bluuebunny/crossref_metadata_2025_split huggingface dataset:
Field Tracer Test for the Design of LNAPL Source Zone Surfactant Flushing
Authors: Robert Thomas , Martel Richard , Lefebvre René , Lauzon Jean‐Marc , Morin Annie 
Published: March 2018

AbstractA field tracer test was carried out in a light nonaqueous phase liquid (LNAPL) source zone using a well pattern consisting of one injection well surrounded by four extraction wells (5‐spot well pattern). Multilevel sampling was carried out in two observation wells located inside the test cell characterized by heterogeneous lithology. Tracer breakthrough curves showed relatively uniform flow within soil layers. A numerical flow and solute transport model was calibrated on hydraulic heads and tracer breakthrough curves. The model was used to estimate an average accessible porosity of 0.115 for the swept zone and an average longitudinal dispersivity of 0.55 m. The model was further used to optimize the relative effects of viscous forces versus capillary forces under realistic imposed hydraulic gradients and to establish optimal surfactant solution properties. Maximum capillary number (NCa) values between injection and extraction wells were obtained for an injection flow rate of 16 L/min, a total extraction flow rate of 20 L/min, and a surfactant solution with a viscosity of 0.005 Pa⋅s. The unconfined nature of the aquifer limited further flow rate or viscosity increases that would have led to unrealistic hydraulic gradients. An NCa range of 3.8 × 10−4 to 7.6 × 10−3 was obtained depending on the magnitude of the simulated LNAPL‐water interfacial tension reduction. Finally, surfactant and chase water slug sizing was optimized with a radial form of the simplified Ogata‐Banks analytical solution (Ogata and Banks 1961) so that injected concentrations could be maintained in the entire 5‐spot cell.
An Empirical Evaluation of the Influence of Ethanol on Natural Attenuation of Gasoline Constituents
Authors: O'Reilly Kirk , Espino Devine Catalina , Sihota Natasha , North Katharine 
Published: March 2018

AbstractSince the 1990s, questions have arisen as to whether the release of ethanol‐blended fuel will inhibit natural attenuation of other gasoline constituents in groundwater. This study evaluated the hypothesis that ethanol affects hydrocarbon attenuation and whether the use of ethanol‐blended fuel alters the applicability of monitored natural attenuation (MNA) as an approach for managing risks at fuel‐release sites. Groundwater data from California's GeoTracker database were used to compare attenuation of benzene, toluene, methyl tert‐butyl ether (MTBE), and tert‐butyl alcohol (TBA) at sites with and without detections of ethanol. Excel‐based tools were developed to conduct attenuation evaluations on thousands of wells simultaneously. Ethanol was detected at least once in 4.5% of the wells and 0.6% of the samples of which it was analyzed. The distribution of Mann‐Kendall concentration trend analysis results and first‐order attenuation rates were essentially the same at sites with or without ethanol detections. Median plume lengths were shorter at sites where ethanol had not been detected compared to sites where ethanol was detected (36 vs. 43 m for benzene; 36 vs. 42 m for toluene; 43 vs. 52 m for MTBE; and 44 vs. 59 m for TBA). However, the distribution of plume lengths was similar irrespective of ethanol concentrations, suggesting other factors may influence plume elongation. Finally, while anaerobic ethanol degradation can result in methane generation, the distributions of methane concentrations were the same at sites with and without ethanol detections. These results suggest that the use of ethanol‐blended fuel should not limit the application of MNA at most biodegrading fuel‐release sites.
Comparison of Oil Transmissivity Methods Using Bail‐Down Test Data
Authors: Palmier Cédric , Dodt Matthew , Atteia Olivier 
Published: March 2018

AbstractThis paper evaluates the results from three methods commonly used to estimate oil transmissivity: the modified Cooper solution (Beckett and Lyverse 2002), the modified Bouwer and Rice method (Kirkman 2013), and the modified Jacob and Lohman method (Huntley 2000). Determining the validity of oil transmissivity values is important (e.g., when used in extraction system design and operation) and not straightforward as these methods are based on different assumptions and boundary conditions and introduce different simplifying assumptions to allow for estimating oil drawdown. Data from 289 bail‐down tests performed during an oil remediation project were used in this evaluation. Analysis of these tests produced realistic transmissivity values and good correlation between these three methods, giving the authors confidence in the oil transmissivity values as this correlation is reflected across a significant number of data sets. Secondly, the nature of oil and water recharge to the wells interpreted from Kirkman's J‐ratio values largely validates the Huntley (2000) simplifying assumption that the potentiometric surface will be relatively constant during the test, allowing the use of the modified Bouwer and Rice method. Finally, the impact of oil extraction on measured oil thickness and estimated oil transmissivity was also assessed. The study showed a clear general decrease in both measured oil thicknesses and estimated oil transmissivity during the oil recovery project. However, measured oil thickness and estimated oil transmissivity are not clearly correlated, and, as a consequence, the range of decrease in one parameter does not allow any prediction of the range of decrease in the second parameter.
Utility of Compound‐Specific Isotope Analysis for Vapor Intrusion Investigations
Authors: Beckley Lila , McHugh Thomas , Philp Paul 
Published: March 2018

AbstractDifferent types of data can be collected to evaluate whether or not vapor intrusion is a concern at sites impacted with volatile organic compound (VOC) contamination in the subsurface. Typically, groundwater, soil gas, or indoor air samples are collected to determine VOC concentrations in the different media. Sample results are evaluated using a “multiple lines of evidence” approach to interpret whether vapor intrusion is occurring. Data interpretation is often not straightforward because of many complicating factors, particularly in the evaluation of indoor air. More often than not, indoor air sample results are affected by indoor or other background sources making interpretation of concentration‐based data difficult using conventional sampling approaches. In this study, we explored the practicality of compound‐specific isotope analysis (CSIA) as an additional type of evidence to distinguish between indoor sources and subsurface sources (i.e., vapor intrusion). We developed a guide for decision‐making to facilitate data interpretation and applied the guidelines at four different test buildings. To evaluate the effectiveness of the CSIA method for vapor intrusion applications, we compared the interpretation from CSIA to interpretations based on data from two different investigation approaches: conventional sampling and on‐site GC/MS analysis. Interpretations using CSIA were found to be generally consistent with the other approaches. In one case, CSIA provided the strongest line of evidence that vapor intrusion was not occurring and that a VOC source located inside the building was the source of VOCs in indoor air.
Cryogenic Core Collection (C3) from Unconsolidated Subsurface Media
Authors: Kiaalhosseini Saeed , Johnson Richard L. , Rogers Richard C. , Renno Maria Irianni , Lyverse Mark , Sale Thomas C. 
Published: March 2018

AbstractWe evaluated tools and methods for in situ freezing of cores in unconsolidated subsurface media. Our approach, referred to as cryogenic core collection (C3), has key aspects that include downhole circulation of liquid nitrogen (LN) via a cooling system, strategic use of thermal insulation to focus cooling into the core, and controlling LN back pressure to optimize cooling. Two cooling systems (copper coil and dual‐wall cylinder) are described. For both systems, the time to freeze a single 2.5‐foot (76‐cm) long by 2.5‐inch (63‐mm) diameter core is 5 to 7 min. Frozen core collection rates of about 30 feet/day (10 m/day) were achieved at two field sites, one impacted by petroleum‐based light nonaqueous phase liquids (LNAPLs) and the other by chlorinated solvents. Merits of C3 include (1) improved core recovery, (2) potential control of flowing sand, and (3) improved preservation of critical sediment attributes. Development of the C3 method creates novel opportunities to characterize sediment with respect to physical, chemical, and biological properties. For example, we were able to resolve water, LNAPL, and gas saturations above and below the water table. By eliminating drainage of water, gas and LNAPL saturations in the range of 6 to 23% and 1 to 3% of pore space, respectively, were measured in LNAPL‐impacted intervals below the water table.
Total Dissolved Gas Pressure Measurements for Assessing Contaminant Degradation Processes in Groundwater
Authors: Roy James W. , McLeod Heather C. , Suchy Martin , Smith James E. 
Published: March 2018

AbstractThe total dissolved gas pressure (PTDG) probe has been used in groundwater studies for over a decade, but rarely in assessing contaminant degradation, despite the many degradation reactions that produce or consume dissolved gases. Here we present three studies to demonstrate the application ofPTDGmeasurements to groundwater experiencing contaminant degradation, with discussion of its benefits and limitations. The first study is a pilot‐scale laboratory experiment simulating dissolved ethanol contamination of an anaerobic sand aquifer. Continuous monitoring ofPTDGshowed the rapid onset of microbial hydrocarbon degradation via denitrification and fermentation. The subsequent formation of a gas phase was revealed whenPTDGbegan mimicking the bubbling pressure (PG*; sum of hydrostatic and atmospheric pressure), fluctuating with atmospheric pressure. Some deviations ofPTDGabovePG* occurred also, which may hold promise for signalling substantial changes in the rate or type of degradation process (here, the onset of methanogenesis). In the second study, synoptic field measurements at a petroleum plume site demonstrated how elevatedPTDGcould identify wells with evidence of hydrocarbon degradation (denitrification and/or methanogenesis). And finally, combined field measurements ofdissolved oxygen (DO)andPTDGin monitoring wells of a nitrate‐contaminated aquifer (Abbottsford‐Sumas) revealed areas where denitrification was likely occurring. Limitations toPTDGuse identified in these studies included the masking of degradation processes by the presence of a gas phase, as when trapped following water table fluctuations or formed from rigorous degradation reactions, and confounded assessment ofPTDGpatterns from other natural or anthropogenic processes that can also influence groundwaterPTDG.
Bioaugmentation in a Well‐Characterized Fractured Rock DNAPL Source Area
Authors: Schaefer Charles E. , Lavorgna Graig M. , White Erin B. , Annable Michael D. 
Published: March 2018

AbstractA field demonstration was performed at Edwards Air Force Base to assess bioaugmentation for treatment of a well‐characterized tetrachloroethene (PCE) dense nonaqueous phase liquid (DNAPL) source area in fractured rock. Groundwater recirculation was employed to deliver remedial amendments, including bacteria, to facilitate reductive dechlorination and enhance DNAPL dissolution. An active treatment period of 9 months was followed by a 10‐month posttreatment rebound evaluation. Dechlorination daughter products were observed in both the shallow and deep fracture zones following treatment. In the shallow fracture zone, the calculated DNAPL mass removed was approximately equal to the DNAPL mass estimated using partitioning tracer testing, and no rebound in chlorinated ethenes or ethene was observed during the posttreatment period. A maximum DNAPL dissolution enhancement factor of 5 was observed in the shallow fracture zone. In the deep fracture zone, only approximately 45% of the DNAPL mass—as estimated via partitioning tracer testing—was removed and rebound in the total molar chlorinated ethenes + ethene was observed. The difference in behavior between the shallow and deep fracture zones was attributed to DNAPL architecture and the fracture flow field.
Performance Assessment of Pump‐and‐Treat Systems
Authors: Truex Michael , Johnson Chris , Macbeth Tamzen , Becker Dave , Lynch Kira , Giaudrone Dominic , Frantz, Aaron , Lee Hope 
Published: March 2018

AbstractPump‐and‐treat (P&T) is a widely applied remedy for groundwater remediation at many types of sites for multiple types of contaminants. Decisions regarding major changes in the remediation approach are an important element of environmental remediation management for a site using P&T. While existing guidance documents provide information on design, operation, and optimization for P&T systems, these documents do not provide specific technical guidance to support remedy decisions regarding when to transition to a new remedy or to initiate closure of the P&T remedy. A structured approach for P&T performance assessment was developed and is described herein, using analysis of three example P&T systems. These examples highlight key aspects of the performance assessment decision logic and represent assessment outcomes associated with optimizing the P&T system, transitioning from P&T to natural attenuation, and supplementing P&T with another technology to hasten transition to natural attenuation.
Interface Treatment of Petroleum Hydrocarbon‐impacted Lower Permeability Layers by Activated Sodium Persulfate to Reduce Emissions to Groundwater
Authors: Cavanagh Bridget A. , Wilson Sean T. , Johnson Paul C. , Daniels Eric J. 
Published: March 2018

AbstractNonaqueous phase liquid (NAPL)‐impacted lower permeability layers in heterogeneous media are difficult to fully remediate and can act as persistent sources of groundwater contamination through diffusive emissions to transmissive aquifer zones. This work investigated the benefits of partial remediation involving treatment focused near the high‐low permeability interface, with the performance metric being emissions reduction. A sequential base‐activated persulfate (S2O8
2−) delivery treatment strategy was studied in this work, involving 13–14 d deliveries of 10% w/w sodium persulfate (Na2S2O8) and 14–28 d deliveries of 19 g/L sodium hydroxide (NaOH). Treatment and control experiments were conducted in 1.2‐m wide × 1.2‐m tall × 5‐cm thick physical model tanks containing two soil layers differing in hydraulic conductivity by three orders of magnitude. The top 10 cm of the lower permeability layers contained 7400–7800 mg‐NAPL/kg‐soil; the NAPL was comprised of benzene, toluene, ethylbenzene, p‐xylene, o‐xylene, n‐propylbenzene, and 1,3,5‐trimethylbenzene (TMB) mixed in octane. Approximately 0.1 g‐Na2S2O8 was delivered per cm2‐interface area over 13–14 d. The S2O8
2− and SO4
2− concentration profiles suggest higher oxidant reaction rates when NaOH is delivered prior to, rather than after Na2S2O8. After 264 d and two treatments, hydrocarbon emissions from the NAPL source were reduced by 60% to 73% compared to a no‐treatment control tank. The incremental benefit of the second treatment was only about 10% of the effect of the first treatment.
Evaluating an Analytical Model to Predict Subsurface LNAPL Distributions and Transmissivity from Current and Historic Fluid Levels in Groundwater Wells: Comparing Results to Numerical Simulations
Authors: Lenhard Robert J. , Sookhak Lari Kaveh , Rayner John L. , Davis Greg B. 
Published: March 2018

AbstractA recent analytical model predicts free, entrapped, and residual LNAPL saturations and the LNAPL transmissivity in the subsurface from current and historic fluid levels in groundwater wells. As such, the model accounts for effects of fluid level fluctuations in a well. The model was developed to predict LNAPL specific volumes and transmissivities from current fluid level measurements in wells and either recorded historic fluid level fluctuations in wells or estimates. An assumption is made in the model that the predictions are not dependent on whether the historic highest or lowest fluid level elevations in a well occur first. To test the assumption, we conduct two simulations with a modified multiphase flow numerical code TMVOC that incorporates relative permeability‐saturation‐capillary head relations employed in the model. In one simulation, the initial condition is for fluid levels in a well at the historic highest elevations. In the other simulation, the initial condition is for fluid levels in a well at the historic lowest elevations. We change the boundary conditions so both historical conditions occur followed by generating the current condition. Results from the numerical simulations are compared to model predictions and show the assumption in the analytical model is reasonable. The analytical model can be used to develop/refine conceptual site models and for assessing potential LNAPL recovery endpoints, especially on sites with fluctuating fluid levels in wells.
Gamma/alpha‐zein hydrolysates as oral delivery vehicles: Enhanced physicochemical stability and in vitro bioaccessibility of curcumin
Authors: Pan Runting , Zou Yuan , Wang Jinmei , Wan Zhili , Guo Jian , Yang Juan , Yang Xiaoquan 
Published: March 2018

SummaryIn this study, we aimed to evaluate the potential of the γ‐zein hydrolysate (γ‐ZH) as a new delivery system for hydrophobic bioactive molecules such as curcumin (Cur). γ‐ZH‐Cur complexes (γ‐ZH‐Cur) with a particle size of 50–60 nm were successfully formed via the hydrogen bonding and hydrophobic interactions. Compared to α‐ZH, the complexation of Cur in γ‐ZH showed a better improvement in the water solubility and physicochemical stability of Cur and showed sustained release and greater potential for absorption of Cur. The differences in the loading capability, the physicochemical storage and the bioaccessibility of Cur between γ‐ZH and α‐ZH may be associated with the differences in the amino acid composition and typical sequence of peptides. These results indicate that γ‐ZH has a better ability to serve as a novel delivery for the hydrophobic bioactive molecules compared to α‐ZH.
The value of the Modified Early Warning Score for unplanned Intensive Care Unit admissions of patients treated in hospital general wards
Authors: Zografakis‐Sfakianakis Michail , De Bree Eelco , Linardakis Manolis , Messaritaki Argyri , Askitopoulou Helen , Papaioannou Alexandra , Aggouridakis Panagiotis 
Published: March 2018

AbstractAimTo determine the value of the Modified Early Warning Score (MEWS) for general ward patients and its potential use as an alarm tool for ward nurses.MethodsA combined prospective‐retrospective observational study was conducted with 153 patients in a university hospital (2013‐2014). All patients were admitted to the intensive care unit (ICU) from general wards. Parameters retrospectively studied were 5 MEWS values at 4 hourly intervals, up to 20 hours before ICU admission. Parameters prospectively studied were ICU length of stay, ICU mortality, and mortality after ICU discharge.ResultsMost frequent severe adverse events were acute respiratory failure (39.9%) and septic shock (20.3%). Modified Early Warning Score increased gradually during the last 20 hours, and most patients remained in the wards, above a cut‐off point ≥7 recorded at 4 hours before admission. Significant associations between latest MEWS score and ICU mortality and ICU length of stay were found. MEWS score≥ 7 hours before admission was highly associated with increased ICU and hospital mortality.ConclusionPatient deterioration in general wards can result in severe adverse events. Modified Early Warning Score is a strong predictor of outcome and may be used as a monitoring tool for potentially avoidable deaths and unplanned admissions to ICU.
Poloxamer 407‐chitosan grafted thermoresponsive hydrogels achieve synchronous and sustained release of antigen and adjuvant from single‐shot vaccines
Authors: Bobbala Sharan , Gibson Blake , Gamble Allan B , McDowell Arlene , Hook Sarah 
Published: March 2018

AbstractSustained‐release vaccine delivery systems may enhance the immunogenicity of subunit vaccines and reduce the need for multiple vaccinations. The aim of this study was to develop a thermoresponsive hydrogel using poloxamer 407‐chitosan (CP) grafted copolymer as a delivery system for single‐shot sustained‐release vaccines. The CP copolymer was synthesized using 1‐ethyl‐3‐(3‐dimethylaminopropyl)‐carbodiimide and N‐hydroxysuccinimide chemistry. The CP copolymer was a free flowing solution at ambient temperature and transformed rapidly into a gel at body temperature. The hydrogels were loaded with vaccine antigen and adjuvants or the vaccine components were encapsulated in poly (lactic‐co‐glycolic acid) nanoparticles in order to ensure synchronous release. The CP hydrogels were stable for up to 18 days in vitro. Release of both nanoparticles and the individual components was complete, with release of the individual components being modulated by incorporation into nanoparticles. In vivo, a single dose of CP hydrogel vaccine induced strong, long lasting, cellular and humoral responses that could protect against the development of tumors in a murine melanoma model.
Perceived benefits and barriers of implementing nursing residency programs in Jordan
Authors: AbuAlRub R.F. , Abu Alhaija'a M.G. 
Published: March 2018

AimsTo explore the challenges that face Jordanian nurses in the first year of employment; and understand the benefits and barriers of implementing a Nursing Residency Program from the perspectives of nurses and key informants.BackgroundMany researchers reported that novice nurses do not have an adequate level of competence needed in the real clinical practice to meet the increasing demands of healthcare systems.MethodsA descriptive qualitative approach using individual interviews and focus group discussions was utilized. The sample was a purposive one that consisted of 30 Jordanian nurses and six key informants. Data were recorded and then transcribed. Content analysis was used to analyze the data.FindingsThe results revealed several challenges that face nurses in their first year of experience such as reality shock, lack of self‐confidence, and burnout and intent to leave. Some of the perceived barriers of implementing the Program were issues concerned with the responsible regulatory body, payment, and monitoring and evaluation.ConclusionThe findings asserted that the implementation of the Nursing Residency Program for new practicing nurses would enhance their competencies and self‐ confidence; and decrease the rate of reality shock and turnover within the first year of employment.Implications for nursing and health policyPolicy makers, nurse educators, and nurse administrators and clinical nurses need to collaborate to develop a formal system with binding policies and regulations concerning the implementation of Nursing Residency Program. There is also a need to address and modify current orientation programmes offered by hospitals for novice nurses to enhance their transition into clinical practice.