Abstract
Highly cited papers in the Essential Science Indicators database refer to papers with citations in the top 1% of all papers in a research field, and they are considered to be symbols of scientific excellence and top performance of the past ten years. This study provided an informetric analysis of 7791 highly cited papers in the environmental sciences category during 2009-2019. Informetric indicators and visualization tools were applied to evaluate and present the performances of journals, countries/territories, institutions, top cited papers, and research hotspots. The results showed that the cumulative number of publications has increased exponentially, suggesting strong development of the environmental sciences category. There were 211 journals publishing highly cited papers, with Energy & Environmental Science as the leading journal. The USA ranked first with the highest number of publications and occupied the core position in the collaboration network, while Mainland China took the first place in independent research output. Review articles have an obvious advantage in terms of achieving high citations. "Adsorption", "climate change", and "heavy metal" were the most frequent keywords, with "microplastic" rising rapidly as a new research frontier in recent years. Five research hotspots were visualized from highly cited papers via cluster analysis.