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In 1999, ~72 [m.sup.3] of denatured fuel-grade ethanol spilled at a bulk fuel terminal that had existing contamination within the subsurface. An unanticipated increase in the measured depth of the light nonaqueous phase liquid (LNAPL) was observed in nearby monitoring wells following the spill. This paper presents results of a laboratory analysis designed to understand the apparent increase in LNAPL mobility at this site. The two-dimensional stainless steel and glass tank allowed visual assessment of the potential effects that the addition of denatured ethanol may have on a site with pre-existing gasoline contamination. Digital images of gasoline and ethanol spill experiments were analyzed for changes in the characteristics of the existing gasoline pool and residual gasoline saturation in the unsaturated zone. Reductions in the surface and interfacial tensions resulted in significant changes in the size, shape, and saturation of the gasoline pool after the addition of ethanol to the system. The final gasoline pool occupied a smaller area and had a higher saturation. In addition, some smearing of the gasoline into the saturated zone occurred as the capillary fringe was depressed., Introduction Over the last five years, a significant debate has developed surrounding the use of oxygen-bearing chemicals as additives for automotive fuels (Franklin et al. 2000; Nadim et al. 2001). [...]

Mathematical models for soil water retention characteristic [h([theta])] and unsaturated conductivity function [K([theta])] from particle-size distribution (PSD) and bulk density data are indirect and empirical approaches to estimate these hydraulic functions. Often rimes, mathematical models are fit to sparse PSD data sets to provide the input for h([theta]) and K([theta]) functions. The objective of this study was to determine whether the choice of a particular mathematical model to represent the continuous PSD significantly affects the predicted soil hydraulic properties. We considered four PSD models with between one and four fitting parameters. For most of the soils, the one-parameter Jaky model for generating PSD input, resulted in the best estimate of soil hydraulic properties. This finding indicates that the linear relationship between the PSD and the void-size distribution (VSD) (or between particle volume and pore volume) defined by the AP model would be not appropriate for most soils. This result suggests that the nonlinear relationship between the PSD and the VSD of the Jaky model would more appropriate. The PSD generated by other models provided better input to the h([theta]) and K([theta]) functions for clay soils.

An accurate mathematical representation of particle-size distributions (PSDs) is required to estimate soil hydraulic properties or to compare texture measurements from different classification systems. The objective of this study was to evaluate the ability of seven models (i.e., five lognormal models, the Gompertz model, and the Fredlund model) to fit PSD data sets from a wide range of soil textures. Special attention was given to the effect of texture on model performance. Several criteria were used to determine the optimum model with the least number of fitting parameters when other conditions are equal. The Fredlund model with four parameters showed the best performance with the majority of soils studied, even when three criteria that impose a penalty for additional fitting parameters were used. Especially, the relative performance of the Fredlund model in regard to other models increased with increase of clay content. Among all soil classes, the lognormal models with two or three parameters showed better fits for silty clay, silty clay loam, and silt loam soils, and worse fit for sandy clay loam soil.

The efficacy of using remediation to lower subsurface contamination by dense nonaqueous phase liquids (DNAPLs) is dependent on its distribution in the porous medium. This study used a model incorporating electrostatic and van der Waals forces to predict the wetting behavior of multiple systems containing a quartz surface, water and a DNAPL.

Environmental impact analysis indicates that although methyl tert-butyl ether and ethane share some similarities, ethanol's high degree of biodegradability under both anaerobic and aerobic conditions will cause possible groundwater contamination to be more manageable and less severe. However, ethanol's hygroscopic nature and it's depletion of groundwater electron acceptors and nutrients are cited as possible limitations for its complete implementation as a gasoline oxygenate or as a biomass fuel. In addition, accompanying graphs include information regarding ethanol half-life and ethanol partitioning.

The objective of this work is to provide a preliminary screening of the effectiveness of alternative sorbents for treating ground water contaminated with methyl tert-butyl ether (MTBE). Sorbents studied include synthetic carbonaceous resins, porous graphitic carbon, C18 silicas, and acrylic resins. Activated carbon was also tested for comparison purposes. Bottle point isotherms show that porous graphitic carbon and two synthetic carbonaceous resins have a greater capacity for MTBE than activated carbon. However, the required addition of a wetting agent to suspend and activate the porous graphitic carbon makes this sorbent unsuitable for drinking water purposes. The synthetic carbonaceous resins tested were found to have capacities three to five times greater than activated carbon at an MTBE concentration of 1 mg/L. The application of the Dubinin-Astakov isotherm to data for the synthetic carbonaceous resins suggests that the mechanism of adsorption is micropore filling. Additional bisolute experiments with m-xylene as a representative gasoline contaminant indicate that the m-xylene is preferentially sorbed, depleting the micropore volume available for MTBE sorption. The extent of this competitive adsorption was directly predicted from measured concentrations of the monoaromatic hydrocarbon.

The potential for changes in the wettability of a subsurface system following exposure of sands to a variety of non-aqueous-phase liquids (NAPLs) was assessed. Many of the NAPLs were collected from field sites with on-going NAPL recovery systems. Three methods were used to evaluate the wetting conditions: contact angle measurements, a qualitative bottle test, and capillary pressure-saturation curves. The results clearly show that a wide range of wetting conditions can be expected following spills of complex NAPL mixtures to the subsurface. NAPLs comprised of higher molecular weight constituents - such as creosote - or with added surfactants - such as gasoline - had a greater impact on the system wettability than the lower molecular weight NAPLs. Neat solvents did not have a significant impact on the wettability of quartz surfaces. Many of the petroleum products tested resulted in the formation of weakly water-wet surfaces. Under these conditions, the potential recovery of NAPL from the subsurface would be maximized. Much lower recoveries would be expected for the NAPL-wetting creosote and coal tar contaminants, however.

Many interventions designed to curb energy use are ineffective because they fail to inspire individuals to engage in proenvironmental behavior and interact meaningfully with energy information. This field experiment targeted individuals' personal motivations and goals in combination with sensor-recorded energy feedback to decrease electricity and water consumption. Residents from 77 "smart" apartments were randomly assigned to attend a multifaceted motivational program and set action-oriented energy goals. Participants were also randomly assigned to receive interactive energy feedback. Continuous electricity and water data were then collected for 3 months. Those who received the motivational intervention used significantly less hot water than those who did not receive the intervention. Moreover, those exposed to action-focused feedback used significantly less electricity than those who did not receive the feedback—an effect that was more pronounced in the motivation condition. Results support the use of interventions directed at personal proenvironmental motivations and action-focused group goals. [ABSTRACT FROM AUTHOR]