Assessment of metal(loid) concentrations using diffusive gradient thin (DGT) films in marine, freshwater and wetland aquatic ecosystems impacted by industrial effluents

Bioavailable metal(loid)s in aquatic ecosystems pose potential ecological risks to aquatic organisms. In situ passive sampling using diffusive gradient thin (DGT) films is an effective technique to measure bioavailable contaminants in aquatic ecosystems. Contaminated sediments impacted by industrial effluents in Nova Scotia, Canada are poised for remediation following detailed site characterization. This study explored used DGTs to measure bioavailable contaminants at the sediment/water interface to inform potential ecological risk. Eighty DGTs discs were deployed in one marine and three freshwater sites. DGTs were used to measure metal(loid), total mercury (THg) and methylmercury (MeHg) concentrations within 5 cm of the sediment/water interface in marine and freshwater sites to help with site characterization. Of eighty discs, forty contained chelex binding gel (for As, Cd, Cr, Cu, Pb and Zn analysis) and forty contained 3-mercaptopropyl-functionalized silica (MFS) binding gel for THg and MeHg analysis. Bioavailable metal(loid) and THg concentrations were low and MeHg concentrations were below detection levels across all sites. Results suggest that ecological risk to aquatic organisms is low. Use of in situ passive sampling techniques may help inform risk management decision making during remediation planning.