PUBLIC SERVICE
DEEP , DEEP TROUBLE
Understanding the extent of an environmental wasteland .
BY LAUREN FIMBRES WOOD ’ 01
ERIC TERRILL ’ 93 , PHD ’ 98 , knew barrels of toxic chemicals had been dumped in the ocean waters between Los Angeles and Catalina Island , but the scale of the dump site was unknown . A previous study had even indicated that dichlorodiphenyltrichloroethane , or DDT , may be in some of the barrels . Then , while conducting a survey of the seafloor in the area , the sonar data began to be overwhelming , becoming impossible to count while at sea .
“ It was like trying to count stars in the Milky Way ,” says Terrill , a researcher at Scripps Institution of Oceanography . “ We soon realized that manually counting these targets just wouldn ’ t work .”
Eric Terrill ’ 93 , PhD ’ 98
Spurred by investigative reporting by the Los Angeles Times , Terrill led the March 2021 expedition aboard research vessel Sally Ride using advanced underwater robotics and side-scan sonar to locate the barrels dumped on the seafloor decades ago . They ended up needing to use machine learning to develop an algorithm to count objects for them , yielding more than 27,000 targets with high confidence to be classified as a barrel and an excess of 100,000 total debris objects on the seafloor — and this was just at one of two known dumpsites .
Historical records show that between 1947 and 1961 , an estimated half a million barrels of DDT-laced sludge and other chemical waste may have been dumped offshore . While unfathomable now , no regulations had been put in place to ban such dumping until 1972 , when the Marine Protection , Research and Sanctuaries
Photos : Schmidt Ocean Institute
Act , also known as the Ocean Dumping Act , was created .
UC Santa Barbara geochemist , David Valentine ’ 95 , MS ’ 96 , had also heard tales of historic dumping and , in 2011 and 2013 , used a combination of submersible vehicles to find scores of barrels — including some which appeared to be leaking . His 2019 research publication on these findings also heightened awareness .
“ The fact that there could be half a million barrels down there … We owe it to ourselves to figure out what happened , what ’ s actually down there and how much it ’ s all spreading ,” Valentine told the Los Angeles Times .
As the extent of this dumpsite becomes clearer , scientists are on a quest to understand the fingerprint of the DDT in the marine ecosystem and determine how to best mitigate the problem . For instance , the discovery of these barrels may help provide context to recent findings of DDT in
14 TRITON | WINTER 2022