ABSTRACT
Two main transfer pathways are important for the assessment of trace-element (TE) risk in relation to living organisms:
• The soil-plant (fodder and food crop) pathway, which introduces TEs into the food chain and/or phytotoxicity
• Direct (ingest, inhale) uptake by humans and animals In addition to these ecotoxicological approaches, it is indispensable to consider geogenic and diffuse-anthropogenic background TE concentrations in soil. Knowledge of the background concentration is necessary to evaluate increased inputs of TEs into soils due to airborne emissions, flooding, or sewage sludge disposal. Limits or reference values of critical levels of soil loads have been expressed until now in terms of total TE contents.1 –4
In the Czech Republic and at geological institutes in Germany, TE background values of the main soil-lithological units have been expressed as the total content in acid extracts (HNO3 HClO4 HF). The soil-lithological groups were classified according to their mineralogical and textural properties. The upper boundaries of the variability of TE values are regarded as soil contamination limits. Extreme geogenic loads are assessed separately.
