[Abundance and Physicochemical Characteristics of Microplastics in Surface Water and Sediments of Different Types of Waters in China].

Abstract

With the increase in plastic production and disposal volumes， microplastics have become a ubiquitous emerging pollutant in aquatic environments， attracting significant attention in recent years. Based on research data published in the past five years， this study analyzed the research areas focusing on microplastics in surface water and sediments of Chinese lakes， rivers， and oceans， as well as their abundance and physicochemical characteristics. It also summarized the distribution characteristics and influencing factors of microplastics in these three types of waters， with the aim of providing references for the governance of microplastic pollution and environmental regulation. The results showed that the distribution of research areas on microplastics in China's waters was uneven， with less research conducted in the northwest， northeast， and southeast regions and remote sea areas. The highest abundance of microplastics in the surface water of lakes， rivers， and oceans in China reached 51 340， 930 200， and 726 000 n·m^-3， respectively. The highest abundance （dry weight） of microplastics in sediments was 6 374.55， 18 780.20， and 54 813.20 n·kg^-1， respectively. Among all lakes， the abundance of microplastics in lakes in the eastern and western regions was higher than that in the central region. In river systems， the Yellow River and Songhua River systems showed higher average microplastic abundance in surface waters compared to that in other river systems， whereas the Huaihe River and Haihe River systems demonstrated relatively higher levels in sediments. For marine environments， the South China Sea and Yellow Sea contained elevated microplastic abundance compared to that in the Bohai Sea and East China Sea. The abundance of microplastics was significantly positively correlated with the gross regional product， the total output value of industry， the total output value of agriculture， the total output value of fisheries， population， and sewage discharge. Microplastics smaller than 1 mm predominated in both surface waters and sediments， with transparent or colorless microplastics being the most prevalent. Fibers and fragments represented the most common morphological types， while polyethylene， polypropylene， and polyethylene terephthalate constituted the predominant polymer categories. However， the research areas of microplastics in China's waters are insufficiently covered. In summary， microplastics are widely distributed in China's water bodies and exhibit significant spatial heterogeneity. Their abundance and physicochemical characteristics are closely related to human activities. This study provides theoretical support for the control of microplastic pollution in water bodies and the analysis of the impact of human activities on their abundance.