ABSTRACT
This study identifies the areas where groundwater is likely to display high natural background levels in trace elements in the Water Authority Rhône-Méditerranée & Corse Basin. The natural occurrence of trace elements in the local geological formations drained by groundwater and surface water is identified from published literature, existing trace element analysis in soils and the identification of a mining index. These data, coupled with the geochemical status of the natural water (pH, redox-conditions, temperature, concentration in dissolved oxygen …), allow the potential mobilisation of trace elements to be predicted. These and other data have been assembled within a GIS format to prepare an overall risk map for high natural background levels. For each defined area, depending on the relevance of the information available to identify this risk, a degree of confidence or knowledge (low, middle and high) is derived; interpretation of the map also promotes further study.
