A column study of soil contamination by lead: influence of pH and carbonate content. II. Mathematical model

A mathematical model is used for the interpretation of the results from earlier experimental studies in lab-scale columns on the contamination of a carbonatic soil with lead. Local equilibrium conditions suffice to reproduce the experimental curves for every pH value of the influent contaminant solution and carbonate content of the soils essayed, but heterogeneous contact between the aqueous and solid phase should be included. This heterogeneous contact is responsible for the important tailing effects observed, and is difficult to estimate even for the lab conditions. Then, important uncertainties should be accepted both for risk assessment and in situ remediation feasibility studies.