Fig. Relationship of sulfur contents (a), the δ34S values (b), nitrogen contents (c) and the δ15N values (d) with the boron contents in Chinese coals. The classification of boron contents is based on the method proposed by Goodarzi and Swaine (1994). Different letters above the bars indicate a significant statistical difference between means at the level of p < 0.05.

Coal combustion is an important atmospheric pollution source in most Chinese cities, so systematic studies on sulfur and nitrogen in Chinese coals are needed. The sulfur contents in Chinese coals average 0.9 +/- 1.0%, indicating that most Chinese coals are low in sulfur. A nearly constant mean delta S-34 value is observed in low sulfur (TS < 1) Chinese coals of different ages (D, P-1, T-3 and J(3)). High sulfur Chinese coals (OS > 0.8%), often found at late Carboniferous (C-3) and late Permian (P-2) in southern China, had two main sulfur sources (original plant sulfur and secondary sulfur). The wide variety of delta S-34 values of Chinese coals (-15 parts per thousand to +50 parts per thousand) is a result of a complex sulfur origin. The delta N-15 values of Chinese coals ranged from -6 parts per thousand to +4 parts per thousand, showing a lack of correlation with coal ages, whereas nitrogen contents are higher in Paleozoic coals than in Mesozoic coals. This may be related to their original precursor plant species: high nitrogen pteridophytes for the Paleozoic coals and low nitrogen gymnosperms for the Mesozoic coals. Different to, delta S-34 values, Chinese coals showed higher delta N-15 values in marine environments than in freshwater environments. (C) 2010 Elsevier Ltd. All rights reserved.　　　

Publication name	ORGANIC GEOCHEMISTRY　　Volume: 42　　Issue: 1　　Pages: 84-93　　Published: JAN 2011
Author(s)	Xiao, Hua-Yun, Liu Cong-Qiang
Corresponding author	XIAO Huayun  xiaohuayun@vip.skleg.cn  Chinese Acad Sci, Inst Geochem, State Key Lab Environm Geochem, Guiyang 550002, Peoples R C