Metal content in Garonne basin rivers: Evidences for a general non point contamination of anthropogenic origin

Abstract
Metal contents were measured in the main rivers of the Garonne basin (SW France). Metal concentrations are shown to be slightly lower but nevertheless comparable to those of other Western European rivers such as the Seine river. As these rivers, the bulk river load show typical metal enrichments (estimated through the enrichment factor, EF=(Cx/CAl)river/(Cx/CAl)cc) by factors of 10 and even 100 for some metals, relatively to the mean continental crust composition. A set of arguments is presented assigning the origin of this metal enrichment for most metals to a general non point contamination of anthropogenic origin through atmospheric inputs and soils transfer.