bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of Hydraulic Conductivity Values Obtained from Aquifer Pumping Tests and Conservative Tracer Tests
Authors: Niemann William L. , Rovey Charles W.
Published: February 2007

Afield site was established in an area of glacial outwash near Des Moines, Iowa. Hydraulic conductivity (K) of the outwash was measured in various ways including six pumping tests and two natural‐gradient Cl‐ tracer tests. The velocity of the conservative tracer was converted to K using measured gradients and effective porosity determined from two radial‐convergent Cl‐ tracer tests.

K values measured from the conservative tracer tests are approximately one‐tenth to one‐twentieth the average pumping‐test value. Thus the K relevant to solute transport does not reflect the K measured by pumping tests. This discrepancy may be caused by the different scale and dimensionality of the two test types. Dispersion may prevent solutes from flowing exclusively within smaller high‐conductivity paths which strongly affect the K measured by pumping tests.
Decision Analysis for Pump‐and‐Treat Design
Authors: Russell Kevin T. , Rabideau Alan. J.
Published: February 2007

The use of decision analysis (DA) has been proposed as a technique for selecting from among alternative designs for subsurface remediation. To assess the ability of DA to generate consistent decisions for the widely practiced pump‐and‐treat (PAT) strategy, 27 candidate PAT designs were compared for a case study site. The sensitivity of the alternative selection to various modeling assumptions was examined, including the complexity of the site‐specific numerical models, the assumed degree of aquifer heterogeneity, the manner of defining failure, and the assumed cost of failure. The initial net‐present‐worth analysis resulted in the selection of one of two designs that included injection wells for effluent disposal and hydraulic control. However, when the injection wells were excluded from consideration, the selection from a diverse set of alternative PAT designs was highly sensitive to the particular modeling assumptions. In general, the practical usefulness of the DA approach is dependent on the ability to characterize the nature and probability of system failure.
Field Tests of a DNAPL Characterization System Using Cone Penetrometer‐Based Raman Spectroscopy
Authors: Rossabi J. , Riha B.D. , III J.W. Hass , Eddy‐Dilek C.A. , Lustin A.G. , Carrabba M. , Hyde W.K. , Bello J.
Published: February 2007

Cone penctrometer test (CPT) based Raman spectroscopy was used to identify separate phase tetrachloroethylene (PCE) and trichlorocthylene (TCE) contamination in the subsurface at two locations during field tests conducted at the U.S. Department of Energy's (DOE) Savannah River site. Clear characteristic Raman spectral peaks for PCE and TCE were observed at two sites and several depths during CPT deployment. Because of the uniqueness of a Raman spectrum for a given compound, these data are compelling evidence of the presence of the two compounds. The Raman spectral results correlated with high PCE and TCE concentrations in soil samples collected from the same subsurface zones, confirming that the method is a viable dense nonaqueous phase liquid (DNAPL) characterization technique. The Raman spectroscopic identification of PCE and TCE in these tests represents the first time that DNAPLs have been unequivocally located in the subsurface by an in situ technique.

The detection limit of the Raman spectroscopy is related to the probability of contaminant droplets appearing on the optical window in the path of the probe light. Based on data from this fieldwork the Raman technique may require a threshold quantity of DNAPL to provide an adequate optical cross section for spectroscopic response. The low aqueous solubility of PCE and TCE and relatively weak optical intensity of the Raman signal precludes the detection of aqueous phase contaminants by this method, making it selective for DNAPL contaminants only.
Occurrence of MTBE in Heating Oil and Diesel Fuel in Connecticut
Authors: Robbins Gary A. , Henebry Brent J. , Cummins Timothy M. , Goad Christopher R. , Gilbert Edward J.
Published: February 2007

The objective of this study was to confirm if MTBE, which is not intentionally added to fuels other than gasoline, is a contaminant in heating oil and diesel fuel. The study entailed conducting a statewide sampling program of heating oil and diesel fuel in Connecticut. An analytical method was developed to conduct analyses of heating oil and diesel fuel for MTBE in the milligram per liter (mg/L) range. The method involved equilibrating product with water to extract MTBE followed by static head‐space analysis on aliquots of the water. Analyses were conducted using a gas chromatograph with a MTBE specific column. The statewide sampling program confirmed the widespread occurrence of MTBE in heating oil and diesel fuel. MTBE was detected in all samples collected during our sampling program at concentrations ranging from 9.7 to 906 mg/L in heating oil (26 samples), and from 74 to 120 mg/L in diesel fuel (five samples). Based on these ranges. MTBE concentrations in ground water in the vicinity of heating oil and diesel fuel releases could exceed thousands of micrograms per liter. Our analysis would suggest that the levels of heating oil and diesel fuel contamination observed could result from the commingling of only a few parts gasoline with thousands of parts of these fuels. The extent to which MTBE occurs in heating oil and diesel fuel nationwide is not known, but our data suggests that it may be widespread.
Laboratory and Numerical Investigations of Air Sparging Using MTBE as a Tracer
Authors: Mortensen Annette Pia , Jensen Karsten Høgh , Sonnenborg Torben Obel , Arvin Erik
Published: February 2007

Air sparging experiments were conducted in a laboratory column to investigate air flow and mass transfer behavior in different types of sand at different air injection rates. Methyl tertiary butyl ether (MTBE) was applied as a tracer, and by measuring the volatilization and the mean air content during the experiments, the air flow pattern and its influence on mass transfer were assessed. The experimental results showed large differences among the sand types. In fine sand, the mean air content was high and the volatilization of MTBE was rapid with total recovery after a few hours. In coarse sand, the mean air content was low and the volatilization of MTBE was limited. The results indicate two different air flow distributions. In fine‐grained materials, a uniform air distribution can be expected compared to coarse‐grained materials where isolated air channels will limit the mass transfer. Afterwards, the experiments were simulated using the numerical multiphase flow code T2VOC, and the results compared to those obtained in the laboratory. The experiments with fine sand were simulated well, while for coarser sand types the volatilization was highly overestimated. The differences between model and laboratory results were mainly attributed to the nonuniformity of the air saturation and the neglection of kinetics in the mass transfer formulation.
Efficient Quantification of Total Petroleum Hydrocarbons and Applications at Two Contaminated Sites
Authors: Xie Guibo , Barcelona Michael J.
Published: February 2007

Characterization and remediation of petroleum contamination are complicated issues due to variable product compositions and site conditions. Generic group analytical methods such as total petroleum hydrocarbon (TPH) methods have played important field screening and regulatory functions for site characterization and cleanup. This study evaluated the application of three TPH methods (a GC/MS method, a spectrometric method EPA 418.1, and a rapid field method PetroFLAG). The results showed that quantification of TPH could be attained efficiently by a combination of rapid field methods (i.e., PetroFLAG) and more sophisticated fraction‐specific and target‐compound methods. TPH distributions suggested different source release information for two sites with different contaminant mixtures and climate conditions. TPH was also found to correlate with reductive redox capacity (RDC), an important parameter for the design of oxidative remediation schemes. The results indicated that good site specific correlations could be established to better estimate costs of the injection of chemical oxidants if necessary. RDC values varied broadly for both background (83 ˜ 569 meq/kg) and contaminated source (523 ˜ 6044 meq/kg) samples collected from actual sites.
Monitored Natural Attenuation of Contaminants in the Subsurface: Processes
Authors: Azadpour‐Keeley Ann , Keeley Jack W. , Russell Hugh H. , Sewell Guy W.
Published: February 2007

Among the alternatives considered for the remediation of soil and ground water at hazardous wastes sites are the use of natural processes to reduce or remove the contaminants of concern, Under favorable conditions, the use of natural attenuation can result in significant cost savings and compensate for uncertainties encountered in complex subsurface settings. In order to demonstrate that natural processes are effective in reaching established goals it is necessary to determine that transformation processes are taking place at a rate which is protective of human health and the environment, and that these processes will continue for an acceptable period of time.

While chemical transformation, dispersion, dilution, sorption, and volatilization are discussed, aerobic and anaerobic degradation comprise the major processes for the reduction of contaminant mass in the subsurface. In discussing the mechanisms of natural attenuation, chlorinated aliphatics and petroleum hydrocarbons are used as examples because of their significant impact on subsurface contamination and the effect of their physiochemical properties on attenuation processes.
Effective Air Delivery from a Horizontal Sparging Well
Authors: Lundegard Paul D. , Chaffee Brent , LaBrecque Doug
Published: February 2007

Horizontal air sparging (HASP) wells offer several potential advantages compared to linear arrays of vertical air sparging wells. For some of these advantages to be realized, however, HASP wells must be able to deliver air uniformly along the length of the well. HASP wells can fail to deliver air uniformly for either engineering or geological reasons.

A 58 m (190‐foot) long HASP well, with a 15 m (50‐foot) long screen interval, was designed, installed, and tested in eolian dune sand. The relative uniformity of the geologic medium allowed specific evaluation of the impact of the well design on air delivery. A variety of monitoring approaches were used during a six‐day pilot test. Pressure drop within the sparge well was found to be negligible through the screen interval of the well. Soil gas pressure and ground water mounding responses were very similar at both ends of the well screen, suggesting relatively uniform air delivery throughout. Electrical resistance tomography results confirmed that airflow in the formation was similar at both ends of the screen interval and that the principal region of airflow was within 1.5 m (5 feet) of the axis of the well. Increased dissolved oxygen was primarily limited to a region within 2.3 m (7.5 feet) of the well and occurred throughout the length of the screen interval. These monitoring results show that HASP wells, properly constructed and installed, can supply air in a generally uniform manner along their length.
Laboratory Evaluation of the Use of Surfactants for Ground Water Remediation and the Potential for Recycling Them
Authors: Lee Dal‐Heui , Cody Robert D. , Hoyle Elythe L.
Published: February 2007

The primary goal of this study was to develop a suitable experimental and laboratory methodology for investigating the efficiency of surfactants in removing hydrophobic contaminants from sand and the efficient recovery of used surfactant solutions for reuse. One of the goals of this study was to test the use of a hydrophile‐lipophile balance (HLB) number as a suitable selection criterion. We used toluene as a model contaminant, Ottawa sand as a model porous medium, and six nontoxic, water‐soluble anionic or nonionic surfactants with HLB numbers ranging from 12 to greater than 25.

Four of the six surfactants were judged to be less suitable on the basis of their properties (less suitable HLB and surface tension), and on batch experiments using separatory funnel, shaker table, and centrifugation methods. The two most suitable surfactants were trideceth‐19‐carboxylic acid (TDCA), an anionic surfactant, and polyoxypropylene‐polyoxyethylene block copolymer (POP‐POE), a nonionic surfactant. These two surfactants were then used for sand column leach experiments, and two of the less suitable surfactants were also investigated to determine if HLB number and batch experiments satisfactorily predicted leaching effectiveness.

In sand column experiments, an aqueous surfactant solution containing a mixture of 1% anionic and 1% nonionic surfactant in a 1.6% NaOH solution was the most effective in removing the toluene. Removal efficiency of alkylaryl ethoxylate carboxylic acid (AECA), which has an HLB number of 19, was only slightly less than for the chemically similar TDCA, but that of dioctyl sulfosuccinate (DOSS) with an HLB greater than 25 was much less effective. These results indicate that HLB number alone is not a perfect indicator of surfactant effectiveness for leaching hydrophobic contaminants because the chemical structure of the surfactant is also important. In the counter‐current solvent extraction experiments designed to allow reuse of surfactants, the anionic surfactant solution (2% TDCA) was the most effectively recycled.
Use of LIF for Real‐Time In‐Situ Mixed NAPL Source Zone Detection
Authors: Kram Mark L. , Lieberman Stephen H. , Fee Jerry , Keller Arturo A.
Published: February 2007

The site characterization and analysis cone penetrometer system (SCAPS), equipped with realtime fluorophore detection capabilities, was used to delineate subsurface contaminant releases in an area where plating shop waste was temporarily stored. Records indicated that various nonaqueous phase liquids (NAPLs) were released at the site. The investigators advanced the SCAPS laser‐induced fluorescence (LIF) sensor to depths beneath the water table of the principal water‐bearing zone. The water table was located approximately 6 feet (1.8 m) below ground surface (bgs) across the site. Fluorescence, attributed to fuel compounds commingled with chlorinated solvents, was observed at depths ranging from 4.0 to 11.5 feet (1.2 to 3.5 m) bgs. Fluorescence, attributed to naturally occurring organic materials (by process of elimination and spectral characteristics) commingled with chlorinated solvent constituents, was observed at depths ranging from approximately 13 to 40 feet (4.0 to 12.2 m) bgs. Fluorescence responses from compounds confirmed to be commingled with chlorinated solvents indicates that the SCAPS fluorophore detection system is capable of indirectly delineating vadose zone and subaqueous chlorinated solvents and other dense nonaqueous phase liquids (DNAPLs) at contaminant release sites. This confirmation effort represents the first documented account of the successful application of LIF to identify a mixed DNAPL/LNAPL source zone.
Field Measurement of Dissolved Oxygen: A Comparison of Methods
Authors: Wilkin Richard T. , McNeil Mary S. , Adair. Cherri. J. , Wilson John T.
Published: February 2007

The ability to confidently measure the concentration of dissolved oxygen (D.O.) in ground water is a key aspect of remedy selection and assessment. Presented here is a comparison of the commonly practiced methods for determining D.O. concentrations in ground water, including colorimetric, membrane‐covered electrode, and modified Winkler techniques. The Winkler titration (azide and permanganate modifications) is the most accurate and precise technique for determining D.O. and is appropriate for applications with stringent data quality objectives. In addition, excellent correlation over a wide range of D.O. concentrations was found between Winkler titrations and colorimetric tests using the rhodazine D (below 1 part per million [ppm]) and indigo carmine reagents (above 1 ppm). Electrode measurements represent the simplest method for determining D.O. concentrations on a continuous basis and electrode determinations positively correlate with Winkler results above 1 ppm. Below 1 ppm, electrodes provide only a qualitative measure of low D.O. level, apparently due to slow electrode response.
DNAPL Removal from a Heterogeneous Alluvial Aquifer by Surfactant‐ Enhanced Aquifer Remediation
Authors: Londergan John T. , Meinardus Hans W. , Manner Paul E. , Jackson Richard E. , Brown Chris L. , Dwarakanath Varadarajan , Pope Gary A. , Ginn Jon S. , Taffinder Sam
Published: February 2007

A demonstration of surfactant‐enhanced aquifer remediation (SEAR) was conducted at Hill Air Force Base (AFB), Utah. Two surfactant floods were undertaken in a test section of a heterogeneous alluvial aquifer with a hydraulic conductivity range of 2.8 to 8.6 ft/day (10‐5 to 10‐4 m/sec) and a pore volume of approximately 15,000 gallons (57 m3). The wellfield installed for the demonstration consisted of lines of three injection and three extraction wells, a central monitoring well, and a single hydraulic control well. No physical barriers to flow, such as sheet‐pile walls, were employed; surfactant flooding was controlled entirely by hydraulic manipulation of the flow field. The inter‐well distance between injectors and extractors was 20 feet (6 m); the distance between individual injectors and extractors in line was 10 feet (3 m). The water table was 25 feet (7.6 m) below ground surface with a saturated zone approximately 19‐feet thick (5.8 m). Residual dense nonaqueous phase liquids (DNAPL) remained in a zone of alluvium 42 to 46 feet (13 to 14 m) below ground surface following extraction of free‐phase DNAPL. The injectors and extractors were screened in this DNAPL zone. Three partitioning interwell tracer tests (PITTs) and two surfactant floods were conducted over four months during 1996. The surfactant floods removed 341 out of 346 gallons of residual DNAPL (1290 of 1310 L), according to the PITTs. This represents a total recovery of about 98.5% of the DNAPL volume present in the zone of residual DNAPL as determined by comparing the initial and final PITTs. There was no reduction in hydraulic conductivity due to colloid mobilization during the surfactant floods; in fact, the hydraulic gradient across the test zone decreased as the floods progressed. Concentrations of dissolved total chlorinated hydrocarbons in the test section decreased from 1000 mg/L before the floods to less than 10 mg/L following the floods. This demonstration is evidence of the technical practicability of DNAPL removal from alluvium.
Evaluation of BTEX Remediation by Natural Attenuation at a Coastal Facility
Authors: Suarez Monica P. , Rifai Hanadi S.
Published: February 2007

Natural attenuation has emerged as a potential alternative for remediating sites contaminated with fuel hydrocarbons. This paper examines the viability of using attenuation through natural processes to remediate ground water at an industrial facility. The research combined field assessments with data analysis and modeling to evaluate plume stability and predict remediation times. Field data on natural attenuation indicate that BTEX contamination at the site is being attenuated at rates that vary within the range of 0.0001 to 0.0073/day. Stability analyses confirm that the BTEX plume has reached steady state. An analysis on mass flux showed that between 1979 and 1996, 95,000 pounds of BTEX were lost via biodegradation, while 8000 pounds were lost through other mechanisms. A first‐order biodegradation rate of 0.0002/day for BTEX was obtained from the change in the total mass of dissolved BTEX with time. Cleanup times in excess of 200 years for the site were estimated using analytical modeling of natural attenuation, which agreed well with the remediation times estimated using the attenuation rates calculated for the site.
A New Multilevel Ground Water Monitoring System Using Multichannel Tubing
Authors: Einarson Murray D. , Cherry John A.
Published: February 2007

A new multilevel ground water monitoring system has been developed that uses custom‐extruded flexible 1.6‐inch (4.1 cm) outside‐diameter (O.D.) multichannel HOPE tubing (referred to as Continuous Multichannel Tubing or CMT) to monitor as many as seven discrete zones within a single borehole in either unconsolidated sediments or bedrock. Prior to inserting the tubing in the borehole, ports are created that allow ground water to enter six outer pie‐shaped channels (nominal diameter = 0.5 inch [1.3 cm]) and a central hexagonal center channel (nominal diameter = 0.4 inch [1 cm]) at different depths, facilitating the measurement of depth‐discrete piezometric heads and the collection of depth‐discrete ground water samples. Sand packs and annular seals between the various monitored zones can be installed using conventional tremie methods. Alternatively, bentonite packers and prepacked sand packs have been developed that are attached to the tubing at the ground surface, facilitating precise positioning of annular seals and sand packs. Inflatable rubber packers for permanent or temporary installations in bedrock aquifers are currently undergoing site trials. Hydraulic heads are measured with conventional water‐level meters or electronic pressure transducers to generate vertical profiles of hydraulic head. Ground water samples are collected using peristaltic pumps, small‐diameter bailers, inertial lift pumps, or small‐diameter canister samplers.

For monitoring hydrophobic organic compounds, the CMT tubing is susceptible to both positive and negative biases caused by sorption, desorption, and diffusion. These biases can be minimized by: (1) purging the channels prior to sampling, (2) collecting samples from separate 0.25‐inch (0.64 cm) O.D. Teflon sampling tubing inserted to the bottom of each sampling channel, or (3) collecting the samples downhole using sampling devices positioned next to the intake ports. More than 1000 CMT multilevel wells have been installed in North America and Europe to depths up to 260 feet (79 m) below ground surface. These wells have been installed in boreholes created in unconsolidated sediments and bedrock using a wide range of drilling equipment, including sonic, air rotary, diamond‐bit coring, hollow‐stem auger, and direct push. This paper presents a discussion of three field trials of the system, demonstrating its versatility and illustrating the type of depth‐discrete data that can be collected with the system.
Pulsed Air Sparging in Aquifers Contaminated with Dense Nonaqueous Phase Liquids
Authors: Heron Gorm , Gierke John S. , Faulkner Barton , Mravik Susan , Wood Lynn , Enfield Carl G.
Published: February 2007

Air sparging was evaluated for remediation of tetrachloroethylene (PCE) present as dense nonaqueous phase liquid (DNAPL) in aquifers. A two‐dimensional laboratory tank with a transparent front wall allowed for visual observation of DNAPL mobilization. A DNAPL zone 50 cm high was created, with a PCE pool accumulating on an aquitard. Detailed process control and analysis yielded accurate mass balances and insight into the mass‐transfer limitations during air sparging.

Initial PCE recovery rates were high, corresponding to fast removal of residual DNAPL within the zone influenced directly by air channels. The vadose zone DNAPL was removed within a few days, and the recovery in the extracted soil vapors decreased to low values. Increasing the sparge rate and pulsing the air injection led to improved mass recovery, as the pulsing induced water circulation and increased the DNAPL dissolution rate. Dissolved PCE concentrations both within and outside the zone of air channels were affected by the pulsing. Inside the sparge zone, aqueous concentrations decreased rapidly, matching the declining effluent PCE flux. Outside the sparge zone, PCE concentrations increased because highly contaminated water was pushed away from the air injection point.

This overall circulation of water may lead to limited spreading of the contaminant, but accelerated the time‐weighted average mass removal by 40% to 600%, depending on the aggressiveness of the pulsing. For field applications, pulsing with a daily or diurnal cycling time may increase the average mass removal rate, thus reducing the treatment time and saving in the order of 40% to 80% of the energy cost used to run the blowers. However, air sparging will always fail to remove DNAPL pools located below the sparge point because the air will rise upward from the top of a screen, unless very localized geological layers force the air to migrate horizontally. Unrecognized presence of DNAPL at chlorinated solvent sites residual and pools could potentially hamper success of air sparging cleanups, since the presence of small DNAPL pools, ganglia or droplets can greatly extend the treatment time.
Recovery of Coal Tar and Creosote from Porous Media: The Influence of Wettability
Authors: Hugaboom Daniel A. , Powers Susan E.
Published: February 2007

The recovery of coal tar or creosote, which are dense nonaqueous phase liquids (DNAPLs), from the subsurface has been used as a means of site remediation at several former manufactured‐gas plant sites and wood‐treating facilities. Surface‐active components in these complex DNAPL can have acid/base and surfactant characteristics that can significantly affect the wettability in these systems, with a reversal to DNAPL wetting at low pHs. These changes in wettability as a function of pH were employed to evaluate their significance on waterflooding efficiency in one‐dimensional soil columns. The use of pH as a means of controlling wettability resulted in identical density and viscosity properties between the water‐and DNAPL‐wet conditions. At some of the higher pHs, the interracial tension changed as well as the wettability. Maintaining a constant dimensionless capillary number was used to minimize the effect of this variable. DNAPL saturations remaining in the DNAPL‐wet systems after waterflooding ranged from 38% to 47%. Significantly lower final DNAPL saturations were achieved for water‐wetting systems (15% to 30%).
Fate of Pharmaceuticals During Ground Water Recharge
Authors: Drewes Jörg E. , Heberer Thomas , Rauch Tanja , Reddersen Kirsten
Published: February 2007

Pharmaceuticals and personal care products (PPCPs) have recently been detected in the aquatic environment. Many studies have identified domestic waste water discharge as the source for detectable concentrations of PPCPs in surface water. PPCPs are a concern for the aquatic environment when production and use are sufficiently large and physicochemical properties are appropriate. Hydrophilic PPCPs present in surface water or waste water may also affect ground water quality where water is used to recharge ground water. However, less is known about how efficiently PPCPs are removed during percolation through the subsurface. The scope of this study was to examine the fate of selected PPCPs during ground water recharge at two water reuse sites where secondary and tertiary treated waste water is used for subsequent ground water recharge. The ground water recharge sites selected differ in aboveground treatment and geohydrological settings. The selected pharmaceutials represent blood lipid regulators, analgesics/anti‐inflammatories, blood viscosity agents, and antiepileptics. Organic iodine was used as a surrogate parameter for X‐ray contrast agents. Composite samples of treated waste water and from ground water monitoring wells were collected and analyzed for Pharmaceuticals using gas chromatography with mass spectroscopic detection.

The study revealed that the stimulant caffeine, analgesic/anti‐inflammatory drugs such as diclofenac, ibuprofen, ketoprofen, naproxen, and fenoprofen, and blood lipid regulators such as gemfibrozil were efficiently removed to concentrations near or below the detection limit of the analytical method after retention times of less than six months during ground water recharge. The antiepileptics carbamazepine and primidone were not removed during ground water recharge under either anoxic saturated or aerobic unsaturated flow conditions during travel times of up to eight years. Organic iodine showed a partial removal only under anoxic, saturated conditions as compared to aerobic conditions and persisted in the recharged ground water.
A Comparison of Benzene and Toluene Plume Lengths for Sites Contaminated with Regular vs. Ethanol‐Amended Gasoline
Authors: Ruiz‐Aguilar G.M.L , O'Reilly K. , Alvarez P.J.J.
Published: February 2007

This article describes various statistical analyses of plume‐length data to evaluate the hypothesis that the presence of ethanol in gasoline may hinder the natural attenuation of hydrocarbon releases. Plume dimensions were determined for gasoline‐contaminated sites to evaluate the effect of ethanol on benzene and toluene plume lengths. Data from 217 sites in Iowa (without ethanol; set 1) were compared to data from 29 sites in Kansas that were contaminated by ethanol‐amended gasoline (10% ethanol by volume; set 2). The data were log‐normally distributed, with mean benzene plume lengths (± standard deviation) of 193 ± 135 feet for set 1 and 263 ± 103 feet for set 2 (36% longer). The median lengths were 156 feet and 263 feet (69% longer), respectively. Mean toluene plume lengths were 185± 131 feet for set 1 and 211 ±99 feet for set 2 (14% longer), and the median lengths were 158 feet and 219 feet (39% longer), respectively. Thus, ethanol‐containing BTEX plumes were significantly longer for benzene (p < 0.05), but not for toluene. A Wilcoxon signed rank test showed that toluene plumes were generally shorter than benzene plumes, which suggests that toluene was attenuated to a greater extent than benzene. This trend was more pronounced for set 2 (with ethanol), which may reflect that benzene attenuation is more sensitive to the depletion of electron acceptors caused by ethanol degradation. These results support the hypothesis that the presence of ethanol in gasoline can lead to longer benzene plumes. The importance of this effect, however, is probably site‐specific, largely depending on the release scenario and the available electron acceptor pool.
Evaluation of the Johnson and Ettinger Model for Prediction of Indoor Air Quality
Authors: Hers Ian , Zapf‐Gilje Reidar , Johnson Paul C. , Li Loretta
Published: February 2007

Screening level models are now commonly used to estimate vapor intrusion for subsurface volatile organic compounds (VOCs). Significant uncertainty is associated with processes and models and, to date, there has been only limited field‐based evaluation of models for this pathway. To address these limitations, a comprehensive evaluation of the Johnson and Ettinger (J&E) model is provided through sensitivity analysis, comparisons of model‐predicted to measured vapor intrusion for 11 petroleum hydrocarbon and chlorinated solvent sites, and review of radon and flux chamber studies. Significant intrusion was measured at five of 12 sites with measured vapor attenuation ratios (αm's) (indoor air/source vapor) ranging from ∼1 × 10−6 to 1 × 10−4. Higher attenuation ratios were measured for studies using radon, inert tracers, and flux chambers; however, these ratios are conservative owing to boundary conditions and tracer properties that are different than those at most VOC‐contaminated sites. Reasonable predictions were obtained using the J&E model with comparisons indicating that model‐predicted vapor attenuation ratios (αp's) were on the same order, or less than the αm's. For several sites, the (m were approximately two orders of magnitude less than the a 's indicating that the J&E model is conservative in these cases. The model comparisons highlight the importance in using appropriate input parameters for the J&E model. The regulatory implications associated with use of the J&E model to derive screening criteria are also discussed.
In Situ Abiotic Detoxification and Immobilization of Hexavalent Chromium
Authors: Khan Faruque A. , Puts Robert W.
Published: February 2007

Detailed site characterization data from the former electroplating shop at the U.S. Coast Guard Air Support Center, Elizabeth City, North Carolina, suggested that the elevated Cr(VI) in the capillary fringe area had contaminated the ground water at the site. Most of the mobile Cr(VI) is present in the capillary fringe zone of the aquifer under an oxidizing environment. Current literature suggests that the reduction of Cr(VI) to Cr(III) through in situ redox manipulation in the presence of a reductant is an innovative technique for remediating chromate‐contaminated sediments and ground water. The objective of this study was to evaluate the effectiveness of sodium dithionite in creating a reductive environment to remediate Cr(VI) present in soil. Sodium dithionite, a strong reductant, was injected into a small area of the vadose zone where elevated Cr(VI) was identified. Several striking changes observed in the target zone during the post‐injection monitoring periods include a significant decrease in Eh(SHE), as much as ∼700 mV, absence of dissolved oxygen for 48 weeks, and the increase of Fe(II) concentrations. Results indicated that the in situ remedial treatment of Cr(VI) in the capillary fringe area was effective and consequently the concentration of Cr(VI) in ground water dropped below the MCLG level. This research demonstrated the effectiveness of in situ abiotic remediation by reducing Cr(VI) concentrations, mobility, and toxicity in soils and ground water within a short period of time. Therefore, sodium dithionite would be a feasible and cost‐effective option for a full‐scale remedial approach for the contaminated site at the U.S. Coast Guard Facility.
Do Pharmaceuticals, Pathogens, and Other Organic Waste Water Compounds Persist When Waste Water Is Used for Recharge?
Authors: Cordy Gail E. , Duran Norma L. , Bouwer Herman , Rice Robert C. , Furlong Edward T. , Zaugg Steven D. , Meyer Michael T. , Barber Larry B. , Kolpin Dana W.
Published: February 2007

A proof‐of‐concept experiment was devised to determine if pharmaceuticals and other organic waste water compounds (OWCs), as well as pathogens, found in treated effluent could be transported through a 2.4 m soil column and, thus, potentially reach ground water under recharge conditions similar to those in arid or semiarid climates. Treated effluent was applied at the top of the 2.4 m long, 32.5 cm diameter soil column over 23 days. Samples of the column inflow were collected from the effluent storage tank at the beginning (Tbegin) and end (Tend) of the experiment, and a sample of the soil column drainage at the base of the column (Bend) was collected at the end of the experiment. Samples were analyzed for 131 OWCs including veterinary and human antibiotics, other prescription and nonprescription drugs, widely used household and industrial chemicals, and steroids and reproductive hormones, as well as the pathogens Salmonella and Legionella. Analytical results for the two effluent samples taken at the beginning (Tbegin) and end (Tend) of the experiment indicate that the number of OWCs detected in the column inflow decreased by 25% (eight compounds) and the total concentration of OWCs decreased by 46% while the effluent was in the storage tank during the 23‐day experiment. After percolating through the soil column, an additional 18 compounds detected in Tend (67% of OWCs) were no longer detected in the effluent (Bend) and the total concentration of OWCs decreased by more than 70%. These compounds may have been subject to transformation (biotic and abiotic), adsorption, and (or) volatilization in the storage tank and during travel through the soil column. Eight compounds—carbamazapine; sulfamethoxazole; benzophenone; 5‐methyl‐1H‐benzotriazole; N, N‐diethyltoluamide; tributylphosphate; tri(2‐chloroethyl) phosphate; and cholesterol—were detected in all three samples indicating they have the potential to reach ground water under recharge conditions similar to those in arid and semiarid climates. Results from real‐time polymerase chain reactions demonstrated the presence of Legionella in all three samples. Salmonella was detected only in Tbegin, suggesting that the bacteria died off in the effluent storage tank over the period of the experiment. This proof‐of‐concept experiment demonstrates that, under recharge conditions similar to those in arid or semiarid climates, some pharmaceuticals, pathogens, and other OWCs can persist in treated effluent after soil‐aquifer treatment.
Analysis of Endocrine Disrupting Steroids: Investigation of Their Release into the Environment and Their Behavior During Bank Filtration
Authors: Zuehlke Sebastian , Duennbier Uwe , Heberer Thomas , Fritz Birgit
Published: February 2007

A reliable and sensitive analytical method for the determination of estrone (E1), 17β‐estradiol (E2), and the synthetic hormone 17α‐ethinylestradiol (EE2) has been established. Samples are concentrated using automated solid‐phase extraction and analysis is performed by liquid chromatography with detection by tandem mass spectrometry. Recoveries of all analytes were between 93% and 107%, and limits of quantification (LOQs) between 0.1 and 0.4 ng/L for purified sewage, and surface, ground, and drinking water, and between 1 and 2 ng/L in case of raw sewage. For the investigation of estrogen release into the environment and its behavior during sewage and surface water treatment, and during ground water recharge, samples from municipal waste water treatment plants (WWTPs), a surface water treatment plant, a bank filtration site, and a ground water enrichment (GWE) pond were analyzed. El was found in the raw waste water with an average concentration of 157 ng/L, whereas E2 and EE2 were found with mean concentrations of only 18 and 9 ng/L, respectively. Sewage treatment by municipal WWTPs affected a removal of EE2 (76%), El (92%), and E2 (94%). In the investigated surface water of Berlin, only E1 could be detected at concentrations around or below 1 ng/L. E2 and EE2 were not present in the Berlin surface water above the LOQ of 0.2 ng/L, respectively. Surface water treatment also leads to a significant removal of E1 (> 80%). In the ground water samples from the GWE site near Lake Tegel, only a few samples contained detectable concentrations of E1. These samples were collected from a shallow monitoring well located very close to the bank of the pond. Even a short distance between the bank and observation wells led to concentrations of El below the LOQ showing the potential of ground water recharge systems for the retention of estrogenic steroids depending on the environmental setting.
Estrogenic Activity and Volume Fraction of Waste Water Origin in Monitoring Wells Along the Santa Cruz River, Arizona
Authors: Quanrud David M. , Quast Konrad , Conroy Otakuye , Karpiscak Martin M. , Gerba Charles P. , Lansey Kevin E. , Ela Wendell P. , Arnold Robert G.
Published: February 2007

The fate of estrogenic activity in waste water effluent was examined during surface transport and incidental recharge along the Santa Cruz River in Pima County, Arizona. Based on measurement of boron isotopes, the fractional contribution of reclaimed water in surface waters and ground water wells proximate to the river was determined for a contemporary sample set. Estrogenic activity decreased by −60% over the 25 mi length of the river below effluent discharge points in Tucson. In ground water samples obtained from monitoring wells that are proximate to the Santa Cruz River, both dissolved organic carbon (p= 0.0003) and estrogenic activity (p= 3 × 10−6) were highly correlated to fractional waste water content. Results indicate that proximate ground water quality is sensitive to incidental recharge of reclaimed water in the Santa Cruz River bed. In a few locations, little attenuation of estrogenic activity was apparent during percolation of effluent in the river channel to well withdrawal points.
Fate of Steroidal Hormones During Soil‐Aquifer Treatment
Authors: Mansell Jessica , Drewes Jörg E.
Published: February 2007

There is increasing concern that endocrine disrupting compounds such as steroidal hormones present in treated waste water effluents can affect ground water quality where waste water is used to recharge local ground water. Little is known how efficiently steroidal hormones are removed or transformed during percolation through the subsurface. The scope of this study was to examine the fate of hormones during soil‐aquifer treatment (SAT) leading to ground water recharge in controlled laboratory soil‐column studies and at two water reuse field sites where treated waste water is fed to ground water recharge basins. The selected steroidal hormones represented estrogens (17β‐estradiol and estriol) and androgens (testosterone). Composite samples of treated waste water and from ground water monitoring wells were collected and analyzed for steroidal hormones using enzyme‐linked immunosorbent assays. The study revealed that the mobility of the selected hormones in subsurface systems was low, and estriol and testosterone were both not detected (< 0.6 ng/L) in ground water monitoring wells or shallow lysimeters representing water samples after 1.5 m of travel through porous media. 17β‐estradiol, however, was consistently detected at concentrations < 2 ng/L in monitoring wells after travel of 1.5 m through porous media. Results from field sites that have been operational for more than 13 years indicated no breakthrough of the target compounds in ground water samples collected downstream of the surface spreading operation. These findings were confirmed by controlled laboratory studies simulating SAT in soil‐column experiments. It appeared that the majority of attenuation was due to adsorption of the three target compounds to the porous media matrix, and additional attenuation to below the detection limit occurred due to the presence of bioactivity regardless of dominating redox conditions (aerobic vs. anoxic) or the type of organic carbon matrix present (hydrophobic acids, hydrophilic carbon vs. colloidal carbon).
Pharmaceuticals and Other Organic Waste Water Contaminants Within a Leachate Plume Downgradient of a Municipal Landfill
Authors: Barnes Kimberlee K. , Christenson Scott C. , Kolpin Dana W. , Focazio Michael J. , Furlong Edward T. , Zaugg Steven D. , Meyer Michael T. , Barber Larry B.
Published: February 2007

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,N‐diethyltoluamide (DEBT 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.
CETACEAN OCCURRENCE PATTERNS IN THE AMUNDSEN AND SOUTHERN BELLINGSHAUSEN SEA SECTOR, SOUTHERN OCEAN
Authors: Ainley David G. , Dugger Katie M. , Toniolo Viola , Gaffney Ian
Published: February 2007

Abstract

We conducted 239.5 h and 3,494 km of cetacean surveys in the Amundsen and Bellingshausen seas, from 15 February to 31 March 1994; most of the area, the large portion of which was ice covered, had never before nor has it since been surveyed for cetaceans, even to the date when this paper was prepared (2006). Logistic regression and an information‐theoretic approach related the occurrence of Antarctic minke whales Balaenoptera bonaerensis (the most abundant species) to whether we were in open‐ or pack‐ice‐covered pelagic or neritic waters, in or out of the marginal ice zone (MIZ), and north or south of the Antarctic Circumpolar Current southern boundary. Other variables included date and distance to the MIZ and shelfbreak front. Statistical analysis showed that the probability of sighting a minke, as well as killer whale—but not the case for an index to whale density—was related to the proximity of coastal polynyas in early autumn, switching offshore to the MIZ once waters within the pack began to freeze persistently later in the season. Probability of detection was higher with distance into the MIZ. Supporting these findings, the density index was strongly related to ice concentration in an inverse relationship. The strong relationship to polynyas and the MIZ indicate that sea‐ice divergence altered by decadal or longer‐term climate change, as described in the recent literature, could well affect any apparent, long‐term trends evident in this species' abundance if surveyed only in open or near‐to‐ice waters. We speculate on how the minke whale's pagophilic nature (1) could have been encouraged by large‐scale industrial whaling and by competition with species more characteristic of open waters and the outer MIZ, and (2) may have protected the population somewhat during industrial whaling resulting in the much greater abundance of this species now compared to other targeted species.
Hypoxic preconditioning attenuates lipopolysaccharide‐induced oxidative stress in rat kidneys
Authors: Yang Chih‐Ching , Ma Ming‐Chieh , Chien Chiang‐Ting , Wu Ming‐Shiou , Sun Wan‐Kuan , Chen Chau‐Fong
Published: February 2007

Chronic hypoxic (CH) preconditioning reduces superoxide‐induced renal dysfunction via the upregulation of superoxide dismutase (SOD) activity and contents. Endotoxaemia reduces renal antioxidant status. We hypothesize that CH preconditioning might protect the kidney from subsequent endotoxaemia‐induced oxidative injury. Endotoxaemia was induced by intraperitoneal injection of lipopolysaccharide (LPS; 4 mg kg−1) in rats kept at sea level (SL) and rats with CH in an altitude chamber (5500 m for 15 h day−1) for 4 weeks. LPS enhanced xanthine oxidase (XO) and gp91phox (catalytic subunit of NADPH oxidase) expression associated with burst amount of superoxide production from the SL kidney surface and renal venous blood detected by lucigenin‐enhanced chemiluminescence. LPS induced a morphologic‐independent renal dysfunction in baseline and acute saline loading stages and increased renal IL‐1β protein and urinary protein concentration in the SL rats. After 4 weeks of induction, CH significantly increased Cu/ZnSOD, MnSOD and catalase expression (16 ± 17, 128 ± 35 and 48 ± 21, respectively) in renal cortex, and depressed renal cortex XO (44 ± 16%) and renal cortex (20 ± 9%) and medulla (28 ± 11%) gp91phox when compared with SL rats. The combined effect of enhanced antioxidant proteins and depressed oxidative proteins significantly reduced LPS‐enhanced superoxide production, renal XO and gp91phox expression, renal IL‐1β production, and urinary protein level. CH also ameliorated LPS‐induced renal dysfunction in the baseline and acute saline loading periods. We conclude that CH treatment enhances the intrarenal antioxidant/oxidative protein ratio to overcome endotoxaemia‐induced reactive oxygen species formation and inflammatory cytokine release.