Accumulation of microplastics in a downstream area of a semi-enclosed bay: Implications of input from coastal currents

Kai Liu; Zhiwei Zhang; Hui Wu; Jiaxuan Wang; Rui Wang; Tao Zhang; Zhihua Feng; Daoji Li

doi:10.1016/j.scitotenv.2021.148280

Accumulation of microplastics in a downstream area of a semi-enclosed bay: Implications of input from coastal currents

Sci Total Environ. 2021 Oct 15:791:148280. doi: 10.1016/j.scitotenv.2021.148280. Epub 2021 Jun 5.

Authors

Kai Liu¹, Zhiwei Zhang², Hui Wu², Jiaxuan Wang³, Rui Wang³, Tao Zhang³, Zhihua Feng⁴, Daoji Li⁵

Affiliations

¹ State Key Laboratory of Estuarine and Coastal Research, East China Normal University, 500 Dongchuan Road, Shanghai 200241, China; Plastic Marine Debris Research Center, East China Normal University, 500 Dongchuan Road, Shanghai 200241, China; Regional Training and Research Center on Plastic Marine Debris and Microplastics, IOC-UNESCO, 500 Dongchuan Road, Shanghai 200241, China.
² State Key Laboratory of Estuarine and Coastal Research, East China Normal University, 500 Dongchuan Road, Shanghai 200241, China.
³ Jiangsu Key Laboratory of Marine Bioresources and Environment, Jiangsu Ocean University, 59 Cangwu Road, Lianyungang 222005, China.
⁴ Jiangsu Key Laboratory of Marine Bioresources and Environment, Jiangsu Ocean University, 59 Cangwu Road, Lianyungang 222005, China; Co-Innovation Center of Jiangsu Marine Bio-industry Technology, Jiangsu Ocean University, 59 Cangwu Road, Lianyungang 222005, China; Jiangsu Key Laboratory of Marine Biotechnology, Jiangsu Ocean University, 59 Cangwu Road, Lianyungang 222005, China. Electronic address: fengzhihua@jou.edu.cn.
⁵ State Key Laboratory of Estuarine and Coastal Research, East China Normal University, 500 Dongchuan Road, Shanghai 200241, China; Plastic Marine Debris Research Center, East China Normal University, 500 Dongchuan Road, Shanghai 200241, China; Regional Training and Research Center on Plastic Marine Debris and Microplastics, IOC-UNESCO, 500 Dongchuan Road, Shanghai 200241, China. Electronic address: daojili@sklec.ecnu.edu.cn.

PMID: 34119789
DOI: 10.1016/j.scitotenv.2021.148280

Abstract

Coastal beaches are a vital transitional zone in which terrestrial microplastics (MPs) enter the oceans. However, little is known about the impact of coastal currents on the dispersion and accumulation of MPs, especially in semi-enclosed bays. To address this knowledge gap, we investigated the spatiotemporal variation of MPs in the coastal sediments of Haizhou Bay. The abundance of MPs ranged from 10.94 n/kg to 1309.02 n/kg. Overall, a higher amount of MPs was found in intertidal sediment than in the supratidal zone. Significant seasonal variation was observed only in the intertidal areas of Haizhou Bay, suggesting that hydrodynamics plays a critical role shaping MP abundance. Statistical analyses revealed a roughly exponential increase of MP abundance with distance from the coast, and that a relatively higher abundance of MPs would be found at offshore sites in downstream areas. These results suggest that coastal currents are important contributors of MPs. A numerical model of vertical profiles estimated the total inventory of MPs in coastal areas to be 13.83-580 trillion pieces. Our results suggest a neglected sink of MPs in the sedimentary environments of coastal regions. As a result, the amount of MPs in coastal regions in previous studies could have been underestimated.

Keywords: Beach sediment; Coastal current; Haizhou Bay; Microplastics; Transport.

MeSH terms

Bays
Environmental Monitoring
Geologic Sediments
Microplastics*
Plastics
Water Pollutants, Chemical* / analysis

Substances

Microplastics
Plastics
Water Pollutants, Chemical