Quantifying the U.S. Coast Guard Ecological Risk Assessment on Diluted Bitumen

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Environmental Sciences
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Nielsen, Eric

As the Federal On-Scene Coordinator in the coastal zone, the U.S. Coast Guard is charged with preparing for and responding to oil and hazardous material spills throughout our nation’s waterways to protect human health and the environment. As the scientific community continues to amass technical knowledge of unconventional crude oils, the response community must continually assess the environmental risks and update spill response plans. This research seeks to quantify the recent U.S. Coast Guard Sector Delaware Bay Consensus Ecological Risk Assessment (CERA) on diluted bitumen (DB) and compare the toxicity of DB to conventional crude (CC) oils. At the height of the domestic energy renaissance, 103,000 barrels of DB were transported via railcar each day to five refineries throughout the Delaware Bay tri-state region. To assess the emerging risks associated with DB oil spills and develop the most effective response plans, Sector Delaware Bay completed a CERA in 2016. The CERA qualitatively compared and evaluated response actions and impacts to hypothetical spills in Mantua Creek, a freshwater tributary of the Delaware River, and in the brackish Delaware River. Following the U.S. Environmental Protection Agency’s (EPA) three-phase approach to Ecological Risk Assessments, the CERA is adapted and quantified with two new data sets from Natural Resources Canada (NRCan) and the University of Quebec National Institute of Scientific Research (INRS). Utilizing Alberta Mixed Sweet Blend (CC) and Cold Lake Blend (DB) molecular composition and weathering data from NRCan and preliminary Fathead Minnow (Pimephales promelas) toxicity data from INRS, exposure and stressor-response profiles to DB are created. The ecological risk of Fathead Minnow exposure to DB spills is characterized and compared to the risks associated with CC oil spills. Based on the risk characterizations, recommendations are provided on how CC spill response techniques should be altered for DB spills to reduce the risk to mid-water zone fish.

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