Metals present many challenges to those responsible for assessing hazard and risk to aquatic organisms. Past studies have shown that neither total nor dissolved concentrations of metals are good predictors of their potential effects on ecosystems. Indeed, several physico-chemical water characteristics, such as dissolved organic carbon (DOC), pH and hardness can modify toxicity with several orders of magnitude.
Accounting for the bioavailability of metals, using techniques such as the Biotic Ligand Model (BLM), resolves some of these difficulties. The BLM approach is currently considered as state-of-the-art for predicting metal bioavailability because it integrates existing knowledge about metal speciation in the solution surrounding the organism and the interactions between metal ions and competing ions at the binding sites on the organism-water interface (e.g. epithelial cells in fish gill tissue).
The Lead Chronic Biotic Ligand Model Tool (Lead BLM Tool*) is a programme for anybody interested in bioavailability-based approaches for assessing the chronic effects of lead in the freshwater aquatic environment and combines bioavailability models with detailed species sensitivity distribution (SSD) analyses to derive hazard concentration of lead for a given water body.
The tool is a free online resource that was produced under contract of ILA by ARCHE Consulting cvba using biotic ligand models developed to describe lead toxicity by GhEnToxLab, Ghent University (Belgium) and the chemical speciation codes used in Visual Minteq (KTH, Sweden). A detailed technical user guide has been developed that provides background information on the lead biotic ligand model and step-by-step instructions for installing the tool.