Transition paths of marine debris and the stability of the garbage patches

TL;DR

This study applies transition path theory to satellite-tracked marine debris trajectories to identify pollution pathways and sources, providing insights for targeted ocean cleanup strategies and understanding debris transport dynamics.

Contribution

It introduces an adapted TPT framework for open physical systems and applies it to real satellite data to reveal pollution routes and source regions.

Findings

Identified a major pollution source for the Great Pacific Garbage Patch.

Characterized the Indian Ocean gyre as a weak trap for plastic waste.

Found that gyres tend to export debris to coastlines under strong winds.

Abstract

We used transition path theory (TPT) to infer "reactive" pathways of floating marine debris trajectories. The TPT analysis was applied on a pollution-aware time-homogeneous Markov chain model constructed from trajectories produced by satellite-tracked undrogued buoys from the NOAA Global Drifter Program. The latter involved coping with the openness of the system in physical space, which further required an adaptation of the standard TPT setting. Directly connecting pollution sources along coastlines with garbage patches of varied strengths, the unveiled reactive pollution routes represent alternative targets for ocean cleanup efforts. Among our specific findings we highlight: constraining a highly probable pollution source for the Great Pacific Garbage Patch; characterizing the weakness of the Indian Ocean gyre as a trap for plastic waste; and unveiling a tendency of the subtropical gyres to export garbage toward the coastlines rather than to other gyres in the event of anomalously intense winds.