Considering microplastic characteristics in ecological risk assessment: A case study for China

Microplastics (MPs) pose a significant global concern, requiring a multifaceted approach to their risk assessment procedures, especially concerning their characteristics in the environment. The Horqin Left Middle Banner in Northeast China was chosen for the research region to investigate the abundance, composition, distribution, and ecological impact of MPs in surface agricultural soils. The concentrations of MPs ranged from 300 to 12800 items/kg, with a median concentration of 1550 items/kg (average = 1994 items/kg). The normal-sized MPs (500-5000 µm) had a higher relative abundance than small MPs (<500 µm). MPs were mainly derived from textiles and packaging and were affected by atmospheric transportation. Rayon and PET fibers were the main polymers identified. Furthermore, the potential environmental risks posed by the fundamental characteristics (abundance, chemical composition, and size) of MPs were quantified using multiple risk assessment models. The conditional fragmentation model indicated a propensity for MPs to degrade into smaller particles. Ecological risk assessments using pollution load index, pollution hazard index, and potential ecological risk index models revealed varying levels of risk. This study conducted a comprehensive assessment of the ecological risks of MPs based on their environmental characteristics, emphasizing the importance of considering multiple factors in the risk assessment process. ENVIRONMENT IMPLICATION: This study investigates the occurrence, distribution, and ecological risk of microplastics (MPs) in agricultural soils of the Northeast Plain of China, a major food production area. MPs are persistent organic pollutants that can pose threats to soil health, crop quality, and food security. By analyzing the composition, size, and source of MPs, as well as their fragmentation and stability in soil, this study provides valuable data for assessing the environmental risk of MPs in agricultural regions. The study also suggests strategies for mitigating MPs pollution and protecting soil ecosystems.