Decades-old barrels discovered beneath Los Angeles waters don't contain DDT, but something more dangerous: Study

For decades, some mysterious objects have been hidden off the coast of Los Angeles. These objects, essentially barrels, date back between the 1930s and 1970s. New findings regarding these barrels have now appeared in the journal PNAS NEXUS, challenging multiple past assertions about the barrels, specifically regarding their contents. Before the study, it was believed that these corroded barrels contained the harmful pesticide DDT (Dichlorodiphenyltrichloroethane). However, after monitoring these objects for decades, researchers noted some things around the barrels, making them question whether DDT was the only thing inside these barrels. 

Strange Halo Around the Barrels

These metal barrels, after years submerged underwater, have become corroded, according to Daily Galaxy. Researchers feared the harm it might be imparting to the ocean, as they suspected it contained DDT. DDT is a toxic pesticide widely used in the USA until it was banned in 1972. For years, experts believed that the white halos appearing in the sediment around barrels were a consequence of DDT-associated chemicals coming out. However, a new investigation points to another direction, which, if true, increases the danger that these barrels pose to the marine ecosystem. 

Reality of the Halo

The barrels entered the people's consciousness again in 2020 when their photographs became public, according to Phys.org. No one knows how many of these barrels are in the waters. Researchers speculated these barrels were dumped in the ocean, with the intention of removing waste. Along with barrels, the white halo also grabbed people's attention. Researchers were intrigued, as the halos appeared only around certain barrels, and not all. After further investigation, they concluded that the halos were surrounding containers with caustic alkaline waste.

However, experts couldn't determine which chemicals were present in the barrels; they looked into records and found that DDT manufacturing itself produced both alkaline and acidic waste. Hence, it was a possibility that instead of DDT, one of its byproducts was locked into some of the barrels. "One of the main waste streams from DDT production was acid and they didn't put that into barrels," said Johanna Gutleben, a Scripps postdoctoral scholar and the study's first author. "It makes you wonder: What was worse than DDT acid waste to deserve being put into barrels?" Experts also found that alkaline waste was generated from other industries, like oil manufacturing, in the 90s. So, those wastes could have also found a way into the barrels. 

The team used the remotely operated vehicle (ROV) SuBastian to gather sediment samples from a specific distance from five barrels. Amongst these five barrels, three had halos. Beneath the halos, the sea floor was uncharacteristically concrete. A closer look revealed that the solid crust was mostly composed of a mineral named brucite. Researchers believe that the alkaline waste leaked from the containers, reacted with the surrounding magnesium, and formed brucite.

Effect of the Waste

Upon further analysis of sediment samples and the hardened piece of halo barrel crust from the three particular barrels, scientists found that the DDT contamination did not increase near the barrels, which was what made them speculate that there was something else in these containers. The team was unable to extract any microbial DNA from the hardened halo sample, and also noted that pH was extremely high—around 12. It means: highly alkaline. Similar readings came back for samples near other barrels with a halo. The alkaline nature could be the reason why there was so little microbial DNA in the samples around the halo barrels. The environment does not support microbial diversity, and the bacteria that do end up living in such areas are specifically adapted to alkaline environments, like alkaline hot springs and deep-sea hydrothermal vents.

Researchers claim that the brucite is slowly but steadily dissolving. The dissolution is making it harder for extremophilic microbes to survive in the alkaline environment. The halos could be deposits of calcium carbonate, which forms when the water's pH increases due to processes like brucite dissolution. "This adds to our understanding of the consequences of the dumping of these barrels," said Paul Jensen, emeritus marine microbiologist at Scripps and senior author of the study. "It's shocking that 50-plus years later, you're still seeing these effects. We can't quantify the environmental impact without knowing how many of these barrels with white halos are out there, but it's clearly having a localized impact on microbes."

The study has noted several long-term impacts of this caustic alkaline waste. One of them is the transformation of some seafloor into extreme environments, like natural hydrothermal vents, where most lifeforms cannot survive. Currently, experts are suggesting an accurate survey of the number of barrels present in the waters. Therafter, they want to separate the barrels with a white halo to understand the extent of alkaline waste contamination in this marine environment. Accurate monitoring of this waste would be the first step to protecting the ocean from it.