Toxic Legacy: Alkaline Waste from Barrels Off Los Angeles Coast

Decades-old barrels of industrial waste dumped off the coast of Los Angeles are leaking caustic alkaline substances into the marine environment, creating extreme conditions on the seafloor. This situation has raised concerns about the long-term ecological impacts of these pollutants, which have persisted since their disposal between the 1930s and early 1970s.

The Hill

From the 1930s to the early 1970s, at least 14 designated dump sites were utilized off Southern California's coast for disposing of various industrial wastes, including radioactive materials, military explosives, and chemical byproducts. The practice was legal at the time, and the barrels were believed to contain the toxic pesticide DDT, which was widely used until its ban in 1972.

Scientists Make Startling Discovery Beneath Los Angeles Ocean Floor That’s Still Haunting the Waters

A study conducted by researchers from the Scripps Institution of Oceanography at the University of California, San Diego, has revealed that the barrels with white halos surrounding them do not contain DDT as previously assumed. Instead, they are leaking highly caustic alkaline waste. The research, published in the journal *PNAS Nexus*, involved sediment samples collected in 2021 near five barrels, three of which exhibited the distinctive halos.

Decades-Old Barrels of Industrial Waste Still Impacting Ocean Floor Off LA

The study's lead author, Johanna Gutleben, noted that the alkaline waste has transformed parts of the seafloor into environments where only specialized bacteria can survive. The halos form when alkaline waste reacts with magnesium in seawater, creating a mineral called brucite, which hardens the sediment and maintains a high pH level.

Live Science

The alkaline conditions created by the leaking waste have resulted in low microbial diversity in the sediment surrounding the barrels. The researchers found that the microbial DNA present was primarily from extremophiles adapted to high pH environments, similar to those found in deep-sea hydrothermal vents. Paul Jensen, a senior author of the study, emphasized the shocking persistence of these effects over 50 years, indicating that the alkaline waste should be considered a persistent pollutant with significant long-term environmental impacts.

Gizmodo

While the study has clarified the nature of the waste, it also highlights the need for further investigation into the specific chemicals contained within the barrels. The researchers acknowledged that without knowing the total number of barrels and their contents, quantifying the environmental impact remains challenging. Jensen expressed concern over the localized effects on microbial communities, suggesting that the situation warrants urgent attention.

Live Science

The findings from this research shift the focus from a singular pollutant, DDT, to a broader array of hazardous materials dumped in the region. Gutleben remarked, “DDT was not the only thing that was dumped in this part of the ocean, and we have only a very fragmented idea of what else was dumped there.” The study underscores the importance of using the white halos as indicators to assess the extent of contamination and to guide future research on the ecological consequences of these long-standing pollutants.

Scientists Make Startling Discovery Beneath Los Angeles Ocean Floor That’s Still Haunting the Waters

• “As Johanna Gutleben, the study’s first author, explained, “One of the main waste streams from DDT production was acid and they didn’t put that into barrels.” — Johanna Gutleben, Postdoctoral Scholar, Scripps Institution of Oceanography

Scientists Make Startling Discovery Beneath Los Angeles Ocean Floor That’s Still Haunting the Waters

• “It's shocking that 50-plus years later you're still seeing these effects.” — Paul Jensen, Emeritus Marine Microbiologist, Scripps Institution of Oceanography

Newsweek