From surface to bottom: Tracking the temporal and morphological heterogeneity of microplastics in the maximum turbidity zone of the Yangtze Estuary

Tiefeng Cui; Xiaohui Wang; Nian Wei; Xuri Dong; Lixin Zhu; Kai Liu; Daoji Li

doi:10.1016/j.jhazmat.2025.138944

From surface to bottom: Tracking the temporal and morphological heterogeneity of microplastics in the maximum turbidity zone of the Yangtze Estuary

J Hazard Mater. 2025 Jun 15:495:138944. doi: 10.1016/j.jhazmat.2025.138944. Online ahead of print.

Authors

Tiefeng Cui¹, Xiaohui Wang¹, Nian Wei², Xuri Dong³, Lixin Zhu⁴, Kai Liu⁵, Daoji Li⁶

Affiliations

¹ State Key Laboratory of Estuarine and Coastal Research, East China Normal University, 500 Dongchuan Road, Shanghai 200062, China; Region Training and Research Center on Plastic Marine Debris and Microplastics, IOC-UNESCO, 200241, China; Hainan Research Institute of East China Normal University, Sanya 572025, China.
² State Key Laboratory of Estuarine and Coastal Research, East China Normal University, 500 Dongchuan Road, Shanghai 200062, China; Region Training and Research Center on Plastic Marine Debris and Microplastics, IOC-UNESCO, 200241, China; Hainan Research Institute of East China Normal University, Sanya 572025, China; East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, 300 Jungong Road, Shanghai 200090, China.
³ Co-Innovation Center of Jiangsu Marine Bio-industry Technology, Jiangsu Ocean University, Lianyungang 222005, China.
⁴ State Key Laboratory of Estuarine and Coastal Research, East China Normal University, 500 Dongchuan Road, Shanghai 200062, China; Region Training and Research Center on Plastic Marine Debris and Microplastics, IOC-UNESCO, 200241, China; Hainan Research Institute of East China Normal University, Sanya 572025, China. Electronic address: lixinzhu0305@hotmail.com.
⁵ State Key Laboratory of Estuarine and Coastal Research, East China Normal University, 500 Dongchuan Road, Shanghai 200062, China; Region Training and Research Center on Plastic Marine Debris and Microplastics, IOC-UNESCO, 200241, China; Hainan Research Institute of East China Normal University, Sanya 572025, China; School of Geography, Earth & Environmental Sciences, the University of Birmingham, Edgbaston, Birmingham B15 2TT, UK. Electronic address: kailiu1991@hotmail.com.
⁶ State Key Laboratory of Estuarine and Coastal Research, East China Normal University, 500 Dongchuan Road, Shanghai 200062, China; Region Training and Research Center on Plastic Marine Debris and Microplastics, IOC-UNESCO, 200241, China; Hainan Research Institute of East China Normal University, Sanya 572025, China. Electronic address: daojili@sklec.ecnu.edu.cn.

PMID: 40580734
DOI: 10.1016/j.jhazmat.2025.138944

Abstract

The estuary channels the inland to the coastal environment, considered a significant route of marine microplastic (MP) pollution inflow. However, the water column profiles of MPs in this area remain elusive, especially at high temporal resolution scale, hindering our ability to approximate its flux and evaluate the effectiveness of mitigation efforts. Hence, we investigated the physical and chemical diversity of MPs in the water column of the Yangtze River Estuary Maximum Turbidity Zone by a time-series monitoring strategy. Utilizing an advanced Laser Direct Infrared Chemical Imaging System (LDIR) imaging method, we quantified the shift patterns of MPs in this area. Overall, the average abundance of MPs reached 35.62 ± 34.86 items/L and 27.54 ± 31.54 items/L in surface and bottom waters throughout two tide cycles, respectively. MPs smaller than 100 μm were the most prevalent, with polyethylene (PE) and polypropylene (PP) being the dominant types in both layers. Despite moderate shape variability but relatively uniform sizes of surface MPs across polymer types, MPs in bottom estuarine water showed substantial heterogeneity in both size and shape among different polymers. This work underscores the necessity of high temporal resolution monitoring and integrating vertical stratification and multidimensional morphological analyses in MP studies of ecological assessment.

Keywords: Maximum Turbidity Zone; Microplastics; Morphological heterogeneity; Water column; Yangtze Estuary.