Table of Content

20 May 2021, Volume 57 Issue 3

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Development and Characterization of Polymorphic Microsatellite Markers in the Masked Palm Civet (Paguma Larvata)

WANG Di, ZHANG Dan, XIONG Mengyin, BU Hongliang, WANG Dajun, YAO Meng, LI Sheng, WANG Rongjiang

2021, 57(3):  395-400.  DOI: 10.13209/j.0479-8023.2021.038

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To provide genetic tools for individual identification of the masked palm civet (Paguma larvata) through DNA analysis, we selected a tissue sample from Laohegou Nature Reserve in Sichuan for constructing microsatellite library by FIASCO. Altogether 250 clones were sequenced and 147 sequences were found containing microsatellite motifs, in which there were 42 sequences with >10 motif repeats. Primer pairs were designed based on these 42 sequences. Through tests for amplification and polymorphism using additional 21 samples of masked palm civets, 5 polymorphic microsatellite markers were obtained. In the meantime, 13 microsatellite markers published previously were tested for the masked palm civet, and found 5 of them polymorphic. Collectively, these 10 markers showed relatively high polymorphism (number of alleles was 2–11, observed heterozygosity was 0.286–0.737, and expected heterozygosity was 0.358–0.906). The values of PID and PID-sib indicated that there would be individuals with completely identical genotypes in about 10⁹ unrelated individuals or 10⁴ related individuals. As the size of wild populations in a particular region was greatly lower than this number, these 10 microsatellite markers were sufficient for individual identification for the masked palm civet.

Study on Temperature Drift of Offset for Full-Bridge Magneto Resistive Sensors

YU Xiangqian, LIU Si, XIAO Chijie, QU Yanan, ZONG Qiugang, CHEN Hongfei, ZOU Hong, SHI Weihong, WANG Yongfu, CHEN Ao, SONG Siyu, GAO Shuang, SHAO Sipei

2021, 57(3):  401-406.  DOI: 10.13209/j.0479-8023.2021.028

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A concise quasi-linear model of the temperature offset for full Wheatstone-type bridges magneto resistive sensors is proposed based on the temperature-dependent of resistivity of four elements. In MATLAB environment, the simulation results of quasi-linear model agree well with the experimental results, indicating that the quasi-linear model is simple but efficient for the offset calibration, can explain the causes of the temperature offset for full Wheatstone-type bridges magneto resistive sensors, and can be applied to other sensors with full Wheatstone-type bridges structure.

Direct Synthesis of Graphene on 6H-SiC Assisted by Carbon Ions Implantation

CHEN Yuhan, ZHAO Ziqiang, ZHAO Yunbiao, CHEN Yi, ZHOU Danqing

2021, 57(3):  407-413.  DOI: 10.13209/j.0479-8023.2021.007

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In order to provide a more convenient and economical approach of graphene synthesis on semiconducting 6H-SiC, commercially available single crystalline 6H-SiC samples were implanted at room temperature with 5 keV carbon ions. The prepared samples were characterized by Raman spectroscopy, scanning electron microscope (SEM) and atomic force microscope (AFM). Moreover, the influences of cooling rates and the enclosed environment were investigated. A possible growth mechanism based on the Si sublimation was also put forward to explain the graphene growth. The results show that the graphite enclosure effectively control the Si sublimation and the cooling rate affects the precipitation and surface self-assembly of C atoms. Upon proper cooling, the implanted carbon atoms segregate to the surface and self-assemble into bilayer or multilayer graphene on 6H-SiC. This method reduces the annealing temperature to 1100℃ in vacuum condition without hydrogen etching, ultrahigh vacuum or special atmosphere, which is more cost-effective and efficient.

Meteorological and Pollution Characteristics of PM_2.5 under Atmosphric Circulation Types in Autumn and Winter in Shijiazhuang

XIAO Teng, LIN Tingkun, YAN Yu, WANG Xuesong

2021, 57(3):  414-424.  DOI: 10.13209/j.0479-8023.2021.021

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According to the ground and vertical meteorological characteristics of atmospheric circulation types during the autumns and winters (Nov.?Feb.) of 2013?2018 in Shijiazhuang, 11 types of atmospheric circulation were classified into five categories. The correlation between each category and PM_2.5 pollution was discussed by combining the transport trajectories and the air quality data. Among those categories, Category I (type NW and type N, accounting for 16% of days) was the best condition for air pollution diffusion, characterized by the dominant west or northwest winds near surface with steady direction and high speed, as well as high planetary boundary layer (PBL) height. Category II (type NE, accounting for 9%) and Category III (type E and type SE, accounting for 12%) were the second-best conditions, characterized by high wind speed. Category II was dominated by north wind and medium PBL height, while Category III was dominated by northeast wind and low PBL height. Category IV (type A, 37%) was unfavorable for air pollution diffusion, which was characterized by low-speed, near-surface winds and low PBL height. Category V (type UM, type C, type S, type SW, type W, 26%) was the worst condition, characterized by near-surface winds with low speed and variable directions, as well as low PBL height and intensive temperature inversion in lower atmosphere. The potential areas of sources contributing to PM_2.5 pollution in Shijiazhuang under different circulation types varied with different transport trajectories. Concerning the correlation between the PM_2.5 pollution in Shijiazhuang during the autumns and winters and the diffusive conditions of different circulative types, the PM_2.5 pollution tended to occur (the frequency of pollution was from 78% to 96%, and the frequency of heavy pollution and above was more than 55%) when the region was controlled by Category V; the condition of the PM_2.5 pollution tended to change slowly under Category IV, but the PM_2.5 concentration was more likely to increase under the continuous Category IV days; the frequency of PM_2.5 pollution was lowest under Category I.

Algorithm Optimization of First-Break Tomography Statics Based on Large Datasets

LÜ Xuemei, ZHANG Xianbing, KANG Ping, HU Tianyue

2021, 57(3):  425-434.  DOI: 10.13209/j.0479-8023.2021.034

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The development of 3D land seismic data acquisition in the direction of wide azimuth and high density will lead to huge dataset. The classical first arrival time tomography algorithms are not suit for processing huge seismic dataset due to very high memory request and computing time cost. In order to solve this problem, the authors develop an optimal mathematical formula from the classical first break travel time tomography method to avoid the memory occupation that required by Frechet derivative matrix and Hessian matrix, and reduce the time cost of computing Hessian matrix inversion. This method can efficiently solve the tomography inversion problem for huge datasets. It is suitable for huge and high-density land seismic exploration, and not affect the dataset and model accuracy. It is easy for parallel processing. Both the model and real data examples confirm the effectiveness of this method. It can provide reliable tomographic results for static correction when the first breaks reaches a certain amount.

Model Inversion of Velocity Structure for Slipstream Submarine Slide Related to Gas Hydrate

LAN Kun, ZHU He, HE Tao, LIANG Qianyong, WU Xuemin, DONG Yifei, ZHANG Yi

2021, 57(3):  435-445.  DOI: 10.13209/j.0479-8023.2021.005

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The RAYINVR software, which is widely used in academia for 2-D velocity structure model from fourcomponent OBS (ocean bottom seismometer) data, is unable to invert for the converted S-wave automatically, resulting in the low-efficiency of modeling process. Using MATLAB’s genetic algorithm, the RAYINVR software is improved and able to automatically and synchronously invert for Poisson’s ratios of each layer with all subblocks for the S-wave velocity structure model, and thus can provide Young’s modulus, Poisson’s ratio and other important mechanical information for gas hydrate survey. This method is applied to process the OBS data collected at the Slipstream submarine slide, and a fine P- and S-wave velocity structure model is obtained, which is comparable to the logging data of nearby borehole U1326. Therefore, the validity of the auto-synchronous inversion method is verified for the S-wave velocity structure modeling. The optimal velocity model reveals two structural interfaces with large Poisson’s ratio contrast. One is BSR (bottom simulating reflector) at 230±10 mbsf (meter beneath sea floor), which represents the bottom boundary of the gas hydrate stability zone, and the other is the basal boundary of a shallow abnormal high-speed body (possibly a sand body enriched with high saturation gas hydrate) at 75?100 mbsf. The latter agrees roughly with the glide plane of Slipstream submarine slide, indicating that the hydrate is related to the formation of submarine landslide.

REE Distribution Character in Skarn Garnet and Its Geological Implication

WANG Yichuan, DUAN Dengfei

2021, 57(3):  446-458.  DOI: 10.13209/j.0479-8023.2021.006

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The REE data in literature for garnet in skarn deposits are compiled to discuss main factors affecting the REE partition. The data shows that the garnet in skarn deposit is mainly grossular-andradite garnet. From the andradite to grossular, the garnet changes from LREE-enriched to HREE-enriched. In the LREE enriched type, with the decrease of andradite, the highest point in REE distribution diagram change from La-Ce through Ce-Pr to Pr-Nd. The statistic data show that the main factor affecting the REE pattern is the major composition of the garnet. The REE pattern of hydrothermal fluid and the other factors have little affection. REE usually enter dodecahedral site in garnet. With the increase of andradite, ideal radius of dodecahedral site increase accordingly, and garnet displays LREE-enriched and HREE-depleted features, for the larger ion radius of LREE than HREE. In the deposit with positive Eu anomaly fluid, most garnet also show positive Eu anomaly. The depletion of oxygen fugacity or increasing of salinity will elevate the Eu positive anomaly. Whereas the crystallization and dissolution of Eu enriched minerals can deplete and elevate Eu positive anomaly in hydrothermal fluid respectively. Then the hydrothermal fluid subsequently affects the garnet Eu anomaly character. As a result, the Eu anomaly of the garnet can be used to trace the salinity and oxygen fugacity of the hydrothermal fluids and the Eu enriched mineral dissolution or precipitation.

Analysis of Pore Properties of Favorable Shale Oil Reservoir of Chang-7 in Ordos Basin

WANG Xiaowen, GUAN Ping, LIANG Xiaowei, DING Xiaonan, YOU Yuan, ZHANG Chi, FENG Shengbin, ZHANG Jihua

2021, 57(3):  459-469.  DOI: 10.13209/j.0479-8023.2021.018

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Taking well YJ1 as the research object, the pore variety of shale oil reservoir of Chang-7 member in Ordos Basin is characterized qualitatively and quantitatively by using scanning electron microscope and high pressure mercury injection technology. The movable fluid in reservoir is researched by using nuclear magnetic resonance technology, and the main controlling factors affecting the difference of reservoir quality are discussed in detail. The results show that the lithology of high-quality shale oil reservoir in Chang-7 member of Ordos Basin is mainly fine-grained?very fine-grained lithic sandstone, and the sedimentary facies are mainly sandy clastic flow deposition. The reservoir pore types include primary intergranular pores and secondary dissolution pores, and the proportion of intergranular pores is more than that of dissolution pores. According to the type of pore variety, the reservoir can be divided into three types, among which the type I reservoir is the most high-quality reservoir in the study area, with good porosity and permeability. The mobility of reservoir fluid in the study area is mainly affected by the properties of pore variety, the mobile fluid is mainly stored in the macropores, and the effective pore volume is the factor restricting the mobility of fluid. The sand body caused by sandy clastic flow in the study area is a necessary condition for the formation of high-quality reservoir. The proportion of skeleton particles and cement in the rock is the key for the change of reservoir properties. When the skeleton particles increase and the cement content decreases, it is easy to form high-quality reservoir.

Analysis of Formation and Evolution of Salt Diapir in the Contractional Domain of Central Lower Congo Basin Based on Analogue and Discrete Element Modeling

CHENG Peng, LI Jianghai, LIU Zhiqiang

2021, 57(3):  470-480.  DOI: 10.13209/j.0479-8023.2021.025

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Based on the seismic profile, analogue modeling and discrete element modeling method were carried out to study the deep genetic mechanism of the gravity instability structure and evolution process of the salt diapirs in the contractional zone of central Lower Congo Basin in the passive continental margin of Angola in West Africa. The effect of salt diapir activity on the migration of the sedimentary center of the mini-basin between the diapirs was further studied. The results show that the evolution process of salt diapirs in the contractional domain of central Lower Congo Basin is related to the stress conditions. In the early stage, it was mainly controlled by the effect of gravity spreading, and in the later stage, it was controlled by the effect of squeezing. According to the comparison between the results of analogue modeling and discrete element modeling and the seismic sections, the evolution process of salt diapir can be divided into the following three stages: 1) The early stage, the extended reactive diapir stage; 2) The mid stage, the passive diapir stage; 3) The late stage, squeezed active diapir stage. The sedimentary center of the mini-basin between the salt diapirs migrated to the diapirs with strong activities during the same period.

Simulation Study on Nitrogen and Phosphorus Reycling Response of Changing Dissolved Oxygen Concentration in Lake Dianchi

HU Mengchen, ZHU Tao, JIANG Qingsong, ZOU Rui, WU Zhen, ZHANG Xiaoling, YE Rui, LIU Yong

2021, 57(3):  481-488.  DOI: 10.13209/j.0479-8023.2021.024

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A three-dimensional hydrodynamic-water quality model of Lake Dianchi was used to simulate the dynamic process of lake hydrodynamics and water quality, identify the characteristics of dissolved oxygen (Do) in the lake water. Combined with the setting of the external load reduction scenario, the effects of dissolved oxygen on the endogenous release of sediment and the cycle of nitrogen and phosphorus were explored. The results are conckyded. 1) The severe hypoxia in Lake Dianchi from June to September is caused by a combination of algae outbreaks and obstructed oxygen transport in the water. 2) Dissolved oxygen regulates the release of nitrogen and phosphorus nutrients in the sediment, and then significantly affects the concentration of nitrogen and phosphorus in the bottom water. 3) The improvement of the hypoxia condition at the bottom of the lake has high requirements on the reduction of external load. 4) The dissolved oxygen concentration at the phosphorus absorption-release equilibrium point of the sediment is about 3.3 mg/L, and the change in nitrogen concentration in Lake Dianchi is more susceptible to external load.

Ecological Waterway Assessment of Wuhan-Anqing Reach of the Yangtze River

LIU Nian, LI Tianhong, KUANG Shuya

2021, 57(3):  489-495.  DOI: 10.13209/j.0479-8023.2021.022

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Based on the principle of the harmonious relationship between navigation and river ecosystem protection, an evaluation indicator system for Wuhan-Anqing Reach in the middle-lower of the Yangtze River was constructed. With analytic hierarchy process (AHP) and the comprehensive evaluation index method considering the bucket effect of individual function to the whole system health, the ecological health condition of Wuhan-Anqing Reach in the year of 2018 was evaluated. The results showed that the waterway health index was 0.8145, indicating a fair level. The self-purification function graded excellent, and the navigation function, flood discharging function as well as landscape & entertainment function were good, while the ecological function was poor. The results suggested that ecological protection and rehabilitation should be strengthened in the process of future waterway regulation projects.

Impact of Successful Bid for Winter Olympics on Perceived Image in Beijing Tourism Destination

CONG Li, XU Linlin FANG Xiaoyu

2021, 57(3):  496-506.  DOI: 10.13209/j.0479-8023.2021.017

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This study conducts an empirical study on the impact of Beijing’s rights to host the Winter Olympics on its tourist destination image. In order to explore how winning the right to host the winter Olympics would affect the image of Beijing as a tourist destination, online travel notes of tourists to Beijing were collected on UGC platforms such as Mafengwo, Ctrip and Tuniu, and the content and emotion analysis of online text were conducted by using ROST CM 6.0 and ROST EA. The results show that: 1) after the success of the bid for the winter Olympics, Beijing’s image of the “winter Olympics” is more prominent, but not to a high degree. 2) The dimensions of the tourists’ perceived image of Beijing before and after the successful bid are different. Before the successful bid, the tourists’ perceived images of destinations are mainly reflected in the local atmosphere, attractions, transportation and Olympic venues, while after the successful bid, the tourists’ perceived images of destinations are mainly embodied in the local atmosphere, attractions, tourism services and international image. 3) Tourists’ emotions are mainly positive emotions, supplemented by neutral emotions, and the overall tends to neutralize.

Effect of Zeolite on Recovery of Anammox Bacteria Affected by Starvation

YU Daodao, SUN Jingqi, HUO Tangran, ZHAO Yunpeng, LIU Sitong

2021, 57(3):  507-516.  DOI: 10.13209/j.0479-8023.2021.011

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Zeolite has good ammonium absorption capacity and microbial carrier function. Anammox bacteria affected by starvation were activated in a reactor containing zeolite to study the effect of zeolite on the activity and structure of anammox bacteria after long-term starvation. The results showed that anammox bacteria recovered in the zeolite reactor and the control reactor (without zeolite addition) after 82 days of operation. The nitrogen removal efficiency of zeolite reactor began to lag behind that of the control reactor on the 59th day. On the 82nd day of operation, the nitrogen removal load (NRR) of zeolite reactor was 177.8 mgN/(L·d), significantly higher than that of the control reactor (154.3 mgN/(L·d)). At the same time, 16S rRNA high-throughput sequencing method was used to analyze the microbial composition and function of the microbial community in the reactor. It was found that adding zeolite carrier could increase the abundance of anammox bacteria Candidatus brocadia after recovery, and could better promote the recovery of anammox bacteria inhibited by hunger.

Co-benefits of Decarbonizing China’s Transport Sector in Energy Saving and Emission Reduction under 1.5- and 2-degree Targets in 2050

LU Pantao, HAN Yalong, DAI Hancheng

2021, 57(3):  517-528.  DOI: 10.13209/j.0479-8023.2021.012

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This study evaluates the energy structure change and co-benefits in air pollution improvement in the transportation sector of China in line with the 2oC and 1.5oC targets based on an energy system optimization model IMED|TEC. The results show that under 2oC and 1.5oC targets in 2050, the energy consumption would decrease by 12% and 33% compared to the reference scenario. The energy mix would shift from traditional petroleum to cleaner biomass and even electricity or hydrogen energy. Under the 2oC scenario, biomass energy would account for 35% of the total energy consumption, whereas under 1.5oC scenario, hydrogen and electricity would account for about 67% of total energy consumption. Decarbonization of China’s transportation sector can bring significant air quality improvement. Under the 2oC scenario, CO2 emissions will be reduced by 38% in 2050, associated with reductions of NO_x, SO₂ and PM_2.5 emissions by 35%, 34% and 38%, respectively. Under the 1.5oC scenario, the amount of pollutant emission reduction would be twice that at 2oC. However, emissions reduction rates would be quite limited for the aviation and waterway transportation sectors.

Thermophilic Cyanobacteria PKUAC-E542 Phycocyanin Heat Resistance and Effects of Different Light Conditions on Its Accumulation

LI Liheng, LIANG Yuanmei, LI Meijin, CHEN Pengyu, XIAO Meng, CUI Yixuan, Maurycy Daroch

2021, 57(3):  529-535.  DOI: 10.13209/j.0479-8023.2021.029

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This paper studied the heat resistance of phycocyanin and the accumulation of phycocyanin under different light conditions in thermophilic cyanobacteria. With 30°C, 40°C, 50°C, 60°C, 65°C, 70°C, 80°C, 90°C as the experimental group, 25°C and 4°C as the control group, the placement time was set to 5 hours and 14 days. Alignments of both chain α and β were conducted to figure out the heat resistant mechanism. PKUAC-SCTE542 was cultured under different photoperiods and different combinations of light sources, and its growth and phycocyanin content were studied to explore the light conditions which were suitable for phycocyanin production. Shaking incubators with narrow band light at following wavelengths: white (400–800 nm), red (654 nm), green (511 nm), and blue (454 nm), photoperiods of 8L/16D, 12L/12D, and 16L/8D, were tested. Dry weight and content of extracted phycocyanin were measured. PKUAC-SCTE542 phycocyanin kept stable at 65°C environments, and still maintained 60% activity after being placed at 60°C for 14 days. Under the conditions of red light and photoperiod of 8L/16D, the yield of phycocyanin was the highest; while the productivity of phycocyanin was the highest when red light and photoperiod of 16L/8D were set. In result, PKUAC-SCTE542 showed great heat resistance ability in this research. With light screening done, the phycocyanin yield increased by nearly 100 mg/gDCW.

Spatio-Temporal Dynamic Characteristics of Coupling and Coordination of Urbanization System: Case Study in the Coastal Zone of East China Sea

XU Nuanyin, LI Zhijian, ZENG Hui

2021, 57(3):  536-544.  DOI: 10.13209/j.0479-8023.2021.030

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Taking 11 cities in the coastal zone of East China Sea as the study area, the dynamic changes and correlations of the coupling and coordination of urbanization systems from 1978 to 2018 were explored based on the coupling coordination measurement model and gray correlation model. The results showed that the coupling and coordination of urbanization system in the study area exhibited a temporal phase and a spatial local high-value agglomeration. The characteristics of temporal phase were mainly manifested in urbanization speed, urbanization focus and urbanization balance. In 1978–2007, the urbanization level of each case city improved rapidly. The focus of urbanization was the optimization of industrial structure and the economic improvement, which were also the first to enter the coordinated development period with the urbanization rate. The coupling and coordination degree of urbanization system was significantly affected by a single key factor. In 2008–2018, the growth rate of urbanization tended to be flat, and the focus of urbanization began to shift to the improvement of the quality of development with “people”. The coupling and coordination between the two attributes of people’s livelihood quality and public service and the urbanization rate have been rapidly improved. Cities such as Shanghai and Xiamen, which have higher levels of urbanization, have entered the period of coordination and advanced coordination. The coupling and coordination of urbanization system was affected by multiple factors. The spatial local high-value agglomeration means that the coupling and coordination of urbanization system presented a development model with Shanghai, Ningbo, Fuzhou and Xiamen as the poles.

Influence of Propionate on Performance and Community Structure of an Anammox Reactor

ZHANG Liyu, QIAO Xuejiao, YU Ke

2021, 57(3):  545-555.  DOI: 10.13209/j.0479-8023.2021.031

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In order to study the long-term influence of organic carbon on performance and community structure of an Anammox reactor, propionate was amended stepwise into an enriched Anammox reactor to investigate the dynamic change of the structure and function of the community. The results suggested that nitrogen removal process was mainly achieved by Candidatus Brocadia. Carbon and nitrogen were simultaneously removed by the growth of heterotrophic bacteria under 100 mg/L propionate, while total nitrogen removal efficiency reached 91.9%. A suppression of growth of Candidatus Brocadia and a significant reduction of total nitrogen removal were observed at the present of 200 mg/L propionate. The relative abundance of Candidatus Brocadia and total nitrogen removal efficiency decreased to 41.2% and 78.8% respectively. After propionate concentration recovered to 0 mg/L, the nitrogen removal efficiency of the reactor improved to 86.8% and the abundance of Candidatus Brocadia was recovered to 54.0%. However, the community diversity decreased and the microbial composition at genus level changed a lot.

Characteristics of Rural Households’ Livelihood Capital and Its Impact on Life Satisfaction: Evidence from a Nationwide Survey in 25 Counties of 13 Provinces, China

LU Zhiqiang, CAO Guangzhong, LI Guicai

2021, 57(3):  556-564.  DOI: 10.13209/j.0479-8023.2021.026

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Based on a rural survey in 25 counties of 13 provinces in China, this paper establishes a measurement index system for livelihood capital and analyzes characteristics of rural households’ livelihood capital. The ordinal multi-class logistic regression model is adopted to explore the impact of rural households’ livelihood capital on life satisfaction. The following results are concluded. 1) Financial capital, human capital, social capital and physical capital are main components of rural households’ livelihood capital in China. The proportion of natural capital is relatively low, but it still has an irreplaceable role in safeguarding. 2) Rural households' livelihood capital has a certain spatial heterogeneity. The financial, human, social and physical capital of rural households in the eastern region is higher than that in the central and western regions, while the natural capital of rural households in the western region is higher than that in the central and eastern regions. 3) The increase in various types of livelihood capital does not necessarily improve the rural households’ life satisfaction. The increase in physical, financial or social capital is conducive to improving rural households’ life satisfaction, while human capital may have a negative impact. 4) The degree or direction of the impact of livelihood capital on rural households’ life satisfaction varies in different regions. The type of livelihood capital that affects rural households’ life satisfaction should be analyzed according to local conditions, so as to effectively improve rural households’ life satisfaction.

Urbanization Effects on Mammal Richness: A Case Study of Yangtze River Delta Urban Agglomeration

LIN Ping

2021, 57(3):  565-574.  DOI: 10.13209/j.0479-8023.2021.036

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Taking the fraction of impervious surface area as a quantitative indicator of urbanization intensity (UI), using the global mammal richness girds data set and combined with climatic variables and habitat characteristics, this paper studied the spatial distribution pattern of mammal richness along the urban-rural gradient in Yangtze River Delta urban agglomeration. The contribution of urbanization and background climate were analyzed by comparing the richness distribution pattern and driving forces of Yangtze River Delta urban agglomeration and the geographic region (East China) where it located. The results were as follows. 1) There was a horizontal “S” distribution pattern of mammal richness along the urban-rural gradient at both spatial scales. 2) In background geographic region, climatic variables (e.g, annual precipitation and min temperature of coldest month) played a dominant role in richness distribution (R²= 88.2%). 3) There was a negative correlation between UI and richness in East China while a weakly positive correlation in Yangtze River Delta (P<0.001); woodland had positive impacts on richness, while arable land had negtive impacts. The urbanization effects on mammal richness were more pronounced in Yangtze River Delta. Future research should pay more attention to how to disentangle the impacts of urbanization from background climate on biodiversity.

Research on Flood Risk Assessment of Floodplains from Huayuankou to Aishan Section in the Lower Yellow River

SUN Yuhang, CHENG Shupeng, ZHANG Qi, DU Pengju, LI Zhenshan, ZHAO Zhijie

2021, 57(3):  575-586.  DOI: 10.13209/j.0479-8023.2021.027

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The Delft3D model was used to simulate the flooding process on floodplains of the Lower Yellow River, and the flood disaster parameters such as flooding range and flooding depth were statistically calculated from the model. The process of giving the flood risk’s spatial distribution of the plains includes dividing the hazard-vulnerability units and calculating the hazard and vulnerability of each unit according to the topography and flood-control measures. The United Nations risk assessment index system is used to give out the spatial distribution of the flood risk for each inundation unit. The results show that the relationship between flood risk and flood scenarios response across the study area can be divided into three categories. About 50% of the plain are under “simultaneous flooding and risks”, which means the flood risk level generally varies with the flood scenario. 39.7% of the plains own the trait of “low flooding frequency leads to giant risks”, and for the unit of this category basically has the extreme risk even for the 10-year frequency floods. 11.67% of the plain are stable at a relatively low risk situation, and the flood risk is not affected by the magnitude of the flood, which is classified as “stable low risks”. In order to prevent the flood risk of the Lower Yellow River, the flooding unit of “low flooding frequency leads to giant risks” mainly distributed in Gaocun to Aishan section should give a priority to take the action, and the flood situation of once every ten years or even once every five years should be taken as the reference basis for building flood prevention measures.

Photocatalytic Degradation of Ciprofloxacin by Magnetic CoFe₂O₄/g-C₃N₄ Nanocomposites

TAO Huchun, DENG Liping, ZHANG Lijuan, DING Lingyun

2021, 57(3):  587-594.  DOI: 10.13209/j.0479-8023.2021.037

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Magnetic CoFe₂O₄/g-C₃N₄ nanocomposites were synthesized and its surface morphology, element and chemical composition, specific surface area, functional group characteristics and crystal structure were characterized. Targeting at quinolone antibiotics of ciprofloxacin (CIP), the photo-catalytic degradation of CIP by CoFe₂O₄/g-C₃N₄ nanocomposites was investigated at different calcination temperature (300^oC, 400^oC and 500^oC) and composite ratio (CoFe₂O₄:g-C₃N₄=10%, 20% and 40%, w/w). Under optimal synthesis and operating conditions, a maximum degradation efficiency of 75.1 ± 0.1% was achieved for 0.9 g/L CoFe₂O₄/g-C₃N₄ with 10 mg/L CIP (pH=6.6) within 120 min. With an external magnetic field, the CoFe₂O₄/g-C₃N₄ nanocomposites were easily and rapidly recycled, remaining >90% of the initial efficacy after 5 cycles and showing a considerable stability. Fluorescence spectra revealed a significant decrease in electron-hole recombination rates under light radiation, which contributed greatly to the increase of photo-degradation efficacy of CIP by CoFe₂O₄/g-C₃N₄ nanocomposites.