Oil spills enhanced dispersion and transport of microplastics in sea water and sand at coastal beachheads

Xiangyang Gui; Zhefan Ren; Xiaoyun Xu; Xiang Chen; Ling Zhao; Hao Qiu; Xinde Cao

doi:10.1016/j.jhazmat.2022.129312

Oil spills enhanced dispersion and transport of microplastics in sea water and sand at coastal beachheads

J Hazard Mater. 2022 Aug 15:436:129312. doi: 10.1016/j.jhazmat.2022.129312. Epub 2022 Jun 7.

Authors

Xiangyang Gui¹, Zhefan Ren¹, Xiaoyun Xu¹, Xiang Chen¹, Ling Zhao², Hao Qiu¹, Xinde Cao³

Affiliations

¹ School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
² School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China; National Field Observation and Research Station of Erhai Lake Ecosystem, Yunnan 671000, China.
³ School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China; National Field Observation and Research Station of Erhai Lake Ecosystem, Yunnan 671000, China; Shanghai Engineering Research Center of Solid Waste Treatment and Resource Recovery, Shanghai Jiao Tong University, Shanghai 200240, China. Electronic address: xdcao@sjtu.edu.cn.

PMID: 35739804
DOI: 10.1016/j.jhazmat.2022.129312

Abstract

The coastal zone is being under the threat by accumulation of microplastics (MPs), with much of MPs ending up on the beachhead. Oil spills, which frequently happen in coastal zones due to oil pipe leakage or oil drilling, may affect the behavior of MPs in the beachheads. Herein, sea water and sea sand were collected from three different coastal beachheads including Bohai Sea (BS), East Sea (ES), and South Sea (SS), China, to investigate how the oil spills affect the dispersion and transport of MPs in sea water and sand. The oil spills greatly enhanced the dispersion of MPs in all three sea waters by forming MPs-oil-dispersant agglomerates, which increased the electrostatic repulsion and steric hindrance between MPs particles. Accordingly, the aggregation rates of MPs were reduced from 1.7-8.86 nm min^-1 to 0.39-1.29 nm min^-1. The lowest salinity and highest dissolved organic carbon content in SS sea water favored the highest dispersion of MPs, compared to BS and ES sea water. The improved dispersion of MPs with oil spills enhanced their transport in sea sand with an increase of effluent rates from 0-18.8 % to 5.78-42.2 % for BS and from 30.5-45.2 % to 35.0-60.0 % for SS one. However, the transport of MPs in ES sea sand was lower than 3.62 %, even with oil spills, which was attributed to the strong adsorption of MPs by the rich Fe/Al oxides in ES sea sand through electric attraction. Modeling also showed that oil spills increased the migration rate of 10 mg g^-1 MPs accumulated in the surface 0-1 cm sea sand from 6.50-13.8 cm year^-1 to 8.17-16.7 cm year^-1 after 1500 mm rainfall for 3 years, and the strongest transport of MPs was observed in SS sea sand, with the highest cumulative flux and the longest maximum migration depth as 0.089-0.120 mg/cm² and 50 cm, respectively. These results indicated that the dispersion and transport of MPs can be enhanced by oil spills, but regulated by sea water salinity for MPs dispersion and sea sand Fe/Al oxides for MPs transport, which advanced our understanding of the transport and transformation of MPs in coastal zones.

Keywords: Beachhead; Dispersion; Microplastics; Oil spills; Transport.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Environmental Monitoring
Microplastics
Oxides
Petroleum Pollution* / analysis
Plastics
Sand
Seawater
Water Pollutants, Chemical* / analysis

Substances

Microplastics
Oxides
Plastics
Sand
Water Pollutants, Chemical