FACTORS AFFECTING MARINE HYDROCARBON EMISSIONS IN AN AREA OF NATURAL SEEPS AND ABANDONED OIL WELLS - SUMMERLAND, CALIFORNIA

ABSTRACT A video-monitored oil-seep capture tent and an intertidal seep tank were developed and deployed to quantify emissions in shallow (5-m) nearshore waters and at an intertidal location at Summerland Beach, California. At two sites, where bubbles appeared clear, gas to oil ratios were 105:1; at a site where bubbles were dark, gas to oil ratio was 8.4:1. Nearshore oil emissions were conservatively estimated at 0.8 L dy’1. The size distribution of oily bubbles sharply peaked at 1500 µm, and the gas to oil ratio varied between bubbles. Oil affected the bubble's buoyancy and hydrodynamics. Time series of seabed emissions showed oil was mostly released in pulses. Several mechanisms that may cause variability in oil emissions were proposed. Intertidal oil emission were estimated a 12 L dy−1. Also, beach surveys showed less than trace amounts of beached oil and no oiled fauna over a 19-month period.