Transport of Escherichia coli Through Intact and Disturbed Soil Columns

Abstract

The transport of antibiotic resistant Escherichia coli through several soils was evaluated. Up to 96% of the bacteria irrigated onto the surface of 280 mm deep intact columns were recovered in the effluent. Soil structure appeared to be related to the extent of transport. Columns prepared from mixed, repacked soil were much more effective bacterial filters than the intact soils. As rate of water input increased, the fraction of E. coli recovered in the effluent increased. The observed behavior of E. coli and the Cl⁻ solution in which they were suspended suggests that flow through soil macropores, which bypasses the adsorptive or retentive capacities of the soil matrix, is a common phenomenon. In waste disposal systems dependent on purification in the soil profile, this could significantly increase the probability of groundwater contamination.