introduction: preferential flow is one of the major processes influencing the rapid movement of pollutants to ground water.  macropores created by plant roots provide pathways for rapid transport of pollutants in a soil profile. the growth of plant roots into soil causes creation of big pores that improve water movement and solute transport through soil profile. field soils or undisturbed soils...

This study compares saturated hydraulic conductivities (Ks) of three sandy soils such as coarse, medium and fine sand. The Ks was obtained using three different methods: empirical methods based on the grain size analysis, the relative effective porosity model (REPM), and breakthrough curve analyses based on tracer tests. Column drainage tests were performed to characterize the water retention p...

1. Abstract Motivated by field measurements of aquifer hydraulic conductivity (K), recent tech5 niques were developed to construct anisotropic fractal random fields, in which the scaling, 6 or self-similarity parameter, varies with direction and is defined by a matrix. Ensemble 7 numerical results are analyzed for solute transport through these 2-D “operator-scaling” 8 fractional Brownian motio...

The present study proposes a model to explain the adsorption process through ionexchange membrane adsorbers. The model is defined by the continuity equation, expressed as a differential mass balance of the solute over a section of the membrane, and the Langmuir isotherm. The proposed model uses dimensionless variables that were defined by characteristic times of the global process. To examine t...

soil water retention curve is one of the crucial input parameters in any modeling study on water flow and solute transport in soils. direct measurement of soil water retention curve is time-consuming and costly. alternatively, pedotransfer functions (ptfs) may be used to indirectly estimate the soil water retention curve from easily measured soil properties. many equations for the soil water re...

A parameter estimation procedure, sequential uncertainty domain parameter fitting (SUFI), is presented and has the following characteristics. The procedure is sequential in nature, meaning that one more iteration can always be made before choosing the final estimates. The procedure has a Bayesian framework, indicating that the method operates within uncertainty domains (prior, posterior) associ...

We show that phase separation can occur in a one-component liquid outside its coexistence curve (CX) with addition of a small amount of a solute. The solute concentration at the transition decreases with increasing the difference of the solvation chemical potential between liquid and gas. As a typical bubble-forming solute, we consider O2 in ambient liquid water, which exhibits mild hydrophobic...

The transient storage model ~TSM! is the most commonly used model for stream–subsurface exchange of solutes. The TSM provides a convenient, simplified representation of hyporheic exchange, but its lack of a true physical basis causes its parameters to be difficult to predict. However, the simple formulation makes the model a useful practical tool for many applications. This work compares the TS...

This study investigated the removal of trace organic contaminants by a combined membrane bioreactor - granular activated carbon (MBR-GAC) system over a period of 196 days. Of the 22 compounds investigated here, all six hydrophilic compounds with electron-withdrawing functional groups (i.e., metronidazole, carbamazepine, ketoprofen, naproxen, fenoprop and diclofenac) exhibited very low removal e...