The Mn~(2+) mass concentrations in the river,well water,soil and sludge of the river around the Dabaoshan Mine of Guangdong province were examined,and distribution and seasonal changes of manganese contamination were studied with respect to water quality,physical and chemical weathering and seasonal variations.The results showed that there were four types of water quality in Dabaoshan Mine: Ca-SO_4,Mg-SO_4,Ca-Mg-SO_(4)and Ca-HCO_3,among which the Mn~(2+) mass concentration in water quality type of Ca-SO_4 was the highest,being up to 339.003 mgL.SO_4~(2-) mass concentration was more than(2000)(mgL) when Mn~(2+) mass concentration of the water was greater than 21.300(mgL.) Within the same sample place,the Mn~(2+) mass concentration in water was related to water acidity;the more acidic the water,the higher mass concentration of Mn~(2+) was.The distribution of manganese content in the tailings profile followed the U-shape pattern in both the dry and rainy seasons.The manganese content of steam sludge in the mine area in the dry season followed the order: upsteam mid-stream downstream,but in the rainy season the order was opposite.The manganese cumulative effect was also found in the paddy field soil samples.

Fluoride concentrations in tailing and river systems in the vicinity of Dabao Shan mine, Guangdong province, were analyzed; Fluoride source and distribution were depicted by water quality classification, and dissolving experiments were taken in the laboratory to provide further evidence of fluoride source. The results showed 4 types of water existed in the vicinity of Dabao Shan mine: Ca-SO4, Mg-SO4, Ca-HCO3 and Ca-Mg-SO4, and Mg-SO4 is the primary type with highest fluoride concentration which can reach as high as value 16.68 mg/L; From the temporal and spatial distribution, fluoride concentrations has a clear seasonal and geographical characteristics, is lower in rainy season than in arid season; Moreover, fluoride concentrations decrease from the tailing reservoir to Weng river, indicating that fluoride comes from the mining area. The dissolving experiment results showed acidification of Tailing soils is severe. Sulfide oxidation promotes the dissolution of fluoride, which is proved by the changes of pH and SO42-concentration in the dissolution solutions; Fconcentration of topsoil decreased in the following order: topsoil of Caodui Keng tailing sand reservoir efflux river sediment of Tielong tailing sand reservoir rice-land soil of Shangba village, and in Caodui Keng tailing sand reservoir, F-and easily soluble fluoride concentration of stratified soil decrease in the same order: topsoil 0.5 m from the surface 1 m from the surface; these results further suggestted that the fluoride resource was the mine area.

The preventive maintenance fog seal is easy and effective for pavement preservation.There is not enough systematic evaluation for the effects of fog seal until now.According to a highway experiment road,some performance indexes of pavement are measured locally before and after applying fog seal.The construction technology of some fog seal treatments is introduced,all kinds of data analyzed, and the effects of fog seal evaluated.The data indicate that although the using of fog seal will reduce lightly the skid resistance,it will not influence the using function,and it will enhance the waterproof effect obviously,its construction technology is easy.