Sequestration of mercury and PCBs in sediments via amendments
« All Publications

Chemicals such as polychlorinated biphenyls (PCBs), and mercury (Hg) are present as contaminants in sediment at numerous sites globally.

Amendments are sometimes used in conjunction with Monitored Natural Recovery (MNR) to accelerate chemical sorption, sequestration, or biodegradation processes, and to reduce bioavailability and toxicity. To gain regulatory acceptance for this Enhanced MNR (EMNR) method, the site-specific physical, biological and chemical processes that reduce bioavailability or degrade contaminants must be well understood, demonstrated, and quantified in laboratory treatability tests and in field pilot tests.

Laboratory treatability testing was conducted to demonstrate the potential for a variety of in situ amendments to reduce concentrations of Hg, methylmercury (MeHg) and PCBs in water mixed with sediment from a contaminated sediment site in a tidal estuary with brackish water under simulated anaerobic conditions over eight weeks. The concentrations of PCBs, Hg and MeHg in the aqueous phase were measured and the concentrations in the treated microcosms were compared with the concentrations in the controls. Results of the testing demonstrated that significant reductions in the concentration of PCBs, Hg and MeHg in water in contact with the sediment could be obtained with the specific amendments evaluated in the test. A combination of powdered activated carbon and iron amendments was successful in reducing the concentrations of PCBs in the simulated porewater by over 99% relative to controls and reducing Hg and MeHg by 89% and 82% relative to controls, respectively. Further testing is underway to further assess the bioavailability of Hg in post remediated sediments versus control sediments.

Read more about this...

Publication Summary

  • Geosyntec Authors: Karen Bechard
  • All Authors: Karen Bechard
  • Title: Laurentian Society of Environmental Toxicology and Chemistry (SETAC) 21st Annual General Meeting & Conference entitled "Watershed Science Under Multiple Stressors
  • Event or Publication: Event
  • Practice Areas: Contaminated Sites
  • Citation: Laurentian Society of Environmental Toxicology and Chemistry (SETAC) 21st Annual General Meeting & Conference entitled "Watershed Science Under Multiple Stressors" at the University of Waterloo in Ontario on June 24, 2016.
  • Date: 2016
  • Location: University of Waterloo in Ontario