Soil and waste analysis for environmental risk assessment in France

In France today, analysis of soil and waste after digestion by strong acids is a technique used for the estimation of environmental risks due to soil pollution and spreading of wastes on cultivated soils. The technique of digestion by strong acid accounts for total or ‘near total’ content of As, Cd, Cr, Cu, Hg, Ni, Pb, Se and Zn. Risk management based on these methods aims to minimize the risks, since the concentration limits are derived from the geochemical levels. However, this method of analysis gives no idea of the extent to which elements are really transferable or bioavailable. Analytical methods based on partial extraction are used to discern deficiencies in B, Cu, Fe, Mn and Zn in soil. These extractions are carried out using boiling water and EDTA or DTPA solutions. The extraction methods have been standardized for use in agriculture, but have not been tested for assessing the risks due to the pollution by trace elements. One partial extraction method has been standardized for the analysis of wastes. It uses successive water extractions. Researchers have studied different partial extraction methods for estimating the bioavailability of mineral pollutants. Some of them gave results which correlated well with the amounts taken up by plants. However, at present, no general frame of reference has yet been established for the interpretation of results on a broad scale.