Whispers Beneath the Waves: 27,000 Sunken Barrels, a Half‑Million Dumped, and a Toxic Secret Rising from the Deep
Off the California coast near Catalina, a quiet mystery sits on the seafloor. White halos circle sunken barrels of chemical waste—a strange, stubborn warning from a long‑gone era. A recent sonar survey found around 27,000 barrels scattered across the San Pedro basin, a fraction of the estimated half‑million dumped by the DDT era, notably by the Montrose Chemical Company. Researchers are watching these halos as potential keys to what the barrels contain and what their long shadow means for marine life decades after the dumping.
A Drowned Archive: The Dumping of DDT‑Era Barrels and the EPA's Deductions
Thousands of containers with unknown contents were dumped into the Pacific off Los Angeles in the 20th century. Over the past decade, remotely operated underwater robots have repeatedly encountered their corroding remains. A 2021 EPA report describes how acid waste containing DDT was moved through a complex chain—from large above‑ground storage tanks, transported by tanker trucks to the Port of Los Angeles, pumped onto Cal Salvage barges, towed to Disposal Site #2, and dumped into the ocean. Tests have repeatedly shown the noxious insecticide persists in the seafloor in this area, but the barrels themselves have been ruled out as the source of the current DDT signal.
The Halo Clue: Alkaline Brucite Rings and a Fragmented Waste Record
Three halo‑ringed barrels were sampled, and the surrounding sediment proved extraordinarily alkaline, with a pH so high that only microbes from hydrothermal vents and alkaline hot springs survive there. The solid material around the barrels is dominated by brucite. As brucite dissolves, it reacts with the seawater’s magnesium, forming a concrete‑like matrix and elevating the pH. This chemical dance leaves ghostly halos of calcium carbonate in its wake. Johanna Gutleben and colleagues note that DDT was not the only thing dumped in this part of the ocean, and we have only a fragmentary idea of what else was discarded. One key line of evidence comes from a quote: “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, published in PNAS Nexus, underscores a localized, long‑term impact on microbes and the difficulty of quantifying the broader environmental cost without knowing how many such halos exist.
