The Fluorine release rate of coal, clay of different Fluorine content, and coalmixed with clay used by resident households were studied by using the ion selective electrode(ISE) and solidoid balance methods, and the degree of influence on Fluorine pollutiongenerated by coal and clay was analyzed according to the proportion characteristicsof coal used by resident households.The results show that the Fluorine release rate ofcoal is more than 95% during combustion; The Fluorine release rate of clay is more than99%; The Fluorine release rate of coal mixed with clay is between 56.44% and 96.64%,and the average value is 76.68%.The clay as a binder for fine coal is one importantsource of Fluorine pollution caused by coal-combustion in Zhaotong, Yunnan Province.When the Fluorine content of coal is less than 80 mg/kg, the Fluorine amount releasedfrom clay (in which Fluorine content is more than 530 mg/kg) is more than 50% of the totalFluorine amount released from coal and clay during coal-combustion.The Fluorineamount released from clay (in which Fluorine content is more than 1 000 mg/kg) is morethan 70% of total Fluorine amount released from coal and clay during coal-combustion.
The Ediacaran and early Cambrian black shales are widespread across the South China Craton(Yangtze and Cathaysia blocks). However, the trace element distribution patterns of the Ediacaran and early Cambrian black shales in the Cathaysia Block are still unclear. In this study, thirtyfour black shale samples in the Lechangxia Group(Ediacaran) and thirteen black shale samples in the lower Bacun Group(early Cambrian) from Guangning area, western Guangdong Province, South China, were analyzed for major and trace elements concentrations. Compared to the upper continental crust, the Ediacaran black shales exhibit strongly enriched Se, Ga, and As with enrichment factor values(EF) higher than 10, significantly enriched Bi and Rb(10>EF>5), weakly enriched Mo, Ba, Cs, V, In, Be, Tl, and Th(5>EF>2), normal U, Cr, Cd, Sc, Pb, Cu, and Li(2>EF>0.5), and depleted Ni, Zn, Sr, and Co. Early Cambrian black shales display strongly enriched Se, Ga, and As, significantly enriched Ba, Bi, and Rb, weakly enriched Mo, Cs, Cd, V, U, Be, In, and Tl, normal Sc, Th, Cr, Li, Cu, Ni, and Pb and depleted Co, Zn, and Sr. Moreover, Se is the most enriched trace element in the Ediacaran and early Cambrian black shales: concentrations vary from 0.25 to 30.09 ppm and 0.54 to 5.01 ppm, and averaging 4.84 and 1.72 ppm, with average EF values of 96.87 and 34.32, for the Ediacaran and early Cambrian shales respectively. The average concentration of Se in the Ediacaran black shales is 2.8 times higher than that of early Cambrian black shales. Se contents in the Ediacaran and early Cambrian black shales exhibit significant variation(P = 0.03). Provenance analysis showed that Se contents of both the Ediacaran and early Cambrian black shales were without detrital provenance and volcanoclastic sources, but of hydrothermal origin. The deep sources of Se and the presence of pyrite may explain the higher Se contents in the Ediacaran black shales. Similar with the Se-rich characteristics of the contemporaneous black shales in the south Qingling Mountain and Yang
