Soil bacterial processes and dynamics

Abstract

Under the influence of regional groundwater ow, pollution in an aquifer can migrate to streams or wells. This can have catastrophic consequences for human health and local ecosystems. Fortunately, there is a suite of microorganisms that exist in the subsurface that can convert contaminants into less toxic chemicals. In this thesis, we seek to model the interaction between these microbial populations and the contaminant. A reaction-transport model is created to describe the migration of chemical species in a subsurface environment. With this model, we derive an expression for the location of a reaction front in the plume and the speed at which it moves. Oscillatory chemical concentration pro les are frequently observed in borehole readings but they are often dismissed as noisy data without closer examination. We propose that such oscillations are a result of microbial populations competing for nutrient sources. A description of this interaction is provided which is found to exhibit temporal and spatial oscillatory behaviour. A recent thesis by Razak (2009) is reviewed in which the phenol degradation rate by a particular strain of bacteria was experimentally measured. Building a modi ed version of the Van Impe et al. (2005) model, a description is derived of the biomass growth, oxygen depletion and phenol consumption in a continuous ow environment.