The ocean's ultimate trashcan: Hadal trenches as major depositories for plastic pollution

Guyu Peng1, Richard Garth James Bellerby2, Feng Zhang1, Xuerong Sun3 and Daoji Li1, (1)East China Normal University, State Key Laboratory of Estuarine and Coastal Research, Shanghai, China, (2)State Key Laboratory for Estuarine and Coastal Research, East China Normal University, SKLEC-NIVA Centre for Marine and Coastal Research, Shanghai, China, (3)State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai, China
Abstract:
Plastic debris and marine microplastics are being discharged into the ocean at an alarming scale and have been observed throughout the marine environment. Here we report microplastic in sediments of the Challenger Deep, the deepest known region on the planet, abyssal plains and hadal trenches located in the Pacific Ocean (4900 m to 10890 m). Microplastic abundance reached 71.1 items per kg dry weight sediment. That high concentrations are found at such remote depths, knowing the very slow sinking speed of microplastics, suggests that supporting mechanisms must be at-play. We discuss cascading processes that transport microplastics on their journey from land and oceanic gyres through intermediate waters to the deepest corners of the ocean. We propose that hadal trenches will be the ultimate sink for a significant proportion of the microplastics disposed in the ocean. The build-up of microplastics in hadal trenches could have large consequences for fragile deep-sea ecosystems.