Deepwater Horizon oil spill caused months-long ‘dirty blizzard’

A “dirty blizzard” bombarded the Gulf of Mexico seafloor with pollution from the 2010 Deepwater Horizon oil spill for months after workers sealed the leak, new research shows.

Marine snow, an organic material that floats down from the ocean’s upper layers, carried the pollution to the seafloor, researchers report the week of May 30 in the Proceedings of the National Academy of Sciences.

Monitoring accumulating ocean sediment 7.4 kilometers away from the spill site, the researchers discovered that soot from burning oil slicks continued sinking onto the ocean floor for two months after the fires were extinguished. Other contaminants, such as drilling fluid, precipitated for around five months after the well was sealed, researchers report. In total, the spill dumped an estimated 16,000 to 26,000 metric tons of oil pollution to the deep ocean.

This pollution snowstorm could help explain the spill’s unexpectedly large impact on fish and deep-sea corals, the researchers propose.