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San Diego researchers probe underwater chemical dump

San Diego scientists are among researchers who will take a closer look at a massive underwater dump site in the deep ocean waters between Catalina Island and Los Angeles.

The National Oceanic and Atmospheric Administration is distributing $5.6 million that will fund a number of research projects aimed at better understanding the dump area.

Underwater scans show more than 27,000 decaying barrels on the ocean floor.


Shipping records from one chemical disposal company that worked with DDT producing Montrose Chemical Corporation of California, show 2,000 barrels of DDT laced sludge were dumped at the underwater site every month for 15 years.

Dichlorodiphenyltrichloroethane, or DDT, is an artificial chemical that was used to control insect populations from the 1940s to the 1960s. The chemical is considered dangerous to human health and remains in the environment and animal tissues for a long time. It was banned in the United States in 1972.

Other companies also dumped chemicals there and Scripps researchers think some of the drops involved raw liquid chemicals that were not contained in barrels.

Researchers mapped 36,000 acres of the notorious dump site in the San Pedro Basin with underwater drones. They estimate the entire dumping ground could be twice the size of Manhattan.

Scientists from the Scripps Institution of Oceanography and UC Santa Barbara are among those hoping to learn how the nearby underwater habitat has been affected by the toxic dump in the San Pedro Basin.


“We’re still trying to figure out how much DDT and related toxins were in those barrels and dumped in that barrel field,” said Brice Semmens, a researcher at the Scripps Institution of Oceanography. “And that’s one of the very first steps in understanding what impact, in terms of toxins, is to our coastal environment.”

Underwater photographers of the debris field revealed deteriorating barrels with ominous rings in the sediment around them.

“To what extent are they penetrating into the ecosystem up to and including the creatures that we care a lot about,” said Semmens. “Whether that’s coastal fisheries or marine mammals or the fishing communities that rely upon those marine resources.”

Scientists hope additional research will help them specifically understand the environmental impact on the marine food web.

“Is this DDT that’s accumulating at these deep sites entering the marine food web at any level, specifically closest to where the dump site is,” said Lihini Aluwihare, a chemical oceanographer at the Scripps Institution of Oceanography.

Aluwihare has already identified high amounts of DDT and other chemicals in the blubber of bottlenose dolphins that died of natural causes in a 2015 study.

She hopes to develop chemical fingerprints of the contamination that will allow those signatures to be traced in the marine food web.

“We can sort of show this making its way through the food web that’s at the deep basin, into the food web that we’re more familiar with where we might catch fish or the dolphins or seals might be accessing,” Aluwihare said.

California’s two senators — Diane Feinstein and Alex Padilla — obtained the funding to help broaden the understanding of the threat from the old ocean dump site.

“Until we understand the scope of the problem, we can’t develop solutions to solve it,” Feinstein said. “That’s why we secured funding to map the region’s seafloor and test the barrels, sediment and water column.”

The studies will focus on five key areas: finding all the barrels, fingerprinting the chemicals, examining how DDT is moved by seafloor animals, checking to see if the dump’s chemicals are in other parts of the marine food web, and exploring whether microbes can help with remediation.