Estimating sub-surface dispersed oil concentration using acoustic backscatter response

• Published in: Marine pollution bulletin 2013-05, Vol.70 (1-2), p.140-146
• Main Authors: Fuller, Christopher B., Bonner, James S., Islam, Mohammad S., Page, Cheryl, Ojo, Temitope, Kirkey, William
• Format: Article
• Language: English
• Subjects: Acoustic backscatter; Acoustics; ADCP; Animal and plant ecology; Animal, plant and microbial ecology; Applied ecology; Biological and medical sciences; Dispersed oil; Droplet size distribution; Ecotoxicology, biological effects of pollution; Environmental Monitoring - methods; Fundamental and applied biological sciences. Psychology; LISST-100; Marine and brackish environment; oils; particle size distribution; particles; Petroleum - analysis; Petroleum Pollution - analysis; Petroleum Pollution - statistics & numerical data; remote sensing; Sea water ecosystems; Seawater - chemistry; suspensions; Synecology; Water Pollutants, Chemical - analysis; water pollution
• ISSN: 0025-326X; 1879-3363
• DOI: 10.1016/j.marpolbul.2013.02.025

► Using acoustic backscatter (ABS) to quantify oil concentration was evaluated. ► ABS was measured with Acoustic Doppler Current Profiler (ADCP). ► Theoretical ABS response calculated with oil droplet size distribution. ► Study found log-linear ABS responses to oil droplet volume concentration. ► Measured ABS and theoretical oil ABS demonstrated linear relationship. The recent Deepwater Horizon disaster resulted in a dispersed oil plume at an approximate depth of 1000m. Several methods were used to characterize this plume with respect to concentration and spatial extent including surface supported sampling and autonomous underwater vehicles with in situ instrument payloads. Additionally, echo sounders were used to track the plume location, demonstrating the potential for remote detection using acoustic backscatter (ABS). This study evaluated use of an Acoustic Doppler Current Profiler (ADCP) to quantitatively detect oil-droplet suspensions from the ABS response in a controlled laboratory setting. Results from this study showed log-linear ABS responses to oil-droplet volume concentration. However, the inability to reproduce ABS response factors suggests the difficultly in developing meaningful calibration factors for quantitative field analysis. Evaluation of theoretical ABS intensity derived from the particle size distribution provided insight regarding method sensitivity in the presence of interfering ambient particles.