Mapping the soil metal No Effect Concentration for terrestrial organisms in European countries and comparison to national soil policies thresholds

Vandeuren, Aubry [UCL] Pereira, Benoît [UCL] Sonnet, Philippe [UCL] Oorts, Koen [ARCHE CONSULTING, Ghent, Belgium]

High levels of metal concentrations in soils constitute a threat to terrestrial organisms leading possibly to a loss of biodiversity and/or soil functions. This is why most European countries have adopted soil protection policies each containing soil threshold values representing a limit above which remediation interventions will be possibly required. The toxicity of metals in soils has been assessed with the Predicted No Effect Concentration (PNEC) calculator methodology. This approach relies on chronic toxicity data for terrestrial organisms and Ageing/Leaching factors which take into account soil parameters such as organic matter content, clay content, pH and cation exchange capacity. The aim of this study is to map the PNEC in European countries in order to compare their soil threshold values with the observed PNEC values. The soil parameter dataset used for computing the PNEC is the Lucas Topsoil Dataset, which includes 20 000 soils parameter analyses similarly spatially sampled across Europe. Here we present maps and comparison results for Cu and Zn. The resulting maps show that the PNEC exhibits strong variations across Europe. This map allows to compare the level of the soil threshold values for each country with the observed distribution of PNEC. This approach highlights differences in soil environmental conservation level among the compared countries. Although it takes into account only the soil ecosystem receptors, this work provides a first approach toward consistent soil threshold values across Europe.