Sloppy Disposal – A Combination of Targeted and Non-Targeted GCxGC-HRT Investigations of DDT Manufacturing Waste Products

The autonomous underwater vehicle (AUV) Sentry, and the remotely operated vehicle (ROV) Jason, mapped, explored, and sampled an abandoned deep-sea industrial waste dump site located in the Southern California Bight known as the Palos Verdes Mass-transport Dumpsite (MTD) in the vicinity of Los Angeles, CA. Documentation in a technical report by Chartrand et al., states this area may contain between 336,000−504,000 barrels of acid sludge waste from the production of persistent organic pesticides (POPs)—more specifically, DDT waste—in addition to various other waste streams. Montrose Chemical Corporation (MCC) was the largest global supplier of DDT, manufacturing ∼800,000 tons at their Los Angeles County plant from 1947 to 1982. Offshore disposal of manufacturing byproducts resulted in at-sea dumping of an estimated 2,000−3,000 barrels/month (∼1 million gallons of waste per year) between 1947 and 1961. Ocean dumping practices were authorized by the California Department of Fish and Game, the US Coast Guard, and the Los Angeles Harbor Department, specifying waste hauling companies dump containerized waste at designated locations in the basins off Southern California, ∼16 km offshore. However, short-dumping closer to shore was common practice. Discarded waste containers litter this region of the sea-floor and the leaked contents of these containers are abundant in the suboxic benthic environment around these sites, thus providing a POP entry point into the marine food web. Following retrieval ROV Jason, sediment cores were processed, stored, and subsequently analyzed at the Woods Hole Oceanographic Institution. A follow-on science cruise collected more sediment core samples via gravity coring along a transect through the Southern California Bight.

In this presentation, we describe the importance of both targeted and non-targeted sediment core analysis from the Palos Verdes MTD for POPs and other non-targeted compounds by comprehensive two-dimensional gas chromatography coupled with high resolution time-of-flight mass spectrometry.