Transport of reactive contaminants in heterogeneous porous media

Abstract

The potential for human activities to adversely affect the environment has become of increasing concern during the past two decades. Concomitantly, the transport and fate of contaminants in subsurface systems has become one of the major research areas in the environmental, hydrological, and Earth sciences. An understanding of how contaminants move in the subsurface is needed to evaluate the probability of contaminants associated with a chemical spill reaching an aquifer and contaminating groundwater. This knowledge is also required to develop and evaluate methods for cleaning up contaminated soils and aquifers. Just as importantly, knowledge of contaminant transport and fate is necessary to design “pollution prevention” strategies. A tremendous body of literature on contaminant transport has been generated in response to these needs. This literature consists primarily of results obtained by theoretical, experimental, and mathematical modeling based investigations and, to a much lesser extent, field experiments. This paper consists of a brief review of some of the major aspects associated with the transport of reactive contaminants in heterogeneous subsurface environments. It begins with a review of basic concepts related to contaminant transport, followed by a discussion of the results obtained from some of the few well‐controlled field experiments designed to investigate transport of reactive contaminants in the subsurface. Some of the major factors controlling contaminant transport will then be discussed, followed by a review of conceptual and mathematical approaches used to represent those factors in mathematical models. A brief overview of future needs and opportunities in contaminant transport will close the discussion.

Generalized hydrogeologic framework and groundwater budget for a groundwater availability study for the glacial aquifer system of the United States

“…Glacial deposits are quintessentially heterogeneous, and site-specific layers or lenses ranging from less than a foot to several feet thick and extending from tens to hundreds of feet may have profound consequences on local groundwater availability, especially in determining water-quality conditions that may either limit or provide potable water (Brusseau, 1994). Groundwater availability on a regional scale is less influenced by local heterogeneity because the general spatial patterns and temporal trends can be identified at the regional scale.…”

Non-invasive flow path characterization in a mining-impacted wetland

“…Preferential flow paths result in earlier breakthrough time, lower residence time, and more pronounced tailing (Brusseau, 1994). The existence of mining waste piles in the wetland increases the likelihood that preferential flow exists in the wetland because deposition of mining waste often results in vertical grading, with larger grains tumbling down and finer grains settling over the surface (Smith, 1995).…”

“…Heterogeneity and preferential flow path development in AMD settings has been shown to decrease the e ciency of contaminant attenuation (Malmström et al, 2008), likely because preferential flow paths reduce the residence time of solutes in the subsurface and contact with attenuating agents (Brusseau, 1994). Deposition of mining waste piles typically results in graded bedding, through which most discharge is concentrated into a small of the total rock volume (Morin & Hutt, 1994;Smith, 1995).…”

Effective retardation factor for transport of reactive solutes in highly heterogeneous porous formations

“…The complexity of reactive plume transport can be attributed to several factors including nonlinearity in sorption isotherms, rate-limited sorption/desorption, and sorption spatial heterogeneity, as summarized by Brusseau [1994]. This note investigates the impact of sorption heterogeneity (spatial variability of sorption distribution coefficient K d or retardation factor R) on the average delay of reactive plumes by assuming equilibrium linear sorption.…”