Progress in the research of trace elements in sapropelic coal of China

Coal is the main energy source in China whose extensive use will cause a series of environmental problems, especially the migration and precipitation of its harmful trace elements. Although there is already a relatively complete research system of trace elements in coal, its trace element geochemistry research is far less developed than that of humic coal, due to the secondary economic status of sapropel. The extensive and thick distribution of sapropelic coal gives it a certain industrial value, and the content characteristics of trace elements in sapropelic coal have been partially reported. However, the modes of occurrence, enrichment mechanism and geological origin of trace elements in sapropelic coal need to be systematically studied. Therefore, based on the comprehensive analysis of domestic and foreign research on sapropel, this paper elaborates the hot issues, key contents and development direction of trace element geochemistry of sapropel. The geochemical research on sapropel is a supplement and improvement of coal geology and coal geochemistry theory, which has important scientific significance, It is also of great practical significance as its beneficial to the theoretical system of coal formation and resource development of special coal in China.