Environmental implications of the use of sulfidic back-bay sediments for dune reconstruction - Lessons learned post Hurricane Sandy.

Some barrier-islanddunes damaged or destroyed by Hurricane Sandy's storm surgesin October 2012 have been reconstructed using sediments dredged from back bays. These sand-, clay-, and iron sulfide-rich sediments were used to make berm-like cores for the reconstructed dunes, which were then covered by beach sand. In November 2013, we sampled and analyzed partially weathered materials collected from the cores of reconstructed dunes. There are generally low levels of metal toxicantsin the reconstructed dune materials. However oxidation of reactive iron sulfidesby percolating rainwater produces acid-sulfate pore waters, which evaporate during dry periods to produce efflorescentgypsum and sodium jarositesalts. The results suggest use of sulfidic sediments in dune reconstruction has both drawbacks (e.g., potential to generate acid runoff from dune cores following rainfall, enhanced corrosion of steel bulwarks) and possible benefits (e.g., efflorescentsalts may enhance structural integrity).