Scripps researchers uncover what lies inside mysterious haloed barrels on the seafloor – San Diego Union-Tribune

When researchers found a number of eroding barrels on the seafloor off the coast of Southern California with an eerie, white halo encircling them, it wasn’t instantly clear what they held.

The barrels signify just some of the 1000’s of barrels and barrel-sized objects that litter the seafloor within the San Pedro Basin, a stretch of ocean between Long Beach and Santa Catalina Island.

The space is considerably polluted with DDT, a chemical used as an insecticide that was banned in 1972. While researchers thought these haloed barrels might have carried DDT waste, they didn’t know for positive.

Until now. New research published Tuesday from UC San Diego’s Scripps Institution of Oceanography discovered that the barrels with halos comprise caustic alkaline waste — a extremely corrosive materials that has been leaking out of the barrels for many years.

The leaked substance, which can take 1000’s of years to interrupt down, has created an excessive setting surrounding the barrels the place little to no life can survive — just like deep sea hydrothermal vents, however not naturally discovered off the California coast.

“There shouldn’t be these extreme habitats out there in that part of the ocean, and that’s affecting not only the microbes, but the animals and all the way up the food chain, and who knows what else,” mentioned Paul Jensen, retired marine microbiologist at Scripps and senior writer of the research.

The work is an element of a bigger mission with researchers throughout the area to evaluate the San Pedro Basin websites, the place many years of dumping chemical substances like DDT and different pollution have raised environmental and human well being dangers.

The analysis has led to a variety of discoveries. A number of years in the past, Scripps researchers discovered that a lot of the 1000’s of barrel-sized objects on the seafloor have been discarded World War II-era munitions and pyrotechnics.

While the researchers didn’t establish the precise chemical substances current within the barrels, alkaline waste was produced in DDT manufacturing, in addition to oil refining — each outstanding industries within the area within the mid-Twentieth century.

“We only find what we are looking for, and up to this point we have mostly been looking for DDT,” Johanna Gutleben, a Scripps postdoctoral scholar and the research’s first writer, mentioned in a press release. “Nobody was thinking about alkaline waste before this, and we may have to start looking for other things as well.”

The presence of DDT in California and off its coast has had a long-lasting environmental influence: Significant quantities have been present in endangered California condors, and the chemical has been linked to most cancers in sea lions.

But the newly-discovered alkaline waste, seeping from barrels 3,000 toes deep, might doubtlessly have an effect on the ocean much more than DDT. According to the research, it might take a number of thousand years for the consequences of the fabric to resolve.

“We’ve discovered a new persistent pollutant in the bottom of the ocean that’s going to outlast the negative effects of DDT,” Jensen mentioned. “That was so eye-opening for us.”

Jensen and Gutleben made their discovery accidentally.

In 2021, the researchers and their staff have been on a analysis vessel off the California coast to check mineral-rich habitats for one more mission. But they have been close to the San Pedro Basin websites, in order that they determined to take a detour to gather some samples.

They centered on 5 barrels within the dumpsites, three of which had white halos round them — nevertheless it wasn’t simple to gather samples. The seafloor inside the rings across the barrels had hardened like concrete, stopping them from amassing samples with a coring system that might be inserted into the seafloor.

They ended up breaking off a bit of the sediment with the robotic arm of a remotely-operated automobile, then bringing it as much as the floor to check it for DDT ranges, microbial content material and minerals.

The hardened sediment largely contained the mineral brucite — created via alkaline waste interacting with magnesium within the ocean water that resulted within the crust-like floor surrounding the barrels. When the excessive pH ranges within the sediment work together with the water, it types a chemical compound referred to as calcium carbonate that deposits as a white mud, forming the halos.

Jensen says he would have anticipated the alkaline waste to dissipate within the ocean water quickly after it was dumped. But by reaching the seafloor and interacting with the sediment — mainly turning it to rock — the alkaline waste will now slowly dissolve.

Gutleben pressured that questions nonetheless loom over the widespread results of the alkaline waste, in addition to what mixture of chemical substances lie inside the barrels that led them to be dumped into the ocean within the first place.

“We currently don’t know how many of those barrels are down there precisely,” she mentioned. “We don’t know how many of them contain this alkaline waste, so we don’t know how big the problem really is.”

Originally Published: September 11, 2025 at 9:06 AM PDT