Occurrence of Microplastic Pollution in the Beibu Gulf, the Northern South China Sea

Zuhao Zhu,Huihua Wei,Wei Huang,Yao Guan,Qiufeng Zhang,Xingxu Wu

doi:10.3389/fmars.2021.821008

Abstract

In this study, microplastics were sampled and analyzed from surface water and sediment samples from July to August in 2020, in the Beibu Gulf (the northern South China Sea [SCS]), a gulf with intensive fishery activities while the economy is less developed, compared with other coastal areas of China. The abundances of microplastics in seawater and sediment in the Beibu Gulf were 0.67 items/m3 and 4.33 items/kg of dry weight, respectively. In seawater, the fragments (92.38%) contributed the most, and polystyrene (PS) was the dominant polymer (53.23%). In sediment, the most abundant microplastics were fiber (82.93%) and rayon (RY; 39.54%). The abundances of remarkably higher microplastics were found in the seawater and sediment adjacent to the urban area. The abundances of microplastics in far coastal sediment were only slightly lower than that in the coastal sediment, indicating that microplastics are ready to transport and bury in open area sediment. Significant positive correlations between the microplastic abundance and population density and per capita gross domestic product (GDP) were found in Chinese coastal seawater, with low population density and less developed economy, and the microplastic pollution in the Beibu Gulf was at a low level. This study provides preliminary data of microplastics in the Beibu Gulf, supporting further investigation of transportation fate and management of this emerging pollutant from the coastal zone to the SCS.

Highlights

As an emerging marine pollutant, microplastics can be derived from the degradation of larger plastics in the ocean by sunlight, microbes and mechanical abrasion (Cózar et al, 2014; Khan, 2020; Cordova et al, 2021), or from discharge of wastewater that contains microplastics (Jambeck et al, 2015; Liu et al, 2017; Rochman, 2018; Naji et al, 2020; Nurhasanah et al, 2021)
Seawater The distribution of microplastics in seawater demonstrated the significant contributions of anthropogenic activities to the coastal seawater, especially the strong influence of fishery activities, such as oyster farming and fish culture occurred in the coastal area of the Beibu Gulf (Xue et al, 2020)
One of the reasons was that Tieshan Bay is surrounded by rural area with a population density of 418 persons/km2, presented the remarkably low microplastic abundance (0.39 ± 0.44 items/m3), while Lianzhou Bay is surrounded by urban area with a population density of 4,272 persons/km2, presented the highest microplastic abundance (2.49 ± 1.6 items/m3)

Summary

Introduction

As an emerging marine pollutant, microplastics (defined as those plastics with size < 5 mm) can be derived from the degradation of larger plastics in the ocean by sunlight, microbes and mechanical abrasion (Cózar et al, 2014; Khan, 2020; Cordova et al, 2021), or from discharge of wastewater that contains microplastics (Jambeck et al, 2015; Liu et al, 2017; Rochman, 2018; Naji et al, 2020; Nurhasanah et al, 2021). Due to the low density and stable properties, microplastics can be transported to a long distance in the ocean. Microplastics will produce harmful additives and monomers and carry heavy metals and persistent organic pollutants in the marine environment (Boyle et al, 2020; Catarino et al, 2021; Chen et al, 2021). Microplastics may be ingested by marine organisms, which could cause various adverse effects. They are potentially incorporated into the marine food web through trophic transfer and endanger human health through the consumption of contaminated seafood (Lusher et al, 2017; Pannetier et al, 2020; Philipp et al, 2021). Monitoring microplastics in the ocean (especially the coastal zone) and exploring its biogeochemical cycle are the hot science topics in recent years (Everaert et al, 2018; Li Y. et al, 2020)

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