Deriving ecological risk-based soil quality values in the Basque Country.

Most industrialised countries are currently drawing up their procedures to deal with contaminated land. In the Basque Country generic soil quality values applicable to different land uses have been drawn up for many common soil inorganic and organic pollutants, to assist in the site assessment process. In this paper we present those values aimed at protecting ecosystems as the main target at risk. Ecological risk was defined on the basis of effects on the structure of the soil invertebrate community. Ecotoxicological data from laboratory tests were used in combination with a theoretical extrapolation method. The following groups of compounds were assayed: heavy metals, cyanides, aromatic compounds, polycyclic aromatic hydrocarbons, HCH isomers, chlorinated organic compounds, and mineral oil. A specific toxicity database was created. The reliability of the values obtained as well as the limitations of the derivation process are discussed.