ABSTRACT
To better appreciate the various environmental and health threat problems arising from the pollutants residing on the land surface and in the subsurface of contaminated lands, we need to consider the nature of the land environment. Contamination of the ground can lead to severe consequences. Considering
pollutants
as those contaminants deemed to be threats to human health and the environment, it is important for us to be aware of the fate of the pollutants in the soil strata underlying the ground (land) surface. For simplicity in representation, the underlying soil strata will be generally identified as the
substrate
or
substrate material
. Figure 1.1 shows a schematic view of the potential pathways to biotic receptors for which pollutants in a contaminated land site might travel. The degree of threat (risk) posed by pollutants travelling along these pathways, and the processes affecting the fate of the pollutants on these pathways, will be some of the many key factors that will determine the course of action required to minimize or eliminate the threat. Threat minimization or elimination requires consideration for removal of the pollutants, containment of the pollutants, reduction of toxicity of the pollutants, and pollution mitigation — amongst the many action choices available. One of the key factors is
risk management
, i.e., the management of the pollutant threat such that the threat is reduced to acceptable risk limits as prescribed by regulations and accepted practice.
