ENVIRONMENTAL RESEARCH BRIEF: USE OF CATIONIC SURFACTANTS TO MODIFY AQUIFER MATERIALS TO REDUCE THE MOBILITY OF HYDROPHOBIC ORGANIC COMPOUNDS

EPA Science Inventory

Cationic surfactants can be used to modify surfaces of soils and subsurface materials to promote sorption of hydrophobic organic compounds (HOC) and retard their migration. For example, cationic surfactants could be injected into an aquifer downgradient from a source of HOC conta...

Predicting hydrology in wetlands designed for coastal stormwater management

Treesearch

William H. Strosnider; Daniel R. Hitchcock; Alan J. Lewitus

2007-01-01

Detention ponds are currently accepted as stormwater best management practices (BMPs) in coastal South Carolina. These ponds are typical catch basins for stormwater piped directly from impervious surfaces in many residential and resort areas. Nutrients often concentrate in the ponds and contribute to eutrophication within the ponds and downgradient estuaries. A...

40 CFR 257.5 - Disposal standards for owners/operators of non-municipal non-hazardous waste disposal units that...

Code of Federal Regulations, 2010 CFR

2010-07-01

... compliance with §§ 257.7 through 257.30 prior to the receipt of CESQG hazardous waste. (b) Definitions.... Waste management unit boundary means a vertical surface located at the hydraulically downgradient limit.../operators of non-municipal non-hazardous waste disposal units that receive Conditionally Exempt Small...

Arsenic transport between surface and groundwater in a moderately reducing zone: Geochemical approach

NASA Astrophysics Data System (ADS)

Khaska, Mahmoud; Le Gal La Salle, Corinne; Verdoux, Patrick

2015-04-01

Arsenic contamination represents a major risk to human health as one of the most prominent environmental causes of cancer mortality. Mining activities, particularly those involving arsenic rich ores have an impact on the environment and on human health that may persist for many decades after mine closure. The relationships between As released from alluvial aquifer in the vicinity of the sulfide-rich mine dumps was demonstrated with geochemical and isotopic tracers (major and traces elements, 87Sr/86Sr, 18O, 2H). Strontium isotopes were used to trace the transport of As downstream from a As rich tailing dam. Increasing As and Fe concentrations in surface water are explained by As release associated with alluvial groundwater discharge to the stream. This process occurs in a moderately reduced section of the stream downgradient from the sulfide-rich tailing dam. High As, total Fe and low Eh in groundwater confirm the discharge of alluvial groundwater and explain its impact on surface water. Transport of As between surface and groundwater can be described as follows: 1- Subsurface moderately reducing conditions prevail in groundwater downgradient from the tailing dams. This suggests a flux of reduced water from sulfide-rich tailing dams which is characterized by its high As and Fe content resulting from the reduction of Fe-sulfides. 2- Upon mixing with surface water, oxidizing conditions prevails and precipitate as Fe hydroxide on the stream bed. As and Sr subsequently adsorbed on the Fe -oxyhydroxide surface. This process contributes to the immobilization of As in surface water. Remaining dissolved As in surface water can be re-introduced in alluvial groundwater downstream of the reducing zone.

Momentum and buoyancy transfer in atmospheric turbulent boundary layer over wavy water surface - Part 1: Harmonic wave

NASA Astrophysics Data System (ADS)

Troitskaya, Yu. I.; Ezhova, E. V.; Zilitinkevich, S. S.

2013-10-01

The surface-drag and mass-transfer coefficients are determined within a self-consistent problem of wave-induced perturbations and mean fields of velocity and density in the air, using a quasi-linear model based on the Reynolds equations with down-gradient turbulence closure. Investigation of a harmonic wave propagating along the wind has disclosed that the surface drag is generally larger for shorter waves. This effect is more pronounced in the unstable and neutral stratification. The stable stratification suppresses turbulence, which leads to weakening of the momentum and mass transfer.

Postconstruction report of the United Nuclear Corporation Disposal Site at the Oak Ridge Y-12 Plant, Oak Ridge, Tennessee. Environmental Restoration Program

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oakley, L.B.; Siberell, J.K.; Voskuil, T.L.

1993-06-01

Remedial actions conducted under the auspices of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) were completed at the Y-12 United Nuclear Corporation (UNC) Disposal Site in August 1992. The purpose of this Postconstruction Report is to summarize numerous technical reports and provide CERCLA documentation for completion of the remedial actions. Other CERCLA reports, such as the Feasibility Study for the UNC Disposal Site, provide documentation leading up to the remedial action decision. The remedial action chosen, placement of a modified RCRA cap, was completed successfully, and performance standards were either met or exceeded. This remedial action provided solutionsmore » to two environmentally contaminated areas and achieved the goal of minimizing the potential for contamination of the shallow groundwater downgradient of the site, thereby providing protection of human health and the environment. Surveillance and maintenance of the cap will be accomplished to ensure cap integrity, and groundwater monitoring downgradient of the site will continue to confirm the acceptability of the remedial action chosen.« less

Data Validation Package October 2015 Groundwater and Surface Water Sampling at the Monticello, Utah, Processing Site January 2016

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen, Jason; Smith, Fred

Sampling Period: October 12–14, 2015. This semiannual event includes sampling groundwater and surface water at the Monticello Mill Tailings Site. Sampling and analyses were conducted as specified in the 2004 Monticello Mill Tailings Site Operable Unit III Post-Record of Decision Monitoring Plan, Draft Final and Sampling and Analysis Plan for U.S. Department of Energy Office of Legacy Management Sites (LMS/PRO/S04351, continually updated). Samples were collected from 52 of 61 planned locations (15 of 17 former mill site wells, 17 of 18 downgradient wells, 9 of 9 downgradient permeable reactive barrier wells, 2 of 7 seeps and wetlands, and 9 ofmore » 10 surface water locations). Locations MW00-07, Seep 1, Seep 2, Seep 3, Seep 5, Seep 6, SW00-01, T01-13, and T01-19 were not sampled because of insufficient water availability. All samples were filtered as specified in the monitoring plan. Duplicate samples were collected from surface water location W3-04 and from monitoring wells 82-08, 92-09, and 92-10. Water levels were measured at all but one sampled well and an additional set of wells. The contaminants of concern (COCs) for the Monticello Mill Tailings Site are arsenic, manganese, molybdenum, nitrate + nitrite as nitrogen (nitrate + nitrite as N), selenium, uranium, and vanadium. Time-concentration graphs of the COCs for all groundwater and surface water locations are included in this report. Locations with COCs that exceeded remediation goals are listed.« less

Simulation of ground-water flow in the St. Peter aquifer in an area contaminated by coal-tar derivatives, St. Louis Park, Minnesota. Water Resources Investigation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lorenz, D.L.; Stark, J.R.

1990-01-01

A model constructed to simulate ground-water flow in part of the Prairie du Chien-Jordan and St. Peter aquifers, St. Louis Park, Minnesota, was used to test hypotheses about the movement of ground water contaminated with coal-tar derivatives and to simulate alternatives for reducing the downgradient movement of contamination in the St. Peter aquifer. The model, constructed for a previous study, was applied to simulate the effects of current ground-water withdrawals on the potentiometric surface of the St. Peter aquifer. Model simulations predict that the multiaquifer wells have the potential to limit downgradient migration of contaminants in the St. Peter aquifermore » caused by cones of depression created around the multiaquifer wells. Differences in vertical leakage to the St. Peter aquifer may exist in areas of bedrock valleys. Model simulations indicate that these differences are not likely to affect significantly the general patterns of ground-water flow.« less

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

USGS Publications Warehouse

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

1992-01-01

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.

Data Validation Package April 2016 Groundwater and Surface Water Sampling at the Monticello, Utah, Disposal and Processing Sites August 2016

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen, Jason; Smith, Fred

This semiannual event includes sampling groundwater and surface water at the Monticello Disposal and Processing Sites. Sampling and analyses were conducted as specified in the Sampling and Analysis Plan for U.S. Department of Energy Office of Legacy Management Sites (LMS/PRO/S04351, continually updated) and Program Directive MNT-2016-01. Complete sample sets were collected from 42 of 48 planned locations (9 of 9 former mill site wells, 13 of 13 downgradient wells, 7 of 9 downgradient permeable reactive barrier wells, 4 of 7 seeps and wetlands, and 9 of 10 surface water locations). Planned monitoring locations are shown in Attachment 1, Sampling andmore » Analysis Work Order. Locations R6-M3, SW00-01, Seep 1, Seep 2, and Seep 5 were not sampled due to insufficient water availability. A partial sample was collected at location R4-M3 due to insufficient water. All samples from the permeable reactive barrier wells were filtered as specified in the program directive. Duplicate samples were collected from surface water location Sorenson and from monitoring wells 92-07 and RlO-Ml. Water levels were measured at all sampled wells and an additional set of wells. See Attachment2, Trip Report for additional details. The contaminants of concern (COCs) for the Monticello sites are arsenic, manganese, molybdenum, nitrate+ nitrite as nitrogen (nitrate+ nitrite as N), selenium, uranium, and vanadium. Locations with COCs that exceeded remediation goals are listed in Table 1 and Table 2. Time-concentration graphs of the COCs for all groundwater and surface water locations are included in Attachment 3, Data Presentation. An assessment of anomalous data is included in Attachment 4.« less

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

USGS Publications Warehouse

Harvey, Ronald W.; Barber, Larry B.

1992-01-01

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.

Spatial and temporal migration of a landfill leachate plume in alluvium

USGS Publications Warehouse

Masoner, Jason R.; Cozzarelli, Isabelle M.

2015-01-01

Leachate from unlined or leaky landfills can create groundwater contaminant plumes that last decades to centuries. Understanding the dynamics of leachate movement in space and time is essential for monitoring, planning and management, and assessment of risk to groundwater and surface-water resources. Over a 23.4-year period (1986–2010), the spatial extent of the Norman Landfill leachate plume increased at a rate of 7800 m2/year and expanded by 878 %, from an area of 20,800 m2 in 1986 to 203,400 m2 in 2010. A linear plume velocity of 40.2 m/year was calculated that compared favorably to a groundwater-seepage velocity of 55.2 m/year. Plume-scale hydraulic conductivity values representative of actual hydrogeological conditions in the alluvium ranged from 7.0 × 10−5 to 7.5 × 10−4 m/s, with a median of 2.0 × 10−4 m/s. Analyses of field-measured and calculated plume-scale hydraulic conductivity distributions indicate that the upper percentiles of field-measured values should be considered to assess rates of plume-scale migration, spreading, and biodegradation. A pattern of increasing Cl− concentrations during dry periods and decreasing Cl− concentrations during wet periods was observed in groundwater beneath the landfill. The opposite occurred in groundwater downgradient from the landfill; that is, Cl− concentrations in groundwater downgradient from the landfill decreased during dry periods and increased during wet periods. This pattern of changing Cl−concentrations in response to wet and dry periods indicates that the landfill retains or absorbs leachate during dry periods and produces lower concentrated leachate downgradient. During wet periods, the landfill receives more recharge which dilutes leachate in the landfill but increases leachate migration from the landfill and produces a more concentrated contaminant plume. This approach of quantifying plume expansion, migration, and concentration during variable hydrologic conditions provides increased understanding of plume behavior and migration potential and may be applied at less monitored landfill sites to evaluate potential risks of contamination to downgradient receptors.

Geochemical Trends and Natural Attenuation of RDX, Nitrate, and Perchlorate in the Hazardous Test Area Fractured-Granite Aquifer, White Sands Missile Range, New Mexico, 1996-2006

USGS Publications Warehouse

Langman, Jeff B.; Robertson, Andrew J.; Bynum, Jamar; Gebhardt, Fredrick E.

2008-01-01

A fractured-granite aquifer at White Sands Missile Range is contaminated with the explosive compound RDX, nitrate, and perchlorate (oxidizer associated with rocket propellant) from the previous use of the Open Burn/Open Detonation site at the Hazardous Test Area. RDX, nitrate, and perchlorate ground-water concentrations were analyzed to examine source characteristics, spatial and temporal variability, and the influence of the natural attenuation processes of dilution and degradation in the Hazardous Test Area fractured-granite aquifer. Two transects of ground-water wells from the existing monitoring-site network - one perpendicular to ground-water flow (transect A-A') and another parallel to ground-water flow (transect B-B') - were selected to examine source characteristics and the spatial and temporal variability of the contaminant concentrations. Ground-water samples collected in 2005 from a larger sampling of monitoring sites than the two transects were analyzed for various tracers including major ions, trace elements, RDX degradates, dissolved gases, water isotopes, nitrate isotopes, and sulfate isotopes to examine the natural attenuation processes of dilution and degradation. Recharge entrains contaminants at the site and transports them downgradient towards the Tularosa Basin floor through a poorly connected fracture system(s). From 1996 to 2006, RDX, nitrate, and perchlorate concentrations in ground water downgradient from the Open Burn/Open Detonation site have been relatively stable. RDX, nitrate, and perchlorate in ground water from wells near the site indicate dispersed contaminant sources in and near the Open Burn/Open Detonation pits. The sources of RDX and nitrate in the pit area have shifted with time, and the shift correlates with the regrading of the south and east berms of each pit in 2002 and 2003 following closure of the site. The largest RDX concentrations were in ground water about 0.1 mile downgradient from the pits, the largest perchlorate concentrations were in ground water about 0.15 mile downgradient from the pits, and the largest nitrate concentrations were in ground water about 0.25 mile down-gradient from the pits. Strong and moderate correlation of water level and the contaminant concentrations near the source areas and low correlation outside and downgradient from the source areas indicates a diminishing of the water level/contaminant relation with downgradient flow. Ground water was not progressively older at all locations downgradient from the Open Burn/Open Detonation site indicating multiple recharge areas. Major ion and strontium concentrations and d2H and d18O values identified similar sources of recharge waters comprising the aquifer except along the basin periphery where recharge water may be influenced by dissolution of mineral assemblages associated with ore deposits that are present along the basin margins. Ground-water ages, dissolved-solids concentrations, and calcium-strontium concentrations indicate limited or partial connectivity between fractures and contributions of uncontaminated recharge water downgradient from the site that dilutes contaminant concentrations. Changes in RDX and nitrate concentration patterns, the presence of methane, changes in carbon dioxide concentrations and d15N and d34S values, and variable reduction-oxidation conditions suggest degradation of contaminants in the downgradient direction. Estimated values of electron potential were assigned to ground water collected in October 2005 from all monitoring sites at the Hazardous Test Area. Moderate to strong reducing conditions were present upgradient from the Open Burn/Open Detonation site, at the site, and at various locations downgradient from the site, but the aquifer contained well-oxygenated water between many of the reducing areas. The spatial variability of reduction-oxidation conditions in the aquifer exemplifies the partial connectivity of the fracture system(s). Dilution of the contaminants i

Ground-water contamination and movement at the Defense General Supply Center, Richmond, Virginia. Water Resources Investigation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Powell, J.D.; Wright, W.G.; Nelms, D.L.

1990-01-01

The report documents the efforts of the USGS in support of the quantification phase of the IRP to determine the degree of contamination of a site that has been identified as requiring study. The report describes the extent, concentration, direction, and rate of movement of contaminants in ground water beyond the boundaries of the DGSC. Hydrologic and geologic data were collected during 1984-90 from wells located upgradient from the DGSC, upgradient from the Area 50 landfill located on the DGSC, in the landfill, in the National Guard Area (NGA) downgradient from the landfill, and downgradient from the NGA beyond themore » eastern boundary of the DGSC. Lithologic data were collected during drilling of wells installed downgradient of the NGA by the USGS during 1984-86. Water from wells located downgradient of the NGA was analyzed for volatile-organic compounds, major cations and anions, priority-pollutant trace metals, and total organic carbon. Aquifer-test wells were installed by the USGS and aquifer testing was performed during 1985.« less

Augmenting groundwater monitoring networks near landfills with slurry cutoff walls.

PubMed

Hudak, Paul F

2004-01-01

This study investigated the use of slurry cutoff walls in conjunction with monitoring wells to detect contaminant releases from a solid waste landfill. The 50 m wide by 75 m long landfill was oriented oblique to regional groundwater flow in a shallow sand aquifer. Computer models calculated flow fields and the detection capability of six monitoring networks, four including a 1 m wide by 50 m long cutoff wall at various positions along the landfill's downgradient boundaries and upgradient of the landfill. Wells were positioned to take advantage of convergent flow induced downgradient of the cutoff walls. A five-well network with no cutoff wall detected 81% of contaminant plumes originating within the landfill's footprint before they reached a buffer zone boundary located 50 m from the landfill's downgradient corner. By comparison, detection efficiencies of networks augmented with cutoff walls ranged from 81 to 100%. The most efficient network detected 100% of contaminant releases with four wells, with a centrally located, downgradient cutoff wall. In general, cutoff walls increased detection efficiency by delaying transport of contaminant plumes to the buffer zone boundary, thereby allowing them to increase in size, and by inducing convergent flow at downgradient areas, thereby funneling contaminant plumes toward monitoring wells. However, increases in detection efficiency were too small to offset construction costs for cutoff walls. A 100% detection efficiency was also attained by an eight-well network with no cutoff wall, at approximately one-third the cost of the most efficient wall-augmented network.

Sorption testing and generalized composite surface complexation models for determining uranium sorption parameters at a proposed in-situ recovery site

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, Raymond H.; Truax, Ryan A.; Lankford, David A.

Solid-phase iron concentrations and generalized composite surface complexation models were used to evaluate procedures in determining uranium sorption on oxidized aquifer material at a proposed U in situ recovery (ISR) site. At the proposed Dewey Burdock ISR site in South Dakota, USA, oxidized aquifer material occurs downgradient of the U ore zones. Solid-phase Fe concentrations did not explain our batch sorption test results,though total extracted Fe appeared to be positively correlated with overall measured U sorption. Batch sorption test results were used to develop generalized composite surface complexation models that incorporated the full genericsorption potential of each sample, without detailedmore » mineralogiccharacterization. The resultant models provide U sorption parameters (site densities and equilibrium constants) for reactive transport modeling. The generalized composite surface complexation sorption models were calibrated to batch sorption data from three oxidized core samples using inverse modeling, and gave larger sorption parameters than just U sorption on the measured solidphase Fe. These larger sorption parameters can significantly influence reactive transport modeling, potentially increasing U attenuation. Because of the limited number of calibration points, inverse modeling required the reduction of estimated parameters by fixing two parameters. The best-fit models used fixed values for equilibrium constants, with the sorption site densities being estimated by the inversion process. While these inverse routines did provide best-fit sorption parameters, local minima and correlated parameters might require further evaluation. Despite our limited number of proxy samples, the procedures presented provide a valuable methodology to consider for sites where metal sorption parameters are required. Furthermore, these sorption parameters can be used in reactive transport modeling to assess downgradient metal attenuation, especially when no other calibration data are available, such as at proposed U ISR sites.« less

Sorption testing and generalized composite surface complexation models for determining uranium sorption parameters at a proposed in-situ recovery site

DOE PAGES

Johnson, Raymond H.; Truax, Ryan A.; Lankford, David A.; ...

2016-02-03

Solid-phase iron concentrations and generalized composite surface complexation models were used to evaluate procedures in determining uranium sorption on oxidized aquifer material at a proposed U in situ recovery (ISR) site. At the proposed Dewey Burdock ISR site in South Dakota, USA, oxidized aquifer material occurs downgradient of the U ore zones. Solid-phase Fe concentrations did not explain our batch sorption test results,though total extracted Fe appeared to be positively correlated with overall measured U sorption. Batch sorption test results were used to develop generalized composite surface complexation models that incorporated the full genericsorption potential of each sample, without detailedmore » mineralogiccharacterization. The resultant models provide U sorption parameters (site densities and equilibrium constants) for reactive transport modeling. The generalized composite surface complexation sorption models were calibrated to batch sorption data from three oxidized core samples using inverse modeling, and gave larger sorption parameters than just U sorption on the measured solidphase Fe. These larger sorption parameters can significantly influence reactive transport modeling, potentially increasing U attenuation. Because of the limited number of calibration points, inverse modeling required the reduction of estimated parameters by fixing two parameters. The best-fit models used fixed values for equilibrium constants, with the sorption site densities being estimated by the inversion process. While these inverse routines did provide best-fit sorption parameters, local minima and correlated parameters might require further evaluation. Despite our limited number of proxy samples, the procedures presented provide a valuable methodology to consider for sites where metal sorption parameters are required. Furthermore, these sorption parameters can be used in reactive transport modeling to assess downgradient metal attenuation, especially when no other calibration data are available, such as at proposed U ISR sites.« less

Groundwater geochemistry of Isla de Mona, Puerto Rico

USGS Publications Warehouse

Wicks, C.M.; Troester, J.W.

1998-01-01

In this study, we explore the differences between the hydrogeochemical processes observed in a setting that is open to input from the land surface and in a setting that is closed with respect to input from the land surface. The closed setting was a water-filled passage in a cave. Samples of groundwater and of a solid that appeared to be suspended in the relatively fresh region of saline-freshwater mixing zone were collected. The solid was determined to be aragonite. Based on the analyses of the composition and saturation state of the groundwater, the mixing of fresh and saline water and precipitation of aragonite are the controlling geochemical processes in this mixing zone. We found no evidence of sulfate reduction. Thus, this mixing zone is similar to that observed in Caleta Xel Ha, Quintana Roo, also a system that is closed with respect to input from the land surface. The open setting was an unconfined aquifer underlying the coastal plain along which four hand-dug wells are located. Two wells are at the downgradient ends of inferred flowpaths and one is along a flowpath. The composition of the groundwater in the downgradient wells is sulfide-rich and brackish. In contrast, at the well located along a flow line, the groundwater is oxygenated and brackish. All groundwater is oversaturated with respect to calcite, aragonite, and dolomite. The composition is attributed to mixing of fresh and saline groundwater, CO2 outgassing, and sulfate reduction. This mixing zone is geochemically similar to that observed in blue holes and cenotes.

Field evidence for a protistan role in an organically-contaminated aquifer

USGS Publications Warehouse

Kinner, Nancy E.; Harvey, Ronald W.; Shay, David M.; Metge, David W.; Warren, Alan

2002-01-01

The association between protists, bacteria, and dissolved organic carbon (DOC) in an oxygen-depleted, 6 km-long wastewater contaminant plume within a sandy aquifer (Cape Cod, MA) was investigated by comparing abundance patterns along longitudinal and vertical transects and at a control site. Strong linear correlations were observed between unattached bacterial abundance and DOC for much of the upgradient-half of the plume (0.1−2.5 km downgradient from the source) that is characterized by quasi-steady state chemistry. However, a logarithmic decrease was observed between the number of protists supported per mg of DOC and the estimated age of the DOC within the plume. The relatively labile dissolved organic contaminants that characterize the groundwater sampled from the plume ≤0.1 km downgradient from the contaminant source appeared to indirectly support 3−4 times as many protists (per mg of DOC) as the older, more recalcitrant DOC in the alkylbenzene sulfonate (ABS)-contaminated zone at 3 km downgradient (∼30 years travel time). Substantive numbers of protists (>104/cm3) were recovered from suboxic zones of the plume. The higher than expected ratios of protists to unattached bacteria (10 to 100:1) observed in much of the plume suggest that protists may be grazing upon both surface-associated and unattached bacterial communities to meet their nutritional requirements. In closed bottle incubation experiments, the presence of protists caused an increase in bacterial growth rate, which became more apparent at higher amendments of labile DOC (3−20 mgC/L). The presence of protists resulted in an increase in the apparent substrate saturation level for the unattached bacterial community, suggesting an important role for protists in the fate of more-labile aquifer organic contaminants.

Monitoring trichloroethene remediation at an iron permeable reactive barrier using stable carbon isotopic analysis

NASA Astrophysics Data System (ADS)

VanStone, Nancy; Przepiora, Andrzej; Vogan, John; Lacrampe-Couloume, Georges; Powers, Brian; Perez, Ernesto; Mabury, Scott; Sherwood Lollar, Barbara

2005-08-01

Stable carbon isotopic analysis, in combination with compositional analysis, was used to evaluate the performance of an iron permeable reactive barrier (PRB) for the remediation of ground water contaminated with trichloroethene (TCE) at Spill Site 7 (SS7), F.E. Warren Air Force Base, Wyoming. Compositional data indicated that although the PRB appeared to be reducing TCE to concentrations below treatment goals within and immediately downgradient of the PRB, concentrations remained higher than expected at wells further downgradient (i.e. > 9 m) of the PRB. At two wells downgradient of the PRB, TCE concentrations were comparable to upgradient values, and δ13C values of TCE at these wells were not significantly different than upgradient values. Since the process of sorption/desorption does not significantly fractionate carbon isotope values, this suggests that the TCE observed at these wells is desorbing from local aquifer materials and was present before the PRB was installed. In contrast, three other downgradient wells show significantly more enriched δ13C values compared to the upgradient mean. In addition, δ13C values for the degradation products of TCE, cis-dichloroethene and vinyl chloride, show fractionation patterns expected for the products of the reductive dechlorination of TCE. Since concentrations of both TCE and degradation products drop to below detection limit in wells within the PRB and directly below it, these downgradient chlorinated hydrocarbon concentrations are attributed to desorption from local aquifer material. The carbon isotope values indicate that this dissolved contaminant is subject to local degradation, likely due to in situ microbial activity.

Monitoring trichloroethene remediation at an iron permeable reactive barrier using stable carbon isotopic analysis.

PubMed

VanStone, Nancy; Przepiora, Andrzej; Vogan, John; Lacrampe-Couloume, Georges; Powers, Brian; Perez, Ernesto; Mabury, Scott; Sherwood Lollar, Barbara

2005-08-01

Stable carbon isotopic analysis, in combination with compositional analysis, was used to evaluate the performance of an iron permeable reactive barrier (PRB) for the remediation of ground water contaminated with trichloroethene (TCE) at Spill Site 7 (SS7), F.E. Warren Air Force Base, Wyoming. Compositional data indicated that although the PRB appeared to be reducing TCE to concentrations below treatment goals within and immediately downgradient of the PRB, concentrations remained higher than expected at wells further downgradient (i.e. >9 m) of the PRB. At two wells downgradient of the PRB, TCE concentrations were comparable to upgradient values, and delta13C values of TCE at these wells were not significantly different than upgradient values. Since the process of sorption/desorption does not significantly fractionate carbon isotope values, this suggests that the TCE observed at these wells is desorbing from local aquifer materials and was present before the PRB was installed. In contrast, three other downgradient wells show significantly more enriched delta13C values compared to the upgradient mean. In addition, delta13C values for the degradation products of TCE, cis-dichloroethene and vinyl chloride, show fractionation patterns expected for the products of the reductive dechlorination of TCE. Since concentrations of both TCE and degradation products drop to below detection limit in wells within the PRB and directly below it, these downgradient chlorinated hydrocarbon concentrations are attributed to desorption from local aquifer material. The carbon isotope values indicate that this dissolved contaminant is subject to local degradation, likely due to in situ microbial activity.

Mapping bedrock surface contours using the horizontal-to-vertical spectral ratio (HVSR) method near the middle quarter srea, Woodbury, Connecticut

USGS Publications Warehouse

Brown, Craig J.; Voytek, Emily B.; Lane, John W.; Stone, Janet R.

2013-01-01

The bedrock surface contours in Woodbury, Connecticut, were determined downgradient of a commercial zone known as the Middle Quarter area (MQA) using the novel, noninvasive horizontal-to-vertical (H/V) spectral ratio (HVSR) passive seismic geophysical method. Boreholes and monitoring wells had been drilled in this area to characterize the shallow subsurface to within 20 feet (ft) of the land surface, but little was known about the deep subsurface, including sediment thicknesses and depths to bedrock (Starn and Brown, 2007; Brown and others, 2009). Improved information on the altitude of the bedrock surface and its spatial variation was needed for assessment and remediation of chlorinated solvents that have contaminated the overlying glacial aquifer that supplies water to wells in the area.

Redox conditions and the efficiency of chlorinated ethene biodegradation: Field studies

USGS Publications Warehouse

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

2000-01-01

The effect of redox conditions on the efficiency of chlorinated ethene biodegradation was investigated at two field sites. One site (NAS Cecil Field, FL) is characterized by predominantly Fe(III)-reducing conditions in the contaminant source area, grading to predominantly sulfate- reducing conditions downgradient. This sequence of redox conditions led to relatively inefficient biodegradation of chlorinated ethenes, with high concentrations of trichloroethene extending more than 400 meters downgradient of the source area. In contrast, a second site (NBS Kings Bay, GA) characterized by predominantly sulfate-reducing conditions in the source area followed by Fe(III)-reducing conditions downgradient. In this system perchloroethene (PCE) and TCE were rapidly biodegraded and extended less than 100 meters downgradient. Rates of ground- water transport are similar at the two sites (???0.2 m/d) indicating that the succession of redox processes, rather than other hydrologic factors, is the principal control on biodegradation. In particular, redox conditions that favor the initial reduction of highly chlorinated ethenes (methanogenic or sulfate-reducing conditions) followed by more oxidizing conditions (Fe(III)- reducing or oxic conditions) favors efficient biodegradation. Thus, documenting the succession of redox processes is an important step in understanding the efficiency of chlorinated ethene biodegradation in ground-water systems.

Effluent migration from septic tank systems in two different lithologies, Broward County, Florida

USGS Publications Warehouse

Waller, B.G.; Howie, Barbara; Causaras, C.R.

1987-01-01

Two septic tank test sites, one in sand and one in limestone, in Broward County, Florida, were analyzed for effluent migration. Groundwater from shallow wells, both in background areas and hydraulically down-gradient of the septic tank system, was sampled during a 16-month period from April 1983 through August 1984. Water quality indicators were used to determine the effluent affected zone near the septic tank systems. Specific conductance levels and concentrations of chloride, sulfate, ammonium, and nitrate indicated effluent movement primarily in a vertical direction with abrupt dilution as it moved down-gradient. Effluent was detected in the sand to a depth more than 20 ft below the septic tank outlet, but was diluted to near background conditions 50 ft down-gradient from the tank. Effluent in the limestone was detected in all three observation wells to depths exceeding 25 ft below the septic tank outlet and was diluted, but still detectable, 40 ft down-gradient. The primary controls on effluent movement from septic tank systems in Broward County are the lithology and layering of the geologic materials, hydraulic gradients, and the volume and type of use the system receives. (Author 's abstract)

Assessing natural attenuation potential at a uranium (U) in situ recovery site (Rosita, TX, USA) using multiple redox-sensitive isotope systems

NASA Astrophysics Data System (ADS)

Basu, A.; Brown, S. T.; Christensen, J. N.; DePaolo, D. J.; Reimus, P. W.; Heikoop, J. M.; Simmons, A. M.; House, B.; Schilling, K.; Johnson, T. M.; Pelizza, M.

2013-12-01

The In Situ Recovery (ISR) U mining operation at Rosita, TX, USA, involved oxidative dissolution of U from roll front U deposits. This process mobilized U along with other characteristic elements (e.g., Se) from the roll fronts in their soluble and toxic oxidized forms (e.g., U(VI), Se(VI)). The dissolved U(VI) in groundwater poses significant ecological risk due to its chemical toxicity and must be restored below the existing regulatory limit to minimize the environmental impact of ISR mining. However, the undisturbed sediments downgradient to the roll front deposits are expected to remain reduced. Naturally occurring Fe-minerals (e.g., FeS, siderite, magnetite) and microorganisms in the sediments downgradient to ISR activity can reduce dissolved U(VI) to less toxic and insoluble U(IV) and promote natural attenuation. The reduction of oxyanions of U or Se induces measurable isotopic fractionation that can be used to monitor the natural attenuation by downgradient sediments. Here, we used multiple redox-sensitive isotope systems (U, Se, and S) to detect reducing conditions and natural attenuation of U(VI) at the ISR site. We collected groundwater samples from 26 wells located in the ore body, upgradient and downgradient to the ore body. The δ238U values measured in groundwater samples from 23 wells range from 0.48‰ to -1.66‰ (×0.12‰). A preliminary investigation of 6 groundwater samples shows a variation of δ82Se values from -1.44‰ to 5.24‰ (×0.15‰). The δ34SO4 measurements in groundwater vary from 11.8‰ to -19.9‰. The reduction of Se(VI) and SO42- fractionates the lighter isotopes (i.e., 32S and 76Se) in the reduced product phase rendering the remaining reactants in the groundwater enriched in heavier isotopes. Therefore, the high δ82Se and δ34SO4 values may suggest reduction of Se(VI) and SO42-, respectively. The highest δ238U values are observed in the wells located in the ore body or upgradient to the ore body whereas the downgradient wells show significantly lower δ238U values. High δ238U values in most of the wells located in the ore-zone may be attributed to the dissolution of the U ore enriched in 238U. The low δ238U values are generally observed in the wells with low U(VI) concentrations. Since U(VI) reduction fractionates 238U to the solid U(IV) phase, the depletion of 238U in the groundwater samples in the downgradient monitoring wells suggest U(VI) reduction by the downgradient sediments. The δ238U values in the groundwater samples conform to a Rayleigh distillation model with an isotopic fractionation factor α = 1.00013 × 0.00010. Future investigations include characterization of the U ore bearing sediments collected from boreholes in the ore body and downgradient of the ore body, measurement of the δ238U and δ82Se values in the ore and in remaining groundwater samples. The U(VI) reducing capacity and concomitant U isotopic fractionation factors for the sediments from downgradient boreholes will be determined from the batch incubation experiments and flow through column experiments.

Geochemical and Hydrologic Factors Controlling Subsurface Transport of Poly- and Perfluoroalkyl Substances, Cape Cod, Massachusetts.

PubMed

Weber, Andrea K; Barber, Larry B; LeBlanc, Denis R; Sunderland, Elsie M; Vecitis, Chad D

2017-04-18

Growing evidence that certain poly- and perfluoroalkyl substances (PFASs) are associated with negative human health effects prompted the U.S. Environmental Protection Agency to issue lifetime drinking water health advisories for perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) in 2016. Given that groundwater is a major source of drinking water, the main objective of this work was to investigate geochemical and hydrological processes governing the subsurface transport of PFASs at a former fire training area (FTA) on Cape Cod, Massachusetts, where PFAS-containing aqueous film-forming foams were used historically. A total of 148 groundwater samples and 4 sediment cores were collected along a 1200-m-long downgradient transect originating near the FTA and analyzed for PFAS content. The results indicate that unsaturated zones at the FTA and at hydraulically downgradient former domestic wastewater effluent infiltration beds both act as continuous PFAS sources to the groundwater despite 18 and 20 years of inactivity, respectively. Historically different PFAS sources are evident from contrasting PFAS composition near the water table below the FTA and wastewater-infiltration beds. Results from total oxidizable precursor assays conducted using groundwater samples collected throughout the plume suggest that some perfluoroalkyl acid precursors at this site are transporting with perfluoroalkyl acids.

Geochemical and hydrologic factors controlling subsurface transport of poly- and perfluoroalkyl substances, Cape Cod, Massachusetts

USGS Publications Warehouse

Weber, Andrea K.; Barber, Larry B.; LeBlanc, Denis R.; Sunderland, Elsie M.; Vecitis, Chad D.

2017-01-01

Growing evidence that certain poly- and perfluoroalkyl substances (PFASs) are associated with negative human health effects prompted the U.S. Environmental Protection Agency to issue lifetime drinking water health advisories for perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) in 2016. Given that groundwater is a major source of drinking water, the main objective of this work was to investigate geochemical and hydrological processes governing the subsurface transport of PFASs at a former fire training area (FTA) on Cape Cod, Massachusetts, where PFAS-containing aqueous film-forming foams were used historically. A total of 148 groundwater samples and 4 sediment cores were collected along a 1200-m-long downgradient transect originating near the FTA and analyzed for PFAS content. The results indicate that unsaturated zones at the FTA and at hydraulically downgradient former domestic wastewater effluent infiltration beds both act as continuous PFAS sources to the groundwater despite 18 and 20 years of inactivity, respectively. Historically different PFAS sources are evident from contrasting PFAS composition near the water table below the FTA and wastewater-infiltration beds. Results from total oxidizable precursor assays conducted using groundwater samples collected throughout the plume suggest that some perfluoroalkyl acid precursors at this site are transporting with perfluoroalkyl acids.

Field Testing of Downgradient Uranium Mobility at an In-Situ Recovery Uranium Mine

NASA Astrophysics Data System (ADS)

Reimus, P. W.; Clay, J. T.; Rearick, M.; Perkins, G.; Brown, S. T.; Basu, A.; Chamberlain, K.

2015-12-01

In-situ recovery (ISR) mining of uranium involves the injection of O2 and CO2 (or NaHCO3) into saturated roll-front deposits to oxidize and solubilize the uranium, which is then removed by ion exchange at the surface and processed into U3O8. While ISR is economical and environmentally-friendly relative to conventional mining, one of the challenges of extracting uranium by this process is that it leaves behind a geochemically-altered aquifer that is exceedingly difficult to restore to pre-mining geochemical conditions, a regulatory objective. In this research, we evaluated the ability of the aquifer downgradient of an ISR mining area to attenuate the transport of uranium and other problem constituents that are mobilized by the mining process. Such an evaluation can help inform both regulators and the mining industry as to how much restoration of the mined ore zone is necessary to achieve regulatory compliance at various distances downgradient of the mining zone even if complete restoration of the ore zone proves to be difficult or impossible. Three single-well push-pull tests and one cross-well test were conducted in which water from an unrestored, previously-mined ore zone was injected into an unmined ore zone that served as a geochemical proxy for the downgradient aquifer. In all tests, non-reactive tracers were injected with the previously-mined ore zone water to allow the transport of uranium and other constituents to be compared to that of the nonreactive species. In the single-well tests, it was shown that the recovery of uranium relative to the nonreactive tracers ranged from 12-25%, suggesting significant attenuation capacity of the aquifer. In the cross-well test, selenate, molybdate and metavanadate were injected with the unrestored water to provide information on the transport of these potentially-problematic anionic constituents. In addition to the species-specific transport information, this test provided valuable constraints on redox conditions within the system, as redox couples involving these species collectively bracket the predicted transition redox potential for the U(VI)/U(IV) couple. Reduction should provide much longer-lasting immobilization of constituents than adsorption, especially given the inherent reducing characteristics of roll-front systems.

Effects of effluents from a coal-fired, electric-generating powerplant on local ground water near Hayden, Colorado

USGS Publications Warehouse

Ellis, S.R.; Mann, P.G.

1981-01-01

Data were collected at the Hayden, Colo., powerplant for about a year during 1978-79 to monitor the effects of effluent and raw-water storage ponds on the local ground water, Sage Creek, and the Yampa River. The concentration of boron in wells downgradient from the effluent ponds indicated that the ponds were leaking, increasing the average boron concentrations in the ground water to a level in excess of the standards for agricultural use of water. Water from seeps, probably the best indicators of downgradient water quality, had average concentrations of boron two times that of the Colorado Department of Health (1977) standard for agricultural use of water. Chemical analyses of water from wells and the discharge weir downgradient from the raw-water storage ponds indicated these ponds are leaking. The effect of this leakage is that the water in wells downgradient from these ponds has a lower specific conductance and a lower boron concentration than the water in wells downgradient from the effluent ponds. The concentration of trace elements in the water from the wells and the discharge weir generally declined during the study, probably because the ground water was recovering from the effects of a plume from the raw-water pond previously used for fly-ash disposal. The effluents from the Hayden powerplant lowered the specific conductance and the iron and manganese concentrations, increased the concentration of boron, and had little or no effect on the selenium concentration in Sage Creek. Sage Creek had no discernible effect on the Yampa River because the volume of water in the Yampa River was so much greater. The effluents from the powerplant also had no discernible effect on the Yampa River. (USGS)

2011 Mound Site Groundwater Plume Rebound Exercise and Follow-Up - 13440

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hooten, Gwendolyn; Cato, Rebecca; Lupton, Greg

2013-07-01

The Mound Site facility near Miamisburg, Ohio, opened in 1948 to support early atomic weapons programs. It grew into a research, development, and production facility performing work in support of the U.S. Department of Energy (DOE) weapons and energy programs. The plant was in operation until 1995. During the course of operation, an onsite landfill was created. The landfill was located over a finger of a buried valley aquifer, which is a sole drinking water source for much of the Miami Valley. In the 1980's, volatile organic compounds (VOCs) were discovered in groundwater at the Mound site. The site wasmore » placed on the National Priorities List on November 21, 1989. DOE signed a Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) Federal Facility Agreement with the U.S. Environmental Protection Agency (EPA) and the Ohio Environmental Protection Agency. The agreement became effective in October 1990. The area that included the landfill was designated Operational Unit 1 (OU-1). In 1995, a Record of Decision was signed that called for the installation and operation of a pump and treatment (P and T) system in order to prevent the VOCs in OU-1 groundwater from being captured by the onsite water production wells. In addition to the P and T system, a soil vapor extraction (SVE) system was installed in 1997 to accelerate removal of VOCs from groundwater in the OU-1 area. The SVE system was successful in removing large amounts of VOCs and continued to operate until 2007, when the amount of VOCs removed became minimal. A rebound study was started in February 2003 to determine how the groundwater system and contaminants would respond to shutting down the P and T system. The rebound test was stopped in February 2004 because predetermined VOC threshold concentrations were exceeded down-gradient of the landfill. The P and T and SVE systems were restarted after the termination of the rebound test. In 2006, the remediation of the Mound site was completed and the site was declared to be protective of human health and the environment, as long as the institutional controls are observed. The institutional controls that apply to the OU-1 area include provisions that no soil be allowed to leave the site, no wells be installed for drinking water, and the site may be approved only for industrial use. The onsite landfill with the operating CERCLA remedy remained. However, the Mound Development Corporation lobbied Congress for funds to remediate the remaining onsite landfill to allow for property reuse. In 2007 DOE received funding from Congress to perform non-CERCLA removal actions at OU-1 to excavate the site sanitary landfill. In 2009, DOE received American Recovery and Reinvestment Act funding to complete the project. Excavation of the landfill occurred intermittently from 2006 through 2010 and the majority of the VOC source was removed; however, VOC levels near the P and T system remained greater than the EPA maximum contaminant levels (MCLs). Presently, groundwater is contained using two extraction wells to create a hydraulic barrier to prevent down-gradient migration of VOC-impacted groundwater. Since the primary contamination source has been removed, the feasibility of moving away from containment to a more passive remedy, namely monitored natural attenuation (MNA), is being considered. A second rebound study was started in June 2011. If contaminant and groundwater behavior met specific conditions during the study, MNA would be evaluated and considered as a viable alternative for the groundwater in the OU-1 area. From June through December 2011, the second rebound study evaluated the changes in VOC concentrations in groundwater when the P and T system was not in operation. As the study progressed, elevated concentrations of VOCs that exceeded predetermined trigger values were measured along the down-gradient boundary of the study area, and so the P and T system was restarted. It was determined that a discrete area with VOC concentrations greater than the MCLs was present in groundwater down-gradient of the extraction wells. The source was not identified, but the contamination was thought not to be caused by residually contaminated soil beneath the former landfill. The data collected so far supports the consideration of MNA as a viable alternative to hydraulic containment. Additional investigations are being performed to identify possible sources or pathways of VOCs in groundwater that may be contributing to the elevated VOC levels measured down-gradient of the extraction well system. Data from this additional investigation will be used to determine whether the VOCs detected down-gradient of the hydraulic boundary are the result of residual soil contamination, a previously unknown contribution of VOC-contaminated water entering the groundwater outside the capture zone of the extraction wells, or a pulse of VOC-contaminated groundwater from the OU-1 landfill that occurred during the rebound study. (authors)« less

Ground-water levels, flow, and quality in northwestern Elkhart County, Indiana, 1980-89

USGS Publications Warehouse

Duwelius, R.F.; Silcox, C.A.

1991-01-01

The time of peak dissolved-bromide concentrations in water from shallow wells downgradient from the landfill was used to estimate a rate of horizontal flow of water in the unconfined aquifer. The average rate of flow between shallow wells downgradient from the landfill was estimated to be 1.2 feet per day. This rate is within the range of values for ground-water flow calculated according to Darcy's law.

Ground-water quality, levels, and flow direction near Fort Cobb Reservoir, Caddo County, Oklahoma, 1998-2000

USGS Publications Warehouse

Becker, Carol J.

2001-01-01

Fort Cobb Reservoir in northwest Caddo County Oklahoma is managed by the Bureau of Reclamation for water supply, recreation, flood control, and wildlife. Excessive amounts of nitrogen in the watershed have the potential to cause long-term eutrophication of the reservoir and increase already elevated concentrations of nitrogen in the Rush Springs aquifer. The U.S. Geological Survey in cooperation with the Bureau of Reclamation studied ground water in the area surrounding a swine feeding operation located less than 2 miles upgradient from Fort Cobb Reservoir in Caddo County, Oklahoma. Objectives of the study were to (1) determine if the operation was contributing nitrogen to the ground water and (2) measure changes in ground-water levels and determine the local ground-water flow direction in the area surrounding the swine feeding operation. Nitrate concentrations (28.1 and 31.5 milligrams per liter) were largest in two ground-water samples from a well upgradient of the wastewater lagoon. Nitrate concentrations ranged from 4.30 to 8.20 milligrams per liter in samples from downgradient wells. Traces of ammonia and nitrite were detected in a downgradient well, but not in upgradient wells. d15N values indicate atmospheric nitrogen, synthetic fertilizer, or plants were the predominate sources of nitrate in ground water from the downgradient wells. The d15N values in these samples are depleted in nitrogen-15, indicating that animal waste was not a significant contributor of nitrate. Manganese concentrations (1,150 and 965 micrograms per liter) in samples from a downgradient well were substantially larger than concentrations in samples from other wells, exceeding the secondary drinking-water standard of 50 micrograms per liter. Larger concentrations of bicarbonate, magnesium, fluoride, and iron and a higher pH were also measured in water from a downgradient well. Ground-water levels in an observation well were higher from April to mid-July and lower during the late summer and in the fall due to a seasonal decrease in precipitation, increase in water withdrawals, and increase in evapotranspiration. Ground water near the wastewater spray field moved south-southeast toward Willow Creek along a gradient of about 50 feet per mile. Analysis of ground-water samples suggest that commercial fertilizer is contributing nitrate upgradient of the swine feeding operation and that wastewater from the lagoon is contributing reduced forms of nitrogen, ammonia and nitrite. Additional downgradient wells would be needed to (1) determine if the swine feeding operation is adding excessive amounts of nitrogen to ground water, (2) determine the vertical dimension of wastewater flow, and (3) the extent of wastewater downgradient of the lagoon.

Dichlorobenzene in ground water: Evidence for long-term persistence

USGS Publications Warehouse

Barber, L.B.

1988-01-01

Hydrologic and geochemical evidence were used to establish the long-term persistence of dichlorobenzene in ground water that has been contaminated from 50 years of rapid-infiltration sewage disposal. An extensive plume of dichlorobenzene extends more than 3,500 meters downgradient from the disposal beds, with concentrations of the combined isomers ranging from less than 0.01 to over 1.0 ??g/l. Based on estimates of maximum ground-water flow velocities, a minimum age of 20 years was established for the farthest downgradient zone of dichlorobenzene contamination. Branched-chained, alkylbenzenesulfonic acid surfactants, that were introduced into the ground water prior to 1966, occur along with dichlorobenzene in the downgradient part of the plume, further establish residence of the compounds in the aquifer for at least 20 years. Although dichlorobenzene can be biologically degraded under aerobic conditions, its persistence at this field site is attributed to the dynamics of the ground-water system. Denitrifying conditions, resulting from the degradation of organic compounds in the aquifer near the disposal beds, appear to have enhanced the persistence of dichlorobenzene, which is not degraded by anaerobic bacteria. Biological degradation of dichlorobenzene in the aerobic part of the plume downgradient from the source is probably limited by the paucity of a suitable organic-carbon substrate and the low concentrations of dissolved oxygen in the contaminated ground water.

US Environmental rotection Agency's strategy for ground-water-quality monitoring at hazardous-waste land-disposal facilities located in karst terranes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Field, M.S.

1988-11-01

Ground-water monitoring of hazardous-waste land-disposal units by a network of wells is ineffective when located in karstic terranes. The U.S. Environmental Protection Agency (EPA) is currently proposing to modify its current ground-water-quality monitoring requirement of one upgradient well and three downgradient wells for disposal units located in karstic terranes. The convergent nature of subsurface flow to cave streams in karstic terranes requires that effective monitoring wells intercept the cave streams. Wells located around a hazardous-waste disposal unit, but not in the specific cave stream draining the site, are only providing irrelevant data and a false sense of security because themore » water samples from such wells are not necessarily from the hazardous-waste disposal unit. A case study is provided in this paper. EPA is drafting a guidance document that will allow monitoring by wells, only if the up- and down-gradient wells can be demonstrated to be hydraulically connected by means of dye-trace studies. If not, then the monitoring of springs shown to be hydraulically connected to the facility by dye-tracing studies would be required. Monitoring for sinkhole development will also be required to provide advance warning of sinkhole collapse. The investigation and determination of the probability of sinkhole collapse is given special treatment.« less

Eddy heat flux across the Antarctic Circumpolar Current estimated from sea surface height standard deviation

NASA Astrophysics Data System (ADS)

Foppert, Annie; Donohue, Kathleen A.; Watts, D. Randolph; Tracey, Karen L.

2017-08-01

Eddy heat flux (EHF) is a predominant mechanism for heat transport across the zonally unbounded mean flow of the Antarctic Circumpolar Current (ACC). Observations of dynamically relevant, divergent, 4 year mean EHF in Drake Passage from the cDrake project, as well as previous studies of atmospheric and oceanic storm tracks, motivates the use of sea surface height (SSH) standard deviation, H*, as a proxy for depth-integrated, downgradient, time-mean EHF (>[EHF>¯>]) in the ACC. Statistics from the Southern Ocean State Estimate corroborate this choice and validate throughout the ACC the spatial agreement between H* and >[EHF>¯>] seen locally in Drake Passage. Eight regions of elevated >[EHF>¯>] are identified from nearly 23.5 years of satellite altimetry data. Elevated cross-front exchange usually does not span the full latitudinal width of the ACC in each region, implying a hand-off of heat between ACC fronts and frontal zones as they encounter the different >[EHF>¯>] hot spots along their circumpolar path. Integrated along circumpolar streamlines, defined by mean SSH contours, there is a convergence of ∮>[EHF>¯>] in the ACC: 1.06 PW enters from the north and 0.02 PW exits to the south. Temporal trends in low-frequency [EHF] are calculated in a running-mean sense using H* from overlapping 4 year subsets of SSH. Significant increases in downgradient [EHF] magnitude have occurred since 1993 at Kerguelen Plateau, Southeast Indian Ridge, and the Brazil-Malvinas Confluence, whereas the other five >[EHF>¯>] hot spots have insignificant trends of varying sign.

Geochemical processes in ground water resulting from surface mining of coal at the Big Sky and West Decker Mine areas, southeastern Montana

USGS Publications Warehouse

Clark, D.W.

1995-01-01

A potential hydrologic effect of surface mining of coal in southeastern Montana is a change in the quality of ground water. Dissolved-solids concen- trations in water in spoils aquifers generally are larger than concentrations in water in the coal aquifers they replaced; however, laboratory experiments have indicated that concentrations can decrease if ground water flows from coal-mine spoils to coal. This study was conducted to determine if decreases in concentrations occur onsite and, if so, which geochemical processes caused the decreases. Solid-phase core samples of spoils, unmined over- burden, and coal, and ground-water samples were collected from 16 observation wells at two mine areas. In the Big Sky Mine area, changes in ground- water chemistry along a flow path from an upgradient coal aquifer to a spoils aquifer probably were a result of dedolomitization. Dissolved-solids concentrations were unchanged as water flowed from a spoils aquifer to a downgradient coal aquifer. In the West Decker Mine area, dissolved-solids concentrations apparently decreased from about 4,100 to 2,100 milligrams per liter as water moved along an inferred flow path from a spoils aquifer to a downgradient coal aquifer. Geochemical models were used to analyze changes in water chemistry on the basis of results of solid-phase and aqueous geochemical characteristics. Geochemical processes postulated to result in the apparent decrease in dissolved-solids concentrations along this inferred flow path include bacterial reduction of sulfate, reverse cation exchange within the coal, and precipitation of carbonate and iron-sulfide minerals.

Investigation clogging dynamic of permeable pavement systems using embedded sensors

NASA Astrophysics Data System (ADS)

Razzaghmanesh, Mostafa; Borst, Michael

2018-02-01

Permeable pavement is a stormwater control measure commonly selected in both new and retrofit applications. However, there is limited information about the clogging mechanism of these systems that effects the infiltration. A permeable pavement site located at the Seitz Elementary School, on Fort Riley, Kansas was selected for this study. An 80-space parking lot was built behind the school as part of an EPA collaboration with the U.S. Army. The parking lot design includes a permeable interlocking concrete pavement section along the downgradient edge. This study monitored the clogging progress of the pavement section using twelve water content reflectometers and three buried tipping bucket rain gauges. This clogging dynamic investigation was divided into three stages namely pre-clogged, transitional, and clogged. Recorded initial relative water content of all three stages were significantly and negatively correlated to antecedent dry weather periods with stronger correlations during clogged conditions. The peak relative water content correlation with peak rainfall 10-min intensity was significant for the water content reflectometers located on the western edge away from the eastern edge; this correlation was strongest during transition stage. Once clogged, rainfall measurements no longer correlated with the buried tipping bucket rain gauges. Both water content reflectometers and buried tipping bucket rain gauges showed the progress of surface clogging. For every 6 mm of rain, clogging advanced 1 mm across the surface. The results generally support the hypothesis that the clogging progresses from the upgradient to the downgradient edge. The magnitude of the contributing drainage area and rainfall characteristics are effective factors on rate and progression of clogging.

Approach to the vadose zone monitoring in hazardous and solid waste disposal facilities

NASA Astrophysics Data System (ADS)

Twardowska, Irena

2004-03-01

In the solid waste (SW)disposal sites, in particular at the unlined facilities, at the remediated or newly-constructed units equipped with novel protective/reactive permeable barriers or at lined facilities with leachate collection systems that are prone to failure, the vadose zone monitoring should comprise besides the natural soil layer beneath the landfill, also the anthropogenic vadose zone, i.e. the waste layer and pore solutions in the landfill. The vadose zone screening along the vertical profile of SW facilities with use of direct invasive soil-core and soil-pore liquid techniques shows vertical downward redistribution of inorganic (macroconstituents and heavy metals) and organic (PAHs) contaminant loads in water infiltrating through the waste layer. These loads can make ground water down-gradient of the dump unfit for any use. To avoid damage of protective/reactive permeable barriers and liners, an installation of stationary monitoring systems along the waste layer profile during the construction of a landfill, which are amenable to generate accurate data and information in a near-real time should be considered including:(i) permanent samplers of pore solution, with a periodic pump-induced transport of collected solution to the surface, preferably with instant field measurements;(ii)chemical sensors with continuous registration of critical parameters. These techniques would definitely provide an early alert in case when the chemical composition of pore solution percolating downward the waste profile shows unfavorable transformations, which indicate an excessive contaminant load approaching ground water. The problems concerning invasive and stationary monitoring of the vadose zone in SW disposal facilities will be discussed at the background of results of monitoring data and properties of permeable protective/reactive barriers considered for use.

Ground-water quality near the northwest 58th Street solid-waste disposal facility, Dade County, Florida

USGS Publications Warehouse

Mattraw, H.C.; Hull, John E.; Klein, Howard

1978-01-01

The Northwest 58th Street solid-waste disposal facility, 3 miles west of a major Dade County municipal water-supply well field, overlays the Biscayne aquifer, a permeable, solution-riddled limestone which transmits leachates eastward at a calculated rate of 2.9 feet per day. A discrete, identifiable leachate plume has been recognized under and downgradient from the waste disposal facility. Concentrations of sodium, ammonia, and dissolved solids decreased with depth beneath the disposal area and downgradient in response to an advective and convective dispersion. At a distance of about one-half downgradient, the rate of contribution of leachate from the source to the leading edge of the plume was about equal to the rate of loss of leachate from the leading edge of the plume by diffusion and dilution by rainfall infiltration during the period August 1973 - July 1975. Heavy metals and pesticides are filtered, adsorbed by aquifer materials, or are precipitated near the disposal area. (Woodard-USGS)

Calculating ground water transit time of horizontal flow through leaky aquifers.

PubMed

Braunsfurth, Angelika C; Schneider, Wilfried

2008-01-01

The calculation of ground water transit times is one important factor in ground water protection. In this paper, we present an analytical solution for the transit time for a Dupuit-type flow system applicable to saturated flow through a horizontal leaky aquifer discharging to a downgradient fixed-head boundary under steady-state conditions. We investigate the influence of leakage when comparing the resulting travel times of our model based on head-dependent leakage with the commonly used model with no leakage and a simplified model with constant leakage. The results show significant differences in the position of the water divide and transit time, suggesting that leakage cannot be ignored.

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

USGS Publications Warehouse

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

1991-01-01

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.

Rare Earth Element Concentrations and Fractionation Patterns Along Groundwater Flow Paths in Two Different Aquifer Types (i.e., Sand vs. Carbonate)

NASA Astrophysics Data System (ADS)

Johannesson, K. H.; Tang, J.

2003-12-01

Groundwater samples were collected in two different types of aquifer (i.e., Carrizo Sand Aquifer, Texas and Upper Floridan carbonate Aquifer, west-central Florida) to study the concentrations, fractionation, and speciation of rare earth elements (REE) along groundwater flow paths in each aquifer. Major solutes and dissolved organic carbon (DOC) were also measured in these groundwaters. The Carrizo Sand aquifer was sampled in October 2002 and June 2003, whereas, to date, we have only sampled the Floridan once (i.e., June 2003). The data reveal no significant seasonal differences in major solute and REE concentrations for the Carrizo. In Carrizo sand aquifer, groundwaters from relatively shallow wells (i.e., less than 167 m) in the recharge zone are chiefly Ca-Na-HCO3-Cl type waters. With flow down-gradient the groundwaters shift composition to the Na-HCO3 waters. pH and alkalinity initially decrease with flow away from the recharge zone before increasing again down-gradient. DOC is generally low (0.65 mg/L) along the flow path. REE concentrations are highest in groundwaters from the recharge zone (Nd 40.5 pmol/kg), and decrease substantially with flow down-gradient reaching relatively low and stable values (Nd 4.1-8.6 pmol/kg) roughly 10 km from the recharge zone. Generally, Carrizo groundwaters exhibit HREE-enriched shale-normalized patterns. The HREE enrichments are especially strong for waters from the recharge zone [(Yb/Nd)SN =1.7-5.6], whereas down-gradient (deep) groundwaters have flatter patterns [(Yb/Nd)SN =0.7-2.5]. All groundwaters have slightly positive Eu anomalies (Eu/Eu* 0.09-0.14) and negative Ce anomalies (Ce/Ce* -0.85 - -0.07). In the Upper Floridan Aquifer, Ca, Mg, SO4, and Cl concentrations generally increase along groundwater flow path, whereas pH and alkalinity generally decrease. DOC is higher (0.64 - 2.29 mg/L) than in the Carrizo and initially increases along the flow path and then decreases down-gradient. LREE (Nd) concentrations generally increase along groundwater flow path, however, MREE (Gd) exhibit little change and HREE (Yb) concentrations tend to decreases along the flow path. Floridan groundwaters have HREE enriched shale-normalized patterns, although (Yb/Nd)SN values decrease along groundwater flow path. Thus, REE patterns of Floridan groundwaters tend to flatten with flow down-gradient. All groundwaters show positive Eu anomalies (0.06 - 0.17) and negative Ce anomalies (-0.12 - -0.63).

Water levels and groundwater and surface-water exchanges in lakes of the northeast Twin Cities Metropolitan Area, Minnesota, 2002 through 2015

USGS Publications Warehouse

Jones, Perry M.; Trost, Jared J.; Erickson, Melinda L.

2016-10-19

OverviewThis study assessed lake-water levels and regional and local groundwater and surface-water exchanges near northeast Twin Cities Metropolitan Area lakes applying three approaches: statistical analysis, field study, and groundwater-flow modeling.  Statistical analyses of lake levels were completed to assess the effect of physical setting and climate on lake-level fluctuations of selected lakes. A field study of groundwater and surface-water interactions in selected lakes was completed to (1) estimate potential percentages of surface-water contributions to well water across the northeast Twin Cities Metropolitan Area, (2) estimate general ages for waters extracted from the wells, and (3) assess groundwater inflow to lakes and lake-water outflow to aquifers downgradient from White Bear Lake.  Groundwater flow was simulated using a steady-state, groundwater-flow model to assess regional groundwater and surface-water exchanges and the effects of groundwater withdrawals, climate, and other factors on water levels of northeast Twin Cities Metropolitan Area lakes.

Ground-water quality in the vicinity of landfill sites, southern Franklin County, Ohio

USGS Publications Warehouse

De Roche, J.T.; Razem, A.C.

1981-01-01

The hydrogeology and ground-water quality in the vicinity of five landfills in southern Franklin County, Ohio, were investigated by use of data obtained from 46 existing wells, 1 seep, 1 surface-water site, and 1 leachate-collection site. Interpretation was based on data from the wells, a potentiometric-surface map, and chemical analyses. Four of the five landfills are in abandoned sand and gravel pits. Pumping of water from a quarry near the landfills has modified the local ground-water flow pattern, increased the hydraulic gradient, and lowered the water table. Ground water unaffected by the landfills is a hard, calcium bicarbonate type with concentrations of dissolved iron and dissolved sulfate as great as 3.0 milligrams per liter and 200 milligrams per liter, respectively. Water sampled from wells downgradient from two landfills shows an increase in sodium, chloride, and other constituents. The change in water quality cannot be traced directly to the landfills, however, because of well location and the presence of other potential sources of contamination. Chemical analysis of leachate from a collection unit at one landfill shows significant amounts of zinc, chromium, copper, and nickel, in addition to high total organic carbon, biochemical oxygen demand, and organic nitrogen. Concentrations of chloride, iron, lead, manganese and phenolic compounds exceed Ohio Environmental Protection Agency Water Quality Standards for drinking water. Water from unaffected wells within the study area have relatively small amounts of these constituents. (USGS)

Microbial control of mineral–groundwater equilibria:Macroscale to microscale

USGS Publications Warehouse

Bennett, Philip C.; Hiebert, Franz K.; Roger, Jennifer Roberts

2000-01-01

macroscaleprocesses that perturb general groundwater chemistry and therefore mineral–water equilibria; and microscale interactions, where attached organisms locally perturb mineral–water equilibria, potentially releasing limiting trace nutrients from the dissolving mineral.In the contaminated unconfined glacio-fluvial aquifer near Bemidji, Minnesota, USA, carbonate chemistry is influenced primarily at the macroscale. Under oxic conditions, respiration by native aerobic heterotrophs produces excess carbon dioxide that promotes calcite and dolomite dissolution. Aerobic microorganisms do not colonize dolomite surfaces and few occur on calcite. Within the anoxic groundwater, calcite overgrowths form on uncolonized calcite cleavage surfaces, possibly due to the consumption of acidity by dissimilatory iron-reducing bacteria. As molecular oxygen concentration increases downgradient of the oil pool, aerobes again dominate and residual hydrocarbons and ferrous iron are oxidized, resulting in macroscale carbonate-mineral dissolution and iron precipitation.

Mercury speciation and mobilization in a wastewater-contaminated groundwater plume

USGS Publications Warehouse

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

2013-01-01

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

Five-year performance monitoring of a high-density polyethylene (HDPE) cover system at a reclaimed mine waste rock pile in the Sydney Coalfield (Nova Scotia, Canada).

PubMed

Power, Christopher; Ramasamy, Murugan; MacAskill, Devin; Shea, Joseph; MacPhee, Joseph; Mayich, David; Baechler, Fred; Mkandawire, Martin

2017-12-01

Cover systems are commonly placed over waste rock piles (WRPs) to limit atmospheric water and oxygen ingress and control the generation and release of acid mine drainage (AMD) to the receiving environment. Although covers containing geomembranes such as high-density polyethylene (HDPE) exhibit the attributes to be highly effective, there are few, if any, published studies monitoring their performance at full-scale WRPs. In 2011, a HDPE cover was installed over the Scotchtown Summit WRP in Nova Scotia, Canada, and extensive field performance monitoring was conducted over the next five years. A range of parameters within the atmosphere, cover, waste rock, groundwater and surface water, were monitored and integrated into a comprehensive hydrogeochemical conceptual model to assess (i) atmospheric ingress to the waste rock, (ii) waste rock acidity and depletion and (iii) evolution of groundwater and surface water quality. Results demonstrate that the cover is effective and meeting site closure objectives. Depletion in oxygen influx resulted in slower sulphide oxidation and AMD generation, while a significant reduction in water influx (i.e. 512 to 50 mm/year) resulted in diminished AMD release. Consistent improvements in groundwater quality (decrease in sulphate and metals; increase in pH) beneath and downgradient of the WRP were observed. Protection and/or significant improvement in surface water quality was evident in all surrounding watercourses due to the improved groundwater plume and elimination of contaminated runoff over previously exposed waste rock. A variably saturated flow and contaminant transport model is currently being developed to predict long-term cover system performance.

Ground and surface water developmental toxicity at a municipal landfill--Description and weather-related variation

USGS Publications Warehouse

Bruner, M.A.; Rao, M.; Dumont, J.N.; Hull, M.; Jones, T.; Bantle, J.A.

1998-01-01

Contaminated groundwater poses a significant health hazard and may also impact wildlife such as amphibians when it surfaces. Using FETAX (Frog Embryo Teratogenesis Assay-Xenopus), the developmental toxicity of ground and surface water samples near a closed municipal landfill at Norman, OK, were evaluated. The groundwater samples were taken from a network of wells in a shallow, unconfined aquifer downgradient from the landfill. Surface water samples were obtained from a pond and small stream adjacent to the landfill. Surface water samples from a reference site in similar habitat were also analyzed. Groundwater samples were highly toxic in the area near the landfill, indicating a plume of toxicants. Surface water samples from the landfill site demonstrated elevated developmental toxicity. This toxicity was temporally variable and was significantly correlated with weather conditions during the 3 days prior to sampling. Mortality was negatively correlated with cumulative rain and relative humidity. Mortality was positively correlated with solar radiation and net radiation. No significant correlations were observed between mortality and weather parameters for days 4–7 preceding sampling.

Fifteen-year assessment of a permeable reactive barrier for treatment of chromate and trichloroethylene in groundwater.

PubMed

Wilkin, Richard T; Acree, Steven D; Ross, Randall R; Puls, Robert W; Lee, Tony R; Woods, Leilani L

2014-01-15

The fifteen-year performance of a granular iron, permeable reactive barrier (PRB; Elizabeth City, North Carolina) is reviewed with respect to contaminant treatment (hexavalent chromium and trichloroethylene) and hydraulic performance. Due to in-situ treatment of the chromium source zone, reactive and hydraulic longevity of the PRB has outlived the mobile chromate plume. Chromium concentrations exceeding 3 μg/L have not been detected in regions located hydraulically down-gradient of the PRB. Trichloroethylene treatment has also been effective, although non-constant influent concentrations of trichloroethylene have at times resulted in incomplete dechlorination. Daughter products: cis-1,2-dichloroethylene, vinyl chloride, ethene, and ethane have been observed within and down-gradient of the PRB at levels <10% of the influent trichloroethylene. Analysis of potentiometric surfaces up-gradient and across the PRB suggests that the PRB may currently represent a zone of reduced hydraulic conductivity; however, measurements of the in-situ hydraulic conductivity provide values in excess of 200 m/d in some intervals and indicate no discernible loss of bulk hydraulic conductivity within the PRB. The results presented here are particularly significant because they provide the longest available record of performance of a PRB. The longevity of the Elizabeth City PRB is principally the result of favorable groundwater geochemistry and hydrologic properties of the site. © 2013.

Prevalence of antibiotic resistance genes in bacterial communities associated with Cladophora glomerata mats along the nearshore of Lake Ontario.

PubMed

Ibsen, Michael; Fernando, Dinesh M; Kumar, Ayush; Kirkwood, Andrea E

2017-05-01

The alga Cladophora glomerata can erupt in nuisance blooms throughout the lower Great Lakes. Since bacterial abundance increases with the emergence and decay of Cladophora, we investigated the prevalence of antibiotic resistance (ABR) in Cladophora-associated bacterial communities up-gradient and down-gradient from a large sewage treatment plant (STP) on Lake Ontario. Although STPs are well-known sources of ABR, we also expected detectable ABR from up-gradient wetland communities, since they receive surface run-off from urban and agricultural sources. Statistically significant differences in aquatic bacterial abundance and ABR were found between down-gradient beach samples and up-gradient coastal wetland samples (ANOVA, Holm-Sidak test, p < 0.05). Decaying and free-floating Cladophora sampled near the STP had the highest bacterial densities overall, including on ampicillin- and vancomycin-treated plates. However, quantitative polymerase chain reaction analysis of the ABR genes ampC, tetA, tetB, and vanA from environmental communities showed a different pattern. Some of the highest ABR gene levels occurred at the 2 coastal wetland sites (vanA). Overall, bacterial ABR profiles from environmental samples were distinguishable between living and decaying Cladophora, inferring that Cladophora may control bacterial ABR depending on its life-cycle stage. Our results also show how spatially and temporally dynamic ABR is in nearshore aquatic bacteria, which warrants further research.

Field Evaluation of the Restorative Capacity of the Aquifer Downgradient of a Uranium In-Situ Recovery Mining Site

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reimus, Paul William

A two-part field study was conducted in Smith Ranch-Highland in-situ recovery (ISR) near Douglas, Wyoming, to evaluate the restorative capacity of the aquifer downgradient (i.e., hydrologically downstream) of a Uranium ISR mining site with respect to the transport of uranium and other potential contaminants in groundwater after mining has ceased. The study was partially conducted by checking the Uranium content and the alkalinity of separate wells, some wells had been restored and others had not. A map and in-depth procedures of the study are included.

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

PubMed

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

2008-11-14

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 evaluated using numerical modeling. At this site, the TCE DNAPL zone formed decades ago, and was hydraulically isolated by means of an innovative system performing groundwater extraction, treatment and re-injection. Treated water is re-injected in a row of injection wells situated a short distance downgradient of the extraction wells, creating a clean-water displacement front to efficiently flush the downgradient plume. This scheme avoids the creation of stagnation zones typical of most groundwater pump-and-treat systems, thereby minimizing the time for aquifer flushing and therefore downgradient cleanup. The system began operation in August 2002 and although the performance monitoring shows substantial declines in concentrations, detectable levels of TCE and degradation products persist downgradient of the re-injection wells, long after the TCE should have disappeared based on calculations assuming a nearly homogenous sand aquifer. Three hypotheses were assessed for this plume persistence: 1) incomplete source-zone capture, 2) DNAPL occurrence downgradient of the re-injection wells, and 3) back diffusion from one or more thin clay beds in the aquifer. After careful consideration, the first two hypotheses were eliminated, leaving back diffusion as the only plausible hypothesis, supported by detailed measurements of VOC concentrations within and near the clay beds and also by numerical model simulations that closely represent the field site hydrogeologic conditions. The model was also used to simulate a more generalized, hypothetical situation where more thin clayey beds occur in a sand aquifer with an underlying aquitard. While there is no doubt that DNAPL source mass reduction can eventually improve downgradient groundwater quality, the magnitude and time scale over which the improvement occurs is the major uncertainty given current characterization approaches. This study shows that even one thin clay bed, less than 0.2 m thick, can cause plume persistence due to back diffusion for several years or even decades after the flux from the source is completely isolated. Thin clay beds, which have a large storage capacity for dissolved and sorbed contaminant mass, are common in many types of sandy aquifers. However, without careful inspection of continuous cores and sampling, such thin clay beds, and their potential for causing long-term back-diffusion effects, can easily go unnoticed during site characterization.

Buffer zone monitoring plan for the Dos Rios subdivision, Gunnison, Colorado

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

1996-02-01

This report presents a plan for water quality monitoring at the Dos Rios subdivision (Units 2, 3, and the Island Unit) that is intended to satisfy the informational needs of residents who live southwest (downgradient) of the former Gunnison processing site. Water quality monitoring activities described in this report are designed to protect the public from residual contamination that entered the ground water as a result of previous uranium milling operations. Requirements presented in this monitoring plan are also included in the water sampling and analysis plan (WSAP) for the Gunnison Uranium Mill Tailings Remedial Action (UMTRA) Project site. Themore » Gunnison WSAP is a site-specific document prepared by the U.S. Department of Energy (DOE) that provides background, guidance, and justification for future ground water sampling and analysis activities for the UMTRA Project Gunnison processing and disposal sites. The WSAP will be updated annually, as additional water quality data are collected and interpreted, to provide ongoing protection for public health and the environment.« less

Microbial characterization of nitrification in a shallow, nitrogen-contaminated aquifer, Cape Cod, Massachusetts and detection of a novel cluster associated with nitrifying Betaproteobacteria

USGS Publications Warehouse

Miller, D.N.; Smith, R.L.

2009-01-01

Groundwater nitrification is a poorly characterized process affecting the speciation and transport of nitrogen. Cores from two sites in a plume of contamination were examined using culture-based and molecular techniques targeting nitrification processes. The first site, located beneath a sewage effluent infiltration bed, received treated effluent containing O2 (> 300????M) and NH4+ (51-800????M). The second site was 2.5??km down-gradient near the leading edge of the ammonium zone within the contaminant plume and featured vertical gradients of O2, NH4+, and NO3- (0-300, 0-500, and 100-200????M with depth, respectively). Ammonia- and nitrite-oxidizers enumerated by the culture-based MPN method were low in abundance at both sites (1.8 to 350??g- 1 and 33 to 35,000??g- 1, respectively). Potential nitrifying activity measured in core material in the laboratory was also very low, requiring several weeks for products to accumulate. Molecular analysis of aquifer DNA (nested PCR followed by cloning and 16S rDNA sequencing) detected primarily sequences associated with the Nitrosospira genus throughout the cores at the down-gradient site and a smaller proportion from the Nitrosomonas genus in the deeper anoxic, NH4+ zone at the down-gradient site. Only a single Nitrosospira sequence was detected beneath the infiltration bed. Furthermore, the majority of Nitrosospira-associated sequences represent an unrecognized cluster. We conclude that an uncharacterized group associated with Nitrosospira dominate at the geochemically stable, down-gradient site, but found little evidence for Betaproteobacteria nitrifiers beneath the infiltration beds where geochemical conditions were more variable.

Isotopic evidence for reductive immobilization of uranium across a roll-front mineral deposit

DOE PAGES

Brown, Shaun T.; Basu, Anirban; Christensen, John N.; ...

2016-05-20

We use uranium (U) isotope ratios to detect and quantify the extent of natural U reduction in groundwater across a roll front redox gradient. Our study was conducted at the Smith Ranch-Highland in situ recovery (ISR) U mine in eastern Wyoming, USA, where economic U deposits occur in the Paleocene Fort Union formation. To evaluate the fate of aqueous U in and adjacent to the ore body, we investigated the chemical composition and isotope ratios of groundwater samples from the roll-front type ore body and surrounding monitoring wells of a previously mined area. The 238U/ 235U of groundwater varies bymore » approximately 3‰ and is correlated with U concentrations. Fluid samples down-gradient of the ore zone are the most depleted in 238U and have the lowest U concentrations. Activity ratios of 234U/ 238U are ~5.5 up-gradient of the ore zone, ~1.0 in the ore zone, and between 2.3 and 3.7 in the down-gradient monitoring wells. High-precision measurements of 234U/ 238U and 238U/ 235U allow for development of a conceptual model that evaluates both the migration of U from the ore body and the extent of natural attenuation due to reduction. We find that the premining migration of U down-gradient of the delineated ore body is minimal along eight transects due to reduction in or adjacent to the ore body, whereas two other transects show little or no sign of reduction in the down-gradient region. Lastly, these results suggest that characterization of U isotopic ratios at the mine planning stage, in conjunction with routine geochemical analyses, can be used to identify where more or less postmining remediation will be necessary.« less

Evaluation of the fate and transport of chlorinated ethenes in a complex groundwater system discharging to a stream in Wonju, Korea

NASA Astrophysics Data System (ADS)

Lee, Seong-Sun; Kaown, Dugin; Lee, Kang-Kun

2015-11-01

Chlorinated ethenes such as trichloroethylene (TCE) are common and persistent groundwater contaminants. If contaminated groundwater discharges to a stream, then stream water pollution near the contamination site also becomes a problem. In this respect, the fate and transport of chlorinated ethenes around a stream in an industrial complex were evaluated using the concentration of each component, and hydrogeochemical, microbial, and compound-specific carbon isotope data. Temporal and spatial monitoring reveal that a TCE plume originating from main and local source zones continues to be discharged to a stream. Groundwater geochemical data indicate that aerobic conditions prevail in the upgradient area of the studied aquifer, whereas conditions become anaerobic in the downgradient. The TCE molar fraction is high at the main and local source zones, ranging from 87.4 to 99.2% of the total volatile organic compounds (VOCs). An increasing trend in the molar fraction of cis-1, 2-Dichloroethene (cis-DCE) and vinyl chloride (VC) was observed in the downgradient zone of the study area. The enriched δ13C values of TCE and depleted values of cis-DCE in the stream zone, compared to those of the source zone, also suggest biodegradation of VOCs. Microbial community structures in monitoring wells adjacent to the stream zone in the downgradient area were analyzed using 16S rRNA gene-based pyrosequencing to identify the microorganisms responsible for biodegradation. This was attributed to the high relative abundance of dechlorinating bacteria in monitoring wells under anaerobic conditions farthest from the stream in the downgradient area. The multilateral approaches adopted in this study, combining hydrogeochemical and biomolecular methods with compound-specific analyses, indicate that contaminants around the stream were naturally attenuated by active anaerobic biotransformation processes.

Microbial characterization of nitrification in a shallow, nitrogen-contaminated aquifer, Cape Cod, Massachusetts and detection of a novel cluster associated with nitrifying Betaproteobacteria

NASA Astrophysics Data System (ADS)

Miller, Daniel N.; Smith, Richard L.

2009-01-01

Groundwater nitrification is a poorly characterized process affecting the speciation and transport of nitrogen. Cores from two sites in a plume of contamination were examined using culture-based and molecular techniques targeting nitrification processes. The first site, located beneath a sewage effluent infiltration bed, received treated effluent containing O 2 (> 300 µM) and NH 4+ (51-800 µM). The second site was 2.5 km down-gradient near the leading edge of the ammonium zone within the contaminant plume and featured vertical gradients of O 2, NH 4+, and NO 3- (0-300, 0-500, and 100-200 µM with depth, respectively). Ammonia- and nitrite-oxidizers enumerated by the culture-based MPN method were low in abundance at both sites (1.8 to 350 g - 1 and 33 to 35,000 g - 1 , respectively). Potential nitrifying activity measured in core material in the laboratory was also very low, requiring several weeks for products to accumulate. Molecular analysis of aquifer DNA (nested PCR followed by cloning and 16S rDNA sequencing) detected primarily sequences associated with the Nitrosospira genus throughout the cores at the down-gradient site and a smaller proportion from the Nitrosomonas genus in the deeper anoxic, NH 4+ zone at the down-gradient site. Only a single Nitrosospira sequence was detected beneath the infiltration bed. Furthermore, the majority of Nitrosospira-associated sequences represent an unrecognized cluster. We conclude that an uncharacterized group associated with Nitrosospira dominate at the geochemically stable, down-gradient site, but found little evidence for Betaproteobacteria nitrifiers beneath the infiltration beds where geochemical conditions were more variable.

Permeable Asphalt: A New Tool to Reduce Road Salt Contamination of Groundwater in Urban Areas.

PubMed

Dietz, Michael E; Angel, Derek R; Robbins, Gary A; McNaboe, Lukas A

2017-03-01

Chloride contamination of groundwater in urban areas due to deicing is a well-documented phenomenon in northern climates. The objective of this study was to evaluate the effects of permeable pavement on degraded urban groundwater. Although low impact development practices have been shown to improve stormwater quality, no infiltration practice has been found to prevent road salt chlorides from entering groundwater. The few studies that have investigated chlorides in permeable asphalt have involved sampling directly beneath the asphalt; no research has looked more broadly at surrounding groundwater conditions. Monitoring wells were installed upgradient and downgradient of an 860 m 2 permeable asphalt parking lot at the University of Connecticut (Storrs, Connecticut). Water level and specific conductance were measured continuously, and biweekly samples were analyzed for chloride. Samples were also analyzed for sodium (Na), calcium (Ca), and magnesium (Mg). Analysis of variance analysis indicated a significantly (p < 0.001) lower geometric mean Cl concentration downgradient (303.7 mg/L) as compared to upgradient (1280 mg/L). Concentrations of all alkali metals increased upgradient and downgradient during the winter months as compared to nonwinter months, indicating that cation exchange likely occurred. Despite the frequent high peaks of chloride in the winter months as well as the increases in alkali metals observed, monitoring revealed lower Cl concentrations downgradient than upgradient for the majority of the year. These results suggest that the use of permeable asphalt in impacted urban environments with high ambient chloride concentrations can be beneficial to shallow groundwater quality, although these results may not be generalizable to areas with low ambient chloride concentrations. © 2016, National Ground Water Association.

Chemical Evolution of Groundwater Near a Sinkhole Lake, Northern Florida: 2. Chemical Patterns, Mass Transfer Modeling, and Rates of Mass Transfer Reactions

NASA Astrophysics Data System (ADS)

Katz, Brian G.; Plummer, L. Niel; Busenberg, Eurybiades; Revesz, Kinga M.; Jones, Blair F.; Lee, Terrie M.

1995-06-01

Chemical patterns along evolutionary groundwater flow paths in silicate and carbonate aquifers were interpreted using solute tracers, carbon and sulfur isotopes, and mass balance reaction modeling for a complex hydrologic system involving groundwater inflow to and outflow from a sinkhole lake in northern Florida. Rates of dominant reactions along defined flow paths were estimated from modeled mass transfer and ages obtained from CFC-modeled recharge dates. Groundwater upgradient from Lake Barco remains oxic as it moves downward, reacting with silicate minerals in a system open to carbon dioxide (CO2), producing only small increases in dissolved species. Beneath and downgradient of Lake Barco the oxic groundwater mixes with lake water leakage in a highly reducing, silicate-carbonate mineral environment. A mixing model, developed for anoxic groundwater downgradient from the lake, accounted for the observed chemical and isotopic composition by combining different proportions of lake water leakage and infiltrating meteoric water. The evolution of major ion chemistry and the 13C isotopic composition of dissolved carbon species in groundwater downgradient from the lake can be explained by the aerobic oxidation of organic matter in the lake, anaerobic microbial oxidation of organic carbon, and incongruent dissolution of smectite minerals to kaolinite. The dominant process for the generation of methane was by the CO2 reduction pathway based on the isotopic composition of hydrogen (δ2H(CH4) = -186 to -234‰) and carbon (δ13C(CH4) = -65.7 to -72.3‰). Rates of microbial metabolism of organic matter, estimated from the mass transfer reaction models, ranged from 0.0047 to 0.039 mmol L-1 yr-1 for groundwater downgradient from the lake.

Hydrogeology and soil gas at J-Field, Aberdeen Proving Ground, Maryland

USGS Publications Warehouse

Hughes, W.B.

1993-01-01

Disposal of chemical warfare agents, munitions, and industrial chemicals in J-Field, Aberdeen Proving Ground, Maryland, has contaminated soil, groundwater and surface water. Seven exploratory borings and 38 observation wells were drilled to define the hydrogeologic framework at J-Field and to determine the type, extent, and movement of contaminants. The geologic units beneath J-Field consist of Coastal Plain sediments of the Cretaceous Patapsco Formation and Pleistocene Talbot Formation. The Patapsco Formation contains several laterally discontinuous aquifers and confining units. The Pleistocene deposits were divided into 3 hydrogeologic units--a surficial aquifer, a confining unit, and a confined aquifer. Water in the surficial aquifer flows laterally from topographically high areas to discharge areas in marshes and streams, and vertically to the underlying confined aquifer. In offshore areas, water flows from the deeper confined aquifers upward toward discharge areas in the Gunpowder River and Chesapeake Bay. Analyses of soil-gas samples showed high relative-flux values of chlorinated solvents, phthalates, and hydrocarbons at the toxic-materials disposal area, white-phosphorus disposal area, and riot-control-agent disposal area. The highest flux values were located downgradient of the toxic materials and white phosphorus disposal areas, indicating that groundwater contaminants are moving from source areas beneath the disposal pits toward discharge points in the marshes and estuaries. Elevated relative-flux values were measured upgradient and downgradient of the riot-control agent disposal area, and possibly result from soil and (or) groundwater contamination.

Degradation of phenolic contaminants in ground water by anaerobic bacteria: St. Louis Park, Minnesota

USGS Publications Warehouse

Ehrlich, G.G.; Goerlitz, D.F.; Godsy, E.M.; Hult, M.F.

1982-01-01

Coal-tar derivatives from a coal-tar distillation and wood-treating plant that operated from 1918 to 1972 at St. Louis Park, Minnesota contaminated the near-surface ground water. Solutions of phenolic compounds and a water-immiscible mixture of polynuclear aromatic compounds accumulated in wetlands near the plant site and entered the aquifer. The concentration of phenolic compounds in the aqueous phase under the wetlands is about 30 mg/1 but decreases to less than 0.2 mg/1 at a distance of 430 m immediately downgradient from the source. Concentrations of naphthalene (the predominant polynuclear compound in the ground water) and sodium (selected as a conservative tracer) range from about 20 mg/1 and 430 mg/1 in the aqueous phase at the source to about 2 mg/1 and 120 mg/1 at 430 m downgradient, respectively. Phenolic compounds and naphthalene are disappearing faster than expected if only dilution were occurring. Sorption of phenolic compounds on aquifer sediments is negligible but naphthalene is slightly sorbed. Anaerobic biodegradation of phenolic compounds is primarily responsible for the observed attenuation. Methane was found only in water samples from the contaminated zone (2-20 mg/1). Methane-producing bacteria were found only in water from the contaminated zone. Methane was produced in laboratory cultures of contaminated water inoculated with bacteria from the contaminated zone. Evidence for anaerobic biodegradation of naphthalene under either field or laboratory conditions was not obtained.

EXEIS Expert Screening and Optimal Extraction/Injection Pumping Systems for Short-Term Plume Immobilization

DTIC Science & Technology

1990-05-01

TT) d head at observation well j which is down-gradient of the contamination source at the end of the modeling period TT, (L). h head at contaminant...period t, (L); =h 1 ,0 i,t h U = upper limit on head at pump i, (L); (h jTT) d = head at each observation well j which is down-gradient of...E) E D.i j k qt k 1 . . (30)f~q = r~~t ~ I I , j ,k qt-k+l.................(0 i=1 k=1 where: D . - ~ ~ [ft(Qo)A i ,kS dt + fs(Qo)P i j ,k’ dS

Delineation and hydrologic effects of a gasoline leak at Stovepipe Wells Hotel, Death Valley National Monument, California

USGS Publications Warehouse

Buono, A.; Packard, Elaine M.

1982-01-01

Ground water is the only local source of water available to the Stovepipe Wells Hotel facilities of the Death Valley National Monument, California. A leak in a service station storage tank caused the formation of a gasoline layer overlying the water table, creating the potential for contamination of the water supply. The maximum horizontal extent of the gasoline layer was mathematically estimated to be 1,300 feet downgradient from the leaky gasoline tank. Exploratory drilling detected the gasoline layer between 900 and 1,400 feet downgradient and between 50 and 150 feet upgradient from the source. Traces of the soluble components of gasoline were also found in the aquifer 150 feet upgradient, and 250 feet distant from the source perpendicular to the direction of ground-water movement. The gasoline spill is not likely to have an effect on the supply wells located 0.4 mile south of the leak source, which is nearly perpendicular to the direction of ground-water movement and the primary direction of gasoline movement in the area. No effect on phreatophytes 2 miles downgradient from the layer is likely, but the potential effects of gasoline vapors within the unsaturated zone on local xerophytes are not known. (USGS)

Groundwater quality impacts from the land application of treated municipal wastewater in a large karstic spring basin: Chemical and microbiological indicators

USGS Publications Warehouse

Katz, B.G.; Griffin, Dale W.; Davis, J.H.

2009-01-01

Geochemical and microbiological techniques were used to assess water-quality impacts from the land application of treated municipal wastewater in the karstic Wakulla Springs basin in northern Florida. Nitrate-N concentrations have increased from about 0.2 to as high as 1.1??mg/L (milligrams per liter) during the past 30??years in Wakulla Springs, a regional discharge point for groundwater (mean flow about 11.3??m3/s) from the Upper Floridan aquifer (UFA). A major source of nitrate to the UFA is the approximately 64??million L/d (liters per day) of treated municipal wastewater applied at a 774??ha (hectare) sprayfield farming operation. About 260 chemical and microbiological indicators were analyzed in water samples from the sprayfield effluent reservoir, wells upgradient from the sprayfield, and from 21 downgradient wells and springs to assess the movement of contaminants into the UFA. Concentrations of nitrate-N, boron, chloride, were elevated in water samples from the sprayfield effluent reservoir and in monitoring wells at the sprayfield boundary. Mixing of sprayfield effluent water was indicated by a systematic decrease in concentrations of these constituents with distance downgradient from the sprayfield, with about a 10-fold dilution at Wakulla Springs, about 15??km (kilometers) downgradient from the sprayfield. Groundwater with elevated chloride and boron concentrations in wells downgradient from the sprayfield and in Wakulla Springs had similar nitrate isotopic signatures, whereas the nitrate isotopic composition of water from other sites was consistent with inorganic fertilizers or denitrification. The sprayfield operation was highly effective in removing most studied organic wastewater and pharmaceutical compounds and microbial indicators. Carbamazepine (an anti-convulsant drug) was the only pharmaceutical compound detected in groundwater from two sprayfield monitoring wells (1-2??ppt). One other detection of carbamazepine was found in a distant well water sample where enteroviruses also were detected, indicating a likely influence from a nearby septic tank.

Evaluation of the fate and transport of chlorinated ethenes in a complex groundwater system discharging to a stream in Wonju, Korea.

PubMed

Lee, Seong-Sun; Kaown, Dugin; Lee, Kang-Kun

2015-11-01

Chlorinated ethenes such as trichloroethylene (TCE) are common and persistent groundwater contaminants. If contaminated groundwater discharges to a stream, then stream water pollution near the contamination site also becomes a problem. In this respect, the fate and transport of chlorinated ethenes around a stream in an industrial complex were evaluated using the concentration of each component, and hydrogeochemical, microbial, and compound-specific carbon isotope data. Temporal and spatial monitoring reveal that a TCE plume originating from main and local source zones continues to be discharged to a stream. Groundwater geochemical data indicate that aerobic conditions prevail in the upgradient area of the studied aquifer, whereas conditions become anaerobic in the downgradient. The TCE molar fraction is high at the main and local source zones, ranging from 87.4 to 99.2% of the total volatile organic compounds (VOCs). An increasing trend in the molar fraction of cis-1, 2-Dichloroethene (cis-DCE) and vinyl chloride (VC) was observed in the downgradient zone of the study area. The enriched δ(13)C values of TCE and depleted values of cis-DCE in the stream zone, compared to those of the source zone, also suggest biodegradation of VOCs. Microbial community structures in monitoring wells adjacent to the stream zone in the downgradient area were analyzed using 16S rRNA gene-based pyrosequencing to identify the microorganisms responsible for biodegradation. This was attributed to the high relative abundance of dechlorinating bacteria in monitoring wells under anaerobic conditions farthest from the stream in the downgradient area. The multilateral approaches adopted in this study, combining hydrogeochemical and biomolecular methods with compound-specific analyses, indicate that contaminants around the stream were naturally attenuated by active anaerobic biotransformation processes. Copyright © 2015 Elsevier B.V. All rights reserved.

Modern marine sediments as a natural analog to the chemically stressed environment of a landfill

USGS Publications Warehouse

Baedecker, M.J.; Back, W.

1979-01-01

Chemical reactions that occur in landfills are analogous to those reactions that occur in marine sediments. Lateral zonation of C, N, S, O, H, Fe and Mn species in landfills is similar to the vertical zonation of these species in marine sediments and results from the following reaction sequence: (1) oxidation of C, N and S species in the presence of dissolved free oxygen to HCO3-, NO3- and SO2-4; (2) after consumption of molecular oxygen, then NO3- is reduced, and Fe and Mn are solubilized; (3) SO2-4 is reduced to sulfide; and (4) organic compounds become the source of oxygen, and CH4 and NH4+ are formed as fermentation products. In a landfill in Delaware the oxidation potential increases downgradient and the redox zones in the reducing plume are characterized by: CH4, NH4+, Fe2+. Mn2+, HCO3- and NO3-. Lack of SO2-4 at that landfill eliminates the sulfide zone. Although it has not been observed at landfills, mineral alteration should result in precipitation of pyrite and/or siderite downgradient. Controls on the pH of leachate are the relative rates of production of HCO3-, NH4+ and CH4. Production of methane by fermentation at landfills results in 13C isotope fractionation and the accumulation of isotopically heavy ??CO2 (+10 to +18??? PDB). Isotope measurements may be useful to determine the extent of CO2 reduction in landfills and extent of dilution downgradient. The boundaries of reaction zones in stressed aquifers are determined by head distribution and flow velocity. Thus, if the groundwater flow is rapid relative to reaction rates, redox zones will develop downgradient. Where groundwater flow velocities are low the zones will overlap to the extent that they may be indeterminate. ?? 1979.

Groundwater quality impacts from the land application of treated municipal wastewater in a large karstic spring basin: chemical and microbiological indicators.

PubMed

Katz, Brian G; Griffin, Dale W; Davis, J Hal

2009-04-01

Geochemical and microbiological techniques were used to assess water-quality impacts from the land application of treated municipal wastewater in the karstic Wakulla Springs basin in northern Florida. Nitrate-N concentrations have increased from about 0.2 to as high as 1.1 mg/L (milligrams per liter) during the past 30 years in Wakulla Springs, a regional discharge point for groundwater (mean flow about 11.3 m(3)/s) from the Upper Floridan aquifer (UFA). A major source of nitrate to the UFA is the approximately 64 million L/d (liters per day) of treated municipal wastewater applied at a 774 ha (hectare) sprayfield farming operation. About 260 chemical and microbiological indicators were analyzed in water samples from the sprayfield effluent reservoir, wells upgradient from the sprayfield, and from 21 downgradient wells and springs to assess the movement of contaminants into the UFA. Concentrations of nitrate-N, boron, chloride, were elevated in water samples from the sprayfield effluent reservoir and in monitoring wells at the sprayfield boundary. Mixing of sprayfield effluent water was indicated by a systematic decrease in concentrations of these constituents with distance downgradient from the sprayfield, with about a 10-fold dilution at Wakulla Springs, about 15 km (kilometers) downgradient from the sprayfield. Groundwater with elevated chloride and boron concentrations in wells downgradient from the sprayfield and in Wakulla Springs had similar nitrate isotopic signatures, whereas the nitrate isotopic composition of water from other sites was consistent with inorganic fertilizers or denitrification. The sprayfield operation was highly effective in removing most studied organic wastewater and pharmaceutical compounds and microbial indicators. Carbamazepine (an anti-convulsant drug) was the only pharmaceutical compound detected in groundwater from two sprayfield monitoring wells (1-2 ppt). One other detection of carbamazepine was found in a distant well water sample where enteroviruses also were detected, indicating a likely influence from a nearby septic tank.

Hydrogeologic and water-quality data from well clusters near the wastewater-treatment plant, U.S. Marine Corps Air Station, Cherry Point, North Carolina

USGS Publications Warehouse

Murray, L.C.; Daniel, C. C.

1990-01-01

Hydrogeologic and ground-water quality data were collected near the wastewater-treatment plant and associated polishing lagoons at the Marine Corps Air Station, Cherry Point, North Carolina, in 1988. Between March and May 1988, two observation wells were installed upgradient and six wells were installed downgradient of the polishing lagoons and sampled for organic and inorganic U.S. Environmental Protection Agency priority pollutants. Placement of the well screens allowed sampling from both the upper and lower parts of the surficial aquifer. Natural gamma-ray geophysical logs were run in the four deepest wells. Lithologic logs were prepared from split-spoon samples collected during the drilling operations. Laboratory hydraulic conductivity tests were conducted on samples of fine-grained material recovered from the two confining units that separate the surficial aquifer and the drinking-water supply aquifer; values ranged from 0.011 to 0.014 foot per day (4x10-6 to 5x10-6 centimeters per second). Static water levels were recorded on April 25, 1988. Relatively low concentrations of purgeable organic compounds (up to 2.2 micrograms per liter for dichlorodifluoromethane), acid and base/neutral extractable compounds (up to 58 micrograms per liter for bis(2-ethylhexyl) phthalate), or pesticides (up to 0.03 micrograms per liter for diazinon and methyl parathion) were detected in water samples collected from all of the wells. Trace metals were detected in concentrations above minimum detectable limits in all of the wells and were found to be higher in water samples collected from the downgradient wells (up to 320 micrograms per liter for zinc) than in water samples from the upgradient wells.

Phenolic contamination in the sand-and-gravel aquifer from a surface impoundment of wood treatment wastes, Pensacola, Florida

USGS Publications Warehouse

Troutman, D.E.; Godsy, E.M.; Goerlitz, D.F.; Ehrlich, G.G.

1984-01-01

Creosote and pentachlorophenol wastewaters discharged to unlined surface impoundments have resulted in groundwater contamination in the vicinity of an industrial site near Pensacola, Florida. Total phenol concentrations of 36,000 microgm/liter have been detected 40 ft below land surface in a test hole 100 ft south of an overflow impoundment but less than 10 microgm/liter 90 ft below land surface. Samples collected in test holes 1,350 ft downgradient from the surface impoundments and 100 ft north of Pensacola Bay, above and immediately below a clay lens, indicate that phenol contaminated groundwater may not be discharging directly into Pensacola Bay. Phenol concentrations exceeding 20 microgm/liter were detected in samples from a drainage ditch discharging directly into Bayou Chico. Microbiological data collected near the test site suggest that an anaerobic methanogenic ecosystem contributes to a reduction in phenol concentrations in groundwater. A laboratory study using bacteria isolated from the study site indicates that phenol, 2-methylphenol, and 3-methylphenol are significantly degraded and that methanogenesis reduces total phenol concentrations in laboratory digestors by 45%. Pentachlorophenol may inhibit methanogenesis at concentrations exceeding 0.45 milligm/liter. (USGS)

Effects of a remedial system and its operation on volatile organic compound-contaminated ground water, Operable Unit 1, Savage Municipal Well Superfund Site, Milford, New Hampshire, 1998-2004

USGS Publications Warehouse

Harte, Philip T.

2006-01-01

The Savage Municipal Well Superfund site in the Town of Milford, N.H., is underlain by a 0.5-square mile plume of volatile organic compounds (VOCs), mostly tetrachloroethylene (PCE). The plume occurs mostly within a highly transmissive sand and gravel layer, but also extends into underlying till and bedrock. The plume has been divided into two areas called Operable Unit 1 (OU1), which contains the primary source area, and Operable Unit 2 (OU2), which is defined as the extended plume area. PCE concentrations in excess of 100,000 parts per billion (ppb) had been detected in the OU1 area in 1995, indicating a likely Dense Non-Aqueous Phase Liquid (DNAPL) source. In the fall of 1998, the New Hampshire Department of Environmental Services (NHDES) and the U.S. Environmental Protection Agency (USEPA) installed a remedial system in OU1 to contain and capture the dissolved VOC plume. The OU1 remedial system includes a low-permeability barrier wall that encircles the highest detected concentrations of PCE, and a series of injection and extraction wells to contain and remove contaminants. The barrier wall likely penetrates the full thickness of the sand and gravel; in most places, it also penetrates the full thickness of the underlying basal till and sits atop bedrock. Remedial injection and extraction wells have been operating since the spring of 1999 and include a series of interior (inside the barrier wall) injection and extractions wells and exterior (outside the barrier wall) injection and extraction wells. A recharge gallery outside the barrier wall receives the bulk of the treated water and reinjects it into the shallow aquifer. From 1998 to 2004, PCE concentrations decreased by an average of 80 percent at most wells outside the barrier wall. This decrease indicates (1) the barrier wall and interior extraction effectively contained high PCE concentrations inside the wall, (2) other sources of PCE did not appear to be outside of the wall, and (3) ambient ground-water flow in conjunction with the exterior remedial wells effectively remediated most of the dissolved PCE plume outside the wall. The overburden at middle depths (40 to 70 ft below land surface) downgradient from exterior extraction wells showed relatively slow decreases in PCE concentrations compared to other areas outside the barrier wall. Numerical simulation shows extraction caused the formation of a small downgradient slow-velocity zone. Because the ambient ground-water velocities are high (approximately 1 foot per day), temporary termination of extraction at the exterior wells may increase dilution downgradient from the exterior extraction wells. Extraction can also be optimized on the basis of seasonal hydrologic conditions to facilitate exterior well capture from upgradient areas outside of the barrier wall where PCE concentrations are highest. Reductions in concentrations of PCE inside the barrier wall from 1998 to 2003 were minimal near suspected source areas, indicating that the operation of interior remedial wells had not been effective in remediating dissolved PCE or the DNAPL source. Capture of the dissolved PCE plume within the barrier wall by interior extraction wells could be enhanced if operation (injection rates) increased at underutilized interior injection wells, thereby increasing hydraulic gradients.

Source, Distribution, and Management of Arsenic in Water from Wells, Eastern San Joaquin Ground-Water Subbasin, California

USGS Publications Warehouse

Izbicki, John A.; Stamos, Christina L.; Metzger, Loren F.; Halford, Keith J.; Kulp, Thomas R.; Bennett, George L.

2008-01-01

Between 1974 and 2001 water from as many as one-third of wells in the Eastern San Joaquin Ground Water Subbasin, about 80 miles east of San Francisco, had arsenic concentrations greater than the U.S. Environmental Protection Agency Maximum Contaminant Level (MCL) for arsenic of 10 micrograms per liter (ug/L). Water from some wells had arsenic concentrations greater than 60 ug/L. The sources of arsenic in the study area include (1) weathering of arsenic bearing minerals, (2) desorption of arsenic associated with iron and manganese oxide coatings on the surfaces of mineral grains at pH's greater than 7.6, and (3) release of arsenic through reductive dissolution of iron and manganese oxide coatings in the absence of oxygen. Reductive dissolution is responsible for arsenic concentrations greater than the MCL. The distribution of arsenic varied areally and with depth. Concentrations were lower near ground-water recharge areas along the foothills of the Sierra Nevada; whereas, concentrations were higher in deeper wells at the downgradient end of long flow paths near the margin of the San Joaquin Delta (fig. 1). Management opportunities to control high arsenic concentrations are present because water from the surface discharge of wells is a mixture of water from the different depths penetrated by wells. On the basis of well-bore flow and depth-dependent water-quality data collected as part of this study, the screened interval of a public-supply well having arsenic concentrations that occasionally exceed the MCL was modified to reduce arsenic concentrations in the surface discharge of the well. Arsenic concentrations from the modified well were about 7 ug/L. Simulations of ground-water flow to the well showed that although upward movement of high-arsenic water from depth within the aquifer occurred, arsenic concentrations from the well are expected to remain below the MCL.

Hydrogeology and hydrochemistry of a shallow alluvial aquifer, western Saudi Arabia

NASA Astrophysics Data System (ADS)

Al-Shaibani, Abdulaziz M.

2008-02-01

A hydrogeological and hydrochemical study was conducted on a shallow alluvial aquifer, Wadi Wajj, in western Saudi Arabia to assess the influence of protection measures on groundwater quality. The hydrochemistry was assessed up-gradient and down-gradient from potential contamination sources in the main city in dry and wet seasons prior to and after the installation of major drainage and wastewater facilities. Wadi Wajj is an unconfined aquifer where water is stored and transmitted through fractured and weathered bedrock and the overlying alluvial sediments. Natural recharge to the aquifer is about 5% of rainfall-runoff. Hydrochemistry of the aquifer shows temporal and seasonal changes as influenced by protection measures and rainfall runoff. Both groundwater and runoff showed similar chemical signature, which is mostly of chloride-sulfate-bicarbonate and sodium-calcium type. Groundwater downstream of the city, though of poorer quality than upstream, showed significant improvement after the installation of a concrete runoff tunnel and a wastewater treatment plant. Concentrations of many of the groundwater quality indicators (e.g., TDS, coliform bacteria, and nitrate) exceed US Environmental Protection Agency drinking-water standards. Heavy metal content is, however, within allowable limits by local and international standards. The chemical analyses also suggest the strong influence of stream runoff and sewage water on the groundwater quality.

Effects of effluent spray irrigation on ground water at a test site near Tarpon Springs, Florida

USGS Publications Warehouse

Brown, D.P.

1982-01-01

Secondary-treated effluent was applied to a 7.2-acre test site near Tarpon Springs, Fla., for about 1 year at an average rate of 0.06 million gallons per day and 3 years at 0.11 million gallons per day. Chemical fertilizer was applied periodically to the test site and adjacent areas. Periodic mounding of the water table occurred due to effluent irrigation, inducing radial flow from the test site. Physical, geochemical, biochemical processes effectively reduced total nitrogen concentration 90% and total phosphorous concentration more than 95% in the ground water of the surficial aquifer about 300 feet downgradient from the test site from that of the applied effluent. Downgradient, total nitrogen averaged 2.4 milligrams per liter and total phosphorus averaged 0.17 milligrams per liter. Substantial increases in total phosphorus were observed when the pH of the ground water increased. Total coliform bacteria in the ground water of the surficial aquifer were generally less than 100 colonies per 100 milliliters. Fecal coliform bacteria were generally less than 25 colonies per 100 milliliters at the test site and were not detected downgradient or near the test site. Fecal streptococcal bacteria were generally less than 100 colonies per 100 milliliters at the test site, but were detected on three occasions near the test site. (USGS)

Hydrogeology and trichloroethene contamination in the sea-level aquifer beneath the Logistics Center, Fort Lewis, Washington

USGS Publications Warehouse

Dinicola, Richard S.

2005-01-01

The U.S. Army disposed of waste trichloroethene (TCE) and other materials in the East Gate Disposal Yard near the Logistics Center on Fort Lewis, Washington, from the 1940s to the early 1970s. As a result, ground water contaminated with primarily TCE extends more than 3 miles downgradient from the East Gate Disposal Yard. The site is underlain by a complex and heterogeneous sequence of glacial and non-glacial deposits that have been broadly categorized into an upper and a lower aquifer (the latter referred to as the sea-level aquifer). TCE contamination was detected in both aquifers. This report describes an investigation by the U.S. Geological Survey (USGS) of the source, migration, and attenuation of TCE in the sea-level aquifer. A refined conceptual model for ground-water flow and contaminant migration into and through the sea-level aquifer was developed in large part from interpretation of environmental tracer data. The tracers used included stable isotopes of oxygen (18O), hydrogen (2H), and carbon (13C); the radioactive hydrogen isotope tritium (3H); common ions and redox-related analytes; chlorofluorocarbons; and sulfur hexafluoride. Tracer and TCE concentrations were determined for samples collected by the USGS from 37 wells and two surface-water sites in American Lake during 1999-2000. Ground-water levels were measured by the USGS in more than 40 wells during 2000-01, and were combined with measurements by the U.S. Army and others to create potentiometric-surface maps. Localized ground-water flow features were identified that are of particular relevance to the migration of TCE in the study area. A ridge of ground water beneath American Lake diverts the flow of TCE-contaminated ground water in the sea-level aquifer to the west around the southern end of the lake. Tracer data provided clear evidence that American Lake is a significant source of recharge to the sea-level aquifer that has created that ridge of ground water. High ground-water altitudes at locations north and northeast of the Logistics Center combined with the ridge beneath American Lake prevent TCE contaminated water beneath the Logistics Center from migrating toward municipal water-supply wells northeast of the site. The 1999-2000 TCE concentrations measured by the USGS at older wells screened in the sea-level aquifer were similar to those measured since 1995, but the known downgradient extent of the TCE contamination expanded nearly 2 miles after the Army installed and sampled new wells during 2003-04. Concentrations of TCE in the sea-level aquifer were consistently highest in the upper part of the aquifer throughout the plume, although TCE has spread throughout much of the thickness of the aquifer in the downgradient portions of the plume. Environmental tracer data indicated that the primary pathway for contaminant migration into the sea-level aquifer is through the previously identified confining unit window, an area where the predominately fine-grained confining unit is relatively coarse grained and more permeable. Other less substantial pathways for contaminant migration also were identified near the East Gate Disposal Yard and the I-5 pump-and-treat facilities. Those areas are near active pumping wells and ground-water reintroduction facilities, but there is no evidence that the contaminant migration was caused or enhanced by those activities. Within the sea-level aquifer, TCE concentrations continue to migrate westward in the flow field strongly influenced by ground-water recharge from American Lake. Historical data are not available to definitively determine if the 5-?g/L leading edge of the current TCE plume is stable or if it is still moving downgradient. However, an evaluation of the available data combined with TCE traveltime estimates indicates that the peak TCE concentrations in the sea-level aquifer may have not yet reached the wells near the currently defined leading edge of the plume. Hypothetically, the 5-?g/L leading edge

Evaluation of Elevated Tritium Levels in Groundwater Downgradient from the 618-11 Burial Ground Phase I Investigations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dresel, P.E.; Smith, R.M.; Williams, B.A.

2000-05-01

This report describes the results of the preliminary investigation of elevated tritium in groundwater discovered near the 618-11 burial ground, located in the eastern part of the Hanford Site. Tritium in one well downgradient of the burial ground was detected at levels up to 8,140,000 pCi/L. The 618-11 burial ground received a variety of radioactive waste from the 300 Area between 1962 and 1967. The burial ground covers 3.5 hectare (8.6 acre) and contains trenches, large diameter caissons, and vertical pipe storage units. The burial ground was stabilized with a native sediment covering. The Energy Northwest reactor complex was constructedmore » immediately east of the burial ground.« less

Distribution and mass loss of volatile organic compounds in the surficial aquifer at sites FT03, LF13, and WP14/LF15, Dover Air Force Base, Delaware, November 2000-February 2001

USGS Publications Warehouse

Barbaro, Jeffrey R.; Neupane, Pradumna P.

2002-01-01

Ground-water and surface-water sampling was conducted in the natural attenuation study area in the East Management Unit of Dover Air Force Base, Delaware to determine the distributions of volatile organic compounds in the vicinity of four sites?Fire Training Area Three, the Rubble Area Landfill, the Receiver Station Landfill, and the Liquid Waste Disposal Landfill. This work was done by the U.S. Geological Survey, in cooperation with the U.S. Air Force, as part of an ongoing assessment of the effectiveness of natural attenuation at these sites. The specific objectives of the study were to (1) determine the areal and vertical extent of the contaminant plumes and source areas, (2) measure volatile organic compound concentrations in ground-water discharge areas and in surface water under base-flow conditions, (3) evaluate the potential for off-site migration of the mapped plumes, and (4) estimate the amount of mass loss downgradient of the Liquid Waste Disposal and Receiver Station Landfills. A direct-push drill rig and previously installed multi-level piezometers were used to determine the three-dimensional distributions of volatile organic compounds in the 30?60-foot-thick surficial aquifer underlying the natural attenuation study area. A hand -driven mini-piezometer was used to collect ground-water samples in ground-water discharge areas. A total of 319 ground-water and 4 surface-water samples were collected from November 2000 to February 2001 and analyzed for chlorinated solvents and fuel hydrocarbons. The contaminant plumes migrating from Fire Training Area Three and the Rubble Area Landfill are approximately 500 feet and 800 feet, respectively, in length. These plumes consist predominantly of cis-1,2-dichloroethene, a daughter product, indicating that extensive dechlorination of tetrachloroethene and trichloroethene has occurred at these sites. With an approximate length of 2,200 feet, the plume migrating from the Receiver Station and Liquid Waste Disposal Landfills is the largest of the three plumes in the East Management Unit. In this plume, the parent compounds, tetrachloroethene and trichloroethene, as well as cis-1,2-dichloroethene, are present downgradient of the source. Vinyl chloride was not detected in the natural attenuation study area. Vertical water-quality profiles indicate that volatile organic compounds are present mainly in the upper part of the surficial aquifer. Plumes of fuel hydrocarbon constituents were not detected in the natural attenuation study area. Volatile organic compounds were present at concentrations above detection limits in 6 of 14 samples collected from the aquifer underlying the bed of Pipe Elm Branch and the drainage ditch adjacent to Fire Training Area Three, indicating that the plumes migrating from Fire Training Area Three and the Receiver Station and Liquid Waste Disposal Landfills are reaching these ground-water discharge areas. In contrast, sampling results indicated that the plume from the Rubble Area Landfill does not reach these ground-water discharge areas. Trichloroethene was present above detection limits in one of four surface-water samples collected from Pipe Elm Branch and the drainage ditch adjacent to Fire Training Area Three. The trichloroethene concentration is below applicable Delaware Department of Natural Resources and Environmental Control surface-water-quality standards for human health. An assessment of chlorinated-solvent mass loss in the plume migrating from the Receiver Station and Liquid Waste Disposal Landfills indicates that tetrachloroethene and trichloroethene mass loss downgradient of the source is negligible. Cis-1,2-dichloroethene, however, appears to biodegrade by an unidentified reaction in the plume. Plan-view maps of the plume migrating from the Receiver Station and Liquid Waste Disposal Landfills indicate that tetrachloroethene, trichloroethene, and cis-1,2-dichloroethene may migrate off Dover Air Force Base property approximately 1,500 f

Using analytic element models to delineate drinking water source protection areas.

PubMed

Raymond, Heather A; Bondoc, Michael; McGinnis, John; Metropulos, Kathy; Heider, Pat; Reed, Allison; Saines, Steve

2006-01-01

Since 1999, Ohio EPA hydrogeologists have used two analytic element models (AEMs), the proprietary software GFLOW and U.S. EPA's WhAEM, to delineate protection areas for 535 public water systems. Both models now use the GFLOW2001 solution engine, integrate well with Geographic Information System (GIS) technology, have a user-friendly graphical interface, are capable of simulating a variety of complex hydrogeologic settings, and do not rely upon a model grid. These features simplify the modeling process and enable AEMs to bridge the gap between existing simplistic delineation methods and more complex numerical models. Ohio EPA hydrogeologists demonstrated that WhAEM2000 and GFLOW2000 were capable of producing capture zones similar to more widely accepted models by applying the AEMs to eight sites that had been previously delineated using other methods. After the Ohio EPA delineated protection areas using AEMs, more simplistic delineation methods used by other states (volumetric equation and arbitrary fixed radii) were applied to the same water systems to compare the differences between various methods. GIS software and two-tailed paired t-tests were used to quantify the differences in protection areas and analyze the data. The results of this analysis demonstrate that AEMs typically produce significantly different protection areas than the most simplistic delineation methods, in terms of total area and shape. If the volumetric equation had been used instead of AEMs, Ohio would not have protected 265 km2 of critical upgradient area and would have overprotected 269 km2 of primarily downgradient land. Since an increasing number of land-use restrictions are being tied to drinking water protection areas, this analysis has broad policy implications.

Geohydrologic evaluation of a landfill in a coastal area, St Petersburg, Florida

USGS Publications Warehouse

Hutchinson, C.B.; Stewart, Joseph W.

1978-01-01

The 250-acre Toytown landfill site is in a poorly-drained area in coastal Pinellas County, Florida. Average altitude of land surface at the landfill is less than 10 feet. About 1000 tons of solid waste and about 200,000 gallons of digested sewage sludge are disposed of daily at the landfill. The velocity of ground-water flow through the 23-foot thick surficial aquifer northeast from the landfill toward Old Tampa Bay probably ranges from 1 to 10 feet per year, and downward velocity through the confining bed is about 0.00074 foot per day. The horizontal and vertical flow velocities indicate that leachate moves slowly downgradient, and that leachate has not yet seeped through the confining bed after 12 years of landfill operation. Untreated surface run-off from the site averages about 15 inches per year, and ground-water outflow averages about 3.3 inches per year. The Floridan aquifer is used as a limited source of water for domestic supply in this area. (Woodard-USGS)

Screening tool to evaluate the vulnerability of down-gradient receptors to groundwater contaminants from uncapped landfills

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baker, Ronald J.; Reilly, Timothy J.; Lopez, Anthony

2015-09-15

Highlights: • A spreadsheet-based risk screening tool for groundwater affected by landfills is presented. • Domenico solute transport equations are used to estimate downgradient contaminant concentrations. • Landfills are categorized as presenting high, moderate or low risks. • Analysis of parameter sensitivity and examples of the method’s application are given. • The method has value to regulators and those considering redeveloping closed landfills. - Abstract: A screening tool for quantifying levels of concern for contaminants detected in monitoring wells on or near landfills to down-gradient receptors (streams, wetlands and residential lots) was developed and evaluated. The tool uses Quick Domenicomore » Multi-scenario (QDM), a spreadsheet implementation of Domenico-based solute transport, to estimate concentrations of contaminants reaching receptors under steady-state conditions from a constant-strength source. Unlike most other available Domenico-based model applications, QDM calculates the time for down-gradient contaminant concentrations to approach steady state and appropriate dispersivity values, and allows for up to fifty simulations on a single spreadsheet. Sensitivity of QDM solutions to critical model parameters was quantified. The screening tool uses QDM results to categorize landfills as having high, moderate and low levels of concern, based on contaminant concentrations reaching receptors relative to regulatory concentrations. The application of this tool was demonstrated by assessing levels of concern (as defined by the New Jersey Pinelands Commission) for thirty closed, uncapped landfills in the New Jersey Pinelands National Reserve, using historic water-quality data from monitoring wells on and near landfills and hydraulic parameters from regional flow models. Twelve of these landfills are categorized as having high levels of concern, indicating a need for further assessment. This tool is not a replacement for conventional numerically-based transport model or other available Domenico-based applications, but is suitable for quickly assessing the level of concern posed by a landfill or other contaminant point source before expensive and lengthy monitoring or remediation measures are taken. In addition to quantifying the level of concern using historic groundwater-monitoring data, the tool allows for archiving model scenarios and adding refinements as new data become available.« less

Use of environmental tracers to study the chemical evolution of shallow ground water in a karst area of northern Florida

DOE Office of Scientific and Technical Information (OSTI.GOV)

Katz, B.G.; Plummer, L.N.; Busenberg, E.

1993-03-01

The pathways of shallow ground-water flow in poorly confined aquifer systems of northern FL are influenced by inflow to and outflow from numerous sinkhole lakes that are characteristic of the Sand Hills karst region. Ground-water samples were collected immediately upgradient and downgradient from Lake Barco at depths of 1.6--29 m below the water table from observation wells completed in the surficial aquifer system, the intermediate confining unit (icu), and the Upper Floridan aquifer. Samples were also collected of rainfall, lake water, and ground water at a depth of 4.1 m beneath the lake bottom. The environmental tracers tritium and chlorofluorocarbonsmore » were used to estimate mean residence times of water and rates of chemical mass transfer along flow paths. Water samples collected from wells upgradient of the lake were oxic and had CFC-model recharge dates between 1971 and 1986. The content of delta H-2 and delta O-18 of water from the two aquifer systems and the icu was nearly identical to the isotopic composition of rainfall. Changes in the chemical composition of the ground water with depth were simulated by reacting rainfall with minerals and dissolved gases that exist in the hydrogeologic units. Ground-water samples collected from sites beneath and downgradient of the lake were anoxic, with measured concentrations of hydrogen sulfide and methane ranging from 0.02--0.58 mg/l and 0.30--6.1 mg/l, respectively. CFC-model recharge dates ranged from 1956 to 1983. The data indicated that ground water downgradient of the lake is being recharged by leakage of lake water. The chemical composition of ground water is influenced by the movement of lake water through reducing, organic-rich sediments accumulated at the bottom. Along the downgradient flow paths, the water chemistry evolves from the composition of lake water and is modified by subsequent reactions including reduction of sulfate and ferric iron, methanogenesis, and dissolution and precipitation of minerals.« less

Fate of herbicides in a shallow aerobic aquifer: A continuous field injection experiment (Vejen, Denmark)

NASA Astrophysics Data System (ADS)

Broholm, Mette M.; Rügge, Kirsten; Tuxen, Nina; HøJberg, Anker L.; MosbæK, Hans; Bjerg, Poul L.

2001-12-01

A continuous, natural gradient, field injection experiment, involving six herbicides and a tracer, was performed in a shallow aerobic aquifer near Vejen, Denmark. Bentazone, (±)-2-(4-chloro-2-methylphenoxy) propanoic acid (MCPP), dichlorprop, isoproturon, and the dichlobenil metabolite 2,6-dichlor-benzamide (BAM) were injected along with 2-methyl-4,6-dinitrophenol (not discussed in this paper) and the tracer bromide. The injection lasted for 216 days and created a continuous plume in the aquifer. The plume was monitored in three dimensions in 96 multilevel samplers of 6-9 points each for 230 days, with selected individual points for a longer period. The bromide plume followed a complex path through the monitoring network downgradient of the injection wells. The plume movement was controlled by spatially varied hydraulic conductivities of the sand deposit and influenced by asynchronous seasonal variation in groundwater potentials. An average flow velocity of 0.5 m/d was observed, as depicted by bromide. Bentazone, BAM, MCPP, and dichlorprop retardation was negligible, and only slight retardation of isoproturon was observed in the continuous injection experiment and a preceding pulse experiment. No degradation of bentazone was observed in the aerobic aquifer during the monitoring period. BAM and isoproturon were not degraded within 5 m downgradient of the injection. The two phenoxy acids MCPP and dichlorprop were both degraded in the aerobic aquifer. Near the source a lag phase was observed followed by fast degradation of the phenoxy acids, indicating growth kinetics. The phenoxy acids were completely degraded within l m downgradient of the injection wells, resulting in the plumes being divided into small plumes at the injection wells and pulses farther downgradient. During the lag phase, phenoxy acids had spread beyond the 25 m long monitoring network. However, the mass of the phenoxy acids passing the 10-25 m fences never matched the corresponding bentazone or bromide masses, and the pulse was observed to shrink in size. This indicates that this pulse of phenoxy acids was being partially degraded at a low rate as it traveled through the aquifer.

Use of chemical and isotopic tracers to characterize the interactions between ground water and surface water in mantled karst

USGS Publications Warehouse

Katz, B.G.; Coplen, T.B.; Bullen, T.D.; Hal, Davis J.

1997-01-01

In the mantled karst terrane of northern Florida, the water quality of the Upper Floridan aquifer is influenced by the degree of connectivity between the aquifer and the surface. Chemical and isotopic analyses [18O/16O (??18O), 2H/1H (??D), 13C/12C (??13C), tritium(3H), and strontium-87/strontium-86(87Sr/86Sr)]along with geochemical mass-balance modeling were used to identify the dominant hydrochemical processes that control the composition of ground water as it evolves downgradient in two systems. In one system, surface water enters the Upper Floridan aquifer through a sinkhole located in the Northern Highlands physiographic unit. In the other system, surface water enters the aquifer through a sinkhole lake (Lake Bradford) in the Woodville Karst Plain. Differences in the composition of water isotopes (??18O and ??D) in rainfall, ground water, and surface water were used to develop mixing models of surface water (leakage of water to the Upper Floridan aquifer from a sinkhole lake and a sinkhole) and ground water. Using mass-balance calculations, based on differences in ??18O and ??D, the proportion of lake water that mixed with meteoric water ranged from 7 to 86% in water from wells located in close proximity to Lake Bradford. In deeper parts of the Upper Floridan aquifer, water enriched in 18O and D from five of 12 sampled municipal wells indicated that recharge from a sinkhole (1 to 24%) and surface water with an evaporated isotopic signature (2 to 32%) was mixing with ground water. The solute isotopes, ??13C and 87Sr/86Sr, were used to test the sensitivity of binary and ternary mixing models, and to estimate the amount of mass transfer of carbon and other dissolved species in geochemical reactions. In ground water downgradient from Lake Bradford, the dominant processes controlling carbon cycling in ground water were dissolution of carbonate minerals, aerobic degradation of organic matter, and hydrolysis of silicate minerals. In the deeper parts of the Upper Floridan aquifer, the major processes controlling the concentrations of major dissolved species included dissolution of calcite and dolomite, and degradation of organic matter under oxic conditions. The Upper Floridan aquifer is highly susceptible to contamination from activities at the land surface in the Tallahassee area. The presence of post-1950s concentrations of 3H in ground water from depths greater than 100 m below land surface indicates that water throughout much of the Upper Floridan aquifer has been recharged during the last 40 years. Even though mixing is likely between ground water and surface water in many parts of the study area, the Upper Floridan aquifer produces good quality water, which due to dilution effects shows little if any impact from trace elements or nutrients that are present in surface waters.The water quality of the Upper Floridan aquifer is influenced by the degree of connectivity between the aquifer and the surface water. Chemical and isotopic analyses, tritium, and strontium-87/strontium-86 along with geochemical mass-balance modeling were used to identify the dominant hydrochemical processes that control the composition of groundwater. Differences in the composition of water isotopes in rainfall, groundwater and surface water were used to develop mixing models of surface water and groundwater. Even though mixing is likely between groundwater and surface water in many parts of the study area, the Upper Floridan aquifer produces good quality water, showing little impact from trace elements present in surface waters.

DOE Office of Scientific and Technical Information (OSTI.GOV)

LaFreniere, L. M.

Carbon tetrachloride contamination in groundwater at Morrill, Kansas, was initially identified in 1985 during statewide testing of public water supply wells for volatile organic compounds (VOCs). High levels of nitrate were also present in the wells. The city of Morrill is located in Brown County in the northeastern corner of the state, about 7 mi east of Sabetha (Figure 1.1). The population of Morrill as of the 2010 Census was approximately 230 (down from 277 in 2000). All residents of Morrill now obtain their drinking water from the Sabetha municipal water system via a pipeline constructed in 1991. The findingsmore » of the April 2011 and October 2011 monitoring events at Morrill support the following conclusions: (1) Groundwater flow during the 2011 review period (as in prior years) was predominantly to the south, from the vicinity of the former CCC/USDA facility toward Terrapin Creek. Automatic water level monitoring data suggest that spring precipitation and recharge represent the predominant factors affecting the local groundwater level patterns. (2) No significant changes were observed in the concentration or distribution of carbon tetrachloride in groundwater during the spring and fall 2011 monitoring events versus the spring and fall 2010 monitoring events. In October 2011, a maximum carbon tetrachloride concentration of 49 {micro}g/L was identified in groundwater at well MW3S on the former CCC/USDA facility, with concentrations decreasing downgradient toward Terrapin Creek. (3) Since 2004, the accumulated results of 15 sampling events have demonstrated a significant decline in the maximum detected concentration of carbon tetrachloride in groundwater. In 1995, the contaminant was detected at the former CCC/USDA facility at 390 {micro}g/L, while the current maximum levels are < 50 {micro}g/L. The residual contaminant plume extending from the former CCC/USDA facility southward toward Terrapin Creek is well-defined and slowly declining in concentration naturally. (4) No carbon tetrachloride contamination was detected in 2011 in surface waters or shallow streambed sediments sampled at five locations along Terrapin Creek, downgradient from the former CCC/USDA facility. These results indicate that Terrapin Creek remains unaffected by the carbon tetrachloride plume. (5) Since 2007, the accumulated results of 10 monitoring events for surface water and sediment in Terrapin Creek have demonstrated no impact to the sediment and surface waters of the creek by carbon tetrachloride and no imminent risk for further degradation of the creek. (6) Terrapin Creek (tributary segment 308 to Walnut Creek) receives discharge from the Morrill wastewater treatment plant and several confined animal feeding operations regulated by the KDHE. The Walnut Creek watershed is designated by the KDHE as impaired by fecal coliform bacteria. Terrapin Creek is classified by the KDHE as not open to or accessible by the public for contact recreation and does not support the food procurement designated use (KDHE 2010b). (7) In July 2011, trace concentrations of carbon tetrachloride were detected in vegetation samples collected from trees at 2 of the 42 sampled locations south (downgradient) of the former CCC/USDA facility. (8) Sampling of indoor air in August 2010 to evaluate the potential for vapor intrusion into homes overlying and within 100 ft laterally of the identified carbon tetrachloride plume resulted in no detections of carbon tetrachloride. Low concentrations of chloroform, indicative of indoor air sources, were detected. Low radon levels were also detected. The results indicate no evidence of upward migration of vapors from the low-level carbon tetrachloride contamination in groundwater to indoor air.« less

Review of factors affecting recovery of freshwater stored in saline aquifers

USGS Publications Warehouse

Merritt, Michael L.

1989-01-01

A simulation analysis reported previously, and summarized herein, identified the effects of various geohydrologic and operational factors on recoverability of the injected water. Buoyancy stratification, downgradient advection, and hydrodynamic dispersion are the principal natural processes that reduce the amount of injected water that can be recovered. Buoyancy stratification is shown to depend on injection-zone permeability and the density contrast between injected and saline native water. Downgradient advection occurs as a result of natural or induced hydraulic gradients in the aquifer. Hydrodynamic dispersion reduces recovery efficiency by mixing some of the injected water with native saline aquifer water. In computer simulations, the relation of recovery efficiency to volume injected and its improvement during successive injection-recovery cycles was shown to depend on changes in the degree of hydrodynamic dispersion that occurs. Additional aspects of the subject are discussed.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

The Army Creek Landfill (ACL), formerly known as the Llangollen Landfill, is located approximately two miles southwest of New Castle, Delaware, and is adjacent to the Delaware Sand and Gravel Landfill Superfund site. The County operated this 44-acre landfill, which accepted municipal wastes, from 1960 until its closure in 1968 when it was filled to capacity. In late 1971, water in a residential well downgradient of the site developed quality problems. Results from a subsequent investigation showed that leachate, most likely originating from the Army Creek and Delaware Sand and Gravel Landfills, was contaminating local aquifers. This lead to themore » installation of a ground water recovery system designed to maintain a ground water divide between the landfills and the Artesian Water Company Wellfield located downgradient of the landfills. The primary contaminants of concern include: VOCs, inorganics, heavy metals, benzene, and chromium.« less

Effects of a reactive barrier and aquifer geology on metal distribution and mobility in a mine drainage impacted aquifer.

PubMed

Doerr, Nora A; Ptacek, Carol J; Blowes, David W

2005-06-01

The Nickel Rim aquifer has been impacted for five decades by a metal-rich plume generated from the Nickel Rim mine tailings impoundment. Metals released by the oxidation of pyrrhotite in the unsaturated zone of the tailings migrate into the downgradient aquifer, affecting both the groundwater and the aquifer solids. A reactive barrier has been installed in the aquifer to remove sulfate and metals from the groundwater. The effect of the reactive barrier on metal concentrations in the aquifer solids has not previously been studied. In this study, a series of selective extraction procedures was applied to cores of aquifer sediment, to ascertain the distribution of metals among various solid phases present in the aquifer. Extraction results were combined with groundwater chemistry, geochemical modelling and solid-phase microanalyses, to assess the potential mobility of metals under changing geochemical conditions. Reactions within the reactive barrier caused an increase in the solid-phase carbonate content downgradient from the barrier. The concentrations of poorly crystalline, oxidized phases of Mn and Fe, as well as concentrations of Cr(III) associated with oxidized Fe, and poorly crystalline Zn, are lower downgradient from the barrier, whereas total solid-phase metal concentrations remain constant. Iron and Mn accumulate as oxidized, easily extractable forms in a peat layer overlying the aquifer. Although these oxides may buffer reducing plumes, they also have the potential to release metals to the groundwater, should a reduced condition be imposed on the aquifer by remedial actions.

Old groundwater in parts of the upper Patapsco aquifer, Atlantic Coastal Plain, Maryland, USA: Evidence from radiocarbon, chlorine-36 and helium-4

USGS Publications Warehouse

Plummer, Niel; Eggleston, John R.; Raffensperger, Jeff P.; Hunt, Andrew G.; Casile, Gerolamo C.; Andreasen, D.C.

2012-01-01

Apparent groundwater ages along two flow paths in the upper Patapsco aquifer of the Maryland Atlantic Coastal Plain, USA, were estimated using 14C, 36Cl and 4He data. Most of the ages range from modern to about 500 ka, with one sample at 117 km downgradient from the recharge area dated by radiogenic 4He accumulation at more than one Ma. Last glacial maximum (LGM) water was located about 20 km downgradient on the northern flow path, where the radiocarbon age was 21.5 ka, paleorecharge temperatures were 0.5–1.5  °C (a maximum cooling of about 12 °C relative to the modern mean annual temperature of 13 °C), and Cl–, Cl/Br, and stable isotopes of water were minimum. Low recharge temperatures (typically 5–7 °C) indicate that recharge occurred predominantly during glacial periods when coastal heads were lowest due to low sea-level stand. Flow velocities averaged about 1.0 m a–1 in upgradient parts of the upper Patapsco aquifer and decreased from 0.13 to 0.04 m a–1 at 40 and 80 km further downgradient, respectively. This study demonstrates that most water in the upper Patapsco aquifer is non-renewable on human timescales under natural gradients, thus highlighting the importance of effective water-supply management to prolong the resource.

1998 Environmental Monitoring Program Report for the Idaho National Engineering and Environmental Laboratory

DOE Office of Scientific and Technical Information (OSTI.GOV)

L. V. Street

This report describes the calendar year 1998 compliance monitoring and environmental surveillance activities of the Lockheed Martin Idaho Technologies Company Environmental Monitoring Program performed at the Idaho National Engineering and Environmental Laboratory. This report includes results of sampling performed by the Drinking Water, Effluent, Storm Water, Groundwater Monitoring, and Environmental Surveillance Programs. This report compares the 1998 results to program-specific regulatory guidelines and past data to evaluate trends. The primary purposes of the monitoring and surveillance activities are to evaluate environmental conditions, to provide and interpret data, to verify compliance with applicable regulations or standards, and to ensure protection ofmore » public health and the environment. Surveillance of environmental media did not identify any previously unknown environmental problems or trends, which would indicate a loss of control or unplanned releases from facility operations. The INEEL complied with permits and applicable regulations, with the exception of nitrogen samples in a disposal pond effluent stream and iron and total coliform bacteria in groundwater downgradient from one disposal pond. Data collected by the Environmental Monitoring Program demonstrate that the public health and environment were protected.« less

Geochemical and microbiological assessment of groundwater status: a case study

NASA Astrophysics Data System (ADS)

Preziosi, E.; Del Bon, A.; Amalfitano, S.; Fazi, S.; Zoppini, A.; Parrone, D.; Ghergo, S.

2012-04-01

The qualitative status of the groundwater resources is drawing increasingly attention in relation to the requirements of the European legislative framework. The monitoring strategies are developed by considering the chemical processes affecting groundwater quality. However, despite the use of biological indicators is a common practice for the qualitative assessment of surface waters, a similar approach is hardly being taken into account by policy makers for ground waters. Aquifers are key environments due to the ecosystem capability to ameliorate water quality, e.g. through the natural biodegradation of chemical contaminants. The objective of this research was to characterize a porous water table aquifer from a geochemical and microbiological point of view, aiming to link the hydrogeochemical properties to distribution patterns of the free-living microbial communities. The broader perspective is to integrate the role of microorganisms in the groundwater evolution processes, with new insights in the knowledge of the different microbial communities inhabiting different aquifer typologies. Moreover, microbiological parameters that could be used as a valuable indicator of groundwater quality are sought. A field-scale analysis was performed along the southern Sabatini Mounts aquifer (Central Italy, 50 sampling sites), in an area of about 340 square km, where Pleistocene volcanic products overlay Pleistocene gravel and silt-clay layers, the latter being much more widespread in the downgradient part of the study area. The selected aquifer is contaminated by natural origin elements such as arsenic and fluoride, as well as by human activities, both diffuse (agriculture) and localized, especially in the downgradient part of the aquifer (e.g. landfills, quarries, oil deposits). The main physicochemical parameters of ground waters were determined in situ (redox status, pH, conductivity, T, DO, alkalinity) and in laboratory by ionic chromatography and mass spectrometry (major and trace elements, including arsenic). Total bacterial abundance and vitality (live/dead cell ratio) was determined by combining Flow Cytometry with a double staining fluorescence assay, while the microbial community composition was analyzed through hybridization techniques (CARD-FISH). The hydrogeochemical characterization defined an arsenic rich, mainly alkaline-earth bicarbonate type, which evolves downgradiently towards a more calcium rich water. The variability of bacterial abundance was nonetheless high and the percentage of dead bacterial cells shows a significant correlation with the arsenic concentration. In addition, differences of the taxa along the flow path were detected with an increasing abundance of Delta-Proteobacteria in the more anoxic sites. Overall, our results highlighted that a multidisciplinary approach, which combines geochemical and microbiological surveys, can describe more appropriately ground water status and the evolution processes in the aquifer.

Comparison of chemical hydrogeology of the carbonate peninsulas of Florida and Yucatan

USGS Publications Warehouse

Back, W.; Hanshaw, B.B.

1970-01-01

Aquifers of the peninsulas of Florida and northern Yucatan are Tertiary marine carbonate formations showing many lithologic and faunal similarities. In addition, the tropical to subtropical climates of the two areas are similar, each having annual rainfall of about 1000 to 1500 mm. Despite similarities in these fundamental controls, contrasts in the hydrologic and geochemical systems are numerous and striking. For example, Florida has many rivers; Yucatan has none. Maximum thickness of fresh ground water in Florida is about 700 meters; in the Yucatan it is less than 70 meters. In Florida the gradient of the potentiometric surface averages about 1 meter per kilometer; in the Yucatan it is exceedingly low, averaging about 0.02 meter per kilometer. In Florida the chemical character of water changes systematically downgradient, owing to solution of minerals of the aquifer and corresponding increases in total dissolved solids, sulfate, calcium, and Mg-Ca ratio; in the Yucatan no downgradient change exists, and dominant processes controlling the chemical character of the water are solution of minerals and simple mixing of the fresh water and the body of salt water that underlies the peninsula at shallow depth. Hydrologic and chemical differences are caused in part by the lower altitude of the Yucatan plain. More important, however, these differences are due to the lack of an upper confining bed in Yucatan that is hydrologically equivalent to the Hawthorn Formation of Florida. The Hawthorn cover prevents recharge and confines the artesian water except where it is punctured by sinkholes, but sands and other unconsolidated sediments fill sinkholes and cavities and impede circulation. In the Yucatan the permeability of the entire section is so enormous that rainfall immediately infiltrates to the water table and then moves laterally to discharge areas along the coasts. ?? 1970.

Crude oil in a shallow sand and gravel aquifer-II. Organic geochemistry

USGS Publications Warehouse

Eganhouse, R.P.; Baedecker, M.J.; Cozzarelli, I.M.; Aiken, G.R.; Thorn, K.A.; Dorsey, T.F.

1993-01-01

Crude oil spilled from a pipeline break in a remote area of north-central Minnesota has contaminated a shallow glacial outwash aquifer. Part of the oil was sprayed over a large area to the west of the pipeline and part of it accumulated in an oil body that floats at the water table to the east of the point of discharge. Total dissolved organic carbon (TDOC) concentrations in shallow groundwater collected in the oil spray area reach 16 mg/l. This is nearly an order of magnitude higher than the TDOC concentrations of native groundwater (???2-3 mg/l). The additional TDOC derives from the partial degradation of petroleum residues deposited at the land surface and transported to the aquifer by vertical recharge. In the vicinity of the oil body, TDOC concentrations in groundwater are 48 mg/l, 58% of the TDOC being composed of non-volatile organic C. The majority of the volatile DOC (63%) is a mixture of low-molecular-weight saturated, aromatic and alicyclic hydrocarbons derived from the oil. Downgradient from the oil body along the direction of groundwater flow, concentrations of all measured constituents of the TDOC pool decrease. Concentrations begin to decline most rapidly, however, in the zone where dissolved O2 concentrations begin to increase, ???50 m downgradient from the leading edge of the oil. Within the anoxic zone near the oil body, removal rates of isometric monoaromatic hydrocarbons vary widely. This indicates that the removal processes are mediated mainly by microbiological activity. Molecular and spectroscopic characterization of the TDOC and its spatial and temporal variation provide evidence of the importance of biogeochemical processes in attenuating petroleum contaminants in this perturbed subsurface environment. ?? 1993.

Geophysical and hydrogeological characterisation of the impacts of on-site wastewater treatment discharge to groundwater in a poorly productive bedrock aquifer.

PubMed

Donohue, Shane; McCarthy, Valerie; Rafferty, Patrick; Orr, Alison; Flynn, Raymond

2015-08-01

Contaminants discharging from on-site wastewater treatment systems (OSWTSs) can impact groundwater quality, threatening human health and surface water ecosystems. Risk of negative impacts becomes elevated in areas of extreme vulnerability with high water tables, where thin unsaturated intervals limit vadose zone attenuation. A combined geophysical/hydrogeological investigation into the effects of an OSWTS, located over a poorly productive aquifer (PPA) with thin subsoil cover, aimed to characterise effluent impacts on groundwater. Groundwater, sampled from piezometers down-gradient of the OSWTS percolation area displayed spatially erratic, yet temporally consistent, contaminant distributions. Electrical resistivity tomography identified an area of gross groundwater contamination close to the percolation area and, when combined with seismic refraction and water quality data, indicated that infiltrating effluent reaching the water table discharged to a deeper more permeable zone of weathered shale resting on more competent bedrock. Subsurface structure, defined by geophysics, indicated that elevated chemical and microbiological contaminant levels encountered in groundwater samples collected from piezometers, down-gradient of sampling points with lower contaminant levels, corresponded to those locations where piezometers were screened close to the weathered shale/competent rock interface; those immediately up-gradient were too shallow to intercept this interval, and thus the more impacted zone of the contaminant plume. Intermittent occurrence of faecal indicator bacteria more than 100m down gradient of the percolation area suggested relatively short travel times. Study findings highlight the utility of geophysics as part of multidisciplinary investigations for OSWTS contaminant plume characterisation, while also demonstrating the capacity of effluent discharging to PPAs to impact groundwater quality at distance. Comparable geophysical responses observed in similar settings across Ireland suggest the phenomena observed in this study are more widespread than previously suspected. Copyright © 2015 Elsevier B.V. All rights reserved.

Long-term performance monitoring for a permeable reactive barrier at the U.S. Coast Guard Support Center, Elizabeth City, North Carolina.

PubMed

Puls, R W; Blowes, D W; Gillham, R W

1999-08-12

A continuous hanging iron wall was installed in June, 1996, at the U. S. Coast Guard (USCG) Support Center near Elizabeth City, NC, United States, to treat overlapping plumes of chromate and chlorinated solvent compounds. The wall was emplaced using a continuous trenching machine whereby native soil and aquifer sediment was removed and the iron simultaneously emplaced in one continuous excavation and fill operation. To date, there have been seven rounds (November 1996, March 1997, June 1997, September 1997, December 1997, March 1998, and June 1998) of performance monitoring of the wall. At this time, this is the only full-scale continuous 'hanging' wall installed as a permeable reactive barrier to remediate both chlorinated solvent compounds and chromate in groundwater. Performance monitoring entails the following: sampling of 10-5 cm PVC compliance wells and 15 multi-level samplers for the following constituents: TCE, cis-dichloroethylene (c-DCE), vinyl chloride, ethane, ethene, acetylene, methane, major anions, metals, Cr(VI), Fe(II), total sulfides, dissolved H(2), Eh, pH, dissolved oxygen, specific conductance, alkalinity, and turbidity. Electrical conductivity profiles have been conducted using a Geoprobe to verify emplacement of the continuous wall as designed and to locate upgradient and downgradient wall interfaces for coring purposes. Coring has been conducted in November, 1996, in June and September, 1997, and March, 1998, to evaluate the rate of corrosion on the iron surfaces, precipitate buildup (particularly at the upgradient interface), and permeability changes due to wall emplacement. In addition to several continuous vertical cores, angled cores through the 0.6-m thick wall have been collected to capture upgradient and downgradient wall interfaces along approximate horizontal flow paths for mineralogic analyses.

Design, installation, and performance of a multi-layered permeable reactive barrier, Los Alamos National Laboratory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaszuba, J. P.; Longmire, P. A.; Strietelmeier, E. A.

2004-01-01

A multi-layered permeable reactive barrier (PRB) has been installed in Mortandad Canyon, on the Pajarito Plateau in the north-central part of LANL, to demonstrate in-situ treatment of a suite of contaminants with dissimilar geochemical properties. The PRB will also mitigate possible vulnerabilities from downgradient contaminant movement within alluvial and deeper perched groundwater. Mortandad Canyon was selected as the location for this demonstration project because the flow of alluvial groundwater is constrained by the geology of the canyon, a large network of monitoring wells already were installed along the canyon reach, and the hydrochemistry and contaminant history of the canyon ismore » well-documented. The PRB uses a funnel-and-gate system with a series of four reactive media cells to immobilize or destroy contaminants present in alluvial groundwater, including strontium-90, plutonium-238,239,240, americium-241, perchlorate, and nitrate. The four cells, ordered by sequence of contact with the groundwater, consist of gravel-sized scoria (for colloid removal); phosphate rock containing apatite (for metals and radionuclides); pecan shells and cotton seed admixed with gravel (bio-barrier, to deplete dissolved oxygen and destroy potential RCRA organic compounds, nitrate and perchlorate); and limestone (pH buffering and anion adsorption). Design elements of the PRB are based on laboratory-scale treatability studies and on a field investigation of hydrologic, geochemical, and geotechnical parameters. The PRB was designed with the following criteria: 1-day residence time within the biobarrier, 10-year lifetime, minimization of surface water infiltration and erosion, optimization of hydraulic capture, and minimization of excavated material requiring disposal. Each layer has been equipped with monitoring wells or ports to allow sampling of groundwater and reactive media, and monitor wells are located immediately adjacent to the up- and down-gradient perimeter of the engineered structure. Groundwater sampling upgradient, within, and downgradient of the PRB took place from May through August 2003. Concentrations of strontium-90 have diminished by 80% and 40% within the central portion of the phosphate rock (apatite) and bio-barrier cells, respectively. Higher concentrations of this radionuclide occur in groundwater near the north and south perimeters of the two cells. The non-uniform distribution of strontium-90 may result from varying residence time and saturated thickness of pore water. Initial concentrations of nitrate (8-12 parts per million or ppm as nitrate) and perchlorate (0.035 ppm) have been reduced in the phosphate rock and bio-barrier cells to concentrations that are less than method detection limits (0.01 and 0.002 ppm, respectively). Initial microbial analyses suggest the presence of both dissimilatory perchlorate- and nitrate-reducing bacterial populations, along with production of acetate and propionate, and decreasing dissolved oxygen and pH. The dominant group of perchlorate reducers consists of members of the previously described Dechloromonas genus, in the beta subclass of the Proteobacteria, which together with the Dechlorosoma genus are considered to be the dominant genera in circum-neutral mesophilic environments. Groundwater flow through the multiple PRB is taking place at a very slow rate based on similar concentrations of nitrate, perchlorate, chlorate, and chlorite in the upgradient well MCO-4B and downgradient well MCO-5. Concentrations of these constituents also increase within the limestone cell. Decreased precipitation due to extreme drought is probably responsible for decreasing saturated thickness within both the alluvium and PRB, resulting in stagnant conditions. Varying distributions of ammonium, nitrate, sulfate, iron, and manganese within the phosphate rock, bio-barrier, and limestone cells also support this hypothesis.« less

Remediating Contaminant Plumes in Groundwater with Shallow Excavations Containing Coarse Reactive Media.

PubMed

Hudak, Paul F

2018-02-01

A groundwater flow and mass transport model tested the capability of shallow excavations filled with coarse, reactive media to remediate a hypothetical unconfined aquifer with a maximum saturated thickness of 5 m. Modeled as contaminant sinks, the rectangular excavations were 10 m downgradient of an initial contaminant plume originating from a source at the top of the aquifer. The initial plume was approximately 259 m long, 23 m wide, and 5 m thick, with a downgradient tip located approximately 100 m upgradient of the site boundary. The smallest trench capable of preventing offsite migration was 11 m long (measured perpendicular to groundwater flow), 4 m wide (measured parallel to groundwater flow), and 3 m deep. Results of this study suggest that shallow trenches filled with coarse filter media that partially penetrate unconfined aquifers may be a viable alternative for remediating contaminated groundwater at some sites.

Enhanced bioremediation of BTEX using immobilized nutrients: Field demonstration and monitoring

DOE Office of Scientific and Technical Information (OSTI.GOV)

Borden, R.C.; Goin, R.T.; Kao, C.M.

1996-12-01

A permeable barrier system was developed for controlling the migration of dissolved contaminant plumes in ground water. The barrier system consisted of a line of closely spaced wells installed perpendicular to the contaminant plume. Each well contained concrete briquets that released oxygen and nitrate at a controlled rate, enhancing the aerobic biodegradation of dissolved hydrocarbons in the downgradient aquifer. A full scale permeable barrier system was constructed at a gasoline-spill site near Leland, NC. Initially, increased dissolved oxygen and decreased benzene, toluene, ethylbenzene, and xylene isomer (BTEX) concentrations in the downgradient aquifer indicated that oxygen released from the remediation wellsmore » was enhancing biodegradation. Field tracer tests and soil analyses performed at the conclusion of the project indicated that the aquifer in the vicinity of the remediation wells was being clogged by precipitation from iron minerals.« less

Numerical simulation of steady state three-dimensional groundwater flow near lakes

USGS Publications Warehouse

Winter, Thomas C.

1978-01-01

Numerical simulation of three-dimensional groundwater flow near lakes shows that the continuity of the boundary encompassing the local groundwater flow system associated with a lake is the key to understanding the interaction of a lake with the groundwater system. The continuity of the boundary can be determined by the presence of a stagnation zone coinciding with the side of the lake nearest the downgradient side of the groundwater system. For most settings modeled in this study the stagnation zone underlies the lakeshore, and it generally follows its curvature. The length of the stagnation zone is controlled by the geometry of the lake's drainage basin divide on the side of the lake nearest the downgradient side of the groundwater system. In the case of lakes that lose water to the groundwater system, three-dimensional modeling also allows for estimating the area of lake bed through which outseepage takes place. Analysis of the effects of size and lateral and vertical distribution of aquifers within the groundwater system on the outseepage from lakes shows that the position of the center point of the aquifer relative to the littoral zone on the side of the lake nearest the downgradient side of the groundwater system is a critical factor. If the center point is downslope from this part of the littoral zone, the local flow system boundary tends to be weak or outseepage occurs. If the center point is upslope from this littoral zone, the stagnation zone tends to be stronger (to have a higher head in relation to lake level), and outseepage is unlikely to occur.

Water chemistry near the closed Norman Landfill, Cleveland County, Oklahoma 1995

USGS Publications Warehouse

Schlottmann, Jamie L.

2001-01-01

The Norman Landfill was selected for study as part of the U.S. Geological Survey Toxic Substances Hydrology Program in 1994. The landfill is located south of the City of Norman on alluvial deposits of the Canadian River. Type of waste deposited in the landfill from 1922 to 1973 was largely unrestricted and may include substances now recognized as hazardous. Dissolved and suspended substances leached from wastes in the closed and capped landfill are now in ground water extending toward the Canadian River as a plume of leachate. Water samples were collected from two stock wells, one domestic well, temporary drive-point wells, the Canadian River, and a small intermittent stream hydraulically downgradient of the capped landfill known as the slough. Most constituent concentrations were greater in ground water downgradient from the capped landfill than in background ground water and were greater in the slough than in the Canadian River. Concentrations of most constituents in the Canadian River, other than sulfate, manganese, and iron, were similar to concentrations in background ground water. Some constituents measured in ground-water for this investigation are potential indicators of leachate contamination. Potential indicators that could be used to differentiate leachate contaminated water from uncontaminated ground water of the alluvial aquifer include specific conductance, chloride, alkalinity, dissolved organic carbon, boron, and dD. Specific conductance and chloride were greater in water from wells downgradient of the landfill than water from background wells. Dissolved organic carbon and boron also were greater in the leachate contaminated ground water than in background ground water.

Hydrologic data for a study of pre-Illinoian glacial till in Linn County, Iowa, water year 1990

USGS Publications Warehouse

Bowman, Phillip R.

1991-01-01

Ten unvented, vibrating-wire, pressure transducers with internal thermistors were buried in two boreholes at upgradient and downgradient locations to record hydraulic pressure arid water temperature at selected depths.

A Metal Stable Isotope Approach to Understanding Uranium Mobility Across Roll Front Redox Boundaries

NASA Astrophysics Data System (ADS)

Brown, S. T.; Basu, A.; Christensen, J. N.; DePaolo, D. J.; Heikoop, J. M.; Reimus, P. W.; Maher, K.; Weaver, K. L.

2015-12-01

Sedimentary roll-front uranium (U) ore deposits are the principal source of U for nuclear fuel in the USA and an important part of the current all-of-the-above energy strategy. Mining of roll-front U ore in the USA is primarily by in situ alkaline oxidative dissolution of U minerals. There are significant environmental benefits to in situ mining including no mine tailings or radioactive dust, however, the long-term immobilization of U in the aquifer after the completion of mining remains uncertain. We have utilized the metal stable isotopes U, Se and Mo in groundwater from roll-front mines in Texas and Wyoming to quantify the aquifer redox conditions and predict the onset of U reduction after post mining aquifer restoration. Supporting information from the geochemistry of groundwater and aquifer sediments are used to understand the transport of U prior to and after in situ mining. Groundwater was collected across 4 mining units at the Rosita mine in the Texas coastal plain and 2 mining units at the Smith Ranch mine in the Powder River Basin, Wyoming. In general, the sampled waters are moderately reducing and ore zone wells contain the highest aqueous U concentrations. The lowest U concentrations occur in monitoring wells downgradient of the ore zone. 238U/235U is lowest in downgradient wells and is correlated with aqueous U concentrations. Rayleigh distillation models of the 238U/235U are consistent with U isotope fractionation factors of 1.0004-1.001, similar to lab-based studies. Based on these results we conclude that redox reactions continue to affect U distribution in the ore zone and downgradient regions. We also measured aqueous selenium isotope (δ82Se) and molybdenum isotope (δ98Mo) compositions in the Rosita groundwater. Se(VI) primarily occurs in the upgradient wells and is absent in most ore zone and downgradient wells. Rayleigh distillation models suggest reduction of Se(VI) along the groundwater flow path and when superimposed on the U isotope data Se reduction is favored over U reduction. The δ98Mo of Rosita groundwater is significantly elevated compared to the U ore and is negatively correlated with the groundwater Eh, which suggests localized strong reducing conditions capable of Mo reduction. Ongoing work will determine the Mo isotope systematics of U ores and groundwater from roll-front deposits.

Simulation of groundwater flow and interaction of groundwater and surface water on the Lac du Flambeau Reservation, Wisconsin

USGS Publications Warehouse

Juckem, Paul F.; Fienen, Michael N.; Hunt, Randall J.

2014-01-01

The Lac du Flambeau Band of Lake Superior Chippewa and Indian Health Service are interested in improving the understanding of groundwater flow and groundwater/surface-water interaction on the Lac du Flambeau Reservation (Reservation) in southwest Vilas County and southeast Iron County, Wisconsin, with particular interest in an understanding of the potential for contamination of groundwater supply wells and the fate of wastewater that is infiltrated from treatment lagoons on the Reservation. This report describes the construction, calibration, and application of a regional groundwater flow model used to simulate the shallow groundwater flow system of the Reservation and water-quality results for groundwater and surface-water samples collected near a system of waste-water-treatment lagoons. Groundwater flows through a permeable glacial aquifer that ranges in thickness from 60 to more than 200 feet (ft). Seepage and drainage lakes are common in the area and influence groundwater flow patterns on the Reservation. A two-dimensional, steady-state analytic element groundwater flow model was constructed using the program GFLOW. The model was calibrated by matching target water levels and stream base flows through the use of the parameter-estimation program, PEST. Simulated results illustrate that groundwater flow within most of the Reservation is toward the Bear River and the chain of lakes that feed the Bear River. Results of analyses of groundwater and surface-water samples collected downgradient from the wastewater infiltration lagoons show elevated levels of ammonia and dissolved phosphorus. In addition, wastewater indicator chemicals detected in three downgradient wells and a small downgradient stream indicate that infiltrated wastewater is moving southwest of the lagoons toward Moss Lake. Potential effects of extended wet and dry periods (within historical ranges) were evaluated by adjusting precipitation and groundwater recharge in the model and comparing the resulting simulated lake stage and water budgets to stages and water budgets from the calibrated model. Simulated lake water budgets and water level changes illustrate the importance of understanding the position of a lake within the hydrologic system (headwater or downstream), the type of lake (surface-water drainage or seepage lake), and the role of groundwater in dampening the effects of large-scale changes in weather patterns on lake levels. Areas contributing recharge to drinking-water supply wells on the Reservation were delineated using forward particle tracking from the water table to the well. Monte Carlo uncertainty analyses were used to produce maps showing the probability of groundwater capture for areas around each well nest. At the Main Pumphouse site near the Village of Lac du Flambeau, most of the area contributing recharge to the wells occurs downgradient from a large wetland between the wells and the wastewater infiltration lagoons. Nonetheless, a small potential for the wells to capture infiltrated wastewater is apparent when considering uncertainty in the model parameter values. At the West Pumphouse wells south of Flambeau Lake, most of the area contributing recharge is between the wells and Tippecanoe Lake. The extent of infiltrated wastewater from two infiltration lagoons was tracked using the groundwater flow model and Monte Carlo uncertainty analyses. Wastewater infiltrated from the lagoons flows predominantly south toward Moss Lake as it integrates with the regional groundwater flow system. The wastewater-plume-extent simulations support the area-contributing-recharge simulations, indicating that there is a possibility, albeit at low probability, that some wastewater could be captured by water-supply wells. Comparison of simulated water-table contours indicate that the lagoons may mound the water table approximately 4 ft, with diminishing levels of mounding outward from the lagoons. Four scenarios, representing potential alternatives for wastewater management, were simulated (at current discharge rates) to evaluate the potential extent of wastewater in the aquifer and discharge to surface-water bodies associated with each management scenario. Wastewater simulated to infiltrate through a hypothetical diffuser below a wetland south of the current lagoons appears to discharge to the overlying wetland and would likely discharge to Moss Lake as overland flow. Wastewater simulated to discharge to a small lake (Mindy Lake) between Moss and Fence Lakes appears to spread radically over a large area between the lakes. Wastewater simulated to discharge to lagoons south and northeast of the current lagoons also appears to spread radially, but the areas of the aquifer with the highest probability of encountering waste-water contamination would likely be between the lagoons and the nearest lake, where the wastewater would eventually discharge. Probability results for the wastewater-plume-extent scenarios are sensitive to the number of mathematical water particles used to represent infiltrating wastewater and the level of detail in the synthetic grid used for the probability analysis. Thus, probability results from wastewater-plume-extent simulations are qualitative only; however, it is expected that illustrations of relatively high or low probability will be useful as a general guide for decision making. Management problems requiring quantitative estimates of probability are best re-cast into problems evaluating the area that contributes recharge to the location of interest, which is not dependent upon the number of simulated particles or the resolution of a synthetic grid.

Addendum to the East Tennessee Technology Park Site-Wide Residual Contamination Remedial Investigation Work Plan Oak Ridge, Tennessee

DOE Office of Scientific and Technical Information (OSTI.GOV)

SAIC

2011-04-01

The East Tennessee Technology Park Site-Wide Residual Contamination Remedial Investigation Work Plan (DOE 2004) describes the planned fieldwork to support the remedial investigation (RI) for residual contamination at the East Tennessee Technology Park (ETTP) not addressed in previous Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA) decisions. This Addendum describes activities that will be conducted to gather additional information in Zone 1 of the ETTP for groundwater, surface water, and sediments. This Addendum has been developed from agreements reached in meetings held on June 23, 2010, August 25, 2010, October 13, 2010, November 13, 2010, December 1, 2010,more » and January 13, 2011, with representatives of the U. S. Department of Energy (DOE), U. S. Environmental Protection Agency (EPA), and Tennessee Department of Environment and Conservation (TDEC). Based on historical to recent groundwater data for ETTP and the previously completed Sitewide Remedial Investigation for the ETTP (DOE 2007a), the following six areas of concern have been identified that exhibit groundwater contamination downgradient of these areas above state of Tennessee and EPA drinking water maximum contaminant levels (MCLs): (1) K-720 Fly Ash Pile, (2) K-770 Scrap Yard, (3) Duct Island, (4) K-1085 Firehouse Burn/J.A. Jones Maintenance Area, (5) Contractor's Spoil Area (CSA), and (6) Former K-1070-A Burial Ground. The paper presents a brief summary of the history of the areas, the general conceptual models for the observed groundwater contamination, and the data gaps identified.« less

317/319 Phytoremediation site monitoring report - 2009 growing season : final report.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Negri, C .N.; Benda, P. L.; Gopalakrishnan, G.

2010-02-10

In 1999, Argonne National Laboratory (Argonne) designed and installed a series of engineered plantings consisting of a vegetative cover system and approximately 800 hybrid poplars and willows rooting at various predetermined depths. The plants were installed using various methods including Applied Natural Science's TreeWell{reg_sign} system. The goal of the installation was to protect downgradient surface and groundwater by intercepting the contaminated groundwater with the tree roots, removing moisture from the upgradient soil area, reducing water infiltration, preventing soil erosion, degrading and/or transpiring the residual volatile organic compounds (VOCs), and removing tritium from the subsoil and groundwater. This report presents themore » results of the monitoring activities conducted by Argonne's Energy Systems (ES) Division in the growing season of 2009. Monitoring of the planted trees began soon after the trees were installed in 1999 and has been conducted every summer since then. As the trees grew and consolidated their growth into the contaminated soil and groundwater, their exposure to the contaminants was progressively shown through tissue sampling. During the 2009 sampling campaign, VOC concentrations found in the French Drain area were in general consistent with or slightly lower than the 2008 results. Additionally, closely repeated, stand wide analyses showed contaminant fluctuations that may indicate short-term contaminant depletion in the area of interest of roots. This data will be useful to determine short-term removal rate by the trees. As in previous years, levels in the Hydraulic Control Area were close to background levels except for a few exceptions.« less

Remediation System Evaluation, Shorco South, Mahwah, New Jersey

EPA Pesticide Factsheets

The Shorco South site is located on the southbound side of Route 17 in the Township of Mahwah, New Jersey. The Shorco South site is downgradient of the Shorco North site, which also has ground water impacted with petroleum constituents.

Study of contaminant transport at an open-tipping waste disposal site.

PubMed

Ashraf, Muhammad Aqeel; Yusoff, Ismail; Yusof, Mohamad; Alias, Yatimah

2013-07-01

Field and laboratory studies were conducted to estimate concentration of potential contaminants from landfill in the underlying groundwater, leachate, and surface water. Samples collected in the vicinity of the landfill were analyzed for physiochemical parameters, organic contaminants, and toxic heavy metals. Water quality results obtained were compared from published data and reports. The results indicate serious groundwater and surface water contamination in and around the waste disposal site. Analysis of the organic samples revealed that the site contains polychlorinated biphenyls and other organo-chlorine chemicals, principally chloro-benzenes. Although the amount of PCB concentration discovered was not extreme, their presence indicates a potentially serious environmental threat. Elevated concentrations of lead, copper, nickel, manganese, cadmium, and cobalt at the downgradient indicate that the contamination plume migrated further from the site, and the distribution of metals and metals containing wastes in the site is nonhomogeneous. These results clearly indicate that materials are poorly contained and are at risk of entering the environment. Therefore, full characterization of the dump contents and the integrity of the site are necessary to evaluate the scope of the problem and to identify suitable remediation options.

Assessing the Use of Dry Wells as a Tool for Stormwater Management and Groundwater Recharge in Urban Areas

NASA Astrophysics Data System (ADS)

Edwards, E.; Harter, T.; Fogg, G. E.; Washburn, B.; Bryson, R.; Meirovitz, C.; Fawcett, J.; Kretsinger Grabert, V. J.; Bowles, C.; Carr, M.; Nelson, C.

2014-12-01

Dry wells are gravity-fed, excavated pits with perforated casings used to facilitate stormwater infiltration and groundwater recharge in areas comprised primarily of impermeable surfaces or low permeability soils. Stormwater runoff that would otherwise be routed to streams or drains in urban areas is used as a source of aquifer recharge. However, the potential for groundwater contamination caused by urban runoff bypassing surface soil filtration has prevented more widespread use of dry wells as a recharge mechanism. We present the results of a literature survey to assess the potential of dry wells for safe stormwater recharge. Dry wells have been inculpated in groundwater contamination events, although accusations were typically not backed by scientific data. In 1989 groundwater in Modesto, CA, was contaminated with tetrachloroethylene from a dry cleaning facility. The city had been using dry wells to manage stormwater for more than 50 years without detrimental impacts before the contamination. A USGS monitoring study proved that the contamination was from sewer system leakage, and did not involve the dry wells. Some areas of the country have used dry wells with positive results. The Underground Injection Control system (UICs) study in Portland, OR, has been active for ten years, and currently operates over 9,000 UICs. Initially, a ten foot separation distance was enforced between the seasonal high water table and the bottom perforation of the UIC; however, due to monitoring and modeling results that indicate the protectiveness of groundwater, this distance has been reduced to zero feet. Future work will include a comparative pilot study involving a residential and an industrial site in Elk Grove, CA. The study will use modeling tools to assess the recharge potential and groundwater protectiveness of dry wells. Both sites are outfitted with four monitoring wells each: an upgradient monitoring well, two downgradient monitoring wells, and a vadose zone monitoring well. The results of water quality sampling will determine the contaminants of interest, and a model of the fate and transport of these contaminants in the vadose zone will be coupled with hydraulic models to estimate the response of the hydrogeologic system to dry well recharge, with the goal of creating a tool that can be used to evaluate future dry well locations.

Effects of highway-deicer application on ground-water quality in a part of the Calumet Aquifer, northwestern Indiana

USGS Publications Warehouse

Watson, Lee R.; Bayless, E. Randall; Buszka, Paul M.; Wilson, John T.

2002-01-01

The effects of highway-deicer application on ground-water quality were studied at a site in northwestern Indiana using a variety of geochemical indicators. Site characteristics such as high snowfall rates; large quantities of applied deicers; presence of a high-traffic highway; a homogeneous, permeable, and unconfined aquifer; a shallow water table; a known ground-water-flow direction; and minimal potential for other sources of chloride and sodium to complicate source interpretation were used to select a study area where ground water was likely to be affected by deicer application. Forty-three monitoring wells were installed in an unconfined sand aquifer (the Calumet aquifer) near Beverly Shores in northwestern Indiana. Wells were installed along two transects that approximately paralleled groundwater flow in the Calumet aquifer and crossed US?12. US?12 is a highway that receives Indiana?s highest level of maintenance to maintain safe driving conditions. Ground-water quality and water-level data were collected from the monitoring wells, and precipitation and salt-application data were compiled from 1994 through 1997. The water-quality data indicated that chloride was the most easily traced indicator of highway deicers in ground water. Concentration ratios of chloride to iodide and chloride to bromide and Stiff diagrams of major element concentrations indicated that the principal source of chloride and sodium in ground water from the uppermost one-third to one-half of the Calumet relative electromagnetic conductivity defined a distinct plume of deicer-affected water in the uppermost 8 feet of aquifer at about 9 feet horizontally from the paved roadway edge and a zone of higher conductivity than background in the lower one-third of the aquifer. Chloride and sodium in the deep parts of the aquifer originated from natural sources. Chloride and sodium from highway deicers were present in the aquifer throughout the year. The highest concentrations of chloride and sodium in ground water were determined in samples collected during the spring and summer from wells open to the water table within about 9 feet of the highway. Chloride concentrations in ground water that were attributable to highway deicers also were found in tested wells about 400 feet downgradient from US?12 during the fall and winter and at greater depths than in wells closer to US?12. Chloride concentrations exceeded the U.S. Environmental Protection Agency?s (USEPA) secondary maximum contaminant level of 250 milligrams per liter for drinking water at seven wells downgradient from the highway during late winter, spring, and summer samplings. The chloride standard was exceeded only in water from wells with total depths that are less than about 10 feet below land surface. Sodium concentrations in water periodically exceeded the USEPA drinking-water equivalency level of 20 milligrams per liter in both the uppermost (deicer affected) and lower one-thirds of the aquifer. Sodium concentrations in ground water downgradient from US?12 and in the upper 5 feet of the aquifer also occasionally exceeded drinking-water standards for sodium (160 milligrams per liter) as set by the State of Florida and a standard for taste (200 milligrams per liter) as set by the World Health Organization. Dispersion was identified by analysis of aquifer-test data, isotopic dating of ground water, and water-quality data to be the process most responsible for reducing concentrations of highway deicers in the aquifer. Chemical analyses of the sand composing the aquifer indicated that cation exchange decreased the mass of deicer-related sodium in ground water, although the sand has a limited capacity to sustain the process. Automated daily measurements of specific conductance, correlated to chloride concentrations, indicated that some deicer is retained in the aquifer near the highway throughout the entire year and acts as a continuous chloride source for ground water. Peak concentrations of

Characterization of potential transport pathways and implications for groundwater management near an anticline in the Central Basin area, Los Angeles County, California

USGS Publications Warehouse

Ponti, Daniel J.; Wagner, Brian J.; Land, Michael; Landon, Matthew K.

2014-01-01

The Central Groundwater Basin (Central Basin) of southern Los Angeles County includes ~280 mi2 of the Los Angeles Coastal Plain and serves as the primary source of water for more than two million residents. In the Santa Fe Springs–Whittier–Norwalk area, located in the northeastern part of the basin, several sources of volatile organic compounds have been identified. The volatile organic compunds are thought to have contributed to a large, commingled contaminant plume in groundwater that extends south-southwest downgradient from the Omega Chemical Corporation Superfund Site across folded geologic strata, known as the Santa Fe Springs Anticline. A multifaceted study—that incorporated a three-dimensional sequence-stratigraphic geologic model, two-dimensional groundwater particle-tracking simulations, and new groundwater chemistry data—was conducted to gain insight into the geologic and hydrologic controls on contaminant migration in the study area and to assess the potential for this shallow groundwater contamination to migrate into producing aquifer zones. Conceptual flow models were developed along a flow-parallel cross section based on the modeled stratigraphic architecture, observed geochemistry, and numerical model simulations that generally agree with observed water levels and contaminant distributions. These models predict that contaminants introduced into groundwater at shallow depths near the Omega Chemical Corporation Superfund Site and along the study cross section will likely migrate downgradient to depths intercepted by public supply wells. These conclusions, however, are subject to limitations and simplifications inherent in the modeling approaches used, as well as a significant scarcity of available geologic and hydrogeochemical information at depth and in the downgradient parts of the study area.

Changes in organic matter biodegradatility influencing sulfate reduction in an aquifer contaminated by landfill leachate

USGS Publications Warehouse

Harris, Steve H.; Istok, Jonathan D.; Suflita, Joseph M.

2006-01-01

In situ experiments were conducted to measure sulfate reduction rates and identify rate-limiting factors in a shallow, alluvial aquifer contaminated with municipal landfill leachate. Single-well, push–pull tests conducted in a well adjacent to the landfill with >8 mM dissolved organic carbon (DOC) exhibited a sulfate reduction rate of 3.2 μmol SO4−2 (L sediment)−1 day−1, a value in close agreement with laboratory-derived estimates. Identical tests conducted in wells located 90 m downgradient where DOC levels remained high (>3 mM) showed no detectable sulfate consumption, and laboratory assays confirmed this observation. However, the rates of sulfate reduction in sediment samples obtained from this site were three times larger when they were amended with filter-sterilized groundwater from the upgradient location. The effect of various amendments on sulfate reduction rates was further examined in laboratory incubations using sediment collected from the downgradient site amended with 35S sulfate. Unamended sediments showed only weak conversion of the tracer to 35S sulfide (5 to 7 cpm/cm2), whereas the addition of Desulfovibrio cells increased 35S sulfide production to 44 cpm/cm2. However, the application of heat-killed Desulfovibrio had a similar stimulatory effect, as did a lactate amendment. Collectively, these findings indicate that the lack of measurable sulfate reduction at the downgradient site was not due to the absence of the necessary metabolic potential, the presence of lower sulfate concentration, or the quantity of electron donor, but by its biodegradability. The findings also indicate that field bioaugmentation attempts should be interpreted with caution.

Natural attenuation of trichloroethylene in fractured shale bedrock.

PubMed

Lenczewski, M; Jardine, P; McKay, L; Layton, A

2003-07-01

This paper describes one of the first well-documented field examples of natural attenuation of trichloroethylene (TCE) in groundwater in a fractured shale bedrock. The study was carried out adjacent to a former waste burial site in Waste Area Grouping 5 (WAG5) on the Oak Ridge Reservation, Oak Ridge, TN. A contaminant plume containing TCE and its daughter products were detected downgradient from the buried waste pits, with most of the contamination occurring in the upper 6 m of the bedrock. The monitoring well array consists of a 35-m-long transect of multilevel sampling wells, situated along a line between the waste pits and a seep which discharges into a small stream. Concentrations of volatile organic carbons (VOCs) were highest in the waste trenches and decreased with distance downgradient towards the seep. Sampling wells indicated the presence of overlapping plumes of TCE, cis-dichloroethylene (cDCE), vinyl chloride (VC), ethylene, ethane, and methane, with the daughter products extending further downgradient than the parent (TCE). This type of distribution suggests anaerobic biodegradation. Measurements of redox potential at the site indicated that iron-reduction, sulfate reduction, and potentially methanogensis were occurring and are conducive to dechlorination of TCE. Bacteria enrichment of groundwater samples revealed the presence of methanotrophs, methanogens, iron-reducing bacteria and sulfate-reducing bacteria, all of which have previously been implicated in anaerobic biodegradation of TCE. 16S rDNA sequence from DNA extracted from two wells were similar to sequences of organisms previously implicated in the anaerobic biodegradation of chlorinated solvents. The combined data strongly suggest that anaerobic biodegradation of the highly chlorinated compounds is occurring. Aerobic biodegradation may also be occurring in oxygenated zones, including near a seep where groundwater exits the site, or in the upper bedrock during seasonal fluctuations in water table elevation and oxygen levels.

Screening tool to evaluate the vulnerability of down-gradient receptors to groundwater contaminants from uncapped landfills

USGS Publications Warehouse

Baker, Ronald J.; Reilly, Timothy J.; Lopez, Anthony R.; Romanok, Kristin M.; Wengrowski, Edward W

2015-01-01

A screening tool for quantifying levels of concern for contaminants detected in monitoring wells on or near landfills to down-gradient receptors (streams, wetlands and residential lots) was developed and evaluated. The tool uses Quick Domenico Multi-scenario (QDM), a spreadsheet implementation of Domenico-based solute transport, to estimate concentrations of contaminants reaching receptors under steady-state conditions from a constant-strength source. Unlike most other available Domenico-based model applications, QDM calculates the time for down-gradient contaminant concentrations to approach steady state and appropriate dispersivity values, and allows for up to fifty simulations on a single spreadsheet. Sensitivity of QDM solutions to critical model parameters was quantified. The screening tool uses QDM results to categorize landfills as having high, moderate and low levels of concern, based on contaminant concentrations reaching receptors relative to regulatory concentrations. The application of this tool was demonstrated by assessing levels of concern (as defined by the New Jersey Pinelands Commission) for thirty closed, uncapped landfills in the New Jersey Pinelands National Reserve, using historic water-quality data from monitoring wells on and near landfills and hydraulic parameters from regional flow models. Twelve of these landfills are categorized as having high levels of concern, indicating a need for further assessment. This tool is not a replacement for conventional numerically-based transport model or other available Domenico-based applications, but is suitable for quickly assessing the level of concern posed by a landfill or other contaminant point source before expensive and lengthy monitoring or remediation measures are taken. In addition to quantifying the level of concern using historic groundwater-monitoring data, the tool allows for archiving model scenarios and adding refinements as new data become available.

INFLUENCE OF STRATIGRAPHY ON A DIVING MTBE PLUME AND ITS CHARACTERIZATION: A CASE STUDY

EPA Science Inventory

Conventional conceptual models applied at petroleum release sites are often based on assumptions of vertical contaminant migration through the vadose zone followed by horizontal, downgradient transport at the water table with limited, if any, additional downward migration. Howev...

Potential Aquifer Vulnerability in Regions Down-Gradient from Uranium In Situ Recovery (ISR) Sites

EPA Science Inventory

Sandstone-hosted roll-front uranium ore deposits originate when U(VI) dissolved in groundwater is reduced and precipitated as insoluble U(IV) minerals. Groundwater redox geochemistry, aqueous complexation, and solute migration are instrumental in leaching uranium from source rock...

40 CFR 265.91 - Ground-water monitoring system.

Code of Federal Regulations, 2010 CFR

2010-07-01

... sufficient to yield ground-water samples that are: (i) Representative of background ground-water quality in... not required provided that provisions for sampling upgradient and downgradient water quality will... perforated, and packed with gravel or sand where necessary, to enable sample collection at depths where...

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 ...

40 CFR 257.25 - Assessment monitoring program.

Code of Federal Regulations, 2012 CFR

2012-07-01

...) Minimum distance between upgradient edge of the unit and downgradient monitoring well screen (minimum... that is likely to be without appreciable risk of deleterious effects during a lifetime. For purposes of this subpart, systemic toxicants include toxic chemicals that cause effects other than cancer or...

40 CFR 257.25 - Assessment monitoring program.

Code of Federal Regulations, 2013 CFR

2013-07-01

...) Minimum distance between upgradient edge of the unit and downgradient monitoring well screen (minimum... that is likely to be without appreciable risk of deleterious effects during a lifetime. For purposes of this subpart, systemic toxicants include toxic chemicals that cause effects other than cancer or...

40 CFR 257.25 - Assessment monitoring program.

Code of Federal Regulations, 2011 CFR

2011-07-01

...) Minimum distance between upgradient edge of the unit and downgradient monitoring well screen (minimum... that is likely to be without appreciable risk of deleterious effects during a lifetime. For purposes of this subpart, systemic toxicants include toxic chemicals that cause effects other than cancer or...

The impact of onsite wastewater disposal systems on groundwater in areas inundated by Hurricane Sandy in New York and New Jersey.

PubMed

Fisher, Irene J; Phillips, Patrick J; Colella, Kaitlyn M; Fisher, Shawn C; Tagliaferri, Tristen; Foreman, William T; Furlong, Edward T

2016-06-30

Coastal onsite wastewater disposal systems (OWDS) were inundated by Hurricane Sandy's storm tide. This study compares the shallow groundwater quality (nutrients, pharmaceuticals, and hormones) downgradient of OWDS before and after Hurricane Sandy, where available, and establishes a baseline for wastewater influence on groundwater in coastal communities inundated by Hurricane Sandy. Nutrients and contaminants of emerging concern (CECs) were detected in shallow groundwater downgradient of OWDS in two settings along the New Jersey and New York coastlines: 1) a single, centralized OWDS in a park; and 2) multiple OWDS (cesspools) in low-density residential and mixed-use/medium density residential areas. The most frequently detected pharmaceuticals were lidocaine (40%), carbamazepine (36%), and fexofenadine, bupropion, desvenlafaxine, meprobamate, and tramadol (24-32%). Increases in the number and total concentration of pharmaceuticals after Hurricane Sandy may reflect other factors (seasonality, usage) besides inundation, and demonstrate the importance of analyzing for a wide variety of CECs in regional studies. Published by Elsevier Ltd.

The impact of onsite wastewater disposal systems on groundwater in areas inundated by Hurricane Sandy in New York and New Jersey

USGS Publications Warehouse

Fisher, Irene; Phillips, Patrick J.; Colella, Kaitlyn; Fisher, Shawn C.; Tagliaferri, Tristen N.; Foreman, William T.; Furlong, Edward T.

2016-01-01

Coastal onsite wastewater disposal systems (OWDS) were inundated by Hurricane Sandy's storm tide. This study compares the shallow groundwater quality (nutrients, pharmaceuticals, and hormones) downgradient of OWDS before and after Hurricane Sandy, where available, and establishes a baseline for wastewater influence on groundwater in coastal communities inundated by Hurricane Sandy. Nutrients and contaminants of emerging concern (CECs) were detected in shallow groundwater downgradient of OWDS in two settings along the New Jersey and New York coastlines: 1) a single, centralized OWDS in a park; and 2) multiple OWDS (cesspools) in low-density residential and mixed-use/medium density residential areas. The most frequently detected pharmaceuticals were lidocaine (40%), carbamazepine (36%), and fexofenadine, bupropion, desvenlafaxine, meprobamate, and tramadol (24–32%). Increases in the number and total concentration of pharmaceuticals after Hurricane Sandy may reflect other factors (seasonality, usage) besides inundation, and demonstrate the importance of analyzing for a wide variety of CECs in regional studies.

Ground-water quality in the Davie Landfill, Broward County, Florida

USGS Publications Warehouse

Mattraw, H.C.

1976-01-01

Ground-water adjacent to a disposal pond for septic tank sludge, oil, and grease at the Davie landfill, Broward County, Florida was tested for a variety of ground-water contaminants. Three wells adjacent to the disposal pond yielded water rich in nutrients, organic carbon and many other chemical constituents. Total coliform bacteria ranged from less than 100 to 660 colonies per 100 milliliters in samples collected from the shallowest well (depth 20 feet). At well depths of 35 and 45 feet bacterial counts were less than 20 colonies per 100 milliliters or zero. Concentrations of several constituents in water samples collected from the wells downgradient from the landfill, disposal pond, and an incinerator wash pond were greater than in samples collected from wells immediately upgradient of the landfill. A comparison of sodium-chloride ion ratios indicated that downgradient ground-water contamination was related to the incinerator wash water pond rather than the septic tank sludge pond. (Woodard-USGS)

Flow patterns of lobate debris aprons and lineated valley fill north of Ismeniae Fossae, Mars: Evidence for extensive mid-latitude glaciation in the Late Amazonian

NASA Astrophysics Data System (ADS)

Baker, David M. H.; Head, James W.; Marchant, David R.

2010-05-01

A variety of Late Amazonian landforms on Mars have been attributed to the dynamics of ice-related processes. Evidence for large-scale, mid-latitude glacial episodes existing within the last 100 million to 1 billion years on Mars has been presented from analyses of lobate debris aprons (LDA) and lineated valley fill (LVF) in the northern and southern mid-latitudes. We test the glacial hypothesis for LDA and LVF along the dichotomy boundary in the northern mid-latitudes by examining the morphological characteristics of LDA and LVF surrounding two large plateaus, proximal massifs, and the dichotomy boundary escarpment north of Ismeniae Fossae (centered at 45.3°N and 39.2°E). Lineations and flow directions within LDA and LVF were mapped using images from the Context (CTX) camera, the Thermal Emission Imaging Spectrometer (THEMIS), and the High Resolution Stereo Camera (HRSC). Flow directions were then compared to topographic contours derived from the Mars Orbiter Laser Altimeter (MOLA) to determine the down-gradient components of LDA and LVF flow. Observations indicate that flow patterns emerge from numerous alcoves within the plateau walls, are integrated over distances of up to tens of kilometers, and have down-gradient flow directions. Smaller lobes confined within alcoves and superposed on the main LDA and LVF represent a later, less extensive glacial phase. Crater size-frequency distributions of LDA and LVF suggest a minimum (youngest) age of 100 Ma. The presence of ring-mold crater morphologies is suggestive that LDA and LVF are formed of near-surface ice-rich bodies. From these observations, we interpret LDA and LVF within our study region to result from formerly active debris-covered glacial flow, consistent with similar observations in the northern mid-latitudes of Mars. Glacial flow was likely initiated from the accumulation and compaction of snow and ice on plateaus and in alcoves within the plateau walls as volatiles were mobilized to the mid-latitudes during higher obliquity excursions. Together with similar analyses elsewhere along the dichotomy boundary, these observations suggest that multiple glacial episodes occurred in the Late Amazonian and that LDA and LVF represent significant reservoirs of non-polar ice sequestered below a surface lag for hundreds of millions of years.

Concentrations of hormones, pharmaceuticals and other micropollutants in groundwater affected by septic systems in New England and New York.

PubMed

Phillips, P J; Schubert, C; Argue, D; Fisher, I; Furlong, E T; Foreman, W; Gray, J; Chalmers, A

2015-04-15

Septic-system discharges can be an important source of micropollutants (including pharmaceuticals and endocrine active compounds) to adjacent groundwater and surface water systems. Groundwater samples were collected from well networks tapping glacial till in New England (NE) and sandy surficial aquifer New York (NY) during one sampling round in 2011. The NE network assesses the effect of a single large septic system that receives discharge from an extended health care facility for the elderly. The NY network assesses the effect of many small septic systems used seasonally on a densely populated portion of Fire Island. The data collected from these two networks indicate that hydrogeologic and demographic factors affect micropollutant concentrations in these systems. The highest micropollutant concentrations from the NE network were present in samples collected from below the leach beds and in a well downgradient of the leach beds. Total concentrations for personal care/domestic use compounds, pharmaceutical compounds and plasticizer compounds generally ranged from 1 to over 20 μg/L in the NE network samples. High tris(2-butoxyethyl phosphate) plasticizer concentrations in wells beneath and downgradient of the leach beds (>20 μg/L) may reflect the presence of this compound in cleaning agents at the extended health-care facility. The highest micropollutant concentrations for the NY network were present in the shoreline wells and reflect groundwater that is most affected by septic system discharges. One of the shoreline wells had personal care/domestic use, pharmaceutical, and plasticizer concentrations ranging from 0.4 to 5.7 μg/L. Estradiol equivalency quotient concentrations were also highest in a shoreline well sample (3.1 ng/L). Most micropollutant concentrations increase with increasing specific conductance and total nitrogen concentrations for shoreline well samples. These findings suggest that septic systems serving institutional settings and densely populated areas in coastal settings may be locally important sources of micropollutants to adjacent aquifer and marine systems. Published by Elsevier B.V.

Comparison of tracer methods to quantify hydrodynamic exchange within the hyporheic zone

NASA Astrophysics Data System (ADS)

Engelhardt, I.; Piepenbrink, M.; Trauth, N.; Stadler, S.; Kludt, C.; Schulz, M.; Schüth, C.; Ternes, T. A.

2011-03-01

SummaryHydrodynamic exchange between surface-water and groundwater was studied at a river located within the Rhine Valley in Germany. Piezometric pressure heads and environmental tracers such as temperature, stable isotopes, chloride, X-ray contrast media, and artificial sweetener were investigated within the hyporheic zone and river water plume. Vertical profiles of environmental tracers were collected using multi-level wells within the neutral up-gradient zone, beneath the river bed, and within the horizontal proximal and distal down-gradient zone. Infiltration velocities were calculated from pressure heads, temperature fluctuations and gradients. The amount of river water within groundwater was estimated from vertical profiles of chloride, stable isotopes, and persistent pharmaceuticals. Profiles of stable isotopes and chloride reveal the existence of down-welling within the shallow hyporheic zone that is generated by river bed irregularities. Due to down-welling an above-average migration of river water into the hyporheic zone establishes even under upward hydraulic pressure gradients. The investigated environmental tracers could not distinctively display short-time-infiltration velocities representative for flood waves, while average infiltration velocities calculated over several months are uniform displayed. Based on vertical temperature profiles the down-gradient migration of the river water plume could be observed even after long periods of effluent conditions and over a distance of 200 m from the river bank. X-ray contrast media and artificial sweeteners were observed in high concentrations within the proximal zone, but were not detected at a distance of 200 m from the river bank. Using temperature as environmental tracer within the hyporheic zone may result in overestimating the migration of pollutants within the river water plume as the process of natural attenuation will be neglected. Furthermore, temperature was not able to display the effect of down-welling. Stable isotopes and chloride were found to be suitable environmental tracers to forecast the release and fate of organic contaminants within the hyporheic zone.

Identification of abiotic and biotic reductive dechlorination in a chlorinated ethene plume after thermal source remediation by means of isotopic and molecular biology tools

NASA Astrophysics Data System (ADS)

Badin, Alice; Broholm, Mette M.; Jacobsen, Carsten S.; Palau, Jordi; Dennis, Philip; Hunkeler, Daniel

2016-09-01

Thermal tetrachloroethene (PCE) remediation by steam injection in a sandy aquifer led to the release of dissolved organic carbon (DOC) from aquifer sediments resulting in more reduced redox conditions, accelerated PCE biodegradation, and changes in microbial populations. These changes were documented by comparing data collected prior to the remediation event and eight years later. Based on the premise that dual C-Cl isotope slopes reflect ongoing degradation pathways, the slopes associated with PCE and TCE suggest the predominance of biotic reductive dechlorination near the source area. PCE was the predominant chlorinated ethene near the source area prior to thermal treatment. After thermal treatment, cDCE became predominant. The biotic contribution to these changes was supported by the presence of Dehalococcoides sp. DNA (Dhc) and Dhc targeted rRNA close to the source area. In contrast, dual C-Cl isotope analysis together with the almost absent VC 13C depletion in comparison to cDCE 13C depletion suggested that cDCE was subject to abiotic degradation due to the presence of pyrite, possible surface-bound iron (II) or reduced iron sulphides in the downgradient part of the plume. This interpretation is supported by the relative lack of Dhc in the downgradient part of the plume. The results of this study show that thermal remediation can enhance the biodegradation of chlorinated ethenes, and that this effect can be traced to the mobilisation of DOC due to steam injection. This, in turn, results in more reduced redox conditions which favor active reductive dechlorination and/or may lead to a series of redox reactions which may consecutively trigger biotically induced abiotic degradation. Finally, this study illustrates the valuable complementary application of compound-specific isotopic analysis combined with molecular biology tools to evaluate which biogeochemical processes are taking place in an aquifer contaminated with chlorinated ethenes.

Simulating Bioremediation of Chloroethenes in a Fractured Rock Aquifer.

NASA Astrophysics Data System (ADS)

Curtis, G. P.

2016-12-01

Reactive transport simulations are being conducted to synthesize the results of a field experiment on the enhanced bioremediation of chloroethenes in a heterogeneous fractured-rock aquifer near West Trenton, NJ. The aquifer consists of a sequence of dipping mudstone beds, with water-conducting bedding-plane fractures separated by low-permeability rock where transport is diffusion-limited. The enhanced bioremediation experiment was conducted by injecting emulsified vegetable oil as an electron donor (EOS™) and a microbial consortium (KB1™) that contained dehalococcoides ethenogenes into a fracture zone that had maximum trichloroethene (TCE) concentrations of 84µM. TCE was significantly biodegraded to dichloroethene, chloroethene and ethene or CO2 at the injection well and at a downgradient well. The results also show the concomitant reduction of Fe(III) and S(6) and the production of methane . The results were used to calibrate transport models for quantifying the dominant mass-removal mechanisms. A nonreactive transport model was developed to simulate advection, dispersion and matrix diffusion of bromide and deuterium tracers present in the injection solution. This calibrated model matched tracer concentrations at the injection well and a downgradient observation well and demonstrated that matrix diffusion was a dominant control on tracer transport. A reactive transport model was developed to extend the nonreactive transport model to simulate the microbially mediated sequential dechlorination reactions, reduction of Fe(III) and S(6), and methanogenesis. The reactive transport model was calibrated to concentrations of chloride, chloroethenes, pH, alkalinity, redox-sensitive species and major ions, to estimate key biogeochemical kinetic parameters. The simulation results generally match the diverse set of observations at the injection and observation wells throughout the three year experiment. In addition, the observations and model simulations indicate that a significant pool of TCE that was initially sorbed to either the fracture surfaces or in the matrix was degraded during the field experiment. The calibrated reactive transport model will be used to quantify the extent of chloroethene mass removal from a range of hypothetical aquifers.

Groundwater response to changing water-use practices in sloping aquifers using convolution of transient response functions

USDA-ARS?s Scientific Manuscript database

This study examines the impact of a sloping base on the movement of transients through groundwater systems. Dimensionless variables and regression of model results are employed to develop functions relating the transient change in saturated thickness to the distance upgradient and downgradient from ...

Testing wetland axioms at a watershed scale: Case studies of the aggregate hydrologic effects of non-adjacent wetlands

EPA Science Inventory

Wetlands not adjacent to streams (i.e. “non-adjacent wetlands”) are hypothesized to affect downgradient hydrology in a number of ways. Non-adjacent wetlands may, for example, attenuate peak flows, serve as focal points for groundwater recharge, and decrease streamflow...

A SCREENING MODEL FOR SIMULATING DNAPL FLOW AND TRANSPORT IN POROUS MEDIA: THEORETICAL DEVELOPMENT

EPA Science Inventory

There exists a need for a simple tool that will allow us to analyze a DNAPL contamination scenario from free-product release to transport of soluble constituents to downgradient receptor wells. The objective of this manuscript is to present the conceptual model and formulate the ...

Statistical analysis of lake levels and field study of groundwater and surface-water exchanges in the northeast Twin Cities Metropolitan Area, Minnesota, 2002 through 2015: Chapter A of Water levels and groundwater and surface-water exchanges in lakes of the northeast Twin Cities Metropolitan Area, Minnesota, 2002 through 2015

USGS Publications Warehouse

Jones, Perry M.; Trost, Jared J.; Diekoff, Aliesha L.; Rosenberry, Donald O.; White, Eric A.; Erickson, Melinda L.; Morel, Daniel L.; Heck, Jessica M.

2016-10-19

Water levels declined from 2003 to 2011 in many lakes in Ramsey and Washington Counties in the northeast Twin Cities Metropolitan Area, Minnesota; however, water levels in other northeast Twin Cities Metropolitan Area lakes increased during the same period. Groundwater and surface-water exchanges can be important in determining lake levels where these exchanges are an important component of the water budget of a lake. An understanding of groundwater and surface-water exchanges in the northeast Twin Cities Metropolitan Area has been limited by the lack of hydrologic data. The U.S. Geological Survey, in cooperation with the Metropolitan Council and Minnesota Department of Health, completed a field and statistical study assessing lake-water levels and regional and local groundwater and surface-water exchanges near northeast Twin Cities Metropolitan Area lakes. This report documents the analysis of collected hydrologic, water-quality, and geophysical data; and existing hydrologic and geologic data to (1) assess the effect of physical setting and climate on lake-level fluctuations of selected lakes, (2) estimate potential percentages of surface-water contributions to well water across the northeast Twin Cities Metropolitan Area, (3) estimate general ages for waters extracted from the wells, and (4) assess groundwater inflow to lakes and lake-water outflow to aquifers downgradient from White Bear Lake. Statistical analyses of lake levels during short-term (2002–10) and long-term (1925–2014) periods were completed to help understand lake-level changes across the northeast Twin Cities Metropolitan Area. Comparison of 2002–10 lake levels to several landscape and geologic characteristics explained variability in lake-level changes for 96 northeast Twin Cities Metropolitan Area lakes. Application of several statistical methods determined that (1) closed-basin lakes (without an active outlet) had larger lake-level declines than flow-through lakes with an outlet; (2) closed-basin lake-level changes reflected groundwater-level changes in the Quaternary, Prairie du Chien, and Jordan aquifers; (3) the installation of outlet-control structures, such as culverts and weirs, resulted in smaller multiyear lake-level changes than lakes without outlet-control structures; (4) water levels in lakes primarily overlying Superior Lobe deposits were significantly more variable than lakes primarily overlying Des Moines Lobe deposits; (5) lake-level declines were larger with increasing mean lake-level elevation; and (6) the frequency of some of these characteristics varies by landscape position. Flow-through lakes and lakes with outlet-control structures were more common in watersheds with more than 50 percent urban development compared to watersheds with less than 50 percent urban development. A comparison of two 35-year periods during 1925–2014 revealed that variability of annual mean lake levels in flow-through lakes increased when annual precipitation totals were more variable, whereas variability of annual mean lake levels in closed-basin lakes had the opposite pattern, being more variable when annual precipitation totals were less variable. Oxygen-18/oxygen-16 and hydrogen-2/hydrogen-1 ratios for water samples from 40 wells indicated the well water was a mixture of surface water and groundwater in 31 wells, whereas ratios from water sampled from 9 other wells indicated that water from these wells receive no surface-water contribution. Of the 31 wells with a mixture of surface water and groundwater, 11 were downgradient from White Bear Lake, likely receiving water from deeper parts of the lake. Age dating of water samples from wells indicated that the age of water in the Prairie du Chien and Jordan aquifers can vary widely across the northeast Twin Cities Metropolitan Area. Estimated ages of recharge for 9 of the 40 wells sampled for chlorofluorocarbon concentrations ranged widely from the early 1940s to mid-1970s. The wide range in estimated ages of recharge may have resulted from the wide range in the open-interval lengths and depths for the wells.Results from stable isotope analyses of water samples, lake-sediment coring, continuous seismic-reflection profiling, and water-level and flow monitoring indicated that there is groundwater inflow from nearshore sites and lake-water outflow from deep-water sites in White Bear Lake. Continuous seismic-reflection profiling indicated that deep sections of White Bear, Pleasant, Turtle, and Big Marine Lakes have few trapped gases and little organic material, which indicates where groundwater and lake-water exchanges are more likely. Water-level differences between White Bear Lake and piezometer and seepage measurements in deep waters of the lake indicate that groundwater and lake-water exchange is happening in deep waters, predominantly downgradient from the lake and into the lake sediment. Seepage fluxes measured in the nearshore sites of White Bear Lake generally were higher than seepage fluxes measured in the deep-water sites, which indicates that groundwater-inflow rates at most of the nearshore sites are higher than lake-water outflow from the deep-water sites.

A binomial modeling approach for upscaling colloid transport under unfavorable conditions: Emergent prediction of extended tailing

NASA Astrophysics Data System (ADS)

Hilpert, Markus; Rasmuson, Anna; Johnson, William P.

2017-07-01

Colloid transport in saturated porous media is significantly influenced by colloidal interactions with grain surfaces. Near-surface fluid domain colloids experience relatively low fluid drag and relatively strong colloidal forces that slow their downgradient translation relative to colloids in bulk fluid. Near-surface fluid domain colloids may reenter into the bulk fluid via diffusion (nanoparticles) or expulsion at rear flow stagnation zones, they may immobilize (attach) via primary minimum interactions, or they may move along a grain-to-grain contact to the near-surface fluid domain of an adjacent grain. We introduce a simple model that accounts for all possible permutations of mass transfer within a dual pore and grain network. The primary phenomena thereby represented in the model are mass transfer of colloids between the bulk and near-surface fluid domains and immobilization. Colloid movement is described by a Markov chain, i.e., a sequence of trials in a 1-D network of unit cells, which contain a pore and a grain. Using combinatorial analysis, which utilizes the binomial coefficient, we derive the residence time distribution, i.e., an inventory of the discrete colloid travel times through the network and of their probabilities to occur. To parameterize the network model, we performed mechanistic pore-scale simulations in a single unit cell that determined the likelihoods and timescales associated with the above colloid mass transfer processes. We found that intergrain transport of colloids in the near-surface fluid domain can cause extended tailing, which has traditionally been attributed to hydrodynamic dispersion emanating from flow tortuosity of solute trajectories.

Effects of highway deicing chemicals on shallow unconsolidated aquifers in Ohio, interim report, 1988-93

USGS Publications Warehouse

Jones, A.L.; Sroka, B.N.

1997-01-01

Effects of the application of highway deicing chemicals during winter months on ground- water quality are being studied by the U.S. Geological Survey in cooperation with the Ohio Department of Transportation and the Federal Highway Administration. Eight sites throughout the State were selected along major undivided highways where drainage is by open ditches and ground-water flow is approximately perpendicular to the highway. At these sites, records of deicer application rates are being kept and apparent movement of deicing chemicals through shallow, unconsolidated aquifers is being monitored by means of periodic measurements of specific con ductance and concentrations of dissolved sodium, calcium, and chloride. The counties and corre sponding sections of state routes being monitored are the following: State Route (SR) 3 in Ashland County, SR 84 in Ashtabula County, SR 29 in Champaign County, SR 4 in Clark County, SR 2 in Lucas County, SR 104 in Pickaway County, SR 14 in Portage County, and SR 97 in Richland County. The study began in January 1988 with background data collection, extensive literature review, and site selection. This process, including drilling of wells at the eight selected sites, lasted 3 years. Routine ground-water sampling at 4- to 6-week intervals began in January 1991. A relatively new type of multilevel, passive flow ground-water sampling device was constructed and used. Other conditions monitored on a regular basis included ground-water level (monitored con tinuously), specific conductance, air and soil temperature, precipitation, chloride concentration in soil samples, ground conductivity, and deicing chemical application times and rates. For the interim reporting period, water samples were collected from January 1991 through September 1993. Evidence from water analysis, specific conductance measurements, and surface geophysical measurements indicates that four of the eight sites (Ashtabula County, Lucas County, Portage County, and Richland County sites) are potentially affected by direct application of deic ing chemicals. Climatic data from the period January 1991 through September 1993 show that cold weather, and therefore deicing chemical application rates, varied widely across the State. As a consequence, only minor traces of dissolved chloride above background concentrations (mean, 12-25 mg/L) were determined in ground-water samples from the Pickaway County, Clark County, and Champaign County sites. At the Ashland and Richland County sites, dissolved chlo ride concentrations increased above background concentrations (from the upgradient well, pre sumably unaffected by road salt) only intermittently (mean background concentrations of 3-25 mg/L, rising to a mean of 49-77 mg/L). For the interim reporting period, the mean dissolved chloride concentration for all downgradient wells was about 2 times the background concentra tion (25mg/L) at the Ashland County site (50 mg/L) and 14 times the background concentration (3 mg/L) at the Richland County site (40 mg/L). At the Lucas County, Portage County, and Ash tabula County sites, deicing-chemical application was consistent throughout the winter, and downgradient dissolved chloride concentrations rarely returned to background concentrations (mean 6-32 mg/L) throughout the period. For the interim reporting period, the mean dissolved chloride concentration for all downgradient wells was about 3 times the background concentra tion at the Lucas County site (92 mg/L), 72 times the background concentration at the Portage County site (432 mg/L, 2 downgradient wells), and 21 times the background concentration at the Ashtabula County site (279 mg/L). Other factors that may affect the movement of deicing chemicals through the aquifer were examined, such as precipitation amounts; the types of subsurface materials; ground-water velocity and gradient; hydraulic conductivity; soil type; land use; and ODOT deicing priority. A final report is planned for 2001 afte

Closed-form analytical solutions for assessing the consequences of sea-level rise on unconfined sloping island aquifers

NASA Astrophysics Data System (ADS)

Chesnaux, R.

2016-04-01

Closed-form analytical solutions for assessing the consequences of sea-level rise on fresh groundwater oceanic island lenses are provided for the cases of both strip and circular islands. Solutions are proposed for directly calculating the change in the thickness of the lens, the changes in volume and the changes in travel time of fresh groundwater within island aquifers. The solutions apply for homogenous aquifers recharged by surface infiltration and discharged by a down-gradient, fixed-head boundary. They also take into account the inland shift of the ocean due to land surface inundation, this shift being determined by the coastal slope of inland aquifers. The solutions are given for two simple island geometries: circular islands and strip islands. Base case examples are presented to illustrate, on one hand, the amplitude of the change of the fresh groundwater lens thickness and the volume depletion of the lens in oceanic island with sea-level rise, and on the other hand, the shortening of time required for groundwater to discharge into the ocean. These consequences can now be quantified and may help decision-makers to anticipate the effects of sea-level rise on fresh groundwater availability in oceanic island aquifers.

GeoChip-based analysis of microbial functional gene diversity in a landfill leachate-contaminated aquifer

USGS Publications Warehouse

Lu, Zhenmei; He, Zhili; Parisi, Victoria A.; Kang, Sanghoon; Deng, Ye; Van Nostrand, Joy D.; Masoner, Jason R.; Cozzarelli, Isabelle M.; Suflita, Joseph M.; Zhou, Jizhong

2012-01-01

The functional gene diversity and structure of microbial communities in a shallow landfill leachate-contaminated aquifer were assessed using a comprehensive functional gene array (GeoChip 3.0). Water samples were obtained from eight wells at the same aquifer depth immediately below a municipal landfill or along the predominant downgradient groundwater flowpath. Functional gene richness and diversity immediately below the landfill and the closest well were considerably lower than those in downgradient wells. Mantel tests and canonical correspondence analysis (CCA) suggested that various geochemical parameters had a significant impact on the subsurface microbial community structure. That is, leachate from the unlined landfill impacted the diversity, composition, structure, and functional potential of groundwater microbial communities as a function of groundwater pH, and concentrations of sulfate, ammonia, and dissolved organic carbon (DOC). Historical geochemical records indicate that all sampled wells chronically received leachate, and the increase in microbial diversity as a function of distance from the landfill is consistent with mitigation of the impact of leachate on the groundwater system by natural attenuation mechanisms.

Modeling contamination of shallow unconfined aquifers through infiltration beds

USGS Publications Warehouse

Ostendorf, D.W.

1986-01-01

We model the transport of a simply reactive contaminant through an infiltration bed and underlying shallow, one-dimensional, unconfined aquifer with a plane, steeply sloping bottom in the assumed absence of dispersion and downgradient dilution. The effluent discharge and ambient groundwater flow under the infiltration beds are presumed to form a vertically mixed plume marked by an appreciable radial velocity component in the near field flow region. The near field analysis routes effluent contamination as a single linear reservoir whose output forms a source plane for the one-dimensional, far field flow region downgradient of the facility; the location and width of the source plane reflect the relative strengths of ambient flow and effluent discharge. We model far field contaminant transport, using an existing method of characteristics solution with frame speeds modified by recharge, bottom slope, and linear adsorption, and concentrations reflecting first-order reaction kinetics. The near and far field models simulate transport of synthetic detergents, chloride, total nitrogen, and boron in a contaminant plume at the Otis Air Force Base sewage treatment plant in Barnstable County, Massachusetts, with reasonable accuracy.

Treatment of co-mingled benzene, toluene and TCE in groundwater.

PubMed

Chen, Liang; Liu, Yulong; Liu, Fei; Jin, Song

2014-06-30

This work addressed a hypothetical but practical scenario that includes biological oxidation and reductive dechlorination in treating groundwater containing co-mingled plume of trichloroethene (TCE), benzene and toluene. Groundwater immediately downgradient from the commonly used zero-valent iron (ZVI) has shown alkaline pH (up to 10.7). The elevated pH may influence BTEX compounds (i.e., benzene, toluene, ethyl benzene, and xylenes) biodegradation, which could also be inhibited by elevated concentrations of TCE. Data from this work suggests that the inhibition coefficients (IC) value for 100 μg/L and 500 μg/L of TCE on benzene and toluene degradation are 2.1-2.8 at pH 7.9, and 3.5-6.1 at pH 10.5. For a co-mingled plume, it appears to be more effective to reduce TCE by ZVI before addressing benzene and toluene biodegradation. The ample buffering capacity of most groundwater and the adaptation of benzene and toluene-degrading microbes are likely able to eliminate the adverse influence of pH shifts downgradient from a ZVI-PRB. Copyright © 2014 Elsevier B.V. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

LaFreniere, L. M.; Environmental Science Division

The Commodity Credit Corporation of the U.S. Department of Agriculture (CCC/USDA) formerly operated a grain storage facility at Milford, Nebraska. In May 2008, the CCC/USDA directed the Environmental Science Division of Argonne National Laboratory, as its technical consultant, to develop a work plan for a targeted investigation at the Milford site. The purpose of the targeted investigation is to assess the current extent and configuration of the carbon tetrachloride plume downgradient from the former CCC/USDA facility and proximal to the banks of the Big Blue River, which borders the area of concern to the east, southeast, and northeast. In 1995,more » carbon tetrachloride contamination was detected by the Nebraska Department of Health and Human Services in a private drinking water well and a livestock well 1.25 mi south of Milford (Figure 1.1). The Trojan drinking water well is located directly downgradient (approximately 300 ft east) of the former CCC/USDA facility. Low levels of carbon tetrachloride contamination were also found in the Troyer livestock well, approximately 1,200 ft north of the former CCC/USDA facility.« less

Characterization of surface and ground water δ18O seasonal variation and its use for estimating groundwater residence times

USGS Publications Warehouse

Reddy, Michael M.; Schuster, Paul; Kendall, Carol; Reddy, Micaela B.

2006-01-01

18O is an ideal tracer for characterizing hydrological processes because it can be reliably measured in several watershed hydrological compartments. Here, we present multiyear isotopic data, i.e. 18O variations (δ18O), for precipitation inputs, surface water and groundwater in the Shingobee River Headwaters Area (SRHA), a well-instrumented research catchment in north-central Minnesota. SRHA surface waters exhibit δ18O seasonal variations similar to those of groundwaters, and seasonal δ18O variations plotted versus time fit seasonal sine functions. These seasonal δ18O variations were interpreted to estimate surface water and groundwater mean residence times (MRTs) at sampling locations near topographically closed-basin lakes. MRT variations of about 1 to 16 years have been estimated over an area covering about 9 km2 from the basin boundary to the most downgradient well. Estimated MRT error (±0·3 to ±0·7 years) is small for short MRTs and is much larger (±10 years) for a well with an MRT (16 years) near the limit of the method. Groundwater transit time estimates based on Darcy's law, tritium content, and the seasonal δ18O amplitude approach appear to be consistent within the limits of each method. The results from this study suggest that use of the δ18O seasonal variation method to determine MRTs can help assess groundwater recharge areas in small headwaters catchments.

Characterization of surface and ground water δ18O seasonal variation and its use for estimating groundwater residence times

USGS Publications Warehouse

Reddy, Michael M.; Schuster, Paul F.; Kendall, Carol; Reddy, Micaela B.

2006-01-01

18O is an ideal tracer for characterizing hydrological processes because it can be reliably measured in several watershed hydrological compartments. Here, we present multiyear isotopic data, i.e. 18O variations (δ18O), for precipitation inputs, surface water and groundwater in the Shingobee River Headwaters Area (SRHA), a well-instrumented research catchment in north-central Minnesota. SRHA surface waters exhibit δ18O seasonal variations similar to those of groundwaters, and seasonal δ18O variations plotted versus time fit seasonal sine functions. These seasonal δ18O variations were interpreted to estimate surface water and groundwater mean residence times (MRTs) at sampling locations near topographically closed-basin lakes. MRT variations of about 1 to 16 years have been estimated over an area covering about 9 km2 from the basin boundary to the most downgradient well. Estimated MRT error (±0·3 to ±0·7 years) is small for short MRTs and is much larger (±10 years) for a well with an MRT (16 years) near the limit of the method. Groundwater transit time estimates based on Darcy's law, tritium content, and the seasonal δ18O amplitude approach appear to be consistent within the limits of each method. The results from this study suggest that use of the δ18O seasonal variation method to determine MRTs can help assess groundwater recharge areas in small headwaters catchments.

Bioremediation of a Large Chlorinated Solvent Plume, Dover AFB, DE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bloom, Aleisa C

2015-01-01

Bioremediation of a Large Chlorinated Solvent Plume, Dover AFB, DE Aleisa Bloom, (Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA) Robert Lyon (bob.lyon@aecom.com), Laurie Stenberg, and Holly Brown (AECOM, Germantown, Maryland, USA) ABSTRACT: Past disposal practices at Dover Air Force Base (AFB), Delaware, created a large solvent plume called Area 6 (about 1 mile long, 2,000 feet wide, and 345 acres). The main contaminants are PCE, TCE, and their degradation products. The remedy is in-situ accelerated anaerobic bioremediation (AAB). AAB started in 2006 and is focusing on source areas and downgradient plume cores. Direct-push injections occurred in source areas wheremore » contamination is typically between 5 and 20 feet below ground surface. Lower concentration dissolved-phased contamination is present downgradient at 35 and 50 feet below ground surface. Here, permanent injection/extraction wells installed in transects perpendicular to the flow of groundwater are used to apply AAB. The AAB substrate is a mix of sodium lactate, emulsified vegetable oil, and nutrients. After eight years, dissolved contaminant mass within the main 80-acre treatment area has been reduced by over 98 percent. This successful application of AAB has stopped the flux of contaminants to the more distal portions of the plume. While more time is needed for effects to be seen in the distal plume, AAB injections will soon cease, and the remedy will transition to natural attenuation. INTRODUCTION Oak Ridge National Laboratory Environmental Science Division (ORNL) and AECOM (formerly URS Corporation) have successfully implemented in situ accelerated anaerobic bioremediation (AAB) to remediate chlorinated solvent contamination in a large, multi-sourced groundwater plume at Dover Air Force Base (AFB). AAB has resulted in significant reductions of dissolved phase chlorinated solvent concentrations. This plume, called Area 6, was originally over 1 mile in length and over 2,000 feet wide (Figure 1). It originated from at least four separate source areas that comingled in the subsurface to form the large plume. The major contaminants of concern (COCs) are tetrachloroethene (PCE), trichloroethene (TCE), and 1,1,1-trichloroethane (1,1,1-TCA), which were historically used for degreasing operations in the maintenance of aircraft and support vehicles. Relatively small areas of elevated PCE, TCE, and 1,1,1-TCA were delineated in the shallow portion of the water table aquifer by direct-push groundwater sampling. Focused direct-push AAB treatment occurred in March 2006 at these source areas (Figure 1). Downgradient of the these areas and deeper in the aquifer, AAB treatment was implemented using rows of extraction/injection wells oriented perpendicular to groundwater flow to create multiple reductive zones across the plume cores, defined as areas where more than 1,000 micrograms per liter (ug/L) total solvent concentrations were present. Initial indications of successful degradation were observed within 6 months of starting injections. FIGURE 1. Dover AFB Area 6 plume. This paper describes the AAB implementation and progress of remediation after 8 years of treatment and periodic groundwater monitoring. SITE LITHOLOGY Contamination at the site is limited to the surficial aquifer, which consists of 35 to 50 feet (ft) (11 to 15 meters [m]) of unconsolidated Pleistocene deposits of the Columbia Formation. The Columbia Formation consists of fine to coarse sand with silt and clay lenses and less common gravel lenses. Silts and silty sands are generally encountered to a depth of 10 to 12 ft (3.05 to 3.65 m) below ground surface (bgs) and grade to medium- and coarse-grained sands to a depth of 35 to 50 ft (11 to 15 m) bgs. There is a clay and silt unit (part of the Calvert Formation) below the surficial aquifer that acts as an aquitard to the downward migration of contaminants. The depth to the water table varies across the site but usually ranges from 8 to 15 ft (2.4 to 4.5 m) bgs in the treatment area. REMEDIAL APPROACH AND OPERATIONS Because the Columbia Aquifer is used as a source of potable water off base, the remedial goal is to restore the aquifer to usable condition, i.e., reduce all chemicals of concern to below drinking water maximum contaminant levels (MCLs). To achieve this goal, AAB was selected as the best remedial alternative to reduce the solvent contamination. Source areas with high solvent concentrations were present in the shallow portion of the aquifer. From the source areas, dissolved solvents migrated downgradient and deeper in the aquifer with the flow of groundwater. In the deeper portion of the aquifer, the individual plumes comingle to form the larger Area 6 Plume, which covers approximately 345 acres. Types of Substrate. Previous AAB pilot tests at Dover AFB used either sodium lactate or emulsified vegetable oil (EVO) as substrates to stimulate microbial growth. The best results were obtained with...« less

The thermal impact of subsurface building structures on urban groundwater resources - A paradigmatic example.

PubMed

Epting, Jannis; Scheidler, Stefan; Affolter, Annette; Borer, Paul; Mueller, Matthias H; Egli, Lukas; García-Gil, Alejandro; Huggenberger, Peter

2017-10-15

Shallow subsurface thermal regimes in urban areas are increasingly impacted by anthropogenic activities, which include infrastructure development like underground traffic lines as well as industrial and residential subsurface buildings. In combination with the progressive use of shallow geothermal energy systems, this results in the so-called subsurface urban heat island effect. This article emphasizes the importance of considering the thermal impact of subsurface structures, which commonly is underestimated due to missing information and of reliable subsurface temperature data. Based on synthetic heat-transport models different settings of the urban environment were investigated, including: (1) hydraulic gradients and conductivities, which result in different groundwater flow velocities; (2) aquifer properties like groundwater thickness to aquitard and depth to water table; and (3) constructional features, such as building depths and thermal properties of building structures. Our results demonstrate that with rising groundwater flow velocities, the heat-load from building structures increase, whereas down-gradient groundwater temperatures decrease. Thermal impacts on subsurface resources therefore have to be related to the permeability of aquifers and hydraulic boundary conditions. In regard to the urban settings of Basel, Switzerland, flow velocities of around 1 md -1 delineate a marker where either down-gradient temperature deviations or heat-loads into the subsurface are more relevant. Furthermore, no direct thermal influence on groundwater resources should be expected for aquifers with groundwater thicknesses larger 10m and when the distance of the building structure to the groundwater table is higher than around 10m. We demonstrate that measuring temperature changes down-gradient of subsurface structures is insufficient overall to assess thermal impacts, particularly in urban areas. Moreover, in areas which are densely urbanized, and where groundwater flow velocities are low, appropriate measures for assessing thermal impacts should specifically include a quantification of heat-loads into the subsurface which result in a more diffuse thermal contamination of urban groundwater resources. Copyright © 2017 Elsevier B.V. All rights reserved.

Erkundung und Beweissicherung für eine geothermale Erschließung eines Alpinen Karstaquifers im Tuxertal, Österreich

NASA Astrophysics Data System (ADS)

Sass, Ingo; Heldmann, Claus-Dieter; Schäffer, Rafael

2016-06-01

Karst aquifers may on one hand improve the efficiency of geothermal systems due to increased permeabilities, but on the other hand, high groundwater velocities can reduce the efficiency of the underground heat storage capacity. The marble karst aquifer of the Hochstegen formation was explored and developed for the first time as an intermediate-depth geothermal energy storage system at Finkenberg, Tux valley (Tyrol, Austria). Geological field studies and a spring monitoring program for the project revealed characteristic hydro-chemical signatures related to the catchments in specific tectonic units depending on their lithology. Observations showed that the catchment area of the Hochstegen formation karst aquifer extends up to 2650 m a.s.l. southwest of Finkenberg. In the boreholes, karstification was detected to 400 m below surface (Sass et al., 2016). A monitoring program involving seven springs downgradient of the boreholes has shown that the geothermal project has had no long-term impact on groundwater quality.

Preliminary evaluation of ground-water contamination by coal-tar derivatives, St. Louis Park area, Minnesota

USGS Publications Warehouse

Hult, Marc F.; Schoenberg, Michael E.

1984-01-01

Drift materials on and south of the site have been contaminated by surface spills and by infiltration of contaminated process water. Near the contamination source, a hydrocarbon fluid phase is moving vertically downward relative to movement of the aqueous phase. Fluid pumped from an observation well in this area contained 6,000 milligrams per liter total organic carbon. Dissolved coal-tar constituents in the drift and the uppermost bedrock unit over most of the area, the Platteville aquifer, have moved at least 4,000 feet downgradient to a drift-filled bedrock valley. At the valley, it seems that the Platteville aquifer and the Glenwood confining bed have been removed by erosion and that contaminants with a concentration of approximately 2 milligrams per liter dissolved organic carbon are entering the underlying St. Peter aquifer. Chemical analyses of fluid pumped from observation wells suggest that soluble, low-molecular-weight compounds are moving preferentially through the drift and the Platteville aquifer.

76 FR 20546 - National Oil and Hazardous Substance Pollution Contingency Plan; National Priorities List...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-04-13

... files should avoid the use of special characters, any form of encryption, and be free of any defects or... through the present time. The property is surrounded by woods, open fields, and rural residences. A paint..., chloroethane, 2-hexanone, cadmium, nickel, and lead. The detection of organic constituents in downgradient...

Land management impacts on dairy-derived dissolved organic carbon in ground water

USGS Publications Warehouse

Chomycia, J.C.; Hernes, P.J.; Harter, T.; Bergamaschi, B.A.

2008-01-01

Dairy operations have the potential to elevate dissolved organic carbon (DOC) levels in ground water, where it may interact with organic and inorganic contaminants, fuel denitrification, and may present problems for drinking water treatment. Total and percent bioavailable DOC and total and carbon-specific trihalomethane (THM) formation potential (TTHMFP and STHMFP, respectively) were determined for shallow ground water samples from beneath a dairy farm in the San Joaquin Valley, California. Sixteen wells influenced by specific land management areas were sampled over 3 yr. Measured DOC concentrations were significantly elevated over the background as measured at an upgradient monitoring well, ranging from 13 to 55 mg L-1 in wells downgradient from wastewater ponds, 8 to 30 mg L-1 in corral wells, 5 to 12 mg L-1 in tile drains, and 4 to 15 mg L-1 in wells associated with manured fields. These DOC concentrations were at the upper range or greatly exceeded concentrations in most surface water bodies used as drinking water sources in California. DOC concentrations in individual wells varied by up to a factor of two over the duration of this study, indicating a dynamic system of sources and degradation. DOC bioavailability over 21 d ranged from 3 to 10%, comparable to surface water systems and demonstrating the potential for dairy-derived DOC to influence dissolved oxygen concentrations (nearly all wells were hypoxic to anoxic) and denitrification. TTHMFP measurements across all management units ranged from 141 to 1731 ??g L-1, well in excess of the maximum contaminant level of 80 ??g L-1 established by the Environmental Protection Agency. STHMFP measurements demonstrated over twofold variation (???4 to ???8 mmol total THM/mol DOC) across the management areas, indicating the dependence of reactivity on DOC composition. The results indicate that land management strongly controls the quantity and quality of DOC to reach shallow ground water and hence should be considered when managing ground water resources and in any efforts to mitigate contamination of ground water with carbon-based contaminants, such as pesticides and pharmaceuticals. Copyright ?? 2008 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

Geomorphology and groundwater origin of amphitheater-shaped gullies at Fort Gordon, Georgia, 2010-2012

USGS Publications Warehouse

Landmeyer, James E.; Wellborn, John B.

2013-01-01

Seven amphitheater-shaped gullies at valley heads in the northern part of Fort Gordon, Georgia, were identified by personnel from Fort Gordon and the U.S. Geological Survey during a field investigation of environmental contamination near the cantonment area between 2008 and 2010. Between 2010 and 2012, the amphitheater-shaped gullies were photographed, topographic features were surveyed using a global positioning system device, and the extent of erosion was estimated using Light Detection and Ranging imagery. The seven gullies are distributed across a broad area (and most likely are not the only examples) and have a similar geomorphology that includes (1) an amphitheater (semicircular) shaped escarpment at the upgradient end on a plateau of Upper Eocene sands of no readily discernible elevated catchment area or natural surface-water drainage; (2) a narrow, trench-shaped, flat-bottomed incisement of low-permeability marl at the downgradient end; and (3) steep-sided valley walls, some formed by landslides. Surface-water runoff is an unlikely cause for the amphitheater-shaped gullies, because each valley has a relatively small drainage area of sandy terrain even at those gullies that have recently received discharge from stormwater drains. Also, presumed high rates of runoff and gully formation associated with historic land uses, such as clearcutting, cotton production, and silviculture, would have occurred no later than when the fort was established in the early 1900s. The lack of an elevated catchment area at the headward scarps, the amphitheater shape, and presence of low permeability marl at the base of each feature provides the most convincing lines of evidence for headward erosion by groundwater sapping. The absence of current (2013) seeps and springs at most of the amphitheater-shaped gullies indicates that the gullies may have been formed previously by groundwater sapping under conditions of higher and (or) sustained precipitation amounts, local water-table altitudes, and seepage than current (2013) conditions. One gully characterized by groundwater seepage may support a unique ecological niche that, if assessed to contain endangered species or rare plants, could require protection under State laws.

Natural attenuation of chlorinated volatile organic compounds in ground water at Operable Unit 1, Naval Undersea Warfare Center, Division Keyport, Washington

USGS Publications Warehouse

Dinicola, Richard S.; Cox, S.E.; Landmeyer, J.E.; Bradley, P.M.

2002-01-01

The U.S. Geological Survey (USGS) evaluated the natural attenuation of chlorinated volatile organic compounds (CVOCs) in ground water beneath the former landfill at Operable Unit 1 (OU 1), Naval Undersea Warfare Center, Division Keyport, Washington. The predominant contaminants in ground water are trichloroethene (TCE) and its degradation byproducts cis-1,2-dichloroethene (cisDCE) and vinyl chloride (VC). The Navy planted two hybrid poplar plantations on the landfill in spring of 1999 to remove and control the migration of CVOCs in shallow ground water. Previous studies provided evidence that microbial degradation processes also reduce CVOC concentrations in ground water at OU 1, so monitored natural attenuation is a potential alternative remedy if phytoremediation is ineffective. This report describes the current (2000) understanding of natural attenuation of CVOCs in ground water at OU 1 and the impacts that phytoremediation activities to date have had on attenuation processes. The evaluation is based on ground-water and surface-water chemistry data and hydrogeologic data collected at the site by the USGS and Navy contractors between 1991 and 2000. Previously unpublished data collected by the USGS during 1996-2000 are presented. Natural attenuation of CVOCs in shallow ground water at OU 1 is substantial. For 1999-2000 conditions, approximately 70 percent of the mass of dissolved chlorinated ethenes that was available to migrate from the landfill was completely degraded in shallow ground water before it could migrate to the intermediate aquifer or discharge to surface water. Attenuation of CVOC concentrations appears also to be substantial in the intermediate aquifer, but biodegradation appears to be less significant; those conclusions are less certain because of the paucity of data downgradient of the landfill beneath the tide flats. Attenuation of CVOC concentrations is also substantial in surface water as it flows through the adjacent marsh and out to the tide flats. Attenuation processes other than dilution reduce the CVOC flux in marsh surface water by about 40 percent by the time the water discharges to the tide flats. Despite the importance of natural attenuation processes at reducing both the contaminant concentrations and the contaminant mass at OU 1, natural attenuation alone was not effective enough in the year 2000 to meet current numerical remediation goals for the site. That was in part due to the relatively short distance between the landfill and the adjacent marsh, and in part due to the extremely high CVOC concentrations directly beneath the landfill. Phytoremediation activities had some apparent effect on contaminant concentrations in ground water and surface water, but ground-water redox conditions to date (2000) were not affected by the February 1999 asphalt removal for tree planting. The poplar trees in the phytoremediation plantations were not yet mature in 2000, so the lack of discernible changes to date is understandable. Concentration changes of some redox-sensitive compounds suggest that increased recharge following asphalt removal diluted ambient landfill ground water. CVOC concentrations increased in some downgradient wells in both the northern and southern plantations after asphalt removal, whereas CVOC concentrations decreased in some upgradient wells in the southern plantation. A clear increase in CVOC concentrations in marsh surface water followed asphalt removal, apparently from increased contaminant discharge in ground water beneath the southern plantation. The results of the natural attenuation evaluation suggest than minor modifications to the current sampling plan may be beneficial to understanding the future impacts of phytoremediation and natural attenuation on the fate and distribution of CVOCs at OU 1.

DOE Office of Scientific and Technical Information (OSTI.GOV)

LaFreniere, L. M.; Environmental Science Division

In April 2008, the Commodity Credit Corporation of the U.S. Department of Agriculture (CCC/USDA) conducted groundwater sampling for the analysis of volatile organic compounds (VOCs) in the existing network of monitoring points at Everest, Kansas (Argonne 2008). The objective of the 2008 investigation was to monitor the distribution of carbon tetrachloride contamination in groundwater previously identified in CCC/USDA site characterization and groundwater sampling studies at Everest in 2000-2006 (Argonne 2001, 2003, 2006a,b). The work at Everest is being undertaken on behalf of the CCC/USDA by Argonne National Laboratory, under the oversight of the Kansas Department of Health and Environment (KDHE).more » The findings of the 2008 investigation were as follows: (1) Measurements of groundwater levels obtained manually and through the use of automatic recorders demonstrated a consistent pattern of groundwater flow - and inferred contaminant migration - to the north-northwest from the former CCC/USDA facility toward the Nigh property, and then west-southwest from the Nigh property toward the intermittent creek that lies west of the former CCC/USDA facility and the Nigh property. (2) The range of concentrations and the areal distribution of carbon tetrachloride identified in the groundwater at Everest in April 2008 were generally consistent with previous results. The results of the 2008 sampling (reflecting the period from 2006 to 2008) and the earlier investigations at Everest (representing the period from 2000 to 2006) show that no significant downgradient extension of the carbon tetrachloride plume occurred from 2000 to 2008. (3) The slow contaminant migration indicated by the monitoring data is qualitatively consistent with the low groundwater flow rates in the Everest aquifer unit estimated previously on the basis of site-specific hydraulic testing (Argonne 2006a,b). (4) The April 2008 and earlier sampling results demonstrate that the limits of the plume have been effectively, identified by the existing network of monitoring points and have not changed significantly during the CCC/USDA investigation program. The carbon tetrachloride distribution within the plume has continued to evolve, however, with relatively constant or apparently decreasing contaminant levels at most sampling locations. In response to these findings, the KDHE requested that the CCC/USDA develop a plan for annual monitoring of the groundwater and surface water at Everest, to facilitate continued tracking of the carbon tetrachloride plume at this site (KDHE 2009a). A recommendation for annual sampling (for analyses of VOCs) of 16 existing groundwater monitoring points within and near the identified contaminant migration pathway and surface water sampling at 5 locations along the intermittent creek west (downgradient) of the identified plume was presented by the CCC/USDA (Appendix A) and approved by the KDHE (2009b) for implementation. The monitoring wells will be sampled according to the low-flow procedure, and sample preservation, shipping, and analysis activities will be consistent with previous work at Everest. The annual sampling will continue until identified conditions at the site indicate a technical justification for a change. This report summarizes the results of sampling and monitoring activities conducted at the Everest site since completion of the April 2008 groundwater sampling event (Argonne 2008). The investigations performed during the current review period (May 2008 to October 2009) were as follows: (1) With one exception, the KDHE-approved groundwater and surface water monitoring points were sampled on April 24-27, 2009. In this event, well PT1 was inadvertently sampled instead of the adjacent well MW04. This investigation represents the first groundwater and surface water sampling event performed under the current plan for annual monitoring approved by the KDHE. (2) Ongoing monitoring of the groundwater levels at Everest is performed with KDHE approval. The levels in selected monitoring wells are recorded continuously, by using downhole pressure sensors equipped with automatic data loggers, and periodically are also measured manually. Groundwater level data were recovered during the current review period on September 19, 2008, and on March 25, April 25-27, and October 20, 2009. (3) Argonne experience has demonstrated that the sampling and analysis (for VOCs) of native vegetation, and particularly tree tissues, often provides a sensitive indicator of possible carbon tetrachloride contamination in the surface water or shallow groundwater within the plant rooting zone. With the approval of the CCC/USDA, on August 28, 2009, samples of tree branch tissues were therefore collected for analyses at 18 locations along the intermittent creek west (downgradient) of the former CCC/USDA facility and the Nigh property.« less

Ground-water quality near a sewage-sludge recycling site and a landfill near Denver, Colorado

USGS Publications Warehouse

Robson, Stanley G.

1977-01-01

The Metropolitan Denver Sewage Disposal District and the City and County of Denver operate a sewage-sludge recycling site and a landfill in an area about 15 miles (24 kilometers) east of Denver. The assessment of the effects of these facilities on the ground-water system included determining the direction of ground-water movement in the area, evaluating the impact of the wastedisposal activities on the chemical quality of local ground water, and evaluating the need for continued water-quality monitoring.Surficial geology of the area consists of two principal units: (1) Alluvium with a maximum thickness of about 25 feet (7.6 meters) deposited along stream channels, and (2) bedrock consisting of undifferentiated Denver and Dawson Formations. Ground water in formations less than 350 feet (110 meters) deep moves to the north, as does surface flow, while ground water in formations between 570 and 1,500 feet (170 and 460 meters) deep moves to the west. Estimates of ground-water velocity were made using assumed values for hydraulic conductivity and porosity, and the observed hydraulic gradient from the study area. Lateral velocities are estimated to be 380 feet (120 meters) per year in alluvium and 27 feet (8.2 meters) per year in the upper part of the bedrock formations. Vertical velocity is estimated to be 0.58 foot (0.18 meter) per year in the upper part of the bedrock formations.Potentiometric head decreases with depth in the bedrock formations indicating a potential for downward movement of ground water. However, waterquality analysis and the rate and direction of ground-water movement suggest that ground-water movement in the area is primarily in the lateral rather than the vertical direction. Five wells perforated in alluvium were found to have markedly degraded water quality. One well was located in the landfill and water that was analyzed was obtained from near the base of the buried refuse, two others were located downgradient and near sewage-sludge burial areas, and the remaining two are located near stagnant surface ponds. Concentrations of nitrate in wells downgradient from fields where sludge is plowed into the soil were higher than background concentrations due to the effects of the sludge disposal. No evidence of water-quality degradation was detected in deeper wells perforated in the bedrock formations. Continued water-quality monitoring is needed because of the continuing disposal of wastes. A suggested monitoring program would consist of monitoring wells near the landfill twice a year and monitoring wells near the sludge-disposal areas on an annual basis.

USE OF TRACER INJECTION EXPERIMENTS TO QUANTIFY NITRATE LOSS IN TWO ADJACENT WETLAND STREAMS DRAINING AN AGRICULTURAL FIELD IN THE GEORGIA PIEDMONT

EPA Science Inventory

This study investigated the extent to which nitrate was removed from and/or stored in a small wetland depression downgradient of a 10-ha cattle rotational grazing pasture and a 2.5-ha cropped catchment at the USDA-ARS J. Phil Campbell Sr. Natural Resource Conservation Center in W...

Enhanced Attenuation: Chlorinated Organics

DTIC Science & Technology

2008-04-01

attenuation capacity of the aquifer downgradient from the source (e.g., permeable reactive barriers or phytoremediation ) Selection of EA remedies should be...ranging from very aggressive source destruction and removal methods to less energy-intensive methods, such as phytoremediation . In many cases, it...plumes that include chlorinated organics. The flux of organic-rich leachate to underlying aquifers can create favorable conditions for the natural

Hydrogeology and effects of landfills on ground-water quality, southern Franklin County, Ohio

USGS Publications Warehouse

De Roche, J.T.

1985-01-01

Hydrogeology and water quality were evaluated near five land-fills along a 5-mile segment of the Scioto River valley south of Columbus, Ohio. Heterogenous surficial deposits o sand, gravel, and till up to 160 feet thick are hydraulically connected to the underlying Devonian limestone, the landfills and Scioto River, which has been leveed with 12 to 35 feet of refuse. Ground-water withdrawals caused a maximum 21-foot decline in ground-water levels from 1979 to 1982. The study reach of Scioto River within the influence of ground-water pumping is a losing stream, except for s small segment adjacent to one landfill. Analysis of variance indicated significant difference in ground-water quality between wells upgradient of landfills, down-gradient of landfills, and wells penetrating refuse. Elevated specific conductance and concentrations of total dissolved solids, ammonia, carbon dioxide, and dissolved organic carbon in water from wells downgradient from and penetrating landfills indicate leachate production and migration is occurring. Analysis of bed-material samples from Scioto River and Scioto Big Run revealed concentrations of polynuclear aromatic hydrocarbons ranging from 220 to 9,440 micograms per kilogram of sediment (?g/kg) and concentrations of toxic metals ranging from 1 to 720 ?g/kg. Samples from an upstream control station on Scioto River contained no organic compounds and lower concentrations of metals (ranging from 1 to 260 ?g/kg). Because of multiple land uses within the study area, organic compounds recovered from the streamed sediments cannot be attributed to any single source. The generation of hydrogen sulfide and methane gases, presence of a zone of increased hardness, elevated concentrations of common ionic species, and dominance of ammonia over other nitrogen species indicate that leachate is being produced and its migrating from four landfills and the river levee. Based on hydraulic relationships between ground water and surface water, it is highly probable that ground water contaminated by leachate from the levee and from one of the landfills is discharging to Scioto River. Leachate-enriched groundwater from other landfills also may begin to discharge to the river if water-withdrawal patterns in the study area change.

Hydrogeologic framework, arsenic distribution, and groundwater geochemistry of the glacial-sediment aquifer at the Auburn Road landfill superfund site, Londonderry, New Hampshire

USGS Publications Warehouse

Degnan, James R.; Harte, Philip T.

2013-01-01

Leachate continues to be generated from landfills at the Auburn Road Landfill Superfund Site in Londonderry, New Hampshire. Impermeable caps on the three landfills at the site inhibit direct infiltration of precipitation; however, high water-table conditions allow groundwater to interact with landfill materials from below, creating leachate and ultimately reducing conditions in downgradient groundwater. Reducing conditions can facilitate arsenic transport by allowing it to stay in solution or by liberating arsenic adsorbed to surfaces and from geologic sources, such as glacial sediments and bedrock. The site occupies a 180-acre parcel of land containing streams, ponds, wetlands, and former gravel pits located in glacial sediment. Four areas, totaling 14 acres, including three landfills and one septage lagoon, were used for waste disposal. The site was closed in 1980 after volatile organic compounds associated with industrial waste dumping were detected. The site was added to the U.S. Environmental Protection Agency National Priority List in 1982, and the landfills were capped in 1996. Although volatile organic compound concentrations in groundwater have declined substantially, some measurable concentrations remain. Temporally variable and persistent elevated arsenic concentrations have been measured in groundwater affected by the landfill leachate. Microbial consumption of carbon found in leachate is a driver of reducing conditions that liberate arsenic at the site. In addition to sources of carbon in landfill leachate, wetland areas throughout the site also could contribute carbon to groundwater, but it is currently unknown if any of the wetland areas have downward or reversing gradients that could allow the infiltration of surface water to groundwater. Red-stained sediments and water indicate iron-rich groundwater discharge to surface water and are also associated with elevated concentrations of arsenic in sediment and groundwater. Ironrich groundwater seeps have been observed in the wetland, streams, and pond downgradient of the landfills. Piezometers were installed in some of these locations to confirm groundwater discharge, measure vertical-flow gradients, and to provide a way to sample the discharging groundwater. Understanding the movement of leachate in groundwater is complicated by the presence of preferential flow paths through aquifer materials with differing hydraulic properties; these preferential flow paths can affect rates of recharge, geochemical conditions, and contaminant fluxes. In areas adjacent to the three capped landfills, infiltration of precipitation containing oxygenated water through permeable deltaic sediments in the former gravel pit area causes increases in dissolved oxygen concentrations and decreases in arsenic concentrations. Layered deltaic sediments produce anisotropic hydraulic characteristics and zones of high hydraulic conductivity. The glacial-sediment aquifer also includes glaciolacustrine sediments that have low permeability and limit infiltration at the surface Discharge of leachate-affected groundwater may be limited in areas of organic muck on the bottom of Whispering Pines Pond because the muck may act as a semiconfining layer. Geophysical survey results were used to identify several areas with continuous beds of muck and an underlying highresistivity layer on top of a layer of low resistivity that may represent leachate-affected groundwater. The high-resistivity layer is likely groundwater associated with oxygenated recharge, which would cause arsenic to adsorb onto aquifer sediments and reduce concentrations of dissolved arsenic in groundwater. Surface and borehole geophysical data collected in 2011 were used to identify potentially high-permeability or contaminated zones in the aquifer (preferential flowpaths) as well as low-permeability zones that may promote contamination through back diffusion. Some groundwater in parts of the glacial-sediment aquifer where the leachate plumes were present had low electrical resistivity, low dissolved oxygen, and high concentrations of arsenic. Low-resistivity zones in the underlying bedrock were associated with fractures that also may contain leachate. Although surveying the fractured bedrock was not a specific objective of this study, the results suggest that such a survey would help to determine if leachate and associated concentrations of arsenic are migrating downward into the fractured-bedrock-aquifer system. An uncalibrated, one-dimensional, reactive-transport model was used to assess several conditions that affect arsenic mobility. The results indicate that reductive dissolution and desorption from glacial sediments control dissolved arsenic concentrations. Parameter sensitivity analysis was used to identify key data that are needed in order to accurately assess the time required for arsenic concentrations to fall to levels below the maximum contaminant level at the site. Quantifying this time will require accurate characterization of carbon, sediment-surface sorption sites, and groundwater fluxes at the site.

Steady-State and Transient Groundwater Flow and Advective Transport, Eastern Snake River Plain Aquifer, Idaho National Laboratory and Vicinity, Idaho

NASA Astrophysics Data System (ADS)

Fisher, J. C.; Ackerman, D. J.; Rousseau, J. P.; Rattray, G. W.

2009-12-01

Three-dimensional steady-state and transient models of groundwater flow and advective transport through the fractured basalts and interbedded sediments of the Eastern Snake River Plain (ESRP) aquifer were developed by the U.S. Geological Survey in cooperation with the U.S. Department of Energy. The model domain covers an area of 1,940 square miles that includes most of the Idaho National Laboratory (INL). A 50-year history of waste disposal at the INL has resulted in measurable concentrations of waste contaminants in the aquifer. Numerical models simulated 1980 steady-state conditions and transient flow for 1980-95. In the transient model, streamflow infiltration was the major stress. The models were calibrated using the parameter-estimation program incorporated in MODFLOW-2000. The steady-state model reasonably simulated the observed water-table altitude and gradients. Simulation of transient conditions reproduced changes in the flow system resulting from episodic infiltration from the Big Lost River. Analysis of simulations shows that flow is (1) dominantly horizontal through interflow zones in basalt, vertical anisotropy resulting from contrasts in hydraulic conductivity of different types of basalt and the interbedded sediments, (2) temporally variable due to streamflow infiltration from the Big Lost River, and (3) moving downward downgradient of the INL. Particle-tracking simulations were used to evaluate how simulated groundwater flow paths and travel times differ between the steady-state and transient flow models, and how well model-derived groundwater flow directions and velocities compare to independently-derived estimates. Particle tracking also was used to simulate the growth of tritium plumes originating at two INL facilities over a 16 year period under steady-state and transient flow conditions (1953-68). The shape, dimensions, and areal extent of these plumes were compared to a map of the plumes for 1968 from tritium releases beginning in 1952. Collectively, the particle-tracking simulations indicate that groundwater flow paths and velocities, based on uncalibrated estimates of porosity, are influenced by the dynamic character of the water table and the large contrasts in the hydraulic properties of the media, primarily hydraulic conductivity. Simulation results also indicate that temporal changes in the local hydraulic gradient can account for some of the observed dispersion of contaminants in the aquifer near the major sources of contamination and perhaps the majority of the observed dispersion several miles downgradient of these facilities. The distance downgradient of the facilities where simulated particle plumes were able to reasonably reproduce the 1968 tritium plume extended only to the boundary separating sediment-rich from sediment-poor aquifer layers about 4 mi downgradient of the contaminant source. Particle plumes simulated beyond this boundary were narrow and long, and did not reasonably reproduce the shape, dimensions, or position of the leading edge of the tritium plume; however, few data were available to characterize its true areal extent and shape.

Identifying and Quantifying Chemical Forms of Sediment-Bound Ferrous Iron.

NASA Astrophysics Data System (ADS)

Kohler, M.; Kent, D. B.; Bekins, B. A.; Cozzarelli, I.; Ng, G. H. C.

2015-12-01

Aqueous Fe(II) produced by dissimilatory iron reduction comprises only a small fraction of total biogenic Fe(II) within an aquifer. Most biogenic Fe(II) is bound to sediments on ion exchange sites; as surface complexes and, possibly, surface precipitates; or incorporated into solid phases (e.g., siderite, magnetite). Different chemical forms of sediment-bound Fe(II) have different reactivities (e.g., with dissolved oxygen) and their formation or destruction by sorption/desorption and precipitation/dissolution is coupled to different solutes (e.g., major cations, H+, carbonate). We are quantifying chemical forms of sediment-bound Fe(II) using previously published extractions, novel extractions, and experimental studies (e.g., Fe isotopic exchange). Sediments are from Bemidji, Minnesota, where biodegradation of hydrocarbons from a burst oil pipeline has driven extensive dissimilatory Fe(III) reduction, and sites potentially impacted by unconventional oil and gas development. Generally, minimal Fe(II) was mobilized from ion exchange sites (batch desorption with MgCl2 and repeated desorption with NH4Cl). A < 2mm sediment fraction from the iron-reducing zone at Bemidji had 1.8umol/g Fe(II) as surface complexes or carbonate phases (sodium acetate at pH 5) of which ca. 13% was present as surface complexes (FerroZine extractions). Total bioavailable Fe(III) and biogenic Fe(II) (HCl extractions) was 40-50 umole/g on both background and iron-reducing zone sediments . Approximately half of the HCl-extractable Fe from Fe-reducing zone sediments was Fe(II) whereas 12 - 15% of Fe extracted from background sediments was present as Fe(II). One-third to one-half of the total biogenic Fe(II) extracted from sediments collected from a Montana prairie pothole located downgradient from a produced-water disposal pit was present as surface-complexed Fe(II).

Stable isotopes and volatile organic compounds along seven ground-water flow paths in divergent and convergent flow systems, southern California, 2000

USGS Publications Warehouse

Milby Dawson, Barbara J.; Belitz, Kenneth; Land, Michael; Danskin, Wesley R.

2003-01-01

Ground water is a major source of drinking water in southern California. In an effort to understand factors influencing the susceptibility of ground water tapped by public supply wells, the U.S. Geological Survey has undertaken studies in cooperation with the California State Water Resources Control Board. The vertical and lateral distribution of stable isotopes (deuterium and oxygen-18) and volatile organic compounds (VOC) were examined along seven ground-water flow paths in three urban ground-water basins in southern California: Central Basin in Los Angeles County, Main Basin in Orange County, and Bunker Hill Basin in San Bernardino County. Forty-seven monitoring wells and 100 public supply wells were sampled. The results of this study suggest that the direction of flow and perhaps the degree of confinement in an aquifer system are important controls on the distribution of VOCs. Ground-water flow in the Central and Main Basins in the southern California coastal plain is characterized as radially divergent, with ground-water flow directions moving outward from focused areas of recharge in the unconfined part of the aquifer system toward dispersed areas of discharge in the more confined part. In these basins, there is a volume of water containing VOCs that extends out into a volume of water containing no VOCs. This pattern suggests that radially divergent flow systems disperse VOCs in distal areas. The overall pattern also suggests that ground water in the pressure area is generally insulated from compounds introduced at land surface. These two factors?dispersion of VOCs due to divergence of flow and insulation from land-surface inputs?suggest that the susceptibility of public supply wells to surface contamination decreases with distance in radially divergent, well confined ground-water flow system. In the inland Bunker Hill Basin, ground-water flow is characterized as radially convergent; ground-water flow directions move inward from dispersed recharge areas in the unconfined part of the aquifer system, toward an area of focused discharge in the more confined part. The number of VOCs increased and the concentrations of individual VOCs increased, or remained the same, with increasing travel distance. Methyl tert-butyl ether was detected only in wells in the confined part of the aquifer system, suggesting that the confining units present in the distal part of the Bunker Hill Basin do not prevent VOCs from reaching ground water. These results suggest that VOCs in the Bunker Hill Basin are collected and concentrated as ground water moves downgradient because of radial convergenence of flow. They also suggest that ground water in the Bunker Hill Basin has an increasing opportunity to pick up VOCs introduced at land surface as it moves along a flow path. Some of the downgradient increase in VOC occurrence and concentration may be due to pumping that selectively removes cleaner ground water, thus leaving ground water containing more VOCs in the aquifer. These two factors?collection of VOCs due to convergence of flow and increasing opportunity to collect surficial contaminants perhaps due to a relative absence of confinement?suggest that the susceptibility of public supply wells to surface contamination increases with distance in radially convergent ground-water flow systems, particularly those that are unconfined.

Shallow ground-water flow, water levels, and quality of water, 1980-84, Cowles Unit, Indiana Dunes National Lakeshore

USGS Publications Warehouse

Cohen, D.A.; Shedlock, R.J.

1986-01-01

Since the settling ponds were sealed, the concentration of boron has decreased while concentrations of cadmium, arsenic, zinc, and molybdenum in shallow ground water downgradient of the ponds show no definite trends in time. Arsenic, boron and molybdenum have remained at concentrations above those of shallow ground water in areas unaffected by settling-pond seepage.

In Situ Bioremediation of MTBE in Groundwater

DTIC Science & Technology

2003-06-01

by-products (carbon dioxide and water ). Groundwater leaving the down-gradient edge of the treatment zone contains MTBE at concentrations less than... groundwater treatment approaches ineffective or impracticable. Currently, conventional pump and treat (P&T) followed by aboveground water treatment and...carbon dioxide and water ). Groundwater leaving the down gradient edge of the treatment zone contains MTBE at concentrations less than or equal to the

Review: A Position Paper on Selenium in Ecotoxicology: A Procedure for Deriving Site-Specific Water Quality Criteria

Treesearch

A. Dennis Lemly

1997-01-01

This paper describes a method for deriving site-specific water quality criteria for selenium using a two-step process: (1) gather information on selenium residues and biological effects at the site and in down-gradient systems and (2) examine criteria based on the degree of bioaccumulation, the relationship between mea-sured residues and threshold concentrations for...

Using chemical and microbiological indicators to track the impacts from the land application of treated municipal wastewater and other sources on groundwater quality in a karstic springs basin

NASA Astrophysics Data System (ADS)

Katz, Brian G.; Griffin, Dale W.

2008-08-01

Multiple chemical constituents (nutrients; N, O, H, C stable isotopes; 64 organic wastewater compounds, 16 pharmaceutical compounds) and microbiological indicators were used to assess the impact on groundwater quality from the land application of approximately 9.5 million liters per day of treated municipal sewage effluent to a sprayfield in the 960-km2 Ichetucknee Springs basin, northern Florida. Enriched stable isotope signatures (δ18O and δ2H) were found in water from the effluent reservoir and a sprayfield monitoring well (MW-7) due to evaporation; however, groundwater samples downgradient from the sprayfield have δ18O and δ2H concentrations that represented recharge of meteoric water. Boron and chloride concentrations also were elevated in water from the sprayfield effluent reservoir and MW-7, but concentrations in groundwater decreased substantially with distance downgradient to background levels in the springs (about 12 km) and indicated at least a tenfold dilution factor. Nitrate-nitrogen isotope (δ15N NO3) values above 10 ‰ in most water samples were indicative of organic nitrogen sources except Blue Hole Spring (δ15N NO3 = 4.6 4.9 ‰), which indicated an inorganic source of nitrogen (fertilizers). The detection of low concentrations the insect repellent N, N-diethyl-metatoluamide (DEET), and other organic compounds associated with domestic wastewater in Devil’s Eye Spring indicated that leakage from a nearby septic tank drainfield likely has occurred. Elevated levels of fecal coliforms and enterococci were found in Blue Hole Spring during higher flow conditions, which likely resulted from hydraulic connections to upgradient sinkholes and are consistent with previoius dye-trace studies. Enteroviruses were not detected in the sprayfield effluent reservoir, but were found in low concentrations in water samples from a downgradient well and Blue Hole Spring during high-flow conditions indicating a human wastewater source. The Upper Floridan aquifer in the Ichetucknee Springs basin is highly vulnerable to contamination from multiple anthropogenic sources throughout the springs basin.

Using chemical and microbiological indicators to track the impacts from the land application of treated municipal wastewater and other sources on groundwater quality in a karstic springs basin

USGS Publications Warehouse

Katz, B.G.; Griffin, Dale W.

2008-01-01

Multiple chemical constituents (nutrients; N, O, H, C stable isotopes; 64 organic wastewater compounds, 16 pharmaceutical compounds) and microbiological indicators were used to assess the impact on groundwater quality from the land application of approximately 9.5 million liters per day of treated municipal sewage effluent to a sprayfield in the 960-km2 Ichetucknee Springs basin, northern Florida. Enriched stable isotope signatures (?? 18O and ??2H) were found in water from the effluent reservoir and a sprayfield monitoring well (MW-7) due to evaporation; however, groundwater samples downgradient from the sprayfield have ??18O and ??2H concentrations that represented recharge of meteoric water. Boron and chloride concentrations also were elevated in water from the sprayfield effluent reservoir and MW-7, but concentrations in groundwater decreased substantially with distance downgradient to background levels in the springs (about 12 km) and indicated at least a tenfold dilution factor. Nitrate-nitrogen isotope (??15N-NO3) values above 10 ??? in most water samples were indicative of organic nitrogen sources except Blue Hole Spring (??15N-NO3 = 4.6-4.9 ???), which indicated an inorganic source of nitrogen (fertilizers). The detection of low concentrations the insect repellent N,N-diethyl-metatoluamide (DEET), and other organic compounds associated with domestic wastewater in Devil's Eye Spring indicated that leakage from a nearby septic tank drainfield likely has occurred. Elevated levels of fecal coliforms and enterococci were found in Blue Hole Spring during higher flow conditions, which likely resulted from hydraulic connections to upgradient sinkholes and are consistent with previoius dye-trace studies. Enteroviruses were not detected in the sprayfield effluent reservoir, but were found in low concentrations in water samples from a downgradient well and Blue Hole Spring during high-flow conditions indicating a human wastewater source. The Upper Floridan aquifer in the Ichetucknee Springs basin is highly vulnerable to contamination from multiple anthropogenic sources throughout the springs basin. ?? 2007 Springer-Verlag.

Simulation of advective flow under steady-state and transient recharge conditions, Camp Edwards, Massachusetts Military Reservation, Cape Cod, Massachusetts

USGS Publications Warehouse

Walter, Donald A.; Masterson, John P.

2003-01-01

The U.S. Geological Survey has developed several ground-water models in support of an investigation of ground-water contamination being conducted by the Army National Guard Bureau at Camp Edwards, Massachusetts Military Reservation on western Cape Cod, Massachusetts. Regional and subregional steady-state models and regional transient models were used to (1) improve understanding of the hydrologic system, (2) simulate advective transport of contaminants, (3) delineate recharge areas to municipal wells, and (4) evaluate how model discretization and time-varying recharge affect simulation results. A water-table mound dominates ground-water-flow patterns. Near the top of the mound, which is within Camp Edwards, hydraulic gradients are nearly vertically downward and horizontal gradients are small. In downgradient areas that are further from the top of the water-table mound, the ratio of horizontal to vertical gradients is larger and horizontal flow predominates. The steady-state regional model adequately simulates advective transport in some areas of the aquifer; however, simulation of ground-water flow in areas with local hydrologic boundaries, such as ponds, requires more finely discretized subregional models. Subregional models also are needed to delineate recharge areas to municipal wells that are inadequately represented in the regional model or are near other pumped wells. Long-term changes in recharge rates affect hydraulic heads in the aquifer and shift the position of the top of the water-table mound. Hydraulic-gradient directions do not change over time in downgradient areas, whereas they do change substantially with temporal changes in recharge near the top of the water-table mound. The assumption of steady-state hydraulic conditions is valid in downgradient area, where advective transport paths change little over time. In areas closer to the top of the water-table mound, advective transport paths change as a function of time, transient and steady-state paths do not coincide, and the assumption of steady-state conditions is not valid. The simulation results indicate that several modeling tools are needed to adequately simulate ground-water flow at the site and that the utility of a model varies according to hydrologic conditions in the specific areas of interest.

Hydrology and chemistry of selected prairie wetlands in the Cottonwood Lake area, Stutsman County, North Dakota, 1979-82

USGS Publications Warehouse

LaBaugh, J.W.; Winter, T.C.; Adomaitis, V.A.; Swanson, G.A.

1987-01-01

The relation of hydrologic setting and temporal variability in hydrology to nutrient content and geochemical characteristics of a group of prairie wetlands and adjacent ground water was studied during the period 1979-82. Although data were collected from many wetlands and wells at the study site, emphasis in this report primarily is on four wetlands two seasonal and two semipermanent and four wells contiguous to them along a hydrologic section. The seasonal wetlands, T8 and T3, contained water only for a few weeks to months after filling in spring and early summer; both were completely dry by August. The semipermanent wetlands, PI and P8, contained water throughout each year and were ice covered in winter. One wetland, T8, recharges ground water. Wetlands PI and P8 are in areas of ground-water discharge. None of the wetlands received water by channelized surface-water inlets. Only wetland P8 had a channelized surface-water outlet. Ground-water-level data showed that high points of the water table did not always occur beneath land-surface highs. Reversals of ground-water flow occurred occasionally between two of the wetlands, T3 and PI.Significant differences existed in the chemical composition of the wetlands based on their hydrologic setting. In general, the dominant cation and anion in the wetlands were potassium and bicarbonate in wetland T8, calcium and sulfate in wetland T3, magnesium and sulfate in wetland PI, and magnesium and bicarbonate in wetland P8. Significant seasonal differences existed in the water chemistry of the wetlands in ground-water discharge areas. Water in three of the wetlands, T3, Pi, and P8, was most dilute while they filled in spring after icemelt. Concentration increased during the open-water period, and two of the wetlands, PI and P8, became most concentrated under ice cover. Concentrations of total phosphorus and total nitrogen were greatest in wetlands in areas of ground-water recharge and least in wetlands in areas of ground-water discharge. Differences in the chemistry of water from wells in the adjacent ground water resulted primarily from the positions of the wells in the ground-water flow system. The chemical type of water from well 12, which was located in a ground-water recharge area, was calcium sodium bicarbonate. Water from well 4, located downgradient from wetland T8, and from well 16, located downgradient from wetland PI, typically was a calcium sulfate type. Water from well 13, located between wetlands T3 and PI in an area of changing ground-water flow directions, was a magnesium sulfate type. Data from this study show that an understanding of hydrologic conditions is important in the interpretation of the water chemistry of wetlands in the study area.

Laboratory column experiments and transport modeling to evaluate retardation of uranium in an aquifer downgradient of a uranium in-situ recovery site

DOE PAGES

Dangelmayr, Martin A.; Reimus, Paul W.; Wasserman, Naomi L.; ...

2017-05-01

The purpose of this study was to determine the attenuation potential and retardation of uranium in sediments taken from boreholes at the Smith-Ranch Highland in-situ recovery (ISR) site. Five column experiments with four different sediments were conducted to study the effects of variable mineralogy and alkalinity on uranium breakthrough. Uranium transport was modeled with PHREEQC using a generalized composite surface complexation model (GC SCM) with one, two, and, three generic surfaces, respectively. Reactive surface areas were approximated with PEST using BET derived surface areas to constrain fitting parameters. Uranium breakthrough was delayed by a factor of 1.68, 1.69 and 1.47more » relative to the non-reactive tracer for three of the 5 experiments at an alkalinity of 540 mg/l. A sediment containing smectite and kaolinite retained uranium by a factor of 2.80 despite a lower measured BET surface area. Decreasing alkalinity to 360 mg/l from 540 mg/l increased retardation by a factor of 4.26. Model fits correlated well to overall BET surface area in the three columns where clay content was less than 1%. For the sediment with clay, models consistently understated uranium retardation when reactive surface sites were restricted by BET results. Calcite saturation was shown to be a controlling factor for uranium desorption as the pH of the system changes. A pH of 6 during a secondary background water flush remobilized previously sorbed uranium resulting in a secondary uranium peak at twice the influent concentrations. Furthermore, this study demonstrates the potential of GC SCM models to predict uranium transport in sediments with homogenous mineral composition, but highlights the need for further research to understand the role of sediment clay composition and calcite saturation in uranium transport.« less

Laboratory column experiments and transport modeling to evaluate retardation of uranium in an aquifer downgradient of a uranium in-situ recovery site

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dangelmayr, Martin A.; Reimus, Paul W.; Wasserman, Naomi L.

The purpose of this study was to determine the attenuation potential and retardation of uranium in sediments taken from boreholes at the Smith-Ranch Highland in-situ recovery (ISR) site. Five column experiments with four different sediments were conducted to study the effects of variable mineralogy and alkalinity on uranium breakthrough. Uranium transport was modeled with PHREEQC using a generalized composite surface complexation model (GC SCM) with one, two, and, three generic surfaces, respectively. Reactive surface areas were approximated with PEST using BET derived surface areas to constrain fitting parameters. Uranium breakthrough was delayed by a factor of 1.68, 1.69 and 1.47more » relative to the non-reactive tracer for three of the 5 experiments at an alkalinity of 540 mg/l. A sediment containing smectite and kaolinite retained uranium by a factor of 2.80 despite a lower measured BET surface area. Decreasing alkalinity to 360 mg/l from 540 mg/l increased retardation by a factor of 4.26. Model fits correlated well to overall BET surface area in the three columns where clay content was less than 1%. For the sediment with clay, models consistently understated uranium retardation when reactive surface sites were restricted by BET results. Calcite saturation was shown to be a controlling factor for uranium desorption as the pH of the system changes. A pH of 6 during a secondary background water flush remobilized previously sorbed uranium resulting in a secondary uranium peak at twice the influent concentrations. Furthermore, this study demonstrates the potential of GC SCM models to predict uranium transport in sediments with homogenous mineral composition, but highlights the need for further research to understand the role of sediment clay composition and calcite saturation in uranium transport.« less

Water quality of the Apalachicola-Chattahoochee-Flint and Ocmulgee river basins related to flooding from Tropical Storm Alberto; pesticides in urban and agricultural watersheds, and nitrate and pesticides in ground water, Georgia, Alabama, and Florida

USGS Publications Warehouse

Hippe, D.J.; Wangsness, D.J.; Frick, E.A.; Garrett, J.W.

1994-01-01

This report presents preliminary water-quality information from three studies that are part of the National Water-Quality Assessment (NAWQA) Program in the Apalachicola-Chattahoochee-Flint (ACF) River basin and the adjacent Ocmulgee River basin. During the period July 3-7, 1994, heavy rainfall from tropical storm Alberto caused record flooding on the Ocmulgee and Flint Rivers and several of their tributaries. Much of the nitrogen load transported during the flooding was as organic nitrogen generally derived from organic detritus, rather than nitrate derived from other sources, such as fertilizer. More than half the mean annual loads of total phosphorus and organic nitrogen were trans- ported in the Flint and Ocmulgee Rivers during the flood. Fourteen herbicides, five insecticides, and one fungicide were detected in floodwaters of the Ocmulgee, Flint, and Apalachicola Rivers. In a second study, water samples were collected at nearly weekly intervals from March 1993 through April 1994 from one urban and two agricultural watersheds in the ACF River basin, and analyzed for 84 commonly used pesticides. More pesticides were detected and at generally higher concentrations in water from the urban watershed than the agricultural water- sheds, and a greater number of pesticides were persistent throughout much of the year in the urban watershed. Simazine exceeded U.S. Environmental Protection Agency (EPA) drinking-water standards in one of 57 samples from the urban watershed. In a third study, 38 wells were installed in surficial aquifers adjacent to and downgradient of farm fields within agricultural areas in the southern ACF River basin. Even though regional aquifers are generally used for irrigation and domestic- and public-water supplies, degradation of water quality in the surficial aquifers serves as an early warning of potential contamination of regional aquifers. Nitrate concentrations were less than 3 mg/L as N (indicating minimal effect of human activities) in water from about two-thirds of the wells. Water from the remaining wells had elevated nitrate con- centrations, probably the result of human activity. Nitrate concentrations in two of these wells exceeded EPA drinking-water standards. Water samples from eight wells had pesticide concentrations above method detection limits. With the exception of two samples for shallow ground-water wells and one surface-water sample from the urban watershed, concentrations of nitrate nitrogen and detected pesticides were below EPA standards and guidelines for drinking water. However, concentrations of the insecticides chlorpyrifos, carbaryl, and diazinon in the surface-water samples approached or exceeded guidelines for protection of aquatic life.

Corrective action plan for corrective action Unit 342: Area 23 Mercury Fire Training Pit, Nevada Test Site, Nevada

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nacht, S.

1999-08-01

The Mercury Fire Training Pit is a former fire training area located in Area 23 of the Nevada Test Site (NTS). The Mercury Fire Training Pit was used from approximately 1965 to the early 1990s to train fire-fighting personnel at the NTS, and encompasses an area approximately 107 meters (m) (350 feet [ft]) by 137 m (450 ft). The Mercury Fire Training Pit formerly included a bermed burn pit with four small burn tanks, four large above ground storage tanks an overturned bus, a telephone pole storage area, and areas for burning sheds, pallets, and cables. Closure activities will includemore » excavation of the impacted soil in the aboveground storage tank and burn pit areas to a depth of 1.5 m (5 ft), and excavation of the impacted surface soil downgradient of the former ASTs and burnpit areas to a depth of 0.3 m (1 ft). Excavated soil will be disposed in the Area 6 Hydrocarbon Landfill at the NTS.« less

Denitrification in a sand and gravel aquifer

USGS Publications Warehouse

Smith, R.L.; Duff, J.H.

1988-01-01

Denitrification was assayed by the acetylene blockage technique in slurried core material obtained from a freshwater sand and gravel aquifer. The aquifer, which has been contaminated with treated sewage for more than 50 years, had a contaminant plume greater than 3.5-km long. Near the contaminant source, groundwater nitrate concentrations were greater than 1 mM, whereas 0.25 km downgradient the central portion of the contaminant plume was anoxic and contained no detectable nitrate. Samples were obtained along the longitudinal axis of the plume (0 to 0.25 km) at several depths from four sites. Denitrification was evident at in situ nitrate concentrations at all sites tested; rates ranged from 2.3 to 260 pmol of N20 produced (g of wet sediment)-' h-'. Rates were highest nearest the contaminant source and decreased with increasing distance downgradient. Denitrification was the predominant nitrate-reducing activity; no evidence was found for nitrate reduction to ammonium at any site. Denitrifying activity was carbon limited and not nitrate limited, except when the ambient nitrate level was less than the detection limit, in which case, even when amended with high concentrations of glucose and nitrate, the capacity to denitrify on a short-term basis was lacking. These results demonstrate that denitrification can occur in groundwater systems and, thereby, serve as a mechanism for nitrate remoyal from groundwater.

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

USGS Publications Warehouse

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

2011-01-01

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

Surface-Water and Ground-Water Interactions in the Central Everglades, Florida

USGS Publications Warehouse

Harvey, Judson W.; Newlin, Jessica T.; Krest, James M.; Choi, Jungyill; Nemeth, Eric A.; Krupa, Steven L.

2004-01-01

Recharge and discharge are hydrological processes that cause Everglades surface water to be exchanged for subsurface water in the peat soil and the underlying sand and limestone aquifer. These interactions are thought to be important to water budgets, water quality, and ecology in the Everglades. Nonetheless, relatively few studies of surface water and ground water interactions have been conducted in the Everglades, especially in its vast interior areas. This report is a product of a cooperative investigation conducted by the USGS and the South Florida Water Management District (SFWMD) aimed at developing and testing techniques that would provide reliable estimates of recharge and discharge in interior areas of WCA-2A (Water Conservation Area 2A) and several other sites in the central Everglades. The new techniques quantified flow from surface water to the subsurface (recharge) and the opposite (discharge) using (1) Darcy-flux calculations based on measured vertical gradients in hydraulic head and hydraulic conductivity of peat; (2) modeling transport through peat and decay of the naturally occurring isotopes 224Ra and 223Ra (with half-lives of 4 and 11 days, respectively); and (3) modeling transport and decay of naturally occurring and 'bomb-pulse' tritium (half-life of 12.4 years) in ground water. Advantages and disadvantages of each method for quantifying recharge and discharge were compared. In addition, spatial and temporal variability of recharge and discharge were evaluated and controlling factors identified. A final goal was to develop appropriately simplified (that is, time averaged) expressions of the results that will be useful in addressing a broad range of hydrological and ecological problems in the Everglades. Results were compared with existing information about water budgets from the South Florida Water Management Model (SFWMM), a principal tool used by the South Florida Water Management District to plan many of the hydrological aspects of the Everglades restoration. A century of water management for flood control and water storage in the Everglades resulted in the creation of the Water Conservation Areas (WCAs). Construction of the major canals began in the 1910s and the systems of levees that enclose the basins and structures that move water between basins were largely completed by the 1950s. The abandoned wetlands that remained outside of the Water Conservation areas tended to dry out and subside by 10 feet or more, which created abrupt transitions in land-surface elevations and water levels across the levees. The increases in topographic and hydraulic gradients near the margins of the WCAs, along with rapid pumping of water between basins to achieve management objectives, have together altered the patterns of recharge and discharge in the Everglades. The most evident change is the increase in the magnitude of recharge (on the upgradient side) and discharge (on the downgradient side) of levees separating WCA-2A from other basins or areas outside. Recharge and discharge in the vast interior of WCA-2A also likely have increased, but fluxes in the interior wetlands are more subtle and more difficult to quantify compared with areas close to the levees. Surface-water and ground-water interactions differ in fundamental ways between wetlands near WCA-2A's boundaries and wetlands in the basin's interior. The levees that form the WCA's boundaries have introduced step functions in the topographic and hydraulic gradients that are important as a force to drive water flow across the wetland ground surface. The resulting recharge and discharge fluxes tend to be unidirectional (connecting points of recharge on the upgradient side of the levee with points of discharge on the downgradient side), and fluxes are also relatively steady in magnitude compared with fluxes in the interior. Recharge flow paths are also relatively deep in their extent near levees, with fluxes passing entirely through the 1-m peat layer and inte

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

NASA Astrophysics Data System (ADS)

Christensen, T. H.

2001-05-01

The contamination by leachate of the upper aquifer at the Grindsted Landfill (Denmark) stretches about 300 m downgradient from the landfill. The plume has been described with respect to water chemistry, sediment chemistry, pollutant distribution, microbial counts, PLFA and redox rates determined by unamended bioassays. This presentation summaries the findings and discusses unanswered questions. The landfill was active from 1930 to the mid 1970 and has no engineered leachate collection system. Leachate from municipal as well as from industrial waste has entered the aquifer for more than thirty years. The redox conditions change from strongly anaerobic (methanogenic, sulfate reducing, iron reducing) close to the landfill over manganese reduction and denitrification to aerobic conditions in the outskirts of the plume The redox conditions were determined from groundwater sample composition, hydrogen concentrations and sediment chemistry. The plume showed strong attenuation of aromatic compounds within the first 100 m downgradient of the landfill. Degradation experiments (batch, in-situ testers, long term field injection experiments) could not fully document degradation of all the compounds. MPN-measurements of methanogens, sulfate-reducers, iron-reducers, manganese-reducers and denitrifiers showed abundance of all groups with a slight trend with the redox conditions. PLFA measurements did not provide much insight into the microbial populations of the plume, but confirmed some previous observations. Bioassays gave estimates of the rates of the various redox processes, but showed for some samples more simultaneous redox processes. More than 25 years of work has been put into the Grindsted Landfill leachate plume. References Bjerg, P.L., Rugge, K., Cortsen, J., Nielsen, P.H. & Christensen, T.H. (1999): Degradation of aromatic and chlorinated aliphatic hydrocarbons in the anaerobic part of the Grindsted Landfill leachate plume: In situ microcosm and laboratory batch experiments. Ground Water, 37, 113-121. Bjerg, P.L., Rugge, K., Pedersen, J.K. & Christensen, T.H. (1995): Distribution of redox sensitive groundwater quality parameters downgradient of a landfill (Grindsted, Denmark). Environmental Science and Technology, 29, 1387-1394. Heron, G., Bjerg, P.L., Gravesen, P., Ludvigsen, L. & Christensen, T.H. (1998): Geology and sediment geochemistry of a landfill leachate contaminated aquifer (Grindsted, Denmark). Journal of Contaminant Hydrology, 29, 301-317. Jakobsen, R., Albrechtsen, H.-J., Rasmussen, M., Bay, H., Bjerg, P.L. & Christensen, T.H. (1998): H2 concentrations in a landfill leachate plume (Grindsted, Denmark): In situ energetics of terminal electron acceptor processes. Environmental Science and Technology, 32, 2142-2148. Ludvigsen, L., Albrechtsen, H.-J., Heron, G., Bjerg, P.L. & Christensen, T.H. (1998): Anaerobic microbial redox processes in a landfill leachate contaminated aquifer (Grindsted, Denmark). Journal of Contaminant Hydrology, 33, 273-291. Ludvigsen, L., Albrechtsen, H.-J., Ringelberg, D., Ekelund, F. & Christensen, T.H. (1999): Distribution and composition of microbial populations in a landfill leachate contaminated aquifer (Grindsted, Denmark). Microbial Ecology, 37, (3), 197-207. Rugge, K., Bjerg, P.L. & Christensen, T.H. (1995): Distribution of organic compounds from municipal solid waste in the groundwater downgradient of a landfill (Grindsted, Denmark). Environmental Science and Technology, 29, 1395-1400.

Arsenic Movement From Sediment to Water: Microbes and Mobilization in a Contaminated Lake

NASA Astrophysics Data System (ADS)

Keimowitz, A. R.; Mailloux, B. J.; Chillrud, S. N.; Ross, J.; Wovkulich, K.; McNamara, P.; Alexandrova, E.; Thompson, L.

2008-12-01

Union Lake (Millville, NJ), a reservoir downstream from the Vineland Chemical Company Superfund site, has bottom sediments that are highly contaminated with arsenic (>1 g/kg). Offsite As transport was investigated. Because the lake is a result of damming, it is perched above the water table and therefore As transport may occur via downward movement of porewaters and/or groundwaters. Preliminary evidence for this was found in the form of iron flocculates enriched in As which were found in surface seeps downgradient of the dam. The possibility of As remobilization and/or off-site transport by seasonal anoxia of lake bottom- waters was also explored. Although historically, appreciable As was found in the water column of the lake (up to approximately 200 micrograms/L), As releases over the summers of 2007 and 2008 were negligible to modest with a maximum [As] of 23 micrograms/L. Arsenic mobilization from the contaminated sediments into surface waters of the reservoir are limited in part due to incomplete eutrophication and frequent overturning (approximately 1x/month in summer 2007) of this shallow lake, therefore conditions which promoted greater As release were explored in the laboratory. Field and laboratory samples were examined for changes in the microbial community using a variety of genetic techniques; these changes in microbial community were both a result of, and influenced, seasonal lake cycles.

Methanogenic biodegradation of creosote contaminants in natural and simulated ground-water ecosystems

USGS Publications Warehouse

Godsy, E. Michael; Goerlitz, Donald; Grbic-Galic, Dunja

1992-01-01

Wastes from a wood preserving plant in Pensacola, Florida have contaminated the near-surface sand-and-gravel aquifer with creosote-derived compounds and pentachlorophenol. Contamination resulted from the discharge of plant waste waters to and subsequent seepage from unlined surface impoundments that were in direct hydraulic contact with the ground water. Two distinct phases resulted when the creosote and water mixed: a denser than water hydrocarbon phase that moved vertically downward, and an organic-rich aqueous phase that moved laterally with the ground-water flow. The aqueous phase is enriched in organic acids, phenolic compounds, single- and double-ring nitrogen, sulfur, and oxygen containing compounds, and single- and double-ring aromatic hydrocarbons. The ground water is devoid of dissolved O2, is 60-70% saturated with CH4 and contains H2S. Field analyses document a greater decrease in concentration of organic fatty acids, benzoic acid, phenol, 2-, 3-, 4-methylphenol, quinoline, isoquinoline, 1(2H)-quinolinone, and 2(1H)-isoquinolinone during downgradient movement in the aquifer than could be explained by dilution and/or dispersion. Laboratory microcosm studies have shown that within the study region, this effect can be attributed to microbial degradation to CH4 and CO2. A small but active methanogenic population was found on sediment materials taken from highly contaminated parts of the aquifer.

Transport and transformations of chlorinated-solvent contamination in a saprolite and fractured rock aquifer near a former wastewater-treatment plant, Greenville, South Carolina

USGS Publications Warehouse

Vroblesky, D.A.; Bradley, P.M.; Lane, J.W.; Robertson, J.F.

1997-01-01

The transport and fate of chlorinated-ethene contamination was investigated in a fractured-rock aquifer downgradient from a wastewater-treatment plant at a gas-turbine manufacturing facility in Greenville, South Carolina. A vapor-diffusion-sampler technique, developed for this investigation, located fracture zones that discharged contaminated ground water to surface water. The distribution of chlorinated compounds and sulfate, comparison of borehole geophysical data, driller's logs, and the aquifer response to pumpage allowed subsurface contaminant-transport pathways to be delineated.The probable contaminant-transport pathway from the former aeration lagoon was southward. The probable pathway of contaminant transport from the former sludge lagoon was southward to and beneath Little Rocky Creek. South of the creek, the major pathway of contaminant transport appeared to be at a depth of approximately 80 to 107 feet below land surface. The contaminant-transport pathway from the former industrial lagoon was not readily discernible from existing data. A laboratory investigation, as well as examination of ground- water-chemistry data collected during this investigation and concentrations of chlorinated compounds collected during previous investigations,indicates that higher chlorinated compounds are being degraded to lower-chlorinated compounds in the contaminated aquifer. The approaches used in this investigation, as well as the findings, have potential application to other fractured-rock aquifers contaminated by chlorinated ethenes.

Hydrogeologic reconnaissance of the Swope Oil Superfund site and vicinity, Camden and Burlington counties, New Jersey

USGS Publications Warehouse

Barton, G.J.; Krebs, M.M.

1990-01-01

Groundwater beneath a former chemical reclamation facility in New Jersey is contaminated with metals and organic compounds. The off-site migration of these compounds has not been studied; however, a nearby public-supply well is contaminated, and a public-supply well 1,400 ft downgradient from the site may be threatened. The study area, in the New Jersey part of the Atlantic Coastal Plain, is underlain by alluvial deposits composed of gravel, sand, silt, and clay. These deposits comprise the water table aquifer, the confining units, and the confined aquifer throughout the study area. The water table beneath the Swope Oil Superfund site is approximately 17 ft below sea level and groundwater levels throughout the study area are below the stage of the Delaware River. The aquifer system is recharged by precipitation, leakage of water through confining units, and the water induced from the Delaware River. Five public supply-well fields, primarily adjacent to the Delaware River, and four waste disposal sites with observation well networks are located in the study area. Both the water table and confined aquifers are contaminated in several locations. The concentration of metals and/or purgeable organic compounds in more than 20 wells exceeds the U.S. Environmental Protection Agency primary drinking-water standard and the New Jersey Department of Environmental Protection recommended drinking water criteria. Selected data from wells and test borings are presented, including well construction details; drillers ', geologists ', and geophysical logs; water levels; specific-capacity and slug test data; and chemical analysis of groundwater samples. (USGS)

Parameter-Adaptive Model-Following for In-Flight Simulation.

DTIC Science & Technology

1987-12-01

simulation architechture through the use of "smart" simulation cockpits for increased simulation capability and fidelity. Most recently, he has been...OF REPORT Approved for public release; U Lribution2b. DECLASSIFICATiON/DOWNGRADiNG SCHEDULE unlimited. 4. PERFORMING ORGANIZATION REPORT NUMBER(S) 5...MONiTOR!NG ORGANIZATICN REPORT NUMBER(S, AFIT/GE/ENG/87D-74 6a. NAME OF PERFORMING ORGANIZATION 6b. OFFICE SYMBOL 7a. NAME OF MONITORING ORGANIZATION

Response curves for phosphorus plume lengths from reactive-solute-transport simulations of onland disposal of wastewater in noncarbonate sand and gravel aquifers

USGS Publications Warehouse

Colman, John A.

2005-01-01

Surface-water resources in Massachusetts often are affected by eutrophication, excessive plant growth, which has resulted in impaired use for a majority of the freshwater ponds and lakes and a substantial number of river-miles in the State. Because supply of phosphorus usually is limiting to plant growth in freshwater systems, control of phosphorus input to surface waters is critical to solving the impairment problem. Wastewater is a substantial source of phosphorus for surface water, and removal of phosphorus before disposal may be necessary. Wastewater disposed onland by infiltration loses phosphorus from the dissolved phase during transport through the subsurface and may be an effective disposal method; quantification of the phosphorus loss can be simulated to determine disposal feasibility. In 2003, the U.S. Geological Survey, in cooperation with the Massachusetts Department of Environmental Protection, initiated a project to simulate distance of phosphorus transport in the subsurface for plausible conditions of onland wastewater disposal and subsurface properties. A coupled one-dimensional unsaturated-zone and three-dimensional saturated-zone reactive-solute-transport model (PHAST) was used to simulate lengths of phosphorus plumes. Knowledge of phosphorus plume length could facilitate estimates of setback distances for wastewater-infiltration sites from surface water that would be sufficient to protect the surface water from eutrophication caused by phosphorus transport through the subsurface and ultimate discharge to surface water. The reactive-solute-transport model PHAST was used to simulate ground-water flow, solute transport, equilibrium chemistry for dissolved and sorbed species, and kinetic regulation of organic carbon decomposition and phosphate mineral formation. The phosphorus plume length was defined for the simulations as the maximum extent of the contour for the 0.015 milligram-per-liter concentration of dissolved phosphorus downgradient from the infiltration bed after disposal cessation. Duration of disposal before cessation was assumed to be 50 years into an infiltration bed of 20,000 square feet at the rate of 3 gallons per square foot per day. Time for the maximum extent of the phosphorus plume to develop is on the order of 100 years after disposal cessation. Simulations indicated that phosphorus transport beyond the extent of the 0.015 milligram-per-liter concentration contour was never more than 0.18 kilogram per year, an amount that would likely not alter the ecology of most surface water. Simulations of phosphorus plume lengths were summarized in a series of response curves. Simulated plume lengths ranged from 200 feet for low phosphorus-concentration effluents (0.25 milligram per liter) and thick (50 feet) unsaturated zones to 3,400 feet for high phosphorus-concentration effluents (14 milligrams per liter) discharged directly into the aquifer (unsaturated-zone thickness of 0 feet). Plume length was nearly independent of unsaturated-zone thickness at phosphorus concentrations in the wastewater that were less than 2 milligrams per liter because little or no phosphorus mineral formed at low phosphorus concentrations. For effluents of high phosphorus concentration, plume length varied from 3,400 feet for unsaturated-zone thickness of 0 to 2,550 feet for unsaturated-zone thickness of 50 feet. Model treatments of flow and equilibrium-controlled chemistry likely were more accurate than rates of kinetically controlled reactions, notably precipitation of iron-phosphate minerals; the kinetics of such reactions are less well known and thus less well defined in the model. Sensitivity analysis indicated that many chemical and physical aquifer properties, such as hydraulic gradient and model width, did not affect the simulated plume length appreciably, but duration of discharge, size of infiltration bed, amount of dispersion, and number of sorption sites on the aquifer sediments did affect plume length ap

Transport and fate of nitrate and pesticides: Hydrogeology and riparian zone processes

USGS Publications Warehouse

Puckett, L.J.; Hughes, W.B.

2005-01-01

There is continuing concern over potential impacts of widespread application of nutrients and pesticides on ground- and surface-water quality. Transport and fate of nitrate and pesticides were investigated in a shallow aquifer and adjacent stream, Cow Castle Creek, in Orangeburg County, South Carolina. Pesticide and pesticide degradate concentrations were detected in ground water with greatest frequency and largest concentrations directly beneath and downgradient from the corn (Zea mays L.) field where they were applied. In almost all samples in which they were detected, concentrations of pesticide degradates greatly exceeded those of parent compounds, and were still present in ground waters that were recharged during the previous 18 yr. The absence of both parent and degradate compounds in samples collected from deeper in the aquifer suggests that this persistence is limited or that the ground water had recharged before use of the pesticide. Concentrations of NO3- in ground water decreased with increasing depth and age, but denitrification was not a dominant controlling factor. Hydrologic and chemical data indicated that ground water discharges to the creek and chemical exchange takes place within the upper 0.7 m of the streambed. Ground water had its greatest influence on surface-water chemistry during low-flow periods, causing a decrease in concentrations of Cl-, NO3-, pesticides, and pesticide degradates. Conversely, shallow subsurface drainage dominates stream chemistry during high-flow periods, increasing stream concentrations of Cl-, NO3-, pesticides, and pesticide degradates. These results point out the importance of understanding the hydrogeologic setting when investigating transport and fate of contaminants in ground water and surface water. ?? ASA, CSSA, SSSA.

Modeling the influence of variable pH on the transport of zinc in a contaminated aquifer using semiempirical surface complexation models

USGS Publications Warehouse

Kent, D.B.; Abrams, R.H.; Davis, J.A.; Coston, J.A.; LeBlanc, D.R.

2000-01-01

Land disposal of sewage effluent resulted in contamination of a sand and gravel aquifer (Cape Cod, Massachusetts) with zinc (Zn). The distribution of Zn was controlled by pH‐dependent adsorption; the Zn extended 15 m into the 30‐m‐thick sewage plume within approximately 100 m of the source but only 2–4 m into the plume between 100 and 400 m downgradient. A two‐dimensional vertical cross section model coupling groundwater flow with solute transport and equilibrium adsorption is used to simulate the influence of pH on Zn transport. Adsorption is described using semiempirical surface complexation models (SCM) by writing chemical reactions between dissolved Zn and mineral surface sites. SCM parameters were determined in independent laboratory experiments. A 59‐year simulation with a one‐site SCM describes the influence of pH on Zn transport well, with greater mobility at the low pH values near the upper sewage plume boundary than at the higher pH values deeper in the sewage‐contaminated zone. Simulation with a two‐site SCM describes both the sharpness and approximate location of the leading edge of the Zn‐contaminated region. Temporal variations in pH of incoming groundwater can result in large increases in Zn concentration and mobility. The influence of spatial and temporal variability in pH on adsorption and transport of Zn was accomplished much more easily with the semiempirical SCM approach than could be achieved with distribution coefficients or adsorption isotherms.

Chemical quality of ground water in Salt Lake Valley, Utah, 1969-85

USGS Publications Warehouse

Waddell, K.M.; Seiler, R.L.; Solomon, D.K.

1986-01-01

During 1979-84, 35 wells completed in the principal aquifer in the Salt Lake Valley, Utah, that had been sampled during 1962-67 were resampled to determine if water quality changes had occurred. The dissolved solids concentration of the water from 13 of the wells has increased by more than 10% since 1962-67. Much of the ground water between the mouth of Bingham Canyon and the Jordan River about 10 mi to the east has been contaminated by seepage from reservoirs and evaporation ponds associated with mining activities. Many domestic and irrigation wells yield water with concentrations of dissolved solids that exceed 2,000 mg/L. A reservoir in the mouth of Bingham Canyon contains acidic waters with a pH of 3 to 4 and concentrations of dissolved solids ranging from 43,000 to 68,000 mg/L. Seepage from evaporation ponds, which are about 4.5 mi east of the reservoir, also is acidic and contains similar concentrations of dissolved solids. East of the reservoir, where a steep hydraulic gradient exists along the mountain front, the velocities of contaminant movement were estimated to range from about 680-1,000 ft/yr. Groundwater underlying part of the community of South Salt Lake near the Jordan River has been contaminated by leachate from uranium-mill tailings. The major effect of the leachate from the tailings of the Vitro Chemical Co. on the shallow unconfined aquifer downgradient from the tailings was the contribution of measurable quantities of dissolved solids, chloride, sulfate, iron, and uranium. The concentration of dissolved solids in uncontaminated water was 1,650 mg/L, whereas downgradient from the tailings area, the concentrations ranged from 2,320-21,000 mg/L. The maximum volume of contaminated water was estimated to be 7,800 acre-ft. The major effect of the leachate from the Vitro tailings on the confined aquifer was the contribution of measurable quantities of dissolved solids, chloride, sulfate, and iron. The concentration of dissolved solids upgradient from the tailings was 330 mg/L, and beneath and downgradient from the tailings the concentrations were 864 and 1,240 mg/L. The minimum volume of contaminated water in the confined aquifer was estimated to be about 12,000 acre-ft. (Lantz-PTT)

Digital modeling of radioactive and chemical waste transport in the aquifer underlying the Snake River Plain at the National Reactor Testing Station, Idaho

USGS Publications Warehouse

Robertson, J.B.

1974-01-01

Industrial and low-level radioactive liquid wastes at the National Reactor Testing Station (NRTS) in Idaho have been disposed to the Snake River Plain aquifer since 1952. Monitoring studies have indicated that tritium and chloride have dispersed over a 15-square mile (39-square kilometer) area of the aquifer in low but detectable concentrations and have only migrated as far as 5 miles (8 kilometers) downgradient from discharge points. The movement of cationic waste solutes, particularly 90Sr and 137Cs, has been significantly retarded due to sorption phenomena, principally ion exchange. 137Cs has shown no detectable migration in the aquifer and 90Sr has migrated only about 1.5 miles (2 kilometers) from the Idaho Chemical Processing Plant (ICPP) discharge well, and is detectable over an area of only 1.5 square miles ( 4 square kilometers) of the aquifer. Digital modeling techniques have been applied successfully to the analysis of the complex waste-transport system by utilizing numerical solution of the coupled equations of groundwater motion and mass transport. The model includes the effects of convective transport, flow divergence, two-dimensional hydraulic dispersion, radioactive decay, and reversible linear sorption. The hydraulic phase of the model uses the iterative, alternating direction, implicit finite-difference scheme to solve the groundwater flow equations, while the waste-transport phase uses a modified method of characteristics to solve the solute transport equations simulated by the model. The modeling results indicate that hydraulic dispersion (especially transverse) is a much more significant influence than previously suggested by earlier studies. The model has been used to estimate future waste migration patterns for varied assumed hydrological and waste conditions up through the year 2000. The hydraulic effects of recharge from the Big Lost River have an important (but not predominant) influence on the simulated future migration patterns. For the assumed conditions, the model indicates that detectable concentrations of waste chloride and tritium could move as much as 15 miles (24 kilometers) downgradient from the original discharge points by the year 2000. However, the model shows 90Sr moving only 2 to 3 miles (3 to 5 kilometers) downgradient in the same time. The model may also be used to estimate the effects of the various future waste disposal practices and hydrologic conditions on subsequent migration of waste products.

Long-term groundwater contamination after source removal—The role of sorbed carbon and nitrogen on the rate of reoxygenation of a treated-wastewater plume on Cape Cod, MA, USA

USGS Publications Warehouse

Smith, Richard L.; Repert, Deborah A.; Barber, Larry B.; LeBlanc, Denis R.

2013-01-01

The consequences of groundwater contamination can remain long after a contaminant source has been removed. Documentation of natural aquifer recoveries and empirical tools to predict recovery time frames and associated geochemical changes are generally lacking. This study characterized the long-term natural attenuation of a groundwater contaminant plume in a sand and gravel aquifer on Cape Cod, Massachusetts, after the removal of the treated-wastewater source. Although concentrations of dissolved organic carbon (DOC) and other soluble constituents have decreased substantially in the 15 years since the source was removed, the core of the plume remains anoxic and has sharp redox gradients and elevated concentrations of nitrate and ammonium. Aquifer sediment was collected from near the former disposal site at several points in time and space along a 0.5-km-long transect extending downgradient from the disposal site and analyses of the sediment was correlated with changes in plume composition. Total sediment carbon content was generally low (< 8 to 55.8 μmol (g dry wt)− 1) but was positively correlated with oxygen consumption rates in laboratory incubations, which ranged from 11.6 to 44.7 nmol (g dry wt)− 1 day− 1. Total water extractable organic carbon was < 10–50% of the total carbon content but was the most biodegradable portion of the carbon pool. Carbon/nitrogen (C/N) ratios in the extracts increased more than 10-fold with time, suggesting that organic carbon degradation and oxygen consumption could become N-limited as the sorbed C and dissolved inorganic nitrogen (DIN) pools produced by the degradation separate with time by differential transport. A 1-D model using total degradable organic carbon values was constructed to simulate oxygen consumption and transport and calibrated by using observed temporal changes in oxygen concentrations at selected wells. The simulated travel velocity of the oxygen gradient was 5–13% of the groundwater velocity. This suggests that the total sorbed carbon pool is large relative to the rate of oxygen entrainment and will be impacting groundwater geochemistry for many decades. This has implications for long-term oxidation of reduced constituents, such as ammonium, that are being transported downgradient away from the infiltration beds toward surface and coastal discharge zones.

Hydrogeology and water quality near a solid- and hazardous-waste landfill, Northwood, Ohio

USGS Publications Warehouse

De Roche, J.T.; Breen, K.J.

1989-01-01

Hydrogeology and water quality of ground water and selected streams were evaluated near a landfill in northwestern Ohio. The landfill is used for codisposal of solid and hazardous waste. Water-level and geologic data were collected from 36 wells and 3 surface-water sites during the period November 1983 to November 1985. Water-quality samples were collected from 18 wells and 3 surface-water sites this during this same period. The primary aquifers in the area are the Greenfield Dolomite and underlying Lockport Dolomite of Silurian age. These bedrock carbonates are overlain by two clay tills of Wisconsin age. The tills are capped by a glacial lake clay. The tills generally are saturated, but do not yield sufficient water to be considered an aquifer. Two wells in the study area yield water, in part, from discontinuous deposits of outwash sand and gravel at the lower till-bedrock interface. Regional ground-water flow is from southwest to northeast; local flow is influenced by a ground-water mound centered under the northernmost cells of the landfill. Water levels in wells penetrating refuse within the landfill and the presence of leachate seeps indicate that the refuse is saturated. Head relations among the landfill, till, and dolomite aquifer indicate a vertical component of flow downward from the landfill to the dolomite aquifer. Water levels near the landfill fluctuate as much as 14 feet per year, in contrast to fluctuations of less than 3 feet per year in wells upgradient landfill. Ground waters from wells completed in the dolomite aquifer and glacial till were found to have major-iron concentrations controlled, in large part, by reaction with calcite, dolomite, and other minerals in the aquifer. Only minor departures from equilibrium mineral saturation were noted for ground water, except in wells affected by cement/grout contamination. Molal ratios of calcuim:magnesium in ground water suggest a similar chemical evolution of waters throughout the dolomite aquifer in the study area. Stable-isotope ratios of oxygen and hydrogen indicate the source of water in the till unit and dolomite aquifer is atmospheric precipitation. Elevated levels of total dissolved solids, boron, ammonia, and iron in the leachate and in wells downgradient of the landfill may indicate mixing of ground water with leachate. Oxygen and hydrogen stable-isotope ratios were used to differentiate waters from the glacial till and dolomite aquifer. Isotope ratios also show a shift off the local mixing line for leachate and for a well just downgradient from the landfill. The shift to heavier values of o D in the well water may be indicative of leachate mixing with ground water. The effect of this mixing denoted by hydrologic, isotopic, and chemical-quality data is limited mostly to elevated levels of the common ions. Analysis did not indicate significant levels of toxic metals or organic contaminants except phenol, which was present at concentrations of from 1 to 5 micrograms per liter in six wells. Analysis of water-quality data from nearby streams suggest that surface leaching from the landfill does not significantly affect stream-water quality, but may contribute to higher level of trace metals in the streambed sediments.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

1996-03-01

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

Connecting the Dots: Hydrologic Connectivity Between ...

EPA Pesticide Factsheets

Wetlands perform numerous ecosystem functions that in turn provide abundant ecosystem services beneficial to humankind. These may include, but are not limited to, flood water storage and release, nutrient transformations, carbon sequestration, and the provision of habitat or refugia. The importance of wetland effects on downgradient waters, such as other wetlands or streams, lies in the degree to which they are hydrologically connected or disconnected across the landscape. Featured article on the emerging science of aquatic system connectivity.

Geology, hydrology, and water quality of the glacial drift aquifer in the vicinity of the Nelson landfill near Yorkville, Illinois

USGS Publications Warehouse

Kay, Robert T.

2006-01-01

The geologic and hydrologic characteristics of the sand-and-gravel deposits that compose the glacial drift aquifer in the vicinity of the Nelson Landfill site in Yor-kville, Illinois indicate that the aquifer could be devel-oped as a source of public water supply. The geology of these deposits within the Newark Bedrock Valley is com-plex, however, and a detailed investigation of their water bearing and transmitting properties will be required to successfully locate high-capacity wells. Volatile organic compounds, pesticides, and cyanide were not detected in ground water during this investiga-tion. Metals and nitrogen compounds were not detected at concentrations above their Maximum Contaminant Level. Iron, manganese, and aluminum were detected at concentrations above their Secondary Maximum Con-taminant Level and various constituents were detected at concentrations above background levels downgradi-ent of the landfill. Nitrate and ammonia, presumably derived from agricultural practices, also were detected in samples from locations hydraulically upgradient of the landfill. Oxidation-reduction conditions in the aquifer become more reducing with depth. This change is reflected by a change in the type of nitrogen compound detected and the concentration of dissolved oxygen and iron in the glacial drift aquifer. Concentrations of some of the major ions and metals may be affected by disso-lution of carbonate minerals in the aquifer and perhaps road salts.

Denitrification in a Sand and Gravel Aquifer

PubMed Central

Smith, Richard L.; Duff, John H.

1988-01-01

Denitrification was assayed by the acetylene blockage technique in slurried core material obtained from a freshwater sand and gravel aquifer. The aquifer, which has been contaminated with treated sewage for more than 50 years, had a contaminant plume greater than 3.5-km long. Near the contaminant source, groundwater nitrate concentrations were greater than 1 mM, whereas 0.25 km downgradient the central portion of the contaminant plume was anoxic and contained no detectable nitrate. Samples were obtained along the longitudinal axis of the plume (0 to 0.25 km) at several depths from four sites. Denitrification was evident at in situ nitrate concentrations at all sites tested; rates ranged from 2.3 to 260 pmol of N2O produced (g of wet sediment)−1 h−1. Rates were highest nearest the contaminant source and decreased with increasing distance downgradient. Denitrification was the predominant nitrate-reducing activity; no evidence was found for nitrate reduction to ammonium at any site. Denitrifying activity was carbon limited and not nitrate limited, except when the ambient nitrate level was less than the detection limit, in which case, even when amended with high concentrations of glucose and nitrate, the capacity to denitrify on a short-term basis was lacking. These results demonstrate that denitrification can occur in groundwater systems and, thereby, serve as a mechanism for nitrate removal from groundwater. PMID:16347621

Se Isotopes as groundwater redox indicators: Detecting natural attenuation of Se at an in situ recovery U mine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anirban, Basu; Schilling, Kathrin; Brown, Shaun T.

One of the major ecological concerns associated with the in situ recovery (ISR) of uranium (U) is the environmental release of soluble, toxic selenium (Se) oxyanions generated by mining. Post-mining natural attenuation by the residual reductants in the ore body and reduced down-gradient sediments should mitigate the risk of Se contamination in groundwater. Here in this work, we investigate the Se concentrations and Se isotope systematics of groundwater and of U ore bearing sediments from an ISR site at Rosita, TX, USA. Our results show that selenate (Se(VI)) is the dominant Se species in Rosita groundwater, and while several up-gradientmore » wells have elevated Se(VI), the majority of the ore zone and down-gradient wells have little or no Se oxyanions. In addition, the δ 82SeVI of Rosita groundwater is generally elevated relative to the U ore up to +6.14‰, with the most enriched values observed in the ore-zone wells. Increasing δ 82Se with decreasing Se(VI) conforms to a Rayleigh type distillation model with an ε of $-$2.25‰ ± 0.61‰, suggesting natural Se(VI) reduction occurring along the hydraulic gradient at the Rosita ISR site. Moreover, our results show that Se isotopes are excellent sensors for detecting and monitoring post-mining natural attenuation of Se oxyanions at ISR sites.« less

CARBON-BASED REACTIVE BARRIER FOR NITRATE ...

EPA Pesticide Factsheets

Nitrate (NO3-) is a common ground water contaminant related to agricultural activity, waste water disposal, leachate from landfills, septic systems, and industrial processes. This study reports on the performance of a carbon-based permeable reactive barrier (PRB) that was constructed for in-situ bioremediation of a ground water nitrate plume caused by leakage from a swine CAFO (concentrated animal feeding operation) lagoon. The swine CAFO, located in Logan County, Oklahoma, was in operation from 1992-1999. The overall site remediation strategy includes an ammonia recovery trench to intercept ammonia-contaminated ground water and a hay straw PRB which is used to intercept a nitrate plume caused by nitrification of sorbed ammonia. The PRB extends approximately 260 m to intercept the nitrate plume. The depth of the trench averages 6 m and corresponds to the thickness of the surficial saturated zone; the width of the trench is 1.2 m. Detailed quarterly monitoring of the PRB began in March, 2004, about 1 year after construction activities ended. Nitrate concentrations hydraulically upgradient of the PRB have ranged from 23 to 77 mg/L N, from 0 to 3.2 mg/L N in the PRB, and from 0 to 65 mg/L N hydraulically downgradient of the PRB. Nitrate concentrations have generally decreased in downgradient locations with successive monitoring events. Mass balance considerations indicate that nitrate attenuation is dominantly from denitrification but with some component of

Does Disposing of Construction and Demolition Debris in Unlined Landfills Impact Groundwater Quality? Evidence from 91 Landfill Sites in Florida.

PubMed

Powell, Jon T; Jain, Pradeep; Smith, Justin; Townsend, Timothy G; Tolaymat, Thabet M

2015-08-04

More than 1,500 construction and demolition debris (CDD) landfills operate in the United States (U.S.), and U.S. federal regulations do not require containment features such as low-permeability liners and leachate collection systems for these facilities. Here we evaluate groundwater quality from samples collected in groundwater monitoring networks at 91 unlined, permitted CDD landfills in Florida, U.S. A total of 460,504 groundwater sample results were analyzed, with a median of 10 years of quarterly or semiannual monitoring data per site including more than 400 different chemical constituents. Downgradient concentrations of total dissolved solids, sulfate, chloride, iron, ammonia-nitrogen, and aluminum were greater than upgradient concentrations (p < 0.05). At downgradient wells where sulfate concentrations were greater than 150 mg/L (approximately 10% of the maximum dissolved sulfate concentration in water, which suggests the presence of leachate from the landfill), iron and arsenic were detected in 91% and 43% of samples, with median concentrations of 1,900 μg/L and 11 μg/L, respectively. These results show that although health-based standards can be exceeded at unlined CDD landfills, the magnitude of detected chemical concentrations is generally small and reflective of leached minerals from components (wood, concrete, and gypsum drywall) that comprise the bulk of discarded CDD by mass.

Se Isotopes as groundwater redox indicators: Detecting natural attenuation of Se at an in situ recovery U mine

DOE PAGES

Anirban, Basu; Schilling, Kathrin; Brown, Shaun T.; ...

2016-08-22

One of the major ecological concerns associated with the in situ recovery (ISR) of uranium (U) is the environmental release of soluble, toxic selenium (Se) oxyanions generated by mining. Post-mining natural attenuation by the residual reductants in the ore body and reduced down-gradient sediments should mitigate the risk of Se contamination in groundwater. Here in this work, we investigate the Se concentrations and Se isotope systematics of groundwater and of U ore bearing sediments from an ISR site at Rosita, TX, USA. Our results show that selenate (Se(VI)) is the dominant Se species in Rosita groundwater, and while several up-gradientmore » wells have elevated Se(VI), the majority of the ore zone and down-gradient wells have little or no Se oxyanions. In addition, the δ 82SeVI of Rosita groundwater is generally elevated relative to the U ore up to +6.14‰, with the most enriched values observed in the ore-zone wells. Increasing δ 82Se with decreasing Se(VI) conforms to a Rayleigh type distillation model with an ε of $-$2.25‰ ± 0.61‰, suggesting natural Se(VI) reduction occurring along the hydraulic gradient at the Rosita ISR site. Moreover, our results show that Se isotopes are excellent sensors for detecting and monitoring post-mining natural attenuation of Se oxyanions at ISR sites.« less

Impact of a medical waste incinerator on mercury levels in lagoon fish from a small tropical island in the Western Pacific.

PubMed

Denton, Gary R W; Trianni, Michael S; Bearden, Brian G; Houk, Peter C; Starmer, John A

2011-01-01

In 2004-2005, several species of marine fish were collected for mercury (Hg) analysis from Saipan Lagoon, Saipan, Commonwealth of the Northern Mariana Islands. Relatively high concentrations were found in representatives from the Hafa Adai Beach area located some distance from known sources of Hg contamination. A follow-up investigation aimed at identifying additional land-based sources of Hg in the area was launched in early 2007. The study identified a medical waste incinerator as the primary source of Hg enrichment. The incinerator was operational for about 20 years before it was closed down by the U.S. Environmental Protection Agency (EPA) in January 2006, for multiple violations of the Clean Air Act. Stormwater runoff from this facility entered a drainage network that discharged into the ocean at the southern end of Hafa Adai Beach, about 1 km away. At the time of this investigation storm drain sediments at the coast were only marginally enriched with mercury although values some 50x above background were detected in drainage deposits a few meters down-gradient of the incinerator site. Mercury concentrations in fish from the Hafa Adai Beach area were also significantly lower than those determined in similar species 3 yr earlier. The implications of the data are briefly discussed.

Organic Wastewater Compounds, Pharmaceuticals, andColiphage in Ground Water Receiving Discharge from OnsiteWastewater Treatment Systems near La Pine, Oregon:Occurrence and Implications for Transport

USGS Publications Warehouse

Hinkle, Stephen J.; Weick, Rodney J.; Johnson, Jill M.; Cahill, Jeffery D.; Smith, Steven G.; Rich, Barbara J.

2005-01-01

The occurrence of organic wastewater compounds (components of 'personal care products' and other common household chemicals), pharmaceuticals (human prescription and nonprescription medical drugs), and coliphage (viruses that infect coliform bacteria, and found in high concentrations in municipal wastewater) in onsite wastewater (septic tank effluent) and in a shallow, unconfined, sandy aquifer that serves as the primary source of drinking water for most residents near La Pine, Oregon, was documented. Samples from two types of observation networks provided basic occurrence data for onsite wastewater and downgradient ground water. One observation network was a group of 28 traditional and innovative (advanced treatment) onsite wastewater treatment systems and associated downgradient drainfield monitoring wells, referred to as the 'innovative systems network'. The drainfield monitoring wells were located adjacent to or under onsite wastewater treatment system drainfield lines. Another observation network, termed the 'transect network', consisted of 31 wells distributed among three transects of temporary, stainless-steel-screened, direct-push monitoring wells installed along three plumes of onsite wastewater. The transect network, by virtue of its design, also provided a basis for increased understanding of the transport of analytes in natural systems. Coliphage were frequently detected in onsite wastewater. Coliphage concentrations in onsite wastewater were highly variable, ranging from less than 1 to 3,000,000 plaque forming units per 100 milliliters. Coliphage were occasionally detected (eight occurrences) at low concentrations in samples from wells located downgradient from onsite wastewater treatment system drainfield lines. However, coliphage concentrations were below method detection limits in replicate or repeat samples collected from the eight sites. The consistent absence of coliphage detections in the replicate or repeat samples is interpreted to indicate that the detections reported for ground-water samples represented low-level field or laboratory contamination, and it would appear that coliphage were effectively attenuated to less than 1 PFU/100 mL over distances of several feet of transport in the La Pine aquifer and (or) overlying unsaturated zone. Organic wastewater compounds were frequently detected in onsite wastewater. Of the 63 organic wastewater compounds in the analytical schedule, 45 were detected in the 21 samples of onsite wastewater. Concentrations of organic wastewater compounds reached a maximum of 1,300 ug/L (p-cresol). Caffeine was detected at concentrations as high as 320 ug/L. Fourteen of the 45 compounds were detected in more than 90 percent of onsite wastewater samples. Fewer (nine) organic wastewater compounds were detected in ground water, despite the presence of nitrate and chloride likely from onsite wastewater sources. The nine organic wastewater compounds that were detected in ground-water samples were acetyl-hexamethyl-tetrahydro-naphthalene (AHTN), caffeine, cholesterol, hexahydrohexamethyl-cyclopentabenzopyran, N,N-diethyl-meta-toluamide (DEET), tetrachloroethene, tris (2-chloroethyl) phosphate, tris (dichloroisopropyl) phosphate, and tributyl phosphate. Frequent detection of household-chemical type organic wastewater compounds in onsite wastewater provides evidence that some of these organic wastewater compounds may be useful indicators of human waste effluent dispersal in some hydrologic environments. The occurrence of organic wastewater compounds in ground water downgradient from onsite wastewater treatment systems demonstrates that a subgroup of organic wastewater compounds is transported in the La Pine aquifer. The consistently low concentrations (generally less than 1 ug/L) of organic wastewater compounds in water samples collected from wells located no more than 19 feet from drainfield lines indicates that the reactivity (sorption, degradation) of this suite of organic waste

Dissolved Organic Carbon 14C in Southern Nevada Groundwater and Implications for Groundwater Travel Times

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hershey, Ronald L.; Fereday, Wyall; Thomas, James M

Dissolved inorganic carbon (DIC) carbon-14 ( 14C) ages must be corrected for complex chemical and physical reactions and processes that change the amount of 14C in groundwater as it flows from recharge to downgradient areas. Because of these reactions, DIC 14C can produce unrealistically old ages and long groundwater travel times that may, or may not, agree with travel times estimated by other methods. Dissolved organic carbon (DOC) 14C ages are often younger than DIC 14C ages because there are few chemical reactions or physical processes that change the amount of DOC 14C in groundwater. However, there are several issuesmore » that create uncertainty in DOC 14C groundwater ages including limited knowledge of the initial (A 0) DOC 14C in groundwater recharge and potential changes in DOC composition as water moves through an aquifer. This study examines these issues by quantifying A 0 DOC 14C in recharge areas of southern Nevada groundwater flow systems and by evaluating changes in DOC composition as water flows from recharge areas to downgradient areas. The effect of these processes on DOC 14C groundwater ages is evaluated and DOC and DIC 14C ages are then compared along several southern Nevada groundwater flow paths. Twenty-seven groundwater samples were collected from springs and wells in southern Nevada in upgradient, midgradient, and downgradient locations. DOC 14C for upgradient samples ranged from 96 to 120 percent modern carbon (pmc) with an average of 106 pmc, verifying modern DOC 14C ages in recharge areas, which decreases uncertainty in DOC 14C A 0 values, groundwater ages, and travel times. The HPLC spectra of groundwater along a flow path in the Spring Mountains show the same general pattern indicating that the DOC compound composition does not change along this flow path. Although DOC concentration decreases from recharge-area to downgradient groundwater, the organic compounds are similar, indicating that DOC 14C is unaffected by other processes such as microbial degradation. A small amount of organic carbon was leached from crushed volcanic and carbonate aquifer outcrop rock in rock-leaching experiments. The leached DOC was high in 14C (75 pmc carbonate rocks, 91 pmc volcanic) suggesting that the leached DOC likely came from microbes in the rock samples. The small amount of DOC and high 14C indicates that the amount of old organic carbon in these rocks is low so there should be minimal impact on groundwater DOC 14C ages. Based on the results from this study, DOC 14C ages do not require additional corrections. Several correction models were applied to DIC 14C ages to correct for water-rock reactions along two carbonate and two volcanic flow paths and the corresponding travel times were compare to DOC 14C travel times. The DOC 14C travel times were hundreds to thousands of years shorter than uncorrected and corrected DIC 14C travel times except for the upper section of one carbonate flow path. DOC 14C travel times ranged from 400 to 5,400 years as compared to DIC 14C that ranged from modern to 20,900 years. The DIC 14C ages are greatly influenced by carbonate mineral and gas reactions and other processes such as matrix diffusion, isotope exchange, or adsorption, which are not always adequately accounted for in DIC 14C groundwater age correction models.« less

Remedial Investigation Report Area of Contamination (AOC) 43J. Volume 1 of 2

DTIC Science & Technology

1996-02-01

produced risks within the USEPA range (1x1W05 and 3x10’, respectively). If the modified cancer slope factor (CSF) for arsenic was used to estimate excess...lifetime cancer risks for both source area and downgradient groundwater quality, then the cancer risks associated with exposure to both average and...very poorly drained; nearly level, organic; occurs in depressions and on flat areas of uplands and glacial outwash plains. Windsor Series. Deep

Groundwater and Leachate Monitoring and Sampling at ERDF, CY 2010

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weiss, R. L.; Lawrence, B. L.

2011-06-09

The purpose of this annual monitoring report is to evaluate the conditions of and identify trends for groundwater beneath the ERDF and report leachate results in fulfillment of the requirements specified in the ERDF ROD2 and the ERDF Amended ROD (EPA 1999). The overall objective of the groundwater monitoring program is to determine whether ERDF has impacted the groundwater. This objective is complicated by the fact that the ERDF is situated downgradient of the numerous groundwater contamination plumes originating from the 200 West Area.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, Raymond H.; Stone, James; Truax, Ryan

Batch tests, column tests, and predictive reactive transport modeling can be done before ISR begins as part of the decision making/permitting process by bracketing possible post-restoration conditions; Help address stakeholder concerns; The best predictions require actual restored groundwater in contact with the downgradient solid phase; Resulting modeling provides a range of natural attenuation rates and assists with designing the best locations and time frames for continued monitoring; Field pilot tests are the best field-scale data and can provide the best model input and calibration data

Installation Restoration Program. Phase II. Confirmation/Quantification. Stage 1 for Hancock Field, New York and HQTAC, Langley AFB, Virginia.

DTIC Science & Technology

1984-10-01

resulting from previous waste disposal practices at Hancock Field o Recommend measures to mitigatc, adverse impacts at identified contaminated areas o...well GW-8 is downgradient of both disposal sites and this will be the best well to use in judging water quality impacts caused by the disposal...groundwater quality and quantity samples. The amount of water added to each well was in the order of 2 to 4 gallons. This should not adversely impact

Use of chemical and isotopic tracers to characterize the interactions between ground water and surface water in mantled karst

DOE Office of Scientific and Technical Information (OSTI.GOV)

Katz, B.G.; Davis, J.H.; Coplen, T.B.

1997-11-01

In the mantled karst terrane of northern Florida, the water quality of the Upper Floridan aquifer is influenced by the degree of connectivity between the aquifer and the surface. Chemical and isotopic analyses [{sup 18}O/{sup 16}O ({delta}{sup 18}O), {sup 2}H/{sup 1}H ({delta}D), {sup 13}C/{sup 12}C ({delta}{sup 13}C), tritium ({sup 3}H), and strontium-87/strontium-86 ({sup 87}Sr/{sup 86}Sr)] along with geochemical mass-balance modeling were used to identify the dominant hydrochemical processes that control the composition of ground water as it evolves downgradient in two systems. In one system, surface water enters the Upper Florida aquifer through a sinkhole located in the Northern Highlandsmore » physiographic unit. In the other system, surface water enters the aquifer through a sinkhole lake (Lake Bradford) in the Woodville Karst Plain. Differences in the composition of water isotopes ({delta}{sup 18}O and {delta}D) in rainfall, ground water, and surface water were used to develop mixing models of surface water (leakage of water to the Upper Floridan aquifer from a sinkhole lake and a sinkhole) and ground water. Using mass-balance calculations, based on differences in {delta}{sup 18}O and {delta}D, the proportion of lake water that mixed with meteoric water ranged from 7 to 86% in water from wells located in close proximity to lake Bradford. In deeper parts of the Upper Floridan aquifer, water enriched in {sup 18}O and D from five of 12 samples municipal wells indicated that recharge from a sinkhole (1 to 24%) and surface water with an evaporated isotopic signature (2 to 32%) was mixing with ground water. The solute isotopes, {delta}{sup 13}C and {sup 87}Sr/{sup 86}Sr, were used to test the sensitivity of binary and ternary mixing models, and to estimate the amount of mass transfer of carbon and other dissolved species in geochemical reactions.« less

Filtration of Pathogenic Parasites Using Surfactant-Modified Zeolites

NASA Astrophysics Data System (ADS)

Lehner, T.; Schulze-Makuch, D.; Bowman, R.

2003-12-01

Migration of pathogenic microorganisms, specifically Cryptosporidium parvum and Giardia lamblia, in groundwater due to sewage effluent and mismanaged wastewater has become an increased concern for human health in many regions. Cryptosporididosis and Giardiasis produces moderate to severe intestinal illness for many weeks and is a serious threat for immunodeficient persons. Previous studies by Schulze-Makuch et al. (2002) indicated that surfactant-modified zeolites (SMZ) removed all of the bacteria and most viruses in laboratory experiments. This study focuses on the efficiency of the SMZ to prevent migration of the protozoan spores in groundwater. Adsorption of the spores involves interactions between the surface properties of the spores and the SMZ. The efficiency of removal is tested simulating natural conditions. Laboratory experiments are conducted in a plexiglass model aquifer and pathogen removal is measured by taking water samples from strategically placed piezometers in the model. Since C. parvum and G. lamblia are hazardous to humans and move primarily in spore state through groundwater, polystyrene microspheres of similar sizes and Bacillus subtilis, a sporulating bacterium, are used as analogues for the protozoa. Preliminary results show a significant decrease in concentration of the B. subtilis spores down-gradient of the barrier.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ross, J; Walt Kubilius, W; Thomas Kmetz, T

Resource Conservation and Recovery Act (RCRA) requirements for hazardous waste facilities include 30 years of post-closure monitoring. The use of an objective-based monitoring strategy allows for a significant reduction in the amount of groundwater monitoring required, as the groundwater remediation transitions from an active biosparging system to monitored natural attenuation. The lifecycle of groundwater activities at the landfill has progressed from detection monitoring and plume characterization, to active groundwater remediation, and now to monitored natural attenuation and postclosure monitoring. Thus, the objectives of the groundwater monitoring have changed accordingly. Characterization monitoring evaluated what biogeochemical natural attenuation processes were occurring andmore » determined that elevated levels of radium were naturally occurring. Process monitoring of the biosparging system required comprehensive sampling network up- and down-gradient of the horizontal wells to verify its effectiveness. Currently, the scope of monitoring and reporting can be significantly reduced as the objective is to demonstrate that the alternate concentration limits (ACL) are being met at the point of compliance wells and the maximum contaminant level (MCL) is being met at the surface water point of exposure. The proposed reduction is estimated to save about $2M over the course of the remaining 25 years of postclosure monitoring.« less

Performance of deep-rooted phreatophytic trees at a site containing total petroleum hydrocarbons.

PubMed

Ferro, Ari M; Adham, Tareq; Berra, Brett; Tsao, David

2013-01-01

Poplar and willow tree stands were installed in 2003 at a site in Raleigh, North Carolina containing total petroleum hydrocarbon - contaminated groundwater. The objective was groundwater uptake and plume control. The water table was 5 to 6 m below ground surface (bgs) and therefore methods were used to encourage deep root development. Growth rates, rooting depth and sap flow were measured for trees in Plot A located in the center of the plume and in Plot B peripheral to the plume. The trees were initially sub-irrigated with vertically installed drip-lines and by 2005 had roots 4 to 5 m bgs. Water balance calculations suggested groundwater uptake. In 2007, the average sap flow was higher for Plot B (approximately 59 L per day per tree) than for Plot A (approximately 23 L per day per tree), probably as a result of TPH-induced stress in Plot A. Nevertheless, the estimated rate of groundwater uptake for Plot A was sufficient, relative to the calculated rate of groundwater flux beneath the stand, that a high level of plume control was achieved based on MODFLOW modeling results. Down-gradient groundwater monitoring wells installed in late 2011 should provide quantitative data for plume control.

Onsite Wastewater System Nitrogen Contributions to Groundwater in Coastal North Carolina

PubMed Central

Humphrey, C.P.; O’Driscoll, M.A.; Deal, N.E.; Lindbo, D.L.; Thieme, S.C.; Zarate-Bermudez, M.A.

2016-01-01

The objective of the study described in this article was to evaluate the nitrogen contributions from two onsite wastewater systems (sites 1 and 2) to groundwater and adjacent surface waters in coastal Beaufort County, North Carolina. Groundwater levels and water quality parameters including total nitrogen, nitrogen species, temperature, and pH were monitored from October 2009 to May 2010. Nitrogen was also tested in groundwater from deeper irrigation or drinking water wells from the two sites and six additional neighboring residences. Mean total nitrogen concentrations in groundwater beneath onsite wastewater systems 1 and 2 were 34.3 ± 16.7 mg/L and 12.2 ± 2.9 mg/L, respectively, and significantly higher than background groundwater concentrations (<1 mg/L). Groundwater in the deeper wells appeared not to be influenced by the onsite systems. Groundwater nitrogen concentrations typically decreased with distance down-gradient from the systems, but were still elevated relative to background conditions more than 15 m from the systems and near the estuary. This was a pioneering effort to better understand the link of onsite systems, the fate of nitrogen in the environment, and public health. PMID:24437045

Pesticides in surface water, bed sediment, and ground water adjacent to commercial cranberry bogs, Lac du Flambeau Reservation, Vilas County, Wisconsin

USGS Publications Warehouse

Saad, David A.

2005-01-01

In samples from the Trout River, which is used as a source of water to maintain lake levels in the Corn Lakes, the only pesticides detected were the non-targeted compounds atrazine and deethyl atrazine, indicating it was not a source of targeted compounds detected in the Corn Lakes. Only two pesticides (chlorpyrifos and metolachlor) were detected in bed-sediment samples collected from the lakes; chlorpyrifos from Little Trout Lake and metolachlor from the Corn Lakes. Four pesticides (the targeted compounds napropamide and norflurazon and the non-targeted compounds atrazine and deethyl atrazine) were detected in ground-water samples from two of four sampled monitor wells. The highest ground-water concentrations (up to 0.14 ?g/L napropamide and 0.56 ?g/L norflurazon) were measured in samples from the monitoring well located directly downgradient from the Corn Lakes and commercial cranberry operations. No pesticides were detected in samples from the reference well located upgradient from the Corn Lakes and cranberry operations. Further study is needed to identify additional pesticides as well as chronic effects on aquatic organisms to determine whether cranberry-related pesticides affect the lake ecosystems of the Lac du Flambeau Reservation.

Coupling geophysical investigation with hydrothermal modeling to constrain the enthalpy classification of a potential geothermal resource.

USGS Publications Warehouse

White, Jeremy T.; Karakhanian, Arkadi; Connor, Chuck; Connor, Laura; Hughes, Joseph D.; Malservisi, Rocco; Wetmore, Paul

2015-01-01

An appreciable challenge in volcanology and geothermal resource development is to understand the relationships between volcanic systems and low-enthalpy geothermal resources. The enthalpy of an undeveloped geothermal resource in the Karckar region of Armenia is investigated by coupling geophysical and hydrothermal modeling. The results of 3-dimensional inversion of gravity data provide key inputs into a hydrothermal circulation model of the system and associated hot springs, which is used to evaluate possible geothermal system configurations. Hydraulic and thermal properties are specified using maximum a priori estimates. Limited constraints provided by temperature data collected from an existing down-gradient borehole indicate that the geothermal system can most likely be classified as low-enthalpy and liquid dominated. We find the heat source for the system is likely cooling quartz monzonite intrusions in the shallow subsurface and that meteoric recharge in the pull-apart basin circulates to depth, rises along basin-bounding faults and discharges at the hot springs. While other combinations of subsurface properties and geothermal system configurations may fit the temperature distribution equally well, we demonstrate that the low-enthalpy system is reasonably explained based largely on interpretation of surface geophysical data and relatively simple models.

Tracking painted pebbles: Short-term rates of sediment movement on four Mojave Desert piedmont surfaces

NASA Astrophysics Data System (ADS)

Persico, Lyman P.; Nichols, Kyle K.; Bierman, Paul R.

2005-07-01

To quantify short-term sediment movement rates across Mojave Desert piedmonts, 1600 painted and numbered pebbles were laid out in paired, orthogonal, 20 m lines at 4 sites and resurveyed five times over 2 years and revisited 2 years later. Pebble lines cross shallow (5-15 cm), ephemeral channels and adjacent unconsolidated interfluves, the latter being the dominant landform at all sites. Two sites are located on surfaces that have been or are impacted by military training activities, including the use of tracked vehicles. The two other sites have not been disturbed by human impact. Three different processes transport pebbles. Episodic streamflow in ephemeral channels transports a few pebbles long distances (decimeters to meters) down gradient. Bioturbation moves many pebbles small distances (centimeters) in any direction, and vehicular disturbance transports pebbles varying distances (centimeters to meters) in any direction. Significant down-gradient sediment movement occurred dominantly in channels where flowing water was concentrated. Interfluves were stable surfaces where little transport occurred. Off-road vehicle use is coincident with accelerated pebble movement. Pebbles moved further and faster down gradient at the disturbed Iron Mountain and East Range Road sites (mean speeds of 0.18 and 0.34 m yr-1, respectively) than at the undisturbed Chemehuevi and Goldstone sites, (mean speeds of 0.17 and 0.02 m yr-1, respectively). Mean pebble movement is highly and negatively correlated with vegetation density. Short-term pebble movement rates are several times lower than long-term (103 to 104 year) rates, suggesting the importance of rare, extreme precipitation events for sediment transport such as those of fall and winter 2004.

Radiocarbon dating of dissolved inorganic carbon in groundwater from confined parts of the Upper Floridan aquifer, Florida, USA

USGS Publications Warehouse

Plummer, Niel; Sprinkle, C.L.

2001-01-01

Geochemical reaction models were evaluated to improve radiocarbon dating of dissolved inorganic carbon (DIC) in groundwater from confined parts of the Upper Floridan aquifer in central and northeastern Florida, USA. The predominant geochemical reactions affecting the 14C activity of DIC include (1) dissolution of dolomite and anhydrite with calcite precipitation (dedolomitization), (2) sulfate reduction accompanying microbial degradation of organic carbon, (3) recrystallization of calcite (isotopic exchange), and (4) mixing of fresh water with as much as 7% saline water in some coastal areas. The calculated cumulative net mineral transfers are negligibly small in upgradient parts of the aquifer and increase significantly in downgradient parts of the aquifer, reflecting, at least in part, upward leakage from the Lower Floridan aquifer and circulation that contacted middle confining units in the Floridan aquifer system. The adjusted radiocarbon ages are independent of flow path and represent travel times of water from the recharge area to the sample point in the aquifer. Downgradient from Polk City (adjusted age 1.7 ka) and Keystone Heights (adjusted age 0.4 ka), 14 of the 22 waters have adjusted 14C ages of 20-30 ka, indicating that most of the fresh-water resource in the Upper Floridan aquifer today was recharged during the last glacial period. All of the paleowaters are enriched in 18O and 2H relative to modern infiltration, with maximum enrichment in ??18O of approximately 2.0%o.

2016 Annual Reuse Report for the Idaho National Laboratory Site’s Advanced Test Reactor Complex Cold Waste Ponds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lewis, Michael George

This report describes conditions and information, as required by the state of Idaho, Department of Environmental Quality Reuse Permit I-161-02, for the Advanced Test Reactor Complex Cold Waste Ponds located at Idaho National Laboratory from November 1, 2015–October 31, 2016. The effective date of Reuse Permit I-161-02 is November 20, 2014 with an expiration date of November 19, 2019. This report contains the following information: • Facility and system description • Permit required effluent monitoring data and loading rates • Permit required groundwater monitoring data • Status of compliance activities • Issues • Discussion of the facility’s environmental impacts. Duringmore » the 2016 permit year, 180.99 million gallons of wastewater were discharged to the Cold Waste Ponds. This is well below the maximum annual permit limit of 375 million gallons. As shown by the groundwater sampling data, sulfate and total dissolved solids concentrations are highest in well USGS-065, which is the closest downgradient well to the Cold Waste Ponds. Sulfate and total dissolved solids concentrations decrease rapidly as the distance downgradient from the Cold Waste Ponds increases. Although concentrations of sulfate and total dissolved solids are significantly higher in well USGS-065 than in the other monitoring wells, both parameters remained below the Ground Water Quality Rule Secondary Constituent Standards in well USGS-065. The facility was in compliance with the Reuse Permit during the 2016 permit year.« less

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

USGS Publications Warehouse

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

2006-01-01

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

Toxicity of organic chemical pollution in groundwater downgradient of a landfill (Grindsted, Denmark)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baun, A.; Jensen, S.D.; Bjerg, P.L.

2000-05-01

The aim of the present study was to describe the occurrence and distribution of toxicity related to organic chemical contaminants in the leachate plume downgradient of the Grindsted Landfill (Denmark). A total of 27 groundwater samples were preconcentrated by solid-phase extraction (SPE) using XAD-2 as the resin material. This treatment effectively eliminated sample matrix toxicity caused by inorganic salts and natural organic compounds and produced an aqueous concentrate of the nonvolatile chemical contaminants. The SPE extracts were tested in a battery of standardized short-term aquatic toxicity tests with luminescent bacteria (Vibrio fischeri), algae (Selenastrum capricornutum), and crustaceans (Daphnia magna). Additionalmore » genotoxicity tests were made using the umuC test (Salmonella typhimurium). Biotests with algae and luminescent bacteria were the most sensitive tests. On the basis of results with these two bioassays, it was concluded that SPE extracts of groundwater collected close to the landfill were toxic. The toxicity decreased with the distance from the landfill. At distances greater than 80 m from the border of the landfill, the groundwater toxicity was not significantly different from the background toxicity. SPE extracts were not toxic to Daphnia, and no genotoxicity was observed in the umuC test. The overall findings indicate that a battery of biotests applied on preconcentrated groundwater samples can be a useful tool for toxicity characterization and hazard ranking of groundwater polluted with complex chemical mixtures, such as landfill leachates.« less

Managed aquifer recharge of treated wastewater: water quality changes resulting from infiltration through the vadose zone.

PubMed

Bekele, Elise; Toze, Simon; Patterson, Bradley; Higginson, Simon

2011-11-01

Secondary treated wastewater was infiltrated through a 9 m-thick calcareous vadose zone during a 39 month managed aquifer recharge (MAR) field trial to determine potential improvements in the recycled water quality. The water quality improvements of the recycled water were based on changes in the chemistry and microbiology of (i) the recycled water prior to infiltration relative to (ii) groundwater immediately down-gradient from the infiltration gallery. Changes in the average concentrations of several constituents in the recycled water were identified with reductions of 30% for phosphorous, 66% for fluoride, 62% for iron and 51% for total organic carbon when the secondary treated wastewater was infiltrated at an applied rate of 17.5 L per minute with a residence time of approximately four days in the vadose zone and less than two days in the aquifer. Reductions were also noted for oxazepam and temazepam among the pharmaceuticals tested and for a range of microbial pathogens, but reductions were harder to quantify as their magnitudes varied over time. Total nitrogen and carbamazepine persisted in groundwater down-gradient from the infiltration galleries. Infiltration does potentially offer a range of water quality improvements over direct injection to the water table without passage through the unsaturated zone; however, additional treatment options for the non-potable water may still need to be considered, depending on the receiving environment or the end use of the recovered water. Crown Copyright © 2011. Published by Elsevier Ltd. All rights reserved.

Partitioning microbial respiration between jet fuel and native organic matter in an organic-rich long time-contaminated aquifer.

PubMed

Bugna, G C; Chanton, J P; Stauffer, T B; MacIntyre, W G; Libelo, E L

2005-07-01

The relative importance of jet fuel biodegradation relative to the respiration of natural organic matter in a contaminated organic-rich aquifer underlying a fire training area at Tyndall Air Force Base, Florida, USA was determined with isotopic measurements. Thirteen wells were sampled and analyzed for BTX (benzene, toluene, xylene), dissolved inorganic carbon (DIC) and CH4 concentrations, and delta13C and 14C of DIC. Results range from non-detectable to 3790 ppb, 1.4-24 mM, 0.2-776 microM, +5.8 per thousand to -22 per thousand, and from 52 to 99 pmc, respectively. Residual fuel was confined to two center wells underlying the fire training area. DIC and CH4 concentrations were elevated down-gradient of the contamination, but also at sites that were not in the apparent flow path of the contaminated groundwater. DIC exhibited greatest delta13C enrichment at highest DIC and CH4 concentrations indicating that CH4 production was an important respiration mode. Radiocarbon-depleted DIC was observed at sites with high hydrocarbon concentrations and down-gradient of the site. The results indicate that while natural attenuation was not rapidly reducing the quantity of free product overlying the aquifer at the site of contamination, it was at least constraining its flow away from the spill site. Apparently under the conditions of this study, BTX was degraded as rapidly as it was dissolved.

Potential aquifer vulnerability in regions down-gradient from uranium in situ recovery (ISR) sites.

PubMed

Saunders, James A; Pivetz, Bruce E; Voorhies, Nathan; Wilkin, Richard T

2016-12-01

Sandstone-hosted roll-front uranium ore deposits originate when U(VI) dissolved in groundwater is reduced and precipitated as insoluble U(IV) minerals. Groundwater redox geochemistry, aqueous complexation, and solute migration are important in leaching uranium from source rocks and transporting it in low concentrations to a chemical redox interface where it is deposited in an ore zone typically containing the uranium minerals uraninite, pitchblende, and/or coffinite; various iron sulfides; native selenium; clays; and calcite. In situ recovery (ISR) of uranium ores is a process of contacting the uranium mineral deposit with leaching and oxidizing (lixiviant) fluids via injection of the lixiviant into wells drilled into the subsurface aquifer that hosts uranium ore, while other extraction wells pump the dissolved uranium after dissolution of the uranium minerals. Environmental concerns during and after ISR include water quality degradation from: 1) potential excursions of leaching solutions away from the injection zone into down-gradient, underlying, or overlying aquifers; 2) potential migration of uranium and its decay products (e.g., Ra, Rn, Pb); and, 3) potential mobilization and migration of redox-sensitive trace metals (e.g., Fe, Mn, Mo, Se, V), metalloids (e.g., As), and anions (e.g., sulfate). This review describes the geochemical processes that control roll-front uranium transport and fate in groundwater systems, identifies potential aquifer vulnerabilities to ISR operations, identifies data gaps in mitigating these vulnerabilities, and discusses the hydrogeological characterization involved in developing a monitoring program. Published by Elsevier Ltd.

Pharmaceuticals and other organic wastewater contaminants within a leachate plume downgradient of a municipal landfill

USGS Publications Warehouse

Barnes, Kimberlee K.; Christenson, Scott C.; Kolpin, Dana W.; Focazio, Michael J.; Furlong, Edward T.; Zaugg, Steven D.; Meyer, Michael T.; Barber, Larry B.

2004-01-01

Ground water samples collected from the Norman Landfill research site in central Oklahoma were analyzed as part of the U.S. Geological Survey (USGS) Toxic Substances Hydrology Program's national reconnaissance of pharmaceuticals and other organic waste water contaminants (OWCs) in ground water. Five sites, four of which are located downgradient of the landfill, were sampled in 2000 and analyzed for 76 OWCs using four research methods developed by the USGS. OWCs were detected in water samples from all of the sites sampled, with 22 of the 76 OWCs being detected at least once. Cholesterol (a plant and animal steroid), was detected at all five sites and was the only compound detected in a well upgradient of the landfill. N,Ndiethyltoluamide (DEET used in insect repellent) and tri(2-chloroethyl) phosphate (fire-retardant) were detected in water samples from all four sites located within the landfill-derived leachate plume. The sites closest to the landfill had more detections and greater concentrations of each of the detected compounds than sites located farther away. Detection of multiple OWCs occurred in the four sites located within the leachate plume, with a minimum of four and a maximum of 17 OWCs detected. Because the landfill was established in the 1920s and closed in 1985, many compounds detected in the leachate plume were likely disposed of decades ago. These results indicate the potential for long-term persistence and transport of some OWCs in ground water.

The combined use of 87Sr/86Sr and carbon and water isotopes to study the hydrochemical interaction between groundwater and lakewater in mantled karst

USGS Publications Warehouse

Katz, B.G.; Bullen, T.D.

1996-01-01

The hydrochemical interaction between groundwater and lakewater influences the composition of water that percolates downward from the surficial aquifer system through the underlying intermediate confining unit and recharges the Upper Floridan aquifer along highlands in Florida. The 87Sr/86Sr ratio along with the stable isotopes, D, 18O, and 13C were used as tracers to study the interaction between groundwater, lakewater, and aquifer minerals near Lake Barco, a seepage lake in the mantled karst terrane of northern Florida. Upgradient from the lake, the 87Sr/86Sr ratio of groundwater decreases with depth (mean values of 0.71004, 0.70890, and 0.70852 for water from the surficial aquifer system, intermediate confining unit, and Upper Floridan aquifer, respectively), resulting from the interaction of dilute oxygenated recharge water with aquifer minerals that are less radiogenic with depth. The concentrations of Sr2+ generally increase with depth, and higher concentrations of Sr2+ in water from the Upper Floridan aquifer (20-35 ??g/L), relative to water from the surficial aquifer system and the intermediate confining unit, result from the dissolution of Sr-bearing calcite and dolomite in the Eocene limestone. Dissolution of calcite [??13C = -1.6 permil (???)] is also indicated by an enriched ??13CDIC (-8.8 to - 11.4???) in water from the Upper Floridan aquifer, relative to the overlying hydrogeologic units (??13CDIC < - 16???). Groundwater downgradient from Lake Barco was enriched in 18O and D relative to groundwater upgradient from the lake, indicating mixing of lakewater leakage and groundwater. Downgradient from the lake, the 87Sr/86Sr ratio of groundwater and aquifer material become less radiogenic and the Sr2+ concentrations generally increase with depth. However, Sr2+ concentrations are substantially less than in upgradient groundwaters at similar depths. The lower Sr2+ concentrations result from the influence of anoxic lakewater leakage on the mobility of Sr2+ from clays. Based on results from mass-balance modeling, it is probable that cation exchange plays the dominant role in controlling the 87Sr/86Sr ratio of groundwater, both upgradient and downgradient from Lake Barco. Even though groundwater from the three distinct hydrogeologic units displays considerable variability in Sr concentration and isotopic composition, the dominant processes associated with the mixing of lakewater leakage with groundwater, as well as the effects of mineral-water interaction, can be ascertained by integrating the use of stable and radiogenic isotopic measurements of groundwater, lakewater, and aquifer minerals.

234U/238U evidence for local recharge and patterns of groundwater flow in the vicinity of Yucca Mountain, Nevada, USA

USGS Publications Warehouse

Paces, J.B.; Ludwig, K. R.; Peterman, Z.E.; Neymark, L.A.

2002-01-01

Uranium concentrations and 234U/238U ratios in saturated-zone and perched ground water were used to investigate hydrologic flow and downgradient dilution and dispersion in the vicinity of Yucca Mountain, a potential high-level radioactive waste disposal site. The U data were obtained by thermal ionization mass spectrometry on more than 280 samples from the Death Valley regional flow system. Large variations in both U concentrations (commonly 0.6-10 ??g 1-1) and 234U/238U activity ratios (commonly 1.5-6) are present on both local and regional scales; however, ground water with 234U/238U activity ratios from 7 up to 8.06 is restricted largely to samples from Yucca Mountain. Data from ground water in the Tertiary volcanic and Quaternary alluvial aquifers at and adjacent to Yucca Mountain plot in 3 distinct fields of reciprocal U concentration versus 234U/238U activity ratio correlated to different geographic areas. Ground water to the west of Yucca Mountain has large U concentrations and moderate 234U/238U whereas ground water to the east in the Fortymile flow system has similar 234U/238U, but distinctly smaller U concentrations. Ground water beneath the central part of Yucca Mountain has intermediate U concentrations but distinctive 234U/238U activity ratios of about 7-8. Perched water from the lower part of the unsaturated zone at Yucca Mountain has similarly large values of 234U/238U. These U data imply that the Tertiary volcanic aquifer beneath the central part of Yucca Mountain is isolated from north-south regional flow. The similarity of 234U/238U in both saturated- and unsaturated-zone ground water at Yucca Mountain further indicates that saturated-zone ground water beneath Yucca Mountain is dominated by local recharge rather than regional flow. The distinctive 234U/238U signatures also provide a natural tracer of downgradient flow. Elevated 234U/238U in ground water from two water-supply wells east of Yucca Mountain are interpreted as the result of induced flow from 40 a of ground-water withdrawal. Elevated 234U/238U in a borehole south of Yucca Mountain is interpreted as evidence that natural downgradient flow is more likely to follow southerly paths in the structurally anisotropic Tertiary volcanic aquifer where it becomes diluted by regional flow in the Fortymile system.

Borehole Data Package for 1998 Wells Installed at Single-Shell Tank Waste Management Area TX-TY

DOE Office of Scientific and Technical Information (OSTI.GOV)

DG Horton; FN Hodges

1999-03-23

Four new Resource Conservation and Recovery Act (RCRA) groundwater monitoring wells were installed at the single-shell tank farm Waste Management Area (WMA) TX-TY during August through November of 1998 in fi,dfillment of Tri-Party Agreement (Eoology 1996) milestone M-24-38. The wells are 299-W1O-26, 299-W14-13, 299-W14-14, and 299-W15-40. Well 299-W1O-26 is located outside the east fence of the TY tank farm and replaces downgradient well299-W1O-18; well 299-W14-13 is located along the east fence near the northeast corner of the TX tank f- and replaces downgradient well 299-W14-12; well 299-W14-14 is located outside the east fence in the south ha.lfof the TX tankmore » fiirm and is anew downgradient well; and well 299-W15-40 is located on the west side of the TX tank farm and is anew upgradient well. The locations of all wells in the monitoring network are shown on Figure 1. The groundwater monitoring plan for WMA TX-TY (Caggiano and Goodwin 1991) describes the hydrogeology of the 200 West Area and WMA TX-TY. An Interim Change Notice to the groundwater monitoring plan provides justification for the new wells. The new wells were constructed to the speciii- cations and requirements described in Washington Administrative Code (WAC) 173-160 and WAC 173-303. This document compiles &fiormation on the drilling and construction, well development pump instal- latio~ groundwater sampling, and sediment testing applicable to wells 299-W1O-26, 299-W14-13, 299-W14-14, and 299-W15-40. Appendix A contains the geologist's log, the Well Construction Sum- mary Repo~ and Well Summary Sheet (as-built diagram); Appendix B contains results of laboratory analyses of particle size distribution, p~ conductivity, calcium carbonate conten~ major cation and anion concentrations from 1:1 water: sediment extracts, and moisture conten~ Appendix C contains geophysical logs; and Appendix D contains the analytical results from groundwater samples obtained during well construction. Aqutier tests (slug tests) were performed on all the new wells after well completions. Results of the aquifer tests will be reported elsewhere. Additiond documentation concerning well construction is on fde with Bechtel Hanfor& Inc., Richland, Washington.« less

Thermal Protection System with Staggered Joints

NASA Technical Reports Server (NTRS)

Simon, Xavier D. (Inventor); Robinson, Michael J. (Inventor); Andrews, Thomas L. (Inventor)

2014-01-01

The thermal protection system disclosed herein is suitable for use with a spacecraft such as a reentry module or vehicle, where the spacecraft has a convex surface to be protected. An embodiment of the thermal protection system includes a plurality of heat resistant panels, each having an outer surface configured for exposure to atmosphere, an inner surface opposite the outer surface and configured for attachment to the convex surface of the spacecraft, and a joint edge defined between the outer surface and the inner surface. The joint edges of adjacent ones of the heat resistant panels are configured to mate with each other to form staggered joints that run between the peak of the convex surface and the base section of the convex surface.

Impact of Wildfire on Solute Release in Forested Catchments, Jemez River, New Mexico, USA

NASA Astrophysics Data System (ADS)

Sanchez, R. A.; Meixner, T.; McIntosh, J. C.; Chorover, J.

2017-12-01

Wildfires represent a large disturbance to the hydrology and biogeochemistry of forested catchments. The number, size and severity of wildfires have significantly increased in the western United States since 1990. Nutrients and other elements (e.g. Ca) that were taken up and stored by biomass are released from burned vegetation during forest fires and transported downgradient via overland flow, shallow subsurface flow, and/or deep groundwater flow. Ash accumulations on hillslopes may also store particulate carbon and contain elevated concentrations of elements that maybe leached into surface and ground water over extended periods of time. In 2013, the Thompson Ridge wildfire burned headwater catchments in the Jemez River Basin Critical Zone Observatory (JRB-CZO) within the Valles Caldera National Preserve, New Mexico USA. The burn severity and area impacted were different in the three headwater catchments. This study investigated the impact of the wildfire on surface water quality, including how the fire-induced impacts evolved with time, and how biogeochemical processes controlled post-fire solute concentrations in the surface water. Comparison of pre- and post-fire surface water solute chemistry shows increases in major cations and anions following fire. Increases in nitrate and sulfate concentrations in streams after the wildfire were likely from leaching of burned biomass. The elevated NO3- and SO42- concentrations persisted for over two years, and were even higher during spring snowmelt. Meanwhile, base cation concentrations increased immediately, within a few weeks after the fire, likely related to leaching from combusted organic matter; and, over a period of approximately two months, base cation concentrations returned to pre-fire levels. Trace element behavior was also altered by fire. For example, while pre-fire aluminum concentrations in stream flow increased significantly during the wet seasons (snowmelt and monsoons), the post-fire observations do not show significant changes with increase in discharge.

Using an implicitly-coupled hydrologic and river-operations models to investigate the trade-offs of artificial recharge in agricultural areas

NASA Astrophysics Data System (ADS)

Morway, E. D.; Niswonger, R. G.; Triana, E.

2016-12-01

In irrigated agricultural regions supplied by both surface-water and groundwater, increased reliance on groundwater during sustained drought leads to long-term water table drawdown and subsequent surface-water losses. This, in turn, may threaten the sustainability of the irrigation project. To help offset groundwater resource losses and restore water supply reliability, an alternative management strategy commonly referred to as managed aquifer recharge (MAR) in agricultural regions helps mitigate long-term aquifer drawdown and provides additional water for subsequent withdraw. Sources of MAR in this investigation are limited to late winter runoff in years with above average precipitation (i.e., above average snowpack). However, where winter MAR results in an elevated water table, non-beneficial consumptive use may increase from evapotranspiration in adjacent and down-gradient fallow and naturally vegetated lands. To rigorously explore this trade-off, the recently published MODSIM-MODFLOW model was applied to quantify both the benefits and unintended consequences of MAR. MODSIM-MODFLOW is a generalized modeling tool capable of exploring the effects of altered river operations within an integrated groundwater and surface-water (GW-SW) model. Thus, the MODSIM-MODFLOW model provides a modeling platform capable of simulating MAR in amounts and duration consistent with other senior water rights in the river system (e.g., minimum in-stream flow requirements). Increases in non-beneficial consumptive use resulting from winter MAR are evaluated for a hypothetical model patterned after alluvial aquifers common in arid and semi-arid areas of the western United States. Study results highlight (1) the benefit of an implicitly-coupled river operations and hydrologic modeling tool, (2) the balance between winter MAR and the potential increase in non-beneficial consumptive use, and (3) conditions where MAR may or may not be an appropriate management option, such as the availability of surface-water storage.

Coring the deep critical zone in the Jemez River Basin Critical Zone Observatory, Valles Caldera National Preserve, Northern New Mexico

NASA Astrophysics Data System (ADS)

Moravec, B. G.; White, A. M.; Paras, B.; Sanchez, A.; McGuffy, C.; Fairbanks, D.; McIntosh, J. C.; Pelletier, J. D.; Gallery, R. E.; Rasmussen, C.; Carr, B.; Holbrook, W. S.; Chorover, J.

2016-12-01

The Critical Zone (CZ) is the focus of current interdisciplinary Earth surface science research that aims to describe the interactions between geological and biological processes that influence ecosystem function, soil formation, nutrient and carbon cycling, hydrologic partitioning, biological activity and diversity, and mineral weathering. Prior research at the Catalina-Jemez (C-J) CZO has focused on the CZ near-surface, including remote sensing, and sampling/analysis of vegetation and soil microbiota, soils and saprolite, and surface water. However, the extent to which weathering, water/rock interaction, and solute mobility along flowpaths in the deep CZ respond to near surface CZ processes (i.e. water, energy, and mass fluxes) is not well understood. The goal of the present research is to understand depth-dependent trends in weathering dynamics from the mobile soil to unweathered bedrock in relation to landscape position (hillslope aspect and downgradient hollow). We used diamond core drilling techniques to excavate three boreholes to depths of 18.9, 41.8, and 46.3 meters in an instrumented forested sub-catchment of the C-J CZO in northern New Mexico. Here we present field methodology and preliminary data collected during the field campaign conducted during summer 2016. Element concentrations were measured during core extractions using portable X-ray fluorescence (XRF), which was subsequently validated against bench-scale XRF. Depth-dependent trends in both regolith depth and chemical depletion patterns show significant variation with landscape position. All three boreholes show complex weathering profiles with differences potentially due to textural controls on weathering, development of preferential flowpaths, and differing hydrologic base levels. Preliminary data indicate that chemical depletion patterns are not monotonic, but rather comprise large excursions that are being investigated for their relation to variation in local mineralogical composition and incongruent weathering reactions.

Determination of the origin of elevated uranium at a Former Air Force Landfill using non-parametric statistics analysis and uranium isotope ratio analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weismann, J.; Young, C.; Masciulli, S.

2007-07-01

Lowry Air Force Base (Lowry) was closed in September 1994 as part of the Base Realignment and Closure (BRAC) program and the base was transferred to the Lowry Redevelopment Authority in 1995. As part of the due diligence activities conducted by the Air Force, a series of remedial investigations were conducted across the base. A closed waste landfill, designated Operable Unit 2 (OU 2), was initially assessed in a 1990 Remedial Investigation (RI; [1]). A Supplemental Remedial Investigation was conducted in 1995 [2] and additional studies were conducted in a 1998 Focused Feasibility Study. [3] The three studies indicated thatmore » gross alpha, gross beta, and uranium concentrations were consistently above regulatory standards and that there were detections of low concentrations other radionuclides. Results from previous investigations at OU 2 have shown elevated gross alpha, gross beta, and uranium concentrations in groundwater, surface water, and sediments. The US Air Force has sought to understand the provenance of these radionuclides in order to determine if they could be due to leachates from buried radioactive materials within the landfill or whether they are naturally-occurring. The Air Force and regulators agreed to use a one-year monitoring and sampling program to seek to explain the origins of the radionuclides. Over the course of the one-year program, dissolved uranium levels greater than the 30 {mu}g/L Maximum Contaminant Level (MCL) were consistently found in both up-gradient and down-gradient wells at OU 2. Elevated Gross Alpha and Gross Beta measurements that were observed during prior investigations and confirmed during the LTM were found to correlate with high dissolved uranium content in groundwater. If Gross Alpha values are corrected to exclude uranium and radon contributions in accordance with US EPA guidance, then the 15 pCi/L gross alpha level is not exceeded. The large dataset also allowed development of gross alpha to total uranium correlation factors so that gross alpha action levels can be applied to future long-term landfill monitoring to track radiological conditions at lower cost. Ratios of isotopic uranium results were calculated to test whether the elevated uranium displayed signatures indicative of military use. Results of all ratio testing strongly supports the conclusion that the uranium found in groundwater, surface water, and sediment at OU 2 is naturally-occurring and has not undergone anthropogenic enrichment or processing. U-234:U-238 ratios also show that a disequilibrium state, i.e., ratio greater than 1, exists throughout OU 2 which is indicative of long-term aqueous transport in aged aquifers. These results all support the conclusion that the elevated uranium observed at OU 2 is due to the high concentrations in the regional watershed. Based on the results of this monitoring program, we concluded that the elevated uranium concentrations measured in OU 2 groundwater, surface water, and sediment are due to the naturally-occurring uranium content of the regional watershed and are not the result of waste burials in the former landfill. Several lines of evidence indicate that natural uranium has been naturally concentrated beneath OU 2 in the geologic past and the higher of uranium concentrations in down-gradient wells is the result of geochemical processes and not the result of a uranium ore disposal. These results therefore provide the data necessary to support radiological closure of OU 2. (authors)« less

Protection of surface states in topological nanoparticles

NASA Astrophysics Data System (ADS)

Siroki, Gleb; Haynes, Peter D.; Lee, Derek K. K.; Giannini, Vincenzo

2017-07-01

Topological insulators host protected electronic states at their surface. These states show little sensitivity to disorder. For miniaturization one wants to exploit their robustness at the smallest sizes possible. This is also beneficial for optical applications and catalysis, which favor large surface-to-volume ratios. However, it is not known whether discrete states in particles share the protection of their continuous counterparts in large crystals. Here we study the protection of the states hosted by topological insulator nanoparticles. Using both analytical and tight-binding simulations, we show that the states benefit from the same level of protection as those on a planar surface. The results hold for many shapes and sustain surface roughness which may be useful in photonics, spectroscopy, and chemistry. They complement past studies of large crystals—at the other end of possible length scales. The protection of the nanoparticles suggests that samples of all intermediate sizes also possess protected states.

Contamination movement around a permeable reactive barrier at Solid Waste Management Unit 12, Naval Weapons Station Charleston, North Charleston, South Carolina, 2009

USGS Publications Warehouse

Vroblesky, Don A.; Petkewich, Matthew D.; Conlon, Kevin J.

2010-01-01

The ability to monitor the fate and behavior of the plume in the forest is severely limited because the present axis of maximum contamination in that area bypasses all but one of the existing monitoring wells (12MW-12S). Moreover, the 2009 data indicate that there are no optimally placed sentinel wells in the probable path of contaminant transport. Thus the monitoring network is no longer adequate to monitor the groundwater contamination downgradient from the PRB.

The Impact of DNAPL Source-Zone Architecture on Contaminant Mass Flux and Plume Evolution in Heterogeneous Porous Media

DTIC Science & Technology

2013-08-01

remediation, ISCO, permanganate , persistence, DNAPL 16. SECURITY CLASSIFICATION OF: U 17. LIMITATION OF ABSTRACT 18. NUMBER OF PAGES 19a. NAME OF...focus on the lower-K zone 2 and surrounding higher-K matrix sand during the constant permanganate injection………………………… 45 Figure 5.1.3-3...Photographic image of the lower-K zone 2 and surrounding area after permanganate injection, exhibiting the shadow zone downgradient of the lower-K zone

Geohydrology, simulation of ground-water flow, and ground-water quality at two landfills, Marion County, Indiana

USGS Publications Warehouse

Duwelius, R.F.; Greeman, T.K.

1989-01-01

Concentrations of dissolved inorganic substances in ground-water samples indicate that leachate from both landfills is reaching the shallow aquifers. The effect on deeper aquifers is small because of the predominance of horizontal ground-water flow and discharge to the streams. Increases in almost all dissolved constituents were observed in shallow wells that are screened beneath and downgradient from the landfills. Several analyses, especially those for bromide, dissolved solids, and ammonia, were useful in delineating the plume of leachate at both landfills.

40 CFR 258.27 - Surface water requirements.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 25 2011-07-01 2011-07-01 false Surface water requirements. 258.27 Section 258.27 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES CRITERIA FOR MUNICIPAL SOLID WASTE LANDFILLS Operating Criteria § 258.27 Surface water requirements. MSWLF...

Use and environmental occurrence of pharmaceuticals in freestall dairy farms with manured forage fields

USGS Publications Warehouse

Watanabe, Naoko; Bergamaschi, Brian A.; Loftin, Keith A.; Meyer, Michael T.; Harter, Thomas

2010-01-01

Environmental releases of antibiotics from concentrated animal feeding operations (CAFOs) are of increasing regulatory concern. This study investigates the use and occurrence of antibiotics in dairy CAFOs and their potential transport into first-encountered groundwater. On two dairies we conducted four seasonal sampling campaigns, each across 13 animal production and waste management systems and associated environmental pathways: application to animals, excretion to surfaces, manure collection systems, soils, and shallow groundwater. Concentrations of antibiotics were determined using on line solid phase extraction (OLSPE) and liquid chromatography-tandem mass spectrometry (LC/MS/MS) with electrospray ionization (ESI) for water samples, and accelerated solvent extraction (ASE) LC/MS/MS with ESI for solid samples. A variety of antibiotics were applied at both farms leading to antibiotics excretion of several hundred grams per farm per day. Sulfonamides, tetracyclines, and their epimers/isomers, and lincomycin were most frequently detected. Yet, despite decades of use, antibiotic occurrence appeared constrained to within farm boundaries. The most frequent antibiotic detections were associated with lagoons, hospital pens, and calf hutches. When detected below ground, tetracyclines were mainly found in soils, whereas sulfonamides were found in shallow groundwater reflecting key differences in their physicochemical properties. In manure lagoons, 10 compounds were detected including tetracyclines and trimethoprim. Of these 10, sulfadimethoxine, sulfamethazine, and lincomycin were found in shallow groundwater directly downgradient from the lagoons. Antibiotics were sporadically detected in field surface samples on fields with manure applications, but not in underlying sandy soils. Sulfadimethoxine and sulfamethazine were detected in shallow groundwater near field flood irrigation gates, but at highly attenuated levels.

Use and environmental occurrence of antibiotics in freestall dairy farms with manured forage fields.

PubMed

Watanabe, Naoko; Bergamaschi, Brian A; Loftin, Keith A; Meyer, Michael T; Harter, Thomas

2010-09-01

Environmental releases of antibiotics from concentrated animal feeding operations (CAFOs) are of increasing regulatory concern. This study investigates the use and occurrence of antibiotics in dairy CAFOs and their potential transport into first-encountered groundwater. On two dairies we conducted four seasonal sampling campaigns, each across 13 animal production and waste management systems and associated environmental pathways: application to animals, excretion to surfaces, manure collection systems, soils, and shallow groundwater. Concentrations of antibiotics were determined using on line solid phase extraction (OLSPE) and liquid chromatography-tandem mass spectrometry (LC/MS/MS) with electrospray ionization (ESI) for water samples, and accelerated solvent extraction (ASE) LC/MS/MS with ESI for solid samples. A variety of antibiotics were applied at both farms leading to antibiotics excretion of several hundred grams per farm per day. Sulfonamides, tetracyclines, and their epimers/isomers, and lincomycin were most frequently detected. Yet, despite decades of use, antibiotic occurrence appeared constrained to within farm boundaries. The most frequent antibiotic detections were associated with lagoons, hospital pens, and calf hutches. When detected below ground, tetracyclines were mainly found in soils, whereas sulfonamides were found in shallow groundwater reflecting key differences in their physicochemical properties. In manure lagoons, 10 compounds were detected including tetracyclines and trimethoprim. Of these 10, sulfadimethoxine, sulfamethazine, and lincomycin were found in shallow groundwater directly downgradient from the lagoons. Antibiotics were sporadically detected in field surface samples on fields with manure applications, but not in underlying sandy soils. Sulfadimethoxine and sulfamethazine were detected in shallow groundwater near field flood irrigation gates, but at highly attenuated levels.

Use and Environmental Occurrence of Antibiotics in Freestall Dairy Farms with Manured Forage Fields

PubMed Central

2010-01-01

Environmental releases of antibiotics from concentrated animal feeding operations (CAFOs) are of increasing regulatory concern. This study investigates the use and occurrence of antibiotics in dairy CAFOs and their potential transport into first-encountered groundwater. On two dairies we conducted four seasonal sampling campaigns, each across 13 animal production and waste management systems and associated environmental pathways: application to animals, excretion to surfaces, manure collection systems, soils, and shallow groundwater. Concentrations of antibiotics were determined using on line solid phase extraction (OLSPE) and liquid chromatography-tandem mass spectrometry (LC/MS/MS) with electrospray ionization (ESI) for water samples, and accelerated solvent extraction (ASE) LC/MS/MS with ESI for solid samples. A variety of antibiotics were applied at both farms leading to antibiotics excretion of several hundred grams per farm per day. Sulfonamides, tetracyclines, and their epimers/isomers, and lincomycin were most frequently detected. Yet, despite decades of use, antibiotic occurrence appeared constrained to within farm boundaries. The most frequent antibiotic detections were associated with lagoons, hospital pens, and calf hutches. When detected below ground, tetracyclines were mainly found in soils, whereas sulfonamides were found in shallow groundwater reflecting key differences in their physicochemical properties. In manure lagoons, 10 compounds were detected including tetracyclines and trimethoprim. Of these 10, sulfadimethoxine, sulfamethazine, and lincomycin were found in shallow groundwater directly downgradient from the lagoons. Antibiotics were sporadically detected in field surface samples on fields with manure applications, but not in underlying sandy soils. Sulfadimethoxine and sulfamethazine were detected in shallow groundwater near field flood irrigation gates, but at highly attenuated levels. PMID:20698525

Tracing organic carbon processes in a shallow coastal sandy aquifer

NASA Astrophysics Data System (ADS)

Meredith, K.; Andersen, M. S.; Baker, A.; O'Carrol, D. M.; Bryan, E.; Zainuddin, N. S.; Rutlidge, H.; McDonough, L.

2017-12-01

Coastal groundwater resources are likely to be impacted by climate change due to changes in recharge patterns, surface water flow and sea-level rise, which all have the potential to change how carbon is transported and stored within a catchment. Large quantities of carbon are currently stored within coastal wetland systems, so understanding carbon dynamics is important for climate change predictions into the future. Furthermore, dissolved organic carbon (DOC) can play a major role in weathering processes and deterioration of water quality, therefore understanding the sources, degradation pathways and its reactivity is important. Groundwater samples were collected from five nested sites (15 wells) from a shallow (0-20m) coastal sandy aquifer system located at Anna Bay, New South Wales, Australia. Surface water samples were also collected from the adjacent wetland. Waters were measured for major ion chemistry, carbon isotopes (δ13CDIC, δ13CDOC and 14CDIC) and tritium (3H). The dissolved organic matter (DOM) character was determined using optical spectroscopy and liquid chromatography. DOC was found to be elevated in the wetland (18 ppm) and had the lowest δ13CDOC value (-30.3 ‰). The shallow (3.5 m) groundwater located closest to but downgradient of the wetland (5 m) had similar characteristics to the wetland sample but contained significantly lower DOC concentrations (5 ppm) and were 1 ‰ more enriched in δ13CDOC values. This suggests that the aquifer is a sink for organic matter and the process fractionates the carbon isotopes. Higher resolution studies are underway to characterise and constrain timescales for the DOC transformation processes.

Guidelines for design, installation, and maintenance of a waterproof wearing surface for timber bridge decks

Treesearch

Richard E. Weyers; Joseph R. Loferski; J. Daniel Dolan; John E. Haramis; Joseph H. Howard; Lola Hislop

2001-01-01

To enhance long-term timber bridge performance, timber material must be protected from moisture. Wearing surfaces made of asphalt pavement with and without a waterproof membrane have been used to provide protection from moisture on timber decks. This type of wearing surface also protects the deck from other damage while providing a smooth, skid-resistant surface....

Hydrogeologic Characteristics of the St. Croix River Basin, Minnesota and Wisconsin: Implications for the Susceptibility of Ground Water to Potential Contamination

USGS Publications Warehouse

Juckem, Paul F.

2007-01-01

Population growth in the St. Croix River Basin in Minnesota and Wisconsin has intensified concerns of county resource managers and the National Park Service, which is charged with protecting the St. Croix National Scenic Riverway, about the potential for ground-water contamination in the basin. This report describes a previously developed method that was adapted to illustrate potential ground-water-contamination susceptibility in the St. Croix River Basin. The report also gives an estimate of ground-water-residence time and surface-water/ground-water interaction as related to natural attenuation and movement of contaminants in five tributary basins. A ground-water-contamination-susceptibility map was adapted from a state-wide map of Wisconsin to the St. Croix River Basin by use of well-driller construction records and regional maps of aquifer properties in Minnesota and Wisconsin. Measures of various subsurface properties were combined to generate a spatial index of susceptibility. The subjective index method developed for the State of Wisconsin by Schmidt (1987) was not derived from analyses of water-quality data or physical processes. Nonetheless, it was adapted for this report to furnish a seamless map across state boundaries that would be familiar to many resource managers. Following this method, areas most susceptible to contamination appear to have coarse-grained sediments (sands or gravels) and shallow water tables or are underlain by carbonate-bedrock aquifers. The least susceptible areas appear to have fine-grained sediments and deep water tables. If an aquifer becomes contaminated, the ground-water-residence time can affect potential natural attenuation along the ground-water-flow path. Mean basin ground-water-residence times were computed for the Apple, Kettle, Kinnickinnic, Snake and Sunrise River Basins, which are tributary basins to the St. Croix Basin, by use of average aquifer properties of saturated thickness, porosity, and recharge rates. The Apple River Basin had the shortest mean ground-water-residence times (20-120 years), owing largely to the moderate saturated thickness and high recharge rate in the basin. The Kinnickinnic and Sunrise River Basins had the longest mean residence times (60-350 and 70-390 years, respectively) chiefly because of the relatively large saturated thickness of the basins. Owing to limitations of the residence-time calculations, actual ground-water-residence times will vary around the mean values within each basin and may range from days or weeks in karst carbonate aquifers to millennia in deep confined sandstone aquifers. Areas of relatively short residence time (less than the median residence time in each basin) were identified by use of ground-water-flow models for each of the five tributary basins. Results of simulations show that these areas, in which contaminants may have relatively less time for natural attenuation along the short flow paths, generally occur near streams and rivers where ground water discharges to the surface. Finally, the ground-water-flow models were used to simulate ground-water/surface-water interaction in the five tributary basins. Results of simulations show that some lakes and reservoirs leak surface water into the ground-water-flow system on their downgradient side, where the surface-water outflow has been restricted by a dam or a naturally constricted outlet. These locations are noteworthy because contaminated surface waters could potentially enter the ground-water-flow system at these locations.

Evaluation of a scalar eddy transport coefficient based on geometric constraints

NASA Astrophysics Data System (ADS)

Bachman, S. D.; Marshall, D. P.; Maddison, J. R.; Mak, J.

2017-01-01

A suite of idealized models is used to evaluate and compare several previously proposed scalings for the eddy transport coefficient in downgradient mesoscale eddy closures. Of special interest in this comparison is a scaling introduced as part of the eddy parameterization framework of Marshall et al. (2012), which is derived using the inherent geometry of the Eliassen-Palm eddy flux tensor. The primary advantage of using this coefficient in a downgradient closure is that all dimensional terms are explicitly specified and the only uncertainty is a nondimensional parameter, α, which is bounded by one in magnitude. In each model a set of passive tracers is initialized, whose flux statistics are used to invert for the eddy-induced tracer transport. Unlike previous work, where this technique has been employed to diagnose the tensor coefficient of a linear flux-gradient relationship, the idealization of these models allows the lateral eddy transport to be described by a scalar coefficient. The skill of the extant scalings is then measured by comparing their predicted values against the coefficients diagnosed using this method. The Marshall et al. (2012), scaling is shown to scale most closely with the diagnosed coefficients across all simulations. It is shown that the skill of this scaling is due to its functional dependence on the total eddy energy, and that this scaling provides an excellent match to the diagnosed fluxes even in the limit of constant α. Possible extensions to this work, including how to incorporate the resultant transport coefficient into the Gent and McWilliams parameterization, are discussed.

Geophysical monitoring of a field-scale biostimulation pilot project

USGS Publications Warehouse

Lane, J.W.; Day-Lewis, F. D.; Casey, C.C.

2006-01-01

The USGS conducted a geophysical investigation in support of a U.S. Naval Facilities Engineering Command, Southern Division field-scale biostimulation pilot project at Anoka County Riverfront Park (ACP), downgradient of the Naval Industrial Reserve Ordnance Plant, Fridley, Minnesota. The goal of the pilot project is to evaluate subsurface injection of vegetable oil emulsion (VOE) to stimulate microbial degradation of chlorinated hydrocarbons. To monitor the emplacement and movement of the VOE and changes in water chemistry resulting from VOE dissolution and/or enhanced biological activity, the USGS acquired cross-hole radar zero-offset profiles, traveltime tomograms, and borehole geophysical logs during five site visits over 1.5 years. Analysis of pre- and postinjection data sets using petrophysical models developed to estimate VOE saturation and changes in total dissolved solids provides insights into the spatial and temporal distribution of VOE and ground water with altered chemistry. Radar slowness-difference tomograms and zero-offset slowness profiles indicate that the VOE remained close to the injection wells, whereas radar attenuation profiles and electromagnetic induction logs indicate that bulk electrical conductivity increased downgradient of the injection zone, diagnostic of changing water chemistry. Geophysical logs indicate that some screened intervals were located above or below zones of elevated dissolved solids; hence, the geophysical data provide a broader context for interpretation of water samples and evaluation of the biostimulation effort. Our results include (1) demonstration of field and data analysis methods for geophysical monitoring of VOE biostimulation and (2) site-specific insights into the spatial and temporal distributions of VOE at the ACP. ?? 2006 National Ground Water Association.

Geohydrology and ground-water quality at the Pueblo Depot activity landfill near Pueblo, Colorado

USGS Publications Warehouse

Watts, Kenneth R.; Ortiz, Roderick F.

1990-01-01

Groundwater samples were collected from the shallow unconfined aquifer at the Pueblo Depot Activity (Colorado) landfill and downstream from the landfill. The Pueblo Depot Activity is a U.S. Department of the Army facility in southeastern Colorado about 15 miles east of Pueblo, Colorado. The land-fill is underlain by upland alluvial terrace deposits that overlie a thick and almost impermeable shale. Saturated thickness of the aquifer generally is from 5 to 10 feet. Groundwater flow at the landfill is to the south-southeast toward the Arkansas River valley. Though not hydraulically connected to the upland terrace deposits, the alluvium underlying the Arkansas River valley may be recharged by groundwater that is discharged from seeps at the contact of the upland terrace deposits and the Pierre Shale. The water is classified as a mixed-cation mixed-anion type water that has concentrations of dissolved solids of 710 to 1,810 mg/L. Dissolved-solids concentrations increase downgradient. Chemical analysis, done to determine possible contamination of the groundwater, indicated that concentrations of trichloroethylene ranged from 5.2 to 2,900 microg/L and of trans-1,2-dichloroethylene ranged from 5 to 720 microg/L. The areal distribution of these volatile organic compounds indicate that there possibly are two sources of contamination of groundwater at the landfill, one upgradient from the landfill and the other within the landfill. Analysis of water samples from wells and seeps offsite and downgradient from the landfill did not indicate either contaminant in groundwater from the alluvial aquifer underlying the Arkansas River valley. (USGS)

Effects of selected sources of contamination on ground-water quality at seven sites in Connecticut

USGS Publications Warehouse

Handman, Elinor H.; Bingham, James W.

1980-01-01

The introduction of contaminants has altered the quality of ground water at several places in Connecticut. This investigation of the hydrogeologic environment and the quality of water in stratified-drift aquifers underlying seven probable contaminant sources in Connecticut shows some effects at each site. Water from test wells downgradient from septage-disposal facilities in Old Saybrook and Clinton contains elevated concentrations of sodium, chloride, manganese, iron, detergent (as MBAS), dissolved organic carbon, and some trace metals. The effects are most pronounced at shallow depths close to the septage lagoons, where concentrations of some constituents exceed Connecticut Department of Health drinking water standards. Fly-ash disposal at Wallingford has contributed chromium, manganese, and dissolved organic carbon to water in the underlying aquifer, but the low hydraulic conductivity of the fine-grained surficial materials have kept effects to a minimum. Road salt leached from a storage area in the Tylerville section of Haddam has increased the sodium and chloride concentrations in ground water to the extent that it is unsuitable for drinking water. The effect diminishes in wells 1000 feet downgradient from the storage site. Water from some wells adjacent to landfills in Bristol and Southington has elevated sodium, chloride, manganese, and dissolved organic carbon concentrations, and samples from two wells near industrial-sludge disposal pits in the Bristol landfill contain cyanide and phenols. Gasoline odor is present in water samples from a test well 175 feet from a ruptured buried tank in Fairfield. The gasoline odor from this well was also detectable during well construction and sampling.

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

USGS Publications Warehouse

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

2001-01-01

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 .

Geophysical monitoring of a field-scale biostimulation pilot project.

PubMed

Lane, John W; Day-Lewis, Frederick D; Casey, Clifton C

2006-01-01

The USGS conducted a geophysical investigation in support of a U.S. Naval Facilities Engineering Command, Southern Division field-scale biostimulation pilot project at Anoka County Riverfront Park (ACP), down-gradient of the Naval Industrial Reserve Ordnance Plant, Fridley, Minnesota. The goal of the pilot project is to evaluate subsurface injection of vegetable oil emulsion (VOE) to stimulate microbial degradation of chlorinated hydrocarbons. To monitor the emplacement and movement of the VOE and changes in water chemistry resulting from VOE dissolution and/or enhanced biological activity, the USGS acquired cross-hole radar zero-offset profiles, travel-time tomograms, and borehole geophysical logs during five site visits over 1.5 years. Analysis of pre- and postinjection data sets using petrophysical models developed to estimate VOE saturation and changes in total dissolved solids provides insights into the spatial and temporal distribution of VOE and ground water with altered chemistry. Radar slowness-difference tomograms and zero-offset slowness profiles indicate that the VOE remained close to the injection wells, whereas radar attenuation profiles and electromagnetic induction logs indicate that bulk electrical conductivity increased down-gradient of the injection zone, diagnostic of changing water chemistry. Geophysical logs indicate that some screened intervals were located above or below zones of elevated dissolved solids; hence, the geophysical data provide a broader context for interpretation of water samples and evaluation of the biostimulation effort. Our results include (1) demonstration of field and data analysis methods for geophysical monitoring of VOE biostimulation and (2) site-specific insights into the spatial and temporal distributions of VOE at the ACP.

Displacement of soil pore water by trichloroethylene

USGS Publications Warehouse

Wershaw, R. L.; Aiken, G.R.; Imbrigiotta, T.E.; Goldberg, M.C.

1994-01-01

Dense nonaqueous phase liquids (DNAPLS) are important pollutants because of their widespread use as chemical and industrial solvents. An example of the pollution caused by the discharge of DNAPLs is found at the Picatinny Arsenal, New Jersey, where trichloroethylene (TCE) has been discharged directly into the unsaturated zone. This discharge has resulted in the formation of a plume of TCE-contaminated water in the aquifer downgradient of the discharge. A zone of dark-colored groundwater containing a high dissolved organic C content has been found near the point of discharge of the TCE. The colored-water plume extends from the point of discharge at least 30 m (100 feet) downgradient. Fulvic acids isolated from the colored-waters plume, from water from a background well that has not been affected by the discharge of chlorinated solvents, and from soil pore water collected in a lysimeter installed at an uncontaminated site upgradient of the study area have been compared. Nuclear magnetic resonance spectra of the fulvic acids from the colored waters and from the lysimeter are very similar, but are markedly different from the nuclear magnetic resonance spectrum of the fulvic acid from the background well. The three-dimensional fluorescence spectrum and the DOC fractionation profile of the colored groundwater and the soil pore water are very similar to each other, but quite different from those of the background water. It is proposed from these observations that this colored water is soil pore water that has been displaced by a separate DNAPL liquid phase downward to the saturated zone.

A new paradigm for predicting zonal-mean climate and climate change

NASA Astrophysics Data System (ADS)

Armour, K.; Roe, G.; Donohoe, A.; Siler, N.; Markle, B. R.; Liu, X.; Feldl, N.; Battisti, D. S.; Frierson, D. M.

2016-12-01

How will the pole-to-equator temperature gradient, or large-scale patterns of precipitation, change under global warming? Answering such questions typically involves numerical simulations with comprehensive general circulation models (GCMs) that represent the complexities of climate forcing, radiative feedbacks, and atmosphere and ocean dynamics. Yet, our understanding of these predictions hinges on our ability to explain them through the lens of simple models and physical theories. Here we present evidence that zonal-mean climate, and its changes, can be understood in terms of a moist energy balance model that represents atmospheric heat transport as a simple diffusion of latent and sensible heat (as a down-gradient transport of moist static energy, with a diffusivity coefficient that is nearly constant with latitude). We show that the theoretical underpinnings of this model derive from the principle of maximum entropy production; that its predictions are empirically supported by atmospheric reanalyses; and that it successfully predicts the behavior of a hierarchy of climate models - from a gray radiation aquaplanet moist GCM, to comprehensive GCMs participating in CMIP5. As an example of the power of this paradigm, we show that, given only patterns of local radiative feedbacks and climate forcing, the moist energy balance model accurately predicts the evolution of zonal-mean temperature and atmospheric heat transport as simulated by the CMIP5 ensemble. These results suggest that, despite all of its dynamical complexity, the atmosphere essentially responds to energy imbalances by simply diffusing latent and sensible heat down-gradient; this principle appears to explain zonal-mean climate and its changes under global warming.

Use of a ground-water flow model with particle tracking to evaluate ground-water vulnerability, Clark County, Washington

USGS Publications Warehouse

Snyder, D.T.; Wilkinson, J.M.; Orzol, L.L.

1996-01-01

A ground-water flow model was used in conjunction with particle tracking to evaluate ground-water vulnerability in Clark County, Washington. Using the particle-tracking program, particles were placed in every cell of the flow model (about 60,000 particles) and tracked backwards in time and space upgradient along flow paths to their recharge points. A new computer program was developed that interfaces the results from a particle-tracking program with a geographic information system (GIS). The GIS was used to display and analyze the particle-tracking results. Ground-water vulnerability was evaluated by selecting parts of the ground-water flow system and combining the results with ancillary information stored in the GIS to determine recharge areas, characteristics of recharge areas, downgradient impact of land use at recharge areas, and age of ground water. Maps of the recharge areas for each hydrogeologic unit illustrate the presence of local, intermediate, or regional ground-water flow systems and emphasize the three-dimensional nature of the ground-water flow system in Clark County. Maps of the recharge points for each hydrogeologic unit were overlaid with maps depicting aquifer sensitivity as determined by DRASTIC (a measure of the pollution potential of ground water, based on the intrinsic characteristics of the near-surface unsaturated and saturated zones) and recharge from on-site waste-disposal systems. A large number of recharge areas were identified, particularly in southern Clark County, that have a high aquifer sensitivity, coincide with areas of recharge from on-site waste-disposal systems, or both. Using the GIS, the characteristics of the recharge areas were related to the downgradient parts of the ground-water system that will eventually receive flow that has recharged through these areas. The aquifer sensitivity, as indicated by DRASTIC, of the recharge areas for downgradient parts of the flow system was mapped for each hydrogeologic unit. A number of public-supply wells in Clark County may be receiving a component of water that recharged in areas that are more conducive to contaminant entry. The aquifer sensitivity maps illustrate a critical deficiency in the DRASTIC methodology: the failure to account for the dynamics of the ground-water flow system. DRASTIC indices calculated for a particular location thus do not necessarily reflect the conditions of the ground-water resources at the recharge areas to that particular location. Each hydrogeologic unit was also mapped to highlight those areas that will eventually receive flow from recharge areas with on-site waste-disposal systems. Most public-supply wells in southern Clark County may eventually receive a component of water that was recharged from on-site waste-disposal systems.Traveltimes from particle tracking were used to estimate the minimum and maximum age of ground water within each model-grid cell. Chlorofluorocarbon (CFC)-age dating of ground water from 51 wells was used to calibrate effective porosity values used for the particle- tracking program by comparison of ground-water ages determined through the use of the CFC-age dating with those calculated by the particle- tracking program. There was a 76 percent agreement in predicting the presence of modern water in the 51 wells as determined using CFCs and calculated by the particle-tracking program. Maps showing the age of ground water were prepared for all the hydrogeologic units. Areas with the youngest ground-water ages are expected to be at greatest risk for contamination from anthropogenic sources. Comparison of these maps with maps of public- supply wells in Clark County indicates that most of these wells may withdraw ground water that is, in part, less than 100 years old, and in many instances less than 10 years old. Results of the analysis showed that a single particle-tracking analysis simulating advective transport can be used to evaluate ground-water vulnerability for any part of a ground-wate

Data Validation Package, July 2016 Groundwater Sampling at the Shirley Basin South, Wyoming, Disposal Site November 2016

DOE Office of Scientific and Technical Information (OSTI.GOV)

Frazier, William; Price, Jeffrey

Sampling Period: July 14-15, 2016 The 2004 Long-Term Surveillance Plan for the Shirley Basin South (UMTRCA Title II) Disposal Site, Carbon County, Wyoming, requires annual monitoring to verify continued compliance with the pertinent alternate concentration limits (ACLs) and Wyoming Class III (livestock use) groundwater protection standards. Planned monitoring locations are shown in Attachment 1, Sampling and Analysis Work Order. Point-of-compliance (POC) wells 19-DC, 5-DC, and 5-SC, and monitoring wells 10-DC, 110-DC, 112-DC, 113-DC, 40-SC, 54-SC, 100-SC, 102-SC, and K.G.S.#3 were sampled. POC well 51-SC and downgradient well 101-SC were dry at the time of sampling. The water level was measuredmore » at each sampled well. See Attachment 2, Trip Report for additional details. Sampling and analyses were conducted in accordance with the Sampling and Analysis Plan for the U S. Department of Energy Office of Legacy Management Sites (LMS/PRO/S04351, continually updated, http://energy.gov/lm/downloads/sampling-and­ analysis-plan-us-department-energy-office-legacy-management-sites). ACLs are approved for cadmium, chromium, lead, nickel, radium-226, radium-228, selenium, thorium-230, and uranium in site groundwater. Time-concentration graphs of the contaminants of concern in POC wells are included in Attachment 3, Data Presentation. The only ACL exceedance in a POC well was radium-228 in well 5-DC where the concentration was 30.7 picocuries per liter (pCi/L), exceeding the ACL of 25.7 pCi/L. Concentrations of sulfate and total dissolved solids continue to exceed their respective Wyoming Class III groundwater protection standards for livestock use in wells 5-DC, 5-SC, and 54-SC as they have done throughout the sampling history; however, there is no livestock use of the water from these aquifers at the site, and no constituent concentrations exceed groundwater protection standards at the wells near the site boundary.« less

Movement and fate of creosote waste in ground water, Pensacola, Florida; U.S. Geological Survey toxic waste-ground-water contamination program

USGS Publications Warehouse

Mattraw, Harold C.; Franks, Bernard J.

1986-01-01

Ground- and surface-water contamination by pesticides used in the wood-preserving industry is widespread in the United States. Pine poles were treated with wood preservatives from 1902 to 1981 at a creosote works near Pensacola, Florida. Diesel fuel, creosote, and pentachlorophenol were discharged to two unlined impoundments that had a direct hydraulic connection to the sand-and-gravel aquifer. Evidence of wood-preserving waste contamination appears to be confined to the upper 30 meters of the aquifer. The waste plume extends downgradient approximately 300 meters south toward Pensacola Bay. In 1983, the creosote works site was selected by the U.S. Geological Survey's Office of Hazardous Waste Hydrology as a national research demonstration area to apply the latest techniques for characterizing hazardous waste problems. The multidisciplinary research effort is aimed at studying processes that affect the occurrence, transport, transformations, and fate of the toxic contaminants associated with wood preservatives in the environment. Clusters of two to five wells were constructed at different depths at nine sites to define the depth of contamination. Research studies are investigating sorption, dispersion, dilution, chemical reactions, bacterially mediated transformations, quality assurance, plume hydrodynamics, and the ultimate fate of these complex organic wastes.

Effects of septic-tank effluent on ground-water quality in northern Williamson County and southern Davidson County, Tennessee

USGS Publications Warehouse

Hanchar, D.W.

1991-01-01

An investigation of the potential contamination of ground water from septic tank systems blasted in bedrock in Williamson and Davidson Counties, Tennessee, was conducted during 1988-89. Water samples were collected from domestic and observation wells, springs, and surface-water sites in a residential subdivision in the northern part of Williamson County near Nashville. The subdivision has a high density of septic-tank field lines installed into blasted bedrock Water samples also were collected from a well located in an area of Davidson County where field lines were installed in 5 feet of soil. Samples were analyzed for major inorganic constituents, nutrients, total organic carbon, optical brighteners, and bacteria. Although results of analyses of water samples from wells indicate no effect of septic-tank effluent on ground-water quality at these sites, water from two springs located downgradient from the subdivision had slightly larger concentrations of nitrite plus nitrate (2.2 and 2.7 milligrams per liter N), and much larger concentrations of fecal coliform and fecal streptococci bacteria (2,000 to 3,200 and 700 to 900 colonies per 100 milliliters of sample, respectively), than other wells and springs sampled during 1988. Water from one of these springs contained optical brighteners, which indicates that septic-tank effluent is affecting ground-water quality.

Concentration-Discharge Relations in the Critical Zone: Implications for Resolving Critical Zone Structure, Function, and Evolution

NASA Astrophysics Data System (ADS)

Chorover, Jon; Derry, Louis A.; McDowell, William H.

2017-11-01

Critical zone science seeks to develop mechanistic theories that describe critical zone structure, function, and long-term evolution. One postulate is that hydrogeochemical controls on critical zone evolution can be inferred from solute discharges measured down-gradient of reactive flow paths. These flow paths have variable lengths, interfacial compositions, and residence times, and their mixing is reflected in concentration-discharge (C-Q) relations. Motivation for this special section originates from a U.S. Critical Zone Observatories workshop that was held at the University of New Hampshire, 20-22 July 2015. The workshop focused on resolving mechanistic CZ controls over surface water chemical dynamics across the full range of lithogenic (e.g., nonhydrolyzing and hydrolyzing cations and oxyanions) and bioactive solutes (e.g., organic and inorganic forms of C, N, P, and S), including dissolved and colloidal species that may cooccur for a given element. Papers submitted to this special section on "concentration-discharge relations in the critical zone" include those from authors who attended the workshop, as well as others who responded to the open solicitation. Submissions were invited that utilized information pertaining to internal, integrated catchment function (relations between hydrology, biogeochemistry, and landscape structure) to help illuminate controls on observed C-Q relations.

Movement and fate of creosote waste in ground water, Pensacola, Florida; U.S. Geological Survey toxic waste--ground-water contamination program

USGS Publications Warehouse

Mattraw, H. C.; Franks, B.J.

1984-01-01

In 1983, the U.S. Geological Survey, Office of Hazardous Waste Hydrology, selected the former American Creosote Works site near Pensacola, Florida as a national research demonstration area. Seventy-nine years (1902-81) of seepage from unlined discharge impoundments had released creosote, diesel fuel, and pentachlorophenol (since 1950) wastes into the ground-water system. A cluster of from 2 to 5 wells constructed at different depths at 9 sites yielded water which revealed contamination 600 feet downgradient and to a depth of 100 feet below land surface near the site. The best cross-sectional representation of the contaminant plume was obtained from samples collected and analyzed for oxidation-reduction sensitive inorganic chemical constituents. Energy dispersive x-ray fluorescence detected recently formed iron carbonate in soil samples from highly reducing ground-water zones. Approximately eighty specific organic contaminants were isolated from ground-water samples by gas-chromotography/mass spectrometry. Column studies indicate the dimethyl phenols are not sorbed or degraded by the sand-and-gravel aquifer materials. Five of nineteen individual phenolic and related compounds are biodegradable based on anaerobic digestor experiments with ACW site bacterial populations. The potential impacts in the nearby Pensacola Bay biotic community are being evaluated. (USGS)

40 CFR 258.27 - Surface water requirements.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 26 2013-07-01 2013-07-01 false Surface water requirements. 258.27 Section 258.27 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES CRITERIA FOR MUNICIPAL SOLID WASTE LANDFILLS Operating Criteria § 258.27 Surface water requirements. MSWLF units shall not: (a) Cause a discharge of...

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dam, William; Gil, Dr. April; Johnson, Raymond H.

The US Department of Energy Office of Legacy Management (LM) is responsible for maintaining protective public health and environmental conditions at former uranium mill tailings sites nationwide via long-term stewardship. One of these sites, a former uranium mill near Riverton, Wyoming, is within the boundary of the Wind River Indian Reservation and operated from 1958 to 1963. Tailings and contaminated material associated with mill operations were removed and transported to an offsite disposal cell in 1989. The remedial action was completed under Title I of the Uranium Mill Tailings Radiation Control Act of 1978. Milling operations, which included an unlinedmore » tailings impoundment and an unlined evaporation pond, contaminated the shallow groundwater, resulting in a downgradient groundwater plume that discharges to the Little Wind River. A natural flushing compliance strategy was implemented in 1998. This strategy allows contaminants of concern to naturally flush from the groundwater, provided that contaminants flush below US Environmental Protection Agency maximum concentration limits within 100 years. As part of the compliance strategy, LM has implemented a groundwater monitoring program along with institutional controls that include the installation of an alternate water supply, continued sampling of private wells, and restrictions on well drilling and gravel pit construction. LM works closely with local stakeholders and community members to ensure that these institutional controls are in place and maintained. The Riverton site provides an interesting case study where contaminant remobilization due to river flooding prompted a reevaluation of the conceptual site model to verify if the current compliance strategy would remain protective of human health and the environment. Concentrations of groundwater contaminants, which include sulfate, molybdenum, and uranium, were transiently elevated following flooding of the Little Wind River in 2010 and 2016. These flood events provided the impetus to investigate other aspects of the hydrologic system, including the unsaturated zone, naturally reduced (sulfidic) zones, and evaporite deposits. New site conceptual models, field and laboratory studies, and numerical models are being developed to explain how biogeochemical sediment–water interactions contribute to plume persistence and flood-related increases in groundwater concentrations. Updated human health and ecological risk assessments are progressing to evaluate the risk to human health and the environment based on current site conditions. Groundwater concentrations may remain above US Environmental Protection Agency maximum concentration limits beyond the 100-year natural flushing regulatory time frame. LM in its capacity as a long-term steward continues to monitor the site to ensure protectiveness is maintained and to determine the feasibility of alternative compliance and remediation strategies.« less

Galvanic Liquid Applied Coating System for Protection of Embedded Steel Surfaces from Corrosion

NASA Technical Reports Server (NTRS)

Curran, Joseph; MacDowell, Louis; Voska, N. (Technical Monitor)

2002-01-01

The corrosion of reinforcing steel in concrete is an insidious problem for the Kennedy Space Center, government agencies, and the general public. Existing corrosion protection systems on the market are costly, complex, and time-consuming to install, require continuous maintenance and monitoring, and require specialized skills for installation. NASA's galvanic liquid-applied coating offers companies the ability to conveniently protect embedded steel rebar surfaces from corrosion. Liquid-applied inorganic galvanic coating contains one ore more of the following metallic particles: magnesium, zinc, or indium and may contain moisture attracting compounds that facilitate the protection process. The coating is applied to the outer surface of reinforced concrete so that electrical current is established between metallic particles and surfaces of embedded steel rebar; and electric (ionic) current is responsible for providing the necessary cathodic protection for embedded rebar surfaces.

The Lincolnshire Limestone — Hydrogeochemical evolution over a ten-year period

NASA Astrophysics Data System (ADS)

Edmunds, W. M.; Walton, N. R. G.

1983-02-01

In the Lincolnshire (Jurassic) Limestone of Britain, a sequence of hydrogeochemical processes along a 28-km flow line was defined in 1969. These processes include solution, redox and ion-exchange reactions, sulphate reduction and mixing with saline formation water. Resampling of the aquifer profile after 10 years has confirmed the overall sequence, although downgradient increases in both sulphate and calcium, together with changes in redox system, can be recognised. These changes are related to the migration of agrichemical pollutants and the results demonstrate that the aquifer must have a significant capacity for in situ nitrate reduction.

The combined use of 87Sr/86Sr and carbon and water isotopes to study the hydrochemical interaction between groundwater and lakewater in mantled karst

NASA Astrophysics Data System (ADS)

Katz, Brian G.; Bullen, Thomas D.

1996-12-01

The hydrochemical interaction between groundwater and lakewater influences the composition of water that percolates downward from the surficial aquifer system through the underlying intermediate confining unit and recharges the Upper Floridan aquifer along highlands in Florida. The 87Sr/86Sr ratio along with the stable isotopes, D, 18O, and 13C were used as tracers to study the interaction between groundwater, lakewater, and aquifer minerals near Lake Barco, a seepage lake in the mantled karst terrane of northern Florida. Upgradient from the lake, the 87Sr/86Sr ratio of groundwater decreases with depth (mean values of 0.71004, 0.70890, and 0.70852 for water from the surficial aquifer system, intermediate confining unit, and Upper Floridan aquifer, respectively), resulting from the interaction of dilute oxygenated recharge water with aquifer minerals that are less radiogenic with depth. The concentrations of Sr2+ generally increase with depth, and higher concentrations of Sr2+ in water from the Upper Floridan aquifer (20-35 μg/L), relative to water from the surficial aquifer system and the intermediate confining unit, result from the dissolution of Sr-bearing calcite and dolomite in the Eocene limestone. Dissolution of calcite [δ13C= -1.6permil(‰)] is also indicated by an enriched δ13CDIC(-8.8 to -11.4 ‰) in water from the Upper Floridan aquifer, relative to the overlying hydrogeologic units (δ13CDIC< -16‰). Groundwater downgradient from Lake Barco was enriched in18O and D relative to groundwater upgradient from the lake, indicating mixing of lakewater leakage and groundwater. Downgradient from the lake, the 87Sr/86Sr ratio of groundwater and aquifer material become less radiogenic and the Sr2+ concentrations generally increase with depth. However, Sr2+ concentrations are substantially less than in upgradient groundwaters at similar depths. The lower Sr2+ concentrations result from the influence of anoxic lakewater leakage on the mobility of Sr2+ from clays. Based on results from mass-balance modeling, it is probable that cation exchange plays the dominant role in controlling the 87Sr/86Sr ratio of groundwater, both upgradient and downgradient from Lake Barco. Even though groundwater from the three distinct hydrogeologic units displays considerable variability in Sr concentration and isotopic composition, the dominant processes associated with the mixing of lakewater leakage with groundwater, as well as the effects of mineral-water interaction, can be ascertained by integrating the use of stable and radiogenic isotopic measurements of groundwater, lakewater, and aquifer minerals.

Data Validation Package November 2015 Groundwater and Surface Water Sampling at the Old and New Rifle, Colorado, Processing Sites February 2016

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bush, Richard; Lemke, Peter

Water samples were collected from 36 locations at New Rifle and Old Rifle, Colorado, Processing Sites. Duplicate samples were collected from New Rifle locations 0659 and 0855, and Old Rifle location 0304. One equipment blank was collected after decontamination of non-dedicated equipment used to collect one surface water sample. Sampling and analyses were conducted as specified in the Sampling and Analysis Plan for U.S. Department of Energy Office of Legacy Management Sites (LMS/PRO/S04351, continually updated). New Rifle Site Samples were collected at the New Rifle site from 16 monitoring wells and 7 surface locations in compliance with the December 2008more » Groundwater Compliance Action Plan [GCAP] for the New Rifle, Colorado, Processing Site (LMS/RFN/S01920), with one exception: New Rifle location 0635 could not be sampled because it was inaccessible; a fence installed by the Colorado Department of Transportation prevents access to this location. DOE is currently negotiating access with the Colorado Department of Transportation. Analytes measured at the New Rifle site included contaminants of concern (COCs) (arsenic, molybdenum, nitrate + nitrite as nitrogen, selenium, uranium, and vanadium) ammonia as nitrogen, major cations, and major anions. Field measurements of total alkalinity, oxidation- reduction potential, pH, specific conductance, turbidity, and temperature were made at each location, and the water level was measured at each sampled well. A proposed alternate concentration limit (ACL) for vanadium of 50 milligrams per liter (mg/L), specific to the compliance (POC) wells (RFN-0217, -0659, -0664, and -0669) is included in the New Rifle GCAP. Vanadium concentrations in the POC wells were below the proposed ACL as shown in the time-concentration graphs in the Data Presentation section (Attachment 2). Time-concentration graphs from all other locations sampled are also included in Attachment 2. Sampling location RFN-0195 was misidentified for the June/August 2014 and November 2014 sampling events. (Well RFN-0609 was inadvertently sampled instead of RFN-0195 in 2014.) The results for RFN-0195 have been corrected, and are included in associated time-concentration graphs for this location. Recent results for RFN-0195 are consistent with established trends with the possible exception of vanadium. The most recent result for vanadium showed an increase over recent values. Vanadium concentrations at RFN-0195 and other locations will continue to be evaluated in the future to determine the potential for deviations from established trends. The surface water locations were sampled to monitor the impact of groundwater discharge. COC concentrations at Colorado River surface water locations RFN-0324 and RFN-0326, downgradient of the site, remained low and were consistent with historical results, as shown in the time-concentration graphs. COC concentrations did not indicate there are any impacts related to groundwater discharge to the river. In many cases, elevated COC concentrations at the New Rifle site pond locations were observed, as shown in the time-versus concentration graphs. As noted in the GCAP, this indicates impacts from groundwater discharge to the ponds. Old Rifle Site Samples were collected at the Old Rifle site from eight monitoring wells and five surface locations in compliance with the December 2001 Groundwater Compliance Action Plan for the Old Rifle, Colorado, UMTRA Project Site (GJ0-2000-177-TAR). Analytes measured at the Old Rifle site included COCs (selenium, uranium, and vanadium), major cations, and major anions. Field measurements of total alkalinity, oxidation-reduction potential, pH, specific conductance, turbidity, temperature, were made at each location, and the water level was measured at each sampled well. The monitoring strategy described in the GCAP is designed to determine progress of the natural flushing process in meeting compliance standards for site COCs. Standards for selenium and vanadium are the proposed ACLs of0.05 mg/L and 1.0 mg/L, respectively. For uranium the cleanup goal is the UMTRA standard of 0.044 mg/L or background, whichever is higher. As shown in the time concentration graphs, the uranium concentration exceeds the cleanup goal at groundwater monitoring locations RF0-0304, -0305, -0310, -0655, and -0656. The surface water locations were sampled to monitor the impact of groundwater discharge at Colorado River surface water locations adjacent to (RF0-0396) and downgradient of the site (RF0-0741). COC concentrations remain low and consistent with historical concentrations as shown in the time-concentration graphs (Attachment 2), which indicate no impacts from groundwater discharge to the river.« less

Total vertical sediment flux and PM10 emissions from disturbed Chihuahuan Desert Surfaces

USDA-ARS?s Scientific Manuscript database

Desert surfaces are typically stable and represent some of the oldest landforms on Earth. For surfaces without vegetation, the evolution of a desert pavements of gravel protects the surface from erosive forces and vegetation further protects the surface in arid and semi-arid rangelands. The suscep...

Durability Issues for the Protection of Materials from Atomic Oxygen Attack in Low Earth Orbit

NASA Astrophysics Data System (ADS)

Banks, B. A.; Lenczewski, M.; Demko, R.

2002-01-01

Low Earth orbital atomic oxygen is capable of eroding most polymeric materials typically used on spacecraft. Solar array blankets, thermal control polymers, and carbon fiber matrix composites are readily oxidized to become thinner and less capable of supporting the loads imposed upon them. Protective coatings have been developed that are or become durable to atomic oxygen to prevent oxidative erosion of the underlying polymers. However, the details of the chemistry, surface roughness and coating configuration can play a significant role as to whether or not the coating provides long duration atomic oxygen protection. Identical coatings on different surface roughness surfaces can produce drastically have drastically different durability results. Poor choice of protective coatings or self-protecting materials can also result in contamination of surrounding spacecraft surfaces. Such contamination can deposit on optical or thermal control surfaces resulting in changes in solar absorbtance, transmittance and reflectance of surfaces. Examples of successful and unsuccessful techniques used for atomic oxygen durability or protection will be presented based on actual results from low Earth orbital spacecraft. Investigations of the causes of undesired consequences or protective coating failures will be presented including ground laboratory experimental analysis as well as computational modeling. Atomic oxygen protective coating results from various low Earth orbital missions including the Long Duration Exposure Facility, the European Retrievable Carrier, Mir, and International Space Station will be presented to illustrate examples of protection successes as well as failures including analyses of the causes for the differences and proposed solutions.

75 FR 28861 - Walking-Working Surfaces and Personal Protective Equipment (Fall Protection Systems)

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-24

... workplaces walk or work on level surfaces, such as floors, where slips, trips, and falls are common..., and similar surfaces where slips, trips, or falls are likely to result in serious injury or death. The... receive a level of protection that is effective and necessary. OSHA believes many of these slips, trips...

Spray shadowing for stress relief and mechanical locking in thick protective coatings

DOEpatents

Hollis, Kendall [Los Alamos, NM; Bartram, Brian [Los Alamos, NM

2007-05-22

A method for applying a protective coating on an article, comprising the following steps: selecting an article with a surface for applying a coating thickness; creating undercut grooves on the article, where the grooves depend beneath the surface to a bottom portion with the grooves having an upper width on the surface and a lower width on the bottom portion connected by side walls, where at least one of the side walls connects the upper width and the lower width to form an undercut angle with the surface less than 90.degree.; and, applying the protective coating onto the article to fill the undercut grooves and cover the surface, thereby forming weak paths within the protective coating.

Isotopic and geochemical tracers for U(VI) reduction and U mobility at an in situ recovery U mine

DOE PAGES

Basu, Anirban; Brown, Shaun T.; Christensen, John N.; ...

2015-05-19

In situ recovery (ISR) uranium (U) mining mobilizes U in its oxidized hexavalent form (U(VI)) by oxidative dissolution of U from the roll-front U deposits. Post-mining natural attenuation of residual U(VI) at ISR mines is a potential remediation strategy. Detection and monitoring of naturally occurring reducing subsurface environments are important for successful implementation of this remediation scheme. We used the isotopic tracers ²³⁸U/²³⁵U (δ²³⁸U), ²³⁴U/²³⁸U activity ratio, and ³⁴S/³²S (δ³⁴S), and geochemical measurements of U ore and groundwater collected from 32 wells located within, upgradient, and downgradient of a roll-front U deposit to detect U(VI) reduction and U mobility atmore » an ISR mining site at Rosita, TX, USA. The δ²³⁸U in Rosita groundwater varies from 0.61‰ to -2.49‰, with a trend toward lower δ²³⁸U in downgradient wells. The concurrent decrease in U(VI) concentration and δ²³⁸U with an ε of 0.48‰ ± 0.08‰ is indicative of naturally occurring reducing environments conducive to U(VI) reduction. Additionally, characteristic ²³⁴U/²³⁸U activity ratio and δ³⁴S values may also be used to trace the mobility of the ore zone groundwater after mining has ended. These results support the use of U isotope-based detection of natural attenuation of U(VI) at Rosita and other similar ISR mining sites.« less

Effect of Water-Table Fluctuations on Source Depletion and Dissolved-Plume Behavior of a Multi-Component Light Nonaqueous-Phase Liquid

NASA Astrophysics Data System (ADS)

Dobson, R.; Schroth, M. H.; Zeyer, J.

2006-12-01

Light nonaqueous-phase liquids (LNAPLs) such as gasoline and diesel are among the most common soil and groundwater contaminants. Dissolution and subsequent advective transport of LNAPL components can negatively impact downgradient water supplies, while biodegradation is commonly thought to be an important sink for this class of contaminants. Water-table fluctuations, either naturally occurring or intentionally induced, may affect LNAPL component transport and biodegradation in aquifers. We present a laboratory investigation of the effect of water-table fluctuations on the dissolution and biodegradation of a multi-component LNAPL in a pair of similar model aquifers, one of which was subjected to a water-table fluctuation. Water-table fluctuation resulted in LNAPL and air entrapment below the water table, an increase in the vertical extent of LNAPL contamination and an increase in the volume of water passing through the contaminated zone. Effluent concentrations of dissolved LNAPL components were higher and those of dissolved nitrate were lower in the aquifer model where a fluctuation had been induced. Thus, water table fluctuation led to enhanced LNAPL dissolution as well as enhanced biodegradation activity. The increase in biodegradation observed after fluctuation was of lesser magnitude than the increase in LNAPL dissolution, such that water-table fluctuations might be expected to result in increased exposure of downgradient receptors to dissolved LNAPL components. Conversely, the potential for free-phase LNAPL migration was reduced following a water-table fluctuation, as LNAPL entrapment by the rising water table reduced the amount of free phase LNAPL. Lateral migration of LNAPL following emplacement was observed in the model aquifer where no fluctuation occurred, but not in the model aquifer where a water-table fluctuation was induced.

Chemical evolution of groundwater near a sinkhole lake, northern Florida: 1. Flow patterns, age of groundwater, and influence of lakewater leakage

USGS Publications Warehouse

Katz, Brian G.; Lee, Terrie M.; Plummer, Niel; Busenberg, Eurybiades

1995-01-01

Leakage from sinkhole lakes significantly influences recharge to the Upper Floridan aquifer in poorly confined sediments in northern Florida. Environmental isotopes (oxygen 18, deuterium, and tritium), chlorofluorocarbons (CFCs: CFC-11, CCl3F; CFC-12, CCl2F2; and CFC-113, C2Cl3F3), and solute tracers were used to investigate groundwater flow patterns near Lake Barco, a seepage lake in a mantled karst setting in northern Florida. Stable isotope data indicated that the groundwater downgradient from the lake contained 11–67% lake water leakage, with a limit of detection of lake water in groundwater of 4.3%. The mixing fractions of lake water leakage, which passed through organic-rich sediments in the lake bottom, were directly proportional to the observed methane concentrations and increased with depth in the groundwater flow system. In aerobic groundwater upgradient from Lake Barco, CFC-modeled recharge dates ranged from 1987 near the water table to the mid 1970s for water collected at a depth of 30 m below the water table. CFC-modeled recharge dates (based on CFC-12) for anaerobic groundwater downgradient from the lake ranged from the late 1950s to the mid 1970s and were consistent with tritium data. CFC-modeled recharge dates based on CFC-11 indicated preferential microbial degradation in anoxic waters. Vertical hydraulic conductivities, calculated using CFC-12 modeled recharge dates and Darcy's law, were 0.17, 0.033, and 0.019 m/d for the surficial aquifer, intermediate confining unit, and lake sediments, respectively. These conductivities agreed closely with those used in the calibration of a three-dimensional groundwater flow model for transient and steady state flow conditions.

Evaluation of volatilization as a natural attenuation pathway for MTBE

USGS Publications Warehouse

Lahvis, Matthew A.; Baehr, Arthur L.; Baker, Ronald J.

2004-01-01

Volatilization and diffusion through the unsaturated zone can be an important pathway for natural attenuation remediation of methyl tert-butyl ether (MTBE) at gasoline spill sites. The significance of this pathway depends primarily on the distribution of immiscible product within the unsaturated zone and the relative magnitude of aqueous-phase advection (ground water recharge) to gaseous-phase diffusion. At a gasoline spill site in Laurel Bay, South Carolina, rates of MTBE volatilization from ground water downgradient from the source are estimated by analyzing the distribution of MTBE in the unsaturated zone above a solute plume. Volatilization rates of MTBE from ground water determined by transport modeling ranged from 0.0020 to 0.0042 g m-2/year, depending on the assumed rate of ground water recharge. Although diffusive conditions at the Laurel Bay site are favorable for volatilization, mass loss of MTBE is insignificant over the length (230 m) of the solute plume. Based on this analysis, significant volatilization of MTBE from ground water downgradient from source areas at other sites is not likely. In contrast, model results indicate that volatilization coupled with diffusion to the atmosphere could be a significant mass loss pathway for MTBE in source areas where residual product resides above the capillary zone. Although not documented, mass loss of MTBE at the Laurel Bay site due to volatilization and diffusion to the atmosphere are predicted to be two to three times greater than mass loading of MTBE to ground water due to dissolution and recharge. This result would imply that volatilization in the source zone may be the critical natural attenuation pathway for MTBE at gasoline spill sites, especially when considering capillary zone limitations on volatilization of MTBE from ground water and the relative recalcitrance of MTBE to biodegradation.

The Apache Longbow-Hellfire Missile Test at Yuma Proving Ground: Ecological Risk Assessment for Tracked Vehicle Movement across Desert Pavement

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peterson, Mark J; Efroymson, Rebecca Ann; Hargrove, William Walter

A multiple stressor risk assessment was conducted at Yuma Proving Ground, Arizona, as a demonstration of the Military Ecological Risk Assessment Framework. The focus was a testing program at Cibola Range, which involved an Apache Longbow helicopter firing Hellfire missiles at moving targets, M60-A1 tanks. This paper describes the ecological risk assessment for the tracked vehicle movement component of the testing program. The principal stressor associated with tracked vehicle movement was soil disturbance, and a resulting, secondary stressor was hydrological change. Water loss to washes and wash vegetation was expected to result from increased infiltration and/or evaporation associated with disturbancesmore » to desert pavement. The simulated exposure of wash vegetation to water loss was quantified using estimates of exposed land area from a digital ortho quarter quad aerial photo and field observations, a 30 30 m digital elevation model, the flow accumulation feature of ESRI ArcInfo, and a two-step process in which runoff was estimated from direct precipitation to a land area and from water that flowed from upgradient to a land area. In all simulated scenarios, absolute water loss decreased with distance from the disturbance, downgradient in the washes; however, percentage water loss was greatest in land areas immediately downgradient of a disturbance. Potential effects on growth and survival of wash trees were quantified by using an empirical relationship derived from a local unpublished study of water infiltration rates. The risk characterization concluded that neither risk to wash vegetation growth or survival nor risk to mule deer abundance and reproduction was expected. The risk characterization was negative for both the incremental risk of the test program and the combination of the test and pretest disturbances.« less

Refining the site conceptual model at a former uranium mill site in Riverton, Wyoming, USA

DOE PAGES

Dam, William; Campbell, Sam; Johnson, Ray; ...

2015-07-07

Milling activities at a former uranium mill site near Riverton, Wyoming, USA, contaminated the shallow groundwater beneath and downgradient of the site. Although the mill operated for <6 years (1958-1963), its impact remains an environmental liability. Groundwater modeling predicted that contaminant concentrations were declining steadily, which confirmed the conceptual site model (CSM). However, local flooding in 2010 mobilized contaminants that migrated downgradient from the Riverton site and resulted in a dramatic increase in groundwater contaminant concentrations. This observation indicated that the original CSM was inadequate to explain site conditions and needed to be refined. In response to the new observationsmore » after the flood, a collaborative investigation to better understand site conditions and processes commenced. This investigation included installing 103 boreholes to collect soil and groundwater samples, sampling and analysis of evaporite minerals along the bank of the Little Wind River, an analysis of evaportranspiration in the shallow aquifer, and sampling naturally organic-rich sediments near groundwater discharge areas. The enhanced characterization revealed that the existing CSM did not account for high uranium concentrations in groundwater remaining on the former mill site and groundwater plume stagnation near the Little Wind River. Observations from the flood and subsequent investigations indicate that additional characterization is still needed to continue refining the CSM and determine the viability of the natural flushing compliance strategy. Additional sampling, analysis, and testing of soil and groundwater are necessary to investigate secondary contaminant sources, mobilization of contaminants during floods, geochemical processes, contaminant plume stagnation, distribution of evaporite minerals and organic-rich sediments, and mechanisms and rates of contaminant transfer from soil to groundwater. Future data collection will be used to continually revise the CSM and evaluate the compliance strategy at the site.« less

Steroid estrogens, nonylphenol ethoxylate metabolites, and other wastewater contaminants in groundwater affected by a residential septic system on Cape Cod, MA.

PubMed

Swartz, Christopher H; Reddy, Sharanya; Benotti, Mark J; Yin, Haifei; Barber, Larry B; Brownawell, Bruce J; Rudel, Ruthann A

2006-08-15

Septic systems serve approximately 25% of U.S. households and may be an important source of estrogenic and other organic wastewater contaminants (OWC) to groundwater. We monitored several estrogenic OWC, including nonylphenol (NP), nonylphenol mono- and diethoxycarboxylates (NP1EC and NP2EC), the steroid hormones 17beta-estradiol (E2), estrone (E1) and their glucuronide and sulfate conjugates, and other OWC such as methylene blue active substances (MBAS), caffeine and its degradation product paraxanthine, and two fluorescent whitening agents in a residential septic system and in downgradient groundwater. E1 and E2 were present predominantly as free estrogens in groundwater, and near-source groundwater concentrations of all OWC were highest in the suboxic to anoxic portion of the wastewater plume, where concentrations of most OWC were similar to those observed in the septic tank on the same day. NP and NP2EC were up to 6- to 30-fold higher, and caffeine and paraxanthine were each 60-fold lower than septic tank concentrations, suggesting net production and removal, respectively, of these constituents. At the most shallow, oxic depth, concentrations of all OWC except for NP2EC were substantially lower than in the tank and in deeper wells. Yet boron, specific conductance, and the sum of nitrate-and ammonia-nitrogen were highest at this shallow depth, suggesting preferential losses of OWC along the more oxic flow lines. As far as 6.0 m downgradient, concentrations of many OWC were within a factor of 2 of near-source concentrations. The results suggest that there is the potential for migration of these OWC, which are unregulated and not routinely monitored, in groundwater.

Steroid estrogens, nonylphenol ethoxylate metabolites, and other wastewater contaminants in groundwater affected by a residential septic system on cape cod, MA

USGS Publications Warehouse

Swartz, C.H.; Reddy, S.; Benotti, M.J.; Yin, H.; Barber, L.B.; Brownawell, Bruce J.; Rudel, R.A.

2006-01-01

Septic systems serve approximately 25% of U.S. households and may be an important source of estrogenic and other organic wastewater contaminants (OWC) to groundwater. We monitored several estrogenic OWC, including nonylphenol (NP), nonylphenol mono- and diethoxycarboxylates (NP1EC and NP2EC), the steroid hormones 17??-estradiol (E2), estrone (E1) and their glucuronide and sulfate conjugates, and other OWC such as methylene blue active substances (MBAS), caffeine and its degradation product paraxanthine, and two fluorescent whitening agents in a residential septic system and in downgradient groundwater. E1 and E2 were present predominantly as free estrogens in groundwater, and near-source groundwater concentrations of all OWC were highest in the suboxic to anoxic portion of the wastewater plume, where concentrations of most OWC were similar to those observed in the septic tank on the same day. NP and NP2EC were up to 6- to 30-fold higher, and caffeine and paraxanthine were each 60-fold lower than septic tank concentrations, suggesting net production and removal, respectively, of these constituents. At the most shallow, oxic depth, concentrations of all OWC except for NP2EC were substantially lower than in the tank and in deeper wells. Yet boron, specific conductance, and the sum of nitrate-and ammonia-nitrogen were highest at this shallow depth, suggesting preferential losses of OWC along the more oxic flow lines. As far as 6.0 m downgradient, concentrations of many OWC were within a factor of 2 of near-source concentrations. The results suggest that there is the potential for migration of these OWC, which are unregulated and not routinely monitored, in groundwater. ?? 2006 American Chemical Society.

Use of plume mapping data to estimate chlorinated solvent mass loss

USGS Publications Warehouse

Barbaro, J.R.; Neupane, P.P.

2006-01-01

Results from a plume mapping study from November 2000 through February 2001 in the sand-and-gravel surficial aquifer at Dover Air Force Base, Delaware, were used to assess the occurrence and extent of chlorinated solvent mass loss by calculating mass fluxes across two transverse cross sections and by observing changes in concentration ratios and mole fractions along a longitudinal cross section through the core of the plume. The plume mapping investigation was conducted to determine the spatial distribution of chlorinated solvents migrating from former waste disposal sites. Vertical contaminant concentration profiles were obtained with a direct-push drill rig and multilevel piezometers. These samples were supplemented with additional ground water samples collected with a minipiezometer from the bed of a perennial stream downgradient of the source areas. Results from the field program show that the plume, consisting mainly of tetrachloroethylene (PCE), trichloroethene (TCE), and cis-1,2-dichloroethene (cis-1,2-DCE), was approximately 670 m in length and 120 m in width, extended across much of the 9- to 18-m thickness of the surficial aquifer, and discharged to the stream in some areas. The analyses of the plume mapping data show that losses of the parent compounds, PCE and TCE, were negligible downgradient of the source. In contrast, losses of cis-1,2-DCE, a daughter compound, were observed in this plume. These losses very likely resulted from biodegradation, but the specific reaction mechanism could not be identified. This study demonstrates that plume mapping data can be used to estimate the occurrence and extent of chlorinated solvent mass loss from biodegradation and assess the effectiveness of natural attenuation as a remedial measure.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dam, William; Campbell, Sam; Johnson, Ray

Milling activities at a former uranium mill site near Riverton, Wyoming, USA, contaminated the shallow groundwater beneath and downgradient of the site. Although the mill operated for <6 years (1958-1963), its impact remains an environmental liability. Groundwater modeling predicted that contaminant concentrations were declining steadily, which confirmed the conceptual site model (CSM). However, local flooding in 2010 mobilized contaminants that migrated downgradient from the Riverton site and resulted in a dramatic increase in groundwater contaminant concentrations. This observation indicated that the original CSM was inadequate to explain site conditions and needed to be refined. In response to the new observationsmore » after the flood, a collaborative investigation to better understand site conditions and processes commenced. This investigation included installing 103 boreholes to collect soil and groundwater samples, sampling and analysis of evaporite minerals along the bank of the Little Wind River, an analysis of evaportranspiration in the shallow aquifer, and sampling naturally organic-rich sediments near groundwater discharge areas. The enhanced characterization revealed that the existing CSM did not account for high uranium concentrations in groundwater remaining on the former mill site and groundwater plume stagnation near the Little Wind River. Observations from the flood and subsequent investigations indicate that additional characterization is still needed to continue refining the CSM and determine the viability of the natural flushing compliance strategy. Additional sampling, analysis, and testing of soil and groundwater are necessary to investigate secondary contaminant sources, mobilization of contaminants during floods, geochemical processes, contaminant plume stagnation, distribution of evaporite minerals and organic-rich sediments, and mechanisms and rates of contaminant transfer from soil to groundwater. Future data collection will be used to continually revise the CSM and evaluate the compliance strategy at the site.« less

Chemical Evolution of Groundwater Near a Sinkhole Lake, Northern Florida: 1. Flow Patterns, Age of Groundwater, and Influence of Lake Water Leakage

NASA Astrophysics Data System (ADS)

Katz, Brian G.; Lee, Terrie M.; Plummer, L. Niel; Busenberg, Eurybiades

1995-06-01

Leakage from sinkhole lakes significantly influences recharge to the Upper Floridan aquifer in poorly confined sediments in northern Florida. Environmental isotopes (oxygen 18, deuterium, and tritium), chlorofluorocarbons (CFCs: CFC-11, CCl3F; CFC-12, CCl2F2; and CFC-113, C2Cl3F3), and solute tracers were used to investigate groundwater flow patterns near Lake Barco, a seepage lake in a mantled karst setting in northern Florida. Stable isotope data indicated that the groundwater downgradient from the lake contained 11-67% lake water leakage, with a limit of detection of lake water in groundwater of 4.3%. The mixing fractions of lake water leakage, which passed through organic-rich sediments in the lake bottom, were directly proportional to the observed methane concentrations and increased with depth in the groundwater flow system. In aerobic groundwater upgradient from Lake Barco, CFC-modeled recharge dates ranged from 1987 near the water table to the mid 1970s for water collected at a depth of 30 m below the water table. CFC-modeled recharge dates (based on CFC-12) for anaerobic groundwater downgradient from the lake ranged from the late 1950s to the mid 1970s and were consistent with tritium data. CFC-modeled recharge dates based on CFC-11 indicated preferential microbial degradation in anoxic waters. Vertical hydraulic conductivities, calculated using CFC-12 modeled recharge dates and Darcy's law, were 0.17, 0.033, and 0.019 m/d for the surficial aquifer, intermediate confining unit, and lake sediments, respectively. These conductivities agreed closely with those used in the calibration of a three-dimensional groundwater flow model for transient and steady state flow conditions.

Time-lapse 3-D electrical resistance tomography inversion for crosswell monitoring of dissolved and supercritical CO 2 flow at two field sites: Escatawpa and Cranfield, Mississippi, USA

DOE PAGES

Commer, Michael; Doetsch, Joseph; Dafflon, Baptiste; ...

2016-06-01

In this study, we advance the understanding of three-dimensional (3-D) electrical resistivity tomography (ERT) for monitoring long-term CO 2 storage by analyzing two previously published field time-lapse data sets. We address two important aspects of ERT inversion-the issue of resolution decay, a general impediment to the ERT method, and the issue of potentially misleading imaging artifacts due to 2-D model assumptions. The first study analyzes data from a shallow dissolved-CO 2 injection experiment near Escatawpa (Mississippi), where ERT data were collected in a 3-D crosswell configuration. Here, we apply a focusing approach designed for crosswell configurations to counteract resolution lossmore » in the inter-wellbore area, with synthetic studies demonstrating its effectiveness. The 3-D field data analysis reveals an initially southwards-trending flow path development and a dispersing plume development in the downgradient inter-well region. The second data set was collected during a deep (over 3 km) injection of supercritical CO 2 near Cranfield (Mississippi). Comparative 2-D and 3-D inversions reveal the projection of off-planar anomalies onto the cross-section, a typical artifact introduced by 2-D model assumptions. Conforming 3-D images from two different algorithms support earlier hydrological investigations, indicating a conduit system where flow velocity variations lead to a circumvention of a close observation well and an onset of increased CO 2 saturation downgradient from this well. We relate lateral permeability variations indicated by an independently obtained hydrological analysis to this consistently observed pattern in the CO 2 spatial plume evolution.« less

Herbicide loading to shallow ground water beneath Nebraska's Management Systems Evaluation Area.

PubMed

Spalding, Roy F; Watts, Darrell G; Snow, Daniel D; Cassada, David A; Exner, Mary E; Schepers, James S

2003-01-01

Better management practices can counter deterioration of ground water quality. From 1991 through 1996 the influence of improved irrigation practices on ground water pesticide contamination was assessed at the Nebraska Management Systems Evaluation Area. Three 13.4-ha corn (Zea mays L.) fields were studied: a conventional furrow-irrigated field, a surge-irrigated field and a center pivot-irrigated field, and a center pivot-irrigated alfalfa (Medicago sativa L.) field. The corn fields received one identical banded application of Bicep (atrazine [6-chloro-N-ethyl-N'-(1-methylethyl)-1,3,5-triazine-2,4,-diamine] + metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl) acetamidel) annually; the alfalfa field was untreated. Ground water samples were collected three times annually from 16 depths of 31 multilevel samplers. Six years of sample data indicated that a greater than 50% reduction in irrigation water on the corn management fields lowered average atrazine concentrations in the upper 1.5 m of the aquifer downgradient of the corn fields from approximately 5.5 to <0.5 microg L(-1). Increases in deethylatrazine (DEA; 2-chloro-4-amino-6-isopropylamino-s-triazine) to atrazine molar ratios indicated that reducing water applications enhanced microbial degradation of atrazine in soil zones. The occurrence of peak herbicide loading in ground water was unpredictable but usually was associated with heavy precipitation within days of herbicide application. Focused recharge of storm runoff that ponded in the surge-irrigated field drainage ditch, in the upgradient road ditch, and at the downgradient end of the conventionally irrigated field was a major mechanism for vertical transport. Sprinkler irrigation technology limited areas for focused recharge and promoted significantly more soil microbial degradation of atrazine than furrow irrigation techniques and, thereby, improved ground water quality.

Isotopic and geochemical tracers for U(VI) reduction and U mobility at an in situ recovery U mine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Basu, Anirban; Brown, Shaun T.; Christensen, John N.

In situ recovery (ISR) uranium (U) mining mobilizes U in its oxidized hexavalent form (U(VI)) by oxidative dissolution of U from the roll-front U deposits. Post-mining natural attenuation of residual U(VI) at ISR mines is a potential remediation strategy. Detection and monitoring of naturally occurring reducing subsurface environments are important for successful implementation of this remediation scheme. We used the isotopic tracers ²³⁸U/²³⁵U (δ²³⁸U), ²³⁴U/²³⁸U activity ratio, and ³⁴S/³²S (δ³⁴S), and geochemical measurements of U ore and groundwater collected from 32 wells located within, upgradient, and downgradient of a roll-front U deposit to detect U(VI) reduction and U mobility atmore » an ISR mining site at Rosita, TX, USA. The δ²³⁸U in Rosita groundwater varies from 0.61‰ to -2.49‰, with a trend toward lower δ²³⁸U in downgradient wells. The concurrent decrease in U(VI) concentration and δ²³⁸U with an ε of 0.48‰ ± 0.08‰ is indicative of naturally occurring reducing environments conducive to U(VI) reduction. Additionally, characteristic ²³⁴U/²³⁸U activity ratio and δ³⁴S values may also be used to trace the mobility of the ore zone groundwater after mining has ended. These results support the use of U isotope-based detection of natural attenuation of U(VI) at Rosita and other similar ISR mining sites.« less

Patterns of entrapped air dissolution in a two-dimensional pilot-scale synthetic aquifer.

PubMed

McLeod, Heather C; Roy, James W; Smith, James E

2015-01-01

Past studies of entrapped air dissolution have focused on one-dimensional laboratory columns. Here the multidimensional nature of entrapped air dissolution was investigated using an indoor tank (180 × 240 × 600 cm(3) ) simulating an unconfined sand aquifer with horizontal flow. Time domain reflectometry (TDR) probes directly measured entrapped air contents, while dissolved gas conditions were monitored with total dissolved gas pressure (PTDG ) probes. Dissolution occurred as a diffuse wedge-shaped front from the inlet downgradient, with preferential dissolution at depth. This pattern was mainly attributed to increased gas solubility, as shown by PTDG measurements. However, compression of entrapped air at greater depths, captured by TDR and leading to lower quasi-saturated hydraulic conductivities and thus greater velocities, also played a small role. Linear propagation of the dissolution front downgradient was observed at each depth, with both TDR and PTDG , with increasing rates with depth (e.g, 4.1 to 5.7× slower at 15 cm vs. 165 cm depth). PTDG values revealed equilibrium with the entrapped gas initially, being higher at greater depth and fluctuating with the barometric pressure, before declining concurrently with entrapped air contents to the lower PTDG of the source water. The observed dissolution pattern has long-term implications for a wide variety of groundwater management issues, from recharge to contaminant transport and remediation strategies, due to the persistence of entrapped air near the water table (potential timescale of years). This study also demonstrated the utility of PTDG probes for simple in situ measurements to detect entrapped air and monitor its dissolution. © 2014 Her Majesty the Queen in Right of Canada Groundwater © 2014, National Ground Water Association.

MER surface fault protection system

NASA Technical Reports Server (NTRS)

Neilson, Tracy

2005-01-01

The Mars Exploration Rovers surface fault protection design was influenced by the fact that the solar-powered rovers must recharge their batteries during the day to survive the night. the rovers needed to autonomously maintain thermal stability, initiate safe and reliable communication with orbiting assets or directly to Earth, while maintaining energy balance. This paper will describe the system fault protection design for the surface phase of the mission.

Effect of sewage sludge on formation of acidic ground water at a reclaimed coal mine

USGS Publications Warehouse

Cravotta, C.A.

1998-01-01

Data on rock, ground water, vadose water, and vadose gas chemistry were collected for two years after sewage sludge was applied at a reclaimed surface coal mine in Pennsylvania to determine if surface-applied sludge is an effective barrier to oxygen influx, contributes metals and nutrients to ground water, and promotes the acidification of ground water. Acidity, sulfate, and metals concentrations were elevated in the ground water (6- to 21-m depth) from spoil relative to unmined rock because of active oxidation of pyrite and dissolution of aluminosilicate, carbonate, and Mn-Fe-oxide minerals in the spoil. Concentrations of acidity, sulfate, metals (Fe, Mn, Al, Cd, Cu, Cr, Ni, Zn), and nitrate, and abundances of iron-oxidizing bacteria were elevated in the ground water from sludge-treated spoil relative to untreated spoil having a similar mineral composition; however, gaseous and dissolved oxygen concentrations did not differ between the treatments. Abundances of iron-oxidizing bacteria in the ground water samples were positively correlated with concentrations of ammonia, nitrate, acidity, metals, and sulfate. Concentrations of metals in vadose water samples (<5-m depth) from sludge-treated spoil (pH 5.9) were not elevated relative to untreated spoil (pH 4.4). In contrast, concentrations of nitrate were elevated in vadose water samples from sludge-treated spoil, frequently exceeding 10 mg/L. Downgradient decreases in nitrate to less than 3 mg/L and increases in sulfate concentrations in underlying ground water could result from oxidation of pyrite by nitrate. Thus, sewage sludge added to pyritic spoil can increase the growth of iron-oxidizing bacteria, the oxidation of pyrite, and the acidification of ground water. Nevertheless, the overall effects on ground water chemistry from the sludge were small and probably short-lived relative to the effects from mining only.

Thin film heater for removable volatile protecting coatings.

PubMed

Karim, Abid

2013-01-01

Freshly coated aluminum mirrors have excellent reflectivity at far ultraviolet wavelengths. However, reflectivity rapidly degrades when the mirror surfaces are exposed to atmosphere. In order to avoid this problem, freshly coated aluminum surface can be protected by over-coating of a removable volatile protecting coating. This protecting coating can be re-evaporated by controlled heating or by some other methods when required. This type of removable coating has immediate application in UV space astronomy. The purpose of this paper is to demonstrate the feasibility of re-evaporation of removable volatile Zn protecting coating using a NiCr thin film heater without affecting the reflection properties of Al mirror surfaces.

40 CFR 761.372 - Specific requirements for relatively clean surfaces.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Specific requirements for relatively clean surfaces. 761.372 Section 761.372 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT POLYCHLORINATED BIPHENYLS (PCBs) MANUFACTURING, PROCESSING...

40 CFR 61.344 - Standards: Surface impoundments.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 9 2012-07-01 2012-07-01 false Standards: Surface impoundments. 61.344 Section 61.344 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS National Emission Standard for Benzene...

40 CFR 61.344 - Standards: Surface impoundments.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 8 2010-07-01 2010-07-01 false Standards: Surface impoundments. 61.344 Section 61.344 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS National Emission Standard for Benzene...

Protected electrode structures and methods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mikhaylik, Yuriy V.; Laramie, Michael G.; Kopera, John Joseph Christopher

2017-08-08

An electrode structure and its method of manufacture are disclosed. The disclosed electrode structures may be manufactured by depositing a first release layer on a first carrier substrate. A first protective layer may be deposited on a surface of the first release layer and a first electroactive material layer may then be deposited on the first protective layer. The first release layer may have a low mean peak to valley surface roughness, which may enable the formation of a thin protective layer with a low mean peak to valley surface roughness.

Method for smoothing the surface of a protective coating

DOEpatents

Sangeeta, D.; Johnson, Curtis Alan; Nelson, Warren Arthur

2001-01-01

A method for smoothing the surface of a ceramic-based protective coating which exhibits roughness is disclosed. The method includes the steps of applying a ceramic-based slurry or gel coating to the protective coating surface; heating the slurry/gel coating to remove volatile material; and then further heating the slurry/gel coating to cure the coating and bond it to the underlying protective coating. The slurry/gel coating is often based on yttria-stabilized zirconia, and precursors of an oxide matrix. Related articles of manufacture are also described.

Method of coating metal surfaces to form protective metal coating thereon

DOEpatents

Krikorian, Oscar H.; Curtis, Paul G.

1992-01-01

A process is disclosed for forming a protective metal coating on a metal surface using a flux consisting of an alkali metal fluoride, an alkaline earth metal fluoride, an alkali metal fluoaluminate, an alkali metal fluosilicate, and mixtures thereof. The flux, in particulate form, is mixed with particles of a metal coating material which may comprise aluminum, chromium, mixtures thereof, and alloys containing at least 50 wt. % aluminum and the particulate mixture is applied to the metal surface in a single step, followed by heating the coated metal surface to a temperature sufficient to cause the metal coating material to react with the metal surface to form a protective reaction product in the form of a metal coating bonded to the metal surface. The metal surface which reacts with the metal coating material to form the protective coating may comprise Fe, Co, Ni, Ti, V, Cr, Mn, Zr, Nb, Mo, Tc, Hf, Ta, W, Re and alloys thereof.

Method of coating metal surfaces to form protective metal coating thereon

DOEpatents

Krikorian, O.H.; Curtis, P.G.

1992-03-31

A process is disclosed for forming a protective metal coating on a metal surface using a flux consisting of an alkali metal fluoride, an alkaline earth metal fluoride, an alkali metal fluoaluminate, an alkali metal fluosilicate, and mixtures thereof. The flux, in particulate form, is mixed with particles of a metal coating material which may comprise aluminum, chromium, mixtures thereof, and alloys containing at least 50 wt. % aluminum and the particulate mixture is applied to the metal surface in a single step, followed by heating the coated metal surface to a temperature sufficient to cause the metal coating material to react with the metal surface to form a protective reaction product in the form of a metal coating bonded to the metal surface. The metal surface which reacts with the metal coating material to form the protective coating may comprise Fe, Co, Ni, Ti, V, Cr, Mn, Zr, Nb, Mo, Tc, Hf, Ta, W, Re and alloys thereof. 1 figure.

Pluto's Paleoglaciation: Processes and Bounds

NASA Astrophysics Data System (ADS)

Umurhan, Orkan; Howard, Alan D.; White, Oliver L.; Moore, Jeffrey M.; Grundy, William M.; Schenk, Paul M.; Beyer, Ross A.; McKinnon, William B.; Singer, Kelsi N.; Lauer, Tod R.; Cheng, Andrew F.; Stern, S. Alan; Weaver, Harold A.; Young, Leslie; Ennico, Kimberly; Olkin, Catherine; New Horizons Science Team

2017-10-01

New Horizons imaging of Pluto’s surface shows eroded landscapes reminiscent of assorted glaciated terrains found on the Earth such as alpine valleys, dendritic networks and others. For example, LORRI imaging of fluted craters show radially oriented ridging which also resembles Pluto’s washboard terrain. Digital elevation modeling indicates that these down-gradient oriented ridges are about 3-4 km spaced apart with depths ranging from 0.2-0.5 km. Present day glaciation on Pluto is characterized by moving N2 ice blocks presumably riding over a H2O ice bedrock substrate. Assuming Pluto’s ancient surface was sculpted by N2 glaciation, what remains a mystery is the specific nature of the glacial erosion mechanism(s) responsible for the observed features.To better resolve this puzzle, we perform landform evolution modeling of several glacial erosion processes known from terrestrial H2O ice glaciation studies. These terrestrial processes, which depend upon whether or not the glacier’s base is wet or dry, include quarrying/plucking and fluvial erosion. We also consider new erosional processes (to be described in this presentation) which are unique to the highly insulating character of solid N2 including both phase change induced hydrofracture and geothermally driven basal melt. Until improvements in our knowledge of solid N2’s rheology are made available (including its mechanical behavior as a binary/trinary mixture of CH4 and CO), it is difficult to assess with high precision which of the aforementioned erosion mechanisms are responsible for the observed surface etchings.Nevertheless, we consider a model crater surface and examine its erosional development due to flowing N2 glacial ice as built up over time according to N2 deposition rates based on GCM modeling of Pluto’s ancient atmosphere. For given erosional mechanism our aim is to determine the permissible ranges of model input parameters (e.g., ice strength, flow rates, grain sizes, quarrying rates, etc.) that best reproduces the observed length scales found on the observed fluted craters. As of the writing of this abstract, both the processes of quarrying and phase change induced hydrofracture appear to be most promising at explaining the fluted crater ridging.

Pluto's Paleoglaciation: Processes and Bounds.

NASA Astrophysics Data System (ADS)

Umurhan, O. M.; Howard, A. D.; White, O. L.; Moore, J. M.; Grundy, W. M.; Schenk, P.; Beyer, R. A.; McKinnon, W. B.; Singer, K. N.; Lauer, T.; Cheng, A. F.; Stern, A.; Weaver, H. A., Jr.; Young, L. A.; Ennico Smith, K.; Olkin, C.

2017-12-01

New Horizons imaging of Pluto's surface shows eroded landscapes reminiscent of assorted glaciated terrains found on the Earth such as alpine valleys, dendritic networks and others. For example, LORRI imaging of fluted craters show radially oriented ridging which also resembles Pluto's washboard terrain. Digital elevation modeling indicates that these down-gradient oriented ridges are about 3-4 km spaced apart with depths ranging from 0.2-0.5 km. Present day glaciation on Pluto is characterized by moving N2 ice blocks presumably riding over a H2O ice bedrock substrate. Assuming Pluto's ancient surface was sculpted by N2 glaciation, what remains a mystery is the specific nature of the glacial erosion mechanism(s) responsible for the observed features. To better resolve this puzzle, we perform landform evolution modeling of several glacial erosion processes known from terrestrial H2O ice glaciation studies. These terrestrial processes, which depend upon whether or not the glacier's base is wet or dry, include quarrying/plucking and fluvial erosion. We also consider new erosional processes (to be described in this presentation) which are unique to the highly insulating character of solid N2 including both phase change induced hydrofracture and geothermally driven basal melt. Until improvements in our knowledge of solid N2's rheology are made available (including its mechanical behavior as a binary/trinary mixture of CH4 and CO), it is difficult to assess with high precision which of the aforementioned erosion mechanisms are responsible for the observed surface etchings. Nevertheless, we consider a model crater surface and examine its erosional development due to flowing N2 glacial ice as built up over time according to N2 deposition rates based on GCM modeling of Pluto's ancient atmosphere. For given erosional mechanism our aim is to determine the permissible ranges of model input parameters (e.g., ice strength, flow rates, grain sizes, quarrying rates, etc.) that best reproduces the observed length scales found on the observed fluted craters. As of the writing of this abstract, both the processes of quarrying and phase change induced hydrofracture appear to be most promising at explaining the fluted crater ridging.

40 CFR 761.369 - Pre-cleaning the surface.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Pre-cleaning the surface. 761.369 Section 761.369 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT POLYCHLORINATED BIPHENYLS (PCBs) MANUFACTURING, PROCESSING, DISTRIBUTION IN COMMERCE, AND USE...

Element concentrations in growth rings of trees near an abandoned wood-preserving plant site at Jackson, Tennessee

USGS Publications Warehouse

Yanosky, T.M.; Carmichael, J.K.

1993-01-01

Multielement analysis was performed on individual annual rings of trees growing at and near an abandoned wood-preserving plant site in Jackson, Tennessee, that operated from the early 1930's until 1981. Numerous organic compounds associated with the wood-preserving process have been detected in soils, ground water, and surface water within much of the site. Tree-ring investigations were conducted prior to investigations of ground water downgradient from the site to determine if trees preserved an areal and temporal record of contaminant movement into offsite areas. Increment cores were collected from trees on the abandoned plant site, in downgradient areas west and south of the site, and at two locations presumably unaffected by contamination from the site. Multielement analysis by proton-induced X-ray emission was performed on 5 to 15 individual growth rings from each of 34 trees that ranged in age from about 5 to 50 years. Concentrations of 16 elements were evaluated by analyzing average concentrations within the 1987, 1989, and 1990 rings of all trees; analyzing element-concentration trends along entire core radii; and analyzing element correlations between and among trees. Concentrations of some nutrients and trace metals were elevated in the outermost sapwood rings of some trees that grow south and southwest of the most contaminated part of the site; small trees on the main part of the site and larger trees to the west generally contained fewer rings with elevated concentrations, particularly of trace metals. Concentrations of several elements elevated in tree rings also were elevated in water samples collected from the reach of a stream that flows near the southwestern part of the site. Multielement analysis of each ring of a willow growing along the southern boundary of the site detected extremely large concentrations of chromium, nickel, and iron in rings that formed in 1986 and thereafter. Relative increases in the concentrations of these elements also were detected in a silver maple growing next to the willow, but not in another silver maple growing 150 meters farther to the west. An oak growing in the southwestern part of the study area contained large concentrations of calcium and several trace elements, and some trees south of the abandoned site contained large concentrations of phosphorus or potassium. Concentrations of trace metals and nutrients in some trees may be related to wood-preserving activities at the site and possibly to remedial efforts conducted during the early to mid 1980's.However, the possibility cannot be discounted that large concentrations of some elements are from sources other than the wood-preserving facility, or in part from flooding of the South Fork Forked Deer River.

40 CFR 63.7907 - What are my inspection and monitoring requirements for surface impoundments?

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 13 2010-07-01 2010-07-01 false What are my inspection and monitoring requirements for surface impoundments? 63.7907 Section 63.7907 Protection of Environment ENVIRONMENTAL... Remediation Surface Impoundments § 63.7907 What are my inspection and monitoring requirements for surface...

40 CFR 63.7907 - What are my inspection and monitoring requirements for surface impoundments?

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 14 2013-07-01 2013-07-01 false What are my inspection and monitoring requirements for surface impoundments? 63.7907 Section 63.7907 Protection of Environment ENVIRONMENTAL... Remediation Surface Impoundments § 63.7907 What are my inspection and monitoring requirements for surface...

40 CFR 63.7907 - What are my inspection and monitoring requirements for surface impoundments?

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 14 2014-07-01 2014-07-01 false What are my inspection and monitoring requirements for surface impoundments? 63.7907 Section 63.7907 Protection of Environment ENVIRONMENTAL... Remediation Surface Impoundments § 63.7907 What are my inspection and monitoring requirements for surface...

40 CFR 63.7907 - What are my inspection and monitoring requirements for surface impoundments?

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 14 2012-07-01 2011-07-01 true What are my inspection and monitoring requirements for surface impoundments? 63.7907 Section 63.7907 Protection of Environment ENVIRONMENTAL... Remediation Surface Impoundments § 63.7907 What are my inspection and monitoring requirements for surface...

40 CFR 63.7907 - What are my inspection and monitoring requirements for surface impoundments?

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 13 2011-07-01 2011-07-01 false What are my inspection and monitoring requirements for surface impoundments? 63.7907 Section 63.7907 Protection of Environment ENVIRONMENTAL... Remediation Surface Impoundments § 63.7907 What are my inspection and monitoring requirements for surface...

Bioinspired Surface Treatments for Improved Decontamination: Commercial Products

DTIC Science & Technology

2017-07-28

simulants paraoxon, methyl salicylate, dimethyl methylphosphate, and diisopropyl fluorophosphates following treatment of contaminated surfaces with a...treatment of contaminated surfaces with a soapy water solution is reported along with droplet diffusion on the surfaces and wetting angles...Defense Program (CBDP) seeks to provide protection of forces in a contaminated environment including contamination avoidance, individual protection

Erosion protection conferred by whole human saliva, dialysed saliva, and artificial saliva

NASA Astrophysics Data System (ADS)

Baumann, T.; Kozik, J.; Lussi, A.; Carvalho, T. S.

2016-10-01

During dental erosion, tooth minerals are dissolved, leading to a softening of the surface and consequently to irreversible surface loss. Components from human saliva form a pellicle on the tooth surface, providing some protection against erosion. To assess the effect of different components and compositions of saliva on the protective potential of the pellicle against enamel erosion, we prepared four different kinds of saliva: human whole stimulated saliva (HS), artificial saliva containing only ions (AS), human saliva dialysed against artificial saliva, containing salivary proteins and ions (HS/AS), and human saliva dialysed against deionised water, containing only salivary proteins but no ions (HS/DW). Enamel specimens underwent four cycles of immersion in either HS, AS, HS/AS, HS/DW, or a humid chamber (Ctrl), followed by erosion with citric acid. During the cycling process, the surface hardness and the calcium released from the surface of the specimens were measured. The different kinds of saliva provided different levels of protection, HS/DW exhibiting significantly better protection than all the other groups (p < 0.0001). Different components of saliva, therefore, have different effects on the protective properties of the pellicle and the right proportions of these components in saliva are critical for the ability to form a protective pellicle.

Preliminary test of two stump surface protectants against Fomes annosus.

Treesearch

E.E. Nelson; C.Y. Li

1980-01-01

Two materials, monolaurin (at two concentrations) and an unidentified species of the genus Streptomyces, were tested along with borax for ability to protect freshly cut stump surfaces of western hemlock (Tsuga heterophylla (Raf.) Sarg.) from colonization by Fomes annosus. Protectants were significantly (P...

Undercutting of defects in thin film protective coatings on polymer surfaces exposed to atomic oxygen

NASA Technical Reports Server (NTRS)

Rutledge, Sharon K.; Mihelcic, Judith A.

1989-01-01

Protection for polymeric surfaces is needed to make them durable in the low Earth orbital environment, where oxidation by atomic oxygen is the predominant failure mechanism. Thin film coatings of oxides such as silicon dioxide are viable candidates to provide this protection, but concern has been voiced over the ability of these coatings to protect when defects are present in the coating due to surface anomalies occurring during the deposition process, handling, or micrometeoroid and debris bombardment in low Earth orbit. When a defected coating protecting a polymer substrate is exposed to atomic oxygen, the defect provides a pathway to the underlying polymer allowing oxidation and subsequent undercutting to occur. Defect undercutting was studied for sputter deposited coatings of silicon dioxide on polyimide Kapton. Preliminary results indicate that undercutting may be limited as long as the coating remains intact with the substrate. Therefore, coatings may not need to be defect free to give protection to the underlying surface.

Entrainment of viruses from septic tank leach fields through a shallow, sandy soil aquifer.

PubMed

Vaughn, J M; Landry, E F; Thomas, M Z

1983-05-01

A study was conducted which focused on movement of naturally occurring human enteroviruses from a subsurface wastewater disposal system through a shallow aquifer. The potential for significant entrainment of virus particles was evidenced by their recovery at down-gradient distances of 67.05 m and from aquifer depths of 18 m. A significant negative correlation was observed between virus occurrence and the distance from the "septage" (leaching pool) source. Virus occurrence could not be statistically correlated with either total or fecal coliforms, indicating the limitations of current microbial water quality indicators for predicting the virological quality of groundwater.

Capstone Report on the Application, Monitoring, and Performance of Permeable Reactive Barriers for Ground-Water Remediation: Volume 1: Performance Evaluations at Two Sites

DTIC Science & Technology

2003-08-01

sepiolite , Mg 4 (OH) 2 Si 6 O 15 ·H 2 O...EC050801-3-5 EC050801-3-3 EC050801-3-2 EC050801-3-1 In te n si ty degrees 2-theta In te n si ty In te n si ty downgradient edge upgradient edge In te n...400 b ic a rb o n a te , m g /L 0 2 4 6 8 10 12 14 16 si lic a , m g /L Figure 4.12 Average (± 1 s.d.) concentrations of Na, K , Ca,

The Role of Eddies in the General Ocean Circulation: Proceedings of ’Aha Huliko’a Hawaiian Winter Workshop Held at Manoa on January 5-7, 1983

DTIC Science & Technology

1983-01-01

January 5-7, 1983. (SOI iE): Hnai1 Int of Gtnphyqirdt Honohlul. To ORDER THE COMPLETE COMPILATION REPORT USE AD-A137 212 THE COMPONENT PART IS PROVIDED...Holland, 1979). Outside of the region of the wavemaker the vorticity-mixingtheory leads us to expect a down-gradient (southward) component of v’ q...calling them "mesoscale" begins to be marginal. The climatological T4 5 0 field used above is based on cubic spline fits to averages over 2’ (latitude) by

DOE Office of Scientific and Technical Information (OSTI.GOV)

LaFreniere, L. M.; Environmental Science Division

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

Hydrogeology and water quality of the West Valley Creek Basin, Chester County, Pennsylvania

USGS Publications Warehouse

Senior, Lisa A.; Sloto, Ronald A.; Reif, Andrew G.

1997-01-01

The West Valley Creek Basin drains 20.9 square miles in the Piedmont Physiographic Province of southeastern Pennsylvania and is partly underlain by carbonate rocks that are highly productive aquifers. The basin is undergoing rapid urbanization that includes changes in land use and increases in demand for public water supply and wastewater disposal. Ground water is the sole source of supply in the basin.West Valley Creek flows southwest in a 1.5-mile-wide valley that is underlain by folded and faulted carbonate rocks and trends east-northeast, parallel to regional geologic structures. The valley is flanked by hills underlain by quartzite and gneiss to the north and by phyllite and schist to the south. Surface water and ground water flow from the hills toward the center of the valley. Ground water in the valley flows west-southwest parallel to the course of the stream. Seepage investigations identified losing reaches in the headwaters area where streams are underlain by carbonate rocks and gaining reaches downstream. Tributaries contribute about 75 percent of streamflow. The ground-water and surface-water divides do not coincide in the carbonate valley. The ground-water divide is about 0.5 miles west of the surface-water divide at the eastern edge of the carbonate valley. Underflow to the east is about 1.1 inches per year. Quarry dewatering operations at the western edge of the valley may act partly as an artificial basin boundary, preventing underflow to the west. Water budgets for 1990, a year of normal precipitation (45.8 inches), and 1991, a year of sub-normal precipitation (41.5 inches), were calculated. Streamflow was 14.61 inches in 1990 and 12.08 inches in 1991. Evapotranspiration was estimated to range from 50 to 60 percent of precipitation. Base flow was about 62 percent of streamflow in both years. Exportation by sewer systems was about 3 inches from the basin and, at times, equaled base flow during the dry autumn of 1991. Recharge was estimated to be 18.5 inches in 1990 and 13.7 inches in 1991. Ground-water quality in the basin reflects differences in lithology and has been affected by human activities. Ground water in the carbonate rocks is naturally hard, has a near neutral pH, and contains more dissolved solids and less dissolved iron, manganese, and radon-222 than ground water in the noncarbonate rocks, which is soft, with moderately acidic to acidic pH. Regional contamination by chloride and nitrate and local contamination by organic compounds and metals was detected. Natural background concentrations are estimated to be about 1 milligram per liter for nitrate as nitrogen and less than 3 milligrams per liter for chloride. Ground water in unsewered areas and agricultural areas of the basin has median concentrations of nitrate that are greater than those in ground water from other areas; septic system effluent and fertilizer are probable sources of elevated nitrate. Water samples from wells in urbanized areas contain greater concentrations of chloride than samples from wells in residential areas; road salt is the probable source of elevated chloride. Organic solvents, especially trichloroethylene, were detected in 30 percent of the wells sampled in the urbanized carbonate valley. Most of the organic solvents and some of the metals in ground water were detected near old industrial sites.Base-flow stream quality of West Valley Creek was determined at 15 sites from monthly sampling for 1 year. Differences in stream quality reflect differences in lithology, land use, and point sources in tributary subbasins and mainstem reaches. The chemical composition of base flow in the mainstem is dominated by ground-water discharge from carbonate rocks. Elevated concentrations of nitrate (greater than 3 milligrams per liter as nitrogen) in base flow were measured in a tributary draining agricultural land and in a tributary draining an unsewered residential area. Elevated concentrations of phosphate (greater than 0.5 milligrams per liter as phosphorus) were measured in a stream that receives treated sewage effluent. Discharge of water containing elevated sulfate (about 250 milligrams per liter) from quarry dewatering operations contributes to die increase in sulfate concentration (of 10 to 40 milligrams per liter) in base flow downstream from the quarry. The chloride load at all stream sites is greater than the load contributed by precipitation and mineral weathering to the basin, indicating anthropogenic sources of chloride throughout the basin. The diversity index of the benthic invertebrate community has increased since 1973 at the longterm biological monitoring site on West Valley Creek, indicating an improvement in stream quality. The improvement probably is related to controls on discharges and banning of pesticides, such as DOT, in the 1970's. Concentrations of dissolved constituents, except for chloride, determined for base flow in the autumn do not appear to have changed since 1971. Application of the seasonal Kendall test for trend indicates that concentrations of chloride in base flow have increased since 1971; this increase may be related to the increase in urbanization in the basin. The benthic community structure at the West Valley Creek site in 1991 indicates slight nutrient enrichment.Lithium was detected in ground water and surface water downgradient from two lithiumprocessing facilities. Until 1991, lithium was discharged into a losing reach of West Valley Creek, thus introducing lithium into the ground-water system. The potential for cross-contamination between the ground-water and surface-water systems is great, as demonstrated by the detection of lithium in ground water and surface water downstream and downgradient from the two lithium-processing facilities. The lithium that was discharged into the creek acts as a conservative tracer in gaining reaches of West Valley Creek, maintaining a mass balance and characteristic isotopic signature. Lithium-7/lithium-6 ratios were greater in streams that are affected by sewage and by lithium-processing discharges and in ground water downgradient from the lithium-processing facilities than natural background lithium isotopic ratios.

Quadrant III RFI draft report: Appendix B-I, Volume 3

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1992-12-01

In order to determine the nature and extent of contamination at a RCRA site it is often necessary to investigate and characterize the chemical composition of the medium in question that represents background conditions. Background is defined as current conditions present at a site which are unaffected by past treatment, storage, or disposal of hazardous waste (OEPA, 1991). The background composition of soils at the Portsmouth Gaseous Diffusion Plant (PORTS) site was characterized for the purpose of comparing investigative soil data to a background standard for each metal on the Target Compound List/Target Analyte List and each radiological parameter ofmore » concern in this RFI. Characterization of background compositions with respect to organic parameters was not performed because the organic parameters in the TCL/TAL are not naturally occurring at the site and because the site is not located in a highly industrialized area nor downgradient from another unrelated hazardous waste site. Characterization of the background soil composition with respect to metals and radiological parameters was performed by collecting and analyzing soil boring and hand-auger samples in areas deemed unaffected by past treatment, storage, or disposal of hazardous waste. Criteria used in determining whether a soil sample location would be representative of the true background condition included: environmental history of the location, relation to Solid Waste Management Units (SWMU`s), prevailing wind direction, surface runoff direction, and ground-water flow direction.« less

Quadrant III RFI draft report: Appendix B-I, Volume 3

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1992-12-01

In order to determine the nature and extent of contamination at a RCRA site it is often necessary to investigate and characterize the chemical composition of the medium in question that represents background conditions. Background is defined as current conditions present at a site which are unaffected by past treatment, storage, or disposal of hazardous waste (OEPA, 1991). The background composition of soils at the Portsmouth Gaseous Diffusion Plant (PORTS) site was characterized for the purpose of comparing investigative soil data to a background standard for each metal on the Target Compound List/Target Analyte List and each radiological parameter ofmore » concern in this RFI. Characterization of background compositions with respect to organic parameters was not performed because the organic parameters in the TCL/TAL are not naturally occurring at the site and because the site is not located in a highly industrialized area nor downgradient from another unrelated hazardous waste site. Characterization of the background soil composition with respect to metals and radiological parameters was performed by collecting and analyzing soil boring and hand-auger samples in areas deemed unaffected by past treatment, storage, or disposal of hazardous waste. Criteria used in determining whether a soil sample location would be representative of the true background condition included: environmental history of the location, relation to Solid Waste Management Units (SWMU's), prevailing wind direction, surface runoff direction, and ground-water flow direction.« less

Assessment of intrinsic bioremediation of jet fuel contamination in a shallow aquifer, Beaufort, South Carolina

USGS Publications Warehouse

Chapelle, Frank; Landmeyer, J.E.; Bradley, P.M.

1995-01-01

Field and laboratory studies show that microorganisms indigenous to the ground-water system underlying Tank Farm C, Marine Corps Air Station Beaufort, S.C., degrade petroleum hydrocarbons under aerobic and anaerobic conditions. Under aerobic conditions, sediments from the shallow aquifer underlying the site mineralized radiolabeled (14C) toluene to 14CO2 with first-order rate constants of about -0.29 per day. Sediments incubated under anaerobic conditions mineralized radiolabeled toluene more slowly, with first-order rate constants of -0.001 per day. Although anaerobic rates of biodegradation are low, they are significant in the hydrologic and geochemical context of the site. Because of low hydraulic conductivities (1.9-9.1 feet per day) and low hydraulic gradients (about 0.004 feet per feet), ground water flows slowly (approximately 20 feet per year) at this site. Furthermore, aquifer sediments contain organic-rich peat that has a high sorptive capacity. Under these conditions, hydrocarbon contaminants have moved no further than 10 feet downgradient of the jet fuel free product. Digital solute-transport simulations, using the range of model parameters measured at the site, show that dissolved contaminants will be completely degraded before they are discharged from the aquifer into adjacent surface-water bodies. These results show that natural attenuation processes are containing the migration of soluble hydrocarbons, and that intrinsic bioremediation is a potentially effective remedial strategy at this site.

Water Quality and Geochemical Modeling of Water at an Abandoned Coal Mine Reclaimed With Coal Combustion By-Products

USGS Publications Warehouse

Haefner, Ralph J.

2002-01-01

An abandoned coal mine in eastern Ohio was reclaimed with 125 tons per acre of pressurized fluidized bed combustion (PFBC) by-product. Water quality at the site (known as the Fleming site) was monitored for 7 years after reclamation; samples included water from soil-suction lysimeters (interstitial water), wells, and spring sites established downgradient of the application area. This report presents a summary of data collected at the Fleming site during the period September 1994 through June 2001. Additionally, results of geochemical modeling are included in this report to evaluate the potential fate of elements derived from the PFBC by-product. Chemical analyses of samples of interstitial waters within the PFBC by-product application area indicated elevated levels of pH and specific conductance and elevated concentrations of boron, calcium, chloride, fluoride, magnesium, potassium, strontium, and sulfate compared to water samples collected in a control area where traditional reclamation methods were used. Magnesium-to-calcium (Mg:Ca) mole ratios and sulfur-isotope ratios were used to trace the PFBC by-product leachate and showed that little, if any, leachate reached ground water. Concentrations of most constituents in interstitial waters in the application-area decreased during the seven sampling rounds and approached background concentrations observed in the control area; however, median pH in the application area remained above 6, indicating that some acid-neutralizing capacity was still present. Although notable changes in water quality were observed in interstitial waters during the study period, quality of ground water and spring water remained poor. Water from the Fleming site was not potable, given exceedances of primary and secondary Maximum Contaminant Levels (MCLs) for inorganic constituents in drinking water set by the U.S. Environmental Protection Agency. Only fluoride and sulfate, which were found in higher concentrations in application-area interstitial waters than in control-area interstitial waters, could be related to the PFBC by-product. Concentrations of arsenic, lead, and selenium typically were at or below the detection limits (generally 1 or 2 micrograms per liter). Elements detected at elevated concentrations in PFBC by-product application-area interstitial waters were not evident in downgradient ground water or spring water. Dilution of leachate by ground water was confirmed with a mixing model generated by the computer code NETPATH. Additionally, thermodynamic modeling of the chemical composition of water samples by use of the computer code PHREEQC indicated favorable conditions for precipitation of secondary minerals in the unsaturated zone and in aquifer materials. Because of low application rates of PFBC by-product and precipitation and sorption of elements in the unsaturated zone, it is improbable that concentrations of any toxic elements of concern (arsenic, lead, or selenium) will exceed drinking-water standards at this site or other sites where similar volumes of PFBC by-products are used.

40 CFR 761.267 - Sampling non-porous surfaces.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Sampling non-porous surfaces. 761.267 Section 761.267 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES... PROHIBITIONS Cleanup Site Characterization Sampling for PCB Remediation Waste in Accordance with § 761.61(a)(2...

40 CFR 761.265 - Sampling bulk PCB remediation waste and porous surfaces.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Sampling bulk PCB remediation waste and porous surfaces. 761.265 Section 761.265 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY..., DISTRIBUTION IN COMMERCE, AND USE PROHIBITIONS Cleanup Site Characterization Sampling for PCB Remediation Waste...

40 CFR 761.267 - Sampling non-porous surfaces.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Sampling non-porous surfaces. 761.267 Section 761.267 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES... PROHIBITIONS Cleanup Site Characterization Sampling for PCB Remediation Waste in Accordance with § 761.61(a)(2...

40 CFR 761.265 - Sampling bulk PCB remediation waste and porous surfaces.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Sampling bulk PCB remediation waste and porous surfaces. 761.265 Section 761.265 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY..., DISTRIBUTION IN COMMERCE, AND USE PROHIBITIONS Cleanup Site Characterization Sampling for PCB Remediation Waste...

40 CFR 761.267 - Sampling non-porous surfaces.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Sampling non-porous surfaces. 761.267 Section 761.267 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES... PROHIBITIONS Cleanup Site Characterization Sampling for PCB Remediation Waste in Accordance with § 761.61(a)(2...

40 CFR 761.265 - Sampling bulk PCB remediation waste and porous surfaces.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Sampling bulk PCB remediation waste and porous surfaces. 761.265 Section 761.265 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY..., DISTRIBUTION IN COMMERCE, AND USE PROHIBITIONS Cleanup Site Characterization Sampling for PCB Remediation Waste...

40 CFR 761.265 - Sampling bulk PCB remediation waste and porous surfaces.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Sampling bulk PCB remediation waste and porous surfaces. 761.265 Section 761.265 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY..., DISTRIBUTION IN COMMERCE, AND USE PROHIBITIONS Cleanup Site Characterization Sampling for PCB Remediation Waste...

Topological semimetals with Riemann surface states

NASA Astrophysics Data System (ADS)

Fang, Chen; Lu, Ling; Liu, Junwei; Fu, Liang

Topological semimetals have robust bulk band crossings between the conduction and the valence bands. Among them, Weyl semimetals are so far the only class having topologically protected signatures on the surface known as the ``Fermi arcs''. Here we theoretically find new classes of topological semimetals protected by nonsymmorphic glide reflection symmetries. On a symmetric surface, there are multiple Fermi arcs protected by nontrivial Z2 spectral flows between two high-symmetry lines (or two segments of one line) in the surface Brillouin zone. We observe that so far topological semimetals with protected Fermi arcs have surface dispersions that can be mapped to noncompact Riemann surfaces representing simple holomorphic functions. We propose perovskite superlattice [(SrIrO3)2m, (CaIrO3)2n] as a nonsymmorphic Dirac semimetal. C.F. and L.F. were supported by the S3TEC Solid State Solar Thermal Energy Conversion Center, an Energy Frontier Research Center funded by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences (BES), under Award No. DE-SC0001299/DE.

Protection of lithographic components from particle contamination

DOEpatents

Klebanoff, Leonard E.; Rader, Daniel J.

2000-01-01

A system that employs thermophoresis to protect lithographic surfaces from particle deposition and operates in an environment where the pressure is substantially constant and can be sub-atmospheric. The system (thermophoretic pellicle) comprises an enclosure that surrounds a lithographic component whose surface is being protected from particle deposition. The enclosure is provided with means for introducing a flow of gas into the chamber and at least one aperture that provides for access to the lithographic surface for the entry and exit of a beam of radiation, for example, and further controls gas flow into a surrounding low pressure environment such that a higher pressure is maintained within the enclosure and over the surface being protected. The lithographic component can be heated or, alternatively the walls of the enclosure can be cooled to establish a temperature gradient between the surface of the lithographic component and the walls of the enclosure, thereby enabling the thermophoretic force that resists particle deposition.

Method for protection of lithographic components from particle contamination

DOEpatents

Klebanoff, Leonard E.; Rader, Daniel J.

2001-07-03

A system that employs thermophoresis to protect lithographic surfaces from particle deposition and operates in an environment where the pressure is substantially constant and can be sub-atmospheric. The system (thermophoretic pellicle) comprises an enclosure that surrounds a lithographic component whose surface is being protected from particle deposition. The enclosure is provided with means for introducing a flow of gas into the chamber and at least one aperture that provides for access to the lithographic surface for the entry and exit of a beam of radiation, for example, and further controls gas flow into a surrounding low pressure environment such that a higher pressure is maintained within the enclosure and over the surface being protected. The lithographic component can be heated or, alternatively the walls of the enclosure can be cooled to establish a temperature gradient between the surface of the lithographic component and the walls of the enclosure, thereby enabling the thermophoretic force that resists particle deposition.

Radium mobility and the age of groundwater in public-drinking-water supplies from the Cambrian-Ordovician aquifer system, north-central USA

USGS Publications Warehouse

Stackelberg, Paul E.; Szabo, Zoltan; Jurgens, Bryant C.

2018-01-01

High radium (Ra) concentrations in potable portions of the Cambrian-Ordovician (C-O) aquifer system were investigated using water-quality data and environmental tracers (3H, 3Hetrit, SF6, 14C and 4Herad) of groundwater age from 80 public-supply wells (PSWs). Groundwater ages were estimated by calibration of tracers to lumped parameter models and ranged from modern (<50 yr) in upgradient, regionally unconfined areas to ancient (>1 Myr) in the most downgradient, confined portions of the potable system. More than 80 and 40 percent of mean groundwater ages were older than 1000 and 50,000 yr, respectively. Anoxic, Fe-reducing conditions and increased mineralization develop with time in the aquifer system and mobilize Ra into solution resulting in the frequent occurrence of combined Ra (Rac = 226Ra + 228Ra) at concentrations exceeding the USEPA MCL of 185 mBq/L (5 pCi/L). The distribution of the three Ra isotopes comprising total Ra (Rat = 224Ra + 226Ra + 228Ra) differed across the aquifer system. The concentrations of 224Ra and 228Ra were strongly correlated and comprised a larger proportion of the Rat concentration in samples from the regionally unconfined area, where arkosic sandstones provide an enhanced source for progeny from the 232Th decay series. 226Ra comprised a larger proportion of the Ratconcentration in samples from downgradient confined regions. Concentrations of Rat were significantly greater in samples from the regionally confined area of the aquifer system because of the increase in 226Ra concentrations there as compared to the regionally unconfined area. 226Ra distribution coefficients decreased substantially with anoxic conditions and increasing ionic strength of groundwater (mineralization), indicating that Ra is mobilized to solution from solid phases of the aquifer as adsorption capacity is diminished. The amount of 226Ra released from solid phases by alpha-recoil mechanisms and retained in solution increases relative to the amount of Ra sequestered by adsorption processes or co-precipitation with barite as adsorption capacity and the concentration of Ba decreases. Although 226Ra occurred at concentrations greater than 224Ra or 228Ra, the ingestion exposure risk was greater for 228Ra owing to its greater toxicity. In addition, 224Ra added substantial alpha-particle radioactivity to potable samples from the C-O aquifer system. Thus, monitoring for Ra isotopes and gross-alpha-activity (GAA) is important in upgradient, regionally unconfined areas as downgradient, and GAA measurements made within 72 h of sample collection would best capture alpha-particle radiation from the short-lived 224Ra.

Effects of dried wastewater-treatment sludge application on ground-water quality in South Dade County, Florida

USGS Publications Warehouse

Howie, Barbara

1992-01-01

Four test fields in the south Dade agricultural area were studied to determine the effects of sludge application on ground-water quality. Two fields had been cultivated for 10 years or more, and two had not been farmed for at least 10 years. The fields were representative of the area's two soil types (Rockdale and Perrine marl) and two major crop types (row crops and groves). Before the application of sludge, wells upgradient of, within, and downgradient of each field were sampled for possible sludge contaminants at the end of wet and dry seasons. Municipal wastewater treatment sludge from the Dade County Water and Sewe Authority Department was then applied to the fields at varying application rates. The wells at each field were sampled over a 2-year period under different hydrologic conditions for possible sludge-related constituents (specific conductance, pH, alkalinity, nitrogen, phosphorus, total organic carbon, copper, iron, magnesium, manganese, potassium, zinc, arsenic, cadmium, chloride, chromium, lead, mercury, nickel, and sodium). Comparisons were made between water quality in the vicinity of the test fields and Florida Department of Environmental Regulation primary and secondary drinking-water regulations, an between water quality upgradient of, beneath, and downgradient of the fields. Comparisons between presludge and postsludge water quality did not indicate any improvement because of retention of agrichemicals by the sludge nor did they indicate any deterioration because of leaching from the sludge. Comparisons of water quality upgradient of the fields to water quality beneath and downgradient of the fields also did not indicate any changes related to sludge. Florida Department of Environmental Regulation primary and secondary drinking-water regulations wer exceeded at the Rockdale maximum-application field by mercury (9.5 ug/L (micrograms per liter)), and the Perrine marl maximum-application field by manganese (60 ug/L) and lead (85 ug/L), and at the Perrine marl row-crop field by mercury (5.2 ug/L). All other exceedances were either in presludge or upgradient samples, or they were for constituents or properties, such as iron and color, which typically exceed standards in native ground water. Acid-extractable and base-neutral compounds, volatile organic compounds, chlorophenoxy herbicides, organophosphorus insecticides, and organochlorine compounds were analyzed for one shallow well at each field twice annually. Those compounds that equaled or exceeded the detection limit after sludge was applied included benzene (0.3 and 1.2 ug/L), chloroform (0.2 and 0.3 ug/L), bis(2-Ethylhexyl)phthalate (29 and 42 ug/L), methylene chloride (14 ug/L), tolulene (0.2, 0.4, 0.5, 1.3, and 4.4 ug/L), 1, 1,1-trichloroethana (0.6 ug/L), trichloroethylene (0.3 ug/L), 2.4-D (0.01 ug/L), and xylene (0.3 ug/L). It ws not possible to ascertain the origin of these compounds becuase they are available from sources other than sludge.

Iron deposition as acidic groundwater encounters carbonates in the alluvium of Pinal Creek, Arizona, U.S.A.

USGS Publications Warehouse

Lind, Carol J.; Oscarson, R.L.

1997-01-01

In a column experiment, acidic groundwater from Pinal Creek Arizona, a Cu mining area, was eluted through a composited alluvial sample obtained from a core that had been removed from a well downgradient of the acidic groundwater. The minerals present in typical grains and flakes in the alluvium before and after the elution were determined by X-ray diffraction (XRD), scanning electron microscopy, and energy dispersive multichannel analyses (EDX). The concentrations of Fe, Ti, Mn, Si, Al, Na, Ca, K, Mg and S in these grains and flakes and in their microcrystalline surface coatings were measured by EDX. In addition to magnetite, hematite, and Fe-Ti oxides, Fe was most concentrated in micas (especially biotite-like flakes) and in the microcrystalline coatings. The measured elements in these microcrystalline coatings were primarily K, Fe, Al, and Si. The microcrystalline coatings on the mica flakes also contained Mg. The approximate 1:3 Mg:Si atomic ratios (ARs) of the biotite-like flakes both before and after the elution would suggest that the Fe deposited during the elution had not substituted for Mg in these flakes. As a result of the elution, assuming no loss of Si, the averaged recorded Fe:Si AR of the microcrystalline coatings increased from (0,46 to 0.58):3.00. Iron deposition on the typical grains and flakes may relate to the presence of Fe in the particle on which it is deposited or to the presence of Fe in the microcrystalline surface coatings before elution. The data here are not sufficient for a statistical evaluation, but elution caused the following trends: (1) The Fe:Si A R increased in the (K,Fe,Al,Si)-microcrystalline surface coatings; (2) For the mica flakes, there was more than a 2-fold increase in the Fe:Si AR for the microcrystalline surface coatings of the Fe-rich biotite-like flakes but no measurable increase of the Fe:Si AR for the microcrystalline surface coatings of the muscovite-like flakes that contained 3-5 times less Fe; (3) Also for the biotite-like flakes, the increase in Fe:Si AR was greater in the flakes that had a higher Fe:Si AR; (4) The Fe deposition on the Fe-rich microcrystalline surface coatings of the feldspar was much greater than on the Fe-poor, beige quartz and feldspar grains that, prior to elution, had only CaSO4 microcrystalline coatings; and (5) No Fe was deposited on Fe-poor grains with no microcrystalline surface coating.

Demineralization of resin-sealed enamel by soft drinks in a clinically relevant pH cycling model.

PubMed

Bartels, Agata A; Evans, Carla A; Viana, Grace; Bedran-Russo, Ana K

2016-04-01

To compare the in vitro protective effect of orthodontic sealants on the enamel demineralization under a soft drink-induced erosive challenge. The facial surfaces of bovine incisors were sectioned into 5 mm x 4 mm x 4 mm enamel blocks. Specimens were randomly assigned to three surface protection measures: control (exposed enamel), coating with Transbond XT (unfilled resin primer), or coating with Opal Seal (filled and fluoride releasing primer). Thermocycling was used to simulate aging. The specimens were pH cycled through an acidic buffer, test beverage and a neutral buffer for a total of 7 days. Test beverages included water, Diet Mountain Dew, and Coke Classic. Quantitative light-induced fluorescence (QLF) images were taken at baseline and after aging. Final QLF images were taken to evaluate the demineralization of enamel. Data were analyzed statistically using a two-way ANOVA to compare the interaction between enamel surface protection and beverages as well as one-way ANOVA to compare surface protection and the test beverage levels. A statistically significant interaction was found between the surface protected groups and the test beverage groups (P < 0.05). Statistically significant differences were found among the test beverage groups (P < 0.05) and among the surface protection groups (P < 0.05). Coke Classic went through the sealant layer resulting in high enamel demineralization. Enamel coating with Opal Seal significantly reduced the erosive attack of beverages.

MER Surface Phase; Blurring the Line Between Fault Protection and What is Supposed to Happen

NASA Technical Reports Server (NTRS)

Reeves, Glenn E.

2008-01-01

An assessment on the limitations of communication with MER rovers and how such constraints drove the system design, flight software and fault protection architecture, blurring the line between traditional fault protection and expected nominal behavior, and requiring the most novel autonomous and semi-autonomous elements of the vehicle software including communication, surface mobility, attitude knowledge acquisition, fault protection, and the activity arbitration service.

40 CFR 721.91 - Computation of estimated surface water concentrations: Instructions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Computation of estimated surface water concentrations: Instructions. 721.91 Section 721.91 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Certain Significant New Uses § 721.91 Computation of...

40 CFR 721.91 - Computation of estimated surface water concentrations: Instructions.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Computation of estimated surface water concentrations: Instructions. 721.91 Section 721.91 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Certain Significant New Uses § 721.91 Computation of...

METHOD OF FORMING A PROTECTIVE COATING ON FERROUS METAL SURFACES

DOEpatents

Schweitzer, D.G.; Weeks, J.R.; Kammerer, O.F.; Gurinsky, D.H.

1960-02-23

A method is described of protecting ferrous metal surfaces from corrosive attack by liquid metals, such as liquid bismuth or lead-bismuth alloys. The nitrogen content of the ferrous metal surface is first reduced by reacting the metal surface with a metal which forms a stable nitride. Thereafter, the surface is contacted with liquid metal containing at least 2 ppm zirconium at a temperature in the range of 550 to 1100 deg C to form an adherent zirconium carbide layer on the ferrous surface.

Metal Surface Modification for Obtaining Nano- and Sub-Nanostructured Protective Layers.

PubMed

Ledovskykh, Volodymyr; Vyshnevska, Yuliya; Brazhnyk, Igor; Levchenko, Sergiy

2017-12-01

Regularities of the phase protective layer formation in multicomponent systems involving inhibitors with different mechanism of protective action have been investigated. It was shown that optimization of the composition of the inhibition mixture allows to obtain higher protective efficiency owing to improved microstructure of the phase layer. It was found that mechanism of the film formation in the presence of NaNO 2 -PHMG is due to deposition of slightly soluble PHMG-Fe complexes on the metal surface. On the basis of the proposed mechanism, the advanced surface engineering methods for obtaining nanoscaled and sub-nanostructured functional coatings may be developed.

Metal Surface Modification for Obtaining Nano- and Sub-Nanostructured Protective Layers

NASA Astrophysics Data System (ADS)

Ledovskykh, Volodymyr; Vyshnevska, Yuliya; Brazhnyk, Igor; Levchenko, Sergiy

2017-03-01

Regularities of the phase protective layer formation in multicomponent systems involving inhibitors with different mechanism of protective action have been investigated. It was shown that optimization of the composition of the inhibition mixture allows to obtain higher protective efficiency owing to improved microstructure of the phase layer. It was found that mechanism of the film formation in the presence of NaNO2-PHMG is due to deposition of slightly soluble PHMG-Fe complexes on the metal surface. On the basis of the proposed mechanism, the advanced surface engineering methods for obtaining nanoscaled and sub-nanostructured functional coatings may be developed.

Design of a Thermal and Micrometeorite Protection System for an Unmanned Lunar Cargo Lander

NASA Technical Reports Server (NTRS)

Hernandez, Carlos A.; Sunder, Sankar; Vestgaard, Baard

1989-01-01

The first vehicles to land on the lunar surface during the establishment phase of a lunar base will be unmanned lunar cargo landers. These landers will need to be protected against the hostile lunar environment for six to twelve months until the next manned mission arrives. The lunar environment is characterized by large temperature changes and periodic micrometeorite impacts. An automatically deployable and reconfigurable thermal and micrometeorite protection system was designed for an unmanned lunar cargo lander. The protection system is a lightweight multilayered material consisting of alternating layers of thermal and micrometeorite protection material. The protection system is packaged and stored above the lander common module. After landing, the system is deployed to cover the lander using a system of inflatable struts that are inflated using residual fuel (liquid oxygen) from the fuel tanks. Once the lander is unloaded and the protection system is no longer needed, the protection system is reconfigured as a regolith support blanket for the purpose of burying and protecting the common module, or as a lunar surface garage that can be used to sort and store lunar surface vehicles and equipment. A model showing deployment and reconfiguration of the protection system was also constructed.

Functions of ocular surface mucins in health and disease

PubMed Central

Mantelli, Flavio; Argüeso, Pablo

2009-01-01

Purpose of review The purpose of the present review is to describe new concepts on the role of mucins in the protection of corneal and conjunctival epithelia and to identify alterations of mucins in ocular surface diseases. Recent findings New evidence indicates that gel-forming and cell surface-associated mucins contribute differently to the protection of the ocular surface against allergens, pathogens, extracellular molecules, abrasive stress, and drying. Summary Mucins are high molecular weight glycoproteins characterized by their extensive O-glycosylation. Major mucins expressed by the ocular surface epithelia include cell surface-associated mucins MUC1, -4 and -16, and the gel-forming mucin MUC5AC. Recent advances using functional assays have allowed the examination of their roles in the protection of corneal and conjunctival epithelia. Alterations in mucin and mucin O-glycan biosynthesis in ocular surface disorders, including allergy, non-autoimmune dry eye, autoimmune dry eye, and infection, are presented. PMID:18769205

Apparatus and method for the electrolytic production of metals

DOEpatents

Sadoway, Donald R.

1991-01-01

Improved electrolytic cells and methods for producing metals by electrolytic reduction of a compound dissolved in a molten electrolyte are disclosed. In the improved cells and methods, a protective surface layer is formed upon at least one electrode in the electrolytic reduction cell and, optionally, upon the lining of the cell. This protective surface layer comprises a material that, at the operating conditions of the cell: (a) is not substantially reduced by the metal product; (b) is not substantially reactive with the cell electrolyte to form materials that are reactive with the metal product; and, (c) has an electrochemical potential that is more electronegative than that of the compound undergoing electrolysis to produce the metal product of the cell. The protective surface layer can be formed upon an electrode metal layer comprising a material, the oxide of which also satisfies the protective layer selection criteria. The protective layer material can also be used on the surface of a cell lining.

Thermal and aerothermal performance of a titanium multiwall thermal protection system

NASA Technical Reports Server (NTRS)

Avery, D. E.; Shideler, J. L.; Stuckey, R. N.

1981-01-01

A metallic thermal protection system (TPS) concept the multiwall designed for temperature and pressure at Shuttle body point 3140 where the maximum surface temperature is approximately 811 K was tested to evaluate thermal performance and structural integrity. A two tile model of titanium multiwall and a model consisting of a low temperature reusable surface insulation (LRSI) tiles were exposed to 25 simulated thermal and pressure Shuttle entry missions. The two systems performed the same, and neither system deteriorated during the tests. It is indicated that redesign of the multiwall tiles reduces tile thickness and/or weight. A nine tile model of titanium multiwal was tested for radiant heating and aerothermodynamics. Minor design changes that improve structural integrity without having a significant impact on the thermal protection ability of the titanium multiwall TPS are identified. The capability of a titanium multiwall thermal protection system to protect an aluminum surface during a Shuttle type entry trajectory at locations on the vehicle where the maximum surface temperature is below 811 K is demonstrated.

Improved performance of protected catecholic polysiloxanes for bio-inspired wet adhesion to surface oxides

PubMed Central

Heo, Jinhwa; Kang, Taegon; Jang, Se Gyu; Hwang, Dong Soo; Spruell, Jason M.; Killops, Kato L.; Waite, J. Herbert; Hawker, Craig J.

2012-01-01

A facile synthetic strategy for introducing catecholic moieties into polymeric materials based on a readily available precursor – eugenol – and efficient chemistries – tris(pentafluorophenyl)borane catalyzed silation and thiol-ene coupling is reported. Silyl-protection is shown to be critical for the oxidative stability of catecholic moieties during synthesis and processing which allows functionalized polysiloxane derivatives to be fabricated into 3-D microstructures as well as 2-D patterned surfaces. Deprotection gives stable catechol surfaces with adhesion to a variety of oxide surfaces being precisely tuned by the level of catechol incorporation. The advantage of silyl-protection for catechol functionalized polysiloxanes is demonstrated and represents a promising and versatile new platform for underwater surface treatments. PMID:23181614

Surface protected lithium-metal-oxide electrodes

DOEpatents

Thackeray, Michael M.; Kang, Sun-Ho

2016-04-05

A lithium-metal-oxide positive electrode having a layered or spinel structure for a non-aqueous lithium electrochemical cell and battery is disclosed comprising electrode particles that are protected at the surface from undesirable effects, such as electrolyte oxidation, oxygen loss or dissolution by one or more lithium-metal-polyanionic compounds, such as a lithium-metal-phosphate or a lithium-metal-silicate material that can act as a solid electrolyte at or above the operating potential of the lithium-metal-oxide electrode. The surface protection significantly enhances the surface stability, rate capability and cycling stability of the lithium-metal-oxide electrodes, particularly when charged to high potentials.

Bondable Stainless Surface Coats Protect Against Rust

NASA Technical Reports Server (NTRS)

Davis, G. D.; Shaffer, D. K.; Clearfield, H. M.; Nagle, D.; Groff, G.

1995-01-01

Report describes tests conducted to assess use of bondable stainless surface (BOSS) coating materials to protect steel cases of solid-fuel rocket motors against corrosion and to provide surface microstructure and chemistry suitable for bonding to insulating material. Eliminates need to cover cases with grease to prevent corrosion and degreasing immediately prior to use.

Superfund Record of Decision (EPA Region 4): Milan Army Ammunition Plant, TN. (First remedial action), September 1992. Interim report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1992-09-30

The 22,436-acre Milan Army Ammunition Plant (MAAP) is located in western Tennessee, 5 miles east of Milan, Tennessee. The facility was constructed in 1941 to produce and store fuses, boosters, and small- and large-caliber ammunition. The ROD addresses an interim remedy for the contaminated ground water beneath and immediately downgradient from the former ponds as OU1. The primary contaminants of concern affecting the ground water are VOCs, including carbon disulfide; other organics, including HMX, RDX, 2,4,6-TNT, 2,4-DNT, 2,6-DNT, 1,3-DNB, 1,3,5-trinitrobenzene, and nitrobenzene; and inorganics, including nitrate.

Numerical simulation of ground-water flow in La Crosse County, Wisconsin, and into nearby pools of the Mississippi River

USGS Publications Warehouse

Hunt, Randall J.; Saad, David A.; Chapel, Dawn M.

2003-01-01

The models provide estimates of the locations and amount of ground-water flow into Pool 8 and the southern portion of Pool 7 of the Mississippi River. Ground-water discharges into all areas of the pools, except along the eastern shore in the vicinity of the city of La Crosse and immediately downgradient from lock and dam 7 and 8. Ground-water flow into the pools is generally greatest around the perimeter with decreasing amounts away from the perimeter. An area of relatively high ground-water discharge extends out towards the center of Pool 7 from the upper reaches of the pool and may

Multisensor system for the protection of critical infrastructure of a seaport

NASA Astrophysics Data System (ADS)

Kastek, Mariusz; Dulski, Rafał; Zyczkowski, Marek; Szustakowski, Mieczysław; Trzaskawka, Piotr; Ciurapinski, Wiesław; Grelowska, Grazyna; Gloza, Ignacy; Milewski, Stanislaw; Listewnik, Karol

2012-06-01

There are many separated infrastructural objects within a harbor area that may be considered "critical", such as gas and oil terminals or anchored naval vessels. Those objects require special protection, including security systems capable of monitoring both surface and underwater areas, because an intrusion into the protected area may be attempted using small surface vehicles (boats, kayaks, rafts, floating devices with weapons and explosives) as well as underwater ones (manned or unmanned submarines, scuba divers). The paper will present the concept of multisensor security system for a harbor protection, capable of complex monitoring of selected critical objects within the protected area. The proposed system consists of a command centre and several different sensors deployed in key areas, providing effective protection from land and sea, with special attention focused on the monitoring of underwater zone. The initial project of such systems will be presented, its configuration and initial tests of the selected components. The protection of surface area is based on medium-range radar and LLTV and infrared cameras. Underwater zone will be monitored by a sonar and acoustic and magnetic barriers, connected into an integrated monitoring system. Theoretical analyses concerning the detection of fast, small surface objects (such as RIB boats) by a camera system and real test results in various weather conditions will also be presented.

75 FR 34666 - Stream Protection Rule; Environmental Impact Statement

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-18

... DEPARTMENT OF THE INTERIOR Office of Surface Mining Reclamation and Enforcement 30 CFR Chapter VII RIN 1029-AC63 Stream Protection Rule; Environmental Impact Statement AGENCY: Office of Surface Mining... impact statement. [[Page 34667

Structural Assessment of Tungsten-Epoxy Bonding in Spacecraft Composite Enclosures with Enhanced Radiation Protection

NASA Astrophysics Data System (ADS)

Kanerva, M.; Koerselman, J. R.; Revitzer, H.; Johansson, L.-S.; Sarlin, E.; Rautiainen, A.; Brander, T.; Saarela, O.

2014-06-01

Spacecraft include sensitive electronics that must be protected against radiation from the space environment. Hybrid laminates consisting of tungsten layers and carbon- fibre-reinforced epoxy composite are a potential solution for lightweight, efficient, and protective enclosure material. Here, we analysed six different surface treatments for tungsten foils in terms of the resulting surface tension components, composition, and bonding strength with epoxy. A hydrofluoric-nitric-sulfuric-acid method and a diamond-like carbon-based DIARC® coating were found the most potential surface treatments for tungsten foils in this study.

Electrode structure and method for making the same

DOEpatents

Affinito, John D.; Lowe, Gregory K.

2015-05-26

Electrode structures, and more specifically, electrode structures for use in electrochemical cells, are provided. The electrode structures described herein may include one or more protective layers. In one set of embodiments, a protective layer may be formed by exposing a lithium metal surface to a plasma comprising ions of a gas to form a ceramic layer on top of the lithium metal. The ceramic layer may be highly conductive to lithium ions and may protect the underlying lithium metal surface from reaction with components in the electrolyte. In some cases, the ions may be nitrogen ions and a lithium nitride layer may be formed on the lithium metal surface. In other embodiments, the protective layer may be formed by converting lithium to lithium nitride at high pressures. Other methods for forming protective layers are also provided.

Refractory thermal insulation for smooth metal surfaces

NASA Technical Reports Server (NTRS)

1964-01-01

To protect rocket metal surfaces from engine exhaust heat, a refractory thermal insulation mixture, which adheres to smooth metals, has been developed. Insulation protection over a wide temperature range can be controlled by thickness of the applied mixture.

"Electroless" E-Coating for Magnesium Alloys

NASA Astrophysics Data System (ADS)

Song, Guang-Ling

By utilizing the unique electrochemistry of Mg, a thin organic film can rapidly be deposited on the surface of a Mg alloy by dipping the Mg alloy in a cathodic E-coating bath solution without applying a current or potential. The self-deposited coating is selectively formed on Mg alloy surfaces. Although the "electroless" E-coating pre-film is relatively thin, it can offer sufficient corrosion protection for Mg alloys in a chloride-containing environment. The stability of the film can be significantly improved after curing. The corrosion resistance of the substrate Mg alloy has an important effect on the corrosion protection performance of the coating. The coating is more protective on a corrosion resistant Mg alloy than on a non-corrosion resistant Mg substrate. The coating protection performance is also influenced by the substrate surface condition or pre-treatment process. Wet cleaning + heat-treatment may be a cost-effective surface preparation/treatment for the "electroless" E-coating in industrial applications.

Surface protection coating material for controlling the decay of major construction stone

NASA Astrophysics Data System (ADS)

Arun, T.; Ray, D. K.; Gupta, V. P.; Panda, S. S.; Sahoo, P. K.; Ghosh, Jaydip; Sengupta, Pranesh; Satyam, P. V.

2017-05-01

Degradation of the building stones are creating instability in the old building and monuments which is to be protected. To investigate the characteristics of such a stones used for the construction in eastern India, we have collected the khondalite stones. The microstructural and elemental composition analysis of the khondalite stones are analyzed by using SEM, EDX and PIXE trace elemental analysis. We have prepared surface protection coating material with graphene oxide and cobalt ferrite as a base material along with other residuals. The prepared coating materials is coated on the galvanized iron substrate for further characterization. The surface morphology characteristics of the coating material is analyzed by SEM and AFM. The corrosion resistance characteristics of the prepared coating material is studied by the electrochemical impedance spectroscopy. The results suggests that the prepared coating material can be used as a surface protection materials to control the self-destruction of khondalite stones.

Portable flooring protects finished surfaces, is easily moved

NASA Technical Reports Server (NTRS)

Carmody, R. J.

1964-01-01

To protect curved, finished surface and provide support for workmen, portable flooring has been made from rigid plastic foam blocks, faced with aluminum strips. Held together by nylon webbing, the flooring can be rolled up for easy carrying.

Durability Issues for the Protection of Materials from Atomic Oxygen Attack in Low Earth Orbit

NASA Technical Reports Server (NTRS)

Banks, Bruce; Lenczewski, Mary; Demko, Rikako

2002-01-01

Low Earth orbital atomic oxygen is capable of eroding most polymeric materials typically used on spacecraft. Solar array blankets, thermal control polymers, and carbon fiber matrix composites are readily oxidized to become thinner and less capable of supporting the loads imposed upon them. Protective coatings have been developed that are durable to atomic oxygen to prevent oxidative erosion of the underlying polymers. However, the details of the surface roughness, coating defect density, and coating configuration can play a significant role as to whether or not the coating provides long duration atomic oxygen protection. Identical coatings on different surface roughness surfaces can have drastically different durability results. Examples and analysis of the causes of resultant differences in atomic oxygen protection are presented. Implications based on in-space experiences, ground laboratory testing, and computational modeling indicate that thin film vacuum-deposited aluminum protective coatings offer much less atomic oxygen protection than sputter-deposited silicon dioxide coatings.

Insect contamination protection for laminar flow surfaces

NASA Technical Reports Server (NTRS)

Croom, Cynthia C.; Holmes, Bruce J.

1986-01-01

The ability of modern aircraft surfaces to achieve laminar flow was well-accepted in recent years. Obtaining the maximum benefit of laminar flow for aircraft drag reduction requires maintaining minimum leading-edge contamination. Previously proposed insect contamination prevention methods have proved impractical due to cost, weight, or inconvenience. Past work has shown that insects will not adhere to water-wetted surfaces, but the large volumes of water required for protection rendered such a system impractical. The results of a flight experiment conducted by NASA to evaluate the performance of a porous leading-edge fluid discharge ice protection system operated as an insect contamination protections system are presented. In addition, these flights explored the environmental and atmospheric conditions most suitable for insect accumulation.

Fast Three-Dimensional Method of Modeling Atomic Oxygen Undercutting of Protected Polymers

NASA Technical Reports Server (NTRS)

Snyder, Aaron; Banks, Bruce A.

2002-01-01

A method is presented to model atomic oxygen erosion of protected polymers in low Earth orbit (LEO). Undercutting of protected polymers by atomic oxygen occurs in LEO due to the presence of scratch, crack or pin-window defects in the protective coatings. As a means of providing a better understanding of undercutting processes, a fast method of modeling atomic-oxygen undercutting of protected polymers has been developed. Current simulation methods often rely on computationally expensive ray-tracing procedures to track the surface-to-surface movement of individual "atoms." The method introduced in this paper replaces slow individual particle approaches by substituting a model that utilizes both a geometric configuration-factor technique, which governs the diffuse transport of atoms between surfaces, and an efficient telescoping series algorithm, which rapidly integrates the cumulative effects stemming from the numerous atomic oxygen events occurring at the surfaces of an undercut cavity. This new method facilitates the systematic study of three-dimensional undercutting by allowing rapid simulations to be made over a wide range of erosion parameters.

Influence of microclimate on the sustainability and reliability of weathering steel bridge

NASA Astrophysics Data System (ADS)

Kubzova, M.; Krivy, V.; Kreislova, K.

2018-04-01

Reliability and sustainability of bridge structures designed from weathering steel are influenced by the development of a sufficiently protective layer of corrosion products on its surface. The development of this protective layer is affected by several parameters such as air pollution around the bridge structure, the microclimate under the bridge, the location of surface within the bridge structure and the time of wetness. Design of structural details also significantly influences the development of the protective corrosion layer. The article deals with the results of the experimental tests carried out on the road bridge located in the city of Ostrava in the Czech Republic. The development of the protective corrosion layer on the surface of the bridge is significantly influenced by the intensive traffic under the bridge construction and the design solution of the bridge itself. Attention is focused mainly on the influence of chloride deposition on the protective function of the corrosion layer. Corrosion samples were placed on the bridge to evaluate the influence of the above-mentioned parameters. The deposition rate of chlorides spreading from the road to surfaces of the steel structure is also measured.

Ordinary People and Extra-Ordinary Protections: A Post-Kleinian Approach to the Treatment of Primitive Mental States. The New Library of Psychoanalysis 40.

ERIC Educational Resources Information Center

Mitrani, Judith L.

Many people come to analysis appearing quite ordinary on the surface. However, once below that surface, there often appear extraordinary protections created to keep at bay any awareness of deeply traumatic happenings occurring at some point in life. This book investigates the development and function of these protections, allowing the reader to…

Hydraulic and geochemical performance of a permeable reactive barrier containing zero-valent iron, Denver Federal Center

USGS Publications Warehouse

McMahon, P.B.; Dennehy, K.F.; Sandstrom, M.W.

1999-01-01

The hydraulic and geochemical performance of a 366 m long permeable reactive barrier (PRB) at the Denver Federal Center; Denver, Colorado, was evaluated. The funnel and gate system, which was installed in 1996 to intercept and remediate ground water contaminated with chlorinated aliphatic hydrocarbons (CAHs), contained four 12.2 m wide gates filled with zero-valent iron. Ground water mounding on the upgradient side of the PRB resulted in a tenfold increase in the hydraulic gradient and ground water velocity through the gates compared to areas of the aquifer unaffected by the PRB. Water balance calculations for April 1997 indicate that about 75% of the ground water moving toward the PRB from upgradient areas moved through the gates. The rest of the water either accumulated on the upgradient side of the PRB or bypassed the PRB. Chemical data from monitoring wells screened down-gradient, beneath, and at the ends of the PRB indicate that contaminants had not bypassed the PRB, except in a few isolated areas. Greater than 99% of the CAH mass entering the gates was retained by the iron. Fifty-one percent of the CAH carbon entering one gate was accounted for in dissolved C1 and C2 hydrocarbons, primarily ethane and ethene, which indicates that CAHs may adsorb to the iron prior to being dehalogenated. Treated water exiting the gates displaced contaminated ground water at a distance of at least 3 m downgradient from the PRB by the end of 1997. Measurements of dissolved inorganic ions in one gate indicate that calcite and siderite precipitation in the gate could reduce gate porosity by about 0.35% per year. Results from this study indicate that funnel and gate systems containing zero-valent iron can effectively treat ground water contaminated with CAHs. However, the hydrologic impacts of the PRB on the flow system need to be fully understood to prevent contaminants from bypassing the PRB.

Ground-water quality near an inactive landfill and sludge-spreading area, Tallahassee, Florida

USGS Publications Warehouse

Berndt, M.P.

1993-01-01

Groundwater quality at and near a landfill southwest of Tallahassee, Florida, where sludge from a municipal sewage-treatment plant was also applied, was assessed by sampling 21 monitoring wells and analyzing for various constituents. Water quality in the Upper Floridan aquifer at the site was compared to the water quality of 20 background wells in Leon County. Water quality in all samples from wells at the site was evaluated in relation to the landfill and sludge-spreading and nonsludge- spreading areas. Results from nonparametric statistical tests showed that potassium and nitrate concentrations were significantly different in samples from the Upper Floridan aquifer at the site and in samples from background wells. Median potassium concentrations were 0.7 mg/L in samples collected at the site and 0.4 mg/L in samples collected from background wells, whereas median nitrate concentration was 6.48 mg/L at the site and 0.51 mg/L in background wells. Graphical comparison of concentration distributions in six categories of wells; upgradient, landfill, adjacent to the landfill, downgradient onsite, downgradient offsite, and from background wells in Leon County, indicated that sodium, bicarbonate, sulfate, iron, manganese, dissolved solids, and specific conductance had highest concentrations in water from wells within the landfill. Nitrate concentrations were lowest in samples from wells in the landfill compared to the other categories. Concentrations of trace metals and organic constituents were mostly below detection limits although State maximum contaminant levels of 1.0 microg/L for benzene and vinyl chloride and 3.0 microg/L for tetrachloroethene were exceeded in water from some wells. Nitrate and chloride concentrations were significantly different in sludge-spreading and nonsludge-spreading areas. Median nitrate and chloride concentrations of 6.9 microg/L and 2.9 microg/L were detected in groundwater in sludge-spreading areas compared to 1.1 mg/L and 1.8 mg/L in nonsludge-spreading areas.

Biodegradation of crude oil into nonvolatile organic acids in a contaminated aquifer near Bemidji, Minnesota

USGS Publications Warehouse

Thorn, K.A.; Aiken, G.R.

1998-01-01

As the result of a pipeline burst, a body of light aliphatic crude oil floats atop the groundwater in a shallow sand and gravel aquifer in a remote area outside Bemidji, Minnesota. Biodegradation has resulted in the formation of a plume of DOC downgradient from the oil body. Groundwater has also been contaminated in an area known as the spray zone, from vertical infiltration of DOC resulting from biodegradation of crude oil in the overlying unsaturated zone. The majority of DOC in the contaminated groundwater is in the form of nonvolatile organic acids (NVOA's) which represent the partial oxidation products of the crude oil constituents. The NVOA's have been classified into three fractions according to their isolation on XAD resins: hydrophobic neutrals (HPO-N), hydrophobic acids (HPO-A) and hydrophilic acids (HPI-A). These fractions of NVOA's were isolated from a well downgradient from the oil body (well 530; DOC=21 mg C/l), from a well in the spray zone (well 603; DOC=15 mg C/l) and from an uncontaminated well upgradient of the oil body where the naturally occurring DOC is 2.9 mg C/l (well 310). The three sets of NVOA's were characterized by elemental analyses, molecular weight determinations, 14C ages and liquid phase 1H and 13C NMR. The crude oil and the saturate, aromatic, resin and asphaltene fractions of the crude oil were similarly analyzed by elemental analysis and NMR. The NVOA's from the contaminated wells were clearly distinguishable from the naturally occurring groundwater DOC. Based upon molecular weights, sulfur contents, aromaticities and the presence of methyl groups bonded to aromatic rings, the characterization data suggests that the NVOA's originate from the C18 or greater alkylaromatic, naphthenoaromatic and sulfur-containing constituents of the crude oil, including possibly the resins and asphaltenes.

Investigation of Contaminated Groundwater at Solid Waste Management Unit 12, Naval Weapons Station Charleston, North Charleston, South Carolina, 2008

USGS Publications Warehouse

Vroblesky, Don A.; Petkewich, Matthew D.

2009-01-01

The U.S. Geological Survey and the Naval Facilities Engineering Command Southeast investigated natural and engineered remediation of chlorinated volatile organic compound (VOC) groundwater contamination at Solid Waste Management Unit 12 at the Naval Weapons Station Charleston, North Charleston, South Carolina, beginning in 2000. The primary contaminants of interest in the study are tetrachloroethene, 1,1,1-trichloroethane, trichloroethene, cis-1,2-dichloroethene, vinyl chloride, 1,1-dichloroethane, and 1,1-dichloroethene. Engineered remediation aspects at the site consist of a zero-valent-iron permeable reactive barrier (PRB) installed in December 2002 intercepting the contamination plume and a phytoremediation test stand of loblolly pine trees planted in the source area in May 2003. The U.S. Geological Survey planted an additional phytoremediation test stand of loblolly pine trees on the upgradient side of the southern end of the PRB in February 2008. At least once during the summer, however, the trees were inadvertently mowed during lawn cutting activity. The PRB along the main axis of the contaminant plume appears to be actively removing contamination. In contrast to the central area of the PRB, the data from the southern end of the PRB indicate that contaminants are moving around the PRB. Concentrations in wells upgradient from the PRB showed a general decrease in VOC concentrations. VOC concentrations in some wells in the forest downgradient from the PRB showed a sharp increase in 2005, followed by a decrease in 2006. Farther downgradient in the forest, the VOC concentrations began to increase in 2007 and continued to increase into 2008. The VOC-concentration changes in groundwater beneath the forest appear to indicate movement of a groundwater-contaminant pulse through the forest. It also is possible that the data may represent lateral shifting of the plume in response to changes in groundwater-flow direction.

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

NASA Astrophysics Data System (ADS)

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

2001-05-01

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

Effect of treated-sewage contamination upon bacterial energy charge, adenine nucleotides, and DNA content in a sandy aquifer on cape cod

USGS Publications Warehouse

Metge, D.W.; Brooks, M.H.; Smith, R.L.; Harvey, R.W.

1993-01-01

Changes in adenylate energy charge (EC(A)) and in total adenine nucleotides (A(T)) and DNA content (both normalized to the abundance of free- living, groundwater bacteria) in response to carbon loading were determined for a laboratory-grown culture and for a contaminated aquifer. The latter study involved a 3-km-long transect through a contaminant plume resulting from continued on-land discharge of secondary sewage to a shallow, sandy aquifer on Cape Cod, Mass. With the exception of the most contaminated groundwater immediately downgradient from the contaminant source, DNA and adenylate levels correlated strongly with bacterial abundance and decreased exponentially with increasing distance downgradient. EC(A)s (0.53 to 0.60) and the ratios of ATP to DNA (0.001 to 0.003) were consistently low, suggesting that the unattached bacteria in this groundwater study are metabolically stressed, despite any eutrophication that might have occurred. Elevated EC(A)s (up to 0.74) were observed in glucose-amended groundwater, confirming that the metabolic state of this microbial community could be altered. In general, per-bacterium DNA and ATP contents were approximately twofold higher in the plume than in surrounding groundwater, although EC(A) and per-bacterium levels of A(T) differed little in the plume and the surrounding uncontaminated groundwater. However, per-bacterium levels of DNA and A(T) varied six- and threefold, respectively, during a 6-h period of decreasing growth rate for an unidentified pseudomonad isolated from contaminated groundwater and grown in batch culture. These data suggest that the DNA content of groundwater bacteria may be more sensitive than their A(T) to the degree of carbon loading, which may have significant ramifications in the use of nucleic acids and adenine nucleotides for estimating the metabolic status of bacterial communities within more highly contaminated aquifers.

Ammonium transport and reaction in contaminated groundwater: Application of isotope tracers and isotope fractionation studies

USGS Publications Warehouse

Böhlke, J.K.; Smith, Richard L.; Miller, Daniel N.

2006-01-01

Ammonium (NH4+) is a major constituent of many contaminated groundwaters, but its movement through aquifers is complex and poorly documented. In this study, processes affecting NH4+ movement in a treated wastewater plume were studied by a combination of techniques including large‐scale monitoring of NH4+ distribution; isotopic analyses of coexisting aqueous NH4+, NO3−, N2, and sorbed NH4+; and in situ natural gradient 15NH4+tracer tests with numerical simulations of 15NH4+, 15NO3−, and 15N2 breakthrough data. Combined results indicate that the main mass of NH4+ was moving downgradient at a rate about 0.25 times the groundwater velocity. Retardation factors and groundwater ages indicate that much of the NH4+ in the plume was recharged early in the history of the wastewater disposal. NO3− and excess N2 gas, which were related to each other by denitrification near the plume source, were moving downgradient more rapidly and were largely unrelated to coexisting NH4+. The δ15N data indicate areas of the plume affected by nitrification (substantial isotope fractionation) and sorption (no isotope fractionation). There was no conclusive evidence for NH4+‐consuming reactions (nitrification or anammox) in the anoxic core of the plume. Nitrification occurred along the upper boundary of the plume but was limited by a low rate of transverse dispersive mixing of wastewater NH4+ and O2 from overlying uncontaminated groundwater. Without induced vertical mixing or displacement of plume water with oxic groundwater from upgradient sources, the main mass of NH4+ could reach a discharge area without substantial reaction long after the more mobile wastewater constituents are gone. Multiple approaches including in situ isotopic tracers and fractionation studies provided critical information about processes affecting NH4+ movement and N speciation.

Modeling the influence of coupled mass transfer processes on mass flux downgradient of heterogeneous DNAPL source zones

NASA Astrophysics Data System (ADS)

Yang, Lurong; Wang, Xinyu; Mendoza-Sanchez, Itza; Abriola, Linda M.

2018-04-01

Sequestered mass in low permeability zones has been increasingly recognized as an important source of organic chemical contamination that acts to sustain downgradient plume concentrations above regulated levels. However, few modeling studies have investigated the influence of this sequestered mass and associated (coupled) mass transfer processes on plume persistence in complex dense nonaqueous phase liquid (DNAPL) source zones. This paper employs a multiphase flow and transport simulator (a modified version of the modular transport simulator MT3DMS) to explore the two- and three-dimensional evolution of source zone mass distribution and near-source plume persistence for two ensembles of highly heterogeneous DNAPL source zone realizations. Simulations reveal the strong influence of subsurface heterogeneity on the complexity of DNAPL and sequestered (immobile/sorbed) mass distribution. Small zones of entrapped DNAPL are shown to serve as a persistent source of low concentration plumes, difficult to distinguish from other (sorbed and immobile dissolved) sequestered mass sources. Results suggest that the presence of DNAPL tends to control plume longevity in the near-source area; for the examined scenarios, a substantial fraction (43.3-99.2%) of plume life was sustained by DNAPL dissolution processes. The presence of sorptive media and the extent of sorption non-ideality are shown to greatly affect predictions of near-source plume persistence following DNAPL depletion, with plume persistence varying one to two orders of magnitude with the selected sorption model. Results demonstrate the importance of sorption-controlled back diffusion from low permeability zones and reveal the importance of selecting the appropriate sorption model for accurate prediction of plume longevity. Large discrepancies for both DNAPL depletion time and plume longevity were observed between 2-D and 3-D model simulations. Differences between 2- and 3-D predictions increased in the presence of sorption, especially for the case of non-ideal sorption, demonstrating the limitations of employing 2-D predictions for field-scale modeling.

Numerical investigation on properties of attack angle for an opposing jet thermal protection system

NASA Astrophysics Data System (ADS)

Lu, Hai-Bo; Liu, Wei-Qiang

2012-08-01

The three-dimensional Navier—Stokes equation and the k-in viscous model are used to simulate the attack angle characteristics of a hemisphere nose-tip with an opposing jet thermal protection system in supersonic flow conditions. The numerical method is validated by the relevant experiment. The flow field parameters, aerodynamic forces, and surface heat flux distributions for attack angles of 0°, 2°, 5°, 7°, and 10° are obtained. The detailed numerical results show that the cruise attack angle has a great influence on the flow field parameters, aerodynamic force, and surface heat flux distribution of the supersonic vehicle nose-tip with an opposing jet thermal protection system. When the attack angle reaches 10°, the heat flux on the windward generatrix is close to the maximal heat flux on the wall surface of the nose-tip without thermal protection system, thus the thermal protection has failed.

Method for providing mirror surfaces with protective strippable polymeric film

DOEpatents

Edwards, Charlene C.; Day, Jack R.

1980-01-01

This invention is a method for forming a protective, strippable, elastomeric film on a highly reflective surface. The method is especially well suited for protecting diamond-machined metallic mirrors, which are susceptible not only to abrasion and mechanical damage but also to contamination and corrosion by various fluids. In a typical use of the invention, a diamond-machined copper mirror surface is coated uniformly with a solution comprising a completely polymerized and completely cured thermoplastic urethane elastomer dissolved in tetrahydrofuran. The applied coating is evaporated to dryness, forming a tough, adherent, impermeable, and transparent film which encapsulates dust and other particulates on the surface. The film may be left in place for many months. When desired, the film may be stripped intact, removing the entrapped particulates and leaving no residue on the mirror surface.

Sustainable yields from large diameter wells in shallow weathered aquifers

NASA Astrophysics Data System (ADS)

Rushton, K. R.; de Silva, C. S.

2016-08-01

Large diameter wells in shallow weathered aquifers provide a valuable source of water for domestic and agricultural purposes in many locations including the Indian subcontinent. However, when used for irrigation, these wells often fail towards the end of the dry season. By considering two case studies in the dry and intermediate rainfall zones of Sri Lanka, reasons for the limited yield of these wells are identified. The first case study is concerned with a sloping catchment; a significant proportion of the precipitation during the rainy season either becomes runoff or passes down-gradient through the aquifer and is discharged at the ground surface. Furthermore, during the dry season, groundwater discharge continues. In the second case study the topography is generally flat but, even though the aquifer fills most years during the rainy season, there is often only sufficient water to irrigate about half of each farmer's holding. These investigations are based on field information and the development of conceptual and computational models. Of critical importance in assessing the long term yield of a well is the formation of a seepage face on the side of the well, with the water table a significant distance above the pumping water level. Consequently the water table may only be lowered to about half the depth of the well. The paper concludes with recommendations for the exploitation of groundwater from shallow weathered aquifers to minimise the risk of failure during the dry season.

Description and hydrogeologic evaluation of nine hazardous-waste sites in Kansas, 1984-86

USGS Publications Warehouse

Hart, R.J.; Spruill, T.B.

1988-01-01

Wastes generated at nine hazardous-waste sites in Kansas were disposed in open pits, 55-gal drums, or large storage tanks. These disposal methods have the potential to contaminate groundwater beneath the sites, the soil on the sites, and nearby surface water bodies. Various activities on the nine sites included production of diborane, transformer oil waste, production of soda ash, use of solvents for the manufacture of farm implements, reclamation of solvents and paints, oil-refinery wastes, meat packaging, and the manufacture and cleaning of tanker-truck tanks. Monitoring wells were installed upgradient and downgradient from the potential contamination source on each site. Strict decontamination procedures were followed to prevent cross contamination between well installations. Air-quality surveys were made on each site before other investigative procedures started. Hydrogeologic investigative techniques, such as terrain geophysical surveys, gamma-ray logs, and laboratory permeameter tests, were used. Groundwater level measurements provide data to determine the direction of flow. Groundwater contamination detected under the sites posed the greatest threat to the environment because of possible migration of contaminants by groundwater flow. Concentrations of volatile organic compounds, polynuclear aromatic hydrocarbons, and trace metals were detected in the groundwater at several of the sites. Many of the same compounds detected in the groundwater also were detected in soil and bed-material samples collected onsite or adjacent to the sites. Several contaminants were detected in background samples of groundwater and soil. (USGS)

40 CFR 141.73 - Filtration.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS Filtration and Disinfection § 141.73 Filtration. A public water system that uses a surface water source or a ground water source under the direct influence of surface water...

40 CFR 264.220 - Applicability.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES (CONTINUED) STANDARDS FOR OWNERS AND OPERATORS OF HAZARDOUS WASTE TREATMENT, STORAGE, AND DISPOSAL FACILITIES Surface Impoundments... that use surface impoundments to treat, store, or dispose of hazardous waste except as § 264.1 provides...

Derivation of site-specific surface water quality criteria for the protection of aquatic ecosystems near a Korean military training facility.

PubMed

Jeong, Seung-Woo; An, Youn-Joo

2014-01-01

This study suggested the first Korean site-specific ecological surface water quality criteria for the protection of ecosystems near an artillery range at a Korean military training facility. Surface water quality (SWQ) criteria in Korea address human health protection but do not encompass ecological criteria such as limits for metals and explosives. The first objective of this study was to derive site-specific SWQ criteria for the protection of aquatic ecosystems in Hantan River, Korea. The second objective was to establish discharge criteria for the artillery range to protect the aquatic ecosystems of Hantan River. In this study, we first identified aquatic organisms living in the Hantan River, including fishes, reptiles, invertebrates, phytoplankton, zooplankton, and amphibians. Second, we collected ecotoxicity data for these aquatic organisms and constructed an ecotoxicity database for Cd, Cu, Zn, TNT, and RDX. This study determined the ecological maximum permissible concentrations for metals and explosives based on the ecotoxicity database and suggested ecological surface water quality criteria for the Hantan River by considering analytical detection limits. Discharge limit criteria for the shooting range were determined based on the ecological surface water quality criteria suggested for Hantan River with further consideration of the dilution of the contaminants discharged into the river.

Effects of highway deicing chemicals on shallow unconsolidated aquifers in Ohio--final report

USGS Publications Warehouse

Kunze, Allison E.; Sroka, Bernard N.

2004-01-01

As a result of concerns about salt intrusion into drinking water aquifers, the effects of highway deicing chemicals on shallow aquifers were studied at eight locations in Ohio from 1988 through 2002. The study was done by the U.S. Geological Survey, in cooperation with the Ohio Department of Transportation and the Federal Highway Administration. Sites were selected along major undivided highways where drainage is by open ditches and ground-water flow is approximately perpendicular to the highway. Records of deicer application rates were kept, and apparent movement of deicing chemicals through shallow, unconsolidated aquifers was monitored by means of periodic measurements of specific conductance and concentrations of dissolved sodium, calcium, and chloride. The State routes monitored were the following: State Route (SR) 3 in Ashland County, SR 84 in Ashtabula County, SR 29 in Champaign County, SR 4 in Clark County, SR 2 in Lucas County, SR 104 in Pickaway County, SR 14 in Portage County, and SR 97 in Richland County. The study began in 1988 with background data collection, extensive literature review, and site selection. This process, including drilling of wells at numerous test sites and the eight selected sites, lasted 3 years. Routine groundwater sampling at 4- to 6-week intervals began in January 1991 and continued through September 1999. A multilevel, passive flow ground-water sampling device was constructed and used. Other conditions monitored on a regular basis included ground-water level (monitored continuously), specific conductance, air and soil temperature, precipitation,chloride concentration in soil samples, and deicing-chemical application times and rates. Evidence from water analysis, specific-conductance measurements, and surface-geophysical measurements indicates that three of the eight sites (Ashtabula County, Lucas County, and Portage County sites) were affected by direct application of deicing chemicals. Climatic data collected during the study show that cold weather, and therefore deicing-chemical application rates, varied from south to north across the State. As a consequence, only minor traces of dissolved chloride (mean, 2443 mg/L (milligrams per liter)) above background concentrations (mean, 1323 mg/L) were determined in ground-water samples from the southernmost sites (approximately 39?30' to 40? N latitudeChampaign County, Clark County, and Pickaway County). At the Ashland and Richland County sites (approximately 40?30' N latitude), dissolved-chloride concentrations increased above background concentrations only intermittently (mean background concentrations 441 mg/L, rising to a mean of 4056 mg/L in downgradient wells). At the northernmost sites (41? 30' to 42? N latitudeLucas County, Portage County, and Ashtabula County), deicing-chemical application was consistent throughout the winter, and downgradient dissolved-chloride concentrations (mean, 124345 mg/L) rarely returned to background concentrations (mean, 737 mg/L) throughout the study period. Other factors than application rate that may affect the movement of deicing chemicals through an aquifer were precipitation amounts, the types of subsurface materials, ground-water velocity and gradient, hydraulic conductivity, soil type, land use, and Ohio Department of Transportation deicing priority.

Nodal surface semimetals: Theory and material realization

NASA Astrophysics Data System (ADS)

Wu, Weikang; Liu, Ying; Li, Si; Zhong, Chengyong; Yu, Zhi-Ming; Sheng, Xian-Lei; Zhao, Y. X.; Yang, Shengyuan A.

2018-03-01

We theoretically study the three-dimensional topological semimetals with nodal surfaces protected by crystalline symmetries. Different from the well-known nodal-point and nodal-line semimetals, in these materials, the conduction and valence bands cross on closed nodal surfaces in the Brillouin zone. We propose different classes of nodal surfaces, both in the absence and in the presence of spin-orbit coupling (SOC). In the absence of SOC, a class of nodal surfaces can be protected by space-time inversion symmetry and sublattice symmetry and characterized by a Z2 index, while another class of nodal surfaces are guaranteed by a combination of nonsymmorphic twofold screw-rotational symmetry and time-reversal symmetry. We show that the inclusion of SOC will destroy the former class of nodal surfaces but may preserve the latter provided that the inversion symmetry is broken. We further generalize the result to magnetically ordered systems and show that protected nodal surfaces can also exist in magnetic materials without and with SOC, given that certain magnetic group symmetry requirements are satisfied. Several concrete nodal-surface material examples are predicted via the first-principles calculations. The possibility of multi-nodal-surface materials is discussed.

Nevada National Security Site Integrated Groundwater Sampling Plan, Revision 1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wilborn, Bill R.; Boehlecke, Robert F.

The purpose is to provide a comprehensive, integrated approach for collecting and analyzing groundwater samples to meet the needs and objectives of the DOE/EM Nevada Program’s UGTA Activity. Implementation of this Plan will provide high-quality data required by the UGTA Activity for ensuring public protection in an efficient and cost-effective manner. The Plan is designed to ensure compliance with the UGTA Quality Assurance Plan (QAP) (NNSA/NFO, 2015); Federal Facility Agreement and Consent Order (FFACO) (1996, as amended); and DOE Order 458.1, Radiation Protection of the Public and the Environment (DOE, 2013). The Plan’s scope comprises sample collection and analysis requirementsmore » relevant to assessing both the extent of groundwater contamination from underground nuclear testing and impact of testing on water quality in downgradient communities. This Plan identifies locations to be sampled by CAU and location type, sampling frequencies, sample collection methodologies, and the constituents to be analyzed. In addition, the Plan defines data collection criteria such as well purging, detection levels, and accuracy requirements/recommendations; identifies reporting and data management requirements; and provides a process to ensure coordination between NNSS groundwater sampling programs for sampling analytes of interest to UGTA. Information used in the Plan development—including the rationale for selection of wells, sampling frequency, and the analytical suite—is discussed under separate cover (N-I, 2014) and is not reproduced herein. This Plan does not address compliance for those wells involved in a permitted activity. Sampling and analysis requirements associated with these wells are described in their respective permits and are discussed in NNSS environmental reports (see Section 5.2). In addition, sampling for UGTA CAUs that are in the Closure Report (CR) stage are not included in this Plan. Sampling requirements for these CAUs are described in the CR. Frenchman Flat is currently the only UGTA CAU in the CR stage. Sampling requirements for this CAU are described in Underground Test Area (UGTA) Closure Report for Corrective Action Unit 98: Frenchman Flat Nevada National Security Site, Nevada (NNSA/NFO, 2016).« less

Density-based global sensitivity analysis of sheet-flow travel time: Kinematic wave-based formulations

NASA Astrophysics Data System (ADS)

Hosseini, Seiyed Mossa; Ataie-Ashtiani, Behzad; Simmons, Craig T.

2018-04-01

Despite advancements in developing physics-based formulations to estimate the sheet-flow travel time (tSHF), the quantification of the relative impacts of influential parameters on tSHF has not previously been considered. In this study, a brief review of the physics-based formulations to estimate tSHF including kinematic wave (K-W) theory in combination with Manning's roughness (K-M) and with Darcy-Weisbach friction formula (K-D) over single and multiple planes is provided. Then, the relative significance of input parameters to the developed approaches is quantified by a density-based global sensitivity analysis (GSA). The performance of K-M considering zero-upstream and uniform flow depth (so-called K-M1 and K-M2), and K-D formulae to estimate the tSHF over single plane surface were assessed using several sets of experimental data collected from the previous studies. The compatibility of the developed models to estimate tSHF over multiple planes considering temporal rainfall distributions of Natural Resources Conservation Service, NRCS (I, Ia, II, and III) are scrutinized by several real-world examples. The results obtained demonstrated that the main controlling parameters of tSHF through K-D and K-M formulae are the length of surface plane (mean sensitivity index T̂i = 0.72) and flow resistance (mean T̂i = 0.52), respectively. Conversely, the flow temperature and initial abstraction ratio of rainfall have the lowest influence on tSHF (mean T̂i is 0.11 and 0.12, respectively). The significant role of the flow regime on the estimation of tSHF over a single and a cascade of planes are also demonstrated. Results reveal that the K-D formulation provides more precise tSHF over the single plane surface with an average percentage of error, APE equal to 9.23% (the APE for K-M1 and K-M2 formulae were 13.8%, and 36.33%, respectively). The superiority of Manning-jointed formulae in estimation of tSHF is due to the incorporation of effects from different flow regimes as flow moves downgradient that is affected by one or more factors including high excess rainfall intensities, low flow resistance, high degrees of imperviousness, long surfaces, steep slope, and domination of rainfall distribution as NRCS Type I, II, or III.

30 CFR 816.79 - Protection of underground mining.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Protection of underground mining. 816.79 Section 816.79 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PERMANENT PROGRAM PERFORMANCE STANDARDS PERMANENT PROGRAM PERFORMANCE STANDARDS-SURFACE MINING...

Modeling the protection afforded by burrows, cavities, and roosts during wildland surface fires

Treesearch

Anthony Bova; Matthew Dickinson

2009-01-01

Wildland surface fires produce many toxic and irritating compounds, such as formaldehyde and acrolein, and harmful gases such as carbon monoxide. Several factors influence the degree of protection offered by animal shelters against combustion products and heat.

30 CFR 816.79 - Protection of underground mining.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 3 2011-07-01 2011-07-01 false Protection of underground mining. 816.79 Section 816.79 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PERMANENT PROGRAM PERFORMANCE STANDARDS PERMANENT PROGRAM PERFORMANCE STANDARDS-SURFACE MINING...

Engineered Joint Lubrication for OA Prevention and Treatment

DTIC Science & Technology

2015-09-01

Williams, C. G., Khan, M., Manson, P. & Elisseeff, J .H. In vivo chondrogenesis of mesenchymal stem cells in photopolymerized hydrogel. Plast...protecting cells from free-radical damage20–22. Coating surfaces with HA may also physically protect the surfaces from cytokines and degrading enzymes...modification provides a biomimetic mechanism to concentrate HA on the surface. Numerous endogenous enzymes and reactive oxygen species can degrade HA

A Modified Surface Killing Assay (MSKA) as a Functional in vitro Assay for Identifying Protective Antibodies Against Pneumococcal Surface Protein A (PspA)

PubMed Central

Genschmer, Kristopher R.; Accavitti-Loper, Mary Ann; Briles, David E.

2013-01-01

Streptococcus pneumoniae causes otitis media, meningitis and pneumonia in patients worldwide; predominantly affecting young children, the elderly, and the immune compromised. Current vaccines against invasive pneumococcal disease are based on the polysaccharide capsules of the most clinically relevant serotypes. Due to serotype replacement, non-vaccine serotypes of S. pneumoniae have become more clinically relevant and as a result pneumococcal vaccines are becoming increasingly complex. These events emphasize the need to evaluate the potential for pneumococcal cross-reactive proteins to contribute to future vaccines. Antibody elicited by the immunization of humans with pneumococcal surface protein A (PspA) can passively protect mice from infection. However, robust in vitro functional assays for antibody to PspA are not available to predict the protective capacity of immune serum. For polysaccharide based vaccines, a standardized opsonophagocytosis killing assay (OPKA) is used. Antibody to PspA, however, does not work well in the standard OPKA. The present studies take advantage of past observations that phagocytosis is more efficient on tissue surfaces than in solution. In a modified surface killing assay (MSKA), monoclonal antibody to PspA, in the presence of complement, opsonized pneumococci for killing by phagocytes on an agar surface. Five monoclonal antibodies to PspA were tested; three demonstrated increased amounts of killing compared to the diluent control and protected mice by passive protection against type 3 pneumococci. The two antibodies that were not functional in the MSKA also failed to protect mice. Thus, an MSKA might be useful as a functional assay for immunity to PspA. PMID:24211169

Characterization of SeseC_01411 as a surface protective antigen of Streptococcus equi ssp. zooepidemicus.

PubMed

Xie, Honglin; Wei, Zigong; Ma, Chunquan; Li, Shun; Liu, Xiaohong; Fu, Qiang

2018-06-01

Streptococcus equi ssp. zooepidemicus (Streptococcus zooepidemicus, SEZ) is a commensal bacterium related to opportunistic infections of many species, including humans, dogs, cats, and pigs. SeseC_01411 has been proven to be immunogenic. However, its protective efficacy remained to be evaluated. In the present study, the purified recombinant SeseC_01411 could elicit a strong humoral antibody response and protect against lethal challenge with virulent SEZ in mice. Our finding confirmed that SeseC_01411 distributes on the surface of SEZ. In addition, the hyperimmune sera against SeseC_01411 could efficiently kill the bacteria in the phagocytosis test. The present study identified the immunogenic protein, SeseC_01411, as a novel surface protective antigen of SEZ. Copyright © 2018 Elsevier Ltd. All rights reserved.

Overload protection: avoidance response to heavy plantar surface loading.

PubMed

Robbins, S E; Hanna, A M; Gouw, G J

1988-02-01

Current footwear which are designed for use in running are examples of intentional biomechanical model integration into device design. The inadequacy of this footwear in protecting against injury is postulated to be due to fixation on inadequate models of locomotory biomechanics that do not provide for feedback control; in particular, an hypothesized plantar surface sensory-mediated feedback control system, which imparts overload protection during locomotion. A heuristic approach was used to identify the hypothesized system. A random series of loads (0 to 164 kg) was applied to the knee flexed at 90 degrees. In this testing system, plantar surface avoidance behavior was the difference between the sum of the leg weight and the load applied to the knee, and the load measured at the plantar surface; this was produced by activation of hip flexors. Significant avoidance behavior was found in all of the subjects (P less than 0.001). On all surfaces tested, including modern athletic footwear (P less than 0.001), its magnitude increased directly in relation to the load applied to the knee (P less than 0.001). There were significant differences in avoidance behavior in relation to the weight-bearing surfaces tested (P less than 0.05). With the identification of a feedback control system which would serve to moderate loading during locomotion, an explanation is provided as to why current athletic footwear do not protect and may be injurious; thus allowing the design of footwear which may be truly protective.

The Face that Launched a Thousand Slips

NASA Technical Reports Server (NTRS)

Moore, J. M.; Howard, A. D.; Schenk, P.; Thomas, P. C.

2013-01-01

Helene, (approximately 17.6 kilometers mean radius) is an L4 Trojan co-orbital of Saturn's moon Dione. Its hemisphere features an unusual morphology consisting of broad depressions and a generally smooth surface patterned with streaks and grooves. The streaks appear to be oriented down-gradient, as are the grooves. This pattern suggests intensive mass-wasting as a dominant process on the leading hemisphere. Kilometer-scale impact craters are very sparse on the leading hemisphere other than the degraded kilometer-scale basins defining the overall satellite shape, and many small craters have a diffuse appearance suggesting ongoing mass wasting. Thus mass wasting must dominate surface-modifying processes at present. In fact, the mass wasting appears to have been sufficient in magnitude to narrow the divides between adjacent basins to narrow septa, similar, but in lower relief, to the honeycomb pattern of Hyperion. The prominent groves occur primarily near topographic divides and appear have cut into a broad, slightly lower albedo surface largely conforming to the present topography but elevated a few meters above the smooth surfaces undergoing mass wasting flow. Low ridges and albedo markings on the surface suggest surface flow of materials traveling up to several kilometers. Diffusive mass wasting produces smooth surfaces - such a pattern characterizes most of the low-lying surfaces. The grooves, however, imply that the transport process is advective at those locations where they occur, that is, erosion tends to concentrate along linear pathways separated by divides. In fact, in many places grooves have a fairly regular spacing of 125-160 meters, defining a characteristic erosional scale. Several questions are prompted by the unusual morphology of Helene: 1) What is the nature of the surface materials? 2) Are the transport processes gradual or catastrophic motion from one or a few events? 3) What mechanisms drive mass wasting and groove development? 4) Have the formative processes been active in the recent past? 5) Finally, is the surface accreting or eroding? The smooth character of the leading edge hemisphere of Helene and the dominance of mass wasting suggest that the surface is composed of fine-grained debris, probably dominated by dust-size to small gravel particles. The Lagrangian points of saturnian satellites are locations where planetesimals might have accreted to form co-orbital satellites such as and they may capture ejecta from their master moon. Published models suggest that Helene is a site of net accretion, but we find no extant explanation for the dominance of fine grain sizes for the surface (and probable subsurface) composition of Helene and the other Lagrangian satellites. Observation of the mass wasting tracks on Helene suggests the presence of well-defined streams of debris with low bordering levees that may be depositional features or remnants of the dissected higher surface. Some flows in grazing illumination appear to have a convex cross-section. This mass-flow morphology might be consistent with the occurrence of large-scale flow events, but which might have occurred through rapid emplacement or slow glacier-like creep. On the other hand, small craters appear to have been "softened" by creep-like processes, indicating ongoing mass wasting.

Sanitary protection zoning based on time-dependent vulnerability assessment model - case examples at two different type of aquifers

NASA Astrophysics Data System (ADS)

Živanović, Vladimir; Jemcov, Igor; Dragišić, Veselin; Atanacković, Nebojša

2017-04-01

Delineation of sanitary protection zones of groundwater source is a comprehensive and multidisciplinary task. Uniform methodology for protection zoning for various type of aquifers is not established. Currently applied methods mostly rely on horizontal groundwater travel time toward the tapping structure. On the other hand, groundwater vulnerability assessment methods evaluate the protective function of unsaturated zone as an important part of groundwater source protection. In some particular cases surface flow might also be important, because of rapid transfer of contaminants toward the zones with intense infiltration. For delineation of sanitary protection zones three major components should be analysed: vertical travel time through unsaturated zone, horizontal travel time through saturated zone and surface water travel time toward intense infiltration zones. Integrating the aforementioned components into one time-dependent model represents a basis of presented method for delineation of groundwater source protection zones in rocks and sediments of different porosity. The proposed model comprises of travel time components of surface water, as well as groundwater (horizontal and vertical component). The results obtained using the model, represent the groundwater vulnerability as the sum of the surface and groundwater travel time and corresponds to the travel time of potential contaminants from the ground surface to the tapping structure. This vulnerability assessment approach do not consider contaminant properties (intrinsic vulnerability) although it can be easily improved for evaluating the specific groundwater vulnerability. This concept of the sanitary protection zones was applied at two different type of aquifers: karstic aquifer of catchment area of Blederija springs and "Beli Timok" source of intergranular shallow aquifer. The first one represents a typical karst hydrogeological system with part of the catchment with allogenic recharge, and the second one, the groundwater source within shallow intergranular alluvial aquifer, dominantly recharged by river bank filtration. For sanitary protection zones delineation, the applied method has shown the importance of introducing all travel time components equally. In the case of the karstic source, the importance of the surface flow toward ponor zones has been emphasized, as a consequence of rapid travel time of water in relation to diffuse infiltration from autogenic part. When it comes to the shallow intergranular aquifer, the character of the unsaturated zone gets more prominent role in the source protection, as important buffer of the vertical movement downward. The applicability of proposed method has been shown regardless of the type of the aquifer, and at the same time intelligible results of the delineated sanitary protection zones are possible to validate with various methods. Key words: groundwater protection zoning, time dependent model, karst aquifer, intergranular aquifer, groundwater source protection

A unified view of convective transports by stratocumulus clouds, shallow cumulus clouds, and deep convection

NASA Technical Reports Server (NTRS)

Randall, David A.

1990-01-01

A bulk planetary boundary layer (PBL) model was developed with a simple internal vertical structure and a simple second-order closure, designed for use as a PBL parameterization in a large-scale model. The model allows the mean fields to vary with height within the PBL, and so must address the vertical profiles of the turbulent fluxes, going beyond the usual mixed-layer assumption that the fluxes of conservative variables are linear with height. This is accomplished using the same convective mass flux approach that has also been used in cumulus parameterizations. The purpose is to show that such a mass flux model can include, in a single framework, the compensating subsidence concept, downgradient mixing, and well-mixed layers.

Superfund record of decision (EPA Region 1): Peterson/Puritan Site, Operable Unit 1, Cumberland/Lincoln, RI, September 1993

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1993-09-01

This Decision Document presents the selected remedial action for the Peterson/Puritan, Inc. Superfund Site, Operable Unit 1, in Cumberland and Lincoln, Rhode Island. Operable Unit 1 contains two remediation areas. The CCL remediation area, a source of volatile organic contamination, includes the former Peterson/Puritan, Inc. facility, which is the Site's namesake (currently the CCL Custom Manufacturing facility, and referred to as CCL). The PAC remediation area includes the Pacific Anchor Chemical Corporation (PAC ) facility (formerly the Lonza and Universal Chemical Company facility), which is a source of arsenic and volatile organic contamination. Each remediation area is further split intomore » source and downgradient area components, respectively.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

The 20-acre White Farm Equipment Dump site is an active landfill near the north border of Charles City in Floyd County, Iowa. Drainage from the site toward the northwest and south feeds into adjacent wetland areas. The Charles City municipal wells, located 700 feet east of the site, obtain water from the deep, confined Cedar Valley aquifer. Additionally, six shallow drinking water wells that draw from an uncontrolled water table are 1,000 feet downgradient from the site. Intermittently since 1971, approximately 650,000 cubic yards of wet scrubber sludges, foundry sands, baghouse dusts, and other industrial wastes were disposed of onsite.more » The primary contaminants of concern affecting the soil, debris, and ground water are VOCs including benzene and toluene; and metals including arsenic, lead, and chromium.« less

Flow and geochemistry along shallow ground-water flowpaths in an agricultural area in southeastern Wisconsin

USGS Publications Warehouse

Saad, D.A.; Thorstenson, D.C.

1998-01-01

Ground water recharging at mid- and downgradient wells is oxic and contains dissolved nitrate, whereas the ground water discharging to the stream is anoxic and contains dissolved ammonium. Redox environments were defined at each well on the basis of relative concentrations of various dissolved redox-active species. Chemically permissible flowpaths inferred from the observed sequence of redox environments at well sites are consistent with flowpaths in the ground-water flow model. The transition from nitrate in recharging ground water to ammonium in ground water discharging to the stream suggests the possibility of nitrate reduction along the flowpath. None of the techniques employed in this study, however, were able to prove the occurrence of this reaction.

Chlorine-36 in the Snake River Plain Aquifer at the Idaho National Engineering Laboratory; origin and implications

USGS Publications Warehouse

Beasley, T.M.; Cecil, L.D.; Sharma, P.; Kubik, P.W.; Fehn, U.; Mann, L.J.; Gove, H.E.

1993-01-01

Between 1952 and 1984, low-level radioactive waste was introduced directly into the Snake River Plain aquifer at the Idaho National Engineering Laboratory (INEL), Idaho Falls, Idaho. These wastes were generated, principally, at the nuclear fuel reprocessing facility on the site. Our measurements of 36C1 in monitoring and production well waters, downgradient from disposal wells and seepage ponds, found easily detectable, nonhazardous concentrations of this radionuclide from the point of injection to the INEL southern site boundary. Comparisons are made between 3H and 36Cl concentrations in aquifer water and the advantages of 36C1 as a tracer of subsurface-water dynamics at the site are discussed.

Waste-indicator and pharmaceutical compounds in landfill-leachate-affected ground water near Elkhart, Indiana, 2000-2002.

PubMed

Buszka, P M; Yeskis, D J; Kolpin, D W; Furlong, E T; Zaugg, S D; Meyer, M T

2009-06-01

Four wells downgradient from a landfill near Elkhart, Indiana were sampled during 2000-2002 to evaluate the presence of waste-indicator and pharmaceutical compounds in landfill-leachate-affected ground water. Compounds detected in leachate-affected ground water included detergent metabolites (p-nonylphenol, nonylphenol monoethoxylate, nonylphenol diethoxylate, and octylphenol monoethoxylate), plasticizers (ethanol-2-butoxy-phosphate and diethylphthalate), a plastic monomer (bisphenol A), disinfectants (1,4-dichlorobenzene and triclosan), an antioxidant (5-methyl-1H-benzotriazole), three fire-retardant compounds (tributylphosphate and tri(2-chloroethyl)phosphate, and tri(dichlorisopropyl)phosphate), and several pharmaceuticals and metabolites (acetaminophen, caffeine, cotinine, 1,7-dimethylxanthine, fluoxetine, and ibuprofen). Acetaminophen, caffeine, and cotinine detections confirm prior indications of pharmaceutical and nicotinate disposal in the landfill.

Surface and protective properties of dispersions of film-formers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Turishcheva, R.A.; Bakaleinikov, M.B.; Minkina, E.N.

1983-03-01

This article reports on studies of the surface and protective properties of 20% dispersions of film-formers most typically used in film-forming inhibited petroleum-base compositions (FIPC): solid hydrocarbons, fatty acid soaps, asphalt, polymers, natural resins, modified vegetable oils, and an inorganic thickening agent. Investigates the dispersions of Butosil and lithium stearate at respective concentrations of 10% and 8%, in view of the high thickening power of these film-formers. Classifies all of the studied FIPC film-forming components into 2 groups: those wth little thickening effect, a low level of adhesion-cohesion interaction, and a high level of surface and protective properties (the oxidizedmore » solid hydrocarbons and the polymers); and the film-formers that have a large thickening effect, a high level of adhesion-cohesion interaction, and a low level of surface and protective properties (the fatty acid soaps, the solid hydrocarbons, and Butosil). Recommends combining film-formers of both groups in developing new grades of FIPCs.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brahlek, Matthew; Koirala, Nikesh; Salehi, Maryam

Topological insulators (TI) are a phase of matter that host unusual metallic states on their surfaces. Unlike the states that exist on the surface of conventional materials, these so-called topological surfaces states (TSS) are protected against disorder-related localization effects by time reversal symmetry through strong spin-orbit coupling. By combining transport measurements, angle-resolved photo-emission spectroscopy and scanning tunneling microscopy, we show that there exists a critical level of disorder beyond which the TI Bi 2Se 3 loses its ability to protect the metallic TSS and transitions to a fully insulating state. The absence of the metallic surface channels dictates that theremore » is a change in material’s topological character, implying that disorder can lead to a topological phase transition even without breaking the time reversal symmetry. This observation challenges the conventional notion of topologically-protected surface states, and will provoke new studies as to the fundamental nature of topological phase of matter in the presence of disorder.« less

Hydrophobizing coatings for cultural heritage. A detailed study of resin/stone surface interaction

NASA Astrophysics Data System (ADS)

Fermo, P.; Cappelletti, G.; Cozzi, N.; Padeletti, G.; Kaciulis, S.; Brucale, M.; Merlini, M.

2014-07-01

Conservation of historical buildings is an important issue and the environmental conditions seriously affect the monument's stones. The protection of cultural heritage buildings and monuments by surface treatment with polymers is a common practice due to their ability to form a protective layer on the monument's surface as well as to control the transport of different fluids from the surface to the monument's interior. In this work, three different substrates were used: Carrara marble, Botticino limestone, and Angera stone. A commercially available Si-based resin (Alpha®SI30) was used as protective agent to improve the hydrophobicity features of the different tested materials. The surface properties of the coating and the relative interaction with the adopted stones were studied using different techniques such as contact angle measurements, electron microscope coupled with an energy dispersive spectrometer, X-ray photoelectron spectroscopy, atomic force microscopy, and attenuated total reflection infrared spectroscopy.

30 CFR 57.12003 - Trailing cable overload protection.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Trailing cable overload protection. 57.12003... Electricity Surface and Underground § 57.12003 Trailing cable overload protection. Individual overload protection or short circuit protection shall be provided for the trailing cables of mobile equipment. ...

Thickness determination of polymeric multilayer surface protection systems for concrete by means of pulse thermography

NASA Astrophysics Data System (ADS)

Altenburg, S. J.; Krankenhagen, R.; Bavendiek, F.

2017-02-01

For thickness determination of polymer based surface protection systems for concrete surfaces, so far only destructive measurement techniques are available. Pulse thermography appears to be well suited for non-destructive thickness evaluation in these systems. Here, we present first results of the development of a respective measurement and analysis procedure. Since surface protection systems consist of a number of layers, a model for the calculation of the surface temperature of a multi-layer structure on a semi-infinite (concrete) substrate in pulse thermography setup was developed. It considers semitransparency of the upmost layer and thermal losses at the surface. It also supports the use of an arbitrary temporal shape of the heating pulse to properly describe the measurement conditions for different heat sources. Simulations for one and three layers on the substrate are presented and first results from fitting the model to experimental data for thickness determination and verification of the model are presented.

36 CFR 292.13 - Standards.

Code of Federal Regulations, 2010 CFR

2010-07-01

...-fourth acre of surface, smelters, sand, gravel and aggregate processing plants, fabricating plants... entertainment. (c) Protection of roadsides. Provisions to protect natural scenic qualities and maintain... standard. (d) Protection of shorelines. Provisions to protect scenic qualities and reduce potentials for...

Mitigation of radiation induced surface contamination

DOEpatents

Klebanoff, Leonard E.; Stulen, Richard H.

2003-01-01

A process for mitigating or eliminating contamination and/or degradation of surfaces having common, adventitious atmospheric contaminants adsorbed thereon and exposed to radiation. A gas or a mixture of gases is introduced into the environment of a surface(s) to be protected. The choice of the gaseous species to be introduced (typically a hydrocarbon gas, water vapor, or oxygen or mixtures thereof) is dependent upon the contaminant as well as the ability of the gaseous species to bind to the surface to be protected. When the surface and associated bound species are exposed to radiation reactive species are formed that react with surface contaminants such as carbon or oxide films to form volatile products (e.g., CO, CO.sub.2) which desorb from the surface.

Issues and Consequences of Atomic Oxygen Undercutting of Protected Polymers in Low Earth Orbit

NASA Technical Reports Server (NTRS)

Banks, Bruce A.; Snyder, Aaron; Miller, Sharon K.; Demko, Rikako

2002-01-01

Hydrocarbon based polymers that are exposed to atomic oxygen in low Earth orbit are slowly oxidized which results in recession of their surface. Atomic oxygen protective coatings have been developed which are both durable to atomic oxygen and effective in protecting underlying polymers. However, scratches, pin window defects, polymer surface roughness and protective coating layer configuration can result in erosion and potential failure of protected thin polymer films even though the coatings are themselves atomic oxygen durable. This paper will present issues that cause protective coatings to become ineffective in some cases yet effective in others due to the details of their specific application. Observed in-space examples of failed and successfully protected materials using identical protective thin films will be discussed and analyzed. Proposed approaches to prevent the failures that have been observed will also be presented.

Protection of Mice against Plasmodium yoelii Sporozoite Challenge with P. yoelii Merozoite Surface Protein 1 DNA Vaccines

PubMed Central

Becker, Sylvia I.; Wang, Ruobing; Hedstrom, Richard C.; Aguiar, Joao C.; Jones, Trevor R.; Hoffman, Stephen L.; Gardner, Malcolm J.

1998-01-01

Immunization of mice with DNA vaccines encoding the full-length form and C and N termini of Plasmodium yoelii merozoite surface protein 1 provided partial protection against sporozoite challenge and resulted in boosting of antibody titers after challenge. In C57BL/6 mice, two DNA vaccines provided protection comparable to that of recombinant protein consisting of the C terminus in Freund’s adjuvant. PMID:9632624

Corrosion protection

DOEpatents

Brown, Donald W.; Wagh, Arun S.

2003-05-27

There has been invented a chemically bonded phosphate corrosion protection material and process for application of the corrosion protection material for corrosion prevention. A slurry of iron oxide and phosphoric acid is used to contact a warm surface of iron, steel or other metal to be treated. In the presence of ferrous ions from the iron, steel or other metal, the slurry reacts to form iron phosphates which form grains chemically bonded onto the surface of the steel.

Morphological changes of porphine films on graphite by perchloric and phosphoric electrolytes. An electrochemical-AFM study

NASA Astrophysics Data System (ADS)

Yivlialin, Rossella; Penconi, Marta; Bussetti, Gianlorenzo; Biroli, Alessio Orbelli; Finazzi, Marco; Duò, Lamberto; Bossi, Alberto

2018-06-01

Organic molecules have been proposed as promising candidates for electrode protection in acidic electrolytes. The use of tetraphenyl-porphines (H2TPP) as graphite surface-protecting agents in sulphuric acid (H2SO4) is one of the newest. With the aim of unveiling the mechanism of such a protective effect, in this paper we test the stability of a H2TPP thin film immersed in perchloric and phosphoric acid solutions that differently interact with porphyrins. The protective role of H2TPP is tested in the electrochemical potential range where the pristine graphite undergoes an oxidation process that erodes the surface and eventually exfoliate the stratified crystal. The electrochemical analysis is performed in a three-electrode cell, while the surface morphology is monitored ex-situ and in-situ by atomic force microscopy. Electrospray mass analysis is also employed to investigate the presence of H2TPP fragments in the solution. We find that the organic film is not stable in perchloric solution, while it is stable and avoids graphite surface corrosion in phosphoric acid solution. These results provide a rationale for the role played by free-base porphines in graphite protection.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tatur, I.R.; Prigul`skii, G.B.; Timokhin, I.A.

Enamel paints MS-17 and KhV-110 are used to protect drill bits during transportation and storage. But this requires the surface to be prepared carefully, which is often difficult under production conditions. Some of the promising anticorrosion agents are film-forming inhibited petroleum compounds (FIPC) - materials derived from high-temperature petroleum products blended with corrosion inhibitors and a solvent. Such compounds are used to protect unpainted and painted surfaces; this shortens the preservation process, and generally dispenses which depreservation. Further, they can be used to protect moist, wet, greasy, and rusted surfaces, and concealed inner areas where paint is difficult to apply.more » The purpose of this work was to obtain a film-forming inhibited petroleum compound that has high protective properties, can be applied on unprepared metal surfaces, and meets the following requirements: drill bit protection time during transportation and storage at least 24 months, coat adhesion to the metal at least of force 2, drop point > 90{degrees}C, the material must be applied by pneumatic spraying, in toxicity and inflammability the compound must be of class three, and coat drying time at 60{degrees}C not more than 12 min. The anticorrosion agents are described.« less

Method and coating composition for protecting and decontaminating surfaces

DOEpatents

Overhold, D C; Peterson, M D

1959-03-10

A protective coating useful in the decontamination of surfaces exposed to radioactive substances is described. This coating is placed on the surface before use and is soluble in water, allowing its easy removal in the event decontamination becomes necessary. Suitable coating compositions may be prepared by mixing a water soluble carbohydrate such as sucrose or dextrin, together with a hygroscopic agent such as calcium chloride or zinc chloride.

METHOD AND COATING COMPOSITION FOR PROTECTING AND DECONTAMINATING SURFACES

DOEpatents

Overhold, D.C.; Peterson, M.D.

1959-03-10

A protective coating useful in the decontamination of surfaces exposed to radioactive substances is presented. This coating is placed on the surface before use and is soluble in waters allowing its easy removal in the event decontamination becomes necessary. Suitable coating compositions may be prepared by mixing a water soluble carbohydrate such as sucrose or dextrin, together with a hygroscopic agent such as calcium chloride or zinc chloride.

Process for non-contact removal of organic coatings from the surface of paintings

NASA Technical Reports Server (NTRS)

Banks, Bruce A. (Inventor); Rutledge, Sharon K. (Inventor)

1995-01-01

The present invention discloses a method of removing organic protective coatings from a painting. In the present invention degraded protective coatings such as lacquers, acrylics, natural resins, carbons, soot, and polyurethane are safely removed from the surface of a painting without contact to the surface of the painting. This method can be used for restoration of paintings when they have been damaged, through age, fire, etc.

Surface protection in bio-shields via a functional soft skin layer: Lessons from the turtle shell.

PubMed

Shelef, Yaniv; Bar-On, Benny

2017-09-01

The turtle shell is a functional bio-shielding element, which has evolved naturally to provide protection against predator attacks that involve biting and clawing. The near-surface architecture of the turtle shell includes a soft bi-layer skin coating - rather than a hard exterior - which functions as a first line of defense against surface damage. This architecture represents a novel type of bio-shielding configuration, namely, an inverse structural-mechanical design, rather than the hard-coated bio-shielding elements identified so far. In the current study, we used experimentally based structural modeling and FE simulations to analyze the mechanical significance of this unconventional protection architecture in terms of resistance to surface damage upon extensive indentations. We found that the functional bi-layer skin of the turtle shell, which provides graded (soft-softer-hard) mechanical characteristics to the bio-shield exterior, serves as a bumper-buffer mechanism. This material-level adaptation protects the inner core from the highly localized indentation loads via stress delocalization and extensive near-surface plasticity. The newly revealed functional bi-layer coating architecture can potentially be adapted, using synthetic materials, to considerably enhance the surface load-bearing capabilities of various engineering configurations. Copyright © 2017 Elsevier Ltd. All rights reserved.

Behavior of energetic materials in ground water at an anti-tank range.

PubMed

Martel, Richard; Mailloux, Michel; Gabriel, Uta; Lefebvre, René; Thiboutot, Sonia; Ampleman, Guy

2009-01-01

An environmental issue has arisen with M-72 malfunction on anti-tank ranges because many of these rockets break into pieces without exploding on impact, dispersing their energetic materials content on the ground surface and exposing them to transport by infiltration of rainfall and snowmelt. A case study (1998--2005) at Arnhem Anti-Tank Range (Garrison Valcartier, Canada, in operation since the 1970s) revealed octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) contamination and traces of 1,3,5-trinitro-1,3,5-triazine (RDX) and 2,4,6-trinitrotoluene (TNT) in ground water at varying concentrations, with all detected HMX concentrations below the USEPA guideline for drinking water of 400 microg L(-1). An HMX mass balance on a transect perpendicular to ground water flow, about 300 m downgradient of the impact area, indicated an HMX flux of about 3 g d(-1) (0.7-1 kg yr(-1), 2005). The HMX mass in the impact area on the sand terrace was estimated at 7 to 10 kg (in 2005). The annual dissolved HMX flux represents about 10% of the source. The dissolved HMX plume in ground water consisted of a series of slugs, generated at each significant infiltration event. HMX is weakly retarded by sorption and is neither biotransformed nor mineralized under the aerobic conditions of the aquifer. TNT and RDX exceeded the USEPA guideline (2 microg L(-1) RDX and 1 microg L(-1) TNT) in three and two samples, respectively. The TNT plume was discontinuous because this compound was not always present at the ground surface. TNT is biotransformed, weakly sorbed, and not mineralized. In two wells, perchlorate associated with the propellant was found at concentrations above the Health Canada preliminary guideline of 6 microg L(-1) near the firing position.

Modeling the movement of a pH perturbation and its impact on adsorbed zinc and phosphate in a wastewater‐contaminated aquifer

USGS Publications Warehouse

Kent, D.B.; Wilkie, J.A.; Davis, J.A.

2007-01-01

Chemical conditions were perturbed in an aquifer with an ambient pH of 5.9 and wastewater‐derived adsorbed zinc (Zn) and phosphate (P) contamination by injecting a pulse of amended groundwater. The injected groundwater had low concentrations of dissolved Zn and P, a pH value of 4.5 resulting from equilibration with carbon dioxide gas, and added potassium bromide (KBr). Downgradient of the injection, breakthrough of nonreactive Br and total dissolved carbonate concentrations in excess of ambient values (excess TCO2) were accompanied by a decrease in pH values and over twentyfold increases in dissolved Zn concentrations above preinjection values. Peak concentrations of Br and excess TCO2 were followed by slow increases in pH values accompanied by significant increases in dissolved P above preinjection concentrations. The injected tracers mobilized a significant mass of wastewater‐derived Zn. Reactive transport simulations incorporating surface complexation models for adsorption of Zn, P, hydrogen ions, and major cations onto the aquifer sediments, calibrated using laboratory experimental data, captured most of the important trends observed during the experiment. These include increases in Zn concentrations in response to the pH perturbation, perturbations in major cation concentrations, attenuation of the pH perturbation with transport distance, and increases in alkalinity with transport distance. Observed desorption of P in response to chemical perturbations was not predicted, possibly because of a disparity between the range of chemical conditions in the calibration data set and those encountered during the field experiment. Zinc and P desorbed rapidly in response to changing chemical conditions despite decades of contact with the sediments. Surface complexation models with relatively few parameters in the form of logK values and site concentrations show considerable promise for describing the influence of variable chemistry on the transport of adsorbing contaminants.

Geochemistry and hydrology of a calcareous fen within the Savage Fen wetlands complex, Minnesota, USA

USGS Publications Warehouse

Komor, S.C.

1994-01-01

Savage Fen is a wetlands complex at the base of north-facing bluffs in the Minnesota River Valley. The complex includes 27.8 hectares of calcareous fen that host rare calciphile plants whose populations are declining in Minnesota. Water and sediment compositions in the calcareous fen were studied to gain a better understanding of the hydrologie System that sustains the rare vegetation. Groundwater in the fen is a calcium-magnesium-bicarbonate type with circumneutral pH values. The groundwater composition is the resuit of interactions among water, dissolved and gaseous carbon species, carbonates, and ion exchangers. Shallow groundwater is distinguished from deep groundwater by smaller concentrations of chloride, sulfate, magnesium, and sodium, and larger concentrations of calcium, bicarbonate, hydrogen sulfide, and ammonium. Magnesian calcite is the prevalent carbonate in unconsolidated sedimentary fill beneath the fen and is an important source and sink for dissolved calcium, magnesium, and inorganic carbon. Calcite concentrations just below the water table are small because aerobic and anaerobic oxidation of organic matter increase the partial pressure of carbon dioxide (PCO2), decrease pH, and cause calcite to dissolve. Thick calcite accumulations just above the water table, in the root zone of calciphile plants, result from water table fluctuations and attendant changes in PCO2. Groundwater beneath Savage Fen recharges in lakes and ponds south of the fen and upwells to the surface within the fen. Water at the water table is a mixture of upwelling groundwater and water near the surface that flows downslope from higher elevations in the fen. Changes in oxygen and hydrogen isotope compositions of shallow groundwater indicate that the proportion of upwelling groundwater in shallow groundwater decreases downgradient in the calcareous fen. Encroachment of reed grasses into the calcareous fen may reflect human-caused disturbances in the recharge area.

Assessment of Drywells as Effective Tools for Stormwater Management and Aquifer Recharge: Results of a Two-Year Field and Numerical Modeling Study

NASA Astrophysics Data System (ADS)

Edwards, E.; Washburn, B.; Harter, T.; Fogg, G. E.; Nelson, C.; Lock, B.; Li, X.

2016-12-01

Drywells are gravity-fed, excavated pits with perforated casings used to facilitate stormwater infiltration and groundwater recharge in areas with low permeability soils or cover. Stormwater runoff that would otherwise be routed to streams or drains in urban areas can be used as a source of aquifer recharge, potentially mitigating the effects of drought and harm to natural water bodies. However, the potential for groundwater contamination caused by urban runoff bypassing surface soil and near surface sediment attenuation processes has prevented more widespread use of drywells as a recharge mechanism. A field study was conducted in Elk Grove, CA, to determine the effects of drywell-induced stormwater infiltration on the local hydrogeologic system. Two drywells 13.5 meters in depth were constructed for the project: one in a preexisting drainage basin fed by residential lots, and one at an industrial site. Both sites were outfitted with vegetated pretreatments, and upgradient and downgradient groundwater monitoring wells. Site stormwater and groundwater were sampled between November, 2014, and May, 2016, and analyzed for contaminants. Results of water quality sampling have been statistically analyzed for trends and used to determine the contaminants of interest and the concentrations of these contaminants in influent stormwater. The fate and transport of these contaminants have been simulated using a 1D variably saturated flow and transport model and site specific parameters to predict long-term effects of stormwater infiltration on the surrounding hydrogeologic system. The potential for remobilization of geogenic heavy metals from changes in subsurface hydrochemistry caused by drywell infiltration have also been assessed. The results of the field study and numerical modeling assessment indicate that the study's drywells do not pose a long-term threat to groundwater quality and may be an effective source of aquifer recharge and tool for urban stormwater management.

Recharge sources and residence times of groundwater as determined by geochemical tracers in the Mayfield Area, southwestern Idaho, 2011–12

USGS Publications Warehouse

Hopkins, Candice B.

2013-01-01

Parties proposing residential development in the area of Mayfield, Idaho are seeking a sustainable groundwater supply. During 2011–12, the U.S. Geological Survey, in cooperation with the Idaho Department of Water Resources, used geochemical tracers in the Mayfield area to evaluate sources of aquifer recharge and differences in groundwater residence time. Fourteen groundwater wells and one surface-water site were sampled for major ion chemistry, metals, stable isotopes, and age tracers; data collected from this study were used to evaluate the sources of groundwater recharge and groundwater residence times in the area. Major ion chemistry varied along a flow path between deeper wells, suggesting an upgradient source of dilute water, and a downgradient source of more concentrated water with the geochemical signature of the Idaho Batholith. Samples from shallow wells had elevated nutrient concentrations, a more positive oxygen-18 signature, and younger carbon-14 dates than deep wells, suggesting that recharge comes from young precipitation and surface-water infiltration. Samples from deep wells generally had higher concentrations of metals typical of geothermal waters, a more negative oxygen-18 signature, and older carbon-14 values than samples from shallow wells, suggesting that recharge comes from both infiltration of meteoric water and another source. The chemistry of groundwater sampled from deep wells is somewhat similar to the chemistry in geothermal waters, suggesting that geothermal water may be a source of recharge to this aquifer. Results of NETPATH mixing models suggest that geothermal water composes 1–23 percent of water in deep wells. Chlorofluorocarbons were detected in every sample, which indicates that all groundwater samples contain at least a component of young recharge, and that groundwater is derived from multiple recharge sources. Conclusions from this study can be used to further refine conceptual hydrological models of the area.

Nitrate Remediation of Soil and Groundwater Using Phytoremediation: Transfer of Nitrogen Containing Compounds from the Subsurface to Surface Vegetation

NASA Astrophysics Data System (ADS)

Nelson, Sheldon

2013-04-01

Nitrate Remediation of Soil and Groundwater Using Phytoremediation: Transfer of Nitrogen Containing Compounds from the Subsurface to Surface Vegetation Sheldon Nelson Chevron Energy Technology Company 6001 Bollinger Canyon Road San Ramon, California 94583 snne@chevron.com The basic concept of using a plant-based remedial approach (phytoremediation) for nitrogen containing compounds is the incorporation and transformation of the inorganic nitrogen from the soil and/or groundwater (nitrate, ammonium) into plant biomass, thereby removing the constituent from the subsurface. There is a general preference in many plants for the ammonium nitrogen form during the early growth stage, with the uptake and accumulation of nitrate often increasing as the plant matures. The synthesis process refers to the variety of biochemical mechanisms that use ammonium or nitrate compounds to primarily form plant proteins, and to a lesser extent other nitrogen containing organic compounds. The shallow soil at the former warehouse facility test site is impacted primarily by elevated concentrations of nitrate, with a minimal presence of ammonium. Dissolved nitrate (NO3-) is the primary dissolved nitrogen compound in on-site groundwater, historically reaching concentrations of 1000 mg/L. The initial phases of the project consisted of the installation of approximately 1750 trees, planted in 10-foot centers in the areas impacted by nitrate and ammonia in the shallow soil and groundwater. As of the most recent groundwater analytical data, dissolved nitrate reductions of 40% to 96% have been observed in monitor wells located both within, and immediately downgradient of the planted area. In summary, an evaluation of time series groundwater analytical data from the initial planted groves suggests that the trees are an effective means of transfering nitrogen compounds from the subsurface to overlying vegetation. The mechanism of concentration reduction may be the uptake of residual nitrate from the vadose zone, the direct uptake of dissolved constituent from the upper portion of the saturated zone/capillary fringe, or a combination of these two processes.

Influence of citric acid on the surface texture of glass ionomer restorative materials

PubMed Central

Reddy, Dappili Swami Ranga; Kumar, Ramachandran Anil; Venkatesan, Sokkalingam Mothilal; Narayan, Gopal Shankar; Duraivel, Dasarathan; Indra, Rajamani

2014-01-01

Aim: This study determined the effectiveness of G-coat plus surface protective agent over petroleum jelly on the surface texture of conventional Glass ionomer restorative materials. Materials and Methods: Three chemically cured conventional glass ionomer restorative materials type II, type IX and ketac molar were evaluated in this study. Sixty specimens were made for each restorative material. They were divided into two groups of thirty specimens each. Of the sixty specimens, thirty were coated with G-coat plus (a nano-filler coating) and the rest with petroleum jelly. Thirty samples of both protective coating agents were randomly divided into six groups of five specimens and conditioned in citric acid solutions of differing pH (pH 2, 3, 4, 5, 6 & 7). Each specimen was kept in citric acid for three hours a day, and the rest of time stored in salivary substitute. This procedure was repeated for 8 days. After conditioning, the surface roughness (Ra, μm) of each specimen was measured using a surface profilometer (Taylor & Habson, UK). Data was analyzed using one-way analysis of variance (ANOVA) and Tukey's HSD test at a significance level of 0.05. Results: The surface textures of all the tested glass ionomer restorative materials protected with G-coat plus were not significantly affected by acids at low pH. The surface textures of all the tested glass ionomer restorative materials protected with petroleum jelly coating were significantly affected by acids at low pH. Conclusion: The effects of pH on the surface texture of glass ionomer restoratives are material dependent. Among all the materials tested the surface texture of Type II GIC (Group I) revealed marked deterioration when conditioned in solutions of low pH and was statistically significant. Hence, a protective coating either with G-coat plus or with light polymerized low viscosity unfilled resin adhesives is mandatory for all the glass ionomer restorations to increase the wear resistance of the restorative materials. PMID:25298643

Influence of citric acid on the surface texture of glass ionomer restorative materials.

PubMed

Reddy, Dappili Swami Ranga; Kumar, Ramachandran Anil; Venkatesan, Sokkalingam Mothilal; Narayan, Gopal Shankar; Duraivel, Dasarathan; Indra, Rajamani

2014-09-01

This study determined the effectiveness of G-coat plus surface protective agent over petroleum jelly on the surface texture of conventional Glass ionomer restorative materials. Three chemically cured conventional glass ionomer restorative materials type II, type IX and ketac molar were evaluated in this study. Sixty specimens were made for each restorative material. They were divided into two groups of thirty specimens each. Of the sixty specimens, thirty were coated with G-coat plus (a nano-filler coating) and the rest with petroleum jelly. Thirty samples of both protective coating agents were randomly divided into six groups of five specimens and conditioned in citric acid solutions of differing pH (pH 2, 3, 4, 5, 6 & 7). Each specimen was kept in citric acid for three hours a day, and the rest of time stored in salivary substitute. This procedure was repeated for 8 days. After conditioning, the surface roughness (Ra, μm) of each specimen was measured using a surface profilometer (Taylor & Habson, UK). Data was analyzed using one-way analysis of variance (ANOVA) and Tukey's HSD test at a significance level of 0.05. The surface textures of all the tested glass ionomer restorative materials protected with G-coat plus were not significantly affected by acids at low pH. The surface textures of all the tested glass ionomer restorative materials protected with petroleum jelly coating were significantly affected by acids at low pH. The effects of pH on the surface texture of glass ionomer restoratives are material dependent. Among all the materials tested the surface texture of Type II GIC (Group I) revealed marked deterioration when conditioned in solutions of low pH and was statistically significant. Hence, a protective coating either with G-coat plus or with light polymerized low viscosity unfilled resin adhesives is mandatory for all the glass ionomer restorations to increase the wear resistance of the restorative materials.

40 CFR 503.20 - Applicability.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SEWAGE SLUDGE STANDARDS FOR THE USE OR DISPOSAL OF SEWAGE SLUDGE Surface Disposal § 503.20 Applicability. (a) This subpart applies to any person who prepares sewage sludge that is placed on a surface disposal site, to the owner/operator of a...

30 CFR 865.11 - Protected activity.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 30 Mineral Resources 3 2013-07-01 2013-07-01 false Protected activity. 865.11 Section 865.11 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROTECTION OF EMPLOYEES PROTECTION OF EMPLOYEES § 865.11 Protected activity. (a) No person shall discharge or...

30 CFR 865.11 - Protected activity.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 3 2011-07-01 2011-07-01 false Protected activity. 865.11 Section 865.11 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROTECTION OF EMPLOYEES PROTECTION OF EMPLOYEES § 865.11 Protected activity. (a) No person shall discharge or...

30 CFR 865.11 - Protected activity.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 30 Mineral Resources 3 2012-07-01 2012-07-01 false Protected activity. 865.11 Section 865.11 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROTECTION OF EMPLOYEES PROTECTION OF EMPLOYEES § 865.11 Protected activity. (a) No person shall discharge or...

30 CFR 865.11 - Protected activity.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 30 Mineral Resources 3 2014-07-01 2014-07-01 false Protected activity. 865.11 Section 865.11 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROTECTION OF EMPLOYEES PROTECTION OF EMPLOYEES § 865.11 Protected activity. (a) No person shall discharge or...

30 CFR 865.11 - Protected activity.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Protected activity. 865.11 Section 865.11 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROTECTION OF EMPLOYEES PROTECTION OF EMPLOYEES § 865.11 Protected activity. (a) No person shall discharge or...

Water resources of the Keweenaw Bay Indian Community, Baraga County, Michigan

USGS Publications Warehouse

Sweat, M.J.; Rheaume, S.J.

1998-01-01

The Keweenaw Bay Indian Community (KBIC) in Baraga County uses ground water for most domestic, commercial, and industrial supplies. An industrial park within KBIC could adversely affect some ground-water supplies should contaminants be spilled at the park. Additional development of the park is being planned. Information on water supply potential and aquifer vulnerability to contamination is needed to make sound decisions about future activities at the industrial park. Unconsolidated glacial deposits overlie bedrock within the Keweenaw Bay Indian Community. Usable amounts of ground water are withdrawn from the glacial deposits only in isolated areas. Principal aquifers are the Jacobsville Sandstone and the Michigamme Slate. Aquifer test and water level data from these principal aquifers indicate that they are confined and hydraulically connected throughout most of KBIC. Ground water generally flows toward Keweenaw and Huron Bays and the Silver River. Between the industrial park and Keweenaw Bay, ground water flows to the southeast, toward the Bay. Along this flow path in the bedrock, glacial deposits are generally thicker than 25 meters, and contain thick lenses of clay and clay mixed with sand. The average depth to ground water along this flow path is greater than 25 meters, indicating unconfined conditions. Near the shore of Keweenaw and Huron Bays, however, and at isolated areas throughout KBIC, water levels in wells are above land surface. Analyses of water samples collected in 1991 and 1997 indicate that the quality of ground water and surface water is suitable for most domestic, commercial, and industrial uses. However, U.S. Environmental Protection Agency secondary maximum contaminant limits for dissolved iron and manganese were exceeded in 4 and 5 wells, respectively, which may make the water from these wells unsuitable for some uses. Concentrations of lead in water from one well was above the maximum contaminant limit. Concentrations of tritium in ground water downgradient from the industrial park indicate that at least some recharge to the Jacobsville Sandstone has taken place within the last 45 years. Where clay lenses greater than 1 meter thick overlie the glacial aquifer or the Jacobsville Sandstone, however, recharge may take longer than 45 years. A contaminant spill at the industrial park would likely move laterally, toward Keweenaw Bay, in the glacial aquifer. Some infiltration does occur through the glacial aquifer to the bedrock aquifers. No information is available concerning the rate of movement of water within this aquifer, so it is not possible to determine the rate at which a spill would move either vertically or laterally within the glacial aquifer toward either Keweenaw Bay or the Jacobsville Sandstone. Increased pumping from the existing well at the industrial park, or the development of additional wells, could potentially lower water levels in the Jacobsville Sandstone in the area of the park. Sufficient lowering of water levels could create unconfined conditions in the Jacobsville Sandstone, thereby increasing the susceptability of the aquifer to contamination.

Semiconductor surface protection material

NASA Technical Reports Server (NTRS)

Packard, R. D. (Inventor)

1973-01-01

A method and a product for protecting semiconductor surfaces is disclosed. The protective coating material is prepared by heating a suitable protective resin with an organic solvent which is solid at room temperature and converting the resulting solution into sheets by a conventional casting operation. Pieces of such sheets of suitable shape and thickness are placed on the semiconductor areas to be coated and heat and vacuum are then applied to melt the sheet and to drive off the solvent and cure the resin. A uniform adherent coating, free of bubbles and other defects, is thus obtained exactly where it is desired.

A ceramic matrix composite thermal protection system for hypersonic vehicles

NASA Technical Reports Server (NTRS)

Riccitiello, Salvatore R.; Love, Wendell L.; Pitts, William C.

1993-01-01

The next generation of hypersonic vehicles (NASP, SSTO) that require reusable thermal protection systems will experience acreage surface temperatures in excess of 1100 C. More important, they will experience a more severe physical environment than the Space Shuttle due to non-pristine launching and landing conditions. As a result, maintenance, inspection, and replacement factors must be more thoroughly incorporated into the design of the TPS. To meet these requirements, an advanced thermal protection system was conceived, designated 'TOPHAT'. This system consists of a toughened outer ceramic matrix composite (CMC) attached to a rigid reusable surface insulator (RSI) which is directly bonded to the surface. The objective of this effort was to evaluate this concept in an aeroconvective environment, to determine the effect of impacts to the CMC material, and to compare the results with existing thermal protection systems.

Chitosan-based ultrathin films as antifouling, anticoagulant and antibacterial protective coatings.

PubMed

Bulwan, Maria; Wójcik, Kinga; Zapotoczny, Szczepan; Nowakowska, Maria

2012-01-01

Ultrathin antifouling and antibacterial protective nanocoatings were prepared from ionic derivatives of chitosan using layer-by-layer deposition methodology. The surfaces of silicon, and glass protected by these nanocoatings were resistant to non-specific adsorption of proteins disregarding their net charges at physiological conditions (positively charged TGF-β1 growth factor and negatively charged bovine serum albumin) as well as human plasma components. The coatings also preserved surfaces from the formation of bacterial (Staphylococcus aureus) biofilm as shown using microscopic studies (SEM, AFM) and the MTT viability test. Moreover, the chitosan-based films adsorbed onto glass surface demonstrated the anticoagulant activity towards the human blood. The antifouling and antibacterial actions of the coatings were correlated with their physicochemical properties. The studied biologically relevant properties were also found to be dependent on the thickness of those nanocoatings. These materials are promising for biomedical applications, e.g., as protective coatings for medical devices, anticoagulant coatings and protective layers in membranes.

40 CFR 761.280 - Application and scope.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 761.280 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL... Remediation Waste and Porous Surfaces in Accordance With § 761.61(a)(6) § 761.280 Application and scope...-implementing, on-site disposal of bulk PCB remediation waste and porous surfaces consistent with the levels of...

40 CFR 761.280 - Application and scope.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 761.280 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL... Remediation Waste and Porous Surfaces in Accordance With § 761.61(a)(6) § 761.280 Application and scope...-implementing, on-site disposal of bulk PCB remediation waste and porous surfaces consistent with the levels of...

40 CFR 761.280 - Application and scope.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 761.280 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL... Remediation Waste and Porous Surfaces in Accordance With § 761.61(a)(6) § 761.280 Application and scope...-implementing, on-site disposal of bulk PCB remediation waste and porous surfaces consistent with the levels of...

40 CFR 761.280 - Application and scope.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 761.280 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL... Remediation Waste and Porous Surfaces in Accordance With § 761.61(a)(6) § 761.280 Application and scope...-implementing, on-site disposal of bulk PCB remediation waste and porous surfaces consistent with the levels of...

76 FR 13567 - Approval and Promulgation of Air Quality Implementation Plans; Pennsylvania; Adoption of Control...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-03-14

... Flat Wood Paneling Surface Coating Processes AGENCY: Environmental Protection Agency (EPA). ACTION... sources covered by EPA's Control Techniques Guidelines (CTG) standards for flat wood paneling surface... Protection (PADEP) submitted to EPA a SIP revision concerning the adoption of the CTG for flat wood paneling...

Layer Protecting the Surface of Zirconium Used in Nuclear Reactors.

PubMed

Ashcheulov, Petr; Skoda, Radek; Skarohlíd, Jan; Taylor, Andrew; Fendrych, Frantisek; Kratochvílová, Irena

2016-01-01

Zirconium alloys have very useful properties for nuclear facilities applications having low absorption cross-section of thermal electrons, high ductility, hardness and corrosion resistance. However, there is also a significant disadvantage: it reacts with water steam and during this (oxidative) reaction it releases hydrogen gas, which partly diffuses into the alloy forming zirconium hydrides. A new strategy for surface protection of zirconium alloys against undesirable oxidation in nuclear reactors by polycrystalline diamond film has been patented- Czech patent 305059: Layer protecting the surface of zirconium alloys used in nuclear reactors and PCT patent: Layer for protecting surface of zirconium alloys (Patent Number: WO2015039636-A1). The zirconium alloy surface was covered by polycrystalline diamond layer grown in plasma enhanced chemical vapor deposition apparatus with linear antenna delivery system. Substantial progress in the description and understanding of the polycrystalline diamond/ zirconium alloys interface and material properties under standard and nuclear reactors conditions (irradiation, hot steam oxidation experiments and heating-quenching cycles) was made. In addition, process technology for the deposition of protective polycrystalline diamond films onto the surface of zirconium alloys was optimized. Zircaloy2 nuclear fuel pins were covered by 300 nm thick protective polycrystalline diamond layer (PCD) using plasma enhanced chemical vapor deposition apparatus with linear antenna delivery system. The polycrystalline diamond layer protects the zirconium alloy surface against undesirable oxidation and consolidates its chemical stability while preserving its functionality. PCD covered Zircaloy2 and standard Zircaloy2 pins were for 30 min. oxidized in 1100°C hot steam. Under these conditions α phase of zirconium changes to β phase (more opened for oxygen/hydrogen diffusion). PCD anticorrosion protection of Zircaloy nuclear fuel assemblies can significantly prolong lifetime of Zirconium alloy in nuclear reactors even above Zirconium phase transition temperatures. Even after ion beam irradiation (10 dpa, 3 MeV Fe(2+)) the diamond film still shows satisfactory structural integrity with both sp(3) and sp(2) carbon phases. Zircaloy2 under the carbon-based protective layer after hot steam oxidation test differed from the original Zircaloy2 material composition only very slightly, proving that the diamond coating increases the material resistance to high temperature oxidation. Zirconium alloys nuclear fuel pins' surfaces were covered by compact and homogeneous polycrystalline diamond layers consisting of sp(3) and sp(2) carbon phases with a high crystalline diamond content and low roughness. Diamond withstands very high temperatures, has excellent thermal conductivity and low chemical reactivity, it does not degrade over time and (important for the nuclear fuel cladding) being pure carbon, it has perfect neutron cross-section properties. Moreover, polycrystalline diamond layers consisting of crystalline (sp(3)) and amorphous (sp(2)) carbon phases could have suitable thermal expansion. Zirconium alloys coated with polycrystalline diamond film are protected against undesirable changes and processes. Further, the polycrystalline diamond layer prevents the reaction between the alloy surface and water vapor. During such reaction, water molecules dissociate and initiate formation of zirconium dioxide and hydrogen, accompanied by the release of large amount of heat. Thus the protective layer prevents the formation of hydrogen and the release of reaction heat. Few relevant patents to the topic have been reviewed and cited.

An evaluation of candidate oxidation resistant materials for space applications in LEO

NASA Technical Reports Server (NTRS)

Rutledge, Sharon; Banks, Bruce; Difilippo, Frank; Brady, Joyce; Dever, Therese; Hotes, Deborah

1986-01-01

Ground based testing of materials considered for polyimide (Kapton) solar array blanket protection and graphite-epoxy stroctural member protection was performed in an RF plasma asher. Protective coatings on Kapton from various commercial sources and from NASA Lewis Research Center were exposed to the air plasma; and mass loss per unit area was measured for each sample. All samples evaluated provided some protection to the underlying surface, but metal-oxide-fluoropolymer coatings provided the best protection by exhibiting very little degradation after 47 hr of asher exposure. Mica paint was evaluated as a protective coating for graphite-epoxy structural members. Mica appeared to be resistant to attack by atomic oxygen, but only offered limited protection as a paint. this is believed to be due to the paint vehicle ashing underneath the mica leaving unattached mica flakes lying on the surface. The protective coatings on Kapton evaluated so far are promising but further research on protection of graphite-epoxy support structures is needed.

Hubble Space Telescope servicing mission scientific instrument protective enclosure design requirements and contamination controls

NASA Technical Reports Server (NTRS)

Hansen, Patricia A.; Hughes, David W.; Hedgeland, Randy J.; Chivatero, Craig J.; Studer, Robert J.; Kostos, Peter J.

1994-01-01

The Scientific Instrument Protective Enclosures were designed for the Hubble Space Telescope Servicing Missions to provide a beginning environment to a Scientific Instrument during ground and on orbit activities. The Scientific Instruments required very stringent surface cleanliness and molecular outgassing levels to maintain ultraviolet performance. Data from the First Servicing Mission verified that both the Scientific Instruments and Scientific Instrument Protective Enclosures met surface cleanliness level requirements during ground and on-orbit activities.

Significant Association between Sulfate-Reducing Bacteria and Uranium-Reducing Microbial Communities as Revealed by a Combined Massively Parallel Sequencing-Indicator Species Approach▿ †

PubMed Central

Cardenas, Erick; Wu, Wei-Min; Leigh, Mary Beth; Carley, Jack; Carroll, Sue; Gentry, Terry; Luo, Jian; Watson, David; Gu, Baohua; Ginder-Vogel, Matthew; Kitanidis, Peter K.; Jardine, Philip M.; Zhou, Jizhong; Criddle, Craig S.; Marsh, Terence L.; Tiedje, James M.

2010-01-01

Massively parallel sequencing has provided a more affordable and high-throughput method to study microbial communities, although it has mostly been used in an exploratory fashion. We combined pyrosequencing with a strict indicator species statistical analysis to test if bacteria specifically responded to ethanol injection that successfully promoted dissimilatory uranium(VI) reduction in the subsurface of a uranium contamination plume at the Oak Ridge Field Research Center in Tennessee. Remediation was achieved with a hydraulic flow control consisting of an inner loop, where ethanol was injected, and an outer loop for flow-field protection. This strategy reduced uranium concentrations in groundwater to levels below 0.126 μM and created geochemical gradients in electron donors from the inner-loop injection well toward the outer loop and downgradient flow path. Our analysis with 15 sediment samples from the entire test area found significant indicator species that showed a high degree of adaptation to the three different hydrochemical-created conditions. Castellaniella and Rhodanobacter characterized areas with low pH, heavy metals, and low bioactivity, while sulfate-, Fe(III)-, and U(VI)-reducing bacteria (Desulfovibrio, Anaeromyxobacter, and Desulfosporosinus) were indicators of areas where U(VI) reduction occurred. The abundance of these bacteria, as well as the Fe(III) and U(VI) reducer Geobacter, correlated with the hydraulic connectivity to the substrate injection site, suggesting that the selected populations were a direct response to electron donor addition by the groundwater flow path. A false-discovery-rate approach was implemented to discard false-positive results by chance, given the large amount of data compared. PMID:20729318

Significant association between sulfate-reducing bacteria and uranium-reducing microbial communities as revealed by a combined massively parallel sequencing-indicator species approach.

PubMed

Cardenas, Erick; Wu, Wei-Min; Leigh, Mary Beth; Carley, Jack; Carroll, Sue; Gentry, Terry; Luo, Jian; Watson, David; Gu, Baohua; Ginder-Vogel, Matthew; Kitanidis, Peter K; Jardine, Philip M; Zhou, Jizhong; Criddle, Craig S; Marsh, Terence L; Tiedje, James M

2010-10-01

Massively parallel sequencing has provided a more affordable and high-throughput method to study microbial communities, although it has mostly been used in an exploratory fashion. We combined pyrosequencing with a strict indicator species statistical analysis to test if bacteria specifically responded to ethanol injection that successfully promoted dissimilatory uranium(VI) reduction in the subsurface of a uranium contamination plume at the Oak Ridge Field Research Center in Tennessee. Remediation was achieved with a hydraulic flow control consisting of an inner loop, where ethanol was injected, and an outer loop for flow-field protection. This strategy reduced uranium concentrations in groundwater to levels below 0.126 μM and created geochemical gradients in electron donors from the inner-loop injection well toward the outer loop and downgradient flow path. Our analysis with 15 sediment samples from the entire test area found significant indicator species that showed a high degree of adaptation to the three different hydrochemical-created conditions. Castellaniella and Rhodanobacter characterized areas with low pH, heavy metals, and low bioactivity, while sulfate-, Fe(III)-, and U(VI)-reducing bacteria (Desulfovibrio, Anaeromyxobacter, and Desulfosporosinus) were indicators of areas where U(VI) reduction occurred. The abundance of these bacteria, as well as the Fe(III) and U(VI) reducer Geobacter, correlated with the hydraulic connectivity to the substrate injection site, suggesting that the selected populations were a direct response to electron donor addition by the groundwater flow path. A false-discovery-rate approach was implemented to discard false-positive results by chance, given the large amount of data compared.

Contamination of shallow ground water in the area of building 95, Picatinny Arsenal, New Jersey, 1985-90

USGS Publications Warehouse

Sargent, B.P.; Storck, D.A.

1994-01-01

A zone of contaminated ground water at Picatinny Arsenal has resulted from the operation of a metal- plating facility in building 95 during 1960-81, and the wastewater-treatment system that is in and adjacent to the building. Thirty-two monitoring wells were installed in 1989 to supplement 12 previously installed wells. All wells were sampled in 1989 and 1990 for analysis of ground water for inorganic constituents, trace elements, volatile organic compounds, and nutrients. Four wells also were sampled for analysis for base/neutral- and acid-extractable compounds and pesticides, and soil gas from the unsaturated zone at eight sites was analyzed for volatile organic compounds. Concentrations of dissolved solids and sulfate in the study area were consistently above the U.S. Environmental Protection Agency's secondary drinking-water regulations. The areal distribution of sulfate differed from that of the volatile organic compounds. Concentrations of trace elements were not elevated downgradient from the source. The estimated average velocity of contaminant movement is 0.1 to 1.1 feet per day. The major organic contaminants identified in the study area are trichloroethylene, tetrachloroethylene, and 1,1,1-trichloroethane. Trichloroethylene was detected in wells upgradient from the wastewater- treatment site. Tetrachloroethylene and 1,1,1-trichloroethane might originate at tanks in the basement of building 95 rather than at the adjacent wastewater-treatment system. The pre- dominant gas-phase contaminant, 1,1,1- trichloroethane, was detected at a maximum con- centration of 15.7 micrograms per liter. Both trichoroethylene and tetrachloroethylene were detected in concentrations greater than 0.10 micrograms per liter in five of the eight soil- gas samples, indicating that volatilization and diffusion through the unsaturated zone could be a significant mechanism of contaminant loss from the aquifer.

GROUDWATER REMEDIATION AT THE 100-HR-3 OPERABLE UNIT HANFORD SITE WASHINGTON USA - 11507

DOE Office of Scientific and Technical Information (OSTI.GOV)

SMOOT JL; BIEBESHEIMER FH; ELUSKIE JA

2011-01-12

The 100-HR-3 Groundwater Operable Unit (OU) at the Hanford Site underlies three former plutonium production reactors and the associated infrastructure at the 100-D and 100-H Areas. The primary contaminant of concern at the site is hexavalent chromium; the secondary contaminants are strontium-90, technetium-99, tritium, uranium, and nitrate. The hexavalent chromium plume is the largest plume of its type in the state of Washington, covering an area of approximately 7 km{sup 2} (2.7 mi{sup 2}) with concentrations greater than 20 {micro}g/L. Concentrations range from 60,000 {micro}g/L near the former dichromate transfer station in the 100-D Area to large areas of 20more » to 100 {micro}g/L across much of the plume area. Pump-and-treat operations began in 1997 and continued into 2010 at a limited scale of approximately 200 gal/min. Remediation of groundwater has been fairly successful in reaching remedial action objectives (RAOs) of 20 {micro}g/L over a limited region at the 100-H, but less effective at 100-D. In 2000, an in situ, permeable reactive barrier was installed downgradient of the hotspot in 100-D as a second remedy. The RAOs are still being exceeded over a large portion of the area. The CH2M HILL Plateau Remediation Company was awarded the remediation contract for groundwater in 2008 and initiated a remedial process optimization study consisting of modeling and technical studies intended to enhance the remediation. As a result of the study, 1,400 gal/min of expanded treatment capacity are being implemented. These new systems are designed to meet 2012 and 2020 target milestones for protection of the Columbia River and cleanup of the groundwater plumes.« less

Assessing Protection Afforded to the Microbiological Quality of Bedrock Groundwater from the Impacts of Septic Tank Effluent by Irish Glacial Till: A Field Study

NASA Astrophysics Data System (ADS)

Orr, Alison; McCarthy, Valerie; Meehan, Robert; Flynn, Raymond

2010-05-01

The rural population of Ireland relies almost exclusively on on-site treatment systems for disposal of waste water. Septic tank systems, which discharge effluent to ground, constitute the dominant means of waste water disposal. Many of the areas that employ this technology rely on private or small group groundwater supplies, often located in close proximity of septic tanks. Since many of these water supplies provide raw groundwater to consumers, septic tank effluent (STE) can pose a significant hazard to the microbiological quality of drinking water. T-tests (infiltration testing) carried out prior to tank installation aim to assess the capacity of subsoils to receive STE. Tests completed across Ireland indicate that many existing septic tank systems are located in low permeability subsoils. These subsoils are assumed to afford significant protection to the microbiological quality of groundwater in the underlying bedrock units. A two year investigation in the Lough Muckno Catchment in Co. Monaghan, investigating the impact of STE on water quality, involved carrying out T-tests at three sites where effluent discharged to a dense, silty, ‘fractured' glacial till derived from the underlying bedrock and containing clasts of low grade metamorphic Ordovician and Silurian sandstone and shale. Analysis of groundwater samples collected from 28 piezometers straddling the water table within the till, down-gradient of septic tank systems at two sites, permitted faecal indicator microorganism (FIO) levels in near-surface groundwater to be established. Associated hydraulic conductivity tests (slug tests) at all three sites permitted an evaluation of the levels of horizontal hydraulic conductivity heterogeneity present in the till. Slug test results suggest that till median hydraulic conductivities range from 1.1x10-4 cm/s to 1.1x10-5 cm/s, with variability of up to 2 orders of magnitude across each site. On the other hand no significant differences in properties existed between sites. T-test results ranged from 37.96 min/25mm to 98.26 min/25mm, suggesting hydraulic conductivities of the order of 1.1x10-3 cm/s to 4.24x10-4 cm/s. The contrast in hydraulic conductivity between T-test and slug test results may reflect slight anisotropy within the till, with water flowing vertically a little more easily than horizontally, under equivalent gradients. Despite the low hydraulic conductivities and the low hydraulic gradients observed at each site, analyses of water samples collected from up to 115 metres from septic tank discharge points consistently detected FIOs. The results of the study highlight the possibility of viable pathogenic microorganisms being transported considerable distances from septic tanks through fine-grained glacial tills. Given limited survival times of FIOs outside of their host organisms, study findings suggest that travel times in the till separating septic tanks from monitoring points are of the order of 10s of days, despite similarly low hydraulic conductivities determined independently by the T-test and slug test methods. The microbiological results, coupled to hydraulic measurements, point to very low effective porosities in the till that may possibly relate to fracturing. Moreover, hydraulic conductivity anisotropy suggests that contaminants may flow equally easily to depth. However, the exact levels of protection provided by the till will be a function of effective porosity variation with depth; the role played by fractures remains to be investigated but could prove to be potentially significant. Overall, the results of the study suggest that the levels of protection afforded by fine-grained Irish tills to bedrock aquifers may be considerably lower than originally assumed.

Erosion-protecting effect of oral-care products available on the Swiss market. A pilot study

PubMed

Wasser, Gregor; João-Souza, Samira H; Lussi, Adrian; Carvalho, Thiago S

2018-03-28

The present study sought to test oral-care products available on the Swiss market, such as toothpastes and gels, with respect to the protection of enamel against erosive tooth wear. A total of 56 enamel specimens were divided into 7 groups (n = 8): F-TP = Migros Budget Anti-Caries Toothpaste (Negative Control); F+Sn3500-TP = Elmex Erosion Protection Toothpaste (Positive Control); F-TP + F+Oligopep-Gel = Migros Budget Anti-Caries Toothpaste + Emofluor Protect Gel Professional; F+Sn3120-Gel = Emofluor Gel Intensive Care; F+Oligopep-TP = Candida Protect Professional Toothpaste; F+Sn1260-TP = Emoform-F Protect Toothpaste; and F+Sn3440-TP = Sensodyne Repair & Protect Toothpaste. The specimens were incubated in artificial saliva for 30 min and then brushed in a toothbrushing machine (10 s brushing; total 2 min exposure to the product). After the toothbrush abrasion, the specimens were rinsed, dried and submitted to an erosive challenge (2 min; 1% citric acid; pH 3.6). This sequence was repeated 4 times, and the total enamel surface loss was calculated using indentation measurements before and after the brushing period. All groups presented progressive surface loss throughout the experiment; after 4 cycles, total surface loss values ranged from 0.11 µm (F+Sn3120-Gel) to 0.89 µm (F+Sn1260-TP). Regarding the total surface loss values (median; interquartile range), F-TP (0.54; 0.42–0.59) presented no significant differences compared to any of the other groups. F+Sn3500-TP (0.33; 0.30–0.40), F-TP + F+Oligopep-Gel (0.34; 0.29–0.42) and F+Sn3120-Gel (0.11; 0.09–0.15) presented lower surface loss than F+Oligopep-TP (0.75; 0.59–0.98), F+Sn1260-TP (0.89; 0.68–1.13) and F+Sn3440-TP (0.69; 0.66–0.78). Conclusion: Although some of the oral-care products containing stannous ions or oligopeptide-104 presented numerically lower SL values, they did not present significantly better protection than a regular fluoride toothpaste. The gels showed a general trend of better enamel protection against ETW.

Formation of protective deposits by anti-erosive toothpastes-A microscopic study on enamel with artificial defects.

PubMed

Bradna, Pavel; Vrbova, Radka; Fialova, Vlasta; Housova, Devana; Gojisova, Eva

2016-09-01

This study investigated formation of protective deposits on the enamel surface after application of several anti-erosive toothpastes with different active ingredients. NaF-containing Sensodyne Pronamel, SnCl 2 /F-based Elmex Erosion Protection and calcium phosphate-based BioRepair Plus Sensitivity Control, SensiShield and Enamel Care toothpastes with claimed anti-erosive properties were tested. Artificial saliva and Elmex Erosion Protection mouth rinse served as control groups. The toothpastes were applied 30 times by a toothbrush for 2 min per day, mouth rinse for 30 s on polished enamel of thirty five human molars (n = 5) with series of five rhomboid-shaped indents of various length prepared by a Knoop indentor. After 15 and 30 applications, the shape of the indents and surface morphology was characterised using light and scanning electron microscopy. At the end of treatment, the samples were exposed to 0.2 wt. % citric acid (pH 3.30) to test resistance of the treated enamel to erosion. Pronounced differences were observed between protective properties of the toothpastes. While Sensodyne Pronamel and BioRepair Plus Sensitivity Control did not produce any protective deposits, Enamel Care formed a compact layer of deposits which protected the enamel surface against erosion. With Elmex Erosion Protection and SensiShield fractured indent edges and scratches on the treated enamel suggested that their abrasive properties prevailed over ability of active ingredients to form deposits. These results revealed that toothpastes with strong potential to form acid-resistant deposits on the enamel surface and of low abrasivity should be used for effective prevention of enamel erosion. SCANNING 38:380-388, 2016. © 2015 Wiley Periodicals, Inc. © Wiley Periodicals, Inc.

UV-blocking spectacle lens protects against UV-induced decline of visual performance.

PubMed

Liou, Jyh-Cheng; Teng, Mei-Ching; Tsai, Yun-Shan; Lin, En-Chieh; Chen, Bo-Yie

2015-01-01

Excessive exposure to sunlight may be a risk factor for ocular diseases and reduced visual performance. This study was designed to examine the ability of an ultraviolet (UV)-blocking spectacle lens to prevent visual acuity decline and ocular surface disorders in a mouse model of UVB-induced photokeratitis. Mice were divided into 4 groups (10 mice per group): (1) a blank control group (no exposure to UV radiation), (2) a UVB/no lens group (mice exposed to UVB rays, but without lens protection), (3) a UVB/UV400 group (mice exposed to UVB rays and protected using the CR-39™ spectacle lens [UV400 coating]), and (4) a UVB/photochromic group (mice exposed to UVB rays and protected using the CR-39™ spectacle lens [photochromic coating]). We investigated UVB-induced changes in visual acuity and in corneal smoothness, opacity, and lissamine green staining. We also evaluated the correlation between visual acuity decline and changes to the corneal surface parameters. Tissue sections were prepared and stained immunohistochemically to evaluate the structural integrity of the cornea and conjunctiva. In blank controls, the cornea remained undamaged, whereas in UVB-exposed mice, the corneal surface was disrupted; this disruption significantly correlated with a concomitant decline in visual acuity. Both the UVB/UV400 and UVB/photochromic groups had sharper visual acuity and a healthier corneal surface than the UVB/no lens group. Eyes in both protected groups also showed better corneal and conjunctival structural integrity than unprotected eyes. Furthermore, there were fewer apoptotic cells and less polymorphonuclear leukocyte infiltration in corneas protected by the spectacle lenses. The model established herein reliably determines the protective effect of UV-blocking ophthalmic biomaterials, because the in vivo protection against UV-induced ocular damage and visual acuity decline was easily defined.

40 CFR 265.223 - Containment system.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 27 2012-07-01 2012-07-01 false Containment system. 265.223 Section 265.223 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES (CONTINUED... FACILITIES Surface Impoundments § 265.223 Containment system. All earthen dikes must have a protective cover...

40 CFR 265.223 - Containment system.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 25 2010-07-01 2010-07-01 false Containment system. 265.223 Section 265.223 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES (CONTINUED... FACILITIES Surface Impoundments § 265.223 Containment system. All earthen dikes must have a protective cover...

Nanocomposite protective coatings for battery anodes

DOEpatents

Lemmon, John P; Xiao, Jie; Liu, Jun

2014-01-21

Modified surfaces on metal anodes for batteries can help resist formation of malfunction-inducing surface defects. The modification can include application of a protective nanocomposite coating that can inhibit formation of surface defects. such as dendrites, on the anode during charge/discharge cycles. For example, for anodes having a metal (M'), the protective coating can be characterized by products of chemical or electrochemical dissociation of a nanocomposite containing a polymer and an exfoliated compound (M.sub.a'M.sub.b''X.sub.c). The metal, M', comprises Li, Na, or Zn. The exfoliated compound comprises M' among lamella of M.sub.b''X.sub.c, wherein M'' is Fe, Mo, Ta, W, or V, and X is S, O, or Se.

Effect of Melt Temperature on Surface Films Formed on Molten AZ91D Alloy Protected by Graphite Powder

NASA Astrophysics Data System (ADS)

Li, Weihong; Zhou, Jixue; Ma, Baichang; Wang, Jinwei; Wu, Jianhua; Yang, Yuansheng

2017-12-01

Graphite powder was adopted to prevent AZ91D alloy from oxidizing during melting and casting. The microstructure of the resultant surface films, formed at 933 K, 973 K, 1013 K, and 1053 K (660 °C, 700 °C, 740 °C, and 780 °C) for 30 minutes, was investigated by scanning electron microscopy, energy dispersive spectrometer, and X-ray diffraction, and the phase composition of the surface films was analyzed by the standard Gibbs free energy change of the reactions between the graphite powder, the alloy melt, and the ambient atmosphere. The effect and mechanism of melt temperature on the resultant surface films were also discussed. The results indicated that the surface films, of which the surface morphology comprised folds and wrinkles, were composed of a protective layer and MgF2 particles. The protective layer was contributive to the prevention of the molten alloy from oxidizing, and consisted of magnesium, oxygen, fluorine, carbon, and a small amount of aluminium existing in the form of MgO, MgF2, C, and MgAl2O4. The layer thickness was 200 to 900 nm. The melt temperature may affect the surface films through the increased interaction between the graphite powder, the melt, and the ambient atmosphere. The oxygen content and thickness of the protective layer decreased and then increased, while the height of the folds increased with melt temperature.

Information processing capacity while wearing personal protective eyewear.

PubMed

Wade, Chip; Davis, Jerry; Marzilli, Thomas S; Weimar, Wendi H

2006-08-15

It is difficult to overemphasize the function vision plays in information processing, specifically in maintaining postural control. Vision appears to be an immediate, effortless event; suggesting that eyes need only to be open to employ the visual information provided by the environment. This study is focused on investigating the effect of Occupational Safety and Health Administration regulated personal protective eyewear (29 CFR 1910.133) on physiological and cognitive factors associated with information processing capabilities. Twenty-one college students between the ages of 19 and 25 years were randomly tested in each of three eyewear conditions (control, new and artificially aged) on an inclined and horizontal support surface for auditory and visual stimulus reaction time. Data collection trials consisted of 50 randomly selected (25 auditory, 25 visual) stimuli over a 10-min surface-eyewear condition trial. Auditory stimulus reaction time was significantly affected by the surface by eyewear interaction (F2,40 = 7.4; p < 0.05). Similarly, analysis revealed a significant surface by eyewear interaction in reaction time following the visual stimulus (F2,40 = 21.7; p < 0.05). The current findings do not trivialize the importance of personal protective eyewear usage in an occupational setting; rather, they suggest the value of future research focused on the effect that personal protective eyewear has on the physiological, cognitive and biomechanical contributions to postural control. These findings suggest that while personal protective eyewear may serve to protect an individual from eye injury, an individual's use of such personal protective eyewear may have deleterious effects on sensory information associated with information processing and postural control.

Electrocatalysis paradigm for protection of cathode materials in high-voltage lithium-ion batteries

DOE PAGES

Shkrob, Ilya A.; Abraham, Daniel P.

2016-07-06

A new mechanistic framework is suggested to account for the protective action of certain electrolyte additives on high-voltage positive electrode (cathode) materials. The mechanism involves inactivation of catalytically active centers on the electrode active materials through fragmentation reactions involving molecules at its surface. The cathode protection additives oxidize before the solvent and serve as sacrificial inhibitors of the catalytic centers. Without the additive, the surface oxidation of the solvent (like solvent oxidation in the bulk) yields H loss radicals and releases the proton that can combine with anions forming corrosive acids. This proton-release reaction is demonstrated experimentally for boronate additives.more » Specific radical reactions for the latter additives on the electrode surface are suggested. Furthermore, the same approach can be used to rationalize the protective action of other additives and account for various observations regarding their performance.« less

A ceramic matrix composite thermal protection system for hypersonic vehicles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Riccitiello, S.R.; Love, W.L.; Pitts, W.C.

1993-07-01

The next generation of hypersonic vehicles (NASP, SSTO) that require reusable thermal protection systems will experience acreage surface temperatures in excess of 1100 C. More important, they will experience a more severe physical environment than the Space Shuttle due to non-pristine launching and landing conditions. As a result, maintenance, inspection, and replacement factors must be more thoroughly incorporated into the design of the TPS. To meet these requirements, an advanced thermal protection system was conceived, designated 'TOPHAT'. This system consists of a toughened outer ceramic matrix composite (CMC) attached to a rigid reusable surface insulator (RSI) which is directly bondedmore » to the surface. The objective of this effort was to evaluate this concept in an aeroconvective environment, to determine the effect of impacts to the CMC material, and to compare the results with existing thermal protection systems. 10 refs.« less

Electrocatalysis paradigm for protection of cathode materials in high-voltage lithium-ion batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shkrob, Ilya A.; Abraham, Daniel P.

A new mechanistic framework is suggested to account for the protective action of certain electrolyte additives on high-voltage positive electrode (cathode) materials. The mechanism involves inactivation of catalytically active centers on the electrode active materials through fragmentation reactions involving molecules at its surface. The cathode protection additives oxidize before the solvent and serve as sacrificial inhibitors of the catalytic centers. Without the additive, the surface oxidation of the solvent (like solvent oxidation in the bulk) yields H loss radicals and releases the proton that can combine with anions forming corrosive acids. This proton-release reaction is demonstrated experimentally for boronate additives.more » Specific radical reactions for the latter additives on the electrode surface are suggested. Furthermore, the same approach can be used to rationalize the protective action of other additives and account for various observations regarding their performance.« less

Corrosion protective coating for metallic materials

DOEpatents

Buchheit, Rudolph G.; Martinez, Michael A.

1998-01-01

Corrosion protective coatings for metallic materials, particularly aluminum and aluminum alloys, produced with simple, low-cost equipment and materials other than toxic metals or metal salts, or metal cyanides. The metallic material is cleaned, degreased, and deoxidized, the surface is converted to a substantially alkaline condition, and the surface is chemically sealed with inorganic metal compounds.

30 CFR 75.705-10 - Tying into energized high-voltage surface circuits.

Code of Federal Regulations, 2010 CFR

2010-07-01

....705-10 Tying into energized high-voltage surface circuits. If the work of forming an additional... performing such work must wear and employ all of the protective equipment and clothing required under the... designed for such purpose and must be adequately insulated and be maintained to protect such person from...

40 CFR 761.286 - Sample size and procedure for collecting a sample.

Code of Federal Regulations, 2013 CFR

2013-07-01

... collecting a sample. 761.286 Section 761.286 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... On-Site Disposal of Bulk PCB Remediation Waste and Porous Surfaces in Accordance With § 761.61(a)(6... PCB remediation waste or porous surfaces, collect at least 20 milliliters of waste, or a portion of...

40 CFR 761.286 - Sample size and procedure for collecting a sample.

Code of Federal Regulations, 2011 CFR

2011-07-01

... collecting a sample. 761.286 Section 761.286 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... On-Site Disposal of Bulk PCB Remediation Waste and Porous Surfaces in Accordance With § 761.61(a)(6... PCB remediation waste or porous surfaces, collect at least 20 milliliters of waste, or a portion of...

40 CFR 761.286 - Sample size and procedure for collecting a sample.

Code of Federal Regulations, 2012 CFR

2012-07-01

... collecting a sample. 761.286 Section 761.286 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... On-Site Disposal of Bulk PCB Remediation Waste and Porous Surfaces in Accordance With § 761.61(a)(6... PCB remediation waste or porous surfaces, collect at least 20 milliliters of waste, or a portion of...

40 CFR 761.286 - Sample size and procedure for collecting a sample.

Code of Federal Regulations, 2014 CFR

2014-07-01

... collecting a sample. 761.286 Section 761.286 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... On-Site Disposal of Bulk PCB Remediation Waste and Porous Surfaces in Accordance With § 761.61(a)(6... PCB remediation waste or porous surfaces, collect at least 20 milliliters of waste, or a portion of...

Delivery of Ecosystem Benefits at the Urban-Suburban Interface: A Case Study of Flood Protection in the Woonasquatucket River Watershed

EPA Science Inventory

Urbanization exacerbates flooding by increasing surface runoff and decreasing surface roughness. Restoring wetlands can enhance flood protection while providing a suite of co-benefits such as temperature regulation and access to open space. Spatial modeling of the delivery of flo...

Molecular assemblies as protective barriers and adhesion promotion interlayer

DOEpatents

King, David E.; Czanderna, Alvin W.; Kennedy, Cheryl E.

1996-01-01

A protective diffusion barrier having adhesive qualifies for metalized surfaces is provided by a passivating agent having the formula HS--(CH.sub.2).sub.11 --COOH Which forms a very dense, transparent organized molecular assembly or layer that is impervious to water, alkali, and other impurities and corrosive substances that typically attack metal surfaces.

Surface and interface modification science and technology.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, J.-H.

1999-07-19

Surface modification of solids is of scientific and technological interest due to its significant benefits in a wide variety of applications. Various coatings applications such as corrosion protection and electrical insulators and conductors are required for proper engineering design based on geometrical relationships between interfaces and on thermodynamic/kinetic considerations for the development of surface modifications. This paper will explore three basic examples: the proton conductor BaCeO{sub 3}, high-temperature protective coatings, and epitaxial relationships between interfaces.

30 CFR 77.704-5 - Installation of protective equipment.

Code of Federal Regulations, 2010 CFR

2010-07-01

... high-voltage surface lines is begun, protective equipment shall be used to cover all bare conductors.... Such protective equipment shall be installed from a safe position below the conductors or other...

30 CFR 77.704-5 - Installation of protective equipment.

Code of Federal Regulations, 2011 CFR

2011-07-01

... high-voltage surface lines is begun, protective equipment shall be used to cover all bare conductors.... Such protective equipment shall be installed from a safe position below the conductors or other...

Patterns of protective associations differ for antibodies to P. falciparum-infected erythrocytes and merozoites in immunity against malaria in children.

PubMed

Chan, Jo-Anne; Stanisic, Danielle I; Duffy, Michael F; Robinson, Leanne J; Lin, Enmoore; Kazura, James W; King, Christopher L; Siba, Peter M; Fowkes, Freya Ji; Mueller, Ivo; Beeson, James G

2017-12-01

Acquired antibodies play an important role in immunity to P. falciparum malaria and are typically directed towards surface antigens expressed by merozoites and infected erythrocytes (IEs). The importance of specific IE surface antigens as immune targets remains unclear. We evaluated antibodies and protective associations in two cohorts of children in Papua New Guinea. We used genetically-modified P. falciparum to evaluate the importance of PfEMP1 and a P. falciparum isolate with a virulent phenotype. Our findings suggested that PfEMP1 was the dominant target of antibodies to the IE surface, including functional antibodies that promoted opsonic phagocytosis by monocytes. Antibodies were associated with increasing age and concurrent parasitemia, and were higher among children exposed to a higher force-of-infection as determined using molecular detection. Antibodies to IE surface antigens were consistently associated with reduced risk of malaria in both younger and older children. However, protective associations for antibodies to merozoite surface antigens were only observed in older children. This suggests that antibodies to IE surface antigens, particularly PfEMP1, play an earlier role in acquired immunity to malaria, whereas greater exposure is required for protective antibodies to merozoite antigens. These findings have implications for vaccine design and serosurveillance of malaria transmission and immunity. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Characterization of Textiles Used in Chefs' Uniforms for Protection Against Thermal Hazards Encountered in the Kitchen Environment.

PubMed

Zhang, Han; McQueen, Rachel H; Batcheller, Jane C; Ehnes, Briana L; Paskaluk, Stephen A

2015-10-01

Within the kitchen the potential for burn injuries arising from contact with hot surfaces, flames, hot liquid, and steam hazards is high. The chef's uniform can potentially offer some protection against such burns by providing a protective barrier between the skin and the thermal hazard, although the extent to which can provide some protection is unknown. The purpose of this study was to examine whether fabrics used in chefs' uniforms were able to provide some protection against thermal hazards encountered in the kitchen. Fabrics from chefs' jackets and aprons were selected. Flammability of single- and multiple-layered fabrics was measured. Effect of jacket type, apron and number of layers on hot surface, hot water, and steam exposure was also measured. Findings showed that all of the jacket and apron fabrics rapidly ignited when exposed to a flame. Thermal protection against hot surfaces increased as layers increased due to more insulation. Protection against steam and hot water improved with an impermeable apron in the system. For wet thermal hazards increasing the number of permeable layers can decrease the level of protection due to stored thermal energy. As the hands and arms are most at risk of burn injury increased insulation and water-impermeable barrier in the sleeves would improve thermal protection with minimal compromise to overall thermal comfort. © The Author 2015. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

Modification of surfaces of silver nanoparticles for controlled deposition of silicon, manganese, and titanium dioxides

NASA Astrophysics Data System (ADS)

Apostolova, Tzveta; Obreshkov, B. D.; Ionin, A. A.; Kudryashov, S. I.; Makarov, S. V.; Mel'nik, N. N.; Rudenko, A. A.

2018-01-01

In this work we show that nanometric-thick layers of SiO2, MnO2, and TiO2 may be effectively deposited on various silver nanoparticles (including cubic Ag nanoparticles) covered by a very thin (below 0.4 nm) layer of silver sulphide. The background in Raman measurements generated by sulphide-protected Ag nanoparticles is significantly smaller than that for analogous Ag nanoparticles protected by a monolayer formed from alkanethiols - depositing alkanethiols on a surface of anisotropic silver nanoparticles is the current standard method used for protecting a surface of Ag nanoparticles before depositing a layer of silica. Because of significantly smaller generated Raman background, Ag@SiO2 nanostructures with an Ag2S linkage layer between the silver core and the silica shell are very promising low-background electromagnetic nanoresonators for carrying out Raman analysis of various surfaces - especially using what is known as shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS). Sample SHINERS analyses of various surfaces (including pesticide-contaminated surfaces of tomatoes) using cubic-Ag@SiO2 nanoparticles as electromagnetic nanoresonators are also presented.

Collisional quenching of atoms and molecules on spacecraft thermal protection surfaces

NASA Technical Reports Server (NTRS)

Marinelli, W. J.; Green, B. D.

1988-01-01

Preliminary results of a research program to determine energy partitioning in spacecraft thermal protection materials due to atom recombination at the gas-surface interface are presented. The primary focus of the research is to understand the catalytic processes which determine heat loading on Shuttle, Aeroassisted OTV, and NASP thermal protection surfaces in nonequilibrium flight regimes. Highly sensitive laser diagnostics based on laser-induced fluorescence and resonantly-enhanced multiphoton ionization spectroscopy are used to detect atoms and metastable molecules. At low temperatures, a discharge flow reactor is employed to measure deactivation/recombination coefficients for O-atoms, N-atoms, and O2. Detection methods are presented for measuring O-atoms, O2 and N2, and results for deactivation of O2 and O-atoms on reaction-cured glass and Ni surfaces. Both atom recombination and metastable product formation are examined. Radio-frequency discharges are used to produce highly dissociated beams of atomic species at energies characteristic of the surface temperature. Auger electron spectroscopy is employed as a diagnostic of surface composition in order to accurately define and control measurement conditions.

30 CFR 57.12065 - Short circuit and lightning protection.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Short circuit and lightning protection. 57... MINES Electricity Surface Only § 57.12065 Short circuit and lightning protection. Powerlines, including trolley wires, and telephone circuits shall be protected against short circuits and lightning. ...

30 CFR 57.12065 - Short circuit and lightning protection.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Short circuit and lightning protection. 57... MINES Electricity Surface Only § 57.12065 Short circuit and lightning protection. Powerlines, including trolley wires, and telephone circuits shall be protected against short circuits and lightning. ...

30 CFR 57.12065 - Short circuit and lightning protection.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Short circuit and lightning protection. 57... MINES Electricity Surface Only § 57.12065 Short circuit and lightning protection. Powerlines, including trolley wires, and telephone circuits shall be protected against short circuits and lightning. ...

30 CFR 57.12065 - Short circuit and lightning protection.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Short circuit and lightning protection. 57... MINES Electricity Surface Only § 57.12065 Short circuit and lightning protection. Powerlines, including trolley wires, and telephone circuits shall be protected against short circuits and lightning. ...

30 CFR 57.12065 - Short circuit and lightning protection.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Short circuit and lightning protection. 57... MINES Electricity Surface Only § 57.12065 Short circuit and lightning protection. Powerlines, including trolley wires, and telephone circuits shall be protected against short circuits and lightning. ...

Disorder-driven topological phase transition in B i 2 S e 3 films

DOE PAGES

Brahlek, Matthew; Koirala, Nikesh; Salehi, Maryam; ...

2016-10-03

Topological insulators (TI) are a phase of matter that host unusual metallic states on their surfaces. Unlike the states that exist on the surface of conventional materials, these so-called topological surfaces states (TSS) are protected against disorder-related localization effects by time reversal symmetry through strong spin-orbit coupling. By combining transport measurements, angle-resolved photo-emission spectroscopy and scanning tunneling microscopy, we show that there exists a critical level of disorder beyond which the TI Bi 2Se 3 loses its ability to protect the metallic TSS and transitions to a fully insulating state. The absence of the metallic surface channels dictates that theremore » is a change in material’s topological character, implying that disorder can lead to a topological phase transition even without breaking the time reversal symmetry. This observation challenges the conventional notion of topologically-protected surface states, and will provoke new studies as to the fundamental nature of topological phase of matter in the presence of disorder.« less

Separate RNA-binding surfaces on the multifunctional La protein mediate distinguishable activities in tRNA maturation.

PubMed

Huang, Ying; Bayfield, Mark A; Intine, Robert V; Maraia, Richard J

2006-07-01

By sequence-specific binding to 3' UUU-OH, the La protein shields precursor (pre)-RNAs from 3' end digestion and is required to protect defective pre-transfer RNAs from decay. Although La is comprised of a La motif and an RNA-recognition motif (RRM), a recent structure indicates that the RRM beta-sheet surface is not involved in UUU-OH recognition, raising questions as to its function. Progressively defective suppressor tRNAs in Schizosaccharomyces pombe reveal differential sensitivities to La and Rrp6p, a 3' exonuclease component of pre-tRNA decay. 3' end protection is compromised by mutations to the La motif but not the RRM surface. The most defective pre-tRNAs require a second activity of La, in addition to 3' protection, that requires an intact RRM surface. The two activities of La in tRNA maturation map to its two conserved RNA-binding surfaces and suggest a modular model that has implications for its other ligands.

Progress in Protective Coatings for Aircraft Gas Turbines: A Review of NASA Sponsored Research

NASA Technical Reports Server (NTRS)

Merutka, J. P.

1981-01-01

Problems associated with protective coatings for advanced aircraft gas turbines are reviewed. Metallic coatings for preventing titanium fires in compressors are identified. Coatings for turbine section are also considered, Ductile aluminide coatings for protecting internal turbine-blade cooling passage surface are also identified. Composite modified external overlay MCrAlY coatings deposited by low-pressure plasma spraying are found to be better in surface protection capability than vapor deposited MCrAlY coatings. Thermal barrier coating (TBC), studies are presented. The design of a turbine airfoil is integrated with a TBC, and computer-aided manufacturing technology is applied.

Concepts of skin protection: considerations for the evaluation and terminology of the performance of skin protective equipment.

PubMed

Brouwer, Derk H; Aitken, Robert J; Oppl, Reinhard; Cherrie, John W

2005-09-01

This article proposes a common language for better understanding processes involved in dermal exposure and skin protection. A conceptual model has been developed that systematically describes the transport of agent mass from sources, eventually resulting in "loading" of the skin surface or the skin contaminant layer. In view of a harmonized glossary of exposure terminology this is considered the exposure surface. Loading is defined as agent mass present in this layer divided by the exposure surface area. Skin protective equipment (SPE) is meant to reduce uptake, that is, an agent crosses the absorption barrier of the skin, by intervening in the processes of loading the exposure surface; however, the design of the equipment may fail to cover skin surface entirely. In addition, part of the mass intercepted by the SPE may reach the skin surface either by permeation, penetration, or by transfer when touching the contaminated exterior of the SPE. Evaluation of SPE performance has earlier focused on chemical resistance performance testing for permeation, penetration, or degradation of SPE-materials. In use-scenario practice, however, all processes will occur concurrently. Thus, SPE field performance evaluation including user-SPE interaction complementary to material testing is warranted. Results of laboratory testing for SPE-materials are reported as substance-specific breakthrough times and permeation rates. SPE field performance should be evaluated for reduction of either uptake or parameters that reflect the outcome of dermal exposure. Ideally, this should be based on the results of intervention-type workplace studies, for (e.g., assessment of exposure loading). The level of reduction can be expressed as a protection factor (ratio without/with SPE) for different parameters of dermal exposure or uptake. It is concluded that for evaluation of SPE-type performance, generic protection factors can be derived for substance-independent processes (e.g., reduction of exposure loading) but not for substance-specific reduction of uptake.

Output-increasing, protective cover for a solar cell

DOEpatents

Hammerbacher, Milfred D.

1995-11-21

A flexible cover (14) for a flexible solar cell (12) protects the cell from the ambient and increases the cell's efficiency. The cell(12)includes silicon spheres (16) held in a flexible aluminum sheet matrix (20,22). The cover (14) is a flexible, protective layer (60) of light-transparent material having a relatively flat upper, free surface (64) and an irregular opposed surface (66). The irregular surface (66) includes first portions (68) which conform to the polar regions (31R) of the spheres (16) and second convex (72) or concave (90) portions (72 or 90) which define spaces (78) in conjunction with the reflective surface (20T) of one aluminum sheet (20). Without the cover (14) light (50) falling on the surface (20T) between the spheres (16) is wasted, that is, it does not fall on a sphere (16). The surfaces of the second portions are non-parallel to the direction of the otherwise wasted light (50), which fact, together with a selected relationship between the refractive indices of the cover and the spaces, result in sufficient diffraction of the otherwise wasted light (50) so that about 25% of it is reflected from the surface (20T) onto a sphere (16).

SURFACE HARDENING OF TITANIUM BY TREATMENT IN MOLTEN BORAX

DOE Office of Scientific and Technical Information (OSTI.GOV)

Minkevich, A.N.; Shul'ga, Yu.N.

1957-01-01

The surface hardening of titanium and titanium alloys by treatment in molten borax was investigated. Commercial titanium, a titanium-tungsten alloy, and an aluminum-chromium-titanium alloy were used for the experiments. To prevent oxidation of the titanium and to protect the surface, electro-chemical protection was applied, the current density being 0.1 amp/cm/sup 2/ and the the specimens were coated with a thin layer of borax. The results showed that treatment in molten borax is an effective method of increasing surface hardness. However, the strength, mmalleabiltiy, and toughness of the hardness increase is discussed. (J.S.R.)

Method of protecting surfaces from abrasion and abrasion resistant articles of manufacture

DOEpatents

Hirschfeld, T.B.

1988-06-09

Surfaces of fabricated structures are protected from damage by impacting particulates by a coating of hard material formed as a mass of thin flexible filaments having root ends secured to the surface and free portions which can flex and overlap to form a resilient cushioning mat which resembles hair or fur. The filamentary coating covers the underlying surface with hard abrasion resistance material while also being compliant and capable of local accommodation to particle impacts. The coating can also function as thermal and/or acoustical insulation and has a friction reducing effect. 11 figs.

Enhanced protective properties of epoxy/polyaniline-camphorsulfonate nanocomposite coating on an ultrafine-grained metallic surface

NASA Astrophysics Data System (ADS)

Pour-Ali, Sadegh; Kiani-Rashid, Alireza; Babakhani, Abolfazl; Davoodi, Ali

2016-07-01

An ultrafine-grained surface layer on mild steel substrate with average grain size of 77 nm was produced through wire brushing process. Surface grain size was determined through transmission electron microscopy and X-ray diffraction methods. This substrate was coated with epoxy and an in situ synthesized epoxy/polyaniline-camphorsulfonate (epoxy/PANI-CSA) nanocomposite. The corrosion behavior was studied by open circuit potential, potentiodynamic polarization and impedance measurements. Results of electrochemical tests evidenced the enhanced protective properties of epoxy/PANI-CSA coating on the substrate with ultrafine-grained surface.

30 CFR 57.15014 - Eye protection when operating grinding wheels.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Eye protection when operating grinding wheels. 57.15014 Section 57.15014 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF... NONMETAL MINES Personal Protection Surface and Underground § 57.15014 Eye protection when operating...

30 CFR 57.15014 - Eye protection when operating grinding wheels.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Eye protection when operating grinding wheels. 57.15014 Section 57.15014 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF... NONMETAL MINES Personal Protection Surface and Underground § 57.15014 Eye protection when operating...

Epoxy blanket protects milled part during explosive forming

NASA Technical Reports Server (NTRS)

1966-01-01

Epoxy blanket protects chemically milled or machined sections of large, complex structural parts during explosive forming. The blanket uniformly covers all exposed surfaces and fills any voids to support and protect the entire part.

On-the-Job Foot Health

MedlinePlus

... and direct flame PROTECTION: overshoes or boots of fire-resistant materials with wooden soles HAZARD: high voltage PROTECTION: shoes with rubber or cork heels and soles, and no exposed metal parts HAZARD: hot surfaces PROTECTION: safety shoes with ...

29 CFR 1915.51 - Ventilation and protection in welding, cutting and heating.

Code of Federal Regulations, 2010 CFR

2010-07-01

... from the exposed arc, and surfaces prepared with chlorinated solvents shall be thoroughly dry before... heating shall be protected by suitable eye protective equipment in accordance with the requirements of...

Waste-indicator and pharmaceutical compounds in landfill-leachate-affected ground water near Elkhart, Indiana, 2000-2002

USGS Publications Warehouse

Buszka, P.M.; Yeskis, D.J.; Kolpin, D.W.; Furlong, E.T.; Zaugg, S.D.; Meyer, M.T.

2009-01-01

Four wells downgradient from a landfill near Elkhart, Indiana were sampled during 2000-2002 to evaluate the presence of waste-indicator and pharmaceutical compounds in landfill-leachate-affected ground water. Compounds detected in leachate-affected ground water included detergent metabolites (p-nonylphenol, nonylphenol monoethoxylate, nonylphenol diethoxylate, and octylphenol monoethoxylate), plasticizers (ethanol-2-butoxy-phosphate and diethylphthalate), a plastic monomer (bisphenol A), disinfectants (1,4-dichlorobenzene and triclosan), an antioxidant (5-methyl-1H-benzotriazole), three fire-retardant compounds (tributylphosphate and tri(2-chloroethyl)phosphate, and tri(dichlorisopropyl)phosphate), and several pharmaceuticals and metabolites (acetaminophen, caffeine, cotinine, 1,7-dimethylxanthine, fluoxetine, and ibuprofen). Acetaminophen, caffeine, and cotinine detections confirm prior indications of pharmaceutical and nicotinate disposal in the landfill. ?? 2009 Springer Science + Business Media, LLC.

Browns Ferry Nuclear Plant low-level radwaste storage facility ground-water pathway analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boggs, J.M.

1982-10-01

The proposed low-level radwaste storage facility (LLRWSF) at Browns Ferry Nuclear Plant is underlain by soils having low hydraulic conductivity and high sorptive capacity which greatly reduce the risks associated with a potential contaminant excursion. A conservative ground-water pathway accident analysis using flow and solute transport modeling techniques indicates that without interdiction the concentrations of the five radionuclides of concern (Sr-90, Cs-137, Cs-134, Co-60, and Mn-54) would be well below 10 CFR Part 20 criteria at downgradient receptors. These receptors include a possible future private water well located near the eastern site boundary and Wheeler Reservoir. Routine ground-water monitoring ismore » not recommended at the LLRWSF except in the unlikely event of an accident.« less

Color and opacity of composites protected with surface sealants and submitted to artificial accelerated aging.

PubMed

Aguilar, Fabiano Gamero; Roberti Garcia, Lucas da Fonseca; Cruvinel, Diogo Rodrigues; Sousa, Ana Beatriz Silva; de Carvalho Panzeri Pires-de-Souza, Fernanda

2012-01-01

To evaluate the color similarity, stability and opacity of composites (TPH, Charisma, and Concept, shade A2) protected with surface sealants (Fortify Plus and Biscover) and cyanoacrylate (Super Bonder). Forty specimens of each composite were made and separated into 4 groups (n=10) according to the surface protection: GI - without sealant; GII - cyanoacrylate; GIII - Fortify Plus; GIV - Biscover. Color and opacity readings were taken before and after Artificial Acelerated Aging (AAA) and the values obtained for color stability were submitted to statistical analysis by 2-way ANOVA and Bonferroni's test (P<.05). The values acquired for color similarity were submitted to 1-way ANOVA and Tukey's test (P<.05). The specimen sufaces were compared before and after AAA using Scanning Electronic Microscopy (SEM). Studied composites did not present the same values for the coordinates L*, a* and b * before AAA, indicating that there was no color similarity among them. All composites presented color alteration after AAA with clinically unacceptable values. Protected groups presented lower opacity variation after AAA, in comparison with the control goup. SEM evaluation demonstrated that AAA increased the surface irregularities in all of the studied groups. Surface sealants were not effective in maintaining composite color, but were able to maintain opacity.

A New Green Ionic Liquid-Based Corrosion Inhibitor for Steel in Acidic Environments.

PubMed

Atta, Ayman M; El-Mahdy, Gamal A; Al-Lohedan, Hamad A; Ezzat, Abdel Rahman O

2015-06-17

This work examines the use of new hydrophobic ionic liquid derivatives, namely octadecylammonium tosylate (ODA-TS) and oleylammonium tosylate (OA-TS) for corrosion protection of steel in 1 M hydrochloric acid solution. Their chemical structures were determined from NMR analyses. The surface activity characteristics of the prepared ODA-TS and OA-TS were evaluated from conductance, surface tension and contact angle measurements. The data indicate the presence of a double bond in the chemical structure of OA-TS modified its surface activity parameters. Potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) measurements, scanning electron microscope (SEM), Energy dispersive X-rays (EDX) analysis and contact angle measurements were utilized to investigate the corrosion protection performance of ODA-TS and OA-TS on steel in acidic solution. The OA-TS and ODA-TS compounds showed good protection performance in acidic chloride solution due to formation of an inhibitive film on the steel surface.

Role of SiC substrate surface on local tarnishing of deposited silver mirror stacks

NASA Astrophysics Data System (ADS)

Limam, Emna; Maurice, Vincent; Seyeux, Antoine; Zanna, Sandrine; Klein, Lorena H.; Chauveau, Grégory; Grèzes-Besset, Catherine; Savin De Larclause, Isabelle; Marcus, Philippe

2018-04-01

The role of the SiC substrate surface on the resistance to the local initiation of tarnishing of thin-layered silver stacks for demanding space mirror applications was studied by combined surface and interface analysis on model stack samples deposited by cathodic magnetron sputtering and submitted to accelerated aging in gaseous H2S. It is shown that suppressing the surface pores resulting from the bulk SiC material production process by surface pretreatment eliminates the high aspect ratio surface sites that are imperfectly protected by the SiO2 overcoat after the deposition of silver. The formation of channels connecting the silver layer to its environment through the failing protection layer at the surface pores and locally enabling H2S entry and Ag2S growth as columns until emergence at the stack surface is suppressed, which markedly delays tarnishing initiation and thereby preserves the optical performance. The results revealed that residual tarnishing initiation proceeds by a mechanism essentially identical in nature but involving different pathways short circuiting the protection layer and enabling H2S ingress until the silver layer. These permeation pathways are suggested to be of microstructural origin and could correspond to the incompletely coalesced intergranular boundaries of the SiO2 layer.

UV hazard on a summer's day under Mediterranean conditions, and the protective role of a beach umbrella

NASA Astrophysics Data System (ADS)

Grifoni, D.; Carreras, G.; Sabatini, F.; Zipoli, G.

2005-11-01

Mediterranean beaches are very crowded during summer and, because of the high values of solar UV radiation, the potential risk for human health is relevant. In this study, all-day measurements of biologically effective global and diffuse UV radiation for skin (UVBEeryt) and eye (UVBEpker, UVBEpconj, UVBEcat) disorders were carried out on differently tilted surfaces on a summer’s day on a Mediterranean beach. The role played by beach umbrellas in protection from excessive sun exposure was also investigated. Erythema, photokeratitis and cataract seem to require almost the same exposure time to reach the risk threshold dose. Under full sunlight, the highest global and diffuse UV values are reached on surfaces normally oriented towards sunlight and on horizontal surfaces, respectively. Over vertical surfaces, at this northern hemisphere site, global and diffuse UV radiation reaches maxima values in the south-facing direction around noon, while maxima values are reached early in the morning and late in the afternoon over surfaces facing east and west, respectively. The quality of the beach umbrella’s protection (efficiency in blocking solar UV radiation) varies with surface orientation; the highest efficiency for our specific site and geometrical conditions occurs over horizontal surfaces, with efficiency being least over vertical surfaces when incident radiation values are still relevant.

Towards understanding the mechanisms and the kinetics of nanoparticle penetration through protective gloves

NASA Astrophysics Data System (ADS)

Vinches, L.; Peyrot, C.; Lemarchand, L.; Boutrigue, N.; Zemzem, M.; Wilkinson, K. J.; Hallé, S.; Tufenkji, N.

2015-05-01

Parallel to the increased use of engineered nanoparticles (ENP) in the formulation of commercial products or in medicine, numerous health & safety agencies have recommended the application of the precautionary principle to handle ENP; namely, the recommendation to use protective gloves against chemicals. However, recent studies reveal the penetration of titanium dioxide nanoparticles through nitrile rubber protective gloves in conditions simulating occupational use. This project is designed to understand the links between the penetration of gold nanoparticles (nAu) through nitrile rubber protective gloves and the mechanical and physical behaviour of the elastomer material subjected to conditions simulating occupational use (i.e., mechanical deformations (MD) and sweat). Preliminary analyses show that nAu suspensions penetrate selected glove materials after exposure to prolonged (3 hours) dynamic deformations. Significant morphological changes are observed on the outer surface of the glove sample; namely, the number and the surface of the micropores on the surface increase. Moreover, nitrile rubber protective gloves are also shown to be sensitive to the action of nAu suspension and to the action of the saline solution used to simulate sweat (swelling).

Effects of surface applications of biosolids on soil, crops, ground water, and streambed sediment near Deer Trail, Colorado, 1999-2003

USGS Publications Warehouse

Yager, Tracy J.B.; Smith, David B.; Crock, James G.

2004-01-01

The U.S. Geological Survey, in cooperation with Metro Wastewater Reclamation District and North Kiowa Bijou Groundwater Management District, studied natural geochemical effects and the effects of biosolids applications to the Metro Wastewater Reclamation District properties near Deer Trail, Colorado, during 1999 through 2003 because of public concern about potential contamination of soil, crops, ground water, and surface water from biosolids applications. Parameters analyzed for each monitoring component included arsenic, cadmium, copper, lead, mercury, molybdenum, nickel, selenium, and zinc (the nine trace elements regulated by Colorado for biosolids), gross alpha and gross beta radioactivity, and plutonium, as well as other parameters. Concentrations of the nine regulated trace elements in biosolids were relatively uniform and did not exceed applicable regulatory standards. All plutonium concentrations in biosolids were below the minimum detectable level and were near zero. The most soluble elements in biosolids were arsenic, molybdenum, nickel, phosphorus, and selenium. Elevated concentrations of bismuth, mercury, phosphorus, and silver would be the most likely inorganic biosolids signature to indicate that soil or streambed sediment has been affected by biosolids. Molybdenum and tungsten, and to a lesser degree antimony, cadmium, cobalt, copper, mercury, nickel, phosphorus, and selenium, would be the most likely inorganic 'biosolids signature' to indicate ground water or surface water has been affected by biosolids. Soil data indicate that biosolids have had no measurable effect on the concentration of the constituents monitored. Arsenic concentrations in soil of both Arapahoe and Elbert County monitoring sites (like soil from all parts of Colorado) exceed the Colorado soil remediation objectives and soil cleanup standards, which were determined by back-calculating a soil concentration equivalent to a one-in-a-million cumulative cancer risk. Lead concentrations in soil slightly exceed the U.S. Environmental Protection Agency toxicity-derived ecological soil-screening levels for avian wildlife. Plutonium concentration in the soil was near zero. Wheat-grain data were insufficient to determine any measurable effects from biosolids. Comparison with similar data from other parts of North America where biosolids were not applied indicates similar concentrations. However, the Deer Trail study area had higher nickel concentrations in wheat from both the biosolids-applied fields and the control fields. Plutonium content of the wheat was near zero. Ground-water levels generally declined at most wells during 1999 through 2003. Ground-water quality did not correlate with ground-water levels. Vertical ground-water gradients during 1999 through 2003 indicate that bedrock ground-water resources downgradient from the biosolids-applied areas are not likely to be contaminated by biosolids applications unless the gradients change as a result of pumping. Ground-water quality throughout the study area varied over time at each site and from site to site at the same time, but plutonium concentrations in the ground water always were near zero. Inorganic concentrations at well D6 were relatively high compared to other ground-water sites studied. Ground-water pH and concentrations of fluoride, nitrite, aluminum, arsenic, barium, chromium, cobalt, copper, lead, mercury, nickel, silver, zinc, and plutonium in the ground water of the study area met Colorado standards. Concentrations of chloride, sulfate, nitrate, boron, iron, manganese, and selenium exceeded Colorado ground-water standards at one or more wells. Nitrate concentrations at well D6 significantly (alpha = 0.05) exceeded the Colorado regulatory standard. Concentrations of arsenic, cadmium, chromium, lead, mercury, nickel, and zinc in ground water had no significant (alpha = 0.05) upward trends. During 1999-2003, concentrations of nitrate, copper, molybdenum, and selenium

Protective coatings of metal surfaces by cold plasma treatment

NASA Technical Reports Server (NTRS)

Manory, R.; Grill, A.

1985-01-01

The cold plasma techniques for deposition of various types of protective coatings are reviewed. The main advantage of these techniques for deposition of ceramic films is the lower process temperature, which enables heat treating of the metal prior to deposition. In the field of surface hardening of steel, significant reduction of treatment time and energy consumption were obtained. A simple model for the plasma - surface reactions in a cold plasma system is presented, and the plasma deposition techniques are discussed in view of this model.