Implementation of the TRIAD approach for the ecological risk assessment of an old lead mine
Abstract
Site specific ecological risk assessment of soil contamination goes with intrinsic difficulties. Obvious ones are heterogeneity of soil properties, landscape, local communities, diversity and ecosystem structure, and contamination nature and pressure. In this context, the International Standard ISO/DIS 19204 “Soil quality – Procedure for site specific ecological risk assessment of soil contamination (Soil quality TRIAD approach)” describes in a general way the application of three combined lines of evidence (chemistry, ecotoxicology and ecology). The TRIAD includes different tiers in which each consecutive tier is increasingly fine-tuned according to the site-specific situation. Data collected on an open pit mine operated during 60 years and which the activities stopped about 100 years ago as been used to evaluate the ease and efficiency in using the different tiers of TRIAD. The pollution pressure still present in the mine is of metallic origin (mainly Pb, Cd, Zn) and 5 areas with different levels of contamination, vegetation and quantites of organic matter in soil were chosen. It was possible to apply the tier one tools on every selected locations. The combined use of chemical concentration in soil (Chemistry), plant screening test (Toxicology) and simple vegetation survey (Ecology) were sufficient to asses the risk on some of the areas. In consequence, some of the expensive and time consuming data collected in these locations were not needed to assess the risk. On other locations, uncertainties were still too great and the implementation of higher tiers was needed. The focus during this applied case was on the outcome of the TRIAD method in order to obtain practicable results according to the complexity of the study. It reveals that for some locations, the use of TRIAD method can save financial and time ressources. The use of the highest tier on particularly complex zones will need additionnal datas, future investigations are planned for the year 2016.
Origin : Files produced by the author(s)