ABSTRACT
In landfills, soil has traditionally been used as a material for both the daily and final covering of refuse. This chapter shows that intermediate and final landfill-covering soils are of great importance because of their particular interactions with the pollutant chemicals in leachate and gas. These interactions, and an understanding of them, are vital when considering landfills as either potential environmental pollutant sources or bioreactors which facilitate attenuation of key substances. The soil components provide surface area for interaction with microorganisms and pollutants. Although soil coverings constitute only a small fraction of the landfill volume, the total surface area per unit volume of the soil greatly exceeds that of refuse. Soil has a great buffering capacity for hydrophobic contaminants and charged molecules. Cosolvency, therefore, not only increases the soluble concentration but also increases biodegradation of hydrophobic molecules. The increased surface sorption of the metal ions to soil components may reduce the concentrations of the metals in solution to subcritical levels.
