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

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

2

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

SciTech Connect

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

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

1995-08-01

3

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

4

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

5

Delineating landfill leachate discharge to an arsenic contaminated waterway.  

PubMed

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

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

2011-11-01

6

Effect of Data Transformations on Source Identification and Plume Delineation using Dimension Reduction Techniques  

NASA Astrophysics Data System (ADS)

Multivariate statistical approaches such as the Principal Component Analysis (PCA), Factor analysis and clustering algorithms are routinely employed for reducing the dimensionality of data and identifying chemical signatures and potential groupings for multi-species contaminant plumes. Although there are no general restrictions or specific guidelines for application of such approaches, it has been suggested (Aitchison, 1983) that dimensionality reduction techniques based on correlation structure of the analytical data (scaled but not transformed) may not be applicable to compositional data or data subject to equality constraint such as geochemical data. No restrictions have been identified for using such techniques with organic data such as chlorinated hydrocarbons. We examine real world and synthetic datasets that contain a combination of organic and inorganic data and test the impact of different data transformations on the results of PCA and other techniques. We are specifically interested in identifying clusters in the data for delineation of contaminant-specific plumes. We provide comparison with results obtained using traditional methods and evaluate against the known hydrogeological conditions.

Suribhatla, R. M.; Culkin, S. L.; Taraszki, M.

2013-12-01

7

RAPID REMOVAL OF A GROUNDWATER CONTAMINANT PLUME.  

USGS Publications Warehouse

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

Lefkoff, L. Jeff; Gorelick, Steven, M.

1985-01-01

8

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

9

Mapping organic contaminant plumes in groundwater using spontaneous potentials  

NASA Astrophysics Data System (ADS)

Increased water demands have raised awareness of its importance. One of the challenges facing water resource management is dealing with contaminated groundwater; delineating, characterizing and remediating it. In the last decade, spontaneous potentials have been proposed as a method for delineating degrading organic contaminant plumes in groundwater. A hypothesis proposed that the redox potential gradient due to degradation of contaminants generated an electrical potential gradient that could be measured at the ground surface. This research was undertaken to better understand this phenomenon and find under what conditions it occurs. Spontaneous potentials are electrical potentials generated by three sources that act simultaneously: electrokinetic, thermoelectric and electrochemical sources. Over contaminant plumes electrochemical sources are those of interest. Thermoelectric sources are negligible unless in geothermal areas, but we hypothesized that electrokinetic potentials could be impacted by contaminants altering sediment surface properties. We built and calibrated a laboratory apparatus to make measurements that allowed us to calculate streaming current coupling coefficients. We tested sediment from hydrocarbon impacted sites with clean and hydrocarbon polluted groundwater and found a measurable though inconsistent effect. Moreover, numerical modelling was used to demonstrate that the impact of these changes on field measurements was negligible. Spontaneous potential surveys were conducted on two field sites with well characterized degrading hydrocarbon plumes in groundwater. We did not find a correlation between redox conditions and spontaneous potential, even after the electrical measurements were corrected for anthropogenic noise. In order to determine why the expected signal was not seen, we undertook numerical modelling based on coupled fluxes using two hypothesized types of current: redox and diffusion currents. The only scenarios that produced spontaneous potential anomalies at the ground surface were those using the redox hypothesis with a relatively resistive transition zone and strong Eh gradients. These conditions are paradoxical because they imply low and high reaction rates respectively. Surface spontaneous potential anomalies do not occur on all sites with degrading contaminant plumes in groundwater. The models currently available cannot explain why SP and redox potentials are correlated on certain sites and further research would be necessary to explain this phenomenon.

Forte, Sarah

10

Imaging industrial contaminant plumes with resistivity techniques  

NASA Astrophysics Data System (ADS)

A systematic geophysical procedure has been developed and applied to image groundwater contamination caused by industrial activities in Bahia, Brazil. The procedure combines the use of conventional Schlumberger sounding with a regular scheme of sampling the resistivity stratification in depth. This is achieved by traversing an area with multiple profiles measured at selected electrode spacing. By multiple profiles we mean closely spaced partial soundings made using only six electrode spacings. Partial and complete soundings are correlated and inverted assuming horizontally stratified models within the limits covered by each electrode array. Pseudo-resistivity sections constructed from these data are inverted and adjusted using a two-dimensional finite difference algorithm. Electrical and lithological well logs are used to constrain this interpretation. The procedure was successfully applied to investigate the groundwater conditions and to outline contaminant plumes within industrial areas of the Camaçari Petrochemical Center, Recôncavo basin, Bahia. The study includes cases of electrically conductive plumes generated by infiltration of inorganic aqueous effluents and a resistive plume containing hydrocarbon contaminants.

de Lima, Olivar A. L.; Sato, Hédison K.; Porsani, Milton J.

1995-12-01

11

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

12

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

Microsoft Academic Search

Currently, no accurate models or recent data exist for modeling contamination from spacecraft thrusters to meet the stringent requirements of the International Space Station (ISS). Few flight measurements of contaminant deposition from spacecraft thrusters have been made, and no measurements have been made for angles away from the plume centerline. The Plume Impingement Contamination-II (PIC-II) experiment is planned to provide

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

2002-01-01

13

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

14

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

15

U. S. Air Force approach to plume contamination  

NASA Astrophysics Data System (ADS)

Exhaust products from rocket engine firings can produce undesirable effects on sensitive satellite surfaces, such as optical systems, solar cells, and thermal control surfaces. The Air Force has an objective of minimizing the effect of rocket plume contamination on space-craft mission effectiveness. Plume contamination can result from solid rocket motors, liquid propellant engines, and electric thrusters. To solve the plume contamination problem, the Air Force Rocket Propulsion Laboratory (AFRPL) has developed a plume contamination computer model which predicts the production, transport, and deposition of rocket exhaust products. In addition, an experimental data base is being obtained through ground-based vacuum chamber experiments and in-flight measurements with which to compare the analytical results. Finally, the experimental data is being used to verify and improve the analytical model. The plume contamination model, known as CONTAM, has been used to make contamination predictions for various engines. The experimental programs have yielded quantitative data, such as species concentrations and temperatures, in all regions of the plume. The result of the modelling and experimental programs will ultimately be computer models which can be used by the satellite designer to analyze and to minimize the effect plume contamination will have on a particular spacecraft system.

Furstenau, Ronald P.; McCay, T. Dwayne; Mann, David M.

1980-08-01

16

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

NASA Astrophysics Data System (ADS)

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

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

2000-06-01

17

Hydrogeophysical investigations of the former S-3 ponds contaminant plumes  

SciTech Connect

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

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

2013-01-01

18

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

PubMed

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. PMID:22784635

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

2012-08-01

19

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

20

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

21

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

NASA Astrophysics Data System (ADS)

Currently, no accurate models or recent data exist for modeling contamination from spacecraft thrusters to meet the stringent requirements of the International Space Station (ISS). Few flight measurements of contaminant deposition from spacecraft thrusters have been made, and no measurements have been made for angles away from the plume centerline. The Plume Impingement Contamination-II (PIC-II)1 experiment is planned to provide such measurements using quartz crystal microbalances placed into the plume of a Shuttle Orbiter RCS thruster. To this end, the Johns Hopkins University Applied Physics Laboratory (APL) has supported NASA in the development of the PIC-II experiment Flight Electronics Unit known as the Remote Arm TQCM System (RATS), which will measure the contamination in the Shuttle Obiter RCS thruster. The development was based on an ongoing effort between the APL and QCM Research to develop an inexpensive, miniature TQCM controller based on a legacy of QCM controllers developed at the APL. PIC-II will provide substantial improvements over previous systems, including higher resolution, greater flexibility, intensive housekeeping, and in-situ operational control. Details of the experiment hardware and measurement technique are given. The importance of the experiment to the ISS and the general plume contamination community is discussed.

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

2002-09-01

22

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

23

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

24

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 ...

25

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

26

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...

27

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

28

Shuttle PRCS plume contamination analysis for Astro-2 mission  

NASA Technical Reports Server (NTRS)

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

Wang, Francis C.; Greene, Cindy

1993-01-01

29

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

SciTech Connect

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

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

1998-09-01

30

Resolving superimposed ground-water contaminant plumes characterized by chromium, nitrate, uranium, and technetium--99  

SciTech Connect

Leakage from a liquid waste storage and solar evaporation basin at the Hanford Site in southeastern Washington State has resulted in a ground-water contaminant plume characterized by nitrate, hexavalent chromium, uranium, and technetium-99. The plume is superimposed on a larger, pre-existing plume extending from upgradient sites and having the same suite of contaminants. However, the relative abundance of contaminant species is quite different for each plume source. Thus, characteristic concentration ratios, rather than concentrations of individual species, are used as geochemical tracers, with emphasis on graphical analysis. Accordingly, it has been possible to resolve the boundaries of the smaller plume and to estimate the contribution of each plume to the observed contamination downgradient from the storage basin. 11 refs., 7 figs.

Hall, S.H.

1990-02-01

31

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 ...

32

Consolidation of the landfill stabilization and contaminant plumes focus areas  

SciTech Connect

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

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

1996-12-31

33

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

SciTech Connect

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

BENECKE, M.W.

2007-05-29

34

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

35

Source Inversion for Contaminant Plume Dispersion in Urban Environments Using Building-Resolving Simulations  

Microsoft Academic Search

The ability to determine the source of a contaminant plume in urban environments is crucial for emer- gency-response applications. Locating the source and determining its strength based on downwind concen- tration measurements, however, are complicated by the presence of buildings that can divert flow in unexpected directions. High-resolution flow simulations are now possible for predicting plume evolution in complex urban

Fotini Katopodes Chow; Branko Kosovic; Stevens Chan

2008-01-01

36

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

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

37

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

38

Integration of Predicted Atmospheric Contaminant Plumes into ArcView GIS  

Microsoft Academic Search

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

Larry D

2005-01-01

39

Allocating Remedial Costs at Superfund Sites with Commingled Groundwater Contaminant Plumes  

Microsoft Academic Search

Remedial efforts at Superfund sites across the country focus on groundwater contaminant plumes that have been produced by contributions from multiple parties. Allocating cleanup costs between the parties in a fair and equitable manner can be a problem of substantial complexity. Considerable time and money may be spent determining the amount of contamination attributable to each party in order to

Robert A. Marryott; Gabriel P. Sabadell; David P. Ahlfeld; Robert H. Harris; George F. Pinder

2000-01-01

40

A multilayer groundwater sampler for characterizing contaminant plumes. Final report  

SciTech Connect

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

Kaplan, E.; Heiser, J.

1992-12-18

41

A multilayer groundwater sampler for characterizing contaminant plumes  

SciTech Connect

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

Kaplan, E.; Heiser, J.

1992-12-18

42

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

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

43

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

44

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

NASA Astrophysics Data System (ADS)

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

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

2006-12-01

45

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

46

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

E-print Network

USE OF SUPERPOSITION AND THE EXTENDED PULSE MODEL TO EVALUATE THE CONTAMINANT TRANSPORT PARAMETERS OF VARIABLY SOURCE-LOADED PLUMES A Thesis by DONALD WAYNE HANKINS Submitted to the Graduate College of Texas A&M University in partial... fulfillment of the requirements for the degree of MASTER OF SCIENCE December 1988 Major Subject: Geology USE OF SUPERPOSITION AND THE EXTENDED PULSE MODEL TO EVALUATE THE CONTAMINANT TRANSPORT PARAMETERS OF VARIABLY SOURCE-LOADED PLUMES A Thesis...

Hankins, Donald Wayne

2012-06-07

47

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

48

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

NASA Technical Reports Server (NTRS)

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

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

1972-01-01

49

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

NASA Technical Reports Server (NTRS)

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

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

1971-01-01

50

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...

51

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

52

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

USGS Publications Warehouse

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

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

1986-01-01

53

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...

54

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

NASA Astrophysics Data System (ADS)

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

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

2005-12-01

55

Geoelectrical Methods Applied to Contaminant Plumes. From Laboratory to Field Investigations  

NASA Astrophysics Data System (ADS)

At present, the self-potential method, a relatively cheap field method, is rarely used in environmental investigations due to the lack of reliable interpretation schemes and poor knowledge of the signal-to-noise ratio. The self-potential signals measured at the ground surface with a new generation of non-polarisable electrodes represent the ground signature of in situ polarization mechanisms. Two main driving mechanisms have been evidenced. The first is the electrokinetic response associated with ground water flow. The second contribution is associated with redox conditions in the ground. In this talk, we will present a set of new data for these two mechanisms. These data include core measurements, measurements in plexiglas tanks filled with porous sands, and finally a field experiment. The field investigation is related to the detection of a contaminant plume through a combination of electrical resistivity tomographies and self-potential investigations. We show how laboratory experiments are helpful to determine redox conditions in the contaminant plume and we will discuss the principle of electro-redox geobatteries including the role of biofilm of bacteria.

Revil, A.; Naudet, V.; Suski, B.; Rizzo, E.; Bezis, S.

2003-12-01

56

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

57

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

58

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

59

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...

60

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

Microsoft Academic Search

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

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

2011-01-01

61

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

E-print Network

methodology based on Bayesian inference cou- pled with stochastic sampling. Bayesian methods re- formulateJ4.4 SOURCE INVERSION FOR CONTAMINANT PLUME DISPERSION IN URBAN ENVIRONMENTS USING BUILDING an inverse problem becomes quite chal- lening. That is, given measurements of concentration at sensors

Chow, Fotini Katopodes

62

Rapid delineation of subsurface petroleum contamination using the site characterization and analysis penetrometer system  

Microsoft Academic Search

The Site Characterization and Analysis Penetrometer System (SCAPS) was used to investigate subsurface petroleum contamination\\u000a at Aberdeen Proving Ground, Maryland. The SCAPS is a rapid site-screening tool developed by the Tri-Services (U.S. Army, Navy,\\u000a and Air Force) to reduce the cost of installation restoration activities. The system, consisting of a geophysical cone penetrometer\\u000a fitted with a laser-induced fluorescence petroleum sensor,

W. M. Davis; E. R. Cespedes; L. T. Lee; J. F. Powell; R. A. Goodson

1997-01-01

63

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

64

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

PubMed

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

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

2005-11-01

65

In Situ Remediation of 129I in a Multiple Contaminant Plume (Invited)  

NASA Astrophysics Data System (ADS)

In situ treatment of a multi-contaminant plume is difficult because of the different geochemical behavior of contaminants. Treatment of 129I in contaminated groundwater associated with the F-Area Seepage Basins on the Savannah River Site illustrates the dilemma. Co-contaminants include uranium and 90Sr which are being treated in situ by elevating groundwater pH. Yet, this does not treat 129I. Injection of silver chloride (AgCl) particles to immobilize 129I is compatible with the pH adjustment and has been successfully tested at bench and field scales. AgCl reacts with iodide to form insoluble silver iodide (logKsp=-16.1). In addition, AgCl has a low solubility, is stable in subsurface environments, and is unlikely to become occluded by microbial growth. Iodide is one of the few constituents in groundwater that reacts with AgCl and at natural iodine (127I) concentrations, on the order of 2-4 ?g/L, interference with the sequestration of 129I is minimal. An initial phase of laboratory studies demonstrated that AgCl particles were injectable into sediment filled columns simulating the contaminated aquifer and were capable of removing iodide from solution. A mass of AgCl particles approximately 0.05% the mass of sediment was injected into the column. This was followed by injection of a solution containing 7.5 mg/L iodide. Column effluent measurements indicated that the iodide concentration was reduced by over 90% for 51 pore volumes - the point at which the experiment was terminated. Analysis of the column sediment by x-ray fluorescence indicated that AgCl particles had penetrated a minimum of 12 cm into the column. Subsequent experiments showed that AgCl is stable over a wide range of pH values, exhibiting an increase in solubility at pH=10 with solubility increasing as pH increases beyond 10. A field test is ongoing at the F-Area Seepage Basins site in which a AgCl particle-water mixture was injected into three wells spaced 15 meters apart and screened in the 129I containing plume. The maximum concentration of AgCl in the mixture was 50 mg/L and approximately 1.2x106 liters were injected. The injection occurred at the end of a barrier wall that is part of a funnel-and-gate system. Four existing wells at the end of the wall were used to monitor the field experiment. Samples from a monitoring well 8 meters downgradient of the central injector have continued to show a 50% reduction in 129I concentration over the last 10 months. The rapid rebound of tritium in this well to pre-test concentrations indicates the reduction in 129I is the result of reaction with the AgCl particles. The magnitude of the reduction in 129I concentration is likely the result of heterogeneous distribution of AgCl particles across the treatment zone. Only small reductions in 129I concentrations in samples from the other monitoring wells have been observed. It is believed that these wells are in the path of groundwater moving around the edge of the barrier wall and are not regularly sampling groundwater that has passed through the treatment zone.

Denham, M.; Nichols, R.; Whiteside, M.; Bickmore, C.; Millings, M.; Blount, G.; Thibault, J.

2010-12-01

66

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

NASA Astrophysics Data System (ADS)

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

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

2006-12-01

67

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

68

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

National Technical Information Service (NTIS)

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

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

1997-01-01

69

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

SciTech Connect

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

Sorenson, Kent S. Jr.

2003-06-01

70

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

71

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

72

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

73

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

74

Flushing of organic contaminants from a groundwater plume at the Rocky Mountain Arsenal. Volume 2: Appendices  

Microsoft Academic Search

During the summer of 1988, UCLA conducted a field experiment on flushing of organic contaminants from a contaminated aquifer in the western tier of RMA. The objectives of the study were to: (1) Estimate the hydraulic conductivity of the aquifer; (2) Estimate the degree to which TRCLE and 111TCE are retarded in their mobility due to sorption by the aquifer

D. M. McKay; K. W. Thorbjarnarson

1990-01-01

75

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

76

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

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

77

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

PubMed Central

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

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

2013-01-01

78

A comparison of shuttle vernier engine plume contamination with CONTAM 3.4 code predictions  

NASA Technical Reports Server (NTRS)

In 1985, using the CONTAM 3.2 code, it was predicted that the shuttle Primary Reaction Control System (PRCS) and Vernier Reaction Control System (VRCS) engines could be potential contamination sources to sensitive surfaces located within the shuttle payload bay. Spaceflight test data on these engines is quite limited. Shuttle mission STS-32, the Long Duration Exposure Facility retrieval mission, was instrumented with an experiment that provided the design engineer with evidence that contaminant species from the VRCS engines can enter the payload bay. More recently, the most recent version of the analysis code, CONTAM 3.4, has re-examined the contamination potential of these engines.

Maag, Carl R.; Jones, Thomas M.; Rao, Shankar M.; Linder, W. Kelly

1992-01-01

79

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

80

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 0.001Bq/L (1Bq/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 >1.7Bq/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

81

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

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

82

Mapping of contaminant plumes with geoelectrical methods. A case study in urban context  

NASA Astrophysics Data System (ADS)

During the past two decades, the diagnosis and monitoring of polluted sites have become more important. Urban sites are particularly difficult to study, because they are contaminated with various pollutants, and there is a large physical and chemical heterogeneity. The heterogeneity comes from the landfilling of various solid wastes and remolded soil (endogenous or exogenous) from which they were constituted over time. Traditional techniques such as wells monitoring, are often insufficient to evaluate the extension of soil contamination. This is why we proposed a geoelectrical methodology from the fastest to the most information rich technique, showing all carry out and acquisition times: electromagnetic low frequency conductivity mapping, electrical resistivity profiles, chargeability profiles and spectral induced polarization (SIP) soundings. This strategy has been successfully applied to an urban site located in the Paris Basin (France). A conductivity map in relation with geochemical and lithological informations should provide us information to implement electrical resistivity and chargeability profiles. The latter allowed us to differentiate 3 main anomaly zones that have been determined. As interpretation of chargeability profiles is difficult, because it integrates polarization mechanisms with different relaxation times, we add spectral induced polarization soundings that provide us information concerning the contaminant nature. We determined the extension of an organic phase, and of 2 highly mineralized zones that could be linked to biodegraded and/or with pyrite areas. That theory is consistent with groundwater analysis and SIP data. The conclusion is that the suggested methodology is well suited to the study of urban contaminated sites including several different pollutants.

Vaudelet, P.; Schmutz, M.; Pessel, M.; Franceschi, M.; Guérin, R.; Atteia, O.; Blondel, A.; Ngomseu, C.; Galaup, S.; Rejiba, F.; Bégassat, P.

2011-12-01

83

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

SciTech Connect

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

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

2005-06-01

84

Plume Busters  

NSDL National Science Digital Library

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

Macfarlane, Allen

85

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

86

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

87

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

88

Source Inversion for contaminant plume dispersion in urban environments using building-resolving simulations  

SciTech Connect

Flow in urban environments is complicated by the presence of buildings, which divert the flow into often unexpected directions. Contaminants released at ground level are easily lofted above tall ({approx} 100 m) buildings and channeled through urban canyons that are perpendicular to the wind direction (see e.g., IOP 9 in Chan, 2005). The path of wind and scalars in urban environments is difficult to predict even with building-resolving computational fluid dynamics codes, due to the uncertainty in the synoptic wind and boundary conditions and other errors in the models. Given the difficulties due to the complexity of urban flows, solving an inverse problem becomes quite challenging. That is, given measurements of concentration at sensors scattered throughout a city, is it possible to detect the source of the contaminant? The ability to locate a source and determine its characteristics in a complex environment is necessary for emergency response for accidental or intentional releases of contaminants in densely-populated urban areas. The goal of this work is to demonstrate a robust statistical inversion procedure that performs well even under the complex flow conditions and uncertainty present in urban environments. Much work has previously focused on direct inversion procedures, where an inverse solution is obtained using an adjoint advection-diffusion equation. The exact direct inversion approaches are strictly limited to processes governed by linear equations. In addition, they assume the system is steady-state and that the equations are linear (Enting, 2002). In addition to adjoint models, optimization techniques are also employed to obtain solutions to inverse problems. These techniques often give only a single best answer, or assume a Gaussian distribution to account for uncertainties. General dispersion related inverse problems, however, often include non-linear processes (e.g., dispersion of chemically reacting substances) or are characterized by non-Gaussian probability distributions (Bennett, 2002). Traditional methods also have particular weaknesses for sparse, poorly constrained data problems, as well as in the case of high-volume, potentially over-constrained and diverse data streams. We have developed a more general and powerful inverse methodology based on Bayesian inference coupled with stochastic sampling. Bayesian methods reformulate the inverse problem into a solution based on efficient sampling of an ensemble of predictive simulations, guided by statistical comparisons with observed data. Predicted values from simulations are used to estimate the likelihoods of available measurements; these likelihoods in turn are used to improve the estimates of the unknown input parameters. Bayesian methods impose no restrictions on the types of models or data that can be used. Thus, highly non-linear systems and disparate types of concentration,meteorological and other data can be simultaneously incorporated into an analysis. In this work we have implemented stochastic models based on Markov Chain Monte Carlo sampling for use with a high-resolution building-resolving computational fluid dynamics code, FEM3MP. The inversion procedure is first applied to flow around an isolated building (a cube) and then to flow in Oklahoma City (OKC) using data collected during the Joint URBAN 2003 field experiment (Allwine, 2004). While we consider steady-state flows in this first demonstration, the approach used is entirely general and is also capable of dealing with unsteady, nonlinear governing equations.

Chow, F K; Kosovic, B; Chan, S T

2005-11-04

89

Plume Busters  

NSDL National Science Digital Library

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

Macfarlane, P.; Bohling, Geoffrey

90

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

91

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

NASA Astrophysics Data System (ADS)

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.

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

2013-05-01

92

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

93

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

94

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

95

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

96

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

97

Effect of bipropellant plume exhaust effluents on spaceborne optical instruments  

Microsoft Academic Search

Analytical tools together with a good data base are necessary to predict the transport of plume contaminants and their effects on spacecraft surfaces. The present paper describes an assessment of bipropellant thrusters, the production and transport of plume contaminants from these thrusters, and the use of the JPL contamination analysis program to assess the effects of plume contamination on the

C. R. Maag; J. A. Jeffery; J. M. Millard

1980-01-01

98

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

99

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

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

100

Evaluation of Visible Plumes.  

ERIC Educational Resources Information Center

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

Brennan, Thomas

101

Assessment of diesel contamination in groundwater using electromagnetic induction geophysical techniques.  

PubMed

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. PMID:18393065

Jin, Song; Fallgren, Paul; Cooper, Jeffrey; Morris, Jeffrey; Urynowicz, Michael

2008-05-01

102

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

103

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...

104

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

105

Effect of bipropellant plume exhaust effluents on spaceborne optical instruments  

NASA Astrophysics Data System (ADS)

Analytical tools together with a good data base are necessary to predict the transport of plume contaminants and their effects on spacecraft surfaces. The present paper describes an assessment of bipropellant thrusters, the production and transport of plume contaminants from these thrusters, and the use of the JPL contamination analysis program to assess the effects of plume contamination on the Galileo spacecraft. It is shown that, in the case of the Galileo mission, contamination from the liquid engines has been effectively reduced to nothing by the use of predictive tools. Plume shields together with precise scan platform stowage have been designed to protect the optical instruments.

Maag, C. R.; Jeffery, J. A.; Millard, J. M.

1980-01-01

106

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

107

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

108

Integrated characterisation of aquifer heterogeneity and landfill leachate plume migration  

NASA Astrophysics Data System (ADS)

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

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

2009-05-01

109

NEW LAGRANGIAN APPROACH FOR WET PLUME MODELLING , F Tognet1  

E-print Network

: Microphysics, lagrangian, dispersion, modelling, spray, microorganisms, legionella, wet plume, INTRODUCTION. In the specific case of Legionella, accidental spread in the atmosphere due to contaminated cooling towers (CT

Paris-Sud XI, Université de

110

Finiteness of steady state plumes  

NASA Astrophysics Data System (ADS)

The finite maximum length of a steady state contaminant plume is determined by developing and employing a new analytical solution which overcomes two drawbacks associated with existing approaches. First, we account for a sharp front caused by the complete consumption of the pollutant ("electron donor") and some electron acceptor in an instantaneous binary reaction occurring at the front. This approach is not based on purely conservative or first-order degradation models which lead to theoretically infinite plumes and, in addition, depend on a concentration threshold. Second, a vertical aquifer cross section with finite thickness is selected as a model in order to better represent the supply of electron acceptors mostly entering the aquifer from the top. This type of setting allows investigation of the impact of aquifer thickness on plume length. An implicit representation of the donor-acceptor front in a finite vertical domain previously required numerical solutions of the underlying advection-dispersion-reaction equation; we provide for the first time an analytical solution of this two-dimensional transport problem. The length of the plume is found to be given by the point of intersection of the donor-acceptor front and the aquifer bottom. Furthermore, a rather simple and highly accurate approximation is derived to compute the steady state plume length. A comprehensive sensitivity analysis reveals that results are most strongly influenced by aquifer thickness, followed by vertical transverse dispersivity and, to a somewhat lesser extent, by chemical reaction parameters. Longitudinal dispersivity has practically no effect on plume length, and furthermore, there is zero impact of linear velocity. With regard to groundwater risk assessment at the field scale it is also important to note that the present approach is meant to provide an upper bound on the actual plume length. Further research activities may be directed to refine the transport model by considering, for instance, degradation inside the plume and the limited vertical extent of the contaminant source.

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

2005-12-01

111

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

112

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

SciTech Connect

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

Smoot, J.L.; Sagar, B.

1990-01-01

113

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

114

Plume Delineation of a Pulp and Paper Mill Outfall  

E-print Network

tracer dye was pumped into the pulp mill effluent discharge at a continuous rate for 29 hours. An in situ.3. Normalizing illumination differences using ratios 3.4. Calibration of airborne imagery in effluent concentration units 4.0 Discussion 4.1 Image 1 (11 :58 PDT) 4.2 Image 2 (12:22 PDT) 4.3 Image 3 (14:48 PDT) 4

115

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

116

Groundwater Contamination  

NSDL National Science Digital Library

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

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

117

Candida albicans strain delineation.  

PubMed Central

Candida albicans is a major opportunistic pathogen causing a wide spectrum of disease in human beings. Methods for strain delineation of this species to assess or predict virulence or to conduct epidemiologic or pathogenetic investigations have been developed. Although factors associated with virulence have been identified, there is no rapid system to quantitate them in a clinical laboratory. Therefore, many typing methods are based on variable phenotypic characteristics within this species including morphotyping, serotyping, antibiogram, resistogram typing, biotyping, biotyping based on commercial carbon assimilation patterns, enzyme profiles, sensitivity to yeast killer toxins, and typing based on protein variability. Phenotypically defined strains generally do not correlate with the pathogenic potential of a strain with the exception of morphotyping. However, these methods can be useful in epidemiologic investigations; for example, they have revealed that most individuals harbor one strain and that infections are frequently due to an endogenous strain. Problems with these methods usually relate to their discriminatory power. When this is maximized, reproducibility (especially between laboratories) suffers. Recently, methods based on differences in DNA structure (genotyping) for strain delineation have been developed, including electrophoretic karyotyping and restriction enzyme fragment length polymorphisms. The development of a computer-assisted data bank and analysis for these genotypic strain delineators will open investigations into the pathogenesis of this infection and permit epidemiologic studies previously not possible with this important human pathogen. PMID:1977511

Merz, W G

1990-01-01

118

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

119

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

120

Anatomy of a Pathological Mantle Plume  

NASA Astrophysics Data System (ADS)

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

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

2008-12-01

121

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

122

Application of dig-face monitoring during excavation of a radioactive plume  

SciTech Connect

Dig-face characterization is a concept for improving the safety and efficiency of hazardous waste retrieval. A dig-face characterization system consists of onsite hardware for collecting detailed information on the changing chemical, radiological, and physical conditions in the subsurface during the entire course of a hazardous site excavation. The dig-face characterization concept originated at the Idaho National Engineering Laboratory and has been under development there since 1992. During August 1995, a prototype dig-face system was taken to Mound Laboratory, Ohio, for a first attempt at monitoring a hazardous excavation. Mound Area 7 was the site of historical disposals of {sup 232}Th, {sup 227}Ac, and assorted debris. The dig-face characterization system was used to monitor a 20-ft x 20-ft x 5-ft-deep excavation aimed at removing {sup 227}Ac contaminated soils. Radiological, geophysical, and topographic sensors were scanned across the excavation dig-face at four successive depths as soil was removed in 1-ft to 2-ft lifts. The geophysical and topographic sensors located metallic debris and mapped the dig-face topography in great detail as the excavation advanced. The radiation sensors produced high-fidelity images showing the location of radioactive contaminants and clearly identified and delineated separate {sup 232}Th and {sup 227}Ac plumes. By combining the radiation data from all four levels, a three-dimensional image of the contamination plumes was developed. The radiation sensor data indicated that only a small portion of the excavated soil volume was contaminated. The spatial information produced by the dig-face system was used to direct the excavation activities into the area containing the {sup 227}Ac and to evaluate options for handling the separate {sup 232}Th plume.

Josten, N.E.; Gehrke, R. [Idaho National Engineering Laboratory, Idaho Falls, ID (United States); Stanley, R.; MacMahan, K. [EG& G Mound Applied Technologies, Miamisburg, OH (United States)

1996-11-01

123

Flushing of organic contaminants from a groundwater plume at the Rocky Mountain Arsenal, Volume 1: Field and laboratory studies. (Draft report)  

Microsoft Academic Search

During the summer of 1986, UCLA conducted a field experiment on flushing organic contaminents from a contaminated aquifer in the western tier of RMA. The objectives of the study were to: (1) Estimate the hydraulic conductivity of the aquifer; (2) Estimate the degree to which TRCLE and 111TCE are retarded in their mobility due to sorption by the aquifer media;

D. M. Mackay; K. W. Thorbjarnarson

1990-01-01

124

Contamination  

NASA Technical Reports Server (NTRS)

Contamination of spacecraft in the aerospace environment is examined. The optical systems, thermal control systems and solar power systems were deemed to be most vulnerable to particle damage. It was decided that all orbits should be considered. Specific issues concern whether there are changes in transmittance of optics and the radiative properties of protective coatings.

Maag, Carl R.

1989-01-01

125

Mississippi Plumes  

NSDL National Science Digital Library

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

Center, Nasa G.; Day, Earth S.

126

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

127

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

Microsoft Academic Search

Trichloroethene (TCE), a common groundwater contaminant, can be degraded under certain conditions by microorganisms that occur naturally in the subsurface. TCE can be degraded under anaerobic conditions to less chlorinated compounds and ultimately into the non-chlorinated, non-hazardous end product, ethene, via anaerobic reductive dechlorination (ARD). ARD is widely recognized as a TCE degradation mechanism, and occurs in active groundwater remediation

Robert C. Starr

2005-01-01

128

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

129

Anaerobic Methane Oxidation in a Landfill-Leachate Plume  

E-print Network

Anaerobic Methane Oxidation in a Landfill-Leachate Plume E T H A N L . G R O S S M A N , * , L U I of leachate contamination into underlying aquifers. Landfills are the U.S.'s largest anthropogenic sourceNormanLandfillinOklahomaprovidesanexcellentnatural laboratory for the study of anaerobic methane oxidation in landfill-leachate plumes. Several comprehensive

Grossman, Ethan L.

130

Innovative measures for subsurface chromium remediation: Source zone, concentrated plume, and dilute plume. Environmental research brief  

SciTech Connect

This environmental research brief reports on innovative measures for addressing subsurface chromium contamination. For the source zone, surfactant-enhanced chromium extraction is evaluated for expediting the removal of chromium from the source zone soils, thereby mitigating the continual feeding of the ground-water plume. For the concentrated plume, polyelectrolyte-enhanced ultrafiltration (PEUF) is evaluated as an innovative treatment process with desirable operating characteristics (less sludge production, higher quality final water, etc.), Relative to the dilute plume, the hydrogeological effectiveness of hydraulically passive, chemically reactive barrier systems is evaluated (i.e., in situ reduction of Cr(VI) to Cr(III)).

Sabatini, D.A.; Knox, R.C.; Tucker, E.E.; Puls, R.W.

1997-09-01

131

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

132

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

133

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

NASA Astrophysics Data System (ADS)

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

Deceuster, John; Kaufmann, Olivier

2012-08-01

134

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

PubMed

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

Deceuster, John; Kaufmann, Olivier

2012-08-01

135

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

136

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

137

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

138

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

139

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

140

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

NASA Technical Reports Server (NTRS)

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

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

1973-01-01

141

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)....

142

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

NASA Technical Reports Server (NTRS)

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

1976-01-01

143

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

144

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

145

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

Microsoft Academic Search

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 instaIled within the contaminant plume at the source of the contamination, and at 250 and 2100 m downgradient from the source. Depth profiles of

R. Smith; R HARVEY; D LEBLANC

1991-01-01

146

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

147

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

148

Stochastic analytical modeling of the biodegradation of steady plumes.  

PubMed

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). PMID:24374252

Zarlenga, A; Fiori, A

2014-02-01

149

Delineating the concept of hope.  

PubMed

This description of the concept of hope was developed using interview data from four participant groups: patients undergoing heart transplant, spinal cord-injured patients, breast cancer survivors, and breastfeeding mothers intending to continue nursing while employed. Advanced techniques of concept analysis (using qualitative methods) enabled the delineation of the seven abstract and universal components of hope: a realistic initial assessment of the predicament or threat, the envisioning of alternatives and the setting of goals, a bracing for negative outcomes, a realistic assessment of personal resources and of external conditions and resources, the solicitation of mutually supportive relationships, the continuous evaluation for signs that reinforce the selected goals, and a determination to endure. Comparison of the various manifestations of these components in the four participant groups revealed unique and distinct patterns of hope. These were labeled: hoping for a chance, incremental hope, hoping against hope, and provisional hope. The implications for nursing practice are discussed. PMID:8530115

Morse, J M; Doberneck, B

1995-01-01

150

Colloid Formation and Transport at Waste Plume Fronts  

NASA Astrophysics Data System (ADS)

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

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

2004-12-01

151

Development of Jovian Impactor Plumes  

Microsoft Academic Search

We have simulated the entry of cometary nuclei into Jupiter (Korycansky et al. 2006 ApJ 646. 642-652) and now extend our 3D hydrodynamic models to plume formation and blowout. We investigate the physics that control plume behavior, including why and where plumes \\

Csaba J. Palotai; D. G. Korycansky; J. Harrington; T. Gabriel

2010-01-01

152

Heat sources for mantle plumes  

Microsoft Academic Search

Melting anomalies in the Earth's upper mantle have often been attributed to the presence of mantle plumes that may originate in the lower mantle, possibly from the core-mantle boundary. Globally, mantle plumes exhibit a large range in buoyancy flux that is proportional to their temperature and volume. Plumes with higher buoyancy fluxes should have higher temperatures and experience higher degrees

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

2008-01-01

153

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

154

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

155

Improving operational plume forecasts  

NASA Astrophysics Data System (ADS)

Forecasting how plumes of particles, such as radioactive particles from a nuclear disaster, will be transported and dispersed in the atmosphere is an important but computationally challenging task. During the Fukushima nuclear disaster in Japan, operational plume forecasts were produced each day, but as the emissions continued, previous emissions were not included in the simulations used for forecasts because it became impractical to rerun the simulations each day from the beginning of the accident. Draxler and Rolph examine whether it is possible to improve plume simulation speed and flexibility as conditions and input data change. The authors use a method known as a transfer coefficient matrix approach that allows them to simulate many radionuclides using only a few generic species for the computation. Their simulations work faster by dividing the computation into separate independent segments in such a way that the most computationally time consuming pieces of the calculation need to be done only once. This makes it possible to provide real-time operational plume forecasts by continuously updating the previous simulations as new data become available. They tested their method using data from the Fukushima incident to show that it performed well. (Journal of Geophysical Research-Atmospheres, doi:10.1029/2011JD017205, 2012)

Balcerak, Ernie

2012-04-01

156

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

157

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

158

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

159

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

160

Hotspots: Mantle Thermal Plumes  

NSDL National Science Digital Library

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

161

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...

162

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...

163

THE TREATMENT OF CONTAMINATED WATER AT REMEDIAL WOOD PRESERVING SITES  

EPA Science Inventory

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

164

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

165

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

166

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

SciTech Connect

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

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

1990-01-01

167

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

SciTech Connect

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

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

1990-12-31

168

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

169

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

170

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

171

43 CFR 3922.40 - Tract delineation.  

...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

172

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

PubMed

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

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

2005-10-01

173

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 ...

174

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

175

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

176

Simple models of tropical plumes  

E-print Network

Tropical plumes are upper and mid-level cloud bands at least 2000 km long that cross 15' latitude. The simplest conditions that lead to tropical plume development are sought in a barotropic model simulating winter 200 mb flow. The features sought...

Carrie, Gordon David, d 1960-

2012-06-07

177

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...

178

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

179

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...

180

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

181

Mathematical Modelling to Trace the Leachate Plume of the Municipal Landfill in Groundwater Environment  

Microsoft Academic Search

At outside, the landfill A in Japan contamination has been found. It has been believed that the leachate must leak out from\\u000a the municipal landfill site. Therefore, simulation of the movement of leachate was carried out to understand the behavior\\u000a of the plume at the landfill site. The plume movement was simulated by the three-dimensional solute transport coupled with\\u000a groundwater

Thuong Huyen Dang; Kenji Jinno; E. D. P. Perera

2009-01-01

182

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

183

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

184

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

185

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

186

Delineation of fault zones using imaging radar  

NASA Technical Reports Server (NTRS)

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

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

1986-01-01

187

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

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

188

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

SciTech Connect

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

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

1991-05-14

189

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

190

Plume distortion and apparent attenuation due to concentration averaging in monitoring wells  

SciTech Connect

Mathematical models that simulate common monitoring well sampling demonstrate the distortions that vertical concentration averaging causes during the mapping and modeling of an idealized, three-dimensional contaminant plume emanating from a simple source of constant solute concentration. The apparent extent of the plume, mapped using simulations of a regular grid of screened monitoring wells, ranged from a worst case of 0% of the original plume area for long screens in a low-permeability formation to 90% for short screens in a high-permeability formation. When well design and purging procedure were inconsistent among wells, the mapped plume exhibited spurious directional skewing, bifurcation, zones of low concentration, intermittent sources, or multiple sources. Although the study plume was not retarded, calibrating a transport model to the monitoring well data resulted in retardation factors of up to 23. Apparent retardation or decay was inconsistent from well to well, depending on the saturated screen length, the degree of screen desaturation during purging, and the distance from the source. The study indicates that the quantitative assessment of contaminant distributions and transport processes requires discrete vertical sampling in the common situation where concentrations vary sharply with depth, even in the most ideal hydrogeologic environment. If screened monitoring wells are used, screen lengths and placements should be appropriate to the contamination situation being assessed and inherent biases must be considered. Even so, vertical concentration averaging biases and the resulting inconsistencies can result in highly misleading evaluations of ground-water contamination problems.

Martin-Hayden, J.M. [Univ. of Toledo, OH (United States). Dept. of Geology; Robbins, G.A. [Univ. of Connecticut, Storrs, CT (United States). Dept. of Geology and Geophysics

1997-03-01

191

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.

192

Evaluation of Concrete Median Barrier Delineation Under Poor Visibility Conditions.  

National Technical Information Service (NTIS)

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

L. J. French, K. A. French

2002-01-01

193

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...

194

Lidar sounding of volcanic plumes  

NASA Astrophysics Data System (ADS)

Accurate knowledge of gas composition in volcanic plumes has high scientific and societal value. On the one hand, it gives information on the geophysical processes taking place inside volcanos; on the other hand, it provides alert on possible eruptions. For this reasons, it has been suggested to monitor volcanic plumes by lidar. In particular, one of the aims of the FP7 ERC project BRIDGE is the measurement of CO2 concentration in volcanic gases by differential absorption lidar. This is a very challenging task due to the harsh environment, the narrowness and weakness of the CO2 absorption lines and the difficulty to procure a suitable laser source. This paper, after a review on remote sensing of volcanic plumes, reports on the current progress of the lidar system.

Fiorani, Luca; Aiuppa, Alessandro; Angelini, Federico; Borelli, Rodolfo; Del Franco, Mario; Murra, Daniele; Pistilli, Marco; Puiu, Adriana; Santoro, Simone

2013-10-01

195

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

196

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

197

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

198

Trichloroethene (TCE) Contamination In An Unconfined Sand Aquifer Underlying A Residential Area Of Perth, Western Australia  

Microsoft Academic Search

Substantial TCE and ammonium contamination was detected in groundwater beneath a residential area in Perth, Western Australia. Investigation has successfully determined broad aspects of the extent of the TCE plume and its impact. The advective front of the plume in groundwater is approximately 600 m downgradient from an industrial area. The contamination is about 300-400 m wide and 6-8 m

E. Benker; G. B. Davis; S. Appleyard; D. A. Barry; T. R. Power

1996-01-01

199

Rocket plume properties measured in space simulators  

NASA Technical Reports Server (NTRS)

Molecular sink facility and 25-foot space simulator have been used to distinguish nature of exhaust plumes from nozzles with relatively large internal boundary layer flow. Plume density has been measured by electron beam/photomultiplier system.

Stephens, J. B.; Herrera, J. G.

1973-01-01

200

Dynamics of laser ablated colliding plumes  

SciTech Connect

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

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

2013-01-15

201

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

202

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

E-print Network

Hudson River flow from USGS Mohawk and Fort Edward gauges + persistence (for forecast) accessed via webModeling 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

Wilkin, John

203

Coastal pollution hazards in southern California observed by SAR imagery: stormwater plumes, wastewater plumes,  

E-print Network

, wastewater plumes, and natural hydrocarbon seeps Paul M. DiGiacomo a,*, Libe Washburn b , Benjamin Holt Abstract Stormwater runoff plumes, municipal wastewater plumes, and natural hydrocarbon seeps are important; Slicks; Southern California; Synthetic aperture radar; Wastewater, plumes 1. Introduction The rapidly

Washburn, Libe

204

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

205

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...

206

Types of thermal plumes in coastal waters  

NASA Technical Reports Server (NTRS)

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

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

1977-01-01

207

Observed Cooling Tower Plume Characteristics.  

National Technical Information Service (NTIS)

In-plume measurements with an instrumented Cessna 411 aircraft were made at the Rancho Seco Nuclear Generating Station (913 MWe) near Sacramento, California; the Trojan nuclear plant (1130 MWe) on the Columbia River 50 mi. north of Portland, Oregon; and t...

M. A. Wolf

1976-01-01

208

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

209

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...

210

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...

211

Heat sources for mantle plumes  

NASA Astrophysics Data System (ADS)

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

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

2008-06-01

212

Hydraulic gradient control for groundwater contaminant removal  

NASA Astrophysics Data System (ADS)

The Rocky Mountain Arsenal near Denver, Colorado, 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.

Atwood, Dorothy Fisher; Gorelick, Steven M.

1985-01-01

213

Turbulent forces within river plumes affect spread  

NASA Astrophysics Data System (ADS)

When rivers drain into oceans through narrow mouths, hydraulic forces squeeze the river water into buoyant plumes that are clearly visible in satellite images. Worldwide, river plumes not only disperse freshwater, sediments, and nutrients but also spread pollutants and organisms from estuaries into the open ocean. In the United States, the Columbia River—the largest river by volume draining into the Pacific Ocean from North America—generates a plume at its mouth that transports juvenile salmon and other fish into the ocean. Clearly, the behavior and spread of river plumes, such as the Columbia River plume, affect the nation's fishing industry as well as the global economy.

Bhattacharya, Atreyee

2012-08-01

214

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

215

Wavefront healing renders deep plumes seismically invisible  

NASA Astrophysics Data System (ADS)

Since W. J. Morgan proposed that intraplate volcanism at some Pacific hotspots is caused by hot plumes rising from the lower mantle, geophysicists have been actively pursuing physical evidence for mantle plumes. Several seismic studies have mapped low-velocity anomalies below a number of hotspots. However, the association of low-velocity structures with plume tails has remained controversial given the debate on whether lower-mantle plumes impart observable traveltime or amplitude perturbations on seismic waves. Using high-resolution numerical simulations of plume ascent through the mantle and their effects on waveforms, we demonstrate that the delay of shear waves by plume tails at depths larger than 1000 km are immeasurably small (<0.2 s) at seismic periods commonly used in waveform analysis. Therefore, we conclude that narrow lower mantle plumes are not detectable.

Hwang, Yong Keun; Ritsema, Jeroen; van Keken, Peter E.; Goes, Saskia; Styles, Elinor

2011-10-01

216

Teaching the Mantle Plumes Debate  

NASA Astrophysics Data System (ADS)

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

Foulger, G. R.

2010-12-01

217

Mixing and deformations in mantle plumes  

NASA Astrophysics Data System (ADS)

The long standing idea that the source of oceanic island basalts includes ancient subducted material is strengthened by recent geochemical observations for Hawaii [Lassiter and Hauri, Earth Planet. Sci. Lett. 164 (1998) 483-496] and Iceland [Kempton et al., Earth Planet. Sci. Lett. 177 (2000) 255-271]. In particular, the isotopic variations in Hawaiian shield lavas indicate the presence of two distinct recycled components: ancient oceanic crust+sediments, and altered ultramafic lower crust or lithospheric mantle. Lassiter and Hauri [Earth Planet. Sci. Lett. 164 (1998) 483-496] suggest that both components are from the same packet of recycled oceanic lithosphere, thus implying that chemical heterogeneities a few km thick can be preserved in the convecting mantle. In this paper we investigate the role of mantle plumes in stirring mantle heterogeneities and we address the following questions: (1) Is the heterogeneous nature of plumes inherited at the source or does it develop through entrainment? (2) Is stirring more efficient in the plume head or in the long-lived plume tail? (3) Are the geochemical implications consistent with fluid dynamical models? We use a three-dimensional numerical model in Cartesian geometry to simulate the dynamics of an isolated plume. Transport calculations, conducted on a vertical plane of symmetry, allow us to advect passive tracers forward or backward in time to investigate mixing. We also calculate the finite-time Lyapunov exponents in order to quantify the deformations associated to the plume rise. Our results show that: (1) the thermal boundary layer, where the plume forms, is the region most efficiently sampled by a mantle plume. Since the overlying mantle is not entrained in the plume head, we speculate that the geochemically heterogeneous nature of plumes is inherited from the source. Our results also predict the absence of present-day upper mantle, source of MORB, in plume lavas. (2) Heterogeneities initially located in the source region undergo a series of stretching and folding events while rising in the plume head and may be reduced to narrow filaments. We find that stirring is more important in the plume head than in the long-lived plume tail. Therefore, our results predict that distinct geochemical heterogeneities are more likely to be found in hotspot lavas rather than in flood basalt lavas, associated to partial melting of a plume tail and a plume head [Richards et al., Science 246 (1989) 103-107], respectively. (3) High Lyapunov exponents, indicating high deformations, are found at the frontier between the plume head and the sublithospheric mantle surrounding the plume head. We speculate that the arrival of a large plume head could induce seismic anisotropy in the shallow upper mantle.

Farnetani, Cinzia G.; Legras, Bernard; Tackley, Paul J.

2002-02-01

218

Delineating Methods of Sample-Size Planning  

E-print Network

Sample-size planning historically has been approached from a power analytic perspective in order to have some reasonable probability of correctly rejecting the null hypothesis. Another approach that is not as wellknown is one that emphasizes accuracy in parameter estimation (AIPE). From the AIPE perspective, sample size is chosen such that the expected width of a confidence interval will be sufficiently narrow. The rationales of both approaches are delineated and two procedures are given for estimating the sample size from the AIPEperspective for a twogroup mean comparison. One method yields the required sample size, such that the expected width of the computed confidence interval will be the value specified. A modification allows for a defined degree of probabilistic assurance that the width of the computed confidence interval will be no larger than specified. The authors emphasize that the correct conceptualization of sample-size planning depends on the research questions and particular goals of the study.

Ken Kelley; Scott E. Maxwell; Joseph R. Rausch

219

Harnessing genomics for delineating conservation units  

PubMed Central

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

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

2014-01-01

220

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

Microsoft Academic Search

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

Thomas B. Curtin; Richard V. Legeckis

1986-01-01

221

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

NASA Astrophysics Data System (ADS)

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.

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

2008-02-01

222

Detection of Wastewater Plumes from the 15 N Isotopic Composition of  

E-print Network

Detection of Wastewater Plumes from the 15 N Isotopic Composition of Groundwater, Algae that a main source of nutrient loading is due to wastewater contamination of groundwater within the watershed via septic systems and wastewater treatment facilities. 5 Mya arenaria were collected at each

Vallino, Joseph J.

223

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...

224

Dispersion controlled natural attenuation : The role of conservative plume characteristics in reactive mixing processes  

Microsoft Academic Search

The aim of this project was to gain a fundamental understanding into competing mixing processes involved in natural\\/enhanced attenuation; processes which occur chiefly in the transition zone of a contaminant plume. Analytical and numerical methods, in combination with laboratory and field data, were employed to quantify these mixing processes. In particular, the focus of this work was on transverse dispersion,

Philip Andrew Sison Ham

2006-01-01

225

Irritants in cigarette smoke plumes  

SciTech Connect

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

Ayer, H.E.; Yeager, D.W.

1982-11-01

226

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

227

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.

228

The influence of commonly used materials and compounds on spacecraft contamination  

Microsoft Academic Search

The effects of molecular contamination on the operation of optical instruments and sensors based on low-earth orbiting spacecraft and platforms and the sensitivity levels of these instruments to contamination are discussed. Material outgassing products and propulsion system plume products are examined as two major sources of spacecraft contamination. The two main mechanism of spacecraft system degradation are contaminants on a

Diane J. Martin; Carl R. Maag

1992-01-01

229

Enhanced biodegradation by hydraulic heterogeneities in petroleum hydrocarbon plumes  

NASA Astrophysics Data System (ADS)

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

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

2009-02-01

230

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

231

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

232

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

2012-06-07

233

Propagation of light through ship exhaust plumes  

NASA Astrophysics Data System (ADS)

Looking through the atmosphere, it is sometimes difficult to see the details of an object. Effects like scintillation and blur are the cause of these difficulties. Exhaust plumes of e.g. a ship can cause extreme scintillation and blur, making it even harder to see the details of what lies behind the plume. Exhaust plumes come in different shapes, sizes, and opaqueness and depending on atmospheric parameters like wind speed and direction, as well as engine settings (power, gas or diesel, etc.). A CFD model is used to determine the plume's flow field outside the stack on the basis of exhaust flow properties, the interaction with the superstructure of the ship, the meteorological conditions and the interaction of ship's motion and atmospheric wind fields. A modified version of the NIRATAM code performs the gas radiation calculations and provides the radiant intensity of the (hot) exhaust gases and the transmission of the atmosphere around the plume is modeled with MODTRAN. This allows assessing the irradiance of a sensor positioned at some distance from the ship and its plume, as function of the conditions that influence the spatial distribution and thermal properties of the plume. Furthermore, an assessment can be made of the probability of detecting objects behind the plume. This plume module will be incorporated in the TNO EOSTAR-model, which provides estimates of detection range and image quality of EO-sensors under varying meteorological conditions.

van Iersel, M.; Mack, A.; van Eijk, A. M. J.; Schleijpen, H. M. A.

2014-10-01

234

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

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

235

An assessment of OAR delineation by the radiation therapist  

Microsoft Academic Search

IntroductionRole expansion of the radiation therapist into areas such as organ at risk (OAR) delineation is currently being discussed. Any role expansion into this area, however, must be carefully monitored and evaluated before it should occur. OAR delineation is a vital link in an effective Image Guided Radiation Therapy (IGRT) and Intensity Modulated Radiation Therapy (IMRT) program. The uniformity of

Karlissa Schick; Toni Sisson; Jim Frantzis; Eric Khoo; Mark Middleton

2011-01-01

236

FLOOD-PLAIN DELINEATION IN ICE JAM PRONE REGIONS  

E-print Network

Flood Insurance Program. However, unique causes of flooding, such as ice jams, have riot receivedFLOOD-PLAIN DELINEATION IN ICE JAM PRONE REGIONS By Richard M. Vogel,1 S. M. ASCE and Jery R. Stedinger,2 A. M. ASCE ABSTRACT:Flood-plain delineation in ice jam prone regions is in its infancy .A

Vogel, Richard M.

237

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

238

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

239

Modeling The Interaction Between a Rocket Plume, Scoured Regolith, and a Plume Deflection Fence  

E-print Network

Modeling The Interaction Between a Rocket Plume, Scoured Regolith, and a Plume Deflection Fence A in the near vicinity of the engine. As the rocket exhaust expands further towards vacuum, continuum As a lunar lander approaches the surface, the rocket engine exhaust plume strikes the ground causing dust

Lightsey, Glenn

240

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

241

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

242

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

243

Plumes or Not? Yes, and Plenty!  

NASA Astrophysics Data System (ADS)

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

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

2004-12-01

244

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

245

VISUAL PLUMES MIXING ZONE MODELING SOFTWARE  

EPA Science Inventory

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

246

The planet beyond the plume hypothesis  

Microsoft Academic Search

Acceptance of the theory of plate tectonics was accompanied by the rise of the mantle plume\\/hotspot concept which has come to dominate geodynamics from its use both as an explanation for the origin of intraplate volcanism and as a reference frame for plate motions. However, even with a large degree of flexibility permitted in plume composition, temperature, size, and depth

Alan D. Smith; Charles Lewis

1999-01-01

247

GK Batchelor The response of a plume  

E-print Network

GK Batchelor Laboratory The response of a plume to a sudden reduction in buoyancy flux Can we strangle a plume? CAMBRIDGE UNIVERSITY OF Stuart Dalziel Matthew Scase Colm-cille Caulfield #12;GK to Shakespeare! #12;GK Batchelor Laboratory great expectations · If buoyancy flux decreased rapidly

Dalziel, Stuart

248

Potential perchlorate exposure from Citrus sp. irrigated with contaminated water  

Microsoft Academic Search

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

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

2006-01-01

249

National Oceanic and Atmospheric Administration \\/NOAA\\/ contamination monitoring instrumentation  

Microsoft Academic Search

The JPL has designed and built a plume contamination monitoring package to be installed on a NOAA environmental services satellite. The package is designed to monitor any condensible contamination that occurs during the ignition and burn of a TE-M-364-15 apogee kick motor. The instrumentation and system interface are described, and attention is given to preflight analysis and test.

C. R. Maag

1980-01-01

250

National Oceanic and Atmospheric Administration /NOAA/ contamination monitoring instrumentation  

NASA Astrophysics Data System (ADS)

The JPL has designed and built a plume contamination monitoring package to be installed on a NOAA environmental services satellite. The package is designed to monitor any condensible contamination that occurs during the ignition and burn of a TE-M-364-15 apogee kick motor. The instrumentation and system interface are described, and attention is given to preflight analysis and test.

Maag, C. R.

1980-01-01

251

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...

252

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

253

Negative ions in the Enceladus plume  

NASA Astrophysics Data System (ADS)

During Cassini's Enceladus encounter on 12th March 2008, the Cassini Electron Spectrometer, part of the CAPS instrument, detected fluxes of negative ions in the plumes from Enceladus. It is thought that these ions include negatively charged water group cluster ions associated with the plume and forming part of the 'plume ionosphere'. In this paper we present our observations, argue that these are negative ions, and present preliminary mass identifications. We also suggest mechanisms for production and loss of the ions as constrained by the observations. Due to their short lifetime, we suggest that the ions are produced in or near the water vapour plume, or from the extended source of ice grains in the plume. We suggest that Enceladus now joins the Earth, Comet Halley and Titan as locations in the Solar System where negative ions have been directly observed although the ions observed in each case have distinctly different characteristics.

Coates, A. J.; Jones, G. H.; Lewis, G. R.; Wellbrock, A.; Young, D. T.; Crary, F. J.; Johnson, R. E.; Cassidy, T. A.; Hill, T. W.

2010-04-01

254

Negative Ions in the Enceladus Plume (Invited)  

NASA Astrophysics Data System (ADS)

During recent Enceladus encounters by Cassini, the Cassini Electron Spectrometer, part of the CAPS instrument, detected fluxes of negative ions in the plumes from Enceladus (Coates et al, Icarus in press, 2009). It is thought that these ions include negatively charged water group cluster ions associated with the plume and forming part of the ‘plume ionosphere’. Here we present our observations, show that these are negative ions, and present preliminary mass identifications. We also suggest mechanisms for production and loss of the ions as constrained by the observations. Due to their short lifetime, we suggest that the ions are produced in or near the water vapour plume, or from the extended source of ice grains in the plume. Enceladus now joins the Earth, comet Halley and Titan as locations in the solar system where negative ions have been directly observed, although the ions observed in each case have distinctly different characteristics.

Coates, A. J.; Jones, G. H.; Lewis, G.; Wellbrock, A.; Young, D. T.; Crary, F. J.; Johnson, R. E.; Hill, T. W.

2009-12-01

255

Plume detachment from a magnetic nozzle  

SciTech Connect

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

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

2009-03-15

256

Entrainment and mixing properties of multiphase plumes: Experimental studies on turbulence and scalar structure of a bubble plume  

E-print Network

-dimensional velocity and concentration fields of multiphase plumes. The developed measurement techniques are applied to bubble plumes in different ambient conditions. The problems and errors in the two-phase PIV application to a bubble plume case are addressed through...

Seol, Dong Guan

2009-05-15

257

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

258

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

259

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

260

Analysis of the distribution of inorganic constituents in a landfill leachate-contaminated aquifer: Astrolabe Park, Sydney, Australia  

Microsoft Academic Search

An investigation was conducted at Astrolabe Park landfill, a decommissioned municipal landfill in Sydney, Australia, to assess the physical and chemical processes affecting the distribution of inorganic constituents in the leachate plume. The plume is migrating from the landfill towards a groundwater-fed pond into which leachate-impacted groundwater discharges. Borehole geophysical logging and depth-discrete groundwater sampling were used to delineate the

L. B. Jorstad; J. Jankowski; R. I. Acworth

2004-01-01

261

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

262

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

263

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

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

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

264

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

265

18 CFR 415.43 - Mapped and unmapped delineations.  

...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

266

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

267

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

268

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

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

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

269

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

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

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

270

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

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

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

271

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

272

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

273

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

E-print Network

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

Watson, Samuel Jewell

2012-06-07

274

A numerical study of the Magellan Plume  

NASA Astrophysics Data System (ADS)

In this modeling study we investigate the dynamical mechanisms controlling the spreading of the Magellan Plume, which is a low-salinity tongue that extends along the Patagonian Shelf. Our results indicate that the overall characteristics of the plume (width, depth, spreading rate, etc.) are primarily influenced by tidal forcing, which manifests through tidal mixing and tidal residual currents. Tidal forcing produces a homogenization of the plume's waters and an offshore displacement of its salinity front. The interaction between tidal and wind-forcing reinforces the downstream and upstream buoyancy transports of the plume. The influence of the Malvinas Current on the Magellan Plume is more dominant north of 50°S, where it increases the along-shelf velocities and generates intrusions of saltier waters from the outer shelf, thus causing a reduction of the downstream buoyancy transport. Our experiments also indicate that the northern limit of the Magellan Plume is set by a high salinity discharge from the San Matias Gulf. Sensitivity experiments show that increments of the wind stress cause a decrease of the downstream buoyancy transport and an increase of the upstream buoyancy transport. Variations of the magnitude of the discharge produce substantial modifications in the downstream penetration of the plume and buoyancy transport. The Magellan discharge generates a northeastward current in the middle shelf, a recirculation gyre south of the inlet and a region of weak currents father north.

Palma, Elbio D.; Matano, Ricardo P.

2012-05-01

275

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

276

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

277

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

278

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

279

Significance of Surgical Plume Obstruction During Laparoscopy  

PubMed Central

With the advent of laparoscopic surgery, the need of optimal visualization and efficient instrumentation has created a need for better understanding of the characteristics of the surgical plume. Despite the technological advances of digital imaging and dissector technology (ultrasonic, radiofrequency electrical, and bipolar), the inconvenient and sometimes harmful generation of a surgical plume decreases visualization, often requiring the surgeon to remove the scope from the surgical field and remove the obstructing particles. If visualization is suboptimal or lost during bleeding, the outcome can be deadly. Therefore, we reviewed the available reports in the literature focused on the quantification of surgical plumes. PMID:25419108

da Silva, Rodrigo Donalisio; Sehrt, David; Molina, Wilson R.; Moss, Jake; Park, Sang Hyun

2014-01-01

280

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

281

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

NASA Astrophysics Data System (ADS)

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

Zamfirescu, Daniela; Grathwohl, Peter

2001-12-01

282

Ozone formation in pollutant plumes: a reactive plume model with arbitrary crosswind resolution. Final report  

SciTech Connect

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 Lagrangian downwind transport and Wulerian crosswind spread. It is applied in a diagnostic mode to simulate the observed behavior of plumes of the metropolitan St. Louis area and the Labadie power plant. The RAPS emissions inventory gave detailed spatial resolution of the emission field, numerous stationary and mobile upper air wind soundings provided the basis for transport simulation, and aircraft data provided detailed crosswind profiles of pollutant concentrations across the plumes at downwind sections. Model simulations of ozone were generally good, even in crosswind detail, given an appropriate background characterization. Simulated values of the rate of SO/sub 2/ oxidation were quantitatively not as satisfying.

Gillani, N.V.

1986-08-01

283

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 ...

284

A bi-directional river plume: The Columbia in summer  

Microsoft Academic Search

Freshwater plumes have important effects on marine ecosystems: in the presence of a plume, stratification, nutrient pathways, light and circulation patterns are significantly altered from patterns that occur under the influence of wind and ambient currents alone. The historical picture of the plume from the Columbia River is of a freshwater plume oriented southwest offshore of the Oregon shelf in

B. Hickey; S. Geier; N. Kachel; A. MacFadyen

2005-01-01

285

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

286

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

287

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

288

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

Microsoft Academic Search

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

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

2005-01-01

289

Hyperspectral chemical plume quantification via background radiance estimation  

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

290

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

291

Sampling Particles In Hot Gas Plumes  

NASA Technical Reports Server (NTRS)

Sampling darts and launching apparatus built to collect particles in vertical plume of hot gas. In original application, hot gas plume is rocket-engine exhaust during test firing. Dart passes made at various heights, depending on launch angle and launch-gas pressure. Adaptable to variety of terrestrial uses like research on particulate emissions of volcanoes or determining origin of building fire while still burning.

Taylor, James F.; Sambamurthi, Jay

1994-01-01

292

Scales of variability of black carbon plumes  

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

293

Cretaceous Arctic magmatism: Slab vs. plume? Or slab and plume?  

NASA Astrophysics Data System (ADS)

Tectonic models for the Cretaceous paleogeographic evolution of the Arctic Ocean and its adjacent landmasses propose that rifting in the Amerasia Basin (AB) began in Jura-Cretaceous time, accompanied by the development of the High Arctic Large Igneous Province (HALIP). During the same timespan, deformation and slab-related magmatism, followed by intra-arc rifting, took place along the Pacific side of what was to become the Arctic Ocean. A compilation and comparison of the ages, characteristics and space-time variation of circum-Arctic magmatism allows for a better understanding of the role of Pacific margin versus Arctic-Atlantic plate tectonics and the role of plume-related magmatism in the origin of the Arctic Ocean. In Jura-Cretaceous time, an arc built upon older terranes overthrust the Arctic continental margins of North America and Eurasia, shedding debris into foreland basins in the Brooks Range, Alaska, across Chukotka, Russia, to the Lena Delta and New Siberian Islands region of the Russian Arctic. These syn-tectonic sediments have some common sources (e.g., ~250-300 Ma magmatic rocks) as determined by U-Pb detrital zircon geochronology. They are as young as Valanginian-Berriasian (~136 Ma, Gradstein et al., 2004) and place a lower limit on the age of formation of the AB. Subsequent intrusions of granitoid plutons, inferred to be ultimately slab-retreat related, form a belt along the far eastern Russian Arctic continental margin onto Seward Peninsula and have yielded a continuous succession of zircon U-Pb ages from ~137-95 Ma (n=28) and a younger suite ~91-82 Ma (n=16). All plutons dated were intruded in an extensional tectonic setting based on their relations to wall-rock deformation. Regional distribution of ages shows a southward migration of the locus of magmatism during Cretaceous time. Basaltic lavas as old as 130 Ma and as young as 80 Ma (40Ar/39Ar)) erupted across the Canadian Arctic Islands, Svalbard and Franz Josef Land and are associated with radial dikes that emanate from the proposed locus of the HALIP on the Alpha Ridge (Buchan and Ernst, 2006). 112, 100, and 83 Ma (40Ar/39Ar) basaltic lavas dredged in 2008 from the northwestern edge of the Canada Basin bear geochemical similarity to HALIP magmatism on Ellesmere Island and Franz Josef Land. Geochemical data on terrestrial HALIP and dredged basalts is indicative of an evolving plume-related origin for basaltic magmatism by 112 Ma. No matter how the AB is reconstructed, its pre-mid-Cretaceous configuration requires that terrestrial exposures of the HALIP were much closer to the actively subducting and extending Russian-Alaskan margin. Likewise, the temporal overlap of the onset of extension along the Russian-Alaskan segment of the Arctic margin (~135-120 Ma) with eruption of Barremian-Aptian HALIP lavas needs to be considered in models for the opening of the AB. This geochronologic compilation and summary highlights the facts that before the opening of the AB, the HALIP originated in a back arc position with respect to slab-related magmatism along the Pacific margin of the Arctic and that the two types of magmatism overlap in age and were once closer in space.

Gottlieb, E. S.; Miller, E. L.; Andronikov, A. V.; Brumley, K.; Mayer, L. A.; Mukasa, S. B.

2010-12-01

294

Vertical distribution of Pahang River plume  

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

295

Confirmation of Europa's water vapor plume activity  

NASA Astrophysics Data System (ADS)

STIS spectral UV images of Jupiter's satellite Europa obtained during HST Cycle 20 revealed atomic H and O auroral emissions in intensity ratios which uniquely identify the source as electron impact excitation of water molecules above Europa's south pole and hypothesized to be associated with water vapor plumes as reported in Roth et al., Science, 2014. The plumes were detected when Europa was at apocenter on December 30/31, 2012. Two other sets of STIS observations when Europa was near pericenter did not show plume emission within the sensitivity of STIS. The plume variability is predicted to be correlated with Europa's distance from Jupiter in the observed way. However, the one plume detection at apocenter and the two non-detections near pericenter require confirmation. Therefore we request two visits of 5 orbits each to observe Europa at orbital positions of the predicted maximum plume activity {similar to the December 2012 STIS Europa visit} to provide confirmation of the initial STIS discovery and to consolidate the predicted geophysical variability pattern.

Roth, Lorenz

2013-10-01

296

Nuclear thermal rocket plume interactions with spacecraft. Final report  

SciTech Connect

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

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

1997-05-01

297

An Organic Carbon Budget for the Mississippi River Turbidity Plume and Plume Contributions to Air-sea CO2 Fluxes and  

E-print Network

An Organic Carbon Budget for the Mississippi River Turbidity Plume and Plume Contributions to Air for the Mississippi River turbidity plume. Plume volume was calculated from mixed layer depth and area in each of four

Breed, Greg A.

298

Automated tree crown delineation from imagery based on morphological techniques  

NASA Astrophysics Data System (ADS)

In current tree crown delineation from imagery, treetops and three dimensional (3D) radiometric shapes of tree crowns are frequently extracted from a spectral band or a brightness component of the image and taken as references to localize and delineate tree crowns. However, color components of the image are rarely used together with the brightness component of the image to facilitate localizing and delineating crowns. The 3D radiometric shape of a crown can be derived from a brightness or color component and may be taken as a half-ellipsoid. From top to bottom of such a half-ellipsoid, multiple horizontal slices can be drawn, contain the treetop, and indicate both the location and the horizontal extent of the crown. Based on such a concept of horizontal slices of crowns, a novel multi-scale method for individual tree crown delineation from imagery was proposed in this study. In this method, the brightness and color components of the image are morphologically opened within the scale range of target crowns, horizontal slices of target crowns are extracted from the resulting opened images and integrated together to localize crowns, and one component is segmented using the watershed approach with reference to the integrated slices. In an experiment on high spatial resolution aerial imagery over natural closed canopy forests, the proposed method correctly delineated approximately 74% of mixedwood tree crowns and 59% of deciduous crowns in the natural forests.

Jing, L.; Hu, B.; Li, J.; Noland, T.; Guo, H.

2014-03-01

299

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

300

Plume and lithologic profiling with surface resistivity and seismic tomography.  

PubMed

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

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

2005-01-01

301

Plume and lithologic profiling with surface resistivity and seismic tomography  

SciTech Connect

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

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

2005-03-01

302

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

NASA Technical Reports Server (NTRS)

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

Jackson, Mark Charles

1994-01-01

303

OBSERVATION OF HIGH-SPEED OUTFLOW ON PLUME-LIKE STRUCTURES OF THE QUIET SUN AND CORONAL HOLES WITH SOLAR DYNAMICS OBSERVATORY/ATMOSPHERIC IMAGING ASSEMBLY  

SciTech Connect

Observations from the Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory reveal ubiquitous episodic outflows (jets) with an average speed around 120 km s{sup -1} at temperatures often exceeding a million degree in plume-like structures, rooted in magnetized regions of the quiet solar atmosphere. These outflows are not restricted to the well-known plumes visible in polar coronal holes, but are also present in plume-like structures originating from equatorial coronal holes and quiet-Sun (QS) regions. Outflows are also visible in the 'inter-plume' regions throughout the atmosphere. Furthermore, the structures traced out by these flows in both plume and inter-plume regions continually exhibit transverse (Alfvenic) motion. Our finding suggests that high-speed outflows originate mainly from the magnetic network of the QS and coronal holes (CHs), and that the plume flows observed are highlighted by the denser plasma contained therein. These outflows might be an efficient means to provide heated mass into the corona and serve as an important source of mass supply to the solar wind. We demonstrate that the QS plume flows can sometimes significantly contaminate the spectroscopic observations of the adjacent CHs-greatly affecting the Doppler shifts observed, thus potentially impacting significant investigations of such regions.

Tian Hui; McIntosh, Scott W. [High Altitude Observatory, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307 (United States); Habbal, Shadia Rifal [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); He Jiansen, E-mail: htian@ucar.edu, E-mail: mscott@ucar.edu, E-mail: shadia@ifa.hawaii.edu, E-mail: jshept@gmail.com [School of Earth and Space Sciences, Peking University, 100871 Beijing (China)

2011-08-01

304

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

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

305

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

Microsoft Academic Search

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

Jonathan A. Warrick; Andrew W. Stevens

2011-01-01

306

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

E-print Network

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

307

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

EPA Science Inventory

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

308

CORONAL PLUMES IN THE FAST SOLAR WIND  

SciTech Connect

The expansion of a coronal hole filled with a discrete number of higher density coronal plumes is simulated using a time-dependent two-dimensional code. A solar wind model including an exponential coronal heating function and a flux of Alfven waves propagating both inside and outside the structures is taken as a basic state. Different plasma plume profiles are obtained by using different scale heights for the heating rates. Remote sensing and solar wind in situ observations are used to constrain the parameter range of the study. Time dependence due to plume ignition and disappearance is also discussed. Velocity differences of the order of {approx}50 km s{sup -1}, such as those found in microstreams in the high-speed solar wind, may be easily explained by slightly different heat deposition profiles in different plumes. Statistical pressure balance in the fast wind data may be masked by the large variety of body and surface waves which the higher density filaments may carry, so the absence of pressure balance in the microstreams should not rule out their interpretation as the extension of coronal plumes into interplanetary space. Mixing of plume-interplume material via the Kelvin-Helmholtz instability seems to be possible within the parameter ranges of the models defined here, only at large distances from the Sun, beyond 0.2-0.3 AU. Plasma and composition measurements in the inner heliosphere, such as those which will become available with Solar Orbiter and Solar Probe Plus, should therefore definitely be able to identify plume remnants in the solar wind.

Velli, Marco [Jet Propulsion Laboratory, Pasadena, CA 91109 (United States); Lionello, Roberto; Linker, Jon A.; Mikic, Zoran, E-mail: mvelli@mail.jpl.nasa.gov, E-mail: lionel@predsci.com, E-mail: linkerj@predsci.com, E-mail: mikicz@predsci.com [Predictive Science, Inc., San Diego, CA 92121-2910 (United States)

2011-07-20

309

Delineation of LASIK Flaps with Prednisolone Acetate Eyedrops  

PubMed Central

We describe the use and safety of prednisolone acetate eyedrops at the end of laser in situ keratomileusis (LASIK) to aid proper positioning of the corneal flap. The LASIK flap is created using the preferred technique. Following laser ablation and flap repositioning, one drop of prednisolone acetate is instilled on the eye. This delineates the flap “gutters” and allows perfect flap positioning and centration. We used this technique in 425 eyes undergoing LASIK for correction of spherocylindrical refractive errors. Flap margins were adequately delineated intraoperatively. The only complication related to the use of the steroid suspension was crystal deposition under the flap in one case which resolved completely in 48 hours. PMID:24982743

Fahd, Daoud C; Fahed, Sharbel D

2014-01-01

310

Multiscale Hydrogeophysical Data Assimilation for Plume-Scale Subsurface Characterization  

NASA Astrophysics Data System (ADS)

Predictions of subsurface contaminant plume evolution and natural attenuation capacity often fail due to the difficulty to tractably characterize heterogeneity of flow-and-transport properties at the plume-relevant scales. This study presents a stochastic-estimation framework for assimilating multiscale datasets and characterizing a plume-scale subsurface domain. We utilize the concept of reactive facies, which is based on the hypothesis that we can identify packages of sediments that have distinct distributions of properties influencing reactive transport, such as effective surface area, mineralogy and permeability. Because geophysical attributes are often sensitive to some of those properties, this concept allows us to take advantage of both geophysical and lithological datasets, to characterize the spatial distribution of reactive transport parameters. Previous research has illustrated that crosshole geophysical methods can be used to identify and spatially distribute reactive facies at the local scale. To map the spatial distribution of reactive facies at the plume-scale, we must (1) honor the large-scale trend without smoothing out the detail structure of facies, and (2) assimilate multi-source, multiscale datasets in a consistent manner, including wellbore data and crosshole and surface geophysical data. To tackle these challenges, we have developed a hierarchical Bayesian framework, which consists of three statistical sub-models: a data model, a process model, and a prior model. The data model - developed according to the stochastic feature of measurement errors - provides the linkage between the multiple geophysical datasets and the spatially distributed geophysical attributes through linear/nonlinear forward models. The process model describes the spatial distribution of reactive facies and geophysical attributes as spatial random processes controlled by geostatistical and petrophysical parameters. We use an indicator random field with a trend function for facies and Gaussian fields for geophysical attributes within each facies. The prior model is constructed for the controlling parameters based on the information from geologically similar sites. Using the Markov-chain Monte-Carlo sampling method, we obtain the marginal posterior distribution of parameters and reactive facies fields that can be used as an input to reactive transport simulations. We apply our framework to the datasets from the uranium-contaminated Savannah River Site F-Area. They include wellbore lithology data, cone penetration test data, crosshole ground-penetrating radar and seismic data, and surface seismic data. A synthetic study with the same data acquisition setup shows that the point-scale and crosshole data provide the detailed structure of reactive facies, and reduce uncertainty significantly in their vicinity, while surface seismic data can identify the large-scale trend and map facies with increased uncertainty over a large domain. We find that our methodology effectively integrates different types of data, providing an approach for distributing critical information about properties that control flow and transport (typically obtained at the core/well scale) to the scales needed for simulating plume migration and remediation.

Wainwright, H. M.; Sassen, D. S.; Chen, J.; Hubbard, S. S.

2011-12-01

311

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

NASA Astrophysics Data System (ADS)

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

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

2007-12-01

312

Crater Formation Due to Lunar Plume Impingement  

NASA Technical Reports Server (NTRS)

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

Marsell, Brandon

2011-01-01

313

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

ERIC Educational Resources Information Center

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

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

2011-01-01

314

Quantitative comparison of delineated structure shape in radiotherapy  

NASA Astrophysics Data System (ADS)

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

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

2006-03-01

315

Tidal networks 2. Watershed delineation and comparative network morphology  

E-print Network

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

Fagherazzi, Sergio

316

362. Delineator Unknown June 1933 STATE OF CALIFORNIA; DEPARTMENT OF ...  

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

362. Delineator Unknown June 1933 STATE OF CALIFORNIA; DEPARTMENT OF PUBLIC WORKS; SAN FRANCISCO - OAKLAND BAY BRIDGE; SAN FRANCISCO ANCHORAGE; EYE BAR ANCHOR CHAIN; CONTRACT NO. 3; SUP. DRAWING NO. 11-A - San Francisco Oakland Bay Bridge, Spanning San Francisco Bay, San Francisco, San Francisco County, CA

317

374. Delineator Unknown June 1933 STATE OF CALIFORNIA; DEPARTMENT OF ...  

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

374. Delineator Unknown June 1933 STATE OF CALIFORNIA; DEPARTMENT OF PUBLIC WORKS; SAN FRANCISCO - OAKLAND BAY BRIDGE; YERBA BUENA CROSSING; EYE BAR CHAIN; CONTRACT NO. 5; SUP. DRAWING NO. 12A - San Francisco Oakland Bay Bridge, Spanning San Francisco Bay, San Francisco, San Francisco County, CA

318

Delineation of Preventative Landslide Buffers Along Steep Streamside Slopes in  

E-print Network

213 Delineation of Preventative Landslide Buffers Along Steep Streamside Slopes in Northern Co (GDRCo) applies tree retention buffers to steep slopes along fish bearing (Class I) and non with timber harvest plans. These Steep Streamside Slope (SSS) buffers were designed to reduce the amount

Standiford, Richard B.

319

A Method of Delineation of Homogeneous Social-Ecological Areas.  

ERIC Educational Resources Information Center

The traditional dichotomies of urban and rural may no longer be valid. Investigating whether or not there are socially significant areal units to redefine rural and urban areas, the report described one attempt to delineate such units and to test them for sociological utility. Counties were placed in homogeneous social units based upon the…

Loebl, Andrew S.; Campbell, Rex R.

320

Delineating psychomotor slowing from reduced processing speed in schizophrenia  

Microsoft Academic Search

Introduction. Psychomotor slowing is an intrinsic feature of schizophrenia that is poorly delineated from generally reduced processing speed. Although the Symbol Digit Substitution Test (SDST) is widely used to assess psychomotor speed, the task also taps several higher-order cognitive processes. Recording motor performance on copying tasks using a digitising tablet allows a more precise measurement of psychomotor speed.Methods. A group

M. Morrens; W. Hulstijn; C. Matton; Y. Madani; L. van Bouwel; J. Peuskens; B. G. C. Sabbe

2008-01-01

321

Automated Delineation of Dendritic Networks in Noisy Image Stacks  

E-print Network

the dendritic trees of neurons automatically by enforcing the tree structure of the resulting graph. We to reconstruct dendritic trees and rely heavily on manual operations for initialization and re-initialization of the delineation proce- dures. As a result, tracing dendritic trees in noisy images remains a tedious process

Fleuret, François

322

Delineating wetlands using geographic information system and remote sensing technologies  

E-print Network

accurate monitoring of wetland as a less time-consuming method. With this idea, a suitability model was developed to delineate wetlands in the Houston area. This model combined GIS and remote sensing technologies. The data used for this study were as high...

Villeneuve, Julie

2006-04-12

323

PET functional volume delineation: a robustness and repeatability study  

E-print Network

1 PET functional volume delineation: a robustness and repeatability study Mathieu Hatt1 , Ph: Robustness of functional volume determination in PET Keywords: PET uptake volume determination, robustness;2 Abstract Purpose: Current state of the art algorithms for functional uptake volume segmentation in PET

Boyer, Edmond

324

Anisotropy Creases Delineate White Matter Structure in Diffusion Tensor MRI  

E-print Network

Anisotropy Creases Delineate White Matter Structure in Diffusion Tensor MRI Gordon Kindlmann1, University of Utah, USA Abstract. Current methods for extracting models of white matter architecture from for extracting a skeleton of white matter pathways, in that ridges of anisotropy coincide with interiors of fiber

Utah, University of

325

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

326

Properties of industrial dense gas plumes  

NASA Astrophysics Data System (ADS)

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

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

327

Human Papillomavirus DNA in LEEP Plume  

PubMed Central

Objective: This study was undertaken to determine the prevalence of human papillomavirus (HPV) in loop electrosurgical excision procedure (LEEP) plumes. Methods: Forty-nine consecutive patients with colposcopic and cytologic evidence of cervical intraepithelial neoplasia (CIN) were tested. Smoke plumes were collected through a filter placed in the suction tubing. DNA was harvested by proteinase K digest of the filters and prepared for polymerase chain reaction (PCR) by L1 consensus primers. Results: Thirty-nine (80%) tissue samples were positive for HPV, with types 6/11 in 4, 16/18 in 19, 31/33/35 in 2, and other types in 6 patients. The tissue sample was inadequate for typing in 8 patients. HPV DNA was detected in 18 (37%) filters. Conclusions: Although the consequences of HPV in LEEP plume are unknown, it would be prudent to adopt stringent control procedures. PMID:18475386

Bahrani-Mostafavi, Zahra; Stoerker, Jay; Stone, I. Keith

1994-01-01

328

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

329

Enceladus Plumes: A Boiling Liquid Model  

NASA Astrophysics Data System (ADS)

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

Nakajima, Miki; Ingersoll, A. P.

2012-10-01

330

In situ signatures of residual plasmaspheric plumes: Observations and simulation  

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

331

The interaction of the atmosphere with the space shuttle thruster plume: The NH (A-X) 336-nm emission  

NASA Astrophysics Data System (ADS)

Observations of the optical emissions from the space shuttle's thrusters have been examined. Particular attention has been paid to the interaction of the thruster plume with the atmosphere. Emissions from CN, CH, C2, HNO, and NO2 have been observed near the nozzle of the thruster in the vacuum core region of the plume, but these emissions are the direct result of the combustion process. Other emissions including OI and NH have been observed in the downstream region of the plume, where the plume effluents interact with the atmosphere. The NH emission is one of the most dominant UV/visible wavelength emissions observed in the plumes. This emission was observed to extend several thousand meters from the shuttle, and detailed analysis shows that the total intensity of the emission depends on the ram angle (angle in the shuttle reference frame between the plume effluents and the ramming atmosphere) and altitude, indicating an interaction process with the atmosphere. Data from two observational experiments are presented. The Air Force Maui Optical Site (AMOS) experiment includes ground-based spectral and spatial measurements of the shuttle plumes as the thrusters were fired over the AMOS site on top of Haliakala Volcano on the island of Maui in the mid-Pacific. The GLO experiment was flown in the payload bay of the space shuttle and also includes spectral and spatial measurements of the shuttle plumes. During both of these experiments, the primary reaction control system (PRCS) engines (870 lb (394 kgf) thrust) and Vernier reaction control system (VRCS) engines (25 lb (11 kgf) thrust) were fired at various angles relative to the ram, thus providing a range of collision velocities (4.5-11 km/s) between the thruster plume and the atmosphere. In this report the dependence of the NH emission on ram angle, thruster size, and distance from the shuttle is presented and analyzed using a three-dimensional Monte Carlo simulation of the plume-atmosphere interactions called spacecraft/orbiter contamination representation accounting for transiently emitted species (SOCRATES). The chemical reactions deemed most likely involve collisions of the plume products HNC, HNCO, and CH2NH with atmospheric O, and all of these processes are examined. The ram-angle dependence is used to determine a threshold energy required for the reaction that leads to the NH emission and to conclude that the most likely reaction involves CH2NH collisions with O.

Viereck, Rodney A.; Murad, Edmond; Knecht, David J.; Pike, Charles P.; Bernstein, Lawrence S.; Elgin, James B.; Broadfoot, A. Lyle

1996-03-01

332

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

USGS Publications Warehouse

Small rivers commonly discharge into coastal settings with topographic complexities - such as headlands and islands - but these settings are underrepresented in river plume studies compared to more simplified, straight coasts. The Elwha River provides a unique opportunity to study the effects of coastal topography on a buoyant plume, because it discharges into the Strait of Juan de Fuca on the western side of its deltaic headland. Here we show that this headland induces flow separation and transient eddies in the tidally dominated currents (O(100. cm/s)), consistent with other headlands in oscillatory flow. These flow conditions are observed to strongly influence the buoyant river plume, as predicted by the "small-scale" or "narrow" dynamical classification using Garvine's (1995) system. Because of the transient eddies and the location of the river mouth on the headland, flow immediately offshore of the river mouth is directed eastward twice as frequently as it is westward. This results in a buoyant plume that is much more frequently "bent over" toward the east than the west. During bent over plume conditions, the plume was attached to the eastern shoreline while having a distinct, cuspate front along its westernmost boundary. The location of the front was found to be related to the magnitude and direction of local flow during the preceding O(1. h), and increases in alongshore flow resulted in deeper freshwater mixing, stronger baroclinic anomalies, and stronger hugging of the coast. During bent over plume conditions, we observed significant convergence of river plume water toward the frontal boundary within 1. km of the river mouth. These results show how coastal topography can strongly influence buoyant plume behavior, and they should assist with understanding of initial coastal sediment dispersal pathways from the Elwha River during a pending dam removal project. ?? 2010.

Warrick, J. A.; Stevens, A. W.

2011-01-01

333

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

NASA Astrophysics Data System (ADS)

Small rivers commonly discharge into coastal settings with topographic complexities - such as headlands and islands - but these settings are underrepresented in river plume studies compared to more simplified, straight coasts. The Elwha River provides a unique opportunity to study the effects of coastal topography on a buoyant plume, because it discharges into the Strait of Juan de Fuca on the western side of its deltaic headland. Here we show that this headland induces flow separation and transient eddies in the tidally dominated currents (O(100 cm/s)), consistent with other headlands in oscillatory flow. These flow conditions are observed to strongly influence the buoyant river plume, as predicted by the "small-scale" or "narrow" dynamical classification using Garvine's (1995) system. Because of the transient eddies and the location of the river mouth on the headland, flow immediately offshore of the river mouth is directed eastward twice as frequently as it is westward. This results in a buoyant plume that is much more frequently "bent over" toward the east than the west. During bent over plume conditions, the plume was attached to the eastern shoreline while having a distinct, cuspate front along its westernmost boundary. The location of the front was found to be related to the magnitude and direction of local flow during the preceding O(1 h), and increases in alongshore flow resulted in deeper freshwater mixing, stronger baroclinic anomalies, and stronger hugging of the coast. During bent over plume conditions, we observed significant convergence of river plume water toward the frontal boundary within 1 km of the river mouth. These results show how coastal topography can strongly influence buoyant plume behavior, and they should assist with understanding of initial coastal sediment dispersal pathways from the Elwha River during a pending dam removal project.

Warrick, Jonathan A.; Stevens, Andrew W.

2011-02-01

334

Entrainment in two coalescing axisymmetric turbulent plumes  

E-print Network

water (Figure 5). In order to generate turbulent plumes from the sources, the same special nozzles (designed by Dr. Paul Cooper) used by KL04 were employed. The flow rate and density of the salt solution were chosen such that the turbulent plumes had a... ridges from hydrothermal vents (Baker et al. 1995; Speer & Rona 1989) and they are occasionally observed to coalesce. Coastal cities often discharge their partially treated waste waters at the bottom of the ocean via an outfall. Ocean outfall design...

Cenedese, Claudia; Linden, P. F.

2014-07-11

335

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

EPA Science Inventory

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

336

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

NASA Astrophysics Data System (ADS)

A capture zone is the aquifer volume through which ground-water flows to a pumping well over a given time of travel. Determining a well's capture zone aids in water-supply management by creating an awareness of the water source. This helps ensure sustainable pumping operations and outlines areas where protection from contamination is critical. We are delineating the capture zones of hypothetical conceptual models that resemble the Fairbanks, Alaska floodplain both in aquifer parameters and boundary conditions. We begin with a very simple hydrogeologic system and gradually add complexity such as heterogeneity, anisotropy, multiple wells, and zones of permafrost. Commonly-used delineation methods are applied to each case. These include calculated fixed-radius, analytical and numerical models. The calculated fixed-radius method uses a mathematical equation with several simplifying assumptions. Analytical techniques employ a series of equations that likewise assume simple conditions, although to a lesser degree than the fixed-radius method. Our chosen numerical model is MODFLOW-2000, which offers a particle-tracking package (MODPATH) for delineating recharge areas. The delineations are overlayed for each conceptual model in order to compare the capture zones produced by the different methods. Contrasts between capture zones increase with the complexity of the hydrogeology. Simpler methods are restricted by their underlying assumptions. When methods can no longer account for complexities in the conceptual model, the resulting delineations remain similar to those of simpler models. Meanwhile, the zones generated by more sophisticated methods are able to change with changes to the conceptual model. Hence, the simpler methods now lack accuracy and credibility. We have found that these simpler techniques tend to overestimate the capture zone. Water-supply managers must consider such inaccuracies when evaluating the costs of each method. In addition to comparing delineation methods, we are using the series of hypothetical MODFLOW cases to aid in modeling a site within the Fairbanks floodplain. We learn how the site-specific complexities may affect the capture zone by examining the effect of each modification to the hypothetical models. The area is located on Fort Wainwright, AK and consists of multiple water-supply wells. They are screened through a formation known as the Chena Alluvium, which is composed of braided-stream deposits. The wells supply water to a power plant for cooling and to a water treatment plant for drinking water use. The power plant discharges heated water into a cooling pond while the water treatment plant releases back-wash water into a small discharge pond. The Chena River is also nearby, approximately 0.4 km from the wells. Data available from the pumping-well facilities, observation wells, and geologic logs are used to determine input parameters for the model.

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

2003-12-01

337

Experimental and theoretical characterization of a Hall thruster plume  

E-print Network

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

Azziz, Yassir, 1979-

2007-01-01

338

RESEARCH ARTICLE Optical plume velocimetry: a new flow measurement technique  

E-print Network

RESEARCH ARTICLE Optical plume velocimetry: a new flow measurement technique for use in seafloor collected in these environments. We develop a non- invasive method, called optical plume velocimetry (OPV

Wilcock, William

339

Method to attenuate U(VI) mobility in acidic waste plumes using humic acids.  

PubMed

Acidic uranium (U) groundwater 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/year) show that desorption of U and HA were nondetectable 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 indicate 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. PMID:21319737

Wan, Jiamin; Dong, Wenming; Tokunaga, Tetsu K

2011-03-15

340

Nanoparticle plume dynamics in femtosecond laser ablation of gold  

NASA Astrophysics Data System (ADS)

This paper describes some recent results on femtosecond laser ablation of gold. We have studied both the fast vapour/plasma and slow nanoparticle plumes using Langmuir probe, time-resolved ICCD imaging and time-resolved optical absorption measurements. The nanoparticle plume dynamics was analysed by comparing the optical emission absorption measurements with an adiabatic isentropic model of ablation plume expansion, leading to an estimate of the amount of material in the nanoparticle plume.

O'Connell, G.; Donnelly, T.; Lunney, J. G.

2014-10-01

341

Distribution of DDT and other persistent organic contaminants in Canyons and on the continental shelf off the central California coast  

Microsoft Academic Search

Sediment samples were collected to delineate the distribution of contaminants along the central California coast. Sampling included a variety of Canyons and shelf\\/slope areas to evaluate contaminant transport patterns and potential delivery to Canyons and the continental slope to a depth of 1200m. Sediments were collected and analyzed for organic contaminants using standard techniques of the NOAA National Status and

S. Ian Hartwell

2008-01-01

342

Contamination control for the space infrared observatory SPICA  

NASA Astrophysics Data System (ADS)

The contamination control for the next-generation space infrared observatory SPICA is presented. The optical performance of instruments on space observatories are often degraded by particulate and/or molecular contamination. Therefore, the contamination control has a potential to produce a significant risk, and it should be investigated in the risk mitigation phase of the SPICA development. The requirements from contamination- sensitive components onborad SPICA, the telescope assembly and focal plane instruments, are summarized. Possible contamination sources inside and outside the SPICA spacecraft were investigated. Based on impact on the SPICA system design, the following contamination sources were extensively studied through simulation and measurement; (1) outgassing from the payload module surrounding the telescope mirror and focal plane instruments, (2) contamination due to the thruster plume, and (3) environmental contamination during the integration, storage and verification phases. Although the outgas from the payload module and the thruster plume were estimated to produce only a negligible influence, the environmental contamination was suggested to affect significantly the telescope and focal plane instruments. Reasonable countermeasures to reduce the environmental contamination were proposed, some of which were confirmed to be actually effective.

Isobe, Naoki; Nakagawa, Takao; Okazaki, Shun; Sato, Yoichi; Ando, Makiko; Baba, Susumu; Miura, Yuka; Miyazaki, Eiji; Kimoto, Yugo; Ishizawa, Junichiro; Tani, Hiroumi; Maruyama, Kenta; Urayama, Fumitaka; Mori, Akihito

2014-08-01

343

Transmittance and Radiance Computations for Rocket Engine Plume Environments  

NASA Technical Reports Server (NTRS)

Emission and absorption characteristics of several atmospheric and combustion species have been studied and are presented with reference to rocket engine plume environments. The effects of clous, rain, and fog on plume radiance/transmittance has also been studied.Preliminary results for the radiance from the exhaust plume of the space shuttle main engine are shown and discussed.

Tejwani, Gopal D.

2003-01-01

344

El Chichon: composition of plume gases and particles  

Microsoft Academic Search

Aircraft measurements were made of trace gases, atmospheric particles, and condensed acid volatiles in the plume of El Chichon volcano, Chiapas, Mexico, in November 1982. Hydrogen sulfide was the primary gaseous sulfur species in the plume at the time of collection. Concentrations of 28 elements were determined by neutron activation analysis of particulate material from the plume. Rates of trace

J. P. Kotra; D. L. Finnegan; W. H. Zoller; M. A. Hart; J. L. Moyers

1983-01-01

345

Plume Modeling and Application to Mars 2001 Odyssey Aerobraking  

Microsoft Academic Search

A modified source flow model was used to calculate the plume flowfield from a Mars Odyssey thruster during aerobraking. The source flow model results compared well with previous detailed computational-fluid-dynamics results for a Mars Global Surveyor thruster. Using an isodensity surface for the Odyssey plume, direct simulation Monte Carlo simulations were performed to determine the effect the plumes have on

Zachary Q. Chavis; Richard G. Wilmoth

2005-01-01

346

FORMATION OF A DETACHED PLUME FROM A CEMENT PLANT  

EPA Science Inventory

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

347

40 CFR Appendix Vi to Part 266 - Stack Plume Rise  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Stack Plume Rise VI Appendix VI to Part 266...App. VI Appendix VI to Part 266—Stack Plume Rise [Estimated Plume Rise (in Meters) Based on Stack Exit Flow Rate and Gas Temperature]...

2010-07-01

348

Subsurface Trapping of Multiphase Plumes in Stratification: Laboratory Investigations  

Microsoft Academic Search

Recent observations of subsurface plumes near the Deepwater Horizon Oil Spill have raised many questions about the physics of multiphase plumes in deep ocean environments. Plume evolution and vertical distribution will be a complex function of chemical composition (oil, gas, water, and chemical dispersants), water column density structure, turbulent mixing, and horizontal currents. Here we present early laboratory experiments from

B. L. White; R. Camassa; R. McLaughlin

2010-01-01

349

EXPERIMENTS ON BUOYANT PLUME DISPERSION IN A LABORATORY CONVENTION TANK  

EPA Science Inventory

Buoyant plume dispersion in the convective boundary layer (CBL) is investigated experimentally in a laboratory convection tank. The focus is on highly-buoyant plumes that loft near the CBL capping inversion and resist downward mixing. Highly- buoyant plumes are those with dimen...

350

Mantle plume interaction with an endothermic phase change  

Microsoft Academic Search

High spatial resolution numerical simulations of mantle plumes impinging from below on the endothermic phase change at 660-km depth are used to investigate the effects of latent heat release on the plume-phase change interaction. Both axisymmetric and planar upflows are considered, and the strong temperature dependence of mantle viscosity is taken into account. For plume strengths considered, a Clapeyron slope

Gerald Schubert; Charles Anderson; Peggy Goldman

1995-01-01

351

Preliminary plume characteristics of an arcjet thruster  

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

352

Mantle plumes: Why the current skepticism?  

Microsoft Academic Search

The present reappraisal of the mantle plume hypothesis is perhaps the most exciting current debate in Earth science. Nevertheless, the fundamental reasons for why it has arisen are often not well understood. They are that 1) many observations do not agree with the predictions of the original model, 2) it is possible that convection of the sort required to generate

Gillian R. Foulger

2005-01-01

353

Imaging Fourier transform spectrometry of chemical plumes  

NASA Astrophysics Data System (ADS)

A midwave infrared (MWIR) imaging Fourier transform spectrometer (FTS), the Telops FIRST-MWE (Field-portable Imaging Radiometric Spectrometer Technology - Midwave Extended) has been utilized for the standoff detection and characterization of chemical plumes. Successful collection and analysis of MWIR hyperspectral imagery of jet engine exhaust has allowed us to produce spatial profiles of both temperature and chemical constituent concentrations of exhaust plumes. Successful characterization of this high temperature combustion event has led to the collection and analysis of hyperspectral imagery of lower temperature emissions from industrial smokestacks. This paper presents MWIR data from remote collection of hyperspectral imagery of methyl salicilate (MeS), a chemical warfare agent simulant, during the Chemical Biological Distributed Early Warning System (CBDEWS) test at Dugway Proving Grounds, UT in 2008. The data did not contain spectral lines associated with emission of MeS. However, a few broad spectral features were present in the background-subtracted plume spectra. Further analysis will be required to assign these features, and determine the utility of MWIR hyperspectral imagery for analysis of chemical warfare agent plumes.

Bradley, Kenneth C.; Gross, Kevin C.; Perram, Glen P.

2009-05-01

354

Modeling of Plume Dynamics in Laser Ablation  

Microsoft Academic Search

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

Diomar Lobao; Alex Povitsky

2003-01-01

355

STATISTICAL CHARACTERISTICS OF TURBULENT CHEMICAL PLUMES  

E-print Network

STATISTICAL CHARACTERISTICS OF TURBULENT CHEMICAL PLUMES A Thesis presented to The Academic Faculty for their constant help and motivation during the past one year. Special acknowledgement goes to Shikha Rahman-logarithmic scale. 57 5.10 Typical instantaneous concentration profile along the centerline. 58 5.11 Average

356

PLUME DEFINITION IN REGIONS OF STRONG BENDING  

EPA Science Inventory

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

357

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

NASA Technical Reports Server (NTRS)

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

Doughty, J. O.

1976-01-01

358

Migration and natural fate of a coal tar creosote plume. 1. Overview and plume development  

NASA Astrophysics Data System (ADS)

A volume of sand containing coal tar creosote was emplaced below the water table at CFB Borden to investigate natural attenuation processes for complex biodegradable mixtures. Coal tar creosote is a mixture of more than 200 polycyclic aromatic hydrocarbons, heterocyclic compounds and phenolic compounds. A representative group of seven compounds was selected for detailed study: phenol, m-xylene, naphthalene, phenanthrene, 1-methylnaphthalene, dibenzofuran and carbazole. Movement of groundwater through the source led to the development of a dissolved organic plume, which was studied over a 4-year period. Qualitative plume observations and mass balance calculations indicated two key conclusions: (1) compounds from the same source can display distinctly different patterns of plume development and (2) mass transformation was a major influence on plume behaviour for all observed compounds.

King, Mark W. G.; Barker, James F.

1999-10-01

359

Glycol Ethers As Groundwater Contaminants  

NASA Astrophysics Data System (ADS)

Ether derivatives of dihydroxy alcohols, which are formed from ethylene or propylene, comprise an important group of groundwater contaminants known as glycol ethers. Compounds in this group are used as solvents, cleaning agents, and emulsifiers in many chemical products and manufacturing operations. Glycol ethers have been associated with a variety of toxic effects, and some compounds in the group are relatively potent teratogens. The limited information available suggests that glycol ethers are contaminants in groundwater, especially in anaerobic plumes emanating from disposal of mixed industrial and household waste. Most methods used to analyze groundwater samples cannot adequately detect ?g/? (ppb) concentrations of glycol ethers, and the existing methods perform worst for the most widely used and toxic species. A new method capable of analyzing ?g/? concentrations of glycol ethers was recently developed, and its use is recommended for groundwater samples where glycol ethers are likely to be present.

Ross, Benjamin; Johannson, Gunnar; Foster, Gregory D.; Eckel, William P.

1992-01-01

360

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

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

361

The thin hot plume beneath Iceland  

NASA Astrophysics Data System (ADS)

We present the results of a seismological investigation of the frequency-dependent amplitude variations across Iceland using data from the HOTSPOT array currently deployed there. The array is composed of 30 broad-band PASSCAL instruments. We use the parameter t*, defined in the usual manner from spectral ratios (Halderman & Davis 1991), to compare observed S-wave amplitude variations with those predicted due to both anelastic attenuation and diffraction effects. Four teleseismic events at a range of azimuths are used to measure t*. A 2-D vertical cylindrical plume model with a Gaussian-shaped velocity anomaly is used to model the variations. That part of t* caused by attenuation was estimated by tracing a ray through IASP91, then superimposing our plume model velocity anomaly and calculating the path integral of 1/vQ. That part of t* caused by diffraction was estimated using a 2-D finite difference code to generate synthetic seismograms. The same spectral ratio technique used for the data was then used to extract a predicted t*. The t* variations caused by anelastic attenuation are unable to account for the variations we observe, but those caused by diffraction do. We calculate the t* variations caused by diffraction for different plume models and obtain our best-fit plume, which exhibits good agreement between the observed and measured t*. The best-fit plume model has a maximum S-velocity anomaly of - 12 per cent and falls to 1/e of its maximum at 100 km from the plume centre. This is narrower than previous estimates from seismic tomography, which are broadened and damped by the methods of tomography. This velocity model would suggest greater ray theoretical traveltime delays than observed. However, we find that for such a plume, wave-front healing effects at frequencies of 0.03-0.175 Hz (the frequency range used to pick S-wave arrivals) causes a 40 per cent reduction in traveltime delay, reducing the ray theoretical delay to that observed.

Allen, Richard M.; Nolet, Guust; Morgan, W. Jason; Vogfjörd, Kristín; Bergsson, Bergur H.; Erlendsson, Pálmi; Foulger, G. R.; Jakobsdóttir, Steinunn; Julian, Bruce R.; Pritchard, Matt; Ragnarsson, Sturla; Stefánsson, Ragnar

1999-04-01

362

Population delineation of polar bears using satellite collar data  

USGS Publications Warehouse

To produce reliable estimates of the size or vital rates of a given population, it is important that the boundaries of the population under study are clearly defined. This is particularly critical for large, migratory animals where levels of sustainable harvest are based on these estimates, and where small errors may have serious long-term consequences for the population. Once populations are delineated, rates of exchange between adjacent populations can be determined and accounted/corrected for when calculating abundance (e.g., based on mark-recapture data). Using satellite radio-collar locations for polar bears in the western Canadian Arctic, we illustrate one approach to delineating wildlife populations that integrates cluster analysis methods for determining group membership with home range plotting procedures to define spatial utilization. This approach is flexible with respect to the specific procedures used and provides an objective and quantitative basis for defining population boundaries.

Bethke, R.; Taylor, M.; Amstrup, S.; Messler, F.

1996-01-01

363

Interaction of mantle plumes and migrating mid-ocean ridges: Implications for the Galápagos plume-ridge system  

Microsoft Academic Search

We investigate the three-dimensional interaction of mantle plumes and migrating mid-ocean ridges with variable viscosity numerical models. Numerical models predict that along-axis plume width W and maximum distance of plume-ridge interaction xmax scale with (Q\\/U)1\\/2, where Q is plume source volume flux and U is ridge full spreading rate. Both W and xmax increase with buoyancy number Pib which reflects

Garrett Ito; Jian Lin; Carl W. Gable

1997-01-01

364

Non-intrusive characterization of the redox potential of landfill leachate plumes from self-potential data  

NASA Astrophysics Data System (ADS)

Contaminant plumes (e.g., associated with leakages from municipal landfills) provide a source of natural electrical potentials (or "self-potentials") recordable at the Earth's surface. One contribution to these self-potentials is associated with pore water flow (i.e., the "streaming potential"), and the other is related to redox conditions. A contaminant plume can be regarded as a "geobattery": the source current potentially results from the degradation of the organic matter by micro-organisms, which produces electrons. These electrons are then carried by nanowires that connect bacteria and thorough metallic particles that precipitate in areas of strong redox potential gradient. In the case of the Entressen landfill (South of France), reported here, the hydraulic head differences measured in piezometers outside the contaminant plume is strongly linked to the surface self-potential signals, with a correlation coefficient of - 0.94. We used a Bayesian method that combines hydraulic head and self-potential data collected outside the contaminated area to estimate the streaming potential component of the collected self-potential data. Once the streaming potential contribution was removed from the measured self-potentials, the correlation coefficient between the residual self-potentials and the measured redox potentials in the aquifer was 0.92. The slope of this regression curve was close to 0.5, which was fairly consistent with both finite element modelling and the proposed geobattery model.

Arora, T.; Linde, N.; Revil, A.; Castermant, J.

2007-07-01

365

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

SciTech Connect

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

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

2005-02-24

366

Irreversible phosphorus sorption in septic system plumes?  

PubMed

The mobility of phosphorus (P) in septic system plumes remains a topic of debate because of the considerable reactivity of this constituent. In this study, a septic system plume in Ontario was monitored over a 16-year period with detail that clearly shows the advancing frontal portion of the P plume. This monitoring record provides insight into the extent of secondary P attenuation in the ground water zone beyond that available from previous studies. A P plume 16 m in length developed over the monitoring period with PO(4)-P concentrations (3 to 6 mg/L) that approached the concentrations present under the tile bed. Simulations using an analytical model showed that when first-order solute decay was considered to account for the possibility of secondary P attenuation in the ground water zone, field values could only be matched when decay was absent or occurred at an exceedingly slow rate (half-life greater than 30 years). Thus, hypothesized secondary P attenuation mechanisms such as slow recystallization of sorbed P into insoluble metal phosphate minerals, diffusion into microsites, or kinetically slow direct precipitation of P minerals such as hydroxyapatite were inactive in the ground water zone at this site or occurred at rates that were too slow to be observed in the context of the current 16-year study. Desorption tests on sediment samples from below the tile bed indicated a PO(4) distribution coefficient (K(d)) of 4.8, which implies a P retardation factor of 25, similar to the field apparent value of 37 determined from model calibrations. This example of inactive secondary P attenuation in the ground water zone shows that phosphorus in some ground water plumes can remain mobile and conservative for decades. This has important implications for septic systems located in lakeshore environments when long-term usage scenarios are considered. PMID:18181864

Robertson, W D

2008-01-01

367

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

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

368

Shuttle active thermal control system development testing. Volume 6: Water ejector plume tests  

NASA Technical Reports Server (NTRS)

Results are given of vacuum testing of nozzles designed to eject water vapor away from the space shuttle to prevent contamination of the spacecraft surfaces and payload. The water vapor is generated by an active cooling system which evaporates excess fuel cell water to supplement a modular radiator system (MRS). The complete heat rejection system including the MRS, flash evaporator or sublimator and nozzle were first tested to demonstrate the system operational characteristics. The plume tests were performed in two phases and the objectives of this test series were: (1) to determine the effectiveness of a supersonic nozzle and a plugged nozzle in minimizing impingement upon the spacecraft of water vapor exhausted by an active device (flash evaporator or sublimator); and (2) to obtain basic data on the flow fields of exhaust plumes generated by these active devices, both with and without nozzles installed.

Mcginnis, F. K.; Summerhays, R. M.

1973-01-01

369

Phenotypic and Genetic Structure of Traits Delineating Personality Disorder  

Microsoft Academic Search

Background: The evidence suggests that personality traits are hierarchically organized with more specific or lower-order traits combining to form more generalized higher-order traits. Agreement exists across studies re- garding the lower-order traits that delineate personality disorder but not the higher-order traits. This study seeks to identify the higher-order structure of personality dis- order by examining the phenotypic and genetic struc-

W. John Livesley; Kerry L. Jang; Philip A. Vernon

1998-01-01

370

SRNL EMERGENCY RESPONSE CAPABILITY FOR ATMOSPHERIC CONTAMINANT RELEASES  

SciTech Connect

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

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

2006-07-12

371

Denitrification in a BTEX Contaminated Aquifer Containing Reduced Sulfur  

Microsoft Academic Search

At a former gasworks plant in Duesseldorf (Germany) a massive soil and groundwater contamination with BTEX (up to 100 mg\\/l) and to a minor extent with PAH (up to 10 mg\\/l) were detected. Mainly due to sulfate and iron-(III) reduction, a natural biodegradation has occurred and restricted the length of the contaminant plume in the direction of groundwater flow to

P. Eckert; C. Appelo; F. Wisotzky; P. Obermann

2001-01-01

372

Methods for Data-based Delineation of Spatial Regions  

SciTech Connect

In data analysis, it is often useful to delineate or segregate areas of interest from the general population of data in order to concentrate further analysis efforts on smaller areas. Three methods are presented here for automatically generating polygons around spatial data of interest. Each method addresses a distinct data type. These methods were developed for and implemented in the sample planning tool called Visual Sample Plan (VSP). Method A is used to delineate areas of elevated values in a rectangular grid of data (raster). The data used for this method are spatially related. Although VSP uses data from a kriging process for this method, it will work for any type of data that is spatially coherent and appears on a regular grid. Method B is used to surround areas of interest characterized by individual data points that are congregated within a certain distance of each other. Areas where data are “clumped” together spatially will be delineated. Method C is used to recreate the original boundary in a raster of data that separated data values from non-values. This is useful when a rectangular raster of data contains non-values (missing data) that indicate they were outside of some original boundary. If the original boundary is not delivered with the raster, this method will approximate the original boundary.

Wilson, John E.

2012-10-01

373

Optimizing Pumping Strategies for Contaminant Studies and Remedial Actions.  

National Technical Information Service (NTIS)

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

J. F. Keely

1984-01-01

374

OPTIMIZING PUMPING STRATEGIES FOR CONTAMINANT STUDIES AND REMEDIAL ACTIONS  

EPA Science Inventory

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

375

Can optical remote sensing techniques detect air contaminants?  

Microsoft Academic Search

The American Petroleum Institute (API) is sponsoring a program to evaluate if and how optical remote sensing techniques can be used to detect air contaminant emissions at a processing facility. This study is also gathering database information to assess whether dispersion modeling accurately depicts air plume migrations within a petrochemical site. In early 1995, an initial field study was conducted

R. J. Paine; J. O. Zwicker; H. J. Feldman

1998-01-01

376

Phytoremediation of Nitrate-Contaminated Groundwater by Desert Phreatophytes  

Microsoft Academic Search

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

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

377

Fallout plume of submerged oil from Deepwater Horizon  

PubMed Central

The sinking of the Deepwater Horizon in the Gulf of Mexico led to uncontrolled emission of oil to the ocean, with an official government estimate of ?5.0 million barrels released. Among the pressing uncertainties surrounding this event is the fate of ?2 million barrels of submerged oil thought to have been trapped in deep-ocean intrusion layers at depths of ?1,000–1,300 m. Here we use chemical distributions of hydrocarbons in >3,000 sediment samples from 534 locations to describe a footprint of oil deposited on the deep-ocean floor. Using a recalcitrant biomarker of crude oil, 17?(H),21?(H)-hopane (hopane), we have identified a 3,200-km2 region around the Macondo Well contaminated by ?1.8 ± 1.0 × 106 g of excess hopane. Based on spatial, chemical, oceanographic, and mass balance considerations, we calculate that this contamination represents 4–31% of the oil sequestered in the deep ocean. The pattern of contamination points to deep-ocean intrusion layers as the source and is most consistent with dual modes of deposition: a “bathtub ring” formed from an oil-rich layer of water impinging laterally upon the continental slope (at a depth of ?900–1,300 m) and a higher-flux “fallout plume” where suspended oil particles sank to underlying sediment (at a depth of ?1,300–1,700 m). We also suggest that a significant quantity of oil was deposited on the ocean floor outside this area but so far has evaded detection because of its heterogeneous spatial distribution. PMID:25349409

Valentine, David L.; Fisher, G. Burch; Bagby, Sarah C.; Nelson, Robert K.; Reddy, Christopher M.; Sylva, Sean P.; Woo, Mary A.

2014-01-01

378

Fallout plume of submerged oil from Deepwater Horizon.  

PubMed

The sinking of the Deepwater Horizon in the Gulf of Mexico led to uncontrolled emission of oil to the ocean, with an official government estimate of ?5.0 million barrels released. Among the pressing uncertainties surrounding this event is the fate of ?2 million barrels of submerged oil thought to have been trapped in deep-ocean intrusion layers at depths of ?1,000-1,300 m. Here we use chemical distributions of hydrocarbons in >3,000 sediment samples from 534 locations to describe a footprint of oil deposited on the deep-ocean floor. Using a recalcitrant biomarker of crude oil, 17?(H),21?(H)-hopane (hopane), we have identified a 3,200-km(2) region around the Macondo Well contaminated by ?1.8 ± 1.0 × 10(6) g of excess hopane. Based on spatial, chemical, oceanographic, and mass balance considerations, we calculate that this contamination represents 4-31% of the oil sequestered in the deep ocean. The pattern of contamination points to deep-ocean intrusion layers as the source and is most consistent with dual modes of deposition: a "bathtub ring" formed from an oil-rich layer of water impinging laterally upon the continental slope (at a depth of ?900-1,300 m) and a higher-flux "fallout plume" where suspended oil particles sank to underlying sediment (at a depth of ?1,300-1,700 m). We also suggest that a significant quantity of oil was deposited on the ocean floor outside this area but so far has evaded detection because of its heterogeneous spatial distribution. PMID:25349409

Valentine, David L; Fisher, G Burch; Bagby, Sarah C; Nelson, Robert K; Reddy, Christopher M; Sylva, Sean P; Woo, Mary A

2014-11-11

379

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

EPA Science Inventory

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

380

Z .Journal of Contaminant Hydrology 51 2001 145161 www.elsevier.comrlocaterjconhyd  

E-print Network

plume at a uranium mill tailings site in western USA. Numerous ground water geochemistry data for accurate prediction of contaminant fate and transport. q 2001 Elsevier Science B.V. All rights reserved. Keywords: Mineralogy; Contaminant transport; Uranium; Acid mine drainage; Modeling ) Corresponding author

Polly, David

381

Roles of back diffusion and biodegradation reactions in sustaining MTBE/TBA plumes in alluvial media  

NASA Astrophysics Data System (ADS)

A plume of methyl tert-butyl ether (MTBE) and tert-butyl alcohol (TBA) originating from a gasoline spill in late 1994 at Vandenberg Air Force Base (VAFB) persisted above regulatory concentration goals for over 15 years within 200 feet of the original spill source. The plume persisted until 2010 despite excavation of the tanks and piping within months after the spill and excavations of additional contaminated sediments from the source area in 2007 and 2008. Two-dimensional reactive transport simulations of MTBE and TBA along the plume centerline were conducted for a 20-year period following the spill. As previously reported by Rasa et al. (2011), these analyses suggest that MTBE diffused from the thin anaerobic aquifer into the adjacent anaerobic silts and transformed to TBA in both aquifer and silt layers. After 2004, TBA was the dominant solute, diffusing back out of the silts into the aquifer and sustaining plume concentrations. Simulations also suggest that aerobic degradation of MTBE or TBA at the water table in the overlying silt layer significantly reduced the time for MTBE and TBA concentrations to reach regulatory goals by limiting the chemical mass available for back diffusion to the aquifer. We have extended that prior work; using the same reaction and diffusion parameters, we explored the sensitivity of the results to thicknesses of the alluvial layers in order to determine under what sets of conditions a reaction zone accessed only by vertical diffusion through a silt from an underlying contaminated aquifer can significantly affect time to achievement of compliance goals within the aquifer.

Mackay, D. M.; Rasa, E.

2011-12-01

382

Experimental visualization and modeling of biodegradation at the plume fringe gradient  

NASA Astrophysics Data System (ADS)

Biodegradation of organic contaminants via consumption of electron acceptors happens often at the fringe of contaminant plumes in groundwater. The dispersive mixing at the biogeochemical gradient there has an important influence on the degradation that is limited by the supply of electron acceptors and the maximum utilization rate of the microbial population present at the gradient. We have performed two-dimensional laboratory experiments to study this situation non-invasively in detail. Reactive experiments with acetate and phenol as contaminant are compared to non-reactive experiments. The numerical modelling has not only to take care of the actual processes but also handle numerical dispersion, e.g. to avoid artificially high degradation rates. The study aims for identifying the correct conceptual approach to describe the biodegradation at the gradient most accurately. Since dispersion and biodegradation may not act independently from each other, another experimental approach via Nuclear Magnetic Resonance imaging is proposed to explore this potential coupling at the pore scale.

Oswald, S. E.; Banwart, S. A.; Rees, H. C.

2005-12-01

383

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

NASA Astrophysics Data System (ADS)

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

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

2011-11-01

384

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

USGS Publications Warehouse

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

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

2011-01-01

385

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

SciTech Connect

Metals contamination exceeding drinking water standards (MCLs) is associated with acidic leachate generated from a coal pile runoff basin at the Savannah River Site (SRS) in Aiken, South Carolina. The metals plume extends over 100 acres with its' distal boundary about onehalf mile from the Savannah River. Based on the large plume extent and high dissolved iron and aluminum concentrations, conventional treatment technologies are likely to be ineffective and cost prohibitive. In-situ bioremediation using existing groundwater microbes is being evaluated as a promising alternative technology for effective treatment, along with consideration of natural attenuation of the lower concentration portions of the plume to meet remedial goals. Treatment of the high concentration portion of the groundwater plume by sulfate-reducing bacteria (SRB) is being evaluated through laboratory microcosm testing and a field-scale demonstration. Organic substrates are added to promote SRB growth. These bacteria use dissolved sulfate as an electron acceptor and ultimately precipitate dissolved metals as metal sulfides. Laboratory microcosm testing indicate SRB are present in groundwater despite low pH conditions, and that their growth can be stimulated by soybean oil and sodium lactate. The field demonstration consists of substrate injection into a 30-foot deep by 240-foot long permeable trench. Microbial activity is demonstrated by an increase in pH from 3 to 6 within the trench. Downgradient monitoring will be used to evaluate the effectiveness of SRB in reducing metal concentrations. Natural attenuation (NA) is being evaluated for the low concentration portion of the plume. A decrease in metal mobility can occur through a variety of abiotically and/or biotically mediated mechanisms. Quantification of these mechanisms is necessary to more accurately predict contaminant attenuation using groundwater transport models that have historically relied on simplified conservative assumptions. Result s from matched soil/porewater samples indicate higher soil/water partition coefficients (Kds) with increasing distance from the source. In addition, site-specific metals availability is being assessed using sequential extraction techniques, which more accurately represent environmental conditions as compared to default EPA extraction methods. Due to elevated sulfate levels in the plume, SRB are most likely to be the dominant biotic contributor to NA processes.

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

2003-02-27

386

Characterization of DNAPL Source Zone Architecture and Prediction of Associated Plume Response: Progress and Perspectives  

NASA Astrophysics Data System (ADS)

It is now widely recognized that the distribution of contaminant mass will control both the evolution of aqueous phase plumes and the effectiveness of many source zone remediation technologies at sites contaminated by dense nonaqueous phase liquids (DNAPLs). Advances in the management of sites containing DNAPL source zones, however, are currently hampered by the difficulty associated with characterizing subsurface DNAPL 'architecture'. This presentation provides an overview of recent research, integrating experimental and mathematical modeling studies, designed to improve our ability to characterize DNAPL distributions and predict associated plume response. Here emphasis is placed on estimation of the most information-rich DNAPL architecture metrics, through a combination of localized in situ tests and more readily available plume transect concentration observations. Estimated metrics will then serve as inputs to an upscaled screening model for prediction of long term plume response. Machine learning techniques were developed and refined to identify a variety of source zone metrics and associated confidence intervals through the processing of down gradient concentration data. Estimated metrics include the volumes and volume percentages of DNAPL in pools and ganglia, as well as their ratio (pool fraction). Multiphase flow and transport simulations provided training data for model development and assessment that are representative of field-scale DNAPL source zones and their evolving plumes. Here, a variety of release and site heterogeneity (sequential Gaussian permeability) conditions were investigated. Push-pull tracer tests were also explored as a means to provide localized in situ observations to refine these metric estimates. Here, two-dimensional aquifer cell experiments and mathematical modeling were used to quantify upscaled interphase mass transfer rates and the interplay between injection and extraction rates, local source zone architecture, and tracer concentration measurements. Finally, two-dimensional aquifer cell experiments for representative DNAPL release events were performed to explore the link between source zone metrics and plume development, and to demonstrate the utility of the developed estimation tools and upscaled models. Research results reveal that, for the subsurface scenarios examined, many metrics can be estimated at greater than 80% accuracy from concentration transect measurements. Partitioning tracer investigations demonstrate that push-pull tracer data cannot be accurately modeled using local equilibrium assumptions and that fitted upscaled mass transfer coefficients exhibit a strong dependence on DNAPL mass distribution, a dependence that can be exploited for local metric identification. Aquifer cell experiments demonstrate that upscaled screening model predictions can capture the multi-stage behavior of single component NAPL fluxes from source zone architectures initially characterized as ganglia-dominated, and that transitions from ganglia- to pool-dominated architecture can be predicted using source zone metrics such as pool fraction.

Abriola, L. M.; Pennell, K. D.; Ramsburg, C. A.; Miller, E. L.; Christ, J.; Capiro, N. L.; Mendoza-Sanchez, I.; Boroumand, A.; Ervin, R. E.; Walker, D. I.; Zhang, H.

2012-12-01

387

Design, Fabrication, and Testing of Emissive Probes to Determine the Plasma Potential of the Plumes of Various Electric Thrusters  

NASA Technical Reports Server (NTRS)

A significant problem in the use of electric thrusters in spacecraft is the formation of low-energy ions in the thruster plume. Low-energy ions are formed in the plume via random collisions between high-velocity ions ejected from the thruster and slow-moving neutral atoms of propellant effusing from the engine. The sputtering of spacecraft materials due to interactions with low-energy ions may result in erosion or contamination of the spacecraft. The trajectory of these ions is determined primarily by the plasma potential of the plume. Thus, accurate characterization of the plasma potential is essential to predicting low-energy ion contamination. Emissive probes were utilized to determine the plasma potential. When the ion and electron currents to the probe are balanced, the potential of such probes float to the plasma potential. Two emissive probes were fabricated; one utilizing a DC power supply, another utilizing a rectified AC power source. Labview programs were written to coordinate and automate probe motion in the thruster plume. Employing handshaking interaction, these motion programs were synchronized to various data acquisition programs to ensure precision and accuracy of the measurements. Comparing these experimental values to values from theoretical models will allow for a more accurate prediction of low-energy ion interaction.

Chen, Erinna M.

2005-01-01

388

Summertime Changjiang River plume variation during 1998-2010  

NASA Astrophysics Data System (ADS)

an improved satellite-derived salinity algorithm in the East China Sea (ECS), we presented and examined a general view on summertime Changjiang River plume variation during 1998-2010. Three types of plume shapes were identified: (1) the commonly known northeastward transportation, (2) a case in which most of the plume water crossed the Cheju Strait into the Tsushima-Korea Straits with only a small fraction staying on the shelf of the ECS, and (3) a rare case in which the plume front moved southeastward. Satellite time-series data suggested that, during the peak river discharge time in July with favorable southwest monsoon, the plume area was highly correlated with the river discharge of the same month. Interestingly, the plume area in August was also dominated by the discharge in July. In August, as the direct effect of freshwater discharge weakening, the plume area also became positively correlated with wind speed in the 45° and 60°direction, suggesting that the plume extension was more influenced by the southwesterly wind during periods of smaller discharge. Furthermore, a few special cases with unique plume extensions were found under extreme weather conditions. Finally, we found no significant long-term trend of plume area change over 1998-2010 in summertime and concluded that the interannual variation was probably regulated by natural variation rather than anthropogenic effects, such as construction of the Three Gorges Dam. This study will have implications for biogeochemical and modeling studies in large river plume areas.

Bai, Yan; He, Xianqiang; Pan, Delu; Chen, Chen-Tung Arthur; Kang, Yan; Chen, Xiaoyan; Cai, Wei-Jun

2014-09-01

389

Groundwater Contamination  

NSDL National Science Digital Library

This investigation consists of two parts, in which students first model the effects of groundwater contamination and then track the flow of the contamination. However, Part I does not have to be done in order to do Part II. This Teacher Information sectio

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

2009-04-01

390

The reactive bed plasma system for contamination control  

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

391

On possible plume-guided seismic waves  

USGS Publications Warehouse

Hypothetical thermal plumes in the Earth's mantle are expected to have low seismic-wave speeds and thus would support the propagation of guided elastic waves analogous to fault-zone guided seismic waves, fiber-optic waves, and acoustic waves in the oceanic SOund Fixing And Ranging channel. Plume-guided waves would be insensitive to geometric complexities in the wave guide, and their dispersion would make them distinctive on seismograms and would provide information about wave-guide structure that would complement seismic tomography. Detecting such waves would constitute strong evidence of a new kind for the existence of plumes. A cylindrical channel embedded in an infinite medium supports two classes of axially symmetric elastic-wave modes, torsional and longitudinal-radial. Torsional modes have rectilinear particle motion tangent to the cylinder surface. Longitudinal-radial modes have elliptical particle motion in planes that include the cylinder axis, with retrograde motion near the axis. The direction of elliptical particle motion reverses with distance from the axis: once for the fundamental mode, twice for the first overtone, and so on. Each mode exists only above its cut-off frequency, where the phase and group speeds equal the shear-wave speed in the infinite medium. At high frequencies, both speeds approach the shear-wave speed in the channel. All modes have minima in their group speeds, which produce Airy phases on seismograms. For shear wave-speed contrasts of a few percent, thought to be realistic for thermal plumes in the Earth, the largest signals are inversely dispersed and have dominant frequencies of about 0.1-1 Hz and durations of 15-30 sec. There are at least two possible sources of observable plume waves: (1) the intersection of mantle plumes with high-amplitude core-phase caustics in the deep mantle; and (2) ScS-like reflection at the core-mantle boundary of downward-propagating guided waves. The widespread recent deployment of broadband seismometers makes searching for these waves possible.

Julian, B. R.; Evans, J. R.

2010-01-01

392

Io Plume Monitoring (frames 1-36)  

NASA Technical Reports Server (NTRS)

A sequence of full disk Io images was taken prior to Galileo's second encounter with Ganymede. The purpose of these observations was to view all longitudes of Io and search for active volcanic plumes. The images were taken at intervals of approximately one hour corresponding to Io longitude increments of about ten degrees. Because both the spacecraft and Io were traveling around Jupiter the lighting conditions on Io (e.g. the phase of Io) changed dramatically during the sequence. These images were registered at a common scale and processed to produce a time-lapse 'movie' of Io. This movie combines all of the plume monitoring frames obtained by the Solid State Imaging system aboard NASA's Galileo spacecraft.

The most prominent volcanic plume seen in this movie is Prometheus (latitude 1.6 south, longitude 153 west). The plume becomes visible as it moves into daylight, crosses the center of the disk, and is seen in profile against the dark of space at the edge of Io. This plume was first seen by the Voyager 1 spacecraft in 1979 and is believed to be a geyser-like eruption of sulfur dioxide snow and gas. Although details of the region around Prometheus have changed in the seventeen years since Voyager's visit, the shape and height of the plume have not changed significantly. It is possible that this geyser has been erupting nearly continuously over this time. Galileo's primary 24 month mission includes eleven orbits around Jupiter and will provide observations of Jupiter, its moons and its magnetosphere.

North is to the top of all frames. The smallest features which can be discerned range from 13 to 31 kilometers across. The images were obtained between the 2nd and the 6th of September, 1996.

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 Techno