Wu Dun, Zhao Liu, Li Bo, Kataza Nyasha Ndhlovu
Anhui Province Intelligent Underground Exploration and Environmental Geotechnical Engineering Research Center, College of Civil Engineering, Anhui Jianzhu University, Hefei, 230601, China.
School of Earth and Space Sciences, University of Science and Technology of China, Heifei, 230026, China.
Sci Rep. 2025 May 30;15(1):19095. doi: 10.1038/s41598-025-03810-1.
This study focuses on Coals 8 and 9 of the Late Carboniferous Taiyuan Formation in the eastern part of the north China Craton Basin. Through comprehensive industrial analysis, XPS, and nitrogen isotope techniques applied to 16 collected coal samples, the distribution of nitrogen in coal and the differentiation mechanism of δN values were revealed. The results indicate that most coal samples exhibit high ash content, high volatile matter, and ultra-low moisture. Nitrogen exists in an organic state, with N-5 dominating and N-6 being secondary. The δN values range from 0.72 to 3.15‰ for Coal 8 and - 1.90 ~ - 0.38‰ for Coal 9, deviating from China's typical range, with positive and negative differences between Coal 8 and 9. These isotopic differences are influenced by factors such as depositional environments and diagenesis. δN shows a negative correlation with total nitrogen content and a close association with macerals (negative correlation with vitrinite and positive correlation with inertinite). The deep-water reducing environment in the east and the shallow marine environment at the southern margin play regulatory roles in nitrogen isotope fractionation. This study provides crucial geochemical evidence for the reconstruction of ancient depositional environments and the nitrogen cycling mechanisms during coalification processes.
本研究聚焦于华北克拉通盆地东部晚石炭世太原组8号和9号煤层。通过对采集的16个煤样进行综合工业分析、X射线光电子能谱（XPS）和氮同位素技术，揭示了煤中氮的分布及δN值的分异机制。结果表明，多数煤样灰分高、挥发分高且水分超低。氮以有机态存在，以N-5为主，N-6为辅。8号煤的δN值范围为0.72‰至3.15‰，9号煤的δN值范围为-1.90‰至-0.38‰，偏离中国典型范围，8号煤和9号煤之间存在正负差异。这些同位素差异受沉积环境和成岩作用等因素影响。δN与总氮含量呈负相关，与煤岩组分密切相关（与镜质组呈负相关，与惰质组呈正相关）。东部的深水还原环境和南部边缘的浅海环境对氮同位素分馏起调控作用。本研究为重建古沉积环境及煤化过程中的氮循环机制提供了关键的地球化学证据。
