For decades, thousands of tons of chemical barrels lay undisturbed on the Los Angeles coast, a legacy of irresponsible waste disposal from the 1930s to the 1970s. Initially, the focus was on DDT, a known carcinogen. However, the discovery of unusual 'ghostly halos' surrounding these barrels pointed towards a far more complex and alarming truth.
A team from the Schmidt Ocean Institute, utilizing the remotely operated vehicle (ROV) SuBastian, embarked on a mission to unravel this mystery. Their attempts to collect samples were hampered by the concrete-like texture of the seabed surrounding the barrels, a clear indication of significant environmental alteration.
Analysis of the collected sediment revealed a surprising finding: DDT levels did not correlate with proximity to the barrels. This crucial observation debunked the long-held assumption that DDT was the sole culprit behind the contamination. Instead, microbial DNA analysis revealed a low diversity of extremophile bacteria – microorganisms typically found in extreme environments like hydrothermal vents.
Further testing revealed an extraordinarily high pH level of approximately 12, indicating highly caustic alkaline waste. This discovery completely shifted the understanding of the environmental damage. As Johanna Gutleben, lead author of the study, stated, "One of the main waste streams from DDT production was acid; they didn’t put that into barrels. It makes you wonder: What was worse than DDT acid waste to deserve being put into barrels?"
The 'ghostly halos' themselves are a product of a chemical reaction between the alkaline waste and seawater, resulting in the formation of brucite, the mineral responsible for the hardened sediment and alkaline conditions. This, in turn, interacts with seawater to create calcium carbonate deposits.
This revelation significantly alters our comprehension of the decades-long environmental disaster. While the exact contents of the barrels remain unknown, the focus has shifted towards identifying the source of this highly alkaline waste. The study highlights the limited scope of previous investigations, predominantly focused on DDT. As Gutleben emphasized, "DDT was not the only thing that was dumped... We only find what we are looking for, and up to this point, we have mostly been looking for DDT."
This discovery elevates alkaline waste to a level of environmental concern comparable to DDT, challenging the initial assumption that seawater would quickly dilute such substances. Paul Jensen, a senior author of the study, noted the enduring effects, stating, "It’s shocking that 50-plus years later you’re still seeing these effects." The study, published in PNAS Nexus, urges further investigation into the extent and impact of this previously overlooked form of marine pollution.
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Originally published at: https://www.iflscience.com/strange-halos-have-formed-around-barrels-of-chemicals-dumped-off-las-coast-over-50-years-ago-80743
