LI Qian1, QIN Fei1, JI Hong-bing1,2,3*, LI Cai1, FENG Jin-guo4
(1.Civil and Environment Engineering School, University of Science and Technology, Beijing 100083, China;
2. The State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China;
3.The Key Laboratory of Metropolitan Eco-Environmental Processes, College of Resource Environment and Tourism, Capital Normal University, Beijing 100048, China;
4. Beijing Geo-engineering Design and Research Institute, Beijing 101500, China)
Abstract: A total of 34 surface soil samples were collected in the gold mine soil in the upstream area of the Miyun Reservoir. The contents of REE in soil were determined by inductively coupled plasma mass spectrometry (ICP-MS), and the distribution characteristics of REE in different particle size fractions were investigated. Then, the influencing factors, accumulation effect, distribution patterns and fractionation characteristics of REE were studied. The results showed that the average content of total REE in soil was just over the Chinese soil background value. The contents of REE and TOC in soil particle size fractions generally increase with decreasing particle size. Correlation analysis indicated that all REEs showed a similar correlation, REEs were positively correlated with Li, V, Co, Ga, Rb, Cs and TOC, while Cu, Cd, Pb and pH had a negative correlation with REE; pH, organic matter and mineral composition of soil were closely correlated with the distribution of REE contents. Accumulation factor (AF) analysis suggested that REEs were mainly accumulated in the fractions of clay (0-2 µm) and silt (2-50 µm). The high concentrations of REE occurred in fine size fractions due to larger surface area, high clay minerals and organic matter amount associated with fine particles. The chondrite-normalized patterns of REEs showed that the different soil fractions had similar distribution patterns, exhibiting no Ce anomaly and a clear loss of Eu, which were more serious in the ＞50 µm fractions than in fine fractions. The LREE/HREE fractionation showed that the relationship of their fractionation degree was: sand fraction (50-350 µm) > silt fraction (2-50 µm) > clay fraction (0-2 µm). The results of this study provided a scientific basis for rare-earth elements being selected as tracers, and it also provided references for the further study of REEs in various particle size fractions internationally.
Key words: gold mining region; soil; rare-earth element (REE); particle size fraction; geochemical characteristic
EARTH AND ENVIRONMENT Vol. 42, No.6, Tot No.302, 2014, Page 733-741
