Research Progress on Distribution Characteristics and Formation Mechanisms of Microplastics in the Environment

Abstract

The extensive application of plastic products leads to the increasingly significant harm of plastic wastes to the ecological environment, which is also a focus of global environmental issues. Due to the lack of a sound plastic waste management system, most plastic waste is still treated by the traditional mode or remains in the environment, with low recycling efficiency, and the plastic life cycle has not yet formed. Plastics in the environment will age and degrade under the actions of physical (wear, waves), chemical (ultraviolet radiation, hydrolysis), and biological (fungi, bacteria) factors for a long time and generate micro (nano) plastics. Due to their small particle size, large specific surface area, and charged characteristics, in addition to their own toxicity, they can also be used as carriers or covert carriers of pollutants (heavy metals, persistent organic pollutants, polycyclic aromatic hydrocarbons, bacteria, etc.) to migrate in the environment through runoff, sewage discharge, and hydrometeorology, causing ecological environmental pollution. MPs pollution has been listed as the second largest scientific problem in the field of environmental and ecological science by the United Nations Environment Programme. MPs are widely distributed, and there are different degrees of MPs pollution in the global water (freshwater, ocean), soil, and atmospheric environment. Traces of MPs have also been found in human placentas, human breastmilk, living lungs, and blood in recent years. Therefore, the formation mechanisms of MPs under the actions of physics, chemistry, and microorganisms, as well as their abundance levels and migration characteristics in water, soil, and atmosphere environment were comprehensively reviewed, with the hope of providing reference for monitoring the pollution levels of MPs in the environment, exploring their transport laws in the environment, proposing the management strategy of MPs pollution, and revealing the degradation mechanisms of MPs under different effects.