Turfgrass managers have suspected that runoff-independent movement of herbicides and fertilizers is partially responsible for uneven turfgrass quality in sloped areas. We hypothesized subsurface lateral solute transport might explain this phenomenon especially areas with abrupt textural changes between surface horizons. A study was conducted to track using bromide (Br−), a conservative tracer, ...

a solute diffuses may cause the observed, or effective diffusion coefficient (De) to be lower than the diffusion Diffusion is often the dominant mode of solute transport in soils coefficient of a compound in water (D0) (Rao et al., when advection is minimal. This paper describes the application of a radial diffusion cell method to estimate the effective diffusion coeffi1980). Moreover, exclusio...

We collected and analyzed breakthrough curve (BTC) data to identify the parameters controlling transport from a series of undisturbed fully saturated soil cores and a field test at the Shale Hills Critical Zone Observatory in central Pennsylvania. The soil cores were collected in a continuous hole extending across the soil profile vertically at one location to quantify how solute transport beha...

242 A dispersion are considered to be the dominant mechanisms of solute transport in the vadose zone, i.e., the variably saturated layer of soils and sediments between the soil surface and groundwater table (Jury and Flühler, 1992). Advection is associated with the average water fl ux or velocity, whereas hydrodynamic dispersion is modeled using an analog of Fick’s law corresponding to the Brow...

We study solute transport in porous media with periodic microstructures consisting of interconnected thin channels. We discuss a local physical mechanism that occurs at the intersections of channels and promotes mixing of the solute with the solvent (i.e., the host liquid). We identify the parameter regime, where this mechanism is the dominant cause of dispersion, and obtain the effective or ma...

Water having entered a stream channel from the surrounding catchment may continue to have connections with the catchment. In the stream’s hyporheic zone, water “in the channel” exchanges with “groundwater” in the bed of the stream. Hyporheic exchange flows typically occur at scales small relative to the length and volumetric transport characteristics of the stream. Nevertheless, it is well docu...

Solute transport through interpenetrating polymeric networks of poly(vinyl alcohol) and poly(acrylic acid) at pH 3 or 6 was studied in order to investigate the influence of possible solute binding on the transport process through the networks. Diffusion of theophylline, vitamin B12, and myoglobin was analyzed, and diffusion and partition coefficients were determined. Analysis using the free vol...

Local-scale heterogeneity in natural aquifers plays a key role in solute mixing and chemical reactions. The incorporation of this scale of heterogeneity in traditional grid-based methods is difficult because of large computational costs and because of their poor accuracy in the advective-dominated transport found in most practical problems. Particle methods are an attractive alternative to simu...

Laboratory experiments were conducted to study solute transport along preferential flow paths in unsaturated, inclined fractures. Qualitative aspects of solute transport were identified in a miscible dye tracer experiment conducted in a transparent replica of a natural granite fracture. Additional experiments were conducted to measure the breakthrough curves of a conservative tracer introduced ...

For the last 40 years, our understanding of the mechanistic basis for solute transport across membranes has been shaped by the alternating access mechanism (22, 37, 56). In this model, transported solutes bind to a site in the transporter that can be exposed by conformational changes to one side of the membrane or the other. Early mechanistic interpretations of this model suggested that the tra...