title: Multiple-tracer tests for contaminant transport process identification in saturated municipal solid waste.
abstract: Two column tests were performed in conditions emulating vertical flow beneath the leachate table in a biologically active landfill to determine dominant transport mechanisms occurring in landfills. An improved understanding of contaminant transport process in wastes is required for developing better predictions about potential length of the long term aftercare of landfills, currently measured in timescales of centuries. Three tracers (lithium, bromide and deuterium) were used. Lithium did not behave conservatively. Given that lithium has been used extensively for tracing in landfill wastes, the tracer itself and the findings of previous tests which assume that it has behaved conservatively may need revisiting. The smaller column test could not be fitted with continuum models, probably because the volume of waste was below a representative elemental volume. Modelling compared advection-dispersion (AD), dual porosity (DP) and hybrid AD-DP models. Of these models, the DP model was found to be the most suitable. Although there is good evidence to suggest that diffusion is an important transport mechanism, the breakthrough curves of the different tracers did not differ from each other as would be predicted based on the free-water diffusion coefficients. This suggested that solute diffusion in wastes requires further study.
authors.affiliation: School of Civil Engineering and the Environment, University of Southampton, Highfield, Southampton SO17 1BJ, UK. Electronic address: n.d.woodman@soton.ac.uk.
authors.forename: N D
authors.initials: ND
authors.lastname: Woodman
authors.affiliation: School of Civil Engineering and the Environment, University of Southampton, Highfield, Southampton SO17 1BJ, UK.
authors.forename: T C
authors.initials: TC
authors.lastname: Rees-White
authors.affiliation: School of Civil Engineering and the Environment, University of Southampton, Highfield, Southampton SO17 1BJ, UK.
authors.forename: A M
authors.initials: AM
authors.lastname: Stringfellow
authors.affiliation: School of Civil Engineering and the Environment, University of Southampton, Highfield, Southampton SO17 1BJ, UK.
authors.forename: R P
authors.initials: RP
authors.lastname: Beaven
authors.affiliation: School of Civil Engineering and the Environment, University of Southampton, Highfield, Southampton SO17 1BJ, UK.
authors.forename: A P
authors.initials: AP
authors.lastname: Hudson
mesh_terms: D004058:Diffusion; D004784:Environmental Monitoring / Q000379:methods*; D060587:Groundwater / Q000032:analysis; D016062:Porosity; D012037:Refuse Disposal; D012989:Soil Pollutants / Q000032:analysis*; D062611:Solid Waste / Q000032:analysis*; D064091:Waste Disposal Facilities
chemical_list: D012989:Soil Pollutants; D062611:Solid Waste
keywords: Breakthrough curve; Compressive stress; Conservative; MBT; MSW; Tracer