Global status, risk assessment, and knowledge gaps of microplastics in groundwater: A bibliometric analysis

Microplastics pollution is little studied in groundwater, compared to other surface water environments. In this review, bibliometric tools were used to determine literature trends and investigate research interests to provide a comprehensive knowledge on this research topic. 215 articles, published between 2009 and 2024, were obtained from the Scopus database, and their bibliometric data were statistically analyzed using the ‘bibliometrix’ package in R, to determine annual productivity, countries, authors, sources and citations. The co-authorship map and keywords co-occurrence analysis were obtained using VOSviewer and SCImago Graphica interfaces. Samples collection, methods, abundances, and polymers type differed significantly across research. Furthermore, keywords extraction revealed that only a minor fraction (4.6 %) of the total number of articles concerned drinking water sources and ecological risk assessment. This is a critical aspect of this field of research, as the contamination of drinking water sources could lead to the ingestion of microplastics, posing serious risk to biodiversity and human health. Furthermore, the absence of common legislation significantly affects the extent of this contamination. Monitoring studies of MP pollution in groundwater are necessary to develop targeted mitigation strategies to preserve human and environmental health. Finally, the lack of standardized protocols for sampling and analysis methods is a pressing need to encourage further studies on MPs in groundwater and to enable comparison of studies.