Abundances of elements in global coals

Abstract

The abundance of elements in coal is important not only because it provides a solid scientific and practical foundation for various geochemical comparisons, but also because it helps address broader questions in Earth Sciences. In this study, data on major and trace elements in global coals comprising hundreds of thousands of coal samples were compiled from peer-reviewed journal articles, books, various databases, dissertations, and technical reports. These data formed the basis for estimating element abundances in global coals presented in this study. All collected data were rigorously screened for reliability, and any records with questionable quality were excluded from the analysis. Boxplot analysis was then applied to estimate element abundances, and median values of ash yields and different forms of sulfur in global coals. The results primarily include the minimum and maximum values within the normal range; the median (the 50^th percentile, representing the average abundance); and outliers for all global coals, low-rank coals, and medium- to high-rank coals. Additionally, these statistical parameters are also provided for coals from different major coal-forming periods (including Pennsylvanian (Late Carboniferous) and Early Permian, Late Permian, Late Triassic, Early and Middle Jurassic, Late Jurassic and Early Cretaceous, and Paleogene and Neogene), and Chinese coals and U.S coals.