Fluoride in drinking water, brick tea infusion and human urine in two counties in Inner Mongolia, China.

The objective of this study was to detect the fluoride level in the drinking water and the urine of habitants aged 16-55 years living in Inner Mongolia China. Furthermore, fluoride concentration of the brick tea infusion samples which were drunk by Mongolia herdsmen in everyday life living in SumuErga village of Ejin Horo Banner, Inner Mongolia China was also determined. A total of 117 participants (61 female and 56 male) were recruited from two counties for a cross-sectional study on health effects of chronic fluoride exposure from drinking water and drinking brick tea infusion. The fluoride concentration in drinking water, urine and brick tea infusion samples were determined using fluoride ion selective electrode method obtained from the Ministry of Health of the People's Republic of China. The average fluoride concentration in drinking water samples was 0.32+/-0.01 mg/L at AretengXire town of Ejin Horo Banner, 0.70+/-0.19 mg/L at SumuErga village of Ejin Horo Banner, and 2.68+/-1.15 mg/L at ZhalaiNuoer district of Manzhouli city. The average fluoride concentration in brick tea infusion samples which collected from Mongolia herdsmen at SumuErga village of Ejin Horo Banner was 1.81+/-1.09 mg/L. The average urinary fluoride concentration at AretengXire town of Ejin Horo Banner was 0.59+/-0.48 mg/L, at SumuErga village of Ejin Horo Banner was 1.45+/-0.93 mg/L and at ZhalaiNuoer district of Manzhouli city was 3.06+/-1.53 mg/L. The higher fluoride levels in the urine of participants may be associated to higher fluoride in drinking water at ZhalaiNuoer of Manzhouli city. However, drinking brick tea infusions with higher fluoride may be the cause of the higher fluoride contents in the Mongolia herdsmen's urine.

[Sequential extraction experiments applied to study chemical mobility of fluorine in rocks].

Sequential extraction experiments were used to study the chemical mobility of fluorine in rocks. The results show that there are quite big differences in chemical mobility of fluorine in rocks of different types. Fluorine in carbonate rock is very active, in which the proportion of leachable fluorine is generally more than 75%. Fluorine in black rocks of Lower Cambrian is closely related to their different metamorphosed grades, in which fluorine in black carbonaceous slate with higher metamorphosed grade mostly has lower leachability than black shale and black siliceous rock. Generally speaking, the leachable percentage of fluorine is high in phosphorite rocks and low in phyllite. The leachable fluorine in diabase is in direct proportion to its fluorine concentration. There are some differences in chemical mobility of fluorine in stone coal of different ages. Fluorine in stone coal of Silurian has higher leachability than stone coal of Cambrian.

[Pilot experiment of fluorine fixing ratio of coated lump stone coal fuel].

The pilot experiment on coated lump stone coal fuel selected from 16 families in Haoping Shanxi were studied. 8 families burned coating high fluorine lump stone coal with lime, clay and low fluorine anthracite, 8 families burned untreated lump stone coal. The results show that the fluorine-fixing ratio at treated group was 75.0% when coal fluorine compared with coal cinder fluorine. In comparison with untreated group, the concentration of door air fluoride lowered 85.7%, SO2 lowered 75.0%, dust lowered 55.3%.

[Regularity of flourine release from fluorine-rich coal combustion in the fluorine poisoning area].

Laboratory experiments and in situ measurements inside farmer's houses indicate that the fluorine concentration of indoor air was positively related with the fluorine content in the consumed coal (R = 0.612, P<0.01), but fluorine content in the coal had no effect on the release rate of coal fluorine under the usual combustion temperature of about 1000 degrees C. The release rate of coal fluorine varied versus combustion temperature ranging from 200 to 1200 degrees C, following a "S" curve pattern, increasing slowly under 300 to 700 degrees C, but quickly under 700 to 1000 degrees C, and then slowly again before finally reaching 100% under 1100 to 1200 degrees C, this curve can be fit by Logistic equation. The release rate of coal fluorine usually depends upon the existence status of fluorine and the chemical and mineral components of the coal. The fluorine in soft coal or anthracite from Guizhou is released more quickly than in bone coal from Southern Shanxi, with the former almost completely released under 1100 degrees C but the later almost completely released under 1200 degrees C. The combustion temperature of civil stoves is at most 1000 degrees C, under which averagely 86.9% of the fluorine in coal from Guizhou and 80.6% of that in bone coal from Southern Shanxi is released.