A self-evaluation method to attribute sound bio-values based on in situ ecotoxicological monitoring

Microbial, plant and animal species were examined within the framework of the ADEME Bioindicator Program in France that involves the monitoring, characterization and risk assessment of soils from various sites. Whenever any of the selected species under study were not found in all of the sampling areas of a given site, the data were difficult to analyze. It is explained how discrepancies in the data analysis may arise depending on the way the values of the biological parameters are taken into account: as a biomarker to assess values for each species in different areas, or as bioindicator to evaluate the number of species impacted in each area. We present a method to prevent discrepancies in interpretation in which a bio-value (“soil quality”) is attributed to various areas, allowing them to be ranked. The method also provides an evaluation of the soundness of the results and the resulting ranking, and no areas need to be assigned a priori as “control” or “contaminated” areas.In the framework of the ADEME Bioindicator Program, the leaf C18:3/(C18:0 + C18:1 + C18:2) fatty acid ratio was used as biological parameter. The experimental data obtained from two sites, in which not all plant species under study were found in all sampling areas, were analyzed by the above-mentioned method. The method proved usable to calculate a sound bio-value for each area in both sites and to rank them. Comparison of data demonstrated lower bio-values for the soil in the four areas within the industrial wasteland than for that in the two areas located just outside it. The soundness of the scoring obtained in the second site demonstrates that coherent results could also be obtained with plant species harvested in areas several kilometers apart and displaying varying soil properties.