White Halos on Sunken Barrels Reveal Decades of Alkaline Pollution on LA Seafloor

Off the Los Angeles coast, scientists found submerged barrels from mid-20th‑century dumping leaking caustic alkaline waste, creating white halos formed by brucite and driving highly alkaline conditions (pH around 12) in surrounding sediments. While earlier concerns about DDT were not borne out, the findings point to alkaline byproducts as the likely pollutant, with about one‑third of barrels showing halos and nearby microbes largely suppressed. The exact contents and full environmental impact remain uncertain, but the evidence shows lasting, localized disruption of marine life for decades.