Image caption: Example munitions surveyed by the Remotely Operated Vehicle (ROV) during the 2023 seafloor survey of the San Pedro Basin. Credit: Scripps Institution of Oceanography/UC San Diego.
As part of ongoing efforts to understand the scale of the environmental impact from industrial waste dumping off the coast of Southern California, researchers from UC San Diego’s Scripps Institution of Oceanography revisited two industrial undersea dumpsites in April 2023 to identify objects discarded on the seafloor.
Led by Scripps oceanographers Sophia Merrifield and Eric Terrill, the 2023 survey used a deep water autonomous underwater vehicle (AUV) with state-of-art synthetic aperture sonar and a remotely-operated vehicle (ROV) with an HD video camera, both capable of working up to full ocean depth of 6,000 meters (19,600 feet). The expedition took place with support from the U.S. Navy’s Supervisor of Salvage and the Office of Naval Research.
Between the 1930s and 1970s, the site was a known location for industrial dumping, including byproducts from the manufacturing of the pesticide DDT, and was initially surveyed using robotic vehicles by the same team in April 2021. The goal of the second survey was to extend maps of the seafloor using higher resolution acoustic sonar imaging techniques, to apply video imaging systems to classify objects in a previously mapped debris field, and to collect observations of deep sea ocean currents. The 2023 survey mapped 350 square kilometers (135 square miles) and recorded more than 300 hours of video footage.
The 2021 survey, published in Environmental Science and Technology, documented thousands of barrel-sized objects organized in lines across the basin. Imagery collected in 2023 along debris lines found the majority of the objects to be multiple types of discarded military munitions and pyrotechnics. Barrels from the legacy of industrial dumping, and several old fishing vessels were also found. The barrels on the seafloor from the legacy of industrial dumping were found to be concentrated in two locations, and barrels were not pervasive across the dump site.
“The resolution of the sonar provided by the U.S. Navy Supervisor of Salvage provides us an unprecedented map of the seabed which will take some time to fully appreciate and analyze,” said Terrill.
About Scripps Oceanography
Scripps Institution of Oceanography at the University of California San Diego is one of the world’s most important centers for global earth science research and education. In its second century of discovery, Scripps scientists work to understand and protect the planet, and investigate our oceans, Earth, and atmosphere to find solutions to our greatest environmental challenges. Scripps offers unparalleled education and training for the next generation of scientific and environmental leaders through its undergraduate, master’s and doctoral programs. The institution also operates a fleet of four oceanographic research vessels, and is home to Birch Aquarium at Scripps, the public exploration center that welcomes 500,000 visitors each year.
About UC San Diego
At the University of California San Diego, we embrace a culture of exploration and experimentation. Established in 1960, UC San Diego has been shaped by exceptional scholars who aren’t afraid to look deeper, challenge expectations and redefine conventional wisdom. As one of the top 15 research universities in the world, we are driving innovation and change to advance society, propel economic growth and make our world a better place. Learn more at ucsd.edu.