Ocean Dumping of Containerized DDT Waste Was a Sloppy Process

Abstract

Industrial-scale dumping of organic waste to the deep ocean was once common practice, leaving a legacy of chemical pollution for which a paucity of information exists. Using a nested approach with autonomous and remotely operated underwater vehicles, a dumpsite offshore California was surveyed and sampled. Discarded waste containers littered the site and structured the suboxic benthic environment. Dichlorodiphenyltrichloroethane (DDT) was reportedly dumped in the area, and sediment analysis revealed substantial variability in concentrations of p,p-DDT and its analogs, with a peak concentration of 257 μg g–1, ∼40 times greater than the highest level of surface sediment contamination at the nearby DDT Superfund site. The occurrence of a conspicuous hydrocarbon mixture suggests that multiple petroleum distillates, potentially used in DDT manufacture, contributed to the waste stream. Application of a two end-member mixing model with DDTs and polychlorinated biphenyls enabled source differentiation between shelf discharge versus containerized waste. Ocean dumping was found to be the major source of DDT to more than 3000 km2 of the region’s deep seafloor. These results reveal that ocean dumping of containerized DDT waste was inherently sloppy, with the contents readily breaching containment and leading to regional scale contamination of the deep benthos.

An ecological basis for dual genetic code expansion in marine deltaproteobacteria

“…Photo-surveys using an autonomous underwater vehicle revealed approximately sixty of an estimated half a million barrels dumped in the San Pedro Basin, off the coast of California ( Fig. S1 ), as described in our previous study (Kivenson et al, 2019). A subset of the barrels exhibited a ring-form microbial mat that commonly, but not exclusively, encircled the barrels.…”

“…2A ). These anaerobic aromatic degradation and dehalogenation abilities may be beneficial for this organism in the environment, given the nature of anthropogenic waste (e.g., chlorinated aromatic hydrocarbon compounds) present at this study site (Kivenson et al, 2019).…”

“…In this study, we capitalize on our recent discovery of a deep ocean industrial waste dump (Kivenson et al, 2019) to investigate the perturbed sediment microbiome and examine genetic code expansion which may enable ecological success associated with this disturbance. In the dominant Deltaproteobacteria, we find extensive evidence of a largely unexplored mechanism for TMA and one-carbon metabolism augmented by dual genetic code expansion.…”

Human Health and Ocean Pollution

“…Direct dumping of industrial wastes into the sea is another source of pollution by toxic chemicals. For example, an estimated 336,000-504,000 barrels of acid sludge waste generated in the production of DDT have been dumped into the Southern California Bight [206]. The disposal process was sloppy and the contents of the barrels readily leaked leading to localized contamination.…”

“…Once they are in the seas, chemical wastes can be further mobilized through natural or human-caused disturbances. For example, PCBs [207] in the Southern California Bight [206] have been mobilized by dredging of contaminated sediments from San Diego Bay.…”