When Oil is the Lesser of Two Evils: Comparative Risk of the Shipwreck EMPIRE KNIGHT Cornell J. Rosiu, First Coast Guard District - Incident Management, 408 Atlantic Ave, Boston MA 02110Stephen M. Lehmann, NOAA - Office of Response and Restoration, 10 George St, #220, Lowell, MA 01852David M. Sherry, Center for Law and Military Operations, Charlottesville, VA 22903Wyman W. Briggs, USCG - Sector Northern New England, 259 High St, South Portland, ME 04106Peter J. Blanchard, Maine DEP – Div. of Response Services, #17 State House Station, Augusta, ME 04333At the height of WWII in February of 1944, the 428-ft British ship EMPIRE KNIGHT ran aground on Boon Island Ledge off York, Maine during a storm. It broke in two and sank with the stern section in 243-ft of water where it remains today. Her hull contained 10,000-bbls of diesel fuel oil, military tank and locomotive parts, 5-in cannon shells and 16,000-lbs of elemental mercury stored in 221 glass and steel carboys. This poster summarizes the wreck disposition and its environmental assessment and ongoing monitoring. In 1993, the U.S. Coast Guard (USCG) oversaw an emergency removal of 1,200-lbs elemental mercury through a hole cut in stern cargo hold #5 representing <10% of the cargo of elemental mercury. Much of the mercury is assumed to have migrated to the lower portion of the shipwreck beneath a cargo of military hardware and live ammunition. Since much of the mercury is believed to remain on-site, a permanent safety zone was established in 1995 within a 1000-yd radius prohibiting activities such as commercial salvage that could spread contamination. Mercury is a priority pollutant that accumulates in marine life and can bio-magnify in the environment. Results of bio-monitoring in 1998, 2004 and 2012 using blue mussels (Mytilus edulis) supported previous findings and indicated mercury does not pose unacceptable risk to human health or the environment. Moreover, average concentrations of mercury across the three years are less than averages in mussels sampled from 2007 to 2009 in areas of the Gulf of Maine coast that have no known point source of mercury contamination. NOAA ranked EMPIRE KNIGHT 12th among 13 RULET shipwrecks in USCG District 1 with “medium” risk of oil discharge. Disturbing the wreck to recover oil onboard has the potential to spread contamination and make the mercury more bioavailable.

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