Deep Ocean Disposal in Southern California: DDT

The pesticide DDT was manufactured between 1947 and 1982 in Torrance, CA. Concentrated sulfuric acid wastes resulting from the manufacturing process were disposed of between 1947 and 1961 in San Pedro Basin, a deep ocean basin between Los Angeles and Catalina Island. Originally thought to involve barrels observed at the seafloor, the DDT story has evolved into a story of bulk dumping of DDT-laden acid wastes into the surface ocean that resulted in acute contamination over a geographically large area of the seafloor. Our current research aims to characterize the extent and distribution of DDT and its related breakdown products across the Southern California Bight focused on San Pedro Basin and nearby deep ocean sediments. DDT, a hydrophobic and chemically stable compound, has persisted since its disposal in the mid 1900s. Its chemical and microbially-mediated breakdown is relatively slow but has resulted in the accumulation of DDT breakdown products in the sediments in which DDT lies. We are interested in characterizing the abundance and distribution of the full suite of DDT and related breakdown products (DDT+) in these sediments. Much waste was deposited into the greater San Pedro Basin area and beyond during the 1900s which delivered not only DDT but barrels with unknown contents and more. We have hypothesized some barrels may contain low-level radioactive wastes from the same era, though this work is ongoing.