Impact of Atmospheric Pressure Fluctuations on Nonequilibrium Transport of Volatile Organic Contaminants in the Vadose Zone: Experimental and Numerical Modeling

2021 ◽  
Author(s):  
Shengqi Qi ◽  
Yidong Wang ◽  
Liuwei Wang ◽  
Jian Luo ◽  
Deyi Hou
Keyword(s):  
Numerical Modeling ◽  
Vadose Zone ◽  
Organic Contaminants ◽  
Atmospheric Pressure ◽  
Pressure Fluctuations ◽  
Nonequilibrium Transport ◽  
Volatile Organic ◽  
Volatile Organic Contaminants ◽  
Atmospheric Pressure Fluctuations ◽  
Experimental And Numerical Modeling

scholarly journals Characterization and Remediation of Chlorinated Volatile Organic Contaminants in the Vadose Zone

2013 ◽  
Vol 12 (4) ◽  
pp. vzj2012.0137 ◽  
Author(s):  
Mark L. Brusseau ◽  
Kenneth C. Carroll ◽  
Michael J. Truex ◽  
David J. Becker
Keyword(s):  
Vadose Zone ◽  
Organic Contaminants ◽  
Volatile Organic ◽  
Volatile Organic Contaminants

Impact of Atmospheric Pressure Fluctuations on Vadose-zone Contaminant Plumes

2002 ◽  
Vol 757 ◽  
Author(s):  
Wayne C. Downs
Keyword(s):  
Carbon Tetrachloride ◽  
Vadose Zone ◽  
Atmospheric Pressure ◽  
Land Surface ◽  
Soil Column ◽  
Pressure Fluctuations ◽  
Pressure Sensors ◽  
Laboratory Work ◽  
Contaminant Plumes ◽  
Atmospheric Pressure Fluctuations

ABSTRACTField and laboratory studies have been underway at the INEEL and BYU to investigate the effect of atmospheric pressure fluctuations on the migration of contaminant plumes.In the field, two vadose-zone piezometer nests were instrumented to measure soil-pressures and carbon tetrachloride concentrations at depths of roughly 78-ft, 112-ft., and 150-ft., below ground surface in wells 25-ft. apart. At land surface, a manifold was constructed to systematically rotate from port to port at 15-minute increments of time. Contaminant concentrations were measured at each rotation, and soil pressures were measured at all ports at 15-minute increments. Atmospheric pressures were also recorded. Results showed that atmospheric pressure changes propagated downward lagged in time and dampened in amplitude. Carbon tetrachloride concentrations were observed to decrease with pressure increases at each port, suggesting that pressure increases pushed the plume downward. Increases in concentration were observed with decreases in pressure. Concentrations were observed to change at a port by as much as an order of magnitude. Modeling is underway to assist in isolating the transport mechanisms involved and assist in quantifying the effect of varied pneumatic permeability on pressure propagation.Laboratory work is underway at BYU to more carefully isolate the mechanisms of diffusive transport and pressure fluctuation in unsaturated conditions. A sealed soil column has been packed with sand and instrumented with a contaminant reservoir at one end and concentration sensor at the other. A mechanical syringe is used to vary the pressure within the tube, and pressure sensors have been emplaced.An affiliation has been established with researchers at the DOE Sandia laboratory to utilize a novel non-invasive vapor detector in our sealed-column laboratory work.

The Distribution of Volatile Organics in a Leachate Plume, Gloucester, Ontario

1987 ◽  
Vol 22 (1) ◽  
pp. 49-64 ◽  
Author(s):  
J.F. Devlin ◽  
W.A. Gorman
Keyword(s):  
Organic Contaminants ◽  
Source Area ◽  
Unconfined Aquifer ◽  
High Concentration ◽  
Organic Contamination ◽  
Aquifer System ◽  
Aquifer Systems ◽  
Volatile Organic ◽  
Volatile Organic Contaminants ◽  
Aquifer Sediments

Abstract The Gloucester Landfill is located near Ottawa, Ontario, on a northeast trending ridge of Quaternary age. The ridge comprises outwash sediments which make up two aquifer systems. A confined system exists next to bedrock, and is overlain by a silty-clayey stratum (the confining layer) which is, in turn, overlain by an unconfined aquifer system. Two independent volatile organic plumes have previously been identified at the landfill: the southeast plume, which has penetrated the confined aquifer system, and the northeast plume which is migrating in the unconfined aquifer. The distribution of volatile organic contaminants at the northeast plume site appears to be a function of two factors: (1) heterogeneities in the aquifer sediments are causing the channeling of contaminants through a narrow path; (2) the low fraction of organic carbon in the unconfined aquifer sediments at the northeast site is resulting in little retardation of the contaminants there, relative to those at the southeast site. Acetate was the only volatile fatty acid detected in the leachate. It was measurable only in areas where the volatile organic contamination was significant. Although methane was detected in the contaminated sediments, suggesting that microbial activity was present, the high concentration of acetate (>1000 ppm) which was detected down-gradient from the source area indicates that any biodegradation which is occurring is proceeding at a very slow rate.

The Stochastic Parametric Mechanism for Growth of Wind-Driven Surface Water Waves

2008 ◽  
Vol 38 (4) ◽  
pp. 862-879 ◽  
Author(s):  
Brian F. Farrell ◽  
Petros J. Ioannou
Keyword(s):  
Surface Water ◽  
Growth Rates ◽  
Atmospheric Pressure ◽  
Water Waves ◽  
Wave Amplitude ◽  
Pressure Fluctuations ◽  
Theoretical Understanding ◽  
Wave Growth ◽  
Atmospheric Pressure Fluctuations ◽  
Surface Water Waves

Abstract Theoretical understanding of the growth of wind-driven surface water waves has been based on two distinct mechanisms: growth due to random atmospheric pressure fluctuations unrelated to wave amplitude and growth due to wave coherent atmospheric pressure fluctuations proportional to wave amplitude. Wave-independent random pressure forcing produces wave growth linear in time, while coherent forcing proportional to wave amplitude produces exponential growth. While observed wave development can be parameterized to fit these functional forms and despite broad agreement on the underlying physical process of momentum transfer from the atmospheric boundary layer shear flow to the water waves by atmospheric pressure fluctuations, quantitative agreement between theory and field observations of wave growth has proved elusive. Notably, wave growth rates are observed to exceed laminar instability predictions under gusty conditions. In this work, a mechanism is described that produces the observed enhancement of growth rates in gusty conditions while reducing to laminar instability growth rates as gustiness vanishes. This stochastic parametric instability mechanism is an example of the universal process of destabilization of nearly all time-dependent flows.

scholarly journals 13C/12C Analysis of Ultra-Trace Amounts of Volatile Organic Contaminants in Groundwater by Vacuum Extraction

2010 ◽  
Vol 44 (3) ◽  
pp. 1023-1029 ◽  
Author(s):  
Helena I. F. Amaral ◽  
Michael Berg ◽  
Matthias S. Brennwald ◽  
Markus Hofer ◽  
Rolf Kipfer
Keyword(s):  
Organic Contaminants ◽  
Vacuum Extraction ◽  
Volatile Organic ◽  
Volatile Organic Contaminants ◽  
Ultra Trace
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