Effects of Ion-Absorbed Rare Earth Deposits Mining on the Hydrochemical Environment in Ore Districts and its Vicinity — Case Study of Longnan Rare Earth Mine, Jiangxi Provence, South China

The ion-absorbed rare earth deposit occurred in the South of China is unique all over the world. Since the 1970s, rare earth in Longnan, South China has begun to be mined with leaching methods using oxalates and ammonium sulfate. Although this kind of methods is simple and economic, its presence in the environmental causes a growing environmental problems, especially changes in regional hydrochemical environment. In this paper typical ion-absorbed rare earth deposit——the Longnan rare earth mine, Jiangxi Provence, South China was selected as the study object, where the surface water and groundwater samples were collected. Analytic results show that the mining activities have affected the regional hydrochemical environment, which are expressed in the decreased pH（pH 3-4）, the enrichment of REE and heavy metal Pb in water with the maximum of 44760.1 μgL-1 and 1550 μgL-1 respectively, and the sulfate（214-1121 mgL-1）, ammonium（33.7-268 mgL-1） and nitrate ions（90-468 mgL-1） far beyond the background value. The impaction of the mining area surface hydrochemical environment is severest, then around the mining area, and the main rivers and groundwater in the study area have not been affected yet.