Mapping the storing and filtering capacity of European soils

The purpose of the current study was to develop an estimation method based on available soil map information (categorical data) and thereafter estimate and map across Europe the soil filtering and storing capacity of different substances, which support ecosystem services and those which present a hazard to the ecosystem functioning. Pollutants were grouped as follows: (1) elements in cationic form; (2) elements in anionic form; (3) solids and pathogenic microorganisms; (4) non-polar organic chemicals and (5) nonaqueous phase liquids (NAPLs). The spatial pattern of areas with high soil storing capacity are largely different depending on the stored substances. In general, those soils are characterized by good storing capability that have thick topsoil and subsoil layers and these layers are free from the effects of groundwater. As the content of clay and humus content increases and the stone or gravel content decreases, the storage capacity increases simultaneously. However, the effect of soil pH and the soil mineralogy is different depending on the various groups of pollutants (e.g. the calcareous soils with high swelling clay mineral content are able to bind more cations, whereas the acidic soils or the soils with high sesquioxide content have higher anion storing capacity). The soil filtering capacity pattern of Europe in the case of different groups of substances are in part similar to the storing capacity pattern. The main difference between the two parameters was to take account of infiltration rate and the thickness of the filtration path up to the groundwater during the filtering capacity estimation.