Global simulations of marine plastic transport show plastic trapping in coastal zones

Victor Onink,Charlotte Laufkötter,Matthew J Hoffman,Cleo E Jongedijk,Erik Van Sebille

doi:10.1088/1748-9326/abecbd

Abstract

Global coastlines potentially contain significant amounts of plastic debris, with harmful implications for marine and coastal ecosystems, fisheries and tourism. However, the global amount, distribution and origin of plastic debris on beaches and in coastal waters is currently unknown. Here we analyze beaching and resuspension scenarios using a Lagrangian particle transport model. Throughout the first 5 years after entering the ocean, the model indicates that at least 77% of positively buoyant marine plastic debris (PBMPD) released from land-based sources is either beached or floating in coastal waters, assuming no further plastic removal from beaches or the ocean surface. The highest concentrations of beached PBMPD are found in Southeast Asia, caused by high plastic inputs from land and limited offshore transport, although the absolute concentrations are generally overestimates compared to field measurements. The modeled distribution on a global scale is only weakly influenced by local variations in resuspension rates due to coastal geomorphology. Furthermore, there are striking differences regarding the origin of the beached plastic debris. In some exclusive economic zones (EEZ), such as the Indonesian Archipelago, plastic originates almost entirely from within the EEZ while in other EEZs, particularly remote islands, almost all beached plastic debris arrives from remote sources. Our results highlight coastlines and coastal waters as important reservoirs of marine plastic debris and limited transport of PBMPD between the coastal zone and the open ocean.

Highlights

Marine plastic debris is found in almost all marine habitats, on coastlines worldwide [1]
Coastal ecosystems can be sensitive to plastic pollution [2], and plastic debris on beaches can reduce the economic value of a beach by up to 97% [3]
With the Jambeck input, and assuming 54% of the input is buoyant, this corresponds to 0.72–2.06 × 106 tons of beached positively buoyant marine plastic debris (PBMPD) originating from plastic debris released in 2010 alone

Summary

Introduction

Marine plastic debris is found in almost all marine habitats, on coastlines worldwide [1]. While an estimated 1.15–12.7 million tons of plastic enter the ocean per year [4,5,6], the amount of positively buoyant marine plastic debris (PBMPD) found floating at the ocean surface is estimated to be significantly lower [7,8,9,10]. Given the scarcity of measurements relative to the length of coastlines, limited insight into local temporal and spatial fluctuations in beached PBMPD concentrations and the lack of a standardized sampling methodology, it is currently not possible to estimate the total amount of beached plastic debris from field measurements alone, or to describe the global pattern of beached plastic [1]

Methods

Results

Discussion

Conclusion