Decisions on the remediation of metal contaminated soils are based on risk estimates derived from soil guideline values. Soil guideline values for metals are most commonly based on toxicological reference values. However guideline values are not only a reflection of scientific understanding but also reflect political decisions and legislative requirements, implemented by the regulator.
The United Kingdom is one such example of how changes to legislation of influenced the need to understand background soil concentrations. Part 2A of the contaminated land stator Guidance was issued by Department of Environment, Food and Rural Affairs in April 2012 (Defra, 2011). This guidance outlined changes to how contaminated land would be considered in the United Kingdom. Under this new guideline the term “normal” was introduced to the regulatory system with the requirements to remediate soils to normal levels.
Normal background concentration of soil contaminants not only includes geological and natural variation in soil element concentration but that of historical contamination and “normal” concentration of different elements found in soils of different environments (urban vs. rural). This series of post will be considering the important of determining soil background concentration and the different approaches which can be used to derive background concentration of soil contaminates in the environment.
Defra, 2011. Draft Contaminated Land Statutory Guidance