The behaviour of Antarctic soils towards contaminant materials depends on the nature of the contaminant and the properties of the soil. Relevant properties are: depth to permafrost, whether the permafrost is ice-cemented or dry frozen; the active layer depth, active layer moisture content, and frequency of liquid water; soil salinity characteristics; and the geological composition of the soil materials.
Soil contaminations in the McMurdo region have been investigated through several years in a number of studies, including site surveys, field investigations, and experiments. Results of these studies are summarized in this paper and the significance of the contaminations is discussed. The behaviour of contaminants at the sites investigated conforms to existing knowledge of the soil properties. In the presence of some summer water or occasional moisture influxes from snowmelt, soluble contaminants may be transported variable distances through soils, both downwards and laterally, depending on the amount of water available. Ice-cemented permafrost restricts the downward movement of most contaminants but may aid distribution via lateral flow, especially low-freezing-point contaminants such as hydrocarbons. In dry-frozen soils, low-freezing-point contaminants may penetrate deeply into the soil.
With respect to the sites investigated, the heavy metal contaminations were typically above the values from undisturbed sites, but there may at times be appreciable natural variation. The presence of solid materials in soils — such as particles of plastics, wood, fibre, etc — represents a widespread and pernicious form of contamination, because they are foreign to the environment and are non-degradable.