The seafloor off the Palos Verdes Peninsula may contain low levels of radioactive materials, according to new research, which also confirmed previous reports that the harmful insecticide DDT is spread across the ocean there at high concentrations.
There is only circumstantial evidence for the cause of the radioactive materials, though nuclear testing and waste disposal are among the potential culprits, researchers said this week. Yet, the now-banned DDT is potentially the bigger ecological threat, researchers said — perhaps even being the reason bald eagles disappeared from Catalina Island for a time.
Those findings were published on Wednesday, Feb. 21, in the journal Environmental Science & Technology. The research that culminated in the journal article represents another step in the evolution of marine scientists’ understanding of the contaminants that litter the seafloor off the Peninsula — a process that began more than a decade ago.
Researchers now have “indirect circumstantial evidence” that low-level radioacting waste was dumped in the Pacific Ocean by the same now-defunct company that disposed of DDT in the Peninsula waters, said David Valentine, one of the article’s authors.
But even with this new evidence, the expanse of DDT “worries me quite a bit more ecologically” than the radioactive materials, Valentine said. Valentine is a professor of microbiology and geochemistry at UC Santa Barbara — and the scientist whose discovery of barrels off the Peninsula, initially thought to contain DDT, launched years of study into ocean contaminants there.
“I think that we have to recognize that, well, it’s disturbing and it’s not good to dump low-level radioactive materials into the ocean,” Valentine said in a phone interview this week. “(But) it’s probably substantially worse to dump large amounts of DDT waste from an ecological effects perspective.”
The greatest harm from DDT, Valentine said, is that it “biomagnifies.”
Biomagnification, according to National Oceanic and Atmospheric Administration, is when toxic chemicals such as DDT get dumped into the ocean and cause health issues in wildlife, from disease to birth defects.
That happens through a simple, yet destructive, process. Toxins that settle on the seafloor end up in the food chain and works their way up. Eventually, according to the NOAA, “higher-level predators — fish, birds and marine mammals — build up greater and more dangerous amounts of toxic materials than animals lower on the food chain.”
“(Biomagnification) can impact a whole host of animals,” Valentine said. “We’re seeing (that) now with California sea lions, with California condors. There’s so much DDT that has been dumped off California, that we’re seeing effects in those animals.”
Valentine and a team of scientists initially discovered more than 60 barrels on the ocean floor in 2011 and 2013 while exploring the Peninsula seafloor with a remotely operated vehicle.
Since that initial discovery, the research has grown and scientific understanding has become more complex.
In 2021, for example, survey researchers from UC San Diego’s Scripps Institution of Oceanography discovered approximately 27,000 barrels on the ocean floor. They, like Valetine, initially thought the barrels potentially contained DDT. The insecticide, which has been banned for years, had been legally dumped by a local company, the now-defunct Montrose Chemical Corporation, for decades.
But in January, Scripps discovered that those barrels were mostly discarded World War II-era military munitions. A whale graveyard was also found.
The Scripps survey mapped 135 square miles of the San Pedro Basin, about halfway between the Palos Verdes Peninsula and Catalina Island. The technology that allows ocean-floor mapping has advanced so much in just a few year that scientists could now distinguish between barrels and munitions.
But just because those barrels did not contain DDT does not mean the insecticide wasn’t present off the Peninsula. Rather, scientists discovered in 2022 that until regulations curtailed the practice, DDT had been directly into the ocean for years.
“Substantial amounts of DDT remain in these sediments, which are largely unaltered after more than 70 years,” according to the Wednesday journal article, titled “Disentangling the History of Deep Ocean Disposal for DDT and other Industrial Waste off Southern California.”
Valentine is a corresponding author of the article. Other scientists from UC Santa Barbara, Oleolytics, LLC, USC’s Earth science department and elsewhere also contributed to the article.
The Environmental Protection Agency, according to the article, discovered 15 offshore dump sites for disposing “radioactive wastes, refinery and oil drilling wastes, chemical wastes, military munitions, filter cakes, and refuse.”
Montrose had legally dumped DDT from 1948 to around 1961, according to the article.
Montrose contracted with California Salvage Company to dispose of the “strong acid waste offshore and discharge it into the ocean” by barge, the article said.
“Located immediately offshore from the Ports of Los Angeles and Long Beach,” the article said, “the San Pedro Basin received substantial input of these wastes leading to high DDT concentrations recorded in select sediment samples.”
Montrose, based near Torrance, built an acid recycling plant, which began the decline of Cal Salvage waste dumping for the chemical company.
“There was no record of ocean disposal of Montrose sulfuric acid wastes after 1961,” the article said, “the same year Cal Salvage’s operation became regulated by a regional water quality board and a formal dumpsite was assigned to them.”
But Cal Salvage, the article said, continued dumping industrial waste for other clients. Montrose reportedly disposed of 1.5 million gallons of other industrial wastes from 1965 to 1972.
Cal Salvage, meanwhile, continued ocean disposal until the mid 1970s when permitting was not allowed, Valentine said.
No samples of the barrels on the seafloor provide evidence of radioactive waste disposal, the article said, but there is circumstantial evidence that such dumped may have occurred — and doing so may not have run afoul of the law.
“The historical record,” the article said, “points to a scenario in which Cal Salvage was potentially able to openly operate as an offshore radioactive waste disposal company without triggering oversight.”
The trail, though, is cold, Valentine said.
“I don’t actually know when, as a corporation, it dissolved,” Valentine said of Cal Salvage, “or how they were even set up.”
But there is evidence in the sediments that the peak of offshore disposal was the mid 1950s. The evidence, though, also includes fallout from nuclear weapons testing.
There was a “low level fallout of certain radioisotopes all over the planet” from when nuclear testing was conducted above ground by the United States and the Soviet Union.
Researchers, Valentine said, compared the peak concentration of DDT and the amount of radioisotopes to determine when the bulk of DDT was dumped. Carbon-14 dating was also a component used in the dating.
“It was a lot of detonations that released these nuclear products directly into the atmosphere,” Valentine said. “And they then spread on winds as small particles until they settled out. And they settled out all over the planet.”
Radioactive waste, though, does not have the same impact on the environment, Valentine said, since there is “no concentrating effect” like with DDT and the isotopes of the radioactive waste “would have decayed away.”
“There was this offshore disposal of the DDT and that remains largely as DDT today,” Valentine said, “and it’s buried down to two inches two and a half inches beneath the seafloor.”
There are also derivatives of DDT that have broken down and can still be found closer to the surface of the seafloor, Valentine said.
DDT has had a significant impact on wildlife, Valentine said — including on the bald eagle.
The bald eagle effectively disappeared from Catalina Island in the 1950s, Valentine said, in large part because of DDT, even though “we don’t have direct evidence for it.”
There was abundant DDT that was “dumped into the surface water, into the ecosystem,” where the bald eagle got its food, he said.
DDT, he said, is “well known for its properties of eggshell thinning.”
The bald eagle has since been reintroduced to the island.
Studies still need to be done on the World War II munitions that were recently found, Valentine said.
“I’m not aware of of anything in them that would have the kind of effects that DDT would,” he said, “but I think it’s still worth looking into.”
That’s why U.S. Sen. Alex Padilla and Rep. Salud Carbajal, along with 20 other California lawmakers, said in a press release this week that they are urging the Office of Management and Budget to include “robust, long-term funding” to research DDT and other harmful chemicals dumped into the ocean, as well as the impact on the Southern California environment, and human and wildlife health.
The late Sen. Dianne Feinstein and Padilla helped secure nearly $12 million over two fiscal years, 2022 and 2023, to help survey Southern California DDT dumpsites, according to the press release.
“While DDT was banned more than 50 years ago, we still have only a murky picture of its potential impacts to human health, national security and ocean ecosystems,” the lawmakers said in the press release. “We encourage the administration to think about the next 50 years, creating a long-term national plan within EPA and NOAA to address this toxic legacy off the coast of our communities.”
Source: Orange County Register
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