LIU Wen-dong¹, LI Jin-juan^{*1, 2}, GUO Xing-qiang¹, JIANG Wu-ming¹

(1. College of Resources and Environmental Engineering, Guizhou University, Guiyang 550003,China;
2.State Key Laboratory of Coal Resources and Safe Ming, China University of Mining and Technology, Beijing 100083,China)

Abstract: Stove and fuel types used by local households were investigated in four poor villages (Yangguang, Xiongkuai, Guangming and Hongxing) in Nayong County, and samples of ash residues, foodstuff and indoor air were collected. The fluoride concentrations of these samples were determined by fluorine ion-selective electrodes and the contributions to fluorine pollution were analyzed. The results showed that easily-made open stoves and honeycomb briquette stoves with no chimney account for about for 87%, and coal briquettes and honeycomb briquettes used account for about 80.5%. The average fluorine contents in lump coal, powdered coal, coal briquettes and honeycomb briquettes are 57.85±27.64mg/kg, 83.03±47.10mg/kg, 199.41±113.61mg/kg, 83.11±44.16mg/kg, respectively. However, the average fluorine content of clay used in coal briquettes is 566.08±266.65mg/kg, including one sample whose clay content is as high as 1132.81mg/kg. The average contents of fluoride in chili, corn niblet and corn meal are 573.52±296.78mg/kg, 23.16±12.79mg/kg and 9.20±2.74mg/kg, respectively, with the highest value of 1273.92 mg/kg in the chili. The fluoride contents of indoor air in heating and non-heating periods are found to be 13.66±3.01μg/m³ and 1.28±0.76μg/m³, respectively. Fluorine release rates of coal briquettes and honeycomb briquettes are 66.31%, 43.76%, respectively. Based upon the results of this study, the main source of fluoride is still found to be clay binder and the important way by which fluorine is intaken into human bodies is by chili.

Key  words: endemic fluoride; fluorine pollution; coal combustion; clay binder; fluoride source