Freshwater microplastics pollution: Detecting and visualizing emerging trends based on Citespace II

Microplastic particles with less than 5 mm in diameter has been detected in human feces and freshwater systems. Microplastics could cause serious physical and chemical harm to humans and organisms. Some previous studies on microplastics mainly concentrate on the marine environment, but few have focused on freshwater microplastics. Therefore, Citespace II is used to systematically analyze the related literature in order to comprehensively understand the research state of freshwater microplastics. The results show that there is still a large gap between research on freshwater and marine microplastics. Studies on freshwater microplastics have mainly been undertaken in developed countries such as the United States and Germany, while fewer studies have been conducted in the developing countries which face the most serious plastic pollution. Most studies focus on the rivers and lakes, but other freshwater sources with microplastic pollution, such as groundwater and reservoirs, have received less attention. This study also explored the possible opportunities and challenges that may be faced in freshwater research in order to introduce specific policies and measures to mitigate this emerging pollutant. (C) 2019 Elsevier Ltd. All rights reserved.