High concentrations of 2,4-dinitrotoluene (2,4-DNT) and 2,6-dinitrotoluene (2,6-DNT) are present in vadose zone soils at many facilities where explosives manufacturing has taken place. Both DNT isomers can be biodegraded under aerobic conditions, but rates of intrinsic biodegradation observed in vadose zone soils are not appreciable. Studies presented herein demonstrate that nutrient limitation...

Currently there is no in situ method to detect and quantify complete mineralization of chlorinated hydrocarbons (CHCs) to CO2. Combined isotopic measurements in conjunction with traditional chemical techniques were used to assess in situ biodegradation of trichloroethylene (TCE) and carbon tetrachloride (CT). Vadose zone CHC, ethene, ethane, methane, O2, and CO2 concentrations were analyzed usi...

According to the characteristics of groundwater in arid area, this paper proposes DRAV model for groundwater vulnerability assessment, where D is groundwater depth, R is the net recharge of aquifer, A is the aquifer characteristics, and V is the lithology of vadose zone. As a case study, the paper assesses the vulnerability of pore phreatic water in Tarim Basin of Xinjiang, China by using the D...

Solid low-level radioactive wastes at the Savannah River Site (SRS) are disposed in trenches. In order to determine the permissible radioactive inventory limits for such disposal facilities, it is required to assess the behavior of radioactive waste material over long periods of time. The sensitivity of flow and I-129 (and similar radionuclides) transport in groundwater in the vadose zone to th...

[1] Most studies in vadose zone hydrology use a single conceptual model for predictive inference and analysis. Focusing on the outcome of a single model is prone to statistical bias and underestimation of uncertainty. In this study, we combine multiobjective optimization and Bayesian model averaging (BMA) to generate forecast ensembles of soil hydraulic models. To illustrate our method, we use ...

soils. A natural obstacle to this practice is the accelerated aging of iron and loss of reactivity resulting from O2 Permeable zerovalent iron (Fe0 ) barriers have become an estabin the soil atmosphere. Despite this apparent limitation, lished technology for remediating contaminated ground water. This same technology may be applicable for treating pesticides amenable situations could arise wher...

We present a simple analytical solution for one-dimensional steady heat transfer with convection and conduction through a multilayer system such as a vadose zone. We assume that each layer is homogeneous and has a constant thermal diffusivity. The mass/heat flow direction is perpendicular to the layers, and the mass flow rate is a constant. The analytical solution presented in this study also a...

Many studies of water flow and solute transport in the vadose zone require estimates of the unsaturated soil hydraulic properties, including the soil water retention curve ~WRC! describing the relationship between soil suction and water content. An artificial neural network ~ANN! approach was developed to describe the WRC using observed data from several soils. The ANN approach was found to pro...