The dominant role of structure for solute transport in soil: Experimental evidence and modelling of structure and transport in a field experiment H.-J. Vogel, I. Cousin, O. Ippisch, and P. Bastian Institute of Environmental Physics, University of Heidelberg, Germany INRA, Unité de Science du Sol, Orléans, France Interdisciplinary Center of Scientific Computing, University of Heidelberg, Germany...

Numerous models have been developed for predicting major ion chemistry in the soil zone and in recharge to groundwater. Soils that contain CaCO, are prevalent in arid and semiarid regions, as well as in humid and temperate regions that have been glaciated or contain carbonate bedrock. Under these conditions, carbonate-solution reactions and ion exchange are the dominant chemical processes. In t...

Transport in porous media is quite complex, and still yields occasional surprises. In geological porous media, the rate at which chemical reactions (e.g., weathering and dissolution) occur is found to diminish by orders of magnitude with increasing time or distance. The temporal rates of laboratory experiments and field observations differ, and extrapolating from laboratory experiments (in mont...

Field-scale solute transport is typically difficult to model due to the complexity and heterogeneity of flow and transport in natural soils. The stream tube model attempts to stochastically describe transport across the field for relatively short travel distances by viewing the field as a series of independent vertical soil columns. This study investigates the stream tube model with the chemica...

Larsson, M. 1999. Quantifying macropore flow effects on nitrate and pesticide leaching in a structured clay soil. Field experiments and modelling with the MACRO and SOILN models. Doctoral thesis. ISSN 1401-6249, ISBN 91-576-5489-1 Rapid non-equilibrium flow of water in soil macropores is one significant, yet poorly understood, process controlling solute transport in soils. To protect surface wa...

In recent years, researchers have focused on modeling of multicomponent reactive transport and have developed models to study the mobility of potentially toxic heavy metals in the subsurface. In this study, a mathematical model for understanding the fate of a typical heavy metal (lead) in unsaturated soil is developed. The entire modeling activity comprises of three parts. During the first part...

The current concept of fluid transport in vertebrates is that water moves passively down the osmotic gradient created by an active transport of solute. Earlier suggestions that these tissues could transport water in the absence of a concomitant movement of solute have been rejected (Curran, 1965; Diamond, 1965; Robinson, 1965, 1966). Interest is now focused on the mechanism by which water movem...