Apr 302021

Thousands of barrels of what could be DDT discovered in survey off Palos Verdes Peninsula

Scientists discovered barrels of industrial waste beginning in 2011 off the Palos Verdes Coast. From March 11 through 24. UC San Diego’s Scripps Institution of Oceanography and National Oceanic and Atmospheric administration took a survey to “verify how barrels potentially containing DDT-Contaminated waste” that are sitting at the bottom of the ocean. (Photo Courtesy of David Valentine/ RV Jayson)
Scripps Researchers surveying the seafloor for discarded DDT barrels aboard the R/V Sally Ride
Scripps Researcher board the research vessel Sally Ride deploy the REMUS 6000 autonomous underwater Vehicle(AUV) to survey the seafloor for the discarded barrels. March 2021 (Credit: Cripps Institution Oceanography at UC San Diego.

More than 27,000 barrels of what potentially could be the toxic chemical DDT are on the ocean floor between the Palos Verdes Peninsula and Catalina Island, according to a survey scientists from UC San Diego’s Scripps Institution of Oceanography released Monday, April 26.

The survey, conducted from March 10 to 24, mapped more than 36,000 acres of seafloor — at depths of up to 3,000 feet, and about 12 miles offshore from the Palos Verdes Peninsula and eight miles from Catalina — in an area where scientists had previously discovered an accumulation of DDT.

DDT has concerned scientists for decades, with high levels of the cancer-causing insecticide being found in dolphins and sea lions, Scripps said in a Monday press release.

A team of 31 scientists, engineers and others conducted the survey, done in conjunction with the National Oceanic and Atmospheric Administration and the National Oceanographic Partnership Program. The team discovered more than 100,000 objects on the seafloor, which the project’s leaders said they believe are man-made; the surveyors “have a high degree of confidence” that 27,000 of those are barrels.

But the mapping sonars cannot determine the contents of the barrels, said Eric Terrill, chief scientist of the expedition and director of the Marine Physical Laboratory at Scripps Institution of Oceanography. Still, the surveyors, Terrill said, were surprised at the extent of the debris field.

“Looking at the historical records, how those (dumpings) had potentially occurred for decades on a monthly basis, it shouldn’t have been a surprise to us,” he said during a virtual press conference Monday afternoon. “But it was still just not anything I had really wrapped my head around in terms of envisioning what we might actually find.”

A number of industrial companies were involved in dumping harmful chemicals from the 1930s until 1972, when the federal Marine Protection, Research and Sanctuaries Act was enacted.

One of those companies was the long-defunct Montrose Chemical Corporation, which manufactured, packaged and distributed DDT from 1947 to 1982 in an unincorporated area of Los Angeles County, near Torrance. The company reportedly dumped the pesticide into the ocean for decades, impacting the 17-mile Palos Verdes Shelf.

DDT is a synthetic insecticide developed in the 1940s and banned in 1972 for its detrimental impacts on humans and wildlife.

The U.S. Environmental Protection Agency in 1989 identified the area around the Montrose plant as a Superfund site, defining it as one of the nation’s most toxic collections of pollution. State and federal agencies reached a $140 million settlement in 2001 with Montrose, which included paying for the Palos Verdes Reef Restoration Project that was completed last year.

Discovering the barrels

But in 2011 and 2013, David Valentine, a professor of microbiology and geochemistry at UC Santa Barbara, teamed with fellow scientists to use a remotely operated vehicle to explore a small area off the Palos Verdes Peninsula. They discovered dozens of barrels.

Valentine, in a Monday interview, responded to the Scripps findings by saying he was “shocked that the dumping was so widespread.”

“It was very clear from the Scripps data,” he said, “that they just dumped where they wanted to dump.”

Valentine’s expedition was inspired by a study by Allan Chartrand, who was a regulatory scientist with the California Regional Water Quality Control Board. Chartrand was able to get access to Montrose company records that showed there could be upwards of 500,000 barrels of toxic substances, but the report was ignored, Valentine said in an interview last month.

Valentine’s study discovered more than 60 barrels in various states of disrepair. Because of this, his team took samples and reportedly found extremely high concentrations of DDT, as well as some petroleum-derived compounds.

The peak sample, Valentine said, had 40 times the highest concentration of DDT surface sediment contamination found on the Palos Verdes Shelf.

Valentine published a paper on the results in 2019.

That study said the federal government’s Superfund site did not include the ocean disposal of an estimated 2,000 to 3,000 barrels per month, from around 1947 to 1961, equaling 1 million gallons of waste per year.

State and federal officials eventually took notice and helped launch the findings released Monday.

The 60 barrels Valentine and his team discovered were used as a reference point when the Scripps team when looking for barrels, according to a press release announcing the most-recent survey.

“The data from the Valentine expedition were used to ground-truth our algorithms,” said Sophia Merrifield, a researcher at Scripps who has been leading the data analytics. “Location, size, and acoustic brightness are tracked for each target detected and used to characterize patterns and densities of the debris field.”

What’s next

The Scripps team says they hope the survey results will lead officials to address the consequences of the historical chemical dumping. Testing will be needed to determine whether the barrels still contain harmful chemicals.

“Our contribution to that piece of the puzzle,” Terrill said, “is really to start providing a large wide area map to say where should we begin sampling.”

And sampling could ultimately help answer another question: Could these barrels be to blame for worrisome levels of DDT found in some sea life.

A 2015 study, for example, found a “high abundance of DDT and other man-made chemicals in the blubber of Bottlenose Dolphins that died of natural causes,” the Scripps press release said. High levels of DDT in “top predators feeding in Southern California water has been known for some time,” that study also said, according to the press release.

“The extent of the dumping ground helps to explain some of these previous observations,” Lihini Aluwihare, Scripps chemical oceanographer and professor of geosciences who co-authored that study, said in a written statement.

“These results also raise questions about the continued exposure and potential impacts on marine mammal health,” Aluwihare, who was not part of the mapping survey, added, “especially in light of how DDT has been shown to have multi-generational impacts in humans.”

Via PVNews

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