Applying the Triad method in a risk assessment of a former surface treatment and metal industry site

Abstract

With a greater focus on soil protection in the E.U., the need for ecological risk assessment tools for cost-effective characterization of site contamination is increasing. One of the challenges in assessing the risk of soil contaminants is to accurately account for changes in mobility of contaminants over time, as a result of ageing. Improved tools for measuring the bioavailable and mobile fraction of contaminants is therefore highly desirable. In this study the Triad method was used to perform a risk characterization of a former surface treatment and metal industry in Eskilstuna, Sweden. The risk assessment confirmed the environmental risk of the most heavily contaminated sample and showed that the toxic effect was most likely caused by high metal concentrations. The assessment of the two soil samples with low to moderate metal contamination levels was more complex, as there was a higher deviation between the results from the three lines of evidence; chemistry, (eco)toxicology and ecology. For the slightly less contaminated sample of the two, a weighting of the results from the ecotoxicological LoE would be recommended in order to accurately determine the risk of the metal contamination at the sampling site as the toxic effect detected in the Microtox® test and Ostracodtoxkit™ test was more likely to be due to oil contamination. The soil sample with higher total metal concentrations requires further ecotoxicological testing, as the integrated risk value indicated an environmental risk from metal contamination. The applied methodology, the Triad method, is considered appropriate for conducting improved environmental risk assessments in order to achieve sustainable remediation processes.