/USDA). The investigation was designed to (1) update the conceptual site model and (2) investigate sources of previously identified carbon tetrachloride contamination in groundwater. Six technical objectives were proposed in the ''Work Plan'' (Argonne 2005). The ''Work Plan'' was approved by the KDHE on March 28, 2005 (KDHE 2005). The six objectives were as follows: (1) Determine the current configuration of the carbon tetrachloride plume in the investigation area. (2) Delineate contamination detected in 1998-1999 at the former CCC/USDA facility. (3) Investigate the Pro-Ag Co-op property for evidence of releases of carbon tetrachloride. (4) Investigate the area adjacent to the site of the former retail store for evidence of releases of carbon tetrachloride to the subsurface. (5) Collect data to support the analysis of potential remedial alternatives. (6) Update the inventory of private wells to identify potential downgradient receptors. This report details and interprets the data collected during the 2005 investigation at Agra. The investigation met the objectives defined in the ''Work Plan''.

LaFreniere, L. M.

2006-08-24

267

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

268

[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

269

Delineation of clinical privileges in rehabilitation medicine  

Microsoft Academic Search

Toerge JE, Soni SS, Bleiberg J. Delineation of clinical privileges in rehabilitation medicine. Arch Phys Med Rehabil 2001;82:700-1. The American Academy of Physical Medicine and Rehabilitation (AAPM&R) in 1995 developed a list of 75 clinical privileges (in laundry-list format) that are typical of physiatric practice. This list has been used by some hospitals as a template for physiatric staff privileging.

John E Toerge; Sileen S Soni; Joseph Bleiberg

2001-01-01

270

Image Classification and Delineation of Fragments  

Microsoft Academic Search

\\u000a This paper shows that an algorithm technique involving image classification and valley-edge based image segmentation is a\\u000a highly efficient way of delineating densely packed rock fragments. No earlier work on segmentation of rock fragments has exploited\\u000a these two building blocks for making robust segmentation. Our method has been tested experimentally for different kinds of\\u000a closely packed fragment images which are

Weixing Wang

2005-01-01

271

Active Volcanic Plumes on Io  

NASA Technical Reports Server (NTRS)

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

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

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

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

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

1997-01-01

272

Influence Of Groundwater Discharge On Arsenic Contamination In Sediments  

EPA Science Inventory

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

273

FIELD-DRIVEN APPROACHES TO SUBSURFACE CONTAMINANT TRANSPORT MODELING.  

EPA Science Inventory

Observations from field sites provide a means for prioritizing research activities. In the case of petroleum releases, observations may include spiking of concentration distributions that may be related to water table fluctuation, co-location of contaminant plumes with geochemi...

274

FIELD-DRIVEN APPROACHES TO SUBSURFACE CONTAMINANT TRANSPORT MODELING  

EPA Science Inventory

Observations from field sites provide a means for prioritizing research activities. For petroleum release sites observations include spiking of concentration distributions that may be related to water table fluctuation, co-location of contaminant plumes with geochemical indicat...

275

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

276

Stationary Plasma Thruster Plume Characteristics  

NASA Technical Reports Server (NTRS)

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

Myers, Roger M.; Manzella, David H.

1994-01-01

277

Multiple Factor Analysis and k-Means Clustering-Based Classification of the DOE Groundwater Contaminant Database  

NASA Astrophysics Data System (ADS)

A proper classification of the plume characteristics is critical for selecting the most suitable characterization, monitoring, and remediation technologies. To perform a statistical analysis of the different groundwater plume characteristics, we used the DOE Groundwater Database, including 221 groundwater plumes located at 60 DOE sites. To classify the plume characteristics, we used a multiple factor analysis (MFA), including a principal component analysis (PCA) of quantitative plume characteristics and a multiple correspondence analysis (MCA) of qualitative plume characteristics. The input parameters used for the statistical analysis are: the presence of eight types of contaminant groups—chlorinated hydrocarbons, fuels, explosives, sulfates, nitrates, metals, tritium, and radioisotopes; a number and associations of contaminant groups; a contamination severity index (based on the association of contaminant groups and complexity of remediation); contaminant mass and plume volumes; groundwater depth and velocities; and climatic conditions. The input variables are also partitioned into the active and supplementary plume characteristics. Statistical results include the evaluation of the correlation matrix between the groups of variables and individual plume characteristics. From the results of the MFA, the first four factors can be used to describe the variability of the basic plume characteristics. The contaminant severity index and the number of contaminant groups provide a major contribution to the 1st factor; the types of contaminant groups and carbon tetrachloride concentrations provide the major contribution to the 2nd factor. The contribution of the supplementary data (climate and plume depth and velocity) is insignificant. The presence of radioactive contaminants is mostly related to the 1st factor; the presence of sulfates, and to a lesser degree the presence of nitrates and metals, is related to the 2nd factor. The strongest relationship is, as expected, between the types of contaminant groups and the contamination severity. The relationships between contaminant groups and the plume depth and velocity, and contaminant groups and climate are weak, and there is no a significant relationship with the plume volumes. To visualize the contribution of different factors, the results of MFA calculations are presented using two- and three-dimensional maps. Using the first four factors for the basic plume characteristics, a k-means cluster analysis was applied to classify the plumes into respective clusters. These results can be used to plan characterization, monitoring, and modeling of contaminant behavior at contaminated sites, and to design appropriate remediation technologies.

Faybishenko, B.; Hazen, T. C.

2009-12-01

278

Plumes, plateaux and congestion in subduction zones  

NASA Astrophysics Data System (ADS)

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

Moresi, Louis; Betts, Peter; Miller, Meghan; Willis, David

2014-05-01

279

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

280

Mobile Bay turbidity plume study  

NASA Technical Reports Server (NTRS)

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

Crozier, G. F.

1976-01-01

281

Exhaust Nozzle Plume and Shock Wave Interaction  

NASA Technical Reports Server (NTRS)

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

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

2013-01-01

282

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...

283

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

284

Complex electrical resistance tomography of a subsurface PCE plume  

SciTech Connect

A controlled experiment was conducted to evaluate the performance of complex electrical resistivity tomography (CERT) for detecting and delineating free product dense non aqueous phase liquid (DNAPL) in the subsurface. One hundred ninety liters of PCE were released at a rate of 2 liters per hour from a point 0.5 m below ground surface. The spill was conducted within a double walled tank where saturated layers of sand, bentonite and a sand/bentonite mixture were installed. Complex electrical resistance measurements were performed from 4 vertical electrode arrays, each with 10 electrodes spaced between 3 m and 0.5 m depth. Data were taken before the release, several times during, and then after the PCE was released. Magnitude and phase were measured at 1 and 64 Hz. Data from before the release were compared with those during the release for the purpose of imaging the changes in conductivity resulting from the plume. Conductivity difference tomographs showed a decrease in electrical conductivity as the DNAPL penetrated the soil. A pancake-shaped anomaly developed on the top of a bentonite layer at 2 m depth. The anomaly grew in magnitude and extent during the release and borehole television surveys data confirmed the anomaly to be free-product PCE whose downward migration was stopped by the low permeability clay. The tomographs clearly delineated the plume as a resistive anomaly. Images showing phase changes caused by the spill are also presented. The phase changes at 64 Hz suggest that the DNAPL spill increased the induced polarization (IP) effect of the clay layers.

Ramirez, A.; Daily W. [Lawrence Livermore National Laboratory, CA (United States); LaBrecque, D. [Univ. of Arizona, Tucson, AZ (United States)

1996-11-01

285

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

NSDL National Science Digital Library

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

286

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

287

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...

288

Plasma plume MHD power generator and method  

DOEpatents

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

Hammer, J.H.

1993-08-10

289

Arsenic cycling in hydrocarbon plumes: secondary effects of natural attenuation  

USGS Publications Warehouse

Monitored natural attenuation is widely applied as a remediation strategy at hydrocarbon spill sites. Natural attenuation relies on biodegradation of hydrocarbons coupled with reduction of electron acceptors, including solid phase ferric iron (Fe(III)). Because arsenic (As) adsorbs to Fe-hydroxides, a potential secondary effect of natural attenuation of hydrocarbons coupled with Fe(III) reduction is a release of naturally occurring As to groundwater. At a crude-oil-contaminated aquifer near Bemidji, Minnesota, anaerobic biodegradation of hydrocarbons coupled to Fe(III) reduction has been well documented. We collected groundwater samples at the site annually from 2009 to 2013 to examine if As is released to groundwater and, if so, to document relationships between As and Fe inside and outside of the dissolved hydrocarbon plume. Arsenic concentrations in groundwater in the plume reached 230?µg/L, whereas groundwater outside the plume contained less than 5?µg/L As. Combined with previous data from the Bemidji site, our results suggest that (1) naturally occurring As is associated with Fe-hydroxides present in the glacially derived aquifer sediments; (2) introduction of hydrocarbons results in reduction of Fe-hydroxides, releasing As and Fe to groundwater; (3) at the leading edge of the plume, As and Fe are removed from groundwater and retained on sediments; and (4) downgradient from the plume, patterns of As and Fe in groundwater are similar to background. We develop a conceptual model of secondary As release due to natural attenuation of hydrocarbons that can be applied to other sites where an influx of biodegradable organic carbon promotes Fe(III) reduction.

Cozzarelli, Isabelle M.; Schreiber, Madeline E.; Erickson, Melinda L.; Ziegler, Brady A.

2015-01-01

290

Biogeochemical characterisation of a coal tar distillate plume.  

PubMed

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

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

2001-12-15

291

Plume mechanics and stratocumulus convection  

NASA Technical Reports Server (NTRS)

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

Hanson, Howard P.

1990-01-01

292

Smoke Plume Over Eastern Canada  

NASA Technical Reports Server (NTRS)

In late May, a massive smoke plume hundreds of kilometers across blew eastward over New Brunswick toward the Atlantic Ocean. On May 26, 2007, the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite captured this image at 11:40 a.m. local time. By the time MODIS took this picture, the smoke appeared to have completely detached itself from the source, a large fire burning in southwestern Quebec, beyond the western edge of this image. In this image, the smoke appears as a gray-beige opaque mass with fuzzy, translucent edges. The plume is thickest in the southwest and diminishes toward the northeast. Just southwest of the plume is a red outline indicating a hotspot an area where MODIS detected anomalously warm surface temperatures, such as those resulting from fires. This hotspot, however, is not the source for this smoke plume. According to a bulletin from the National Oceanic and Atmospheric Administration, the southwestern Quebec fire was the source. According to reports from the Canadian Interagency Forest Fire Centre on May 29, that fire was estimated at 63,211 hectares (156,197 acres), and it was classified as 'being held.' At the same time, more than 20 wildfires burned in Quebec, news sources reported, and firefighters from other Canadian provinces and the United States had been brought in to provide reinforcements for the area's firefighters.

2007-01-01

293

Applying Contamination Modelling to Spacecraft Propulsion Systems Designs and Operations  

NASA Technical Reports Server (NTRS)

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

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

2000-01-01

294

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

2008-02-19

295

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

Microsoft Academic Search

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

R Kosonen; H Koskela; P Saarinen

296

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...

297

PROBABILITY OF PLUME INTERCEPTION USING CONDITIONAL SIMULATION OF HYDRAULIC HEAD AND INVERSE MODELING  

EPA Science Inventory

A procedure to estimate the probability of intercepting a contaminant groundwater plume for monitoring network design has been developed and demonstrated. he objective of the procedure is to use all available infomration in a method that accounts for the heterogeneity of the aqui...

298

Instability of waste plumes adsorbed on iron oxide in soils  

SciTech Connect

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

Gruber, J.

1987-03-01

299

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

300

Tracing subsurface migration of contaminants from an abandoned municipal landfill  

Microsoft Academic Search

This paper aims at determining of inorganic leachate contamination for a capped unsanitary landfill in the absence of hydrogeological\\u000a data. The 2D geoelectrical resistivity imaging, soil physicochemical characterization, and surface water analysis were used\\u000a to determine contamination load and extent of selective heavy metal contamination underneath the landfill. The positions of\\u000a the contaminated subsoil and groundwater were successfully delineated in

E. A. Rahim Bahaa-eldin; I. Yusoff; S. Abdul Rahim; W. Y. Wan Zuhairi; M. R. Abdul Ghani

2011-01-01

301

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

USGS Publications Warehouse

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

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

2012-01-01

302

Compositional differentiation of Enceladus' plume  

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

303

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

304

Costs of groundwater contamination  

SciTech Connect

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

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

1990-01-01

305

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

306

Irritants in cigarette smoke plumes.  

PubMed Central

Concentrations of the irritants formaldehyde and acrolein in side stream cigarette smoke plumes are up to three orders of magnitude above occupational limits, readily accounting for eye and nasal irritation. "Low-tar" cigarettes appear at least as irritating as other cigarettes. More than half the irritant is associated with the particulate phase of the smoke, permitting deposition throughout the entire respiratory tract and raising the issue of whether formaldehyde in smoke is associated with bronchial cancer. PMID:7125032

Ayer, H E; Yeager, D W

1982-01-01

307

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

USGS Publications Warehouse

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

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

1989-01-01

308

The ice plumes of Europa  

NASA Astrophysics Data System (ADS)

It is of extreme interest to NASA and the scientific community that evidence has been found for plumes of water ice venting from the polar regions of Europa (Roth et al 2014) - spectroscopic detection of off-limb line emission from the dissociation products of water. We were awarded Cycle 21 time to seek direct images of the Europa exosphere, including Enceladus-like plumes if present, basing our study on FUV images of Europa as it transits the smooth face of Jupiter. We also obtained a necessary FUV image of Europa out of transit. These observations provide additional evidence for the presence of ice plumes on Europa. Here, we propose to augment our previous imaging work and to seek an initial, efficient characterization of off-limb emission as Europa orbits Jupiter. Such images provide sensitive flux and column density limits, with exceptional spatial resolution. In transit, our strategy can place firm limits on, or measurements of, absorbing columns, their distribution with altitude above the surface of Europa, and constrain their wavelength dependence and hence composition. Out of transit, geometrical and surface brightness considerations can help us distinguish between continuum FUV emission from forward- or back-scattering, from line emission, or, though we might prefer otherwise, from more subtle instrumental artifacts than hitherto understood. If the ice fountains of Europa arise from the deep ocean, we have gained access to probably the most astrobiologically interesting location in the Solar System.

Sparks, William

2014-10-01

309

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

PubMed

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

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

2007-07-17

310

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...

311

Innovative Strategy For Long Term Monitoring Of Metal And Radionuclide Plumes  

SciTech Connect

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

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

2014-01-08

312

On the accuracy of PLIF measurements in slender plumes  

NASA Astrophysics Data System (ADS)

The purpose of this article was to assess the measurement uncertainty of the planar laser-induced fluorescence (PLIF) method and, as much as possible, to devise corrections for predictable biases. More specifically, we considered the measurement of concentration maps in cross sections parallel to and normal to the axis of a slender plume containing Rhodamine 6G as a passive scalar tracer and transported by a turbulent shear flow. In addition to previously examined sources of error related to PLIF, we also investigated several unexplored ones. First, we demonstrated that errors would arise if the laser sheet thickness was comparable to or larger than the thickness of the instantaneous plume. We then investigated the effect of secondary fluorescence, which was attributed to absorption and re-emission of primary fluorescence by dye both within and outside the laser sheet. We found that, if uncorrected, this effect would contaminate the calibration as well as the instantaneous concentration measurements of the plume, and proposed methods for the correction of these errors and for identifying the instantaneous boundaries of the in-sheet dye regions.

Vanderwel, Christina; Tavoularis, Stavros

2014-08-01

313

Seismically imaging the Afar plume  

NASA Astrophysics Data System (ADS)

Plume related flood basalt volcanism in Ethiopia has long been cited to have instigated continental breakup in northeast Africa. However, to date seismic images of the mantle beneath the region have not produced conclusive evidence of a plume-like structure. As a result the nature and even existence of a plume in the region and its role in rift initiation and continental rupture are debated. Previous seismic studies using regional deployments of sensors in East-Africa show that low seismic velocities underlie northeast Africa, but their resolution is limited to the top 200-300km of the Earth. Thus, the connection between the low velocities in the uppermost mantle and those imaged in global studies in the lower mantle is unclear. We have combined new data from Afar, Ethiopia with 6 other regional experiments and global network stations across Ethiopia, Eritrea, Djibouti and Yemen, to produce high-resolution models of upper mantle P- and S- wave velocities to the base of the transition zone. Relative travel time tomographic inversions show that the top 100km is dominated by focussed low velocity zones, likely associated with melt in the lithosphere/uppermost asthenosphere. Below these depths a broad SW-NE oriented sheet like upwelling extends down to the top of the transition zone. Within the transition zone two focussed sharp-sided low velocity regions exist: one beneath the Western Ethiopian plateau outside the rift valley, and the other beneath the Afar depression. The nature of the transition zone anomalies suggests that small upwellings may rise from a broader low velocity plume-like feature in the lower mantle. This interpretation is supported by numerical and analogue experiments that suggest the 660km phase change and viscosity jump may impede flow from the lower to upper mantle creating a thermal boundary layer at the base of the transition zone. This allows smaller, secondary upwellings to initiate and rise to the surface. Our images of secondary upwellings suggest that there is no evidence for a plume in the classical sense (i.e. a narrow conduit). Instead, we propose that secondary upwellings rise from the base of the transition zone and connect in the upper mantle. This coupled with measurements of seismic anisotropy suggest that mantle material flows northeast towards Arabia, and may be responsible for the dramatic dynamic topography observed in northeast Africa and western Arabia.

Hammond, J. O.; Kendall, J. M.; Bastow, I. D.; Stuart, G. W.; Keir, D.; Ayele, A.; Ogubazghi, G.; Ebinger, C. J.; Belachew, M.

2011-12-01

314

Mantle plumes on Venus revisited  

NASA Technical Reports Server (NTRS)

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

Kiefer, Walter S.

1992-01-01

315

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

316

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

NASA Astrophysics Data System (ADS)

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

Theroude, C.; Scremin, G.; Wartelski

2011-08-01

317

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

2006-05-01

318

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

USGS Publications Warehouse

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

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

2001-01-01

319

Modelling the fate of the Tijuana River discharge plume  

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

320

Space shuttle main engine plume radiation model  

NASA Technical Reports Server (NTRS)

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

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

1978-01-01

321

Field determination of dispersivity of comingling plumes  

E-print Network

. This gives a wor king basis to extend the same style analysis to a real mass distribution. The real analysis is carried out upon a landfill leachate plume emanating from the Babylon Landfill occurring in Long Island, New York. The plume is described... of Iteration Diagrams Ideal Plume Parameter Determination. Sensitivity Analysis for Iteration Diagrams. PHYSICAL FRAMEWORK FOR REAL ANALYSIS. Description of Landfill. Chemistry of Leachate. Hydrogeology of Babylon Site Well Control Three Dimensional...

Kelley, Van Alan

1985-01-01

322

Measuring Total Dissolved Gas Pressure at a Petroleum Plume Site  

NASA Astrophysics Data System (ADS)

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

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

2009-05-01

323

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

324

In situ bioremediation of trichloroethy lene- contaminated water by a resting-cell methanotrophic microbial filter  

Microsoft Academic Search

An in situ microbial filter technology is being tested and deve­ loped for remediating migrating subsurface plumes contaminated with low concentrations of trichloroethy lene (TCE). The current focus is the establishment of a replenishable bioactive zone (catalytic filter) along expanding plume boundaries by the injection of a representative methano­ trophic bacterium, Methylosinus trichosporium OB3b. This microbial filter strategy has been

R. T. TAYLOR; M. L. HANNA; N. N. SHAH; D. R. SHONNARD; J. P. KNEZOVICH; M. C. JOVANOVICH

1994-01-01

325

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

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

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

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

328

MinE 422:Prediction of air contaminates from a point source  

E-print Network

height of stack (h) Gaussian Dispersion Model #12;3 y = standard deviation of the plume's probability1 MinE 422:Prediction of air contaminates from a point source · Dispersion of contaminates. #12;2 Dispersion of a Contaminant from an Elevated Point Source Y (X, Y, 0) (X, Y, Z) H (X, 0, 0) h h

Boisvert, Jeff

329

Remediation of Uranium-contaminated Groundwater by Sorption onto Hydroxyapatite Derived  

E-print Network

in several Department of Energy (DOE) sites have been severely contaminated with radionuclides. Due to itsRemediation of Uranium-contaminated Groundwater by Sorption onto Hydroxyapatite Derived from for remediating U(VI)-contaminated groundwater plumes. Keywords U(VI) . Hydroxyapatite . Permeable reactive

Clement, Prabhakar

330

Complexity of Groundwater Contaminants at DOE Sites  

SciTech Connect

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

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

2010-12-03

331

Space shuttle contamination due to backflow from control motor exhaust  

NASA Technical Reports Server (NTRS)

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

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

1976-01-01

332

Automatic delineation of geomorphological slope units  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

333

Structure and dynamics of the Columbia River tidal plume front  

Microsoft Academic Search

Time-dependent buoyant plumes form at the outflow of tidally dominated estuaries. When estuary discharge velocity exceeds plume internal wave speed c, a sharp front forms at the plume's leading edge that expands from the time-dependent source. Using observations of the Columbia River tidal plume from multiple tidal cycles we characterize time-evolving plume structure and quantify front speed Uf, plume internal

Levi F. Kilcher; Jonathan D. Nash

2010-01-01

334

The plume variation at Enceladus  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

335

Numerical Simulation of Rarefied Plume Flow Exhausting from a Small Nozzle  

NASA Astrophysics Data System (ADS)

This paper describes the numerical studies of a rarefied plume flow expanding through a nozzle into a vacuum, especially focusing on investigating the nozzle performance, the angular distributions of molecular flux in the nozzle plume and the influence of the backflow contamination for the variation of nozzle geometries and gas/surface interaction models. The direct simulation Monte Carlo (DSMC) method is employed for determining inside the nozzle and in the nozzle plume. The simulation results indicate that the half-angle of the diverging section in the highest thrust coefficient is 25° - 30° and this value varies with the expansion ratio of the nozzle. The descent of the half-angle brings about the increase of the molecules that are scattered in the backflow region.

Hyakutake, Toru; Yamamoto, Kyoji

2003-05-01

336

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

NASA Technical Reports Server (NTRS)

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

Pencil, Eric J.

1994-01-01

337

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

338

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

339

Distant Plume from Puhi-o-Kalaikini  

USGS Multimedia Gallery

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

340

Atmospheric chemistry of an Antarctic volcanic plume  

Microsoft Academic Search

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

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

2010-01-01

341

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...

342

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

EPA Science Inventory

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

343

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

344

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

E-print Network

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

Watson, Samuel Jewell

1997-01-01

345

MODELING PLUMES IN SMALL STREAMS  

EPA Science Inventory

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

346

Low-buoyancy thermochemical plumes resolve controversy of classical mantle plume concept.  

PubMed

The Earth's biggest magmatic events are believed to originate from massive melting when hot mantle plumes rising from the lowermost mantle reach the base of the lithosphere. Classical models predict large plume heads that cause kilometre-scale surface uplift, and narrow (100?km radius) plume tails that remain in the mantle after the plume head spreads below the lithosphere. However, in many cases, such uplifts and narrow plume tails are not observed. Here using numerical models, we show that the issue can be resolved if major mantle plumes contain up to 15-20% of recycled oceanic crust in a form of dense eclogite, which drastically decreases their buoyancy and makes it depth dependent. We demonstrate that, despite their low buoyancy, large enough thermochemical plumes can rise through the whole mantle causing only negligible surface uplift. Their tails are bulky (>200?km radius) and remain in the upper mantle for 100 millions of years. PMID:25907970

Dannberg, Juliane; Sobolev, Stephan V

2015-01-01

347

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

348

18 CFR 415.43 - Mapped and unmapped delineations.  

Code of Federal Regulations, 2013 CFR

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

2013-04-01

349

18 CFR 415.43 - Mapped and unmapped delineations.  

Code of Federal Regulations, 2011 CFR

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

2011-04-01

350

18 CFR 415.43 - Mapped and unmapped delineations.  

Code of Federal Regulations, 2014 CFR

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

2014-04-01

351

18 CFR 415.43 - Mapped and unmapped delineations.  

Code of Federal Regulations, 2012 CFR

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

2012-04-01

352

10. Photocopy of map (from Benicia Historical Society) Delineator unknown ...  

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

10. Photocopy of map (from Benicia Historical Society) Delineator unknown May 1, 1894, revised to Mar. 27, 1918 'MAP OF BENICIA ARSENAL RESERVATION' - Benicia Arsenal, Benicia Industrial Park, Benicia, Solano County, CA

353

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

354

Identification and delineation of urbanized areas using Landsat data  

NASA Technical Reports Server (NTRS)

The use of Landsat data to delineate urban boundaries in Standard Metropolitan Statistical Areas is considered. The project, which is being conducted by the Census-Urbanized Area Application System Verification program, seeks to develop processing techniques and output products that meet urban fringe delineation requirements. A processing approach which will use an interactive processing system to produce digital enhancement and classification results is described.

Dietrich, D. L.; Lachowski, H. M.; Christenson, J. W.

1978-01-01

355

Galileo observations of volcanic plumes on Io  

NASA Astrophysics Data System (ADS)

Io's volcanic plumes erupt in a dazzling variety of sizes, shapes, colors and opacities. In general, the plumes fall into two classes, representing distinct source gas temperatures. Most of the Galileo imaging observations were of the smaller, more numerous Prometheus-type plumes that are produced when hot flows of silicate lava impinge on volatile surface ices of SO 2. Few detections were made of the giant, Pele-type plumes that vent high temperature, sulfur-rich gases from the interior of Io; this was partly because of the insensitivity of Galileo's camera to ultraviolet wavelengths. Both gas and dust spout from plumes of each class. Favorably located gas plumes were detected during eclipse, when Io was in Jupiter's shadow. Dense dust columns were imaged in daylight above several Prometheus-type eruptions, reaching heights typically less than 100 km. Comparisons between eclipse observations, sunlit images, and the record of surface changes show that these optically thick dust columns are much smaller in stature than the corresponding gas plumes but are adequate to produce the observed surface deposits. Mie scattering calculations suggest that these conspicuous dust plumes are made up of coarse grained "ash" particles with radii on the order of 100 nm, and total masses on the order of 10 6 kg per plume. Long exposure images of Thor in sunlight show a faint outer envelope apparently populated by particles small enough to be carried along with the gas flow, perhaps formed by condensation of sulfurous "snowflakes" as suggested by the plasma instrumentation aboard Galileo as it flew through Thor's plume [Frank, L.A., Paterson, W.R., 2002. J. Geophys. Res. (Space Phys.) 107, doi:10.1029/2002JA009240. 31-1]. If so, the total mass of these fine, nearly invisible particles may be comparable to the mass of the gas, and could account for much of Io's rapid resurfacing.

Geissler, P. E.; McMillan, M. T.

2008-10-01

356

Galileo observations of volcanic plumes on Io  

USGS Publications Warehouse

Io's volcanic plumes erupt in a dazzling variety of sizes, shapes, colors and opacities. In general, the plumes fall into two classes, representing distinct source gas temperatures. Most of the Galileo imaging observations were of the smaller, more numerous Prometheus-type plumes that are produced when hot flows of silicate lava impinge on volatile surface ices of SO2. Few detections were made of the giant, Pele-type plumes that vent high temperature, sulfur-rich gases from the interior of Io; this was partly because of the insensitivity of Galileo's camera to ultraviolet wavelengths. Both gas and dust spout from plumes of each class. Favorably located gas plumes were detected during eclipse, when Io was in Jupiter's shadow. Dense dust columns were imaged in daylight above several Prometheus-type eruptions, reaching heights typically less than 100 km. Comparisons between eclipse observations, sunlit images, and the record of surface changes show that these optically thick dust columns are much smaller in stature than the corresponding gas plumes but are adequate to produce the observed surface deposits. Mie scattering calculations suggest that these conspicuous dust plumes are made up of coarse grained 'ash' particles with radii on the order of 100 nm, and total masses on the order of 106 kg per plume. Long exposure images of Thor in sunlight show a faint outer envelope apparently populated by particles small enough to be carried along with the gas flow, perhaps formed by condensation of sulfurous 'snowflakes' as suggested by the plasma instrumentation aboard Galileo as it flew through Thor's plume [Frank, L.A., Paterson, W.R., 2002. J. Geophys. Res. (Space Phys.) 107, doi:10.1029/2002JA009240. 31-1]. If so, the total mass of these fine, nearly invisible particles may be comparable to the mass of the gas, and could account for much of Io's rapid resurfacing.

Geissler, P.E.; McMillan, M.T.

2008-01-01

357

Back contamination.  

NASA Technical Reports Server (NTRS)

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

Phillips, G. B.

1971-01-01

358

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

359

Delinating Thermohaline Double-Diffusive Rayleigh Regimes  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

360

Geochemical evolution of highly alkaline and saline tank waste plumes during seepage through vadose zone sediments 1  

NASA Astrophysics Data System (ADS)

Leakage of highly saline and alkaline radioactive waste from storage tanks into underlying sediments is a serious environmental problem at the Hanford Site in Washington State. This study focuses on geochemical evolution of tank waste plumes resulting from interactions between the waste solution and sediment. A synthetic tank waste solution was infused into unsaturated Hanford sediment columns (0.2, 0.6, and 2 m) maintained at 70°C to simulate the field contamination process. Spatially and temporally resolved geochemical profiles of the waste plume were obtained. Thorough OH - neutralization (from an initial pH 14 down to 6.3) was observed. Three broad zones of pore solutions were identified to categorize the dominant geochemical reactions: the silicate dissolution zone (pH > 10), pH-neutralized zone (pH 10 to 6.5), and displaced native sediment pore water (pH 6.5 to 8). Elevated concentrations of Si, Fe, and K in plume fluids and their depleted concentrations in plume sediments reflected dissolution of primary minerals within the silicate dissolution zone. The very high Na concentrations in the waste solution resulted in rapid and complete cation exchange, reflected in high concentrations of Ca and Mg at the plume front. The plume-sediment profiles also showed deposition of hydrated solids and carbonates. Fair correspondence was obtained between these results and analyses of field borehole samples from a waste plume at the Hanford Site. Results of this study provide a well-defined framework for understanding waste plumes in the more complex field setting and for understanding geochemical factors controlling transport of contaminant species carried in waste solutions that leaked from single-shell storage tanks in the past.

Wan, Jiamin; Tokunaga, Tetsu K.; Larsen, Joern T.; Serne, R. Jeff

2004-02-01

361

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

SciTech Connect

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

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

1997-12-31

362

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

SciTech Connect

A light nonaqueous phase liquid (LNAPL) ground water contaminant plume has been discovered by purely geophysical means at the former Wurtsmith Air Force Base (AFB) near Oscoda, Michigan. The plume was discovered by ground penetrating radar (GPR) profiling while extending a long line from FT-02 to establish background variability around that plume. Further GPR surveys were conducted by students of a Western Michigan University geophysics field course to outline the proximal part of the plume. The GPR survey was supplemented by an electromagnetic induction (EM) survey which showed a group of four cables crossing the area. Finally, a magnetometer survey was conducted to search for any buried steel objects which might have been missed by the EM survey. The results of the three geophysical surveys were then used by students of a University of Michigan field course to guide subsurface soil and fluid sampling, which verified the presence of residual LNAPL product and ground water with conductivities 2.5 to 3.3 times above background. The plume source is in the vicinity of a vaulted underground storage tank (UST) formerly used for the collection of waste solvents and fuels for subsequent use in the fire training exercises at FT-02.

Bermejo, J.L.; Sauck, W.A.; Atekwana, E.A.

1997-12-31

363

Effects of hydrodynamic dispersion on plume lengths for instantaneous bimolecular reactions  

NASA Astrophysics Data System (ADS)

In this article a new two-dimensional analytical model is presented, which explores the effects of longitudinal ( ?L) and transverse ( ?T) dispersivity on the transient and steady state length of a plume undergoing an instantaneous bimolecular reaction. A solute B is injected into a steady, uniform flow field in a homogeneous porous medium initially filled with a solute A. Mixing of the solutes occurs only through longitudinal and transversal dispersion and reaction between the solutes is assumed to occur where both solutes are simultaneously present. Explicit steady state solutions (in the limit t??) are presented, which describe the distributions of reactants and products in x- y space in the form of the modified Bessel function of zero order and second kind. When ?T ? ?L ? 10 ?T, i.e., limits typically used in practical engineering scenarios, the steady state length of a contaminant plume is obtained as a simple algebraic expression including ?T; the influence of ?L upon plume length being negligible. This phenomenon has been observed experimentally and in numerical simulations. The analysis provided in this paper proves that this behavior follows directly from the governing equations. In addition, the effects of hydrodynamic dispersion on the transient plume development are investigated. The assumption that ?L is only important for the transient development of the plume is verified through the use of a numerical solution.

Ham, Philip A. S.; Schotting, Ruud J.; Prommer, Henning; Davis, Greg B.

2004-08-01

364

Linear Spectral Analysis of Plume Emissions Using an Optical Matrix Processor  

NASA Technical Reports Server (NTRS)

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

Gary, C. K.

1992-01-01

365

Dynamics and Deposits of Coignimbrite Plumes  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

366

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

USGS Publications Warehouse

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

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

2014-01-01

367

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

PubMed

The changing contaminant pattern with travelled distance was investigated in the anaerobic groundwater plume downstream from an extended zone containing residual NAPL at a former gas manufacturing plant. With increasing distance, O- and N-heterocyclic aromatic compounds are enriched in the plume relative to the usually assessed coal tar constituents (poly- and monocyclic aromatic compounds). In a first approximation, the overall concentration decrease of the investigated compounds follows a first order overall decay. The half life distance in the plume downgradient from the source varied between 20 m for benzene and up to 167-303 m for alkyl-naphthalenes. Acenaphthene is degraded only within about 50 m downstream from the source area, then its concentration remains constant (ca. 180 microg/l) and far above the legal limit. Dimethyl-benzofurans were the most recalcitrant among all compounds which could be quantified with the analytical method available. The overall groundwater contamination in the plume is seriously underestimated if only BTEX and 16-EPA-PAHs are monitored. PMID:11820480

Zamfirescu, D; Grathwohl, P

2001-12-15

368

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

NASA Astrophysics Data System (ADS)

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

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

1988-09-01

369

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

NASA Astrophysics Data System (ADS)

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

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

2005-05-01

370

Radiation from advanced solid rocket motor plumes  

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

371

Microbiology, Redox and Contaminat Fate in the Grindsted Landfill Leachate Plume - A Summary of 25 Years of work  

Microsoft Academic Search

The contamination by leachate of the upper aquifer at the Grindsted Landfill (Denmark) stretches about 300 m downgradient from the landfill. The plume has been described with respect to water chemistry, sediment chemistry, pollutant distribution, microbial counts, PLFA and redox rates determined by unamended bioassays. This presentation summaries the findings and discusses unanswered questions. The landfill was active from 1930

T. H. Christensen

2001-01-01

372

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

373

Digital filtering of plume emission spectra  

NASA Technical Reports Server (NTRS)

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

Madzsar, George C.

1990-01-01

374

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

375

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

USGS Publications Warehouse

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

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

2005-01-01

376

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

NASA Technical Reports Server (NTRS)

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

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

1977-01-01

377

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

SciTech Connect

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

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

2011-02-01

378

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

379

Laser plume temperature measurements in various gases  

SciTech Connect

Nd-YAG laser plume temperatures of 3000--5400K were measured on 304 stainless steel and 1100 Al in various gases using emission spectroscopy. Temperatures were higher in the reactive gases air, 02, and SF6, compared to inert gases. Ionic spectra were not observed, indicating that the plume primarily consists of hot vapors and does not contain a plasma, in contrast to CO/sub 2/ laser processing in which plasmas have been observed. The plume temperature remained constant with changes in laser power and with time during the duration of the laser pulse. Light emissions from the plume and from the cooling weld pool after the laser pulse was off were measured and correlated with melt depth. 7 refs.

Lewis, G.K.; Cremers, D.A.; Dixon, R.D.

1988-01-01

380

Mixing and Transport in Coastal River Plumes  

NASA Astrophysics Data System (ADS)

River plumes are generated by the flow of buoyant river water into the coastal ocean, where they significantly influence water properties and circulation. They comprise dynamically distinct regions spanning a large range of spatial and temporal scales, each contributing to the dilution and transport of freshwater as it is carried away from the source. River plume structure varies greatly among different plume systems, depending on the forcing and geometry of each system. Individual systems may also exhibit markedly different characteristics under varied forcing conditions. Research over the past decade, including a series of major observational efforts, has significantly improved our understanding of the dynamics and mixing processes in these regions. Although these studies have clarified many individual processes, a holistic description of the interaction and relative importance of different mixing and transport processes in river plumes has not yet been realized.

Horner-Devine, Alexander R.; Hetland, Robert D.; MacDonald, Daniel G.

2015-01-01

381

Characterization of ozone plumes in eastern Germany  

NASA Astrophysics Data System (ADS)

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

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

382

Preliminary plume characteristics of an arcjet thruster  

NASA Technical Reports Server (NTRS)

An experimental program initiated to characterize the near field of an arcjet plume is described. The complete emission spectrum from 3200 to 7200 A at the nozzle exit plane detected the electronically excited species N2, N2(+), NH, and H, indicating excitation, dissociation, ionization, and recombination in the nozzle. Axial intensity profiles indicated an exponential decay in excited state population for H(alpha), H(beta), and NH. The rate of axial decay indicated lower velocities for NH than H in the plume and population of the third excited energy state of hydrogen from the decay of higher energy levels. Rotational temperatures ranged from 750 K for N2 to 2500 K for NH. Based on these results, the arcjet plume is found to be a highly nonequilibrium plasma. Anode electrical configuration is found to have a large effect on the spectral intensities measured in the plume.

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

1990-01-01

383

Ozone photochemistry in boreal biomass burning plumes  

NASA Astrophysics Data System (ADS)

We present an analysis of ozone (O3) photochemistry observed by aircraft measurements of boreal biomass burning plumes over eastern Canada in the summer of 2011. Measurements of O3 and a number of key chemical species associated with O3 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. The location and timing of the aircraft measurements put BORTAS into a unique position to sample biomass burning plumes from the same source region in Northwestern Ontario with a range of ages. We found that O3 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 O3 production increased with plume age. We used NMHC ratios to estimate photochemical ages of the observed biomass burning plumes between 0 and 10 days. The BORTAS measurements provided a wide dynamic range of O3 production in the sampled biomass burning plumes with ?O3/?CO enhancement ratios increasing 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. We found that the main contributing factor to the variability in the ?O3/?CO enhancement ratio was ?CO in plumes with photochemical ages less than 4 days, and that was a transition to ?O3 becoming the main contributing factor in plumes with ages greater than 4 days. In comparing O3 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 efficiency (OPE) of 7.7 ± 3.5 ppbv ppbv-1 relative to ?AN and 1.6 ± 0.9 ppbv ppbv-1 relative to NOz. In plumes with ages greater than 4 days, OPE increased to 472 ± 28 ppbv ppbv-1 relative to ?AN and 155 ± 5 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 O3 production in younger plumes was inhibited by high aerosol loading and greater production of ?AN relative to O3. The BORTAS measurements of O3 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.

2013-08-01

384

Propagation of an atmospheric pressure plasma plume  

SciTech Connect

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

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

2009-02-15

385

Propagation of an atmospheric pressure plasma plume  

NASA Astrophysics Data System (ADS)

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

Lu, X.; Xiong, Q.; Xiong, Z.; Hu, J.; Zhou, F.; Gong, W.; Xian, Y.; Zou, C.; Tang, Z.; Jiang, Z.; Pan, Y.

2009-02-01

386

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 transpor