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As the main industrial uranium minerals in hydrothermal uranium deposits, uraninite and pitchblende are of great significance in the study of ore genesis and metallogenic regularity of hydrothermal uranium deposits. The Datian area in Panzhihua is one of the important areas of migmatite type hydrothermal uranium deposit in China. There is ultra-rich-uranium ore (U>10%) in rolling stone and the richer uranium-rich bedrock ore (U=0.1%-2%) where uraninite is the main uranium mineral. The study of the composition and forming age of two types of uraninite has important significance for metallogenic regularity of mixed rock type hydrothermal uranium deposits in the Datian area. In this study, mineralogical and Electron Microprobe analyses of uraninite in rolling stone and bedrock from the Datian area were carried out to determine the composition and age. Results show that the chemical compositions of uraninite in rolling stone and bedrock are similar except Pb contents with UO2 contents of 77.36%-84.04%, ThO2 contents of 0.98%-5.59%, and PbO contents of 1.79%-8.8%. Lead contents of uraninite in rolling stone are lower than those of uraninite in the bedrock, but thorium contents are contrary. Electron Microprobe chemical dating indicates that the uraninite in bedrock ore has ages of 774.9-785.5 Ma, whereas the uraninite in rolling stones has an age of 783.7 Ma. The dating results are consistent with traditional isotopic dating (775-777.6 Ma). The indicates that the uraninite in rolling stones and bedrock formed at the same time and the electronic probe in situ dating method is credible. In the late hydrothermal alteration, the uraninite experienced silicification, carbonization, and hematitization at 730.6 Ma, 699.8 Ma, and 664.0 Ma, respectively. This study provides evidences for the metallogenic epoch and mineralization process of the hydrothermal uranium deposits.

In order to find the effect of phosphorite resource exploitation on the natural radionuclide of water around the mining area, taking Yangshui River of Kaiyang phosphate deposit in Guizhou as the research target, the mass concentrations, mass fractions and distribution characteristics of uranium and thorium from water and surface sediment were measured and analyzed, and the ecological risk of uranium in the sediment was assessed by potential ecological risk index method. The results show that because of phosphorite resource exploitation, average mass concentration of uranium(0.958 44ng·mL-1) from water in Yangshui River is obviously higher than that in part rivers of China, and the mass concentration of thorium is extremely low (approximately zero), and the uranium is rich in river water but thorium is not; mass concentration of uranium (2.87 ng·mL-1) from cooling water in mine is 2.99 times more than that from river water; mass fraction of uranium (4.95×10-6)is 2.24 times more than the average background value of stream sediment in China, and mass fraction of thorium (5.43×10-6)is lower than the average background value of stream sediment in China, and uranium and thorium are equivalently rich in the sediment; average pollution index and potential ecological risk index of uranium in the sediment are 1.06 and 5.30, so that the pollution level is medium, and the potential ecological risk is moderate. [ABSTRACT FROM AUTHOR]

Land-use planning has triggered debates on social and environmental values, in which two key questions will be faced: one is how to see different planning simulation results instantaneously and apply the results back to interactively assist planning work; the other is how to ensure that the planning simulation result is scientific and accurate. To answer these questions, the objective of this paper is to analyze whether and how a bridge can be built between qualitative and quantitative approaches for land-use planning work and to find out a way to overcome the gap that exists between the ability to construct computer simulation models to aid integrated land-use plan making and the demand for them by planning professionals. The study presented a theoretical framework of land-use planning based on scenario analysis (SA) method and multiagent system (MAS) simulation integration and selected freshwater wetlands in the Sanjiang Plain of China as a case study area. Study results showed that MAS simulation technique emphasizing quantitative process effectively compensated for the SA method emphasizing qualitative process, which realized the organic combination of qualitative and quantitative land-use planning work, and then provided a new idea and method for the land-use planning and sustainable managements of land resources.