bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cyclodextrin‐Enhanced Vertical Flushing of a Trichloroethene Contaminated Aquifer
Authors: Blanford W.J. , Barackrnan M.L. , Boing T.B. , Klingel E.J. , Johnson G.R. , Brusseau M.L. 
Published: February 2007

AbstractPilot‐scale testing of an innovative ground water remediation technology was conducted in a source zone of a trichloroethene‐contaminated Superfund site in Tucson, Arizona. The technology is designed to enhance the removal of low‐solubility organic contaminants from heterogeneous sedimentary aquifers by using a dual‐screened vertical circulation well to inject and extract solutions containing a complexing sugar (hydroxypropyl‐beta‐cyclodextrin (HPCD]). Prior to initiating the pilot test, tracer tests were conducted to determine hydraulic characteristics of the vertical flow field and to evaluate trichloroethene‐elution behavior during water flushing. The pilot test involved injecting approximately 4 m3 of a 20% HPCD solution into the upper screened interval of the well and extracting from the lower screened interval. The results of the pilot test indicate that the cyclodextrin solution increased the rate of trichloroethene removal from the aquifer. The concentrations of trichloroethene in the ground water extracted from the lower screened interval of the well increased by a factor of three (∼750 μg/L) in the presence of the cyclodextrin pulse, compared to concentrations obtained during previous water flushing (∼250 μg/L). Furthermore, the concentration of trichloroethene in water collected from the circulation well under static conditions was reduced to 6% of the levels measured prior to the test.
DNAPL to LNAPL Transitions During Horizontal Cosolvent Flooding
Authors: Roeder Eberhard , Falta Ronald W. , Lee Cindy M. , Coates John T. 
Published: February 2007

AbstractCosolvent flooding is a technology with the potential to remove nonaqueous phase liquid (NAPL) sources from the subsurface. It can be used to initiate separate phase mobilization, which allows removal of NAPL within very few pore volumes. Mobilization may result in a sinking DNAPL bank during horizontal flooding of NAPLs denser than water. Reversal of phase density difference between aqueous and DNAPL phases could potentially avoid this downward migration of mobilized DNAPLs. We achieved phase density difference reversal and made DNAPLs float using two components in the cosolvent flooding solution. A low‐density cosolvent partitions preferentially into the DNAPL and swells it, which causes a reduction in density of the DNAPL and reversal of the density difference between the NAPL and aqueous phases. A highdensity additive that remains in the aqueous phase allows the cosolvent flooding solution overall to have a density greater than that of water and permits control of the flooding instability. This study focused on tert‐butanol as the swelling cosolvent and tetrachloroethylene as the contaminant. In batch tests with sucrose and glycerol as dense additives, phase density difference reversal occurred. To investigate the applicability of phase density difference reversal as a remediation technology, horizontal column and sandbox experiments were performed. These experiments demonstrated the occurrence of phase density difference reversal and effective remediation in horizontal cosolvent floods.
The Effect of Air Bubbles and Headspace on the Aqueous Concentrations of Volatile Organic Compounds in Sampling Vials
Authors: Nadim Farhad , Liu Shili , Hoag George E. 
Published: February 2007

AbstractThe presence of headspace and air bubbles in volatile organic analysis sampling vials lowers the actual aqueous concentration of these compounds due to the partitioning of solutes into the gaseous phase. This could make the sample invalid for analysis.In this work, the effects of air bubbles and headspace on the aqueous concentration of 60 volatile organic compounds listed in U.S.Environmental Protection Agency (U.S. EPA) Method 8260 were evaluated experimentally and theoretically. The results showed that for air to water ratios of 1 to 20 and less, there was no significant effect on the aqueous concentrations of target organic solutes in the sampling vials. When the air to water ratio was increased to 1 to 10, the recovery rates of four organic compounds were lower than the control. Laboratory experiments on sampling vials showed that the presence of air bubbles or headspace with the volumetric air to water ratios of 1 to 20 and less do not produce any significant effect on the original concentrations for most targeted volatile organic compounds.The experimental results also indicated that in 40 mL sampling vials with headspace range of 2 to 8 mL, the recovery rates of most volatile organic compounds with high values of Henry's law constant (> 0.01 Atm m3/mol. at 25°C) were larger than the calculated rates.
Biodegradation of Creosote Compounds: Comparison of Experiments at Different Scales
Authors: Broholm Kim , Arvin Erik 
Published: February 2007

AbstractThis paper compares the results of biodegradation experiments with creosote compounds performed at different scales. The experiments include field observations, field experiments, large‐scale intact laboratory column experiments, model fracture experiments, and batch experiments. Most of the experiments were conducted with till or ground water from the field site at Ringe on the island of Funen. Although the experiments were conducted on different scales, they revealed that some phenomena—e.g., an extensive biodegradation potential of several of the creosote compounds, the inhibitory influence of the pyrroles on the biodegradation of benzene, and the biodegradation of benzothiophene occurs only in the presence of a primary substrate. The experiments show that some biodegradation processes of organic compounds may be common to different microorganisms.
Long‐Term Ground Water Quality Impacts from the Use of Hexazinone for the Commercial Production of Lowbush Blueberries
Authors: Keizer Jonathan P. , MacQuarrie Kerry T.B. , Milburn Paul H. , McCully Kevin V. , King Russ R. , Embleton E. Jean 
Published: February 2007

AbstractLowbush blueberries, native to eastern Canada and Maine, are an important economic crop in these areas. Herbicides containing the active ingredient hexazinone are commonly applied to blueberry fields, and there is a high frequency of detection of relatively low concentrations of hexazinone in domestic wells located close to areas of lowbush blueberry production. The objective of this study was to determine the long‐term impacts from hexazinone‐based herbicide use on ground water quality in the immediate growing areas.Physical and chemical hydrogeologic data were collected for an outwash sand and gravel aquifer in southwestern New Brunswick, Canada. The majority of the land overlying the aquifer is devoted to lowbush blueberry production. Twenty‐one nested monitoring wells were sampled for hexazinone and hexazinone metabolites over a four‐year period. Hexazinone was consistently detected at values of 1 to 8 parts per billion (ppb) in all but two of these wells, one that is upgradient of herbicide applications, and one that is downgradient with anoxic conditions. Hexazinone metabolites B and A1 were also detected in all but two of the 21 wells at values ranging from 0.5 to 2.5 ppb. The hexazinone and metabolite data suggest both aerobic and anaerobic degradation of hexazinone. Complete degradation of hexazinone appears to occur only in the one downgradient well exhibiting anoxic ground water conditions. Concentrations of hexazinone and its metabolites in the ground water were essentially constant over the four‐year period.
Bacterial Production Stimulated Across the Zone of Influence of a Ground Water Circulation Well in a BTEX‐Contaminated Aquifer
Authors: Montgomery Michael T. , Spargo Barry J. , Mueller James G. , Coffin Richard B. , Smith David C. , Boyd Thomas J. 
Published: February 2007

AbstractBenzene, toluene, ethylbenzene, and xylene (BTEX) hydrocarbons are typically the most abundant carbon source for bacteria in gasoline‐contaminated ground water. In situ bioremediation strategies often involve stimulating bacterial heterotrophic production in an attempt to increase carbon demand of the assemblage. This may, in turn, stimulate biodegradation of contaminant hydrocarbons. In this study, ground water circulation wells (GCWs) were used as an in situ treatment for a fuel‐contaminated aquifer to stimulate bacterial production, purportedly by increasing oxygen transfer to the subsurface, circulating limiting nutrients, enhancing bioavailability of hydrocarbons, or by removing metabolically inhibitory volatile organics. Bacterial production, as measured by rates of bacterial protein synthesis, was stimulated across the zone of influence (ZOI) of a series of GCWs. Productivity increased from ∼102 to >105 ng C/L hour across the ZOI, suggesting that treatment stimulated overall biodegradation of carbon sources present in the ground water. However, even if BTEX carbon met all bacterial carbon demand, biodegradation would account for <4.3% of the total estimated BTEX removed from the ground water. Although bacterial productivity measurements alone cannot prove the effectiveness of in situ bioremediation, they can estimate the maximum amount of contaminant that may be biodegraded by a treatment system.
Used Motor Oil as a Source of MTBE, TAME, and BTEX to Ground Water
Authors: Baker Ronald J. , Best Eric W. , Baehr Arthur L 
Published: February 2007

AbstractMethyl tert‐butyl ether (MTBE), the widely used gasoline oxygenate, has been identified as a common ground water contaminant, and BTEX compounds (benzene, toluene, ethylbenzene, and xylenes) have long been associated with gasoline spills. Because not all instances of ground water contamination by MTBE and BTEX can be attributed to spills or leaking storage tanks, other potential sources need to be considered. In this study, used motor oil was investigated as a potential source of these contaminants. MTBE in oil was measured directly by methanol extraction and gas chromatography using a flame ionization detector (GC/FID). Water was equilibrated with oil samples and analyzed for MTBE, BTEX, and the oxygenate tert‐amyl methyl ether (TAME) by purge‐ and‐trap concentration followed by GC/FID analysis. Raoult's law was used to calculate oil‐phase concentrations of MTBE, BTEX, and TAME from aqueous‐phase concentrations. MTBE, TAME, and BTEX were not detected in any of five new motor oil samples, whereas these compounds were found at significant concentrations in all six samples of the used motor oil tested for MTBE and all four samples tested for TAME and BTEX. MTBE concentrations in used motor oil were on the order of 100 mg/L. TAME concentrations ranged from 2.2 to 87 mg/L. Concentrations of benzene were 29 to 66 mg/L, but those of other BTEX compounds were higher, typically 500 to 2000 mg/L.
A Simple Model of Soil‐Gas Concentrations Sparged into an Unlined Unsaturated Zone
Authors: Ostendorf David W. , Hinlein Erich S. , Lutenegger Alan J. , Tehrany Pierre S. 
Published: February 2007

AbstractWe derive an analytical model of soil‐gas contamination sparged into an imlined unsaturated zone. A nonaqueous phase liquid (NAPL) source lies in the capillary fringe, with an exponential sparge constant within the radius of influence and a constant ambient evaporation rate beyond. Advection, diffusion, and dispersion govern the conservative soil‐gas response, expressed as a quasi‐steady series solution with radial Bessel and hyperbolic vertical dependence. Simulations suggest that sparged contamination initially spreads beyond the radius of influence down a negative gradient. This gradient eventually reverses, leading to a subsequent influx of ambient contamination. Soil‐gas concentrations accordingly reflect slowly varying source conditions as well as slowly varying diffusive transport through the radius of influence. The two time scales are independent: One depends on NAPL, airflow, and capillary fringe characteristics, the other on soil moisture, gaseous diffusivity, and unsaturated zone thickness. The influx of ambient contamination generates an asymptotic soil‐gas concentration much less than the initial source concentration. The simple model is applied to a pilot‐scale sparging study at Plattsburgh Air Force Base in upstate New York, with physically plausible results.
An Environmentally Friendly Decontamination Protocol for Ground Water Sampling Devices
Authors: Parker Louise V. , Ranney Thomas A. 
Published: February 2007

AbstractSeveral detergent‐washing/air‐drying decontamination protocols were tested to determine their ability to remove residual contamination from two types of ground water sampling devices. We tested a relatively simply constructed device, a bailer, and a much more complex, and theoretically more difficult to decontaminate, bladder pump. The devices were decontaminated after sampling ground water that was contaminated with organics that varied in their hydrophobic nature and propensity to be sorbed by the materials in the devices. These studies showed that a hot‐detergent wash, hot‐water rinse, and hot‐air drying protocol was effective.
Laboratory Comparison of Polyethylene and Dialysis Membrane Diffusion Samplers
Authors: Ehlke Theodore A. , Imbrigiotta Thomas E. , Dale Jeffrey M. 
Published: February 2007

AbstractThe ability of diffusion samplers constructed from regenerated cellulose dialysis membrane and low density, lay flat polyethylene tubing to collect volatile organic compounds and inorganic ions was compared in a laboratory study. Concentrations of vinyl chloride, cis‐1, 2‐dichloroethene, bromochloromethane, trichloroethene, bromodichloromethane, and tetrachloroethene collected by both types of diffusion samplers reached equilibrium with the concentrations of these compounds in test solution within three days. Concentrations of bromide and iron collected by the dialysis membrane diffusion samplers reached equilibrium with the concentrations of these compounds in a test solution within three to seven days. No detectable concentrations of bromide or iron were found in polyethylene diffusion samplers even after 21 days. No measurable concentrations of aluminum, arsenic, barium, cadmium, chromium, iron, mercury, manganese, nickel, and lead, or sulfide, were leached out of dialysis membrane samplers over seven days. Compared with using a gas‐tight syringe to sample the diffusion sampler, clipping the bag and pouring the water sample into a sample vial resulted in only a small 6.2% average loss of volatile organic compounds. Dialysis membrane diffusion samplers offer promise for use in sampling ground water for inorganic constituents as well as volatile organic compounds.
Ground Water Recharge and Chemical Contaminants: Challenges in Communicating the Connections and Collisions of Two Disparate Worlds
Authors: Daughton Christian G. 
Published: February 2007

AbstractOur knowledge base regarding the presence and significance of chemicals foreign to the subsurface environment is large and growing — the papers in this volume serving as testament. However, complex questions with few answers surround the unknowns regarding the potential for environmental or human health effects from trace levels of xenobiotics in ground water, especially ground water augmented with treated waste water. Public acceptance for direct or indirect ground water recharge using treated municipal waste water (especially sewage) spans the spectrum from unquestioned embrace to outright rejection. In this paper, I detour around the issues most commonly discussed regarding ground water recharge and instead focus on some of the less‐recognized issues—those that emanate from the mysteries created at the many literal and virtual interfaces involved with the subsurface world. My major objective is to catalyze discussion that advances our understanding of the barriers to public acceptance of waste water reuse with its ultimate culmination in direct reuse for drinking. I pose what could be a key question as to whether much of the public's frustration or ambivalence in its decision‐making process for accepting, or rejecting, water reuse (for various purposes including personal use) emanates from fundamental inaccuracies, misrepresentation, or oversimplification of what water is and how it functions in the environment—just exactly what the water cycle is. These questions suggest it might behoove us to revisit some very elementary aspects of our science and how we are conveying them to the public.
Activity patterns, behavioural repertoires, and agonistic interactions of crayfish: A non-manipulative field study
Authors: Davis Karen , Huber Robert 
Published: February 2007

AbstractAgonistic behaviour of crayfish has been studied extensively in laboratory settings where pairs or groups of individuals are allowed to interact within an experimental arena. Crayfish agonistic behaviour within its natural context, however, has received little attention to date. The present, non-manipulative field study explored activity patterns, behavioural repertoires, and agonistic encounters of rusty crayfish (Orconectes rusticus) during the summer months using continuous, 24-hour, underwater video recording at a series of representative field sites. Following the filming, crayfish within the vicinity of the camera site were captured and measured. Individual densities were high, reaching a maximum of 68 individuals/m2 at some sites. Large crayfish predominantly inhabited deeper sections of the river and were mostly active at night, whereas small crayfish generally utilized the shallows and were active outside their burrows during day and dusk. Time outside their shelter was mainly used for feeding. Individuals frequently returned to the same shelter they had emerged from. Agonistic encounters were common events and generally occurred in the context of shelter acquisition or defense. Dyadic fighting progressed with escalating sequences of stereotyped aggressive acts. Furthermore, high intensities with unrestrained use of claws were seen in encounters between size-matched opponents. The results of this study allow us to root laboratory findings of crayfish aggression within a comprehensive, ethological framework and to consider ultimate consequences for individual fighting decisions and strategies.
Carotenoid-based plumage coloration and aggression during molt in male house finches
Authors: Medina-Jerez William , Adams Heather , McGraw Kevin 
Published: February 2007

AbstractBirds often use colorful traits to mediate resource competitions, and typically individuals with bright or large patches of color are more competitive than or dominant to those with drab or small color patches. Male House Finches (Carpodacus mexicanus) are an exception, however, as drab males tend to be more aggressive than bright males during the breeding season and in winter. One hypothesis for this 'negatively correlated handicap' is that drab male house finches, being comparatively sexually unattractive and in poor health and condition, have more to gain by elevating aggression and increasing access to food and pursuit of (especially extra-pair) mates. It would seem important then to test this hypothesis during the period of molt, when birds are actively acquiring the foods and carotenoid pigments that make them colorful and a time in which there is a clear link between plumage color and nutrition/health in this species. We conducted two captive dominance experiments with male House Finches from the southwestern United States (their native range) to examine the relationship between carotenoid-based plumage coloration and aggression during molt. In the first experiment, where birds exhibited their natural, currently growing plumage color, we found that drab males were significantly more aggressive than bright males. However, when plumage colors were manipulated with art markers in a second experiment, color display was no longer significantly predictive of agonistic outcomes. These results suggest that: (1) drab male dominance is not an artifact in eastern US populations and instead is a conserved property of native and non-native House Finches, (2) like in our previous studies in winter, plumage color is correlated with dominance but does not serve as a visual signal of social status in this species, and (3) drab males should have a competitive advantage over access to important carotenoid-rich foods during molt, but apparently do not become as colorful because they do not adequately locate carotenoid-rich foods or do not use them efficiently for energetic or health reasons, which are perhaps exacerbated by elevated testosterone levels.
Spatial association and social behaviour in zoo-living female ring-tailed coatis (Nasua nasua)
Authors: Aureli Filippo , Romero Teresa 
Published: February 2007

AbstractMost carnivore species are solitary and tend not to associate either with members of the same sex or with the opposite sex. In contrast, coati adult females and juveniles live in stable groups, called 'bands'. Coatis display complex cooperative behaviours, and their bands resemble primate female-bonded societies in various features. In this study we examined spatial association patterns among zoo-living ring-tailed coatis and related it to the patterns of affiliative and aggressive interactions. We found that coati females did not associate or interact with one another randomly. A cluster analysis on spatial association data revealed two main subunits, the size and composition of which were the same in two observation periods. Furthermore, the distribution of affiliative and aggressive interactions of the coatis reflected patterns of spatial association. Affiliative behaviour was more frequent between members of the same subunit than between members of different subunits, whereas aggressive interactions were more frequent between subunits than within subunits. We discuss the implications of these findings for coati social organisation suggesting that the two subunits may reflect the potential for subgroup formation and fission-fusion dynamics in wild populations.