Quantified Marine Oil Emissions with a Video-Monitored, Oil Seep-Tent

A video-monitored oil capture tent was developed and deployed during two field trips to quantify oil emissions from several sites in nearshore waters off Summerland Beach in Santa Barbara County, California, at a water depth of ∼5 m. The tent was a tall, inverted polyvinyl chloride plastic cone, which funneled oil into a video-observed sample collection jar. Sample jars were periodically retrieved and analyzed to determine oil and gas emissions at two seeps not associated with physical structures, and a suspected abandoned oil well, designated S-3. Oil and gas emissions at the seeps were ∼1 ml day −1 and ∼90 L day −1 , respectively. At the S-3 site, emissions were 51 ml oil day −1 and 0.35 L gas day −1 . The size distribution of bubbles at S-3 was sharply peaked at 1500-μm radius, and bubbles rose significantly slower than equivalent size non-oily bubbles, demonstrating the effect of oil on buoyancy loss. A method was developed to estimate from the measured rise velocities the oil-to-gas ratio of each bubble, calibrated with the sample analysis oil and gas fluxes. Autocorrelation showed strong peaks at 64.3 s and 120.0 s period, which were likely related. Other autocorrelation peaks at multiples of 8.2 s corresponded to Fourier spectrum peaks at 8 s and 23.4 s, and were proposed to relate to wave swell-induced surge. Other spectral peaks were observed at 4.9 s, 13.0 s, and 45-50 s period.