Mathematical models for an undisturbed soil-column

Abstract

Some of the major industries of the Zebo region (China) include the petrochemical, pharmaceutical, china and ceramics sectors. Zibo is also abundant in natural resources. In support of the ceramics industry, they have large reserves of clay, limestone and bauxite. Consequently, there are a number of mines in the region and the outflow of acidic water from these metal and coal mines, known as acid mine drainage (AMD), is considerable. The AMD is rich in sulphate ions and contains other pollutants that are subsequently transferred to the soils and surrounding surface rivers through both irrigation and infiltration of the ground water.

To understand the behaviour of the soil in the presence of infiltrating pollutants and atmospheric precipitation, soil-column experiments were performed. A chosen soil sample was undisturbed in the sense that the structure of the soil layers and any pollutants within the column were preserved when the soil was transferred to the experimental apparatus. To simulate the processes that occur within the environment (infiltration and precipitation), polluted water (liquor) from a nearby source was introduced at the top of the column and once this material has infiltrated the column, clean water was allowed to flush through the apparatus. The initial concentration of various ions in the liquor were measured and throughout the experiment, the fluid that reaches the bottom of the column was collected and analysed.

The goal for the workshop is to derive a mathematical model that predicts the observed experimental time dependence of the ionic concentrations emerging from the bottom of the the apparatus. Developing the model will require an understanding of the physical and chemical mechanisms of the solute transport though the soil. This is an important first step in the eventual development of remediation schemes for the contaminated soil.