Plastic After an Extreme Storm: The Typhoon-Induced Response of Micro- and Mesoplastics in Coastal Waters

Ryota Nakajima,Kazumasa Oguri,Heather Ritchie,Tetsuro Ikuta,Takao Yoshida,Masashi Tsuchiya,Tomo Kitahashi,Takuya Yamauchi,Kunihiro Aoki,Noriyuki Isobe,Yuriko Nagano,Maki Suzukawa,Yosaku Maeda,Toru Miyama,Katsunori Fujikura,Akinori Yabuki,Kiichiro Kawamura

doi:10.3389/fmars.2021.806952

Abstract

Extreme storms, such as tropical cyclones, are responsible for a significant portion of the plastic debris transported from land to sea yet little is known about the storm response of microplastics and other debris in offshore and open waters. To investigate this, we conducted floating plastic surveys in the center of Sagami Bay, Japan approximately 30 km from the coastline, before and after the passage of a typhoon. The concentrations (number of particles/km2) of micro- and mesoplastics were two orders of magnitude higher 1-day after the typhoon than the values recorded pre-typhoon and the mass (g/km2) of plastic particles (sum of micro- and mesoplastics) increased 1,300 times immediately after the storm. However, the remarkably high abundance of micro- and mesoplastics found at 1-day after the typhoon returned to the pre-typhoon levels in just 2 days. Model simulations also suggested that during an extreme storm a significant amount of micro- and mesoplastics can be rapidly swept away from coastal to open waters over a short period of time. To better estimate the annual load of plastics from land to sea it is important to consider the increase in leakages of plastic debris into the ocean associated with extreme storm events.

Highlights

Each year, approximately 20 million metric tons of land-based plastic debris makes its way into aquatic systems, including oceans and freshwater networks, and this figure is only likely to rise (Borrelle et al, 2020)
Our study addressed two key topics regarding typhoon derived debris through observations and model simulations: (1) how much does the concentration of floating plastic debris offshore change before and after a typhoon passage? and (2) where does the debris that is carried from the land to coastal waters by the typhoon go? This will significantly contribute to our understanding of the fate of plastic debris after an extreme storm
At 3-days before the typhoon passed (September 7th), the densities of micro- and mesoplastics were on average (± SD) 101,762 ± 13,213 pieces km−2 and 11,340 ± 7,198 pieces km−2, respectively (Figures 2A,B)

Summary

Introduction

Approximately 20 million metric tons of land-based plastic debris makes its way into aquatic systems, including oceans and freshwater networks, and this figure is only likely to rise (Borrelle et al, 2020). Tropical cyclones, including typhoons and hurricanes, are the most extreme episodic weather events occurring at low- and midlatitudes They bring heavy precipitation resulting in increased river flow and terrestrial runoff (Tsuchiya et al, 2015), and when coupled with the powerful winds they generate tropical cyclones can be a significant event that enhances the loading of plastic debris from land to the marine environment (Pelamatti et al, 2019; Wang et al, 2019; Hitchcock, 2020; Lo et al, 2020; Garcés-Ordóñez et al, 2021). Understanding the leakage patterns of marine plastic debris by tropical cyclones and other storm events is essential for determining strategies to mitigate further pollution, especially in regions where there are frequent typhoon or hurricane events

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Discussion

Conclusion