A model of the effects of nonuniform soil-water distribution on the subsurface migration of bacteria: Implications for land disposal of sewage

Australia produces one of the highest volumes of agricultural, industrial, and municipal wastes per capita in the world. Increasingly, the public is demanding statutory authorities investigate environmentally sound methods of land application. However, a real danger associated with land disposal of wastes, in particular sewage, is the possible contamination of groundwater and threats to public health resulting from transport of pathogenic micro-organisms through the vadose zone. The study of the transport and fate of micro-organisms in soils is also of vital importance in the fields of oil recovery, biological control of plant root diseases, and in-situ bioremediation of contaminated soils and aquifers from industrial accidents. The objectives of this paper are 1. explore the extent of spatial and temporal heterogeneity found in the soil-water patterns in Australian soils, and establish the framework for a mathematical model of the population dynamics and mobility of soil bacterial transport through the unsaturated zone of soils. odel explicitly incorporates spatial and temporal heterogeneity in describing these dynamics.