Oral Presentation Society of Environmental Toxicology and Chemistry Australasia 2021

In situ DGT sensing of bioavailable metal fluxes to improve toxicity predictions for sediments. (#32)

Stuart Simpson 1 2 , Minwei Xie 3 , Jianyin Huang 4 , Peter R. Teasdale 4 , Wen-Xiong Wang 5 6
  1. CSIRO Land and Water, Lucas Heights, NSW, Australia
  2. Hong Kong Branch of Southern Marine Science and Engineering Guangdong Laboratory, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
  3. Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystem, College of the Environment and Ecology, Xiamen University, Xiamen, Fujian 361102, China
  4. Scarce Resources and Circular Economy (ScaRCE), STEM, Future Industries Institute, University of South Australia, Mawson Makes, Adelaide, SA 5095, Australia
  5. School of Energy and Environment, State Key Laboratory of Marine Pollution, City University of Hong Kong, Kowloon, Hong Kong, China
  6. Research Centre for the Oceans and Human Health, City University of Hong Kong Shenzhen Research Institute, Shenzhen, 518057, China

An increased risk of adverse biological effects of metals in sediments may be accompanied by high labile metal fluxes as measured by the diffusive gradients in thin films (DGT) technique. To improve the usefulness of the DGT technique for sediment quality risk assessments, we used the simpler and more cost-effective piston DGTs rather than planar DGT probes to measure bioavailable metal fluxes in naturally contaminated sediments with widely varying composition (properties, metals and concentrations) and assessed their prediction of toxicity to amphipod reproduction in a flow-through microcosm. DGT pistons were deployed in sediments under different conditions, both in the field (in situ) and in the laboratory in sediment cores (lab-equilibrated) and in homogenized sediments (lab-homogenized). We demonstrated that the metal flux toxic units, DGT-TU, measured in situ best predicted the magnitude of toxicity to amphipod reproduction. For sediments that had been highly disturbed before testing, DGT-TU were less predictive for observed toxicity, but the copper flux alone (DGT_Cu-TU) was effective, indicating copper was the primary cause of toxicity in these highly perturbed sediments.

Overall, this study demonstrated the robustness of relying on in situ measurements using the more cost-effective DGT “pistons” to predict the existence of excessive bioavailable metal concentrations and risks of adverse effects in contaminated sediments. Applying DGT in sediment quality assessments, particularly as an alternative line of evidence for screening purposes, may substantially improve the assessment effectiveness, lower the associated uncertainties, and reduce the overall costs for contaminated site management.

We dedicate this research to Professor Peter Teasdale, who passed away suddenly in 2020. Peter had played a leading role in expanding the development and application of DGT techniques. He was a kind, humble, and self-effacing person who was willing to help anyone when he could. His passing is a great loss to environmental science in Australia.