Yi Caiwen¹，Chen Binghui^1,2，Li Wen¹，Zhou Yanmei¹，Wang Zhimei³，Zhang Jietang¹，ChengYinying¹，Zou Zhihui³

（1. School of Earth Science and geological engineering, Sun Yat-sen University, Guangzhou 510275, China;
2. Guangdong Provincial Key Laboratory of Geological Processes and Mineral Resource Survey, Guangzhou 510275, China;
3. School of Public Health, Guangdong Pharmaceutical University, Guangzhou 510310, China)

Abstract: Water and precipitation samples were collected from 9 sampling positions under various pH conditions by acid main drainages (AMD) in Caoduikeng and Tielong tailing ponds of Dabaoshan polymetallic mine, north Guangdong Province, China. Rare earth elements (REE) of the samples and some heavy metallic elements of water samples were measured to study REE geochemical characteristics of AMD and effects of pH value on REE concentration and distribution in AMD. It was investigated that REE is enriched with high ratios of LREE/HREE in acid water samples. Total REE contents of the water samples from Caoduikeng tailing pond lie in between 115.71 and1307.68 μg/L with ratios of LREE/HREE between 7.45 and 13.59. Total REE contents of water samples from Tielong tailing pond lie in between 6.86 and 2498.83 μg/L, with ratios of LREE/HREE in the range of 6.32~10.98. The REE in the water samples, distributed in a slightly right-leaning NASC-normalized pattern with positive Gd anomaly, is similar to REE chondrite-normalized pattern of the precipitations, but with a positive anomaly of Ce. Concentration of REE in water is affected obviously by the pH value. The lower the pH value is, the higher the concentration of REE will be. The REE content increases apparently to higher than 812 μg/L under the condition of pH＜3. The critical pH value that affects REE behavior in the MAD would be 3. It is not only beneficial for REE enrichments in water but also make the differentiation of REE enriched in Ce and middle rare earth elements (MREE), for acidic condition of pH＜3. Both REE and measured heavy metallic elements such as Cu, Pb, Zn, Mn and Cd enrich in waters with pH＜4, indicating that a stronger acidic environment is beneficial for the enrichments of REE and heavy metallic elements.

Key words: acid mine drainage; rare earth element, heavy metal, Dabaoshan Mine, Guangdong Province

EARTH AND ENVIRONMENT Vol. 44, No.1 Tot No.309, 2016, Page 73-81