To hunt a killer

By Keely Sexton

The notorious DDT: It was the wonder pesticide of the mid-1900s. It kept soldiers safe from malaria and prevented crops from being besieged with insects. But like many gift horses, this one proved to have a fatal flaw: DDT was ultimately, and perhaps inevitably, linked to environmental devastation, threatening multiple species with extinction. 

It was banned for most uses in the United States in 1972. A Superfund site was established at the chief manufacturing facility to clean up the results of decades of improper disposal of the chemical.

But that's not where the story ended. 

While animal populations rebounded over time, with the cessation of widespread agricultural use and with the clean-up on land, something was happening beyond the reach of the environmentalists, activists and scientists at the time: a deep-sea DDT dump site off the Palos Verdes peninsula of California, where thousands upon thousands of unusable barrels of DDT were barged from the manufacturing site and sunk deep in the ocean. 

Veronika Kivenson FP’13 is one of the researchers working on learning more about the issue. In a front-page story in the Los Angeles Times, Kivenson explained that one of the main concerns is that researchers still don’t know how many barrels are on the ocean floor, under pressure 90 times greater than surface pressure, leaking toxic chemicals — Kivenson and advisor David Valentine of UC Santa Barbara call them “‘toxicles” — in such concentrations that they can be snapped off by remote robots.

“These barrels do seem to be leaking over time,” she told the L.A. Times. “This toxic waste is just kind of bubbling down there, seeping, oozing, I don’t know what word I want to use. ... It’s not a contained environment.”

Shipping records indicate that up to half a million barrels of DDT-laced acid sludge sit on the ocean floor, slowly corroding. What’s more, DDT is such a stable chemical, it persists long after it is introduced. 

The team estimated that each barrel contains about 0.5 to 2 percent technical-grade DDT, meaning that the half million barrels contained a total of about 384 to 1,535 tons of DDT. One spot had a concentration 40 times higher than the highest surface sediment contamination at the Superfund site. 

Kivenson traces the beginning of her research to her time at Mount Holyoke College. 

“It feels like just yesterday that I was nervously starting as a STEM transfer junior at Mount Holyoke,” she said. “I am so deeply grateful for the experience. It made a world of difference for me, and the year that I graduated, 2013, is when I started this project!”