Behaviour of cyanides in soil and groundwater: A review

Most people associate the word cyanide with an extremely dangerous and fast -acting poison. However, there are several cyanide species, of varying toxi city, depending on the source to cyanide contamination. The most important cyanide compounds, as well as the most important sources of cyanide contami nation in soils and groundwater are discussed. Toxicological and analytical aspects of cyanide containing compounds are briefly touched. The behaviour of cyanide compounds in soil and groundwater is governed by many interacti ng chemical and microbial processes. Redox conditions and pH are of importa nce for the leaching and degradation of iron cyanide complexes. Free cyanid e is degraded under both aerobic and anaerobic conditions, while documentat ion of the degradability of iron cyanide complexes only exists under aerobi c conditions. The risk associated to the cyanide contained in the different types of sources is evaluated. At gas work sites, where cyanide is mainly present as iron cyanide complexes, the risk for effects on humans from expo sure to cyanide compounds seems to be of minor relevance.