Long-Range Transport of Oil by Marine Plastic Debris: Evidence from an 8500 km Journey

Weathering processes typically restrict the distance spilled oil travels to a few hundred kilometers in the ocean. Leveraging oiled marine debris as "drifters of opportunity", we tested the hypothesis of the unprecedented long-range (thousands of kilometers) transequatorial transport of oil adhered to marine debris by surface currents. Dispersion modeling backed by historical drift bottle experiments supported the plausibility for this hypothesis, and molecular forensics provided the definitive evidence proving it. Oil carried by marine debris arriving at Palm Beach, Florida in 2020 matched oil from the 2019 Brazil mystery oil spill, having traveled ∼8500 km in ∼240 days. We demonstrate an additive contaminant effect whereby plastic pollution facilitates the long-range transport of oil pollution. These findings underscore that regional inputs into the global ocean can have transboundary impacts.