Occurrence, Degradation Pathways, and Potential Synergistic Degradation Mechanism of Microplastics in Surface Water: A Review

Purpose of Review

As the initial acceptor of terrigenous microplastics and the primary transporter of marine microplastics, the migration and degradation characteristics of microplastics in surface water need to be better understood. This review aims to summarize the migration and accumulation rules of microplastics in different types of surface water; analyze typical microplastic degradation pathways, and discuss the potential synergistic degradation mechanisms of microplastics in surface water.

Recent Findings

Microplastics was detected in almost all of the surface water. Some significant accumulation of microplastics occurred in local reaches of rivers, lakes, and reservoirs, which was influenced by different environment factors. Though petroleum-based plastics were defined as non-degradable plastics, physical, chemical, and biological degradation pathways of microplastics were constantly verified to occur widely in surface waters. More and more microplastics-degrading microbes, including bacteria, fungi, and even virus, were identified or speculated to directly or indirectly take part in the biodegradation of microplastics. Synergistic degradation processes of microplastics were continuously found in some natural waters, and the mechanisms were explored.

Summary

Multiple sinks of microplastics occurred in the sediments of surface water, such as urban rivers, the mouth of the lake, and reservoirs. The diversity of microplastics-degrading microbes may be much more than what we know previously. This review highlights that there are two scales of synergistic degradation of microplastics, which couple different microbes in the plastispheres and couple biophysical chemical actions in surface water separately. In all, the true degradation potential of microplastics needs to be deeply explored in surface water.

Graphical Abstract

Title: Migration, distribution, and synergistic degradation of microplastics in surface water.

Description: After entering the surface water, microplastics produced by human activities accumulate in different areas through longitudinal, lateral, and vertical migration. At the same time, the synergistic degradation of physical, chemical, and biological microplastics is also taking place, which affects the occurrence of microplastics.