Marine life off the coast of Los Angeles may still be affected by a long-defunct DDT dump site, a report released Monday by researchers from the Scripps Institution of Oceanography at the University of California, San Diego, and San Diego State University says. It turned out that there is a sex.
In the 1940s and 1950s, the waters off the coast of Los Angeles were a dumping ground for the nation's largest manufacturer of the pesticide DDT, researchers say. This chemical is now known to be harmful to humans and wildlife.
Although legal at the time, the details of this contamination about 25 miles off the coast of Catalina Island have deeply concerned scientists and the public since it became widely known in 2020, the authors write.
Their findings, published Monday in the journal Environment Science and Technology Letters, show that deep-sea fish and sediment collected near the dump remain contaminated with numerous DDT-related chemicals.
“These are deep-sea organisms that don't spend much time on the surface, and they're contaminated with these DDT-related chemicals,” said Lihini Alwihea, professor of marine chemistry at Scripps College and co-author of the study. Ta.
“Establishing the current distribution of DDT contamination in deep-sea food webs will help us consider whether those contaminants are also moving through deep-sea food webs to species that may be consumed by humans. Build the foundation.”
According to the authors, from 1948 until at least 1961, barges contracted by DDT manufacturer Montrose Chemical Corporation sailed from the Port of Los Angeles to Catalina, carrying sulfuric acid and DDT of up to 2% purity. The company was reportedly pumping up manufacturing waste directly and sending it to the Port of Los Angeles. pacific ocean. The practice was legal until 1972, but it has been largely overshadowed by Montrose's other waste disposal practices, including pumping a more dilute acidic slurry containing DDT through the Los Angeles County sewer system and into the ocean off Palos Verdes. , the researchers said.
The site is now an underwater Superfund site, and researchers said they could not yet rule out the possibility that it was the source of deep-sea fish and sediment contamination.
Catalina Dump Site 2 was rediscovered in 2011 by University of California, Santa Barbara researcher David Valentine. The Los Angeles Times published an article in 2020 exposing the dump.
Since then, Aluwihare, SDSU study co-author Eunha Hoh, and other collaborators have launched a series of research efforts. They seek to answer his two main questions:
— Are the chemicals at Dump Site 2 being stirred up and ingested by marine life? and
— Are there any unique chemical fingerprints on what was dumped there compared to what was piped in from Palos Verdes?
Researchers collected 215 deep-sea fish from three common species near Dump Site 2. Chemical analysis showed that the fish contained 10 DDT-related compounds, all of which were also present in sediment samples taken at the same time, the authors wrote.
In this undated photo, barrels believed to contain DDT waste sit at the bottom of the ocean floor off the coast of Los Angeles.
In this undated photo, barrels believed to contain DDT waste sit at the bottom of the ocean floor off the coast of Los Angeles.
The researchers said fish sampled at shallower depths had lower concentrations of contaminants and lacked a pair of DDT-related compounds present in the deepest fish.
“None of these fish species are known to feed on seafloor sediments,” said Anela Choi, a biological oceanographer at Scripps and co-author of the study. “There must be another mechanism of exposure to these contaminants. One possibility is to resuspend the sediment around Dump Site 2, allowing these contaminants to enter deeper water food webs. There is a physical or biological process that allows it to invade.”
These findings lead researchers to believe that chemicals concentrated on the ocean floor are making their way into the broader food chain.
“Regardless of the source, this is evidence that DDT compounds are entering deep-sea food webs,” said Margaret Stack, an environmental chemist at SDSU and lead author of the study. “This is a cause for concern because it's not a huge leap for it to reach marine mammals or humans.”
Ho said it is important to understand how DDT-related chemicals enter the food web.
“More than 50 years after DDT was dumped into deep-sea organisms and marine sediments, we're still seeing this contamination,” she says. “I don't know if the company expected the effects of the contamination to last this long, but they did.”
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