Aromatic Hydrocarbon Concentrations in Seawater: Deepwater Horizon Oil Spill

Abstract

ABSTRACT When oil is spilled or discharged into the marine environment, the chemistry and chemical concentrations of oil constituents in seawater become the target of intensive investigation as these ephemeral data are crucial to toxicity and injury assessments. The preliminary results from more than 6000 offshore water samples (>3 miles from shore) from the Deepwater Horizon (MC252) oil spill are discussed. Total Polycyclic Aromatic Hydrocarbon (TPAH) concentrations in whole, unfractionated water samples were found at concentrations ranging from not detected (ND) to 146,000 μg/L (parts per billion), with a geometric mean of 0.007 ppb. Eighty-five (85) percent of all samples were at TPAH concentrations of <0.1 ppb, essentially at or near background levels. Total Petroleum Hydrocarbons (TPH) ranged from ND to 6130 mg/L (parts per million), with a geometric mean = 1.09 ppb. Concentrations of TPAH attenuated rapidly with distance from the release point (the wellhead) and were seen to reach <1.0 ppb within 15...