Simulation of seasonal transport of microplastics and influencing factors in the China Seas based on the ROMS model

Rongze Liu; Teng Wang; Junde Li; Xiaohui Liu; Qing Zhu

doi:10.1016/j.watres.2023.120493

Simulation of seasonal transport of microplastics and influencing factors in the China Seas based on the ROMS model

Water Res. 2023 Oct 1:244:120493. doi: 10.1016/j.watres.2023.120493. Epub 2023 Aug 15.

Authors

Rongze Liu¹, Teng Wang², Junde Li¹, Xiaohui Liu³, Qing Zhu⁴

Affiliations

¹ College of Oceanography, Hohai University, Nanjing 210098, China.
² College of Oceanography, Hohai University, Nanjing 210098, China. Electronic address: tengwang@hhu.edu.cn.
³ State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou 310012, China.
⁴ Key Laboratory of Watershed Geographic Sciences, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China.

PMID: 37683497
DOI: 10.1016/j.watres.2023.120493

Abstract

Elucidating the mechanisms governing microplastic transport and spatial distribution in offshore waters is essential to microplastic control. However, current research on microplastic transport in the China Seas is largely restricted to small-scale investigations, which do not provide a comprehensive result. Therefore, in this study, we used the Regional Ocean Modeling System (ROMS) combined with the Lagrangian Transport (LTRANS v.2) model to investigate how microplastics are transported around the China Seas during different seasons and under climatological river discharge. Our findings showed that the microplastic pathways and spatial distributions exhibit marked seasonal variations controlled by circulation patterns in the China Seas, river discharge values, and the characteristics of the microplastic materials. Floating microplastics exhibited the longest transport distance in summer, when microplastics from the Pearl River could be transported up to 1375.8 km through the Tokara and Tsushima straits. The heavy pollution areas in summer were located in the South Yellow Sea and East China Sea, mainly resulting from the contribution of the Yangtze River (>66%). In autumn and winter, more than three-quarters of the microplastics beached off the south-central Chinese coast. In addition, simulating the vertical velocity of the water prolonged the time required for microplastics to reach the open ocean, thereby reducing the amount of microplastics entering the Pacific Ocean by 6% compared to the simulation without the vertical velocity of the water in summer. Microplastics with higher densities were generally transported shorter distances. The transmission distances of PET and PS were two orders of magnitude smaller than that of PE. This study enhances knowledge of the sources and fates of offshore microplastics and provides scientific support for offshore microplastic control.

Keywords: China Seas; Distribution; Marine; Microplastic pollution; Numerical model; Transportation.

MeSH terms

China
Microplastics*
Plastics*
Seasons
Water

Substances

Microplastics
Plastics
Water