Testing of pesticide-leaching models is important in view of their increasing use in pesticide registration procedures in the European Union. This paper presents the methodology and major conclusions of a test of pesticide-leaching models. Twelve models simulating the vertical onedimensional movement of water, solute, heat, and, in particular, pesticides, through the soil pro®le were used by 36...

We present a methodology to characterize a continuum-scale model of transport in porousmedia on the basis of pore-scale distributions of velocities computed in three-dimensional pore-space images. The methodology is tested against pore-scale simulations of flow and transport for a bead pack and a sandstone sample. We employ a double-continuum approach to describe transport inmobile and immobile...

BACKGROUND In spite of many peritoneal tests proposed, there is still a need for a simple and reliable new approach for deriving detailed information about peritoneal membrane characteristics, especially those related to fluid transport. METHODS The sequential peritoneal equilibration test (sPET) that includes PET (glucose 2.27%, 4 h) followed by miniPET (glucose 3.86%, 1 h) was performed in ...

A generalized continuum framework for the theory of solute transport in fluids is proposed and systematically developed. This framework rests on the introduction of a generic force balance for the solute, a balance distinct from the macroscopic momentum balance associated with the mixture. Special forms of such a force balance have been proposed and used going back at least as far as Nernst’s 1...

Solute carriers are eukaryotic membrane proteins that control the uptake and efflux of solutes, including essential cellular compounds, environmental toxins, and therapeutic drugs. Solute carriers can share similar structural features despite weak sequence similarities. Identification of sequence relationships among solute carriers is needed to enhance our ability to model individual carriers a...

[1] The experimental evidence suggests that for many chemicals surface runoff and rapid preferential flow through the shallow unsaturated zone are significant pathways for transport to streams and groundwater. The signature of this is the episodic and pulsed leaching of these chemicals. The driver for this transport is the timing and magnitude of rainfall events which trigger rapid flow and the...

The mechanism by which active solute transport causes water transport in isotonic proportions across epithelial membranes has been investigated. The principle of the experiments was to measure the osmolarity of the transported fluid when the osmolarity of the bathing solution was varied over an eightfold range by varying the NaCl concentration or by adding impermeant non-electrolytes. An in vit...

The impact of permeability on solute transport process in a highly heterogeneous aquifer was analyzed using the Monte-Carlo method. The logarithm of the permeability (lnK) of aquifer was considered as a non-stationary field with increments being a truncated fractional Lévy motion (fLm) generated using the SRA3DC code. MODFLOW and MT3DMS code were used to solve the flow and solute equations, res...

Strongly sorbing chemicals (e.g., heavy metals, radionuclides, pharmaceuticals, and explosives) in porous media are associated predominantly with the solid phase, which is commonly assumed to be stationary. However, recent fieldand laboratory-scale observations have shown that in the presence of mobile colloidal particles (e.g., microbes, humic substances, clays, and metal oxides), colloids can...