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Variation of Concentration, Form and Flux of Phosphorus in the Three Gorges Reservoir from 1998 to 2019
LOU Baofeng, YU Mingxing, HUANG Bo, YANG Yan, LIN Jingjing
Acta Scientiarum Naturalium Universitatis Pekinensis    2024, 60 (3): 548-562.   DOI: 10.13209/j.0479-8023.2024.027
Abstract2460)   HTML    PDF(pc) (1356KB)(93)       Save
The changes in total phosphorus (TP) concentration and form in the Three Gorges Reservoir (TGR) from 1998 to 2019 were studied, and P fluxes were calculated. The entire research period was divided into three stages: 1998–2002 (stage I, before the operation of the TGR), 2003–2012 (stage II, as a transitional period), and 2013–2019 (stage III, after the TGR achieved the normal water level of 175 m and Xiangjiaba Reservoir began to operate). Comparative analysis was mainly on Stages I and III. The results show that the concentrations of suspended sediment (SS) in the TGR decreased to a very low level (average 42 mg/L during 2013–2019 period and 96 mg/L in wet season). From 1998 to 2019, the inflow and outflow of sediment amount showed a downward trend. A huge amount of sediment was retained at the bottom of the reservoir during 2003–2012 (average 154.6 million t/a), while in 2013–2019, the amount of sediment deposition significantly decreased and the sedimentation amount was only 37% of that in 2003–2012. Year 2013 marked a turning point in the trend of phosphorus pollution in TGR from increasing to decreasing. Afterwards, concentrations of TP and DP (dissolved phosphorus) showed a significant downward trend. The form of phosphorus in TGR changed from mainly granular to dissolved, and the percentage of DP in TP in the perennial backwater area increased from 39% before TGR formation to 69% during 2017–2019. 2004–2012 was a period with high deposition for TP when the amount of TP entering the reservoir was large and fluctuated vastly between years, and approximately 60% of phosphorus was trapped (82220 t/a). From 2013 to 2019, there occurred significantly decrease in the TP amount entering the reservoir in accompany with diminishing interannual fluctuation, tending to a balance between input and output of P. Fluxes of TP, DP, and PP (particulate phosphorus) all show a pattern of wet season>even season>dry season. The main driving forces for changes in TP concentration, flux, and form are the reduction in SS concentration and phosphorus pollution level.
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Application of the Automated Event Location Using a Mesh of Arrays in Southern Ordos and Qinling-Dabie Orogenic Belt
YANG Yanzhao, GE Zengxi
Acta Scientiarum Naturalium Universitatis Pekinensis    2022, 58 (4): 626-634.   DOI: 10.13209/j.0479-8023.2022.045
Abstract1392)   HTML    PDF(pc) (28660KB)(665)       Save
The recently developed automated event location using a mesh of arrays (AELUMA) method is used to scan and locate the continuous waveforms recorded by 136 broadband mobile seismic stations in Ordos basin and its surrounding region. Compared with the seismic catalog provided by national earthquake data center, besides the events located in conventional seismic zone, a large number of events were located in Qingling-Dabie orogenic belt with few earthquakes in the catalog. The detected events were further confirmed through the bootsctrap analysis and carefully manual examination. The apparent velocities of these events were also obtained from slowness analysis. Most apparent velocities were 2.5-5.2 km/s which was consistent with the group velocity of surface wave propagation. The events detected and located in this paper can be a supplementary of the earthquake catalog and further used to determine the focal mechanism through waveform fitting.
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Mineralogical Characteristics of Aphanitic Cryptocrystalline in Yantongshan and Its Significance for Origin
CHENG Siyu, CHUAN Xiuyun, YANG Yang, LIN Chao, CHEN Siyu
Acta Scientiarum Naturalium Universitatis Pekinensis    2020, 56 (2): 242-252.   DOI: 10.13209/j.0479-8023.2019.126
Abstract2649)   HTML    PDF(pc) (38800KB)(683)       Save
By means of optical microscope, field emission scanning electron microscope, X-ray diffraction and laser Raman spectroscopy, the mineralogical characteristics of cryptocrystalline graphite in Yantongshan, Jilin Province and its indication significance for the genesis of the deposit are studied. The diameter of graphite microcrystals is La=59?175 nm, and the stacking height is Lc=32?93 nm. The graphitization degree value ranges from 0.573 to 1.000, and the interval (002) layers vary from 0.3352 to 0.3370 nm. The intensity ratio of D1 peak and G peak arranges between 0.07 to 0.28. On the base above, the metamorphic temperature range was calculated as 526℃ to 622℃, with the average is 561℃, indicating that the metamorphic degree could reach the amphibolite facies in its formation. The graphitization degree varied greatly, and much higher near Fe bearing minerals, indicating that the crystallization process of graphite could be catalyzed with the different spots of one graphite ore slice by Fe containing compounds.
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An ICA Based Method for Grid Radio Signal Monitoring
ZHANG Jingshu, Lü Mengfei, LI Dou, YANG Yanjun, ZHAO Yuping
Acta Scientiarum Naturalium Universitatis Pekinensis    2018, 54 (2): 307-314.   DOI: 10.13209/j.0479-8023.2017.173
Abstract2521)   HTML141)    PDF(pc) (791KB)(908)       Save

An independent component analysis (ICA) based method is designed for improving the effect of grid radio monitoring and providing an effective layout of the monitoring system, in which the source signals can be retrieved and sudden emergence of abnormal signal sources can be detected. To analyze the multiple factors affecting the performance of the method, a MATLAB simulation modeling is built. The feasibility and efficiency of the proposed ICA based method are also demonstrated.

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Characterization of Soil Fungal Community in Response to Heavy Metal Pollution in Lead-Zinc Mining Area
Jinshui YANG, Yang YANG, Liangming SUN, Weijie LIU, Yuan ZENG, Chunping DENG, Guanlan XING, Hongli YUAN
Acta Scientiarum Naturalium Universitatis Pekinensis    2017, 53 (2): 387-396.   DOI: 10.13209/j.0479-8023.2016.122
Abstract3858)   HTML61)    PDF(pc) (2817KB)(1620)       Save

Heavy metal contamination is one of the most concerned global environmental problems and the soil heavy metal contamination is especially severe in lead-zinc mining areas in China. In order to study the soil fungal community composition changes responding to different degree of heavy metal pollution, soil samples from the lead-zinc mine field of Yunnan Mengnuo were studied. 5 samples from the heavy metal pollution soil (HP) and other 4 from the low pollution (LP), based on the cluster analysis of heavy metal contents and the physical and chemical properties of the sample were analyzed. Genomic DNA of the soil samples were extracted and the Internal Transcribed Spacer (ITS) genes were sequenced by the high-through sequencing Illumina MiSeq. The fungal communities at different taxonomic levels (Phylum, Class, Order, Family, Genus and Species) were compared. In HP samples, the abundance of unclassified fungi were the highest, then followed by Aspergillus, Un--s-Clavulinaceae sp. and Un--s-fungal sp. ARIZ L453 respectively. In LP samples, the unclassify fungi were also high, but less than HP. The relative abundance of fungi from high to low was Geastrum, Aspergillus and Mortierella. The Representational Difference Analysis (RDA) showed that different heavy metals influence fungal community diversity and the concentrations of Pb was significantly correlated with fungal community.

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Influence Major Factors Analysis of Comprehensive Air Quality in the Cities in China
YANG Yang, SHEN Zehao, ZHENG Tianli, DING Yuchen, LI Bengang
Acta Scientiarum Naturalium Universitatis Pekinensis    2016, 52 (6): 1102-1108.   DOI: 10.13209/j.0479-8023.2016.115
Abstract3160)   HTML    PDF(pc) (827KB)(2293)       Save

Based on the air quality data of five indices in 2010 for 78 main cities of China, the research calculated the comprehensive score of urban air quality, selected ten out of 48 variables describing the climate, topography, urban development and environment management of these cities with multivariate linear regression analysis, and quantified their contribution to the urban air quality. Based on the comprehensive score of urban air quality, the authors used a stratified random sample of 30 from the 78 cities, as a training sample, to construct a radial basis function network (RBFN) model, which was used to simulate air quality of 173 main cities in China based on the natural and social-economic features, and environmental management of the cities. The results indicated that the average saturation vapor pressure, built-up urban area, elevation range, and the percentage of industry in GDP as four major dominants of urban air quality, accounting for the variation by 14.7%, 12.8%, 8.8% and 7.2%, respectively. This study broke the limitation of most previous air quality assessment models, which merely took air pollutants and meteorological factors as input. The result showed a high accuracy (R2=0.658, p<2.2×10-14) of the RBFN model.

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Study on Depth of Atmospheric Boundary Layerin Gobi Desert Regions of the Bosten Lake Basin
YANG Yang, LIU Xiaoyang, LU Zhenghui, LI Hao
Acta Scientiarum Naturalium Universitatis Pekinensis    2016, 52 (5): 829-836.   DOI: 10.13209/j.0479-8023.2015.145
Abstract3474)   HTML    PDF(pc) (1148KB)(2504)       Save

Due to the combined effects of lake and Gobi, the atmospheric boundary layer located in Gobi desert regions of the Bosten Lake basin is found to possess some special regional characteristics. Based on the data of the developing meteorological observation experiments conducted in the Bosten Lake of Xinjiang Province, the height characteristics of the atmospheric boundary layer from May 21 to August 28, 2013 are analyzed. The result shows that the most prominent feature of the Gobi area of the Bosten Lake Basin is that the boundary layer often has the deep convection during the typical sunny days in the summer. The statistics also shows that in 45 days out of 100 days, the average height of the atmospheric boundary layer is above 3000 m, and the maximum height reaches 4400 m. The causes of forming the deep convective boundary layer are explored. It is argued that the atmospheric thermodynamic properties and the lake wind shear are important factors to form the deep convective boundary layer.

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Research and Application of the Three-Dimensional Complex Fault Network Modeling
LI Zhaoliang,PAN Mao,YANG Yang,CAO Kai,WU Gengyu
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract1807)      PDF(pc) (3411KB)(1534)       Save
For complex fault network, a new path cut algorithm was proposed, by which all types of complicated fault intersection can be dealt with, such as Y, λ, X, half-Y, half-λ contact relations. This fault modeling method not only avoids the limitation of the Pillar method and binary tree method, but also greatly improves the flexibility and accuracy of fault modeling. The method improves semi-automatic processing of the contact relationship between faults and quick updating of fault models. Through the validation of practical model, the modeling of complex fault network can be successfully and quickly solved, and the efficiency of modeling was also greatly improved.
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The Influence of Self-Activation on Local/Nonlocal Brand Evaluations
YANG Yangzi,HUANG Yunhui,SHI Junqi
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract1125)            Save
The current study examines, among consumers in developing countries, diverse modes of consumers′ evaluations toward local/nonlocal brands with different types of self-activation. To achieve this goal, brand and category familiarity, and prior experience of consumers with brand were controlled; and a 3 (self-activations: self-affirmation vs. self-threat vs. neutral self) × 2 (countries of origin: local vs. nonlocal) between subject design was used. The result shows a significant interaction between self-activations and countries of origin, which indicates inconsistent preferences of local/nonlocal brands among different types of self-activation. Particularly, individuals in the self-affirmation group tend to perform a superior evaluation of local brands to nonlocal brands, whereas individuals in the self-threatening group and neutral self group tend to perform a superior evaluation of nonlocal brands to local brands. These results could be explained by ethnic identity, nonlocal brands as status symbols in developing countries, and national stereotyping. This study gives further implications of consumer behaviors in developing countries, which helps us to learn more about the influence of mental factors in country-of-origin effect.
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Analysis of Satellite Image Characters of Severe Storm Rainfall During the Flood of Yangtze River in 1998
WANG Likun,TAO Zuyu,YANG Yang,MA Yu,WANG Xu
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract1374)            Save
By the daily, 5-day, 10-day, monthly and seasonal mean images from hourly GMS-5 infrared images, an analysis of cloud characters of severe storm rainfall during the flood of Yangtze river in 1998 was made. The results show that the mean cloud images disclose the mean features of the severe storm systems. These mean images reveal not only the synoptic cloud systems but also the mesoscale convective cloud cluster. The long-term high water level of mid-Yangtze river and the frequent flood peak of the upper Yangtze river from the middle of June to the middle of August in 1998 was caused by the high frequent activity of convection. The 5-day mean and daily mean images show that the long severe rainfall of Yangtze river was produced by the meso-α scale cloud clusters in the end of July. Additionally, there is somewhat possible correlation between the daily mean cloud image and the daily precipitation. The future research is possibly expected to estimate the flux of water by means of the TBB of the mean cloud images.
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