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Cao Y.,Beijing Forestry University | Wang B.,Beijing Forestry University | Wei T.,China National Gold Group Corporation | Ma H.,REPUBLIC RESOURCES
Environmental monitoring and assessment | Year: 2016

Populus davidiana, Leuchtenbergia principis, and Pinus tabulaeformis are important greening tree species with a cosmopolitan distribution. However, the stoichiometric characteristics and element reserves of stands of these three species are not particularly clear. In this study, we conducted a plot-level investigation of forest stands of these species in the loess area; these have been closed forest stands more than 28 years. Trees were sampled from an area of 50 m × 20 m (in 6, 8, and 9 plots, respectively), which was sufficient for shrub (2 m × 2 m), herbal species, and litter (1 m × 1 m) investigations. The C, N, and P concentrations and the C:N:P stoichiometry in five different soil layers (0-10 cm, 10-20 cm, 20-30 cm, 30-50 cm, and 50-100 cm) and in the leaves, stems, branches, and roots of the plants were examined. The soil element concentrations and density were affected by soil depth. The element content had a significantly negative correlation with soil depth, and element density differed significantly among the soil layers. A particular element in a particular organ differed significantly between the forest stands, and the same element in different organs of the same stand was also significantly different. The C, N, and P element reserves in the soil were considerably higher than in the plants. Our results indicate that there are different stoichiometric characteristics and element reserves of the three stands in a closed forest on the Chinese loess plateau, which may provide a reference when we develop and optimize the structure of forest stands. Source


Chen Q.,Central South University | Zhang Q.,Central South University | Wang X.,Central South University | Xiao C.,Central South University | Xu D.,China National Gold Group Corporation
Zhongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Central South University (Science and Technology) | Year: 2015

In order to reduce the cost of flocculating sedimentation of unclassified tailings and improve the effect of sedimentation, magnetized water was introduced to the flocculating sedimentation experiment of unclassified tailings from a mine. The effect of magnetized water on flocculating sedimentation was explored. Furthermore, the changing laws of flocculating sedimentation velocity and mass fraction of underflow of unclassified tailings were researched under different magnetization conditions. The results show that in the progress of flocculating sedimentation of magnetized water-unclassified tailings, the saturation point of the unit consumption of flocculants (sedimentation velocity is maximal) is 1/3 lower than that of tap water. Moreover, the increasing amplitude of sedimentation velocity and mass fraction of underflow are 1.4-2.1 times and 3.2%, respectively. Besides, flocculating sedimentation has the best effect when the magnetic induction B is 150-200 mT, magnetized time t is 20-25 min, and cycling rate of water v is 2.0-2.5 m/s. Therefore, magnetized water is capable of reducing the unit consumption of flocculants and improving the sedimentation velocity and mass fraction of underflow under the condition of suitable magnetization. © 2015, Central South University of Technology. All right reserved. Source


Cao Y.,Beijing Forestry University | Wang B.,Beijing Forestry University | Wei T.,China National Gold Group Corporation | Ma H.,Guangxi Institute of Water Resources Research
Environmental Monitoring and Assessment | Year: 2016

Populus davidiana,Leuchtenbergia principis, and Pinus tabulaeformis are important greening tree species with a cosmopolitan distribution. However, the stoichiometric characteristics and element reserves of stands of these three species are not particularly clear. In this study, we conducted a plot-level investigation of forest stands of these species in the loess area; these have been closed forest stands more than 28 years. Trees were sampled from an area of 50 m × 20 m (in 6, 8, and 9 plots, respectively), which was sufficient for shrub (2 m × 2 m), herbal species, and litter (1 m × 1 m) investigations. The C, N, and P concentrations and the C:N:P stoichiometry in five different soil layers (0–10 cm, 10–20 cm, 20–30 cm, 30–50 cm, and 50–100 cm) and in the leaves, stems, branches, and roots of the plants were examined. The soil element concentrations and density were affected by soil depth. The element content had a significantly negative correlation with soil depth, and element density differed significantly among the soil layers. A particular element in a particular organ differed significantly between the forest stands, and the same element in different organs of the same stand was also significantly different. The C, N, and P element reserves in the soil were considerably higher than in the plants. Our results indicate that there are different stoichiometric characteristics and element reserves of the three stands in a closed forest on the Chinese loess plateau, which may provide a reference when we develop and optimize the structure of forest stands. © 2016, Springer International Publishing Switzerland. Source


Zheng W.-B.,Chengdu University of Technology | Ling Q.-F.,Chengdu University of Technology | Chang Z.-S.,China National Gold Group Corporation | Ying L.-J.,Chinese Academy of Geological Sciences | Lin B.,Chengdu University of Technology
Journal of Chengdu University of Technology (Science and Technology Edition) | Year: 2011

The successful experiences in prospecting the Jiama deposit are used to guide the further work in prospecting the region. On the basis of the detailed prospecting and investigations, the Jiama deposit has been supposed to be the most typical and complete porphyry deposit system in the Gangdisi mineralization belt. This system includes the porphyry-type molybdenum, skarn-type copper-polymetal, hornfels-type molybdenum (copper) and peripheral self-golden ore-bodies. This paper studies the porphyry-type molybdenum, skarn-type copper-polymetal and hornfels-type molybdenum ore-bodies and describes their geological features in detail. And, combined with the geological studies and the previous research results, the paper makes a brief analysis of the origin and deposition process of Jiama molybdenum. Further, it proposes a system model of the Jiama porphyry deposit and recommendes it as a method to assess the regional prospecting. Source


Zheng W.-B.,Chengdu University of Technology | Li F.-J.,Chengdu University of Technology | Tang J.-X.,Chinese Academy of Geological Sciences | Song X.,China National Gold Group Corporation | And 4 more authors.
Geological Bulletin of China | Year: 2010

In this paper, putting the skarn-type ore body as the research object, according to the semi-variogram analysis of main internal symbol ore-grade in ore-body and establishing a corresponding spherical model, we get many parameters, as lag distance, nugget, variable-range, for the mainly variable directions of ore body. According to these parameters, the variation coefficients at every aspect of main elements, such as copper and molybdenum, in its copper-molybdenum ore body, are both 0.45. It indicates that both the main elements and the symbiotic elements in copper-molybdenum ore body have obvious coordinate changes in the direction of strike, tendency and vertical. While in the lead-zinc ore body, lead's variation coeffient is 0.58, and zinc's variation coeffient is 0.5, which indicates that they already have a certain randomness change in the direction of strike, tendency and vertical. Copper, molybdenum, lead and zinc, whose coefficients of grade change degree are all more than 0.9 in the direction of strike and tendency. It indicates that the ore's grade change degree is extremely complex in the ore body. The variation coeffient values of copper and molybdenum are both between 0.6 and 0.8 in the direction of vertical, showing their extent of changes are medium. And the lead and zinc's are between 0.3 and 0.6, showing that their degree of changes are relatively simple. Accordingly, we sum up the factors which control the ore body's change are mainly the cause of porphyry-skarn-type deposit, and there is a multi-stage mineralization during ore formation, to make useful minerals, ore-forming elements have a clear zoning. Source

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