Within the overall transport process, attenuation processes may cause movement of the chemical to differ from that of the bulk flowing groundwater, for example dispersion, sorption and chemical or biological degradation of the chemical. Such attenuation processes potentially act to mitigate the impact of chemicals and are a function of both the specific chemical and geologic domain. Indeed, attenuation may vary significantly between individual chemicals and within different geological settings. In recent years “natural attenuation” (NA) of organic contaminants has been increasingly recognised to play an important role in many aquifer systems leading to “monitored natural attenuation” (MNA) becoming a.
