[an error occurred while processing this directive]

Table of Content

    20 May 2022, Volume 58 Issue 3
    Recognition of Complex Entities in Weapons and Equipment Field
    YOU Xindong, GE Haojie, HAN Junmei, LI Yuxian, LÜ Xueqiang
    2022, 58(3):  391-404.  DOI: 10.13209/j.0479-8023.2021.118
    Asbtract ( )   HTML   PDF (3577KB) ( )  
    Related Articles | Metrics
    Aiming at the characteristics of complex entities in weapons and equipment field, a complex named entity recognition method is proposed which integrates multi-features and mounts the domain knowledge of weapons and equipment. First, we use the BERT model to pre-train on the weapon equipment field data to obtain the data vector, and use the Word2Vec model to learn context features of Zhengma, Wubi, Pinyin, and strokes to obtain the feature vector. Then the data vector and the feature vector are fused, the Bi-LSTM model is used for encoding, and the CRF decoder is used to obtain the tag sequence. Finally, the detection of complex entities on the label sequence is triggered to complete the recognition of complex named entities. In the experiments, we use the data collected from Global Military Network as the corpus, and analyze the recognition effect of different feature combinations and neural network models. A calculation method suitable for evaluating the recognition results of complex named entities is also proposed. The experimental results show that the F1-value of the proposed method for recognizing complex named entities of weapons and equipment with domain knowledge and fusion of multifeatures reaches 95.37%, which outperforms the existing methods.
    Study on the Irradiation Characteristics of Laser-Accelerated Proton Beam on SiC
    ZHOU Danqing, LI Dongyu, CHEN Yi, LI Yue, YANG Tong, CHENG Hao, WU Minjian, LI Yuze, YAN Yang, XIA Yadong, LIN Chen, YAN Xueqing, ZHAO Ziqiang
    2022, 58(3):  405-411.  DOI: 10.13209/j.0479-8023.2022.006
    Asbtract ( )   HTML   PDF (3552KB) ( )  
    Related Articles | Metrics
    By irradiating the nuclear material SiC, the characteristics of continuous wide energy spectrum, short pulse and high instantaneous current intensity of the laser-accelerated proton beam have been characterized. The SiC samples were placed at a distance of 4 cm from the target. The 300 shots proton beams were irradiated with a continuous wide energy spectrum proton beam of 1–4.5 MeV, which satisfied the exponential energy spectrum distribution. The surface and cross-section Raman characterizations showed that the intensity of the SiC scattering peaks after irradiation were reduced. The overall trend of Raman cross-section measurement was consistent with the depth of the distribution of energy loss by SRIM simulation. Thus, the experimental characterization of laseraccelerated proton beam with continuous energy distribution was realized. In addition, experiments showed that the short pulse characteristic of the laser-accelerated proton beam could produce a relatively high instantaneous beam current density on the SiC surface. The ultra-fast wide energy spectrum irradiation provides a possibility in simulated reactor neutron irradiation.
    Research on Relations between Atmospheric Mixing Layer Heights and Fine Particle Concentrations with Lidar Measurements
    SANG Yueyang, CHU Yiqi, LIU Zhe, REN Jingjing, TIAN Xiaoqing, WANG Qixi, LI Chengcai
    2022, 58(3):  412-420.  DOI: 10.13209/j.0479-8023.2022.022
    Asbtract ( )   HTML   PDF (1259KB) ( )  
    Related Articles | Metrics
    Based on the observations of a micro-pulse lidar in Beijing, the MLH is retrieved by using the artificial assistance algorithm during the day from 2016 to 2019. Then the seasonal and diurnal variations of MLH and its relationship with PM2.5 mass concentration are analyzed. The results show that the MLH shows obvious seasonal and diurnal changes, and the daily averaged MLH is significantly higher in spring than that in other seasons. The daily maximum MLH height in every year occurs in May of the year. The variation trend of the MLH is opposite to the concentration of PM2.5 from 08:00 am to 03:00 pm. Through linear fitting of the data, it is shown that the negative correlation is stronger when the ventilation index and wind speed are induced. When considering the influence of wind direction, the MLH has a stronger negative correlation with PM2.5 in the case of southwesterly wind. In addition, after weather classification, the correlation between PM2.5 and the MLH in each same weather group can be significantly improved.
    A Case Study on Organization Features of Successive Mesoscale Convective Systems in the Environment of Northeast China Cold Vortex
    ZHU Yuning, MENG Zhiyong, LEI Lei, YI Xiaoyuan, LIU Hongjun, LI Sa
    2022, 58(3):  421-433.  DOI: 10.13209/j.0479-8023.2022.033
    Asbtract ( )   HTML   PDF (8390KB) ( )  
    Related Articles | Metrics
    The evolution of the organizations and the synoptic features of four successive mesoscale convective systems (MCSs) in the Beijing-Tianjin area under the background of the Northeast China cold vortex (NCCV) during 21 hours from 0400 UTC to 2400 UTC on July 22, 2009 was examined by using radar, surface observations, sounding data and ERA5 reanalysis data. The results showed that the convections in the four processes had different organizational patterns owing to the complex interaction among the shallow trough in the northwesterly flow in the middle troposphere to the southwest of the NCCV, the associated lower troposphere trough and cyclonic vortex, the southwesterly warm and moist flow, and cold pools under the background of long-lasting northwesterly flow to the southwest of the NCCV. The first process was triggered in north Hebei Province by the frontogenesis caused by a shallow trough on the west to the NCCV. A southwest-northeast oriented weak convective line was formed with the cell in north Beijing and developed the fastest and strongest. It evolved into a supercell and a bow echo later on. It produced cold pool which lifted the warm and humid air from the southwest producing series cells to a northwest-southeast oriented backbuilding pattern across the Beijing-Tianjin area. The second process was triggered by the cold pool of the first process on the south of Beijing and formed a supercell. The westward outflow of new convection of the first process made the supercell evolve into a southwest-northeast oriented backbuilding convective line. In the third process, a vortex in the lower troposphere formed corresponding to the strengthening of the trough to the south of the NCCV. The northerly wind on the west of the vortex in the lower troposphere converged with the southerly wind on the northwest side of the high-pressure ridge in the lower troposphere, producing multiple northwest-southeast oriented linear backbuilding convective lines. The echo training of these backbuilding convective lines caused heavy rainfall in Tianjin.. The fourth process started with two linear convections triggered respectively by the frontogenesis generated by another shallow mid-troposphere trough on the westsouth to the NCCV and the shear line generated by the NCCV in north Tianjin. The two linear convections merged into one due to the shear line in the lower troposphere with the southern part evolving into a bow echo. Some of the bow echoes had bow and arrow structure in the evolution of the four processes.
    Experimental Research of Methane Flux Measurement by the Relaxed Eddy Accumulation Method
    GE Hongxing, WEI Zhuorui, ZHANG Hongsheng, KANG Ling
    2022, 58(3):  434-442.  DOI: 10.13209/j.0479-8023.2022.021
    Asbtract ( )   HTML   PDF (11630KB) ( )  
    Related Articles | Metrics
    Based on the data collected at the Atmospheric Turbulence and Atmospheric Environment Experimental Station in east China from November 2015 to November 2016, the methane flux over farmland was estimated using the relaxed eddy accumulation (REA) method. During the experiment, the empirical coefficients b of various scalars including temperature, water vapor, carbon dioxide and methane for the REA method were 0.59, 0.59, 0.59 and 0.58, respectively. The median of b decreased with the increase of the normalized sampling threshold HREA. The minimum dispersion of b for each scalar was reached with HREA=0.8. The methane flux obtained by the REA method with T as the proxy scalar was highly consistent with the flux obtained by the EC method, showing that the REA method was suitable for measuring methane flux.
    Retrieval of Ground PM2.5 Concentrations in Eastern China Using Data from Himawari-8 Satellite
    LIU Zhe, ZHAO Weilun, TIAN Xiaoqing, SANG Yueyang, QU Yonglin, REN Jingjing, LI Chengcai
    2022, 58(3):  443-452.  DOI: 10.13209/j.0479-8023.2022.032
    Asbtract ( )   HTML   PDF (2110KB) ( )  
    Related Articles | Metrics
    In order to retrieve the large-scale ground PM2.5 concentration distribution in eastern China, a model was built using machine learning. The model used the top-of-atmosphere reflectance data of the Himawari-8 geostationary satellite in 2019 and the meteorological data of the European Center as the input data, and the ground PM2.5 concentration was the output data. Validation results showed that the model had high accuracy on different time scales in eastern China. The ten-fold cross-validation of the model had a correlation coefficient of 0.82 and a root-mean-square error of 20.11 μg/m3 for hourly PM2.5 concentration inversion. The hourly satellite-meteorological grid data throughout the year of 2019 were input to the model, and the corresponding PM2.5 grid data for the eastern China obtained. Good results were achieved for the PM2.5 grid data after analyzing the seasonal variation and spatial distribution of PM2.5 concentration over eastern China.
    Geochronological and Geochemical Characteristics of the Middle Permian Rhyolite and Its Geological Implications in Siziwang Banner, Inner Mongolia
    WANG Qi, TANG Jianzhou, CHENG Jian, DUAN Tiejun, DING Cong, ZHANG Huaihui, MENG Yunxi, ZHANG Zhicheng
    2022, 58(3):  453-468.  DOI: 10.13209/j.0479-8023.2022.030
    Asbtract ( )   HTML   PDF (37061KB) ( )  
    Related Articles | Metrics
    A set of rhyolite strata, classified as middle-lower Jurassic series in geological mapping, are exposed in Siziwang Banner that across the border between North China Craton and Inner Mongolia-Daxinganling Orogenic Belt. Petrology, geochemistry, zircon U-Pb geochronology and Hf isotope analysis were performed to investigate the petrogenesis and geodynamic significance of the rhyolite strata. The weighted mean 206Pb/238U ages from the rhyolite and rhyolite porphyry by LA-ICP-MS zircon U-Pb dating are 262±2 Ma to 261±2 Ma, suggesting to the late Middle Permian. The volcanic rocks in Siziwang Banner belong to the high-K calc-alkaline series and shoshonite series, which are characterized by high silicon, alkali, and aluminum, depleted calcium and magnesium. The total amount of rare earth element values is high, and the chondrite normalized REE patterns are enriched in LREE relative to HREE, with moderate to strong negative Eu anomalies, enrichment of large ion lithophile elements Rb, Th and LREE, and depletion of Nb, Ta, Sr and Ba. The volcanic rocks have obviously negative Hf values (-25.97~-11.94), indicating that they may be derived from the partial melting of the ancient crust. The volcanic rocks have high-silica rhyolite characteristics, suggesting that they have undergone significant fractional crystallization and are related to the heating of deep mantle derived magma. The geochemical features and various tectonic discrimination diagrams of the volcanic rocks suggest that the volcanic rocks in Siziwang Banner area were formed in a post-collisional extensional setting.
    Paleomagnetic Inclination Shallowing in Badong Formation Red Beds, Middle Triassic of South China Block
    HAN Lu, HUANG Baochun, ZHAO Qian, XUE Yi, LI Nengtao, Umar Farooq Jadoon
    2022, 58(3):  469-480.  DOI: 10.13209/j.0479-8023.2022.031
    Asbtract ( )   HTML   PDF (1169KB) ( )  
    Related Articles | Metrics
    Paleomagnetic and rock magnetic studies are conducted on Middle Triassic Badong Formation red beds from the South China Block (SCB). The anisotropy of high-field isothermal remanent magnetization (hf-AIR) method indicates that the characteristic remanent magnetization (ChRM) is significantly affected by inclination shallowing with a flattening factor f = 0.63. Rock magnetic analysis indicates that hematite is the main magnetic carrier with a subordinate contribution from magnetite. Anisotropy of magnetic susceptibility (AMS) and hf-AIR results both show a typical depositional fabrics without significant distortion from tectonic stress. The ChRM, carried by detrital hematite, has a unique negative polarity and passes the fold test at the 95% confidence level. The ChRM yields a common mean direction with that previously reported from the same section. The ChRM yields a tilt-corrected mean direction of Ds = 222.1°, Is = ?27.2° (α95 = 8.7°) and a corresponding paleomagnetic pole at 48.1°N, 215.5°E (A95 = 8.4°). Combined with high quality published data (Q≥5) for the Middle Triassic, the mean paleomagnetic pole for the SCB is corrected to 48.5°N, 207.6°E with A95 = 10.7° by using a flattening factor f = 0.63. Comparing this inclination shallowing-corrected mean paleomagnetic pole with Early Triassic pole for the North China Block, which has also inclination shallowing-corrected by the hf-AIR method, it shows that paleolatitudes of these two blocks at their eastern reference points are exactly compatible. This further confirms that the South and North China blocks experienced a scissors-like rotational collision during the Mesozoic times, as proposed by previous researches. 
    Discussion about Near Trench Triggering during 2012 Mw 7.2 Indian-Ocean Strike-Slip Earthquake
    JIA Bo, YUE Han
    2022, 58(3):  481-487.  DOI: 10.13209/j.0479-8023.2022.023
    Asbtract ( )   HTML   PDF (1038KB) ( )  
    Related Articles | Metrics
    Whether the aftershocks near the trench were triggered by 2012 Indian Ocean Mw 7.2 earthquake was discussed by using teleseismic P-wave records. According to the assumption of the direct and indirect trigger mechanism of regional water waves, the line-source model and the two-point source model were proposed. The inversion results show that the line-source model based on the direct trigger mechanism was better than the two-point model on the waveform fitting, and the aftershocks near the trench were not triggered during 2012 Indian Ocean earthquake.
    Residents’ Place Attachment from the Perspective of Lifeworld in Chinese Historic and Cultural Areas: A Case Study in Qianjin Street in Xinjiang
    XIANG Lanlin, YE Yafei, PAN Jingdong, WANG Zhenlong
    2022, 58(3):  488-502.  DOI: 10.13209/j.0479-8023.2022.010
    Asbtract ( )   HTML   PDF (5540KB) ( )  
    Related Articles | Metrics
    To explore the dimensions and structure of residents’ place attachment, this paper takes Qianjin Street district in Yining City of Xinjiang Uygur Autonomous Region as the case to conduct an empirical research from the residents’ perspective, through quantitative analysis combined with qualitative interviews and Mapping method. The principal component analysis of place attachment obtains five principal components of 20 questions: emotional bond, social bond, environmental perception, life experience and work connection. The overall structure of the scale has good stability and discrimination. Furthermore, combined with qualitative interviews and cognitive map analysis of residents, a Lifeworld-Place attachment model composed of emotional bond, social bond and daily life is obtained. The combination of the model with attributes in the study of cultural landscape heritage can strengthen the public participation and dynamic characteristics in historical districts’ conservation.
    Seasonal Dynamics of Activities, Temperature Sensitivities and Vector Characteristics of Extracellular Enzymes in Rhizosphere and Bulk Soils of Two Temperate Forests in Mt. Dongling, Beijing 
    FU Liangchen, DING Zongju, TANG Mao, ZENG Hui, ZHU Biao
    2022, 58(3):  503-516.  DOI: 10.13209/j.0479-8023.2022.035
    Asbtract ( )   HTML   PDF (1706KB) ( )  
    Related Articles | Metrics
    Taking Betula platyphylla forest and Quercus wutaishanica forest, two main vegetation types in Mt. Dongling, Beijing as study object, we sampled paired rhizosphere and bulk soils in spring (May), summer (July), autumn (September) and winter (December) in 2017, and measured soil physiochemical properties, microbial biomass, functional traits of plant leaves and fine roots, activities of three hydrolases (BG, NAG, AP) and two oxidases (POX, PER) as well as their temperature sensitivities and vector characteristics. The results showed that EEA, Q10 and vector angle of soil in both forests had significant seasonal variation trends, and the seasonal variation trends of hydrolase activity and temperature sensitivity were opposite to those of oxidase. EEA, Q10 and vector characteristics of rhizosphere soil and bulk soil were different, but their seasonal variation trends were similar. Temperature was an important driving factor of the seasonal dynamics of soil EEA, Q10, and vector characteristics. Soil pH, soil nutrient content, leaf nutrient content, fine root biomass and fine root density showed significant effects on soil EEA, Q10, and vector characteristics.
    Effects of Nitrogen Addition on Soil Organic Carbon and Soil Respiration in Subtropical Evergreen Broad-Leaved Forest
    SU Zirui, ZENG Faxu, ZHENG Chengyang
    2022, 58(3):  517-525.  DOI: 10.13209/j.0479-8023.2022.017
    Asbtract ( )   HTML   PDF (1457KB) ( )  
    Related Articles | Metrics
    In order to simulate changes in natural nitrogen deposition and explore the effects of nitrogen addition on soil organic carbon and soil respiration, four treatments (CK (control), N50 (50 kg/(hm2·a) of N), N100 (100 kg/(hm2·a) of N) and N150 (150 kg/(hm2·a) of N)) were conducted in a subtropical evergreen broad-leaved forest in Wuyi mountain, Fujian Province. The results showed that the effect of nitrogen addition on the TOC of the surface soil (0–20 cm) was not significant, and the effect on the content of its different components is different. Compared to the CK, N100 and N150 significantly increased the soil POC content by 110.7% and 147.9% (p1 = 0.024, p2 <0.001). The content of soil MAOC tended to decrease with the increase of nitrogen addition, but the difference was not significant. The annual dynamic of soil respiration rate was unimodal distribution, and nitrogen treatments had different effects on soil respiration in different observation time. Based on fitting equations of soil respiration rate and soil temperature, the annual average carbon efflux of soil respiration in CK, N50, N100, and N150 plots from 2018 to 2020 were 1205.31, 1191.56, 1287.56 and 1128.61 g C/m2, respectively. Compared to the CK, annual average carbon efflux of soil respiration did not change significantly in N50, significantly increased by 6.82% in N100 (p<0.001), and significantly reduced by 6.8% in N150 (p<0.001), which meaned that N100 promoted annual carbon efflux from soil respiration, while N150 had an inhibitory effect on it.
    Metabolic Influence of Mercury Contamination on Bacterial Mercury Methylation by Geobacter sulfurreducens PCA
    TAO Huchun, QIAN Lu, ZHANG Lijuan, DING Lingyun, FANG Fang, DAI Maifan, WEI Ruqian
    2022, 58(3):  526-536.  DOI: 10.13209/j.0479-8023.2022.036
    Asbtract ( )   HTML   PDF (3937KB) ( )  
    Related Articles | Metrics
    Metabolomics, a rising omics approach, was employed to screen out cellular significantly differential metabolites and analyze related metabolic pathways in bacterial Hg-methylating process. Under the stress of Hg(II) at environmentally relevant concentrations (0?100 μg/L), the adsorbed/assimilated Hg(II) was utilized by Hg-methylator of Geobacter sulfurreducens PCA to reduce and methylate Hg(II). The highest efficiency of 3.09%± 0.16% was achieved for bacterial Hg-methylation upon exposure to 10 μg/L Hg(II). Metabolomics data showed that carbohydrate metabolism, amino acid metabolism and nucleotide metabolism were disturbed by Hg(II) stress in the PCA cells. To withstand the stress of Hg(II), G. sulfurreducens PCA increased energy demand for Hg methylation and DNA repair. 
    Study on Characteristics of Transpiration, Cooling Effect and Carbon-Reduction Effect of Ficus concinna, a Native Tree Species in Subtropical Cities
    DING Junjie, QIN Longjun, TAN Shenglin, YU Xiaohui, ZOU Zhendong, QIU Guoyu, YAN Chunhua
    2022, 58(3):  537-545.  DOI: 10.13209/j.0479-8023.2022.040
    Asbtract ( )   HTML   PDF (1427KB) ( )  
    Related Articles | Metrics
    Based on the transpiration transfer coefficient (hat), the cooling potential of several typical subtropical urban vegetations was evaluated. A Ficus concinna was continuously observed to quantitatively study its characteristics of transpiration, cooling effect and carbon-reduction effect. The results showed that 1) among several typical vegetations in the study area, Ficus concinna, as a native tree species, showed the strongest cooling potential in the same environment. 2) The average daily transpiration volume of Ficus concinna was 32.48 kg per tree, which was generally high in summer and autumn and low in spring and winter. At the same time, Ficus concinna could effectively alleviate the heat island effect, especially at night in summer when the heat island effect was severe, its cooling effect made the observation area no heat island state for 86% of the time. 3) The annual carbon emission reduction from the cooling effect of individual Ficus concinna reached 1442.1 kg.
    Microwave Assisted Degradation of Perfluorooctanoic Acid by Hydroxylamine
    LIN Fang, LÜ Ming, YUE Linxia, XU Nan
    2022, 58(3):  546-552.  DOI: 10.13209/j.0479-8023.2022.026
    Asbtract ( )   HTML   PDF (563KB) ( )  
    Related Articles | Metrics
    Microwave assisted hydroxylamine technology was used to achieve rapid and efficient degradation of perfluorooctanoic acid (PFOA). The degradation efficiency of PFOA (50 mg/L) reached 82.22% after 6 min of reaction when the microwave power, hydroxylamine concentration, reaction temperature and pH were 1200 W, 1.0 mM, 200°C and 3.92, respectively. The reaction system was uniformly heated by microwave through the reactor wall, and the hydroxylamine in the reaction system selectively absorbed microwave energy under microwave conditions, resulting in “hot pot” effect, which promoted the generation of free radicals and improved the degradation efficiency. The free radical quenching experiments showed that superoxide radical (O2.–) was the main active group for hydroxylamine to degrade PFOA. The O2.– first attacked the carboxyl functional group (-COOH) in PFOA, resulting in the fracture of C―O bond and loss of the hydroxyl group (-OH). After losing -OH, the remainder was unstable and continued to fracture and lose CF2 step by step, and was finally degraded into F and CO2. Therefore, the PFOA degradation by microwave assisted hydroxylamine reduction provides a reference and theoretical basis for the treatment of emerging persistent organic pollutants. 
    Future Year Air Quality Attainment Prediction Method Based on Design Value and Relative Response Factor: A Case Study Focusing on Implementation Planning of the 14th Five-Year Plan in Sichuan Province 
    HUANG Ran, WANG Xinlu, WANG Cong, DU Yunsong, YAN Bo, ZHANG Wenxian, LUO Bin, ZHANG Wei, HU Yongtao
    2022, 58(3):  553-564.  DOI: 10.13209/j.0479-8023.2022.024
    Asbtract ( )   HTML   PDF (1519KB) ( )  
    Related Articles | Metrics
    A novel future year air quality attainment prediction method, which is based on the design value of air pollutant concentration and relative response factor (RRF), has been developed to predict pollutant concentration levels under different emission control scenarios. The method first conducts numerical simulations to evaluate the effect of annual meteorological differences among the recent five years on the concentrations of air pollutants. The “typical” year, of which the meteorological condition is the closest to the five-year average, is selected as the base year. The air quality is simulated with the meteorological field and emission scenarios of the base year as the input of model so as to reduce the influence of inter-annual differences in meteorological conditions on the prediction of future pollutant concentration levels. Then it applies the regional air quality model for multiple times to simulate the pollutant concentration levels with different emission inputs that represent base and control emission scenarios. Lastly, it multiplies the design value of pollutant concentrations with the RRF derived from the ratios between the simulated concentrations of the control and base scenarios, to predict the future pollutant levels and to conduct air quality attainment tests. The method is applied to conduct scenario predictions and air quality attainment tests for the cities in Sichuan Province by designing multiple virtual air pollutant emission control scenarios based on the relevant emission reduction policies. The air quality attainment prediction results under different control scenarios, which aim to accomplish the goals of the 14th Five-Year Plan on air quality, can be useful for refining the local implementation strategies for control of air pollution.
    Circulation Classification and Source Analysis of Summer Ozone Pollution in Chengdu
    SHI Wenbin, QU Kun, YAN Yu, QIU Peipei, WANG Xuesong, DONG Huabin
    2022, 58(3):  565-574.  DOI: 10.13209/j.0479-8023.2022.016
    Asbtract ( )   HTML   PDF (2726KB) ( )  
    Related Articles | Metrics
    In order to explore the impact of large-scale circulations on O3 pollution in Chengdu, based on the 700 hPa geopotential height field in the Sichuan Basin (SCB) and using the T-PCA method, the atmospheric circulations in the summer of 2015–2019 (June–August) were classified into five circulation patterns, and the characteristics of O3 pollution and O3 sources in Chengdu under different circulation patterns were identified. Among the five types of circulation patterns, the northeast-high pressure (NEH) pattern and the under-high pressure field (UNF) pattern generally led to higher air temperature, and lower humidity and cloud cover in the SCB. Air temperature change compared to the previous days showed an obvious increasing trend in the SCB under the UNF pattern, kept stable under the NEH pattern, and indicated cooling effects with varying intensities under the other three circulation patterns (the southeast-high pressure pattern, the northwest-low pressure pattern and the northwest-high pressure pattern). The meteorological conditions under NEH and UNF were more conducive to the photochemical production of O3 in the SCB. During the study period, O3 concentrations and the percentages of over-standard days of O3 in Chengdu under NEH and UNF were significantly higher than those under the other three circulation patterns, and thus NEH and UNF were the main circulation patterns that were related to O3 pollution in summer. Months with more severe O3 pollution in Chengdu tended to have higher proportion of days under the NEH and UNF patterns. The simulation studies of O3 sources in Chengdu in summer suggested that O3 was mainly derived from the SCB (55.0%), with local contribution of Chengdu (31.6%), and other important contributing cities including Deyang (5.4%), Chongqing (4.0%), Ziyang (3.9%) and Meishan (2.2%). However, O3 sources in Chengdu under different circulation patterns showed different characteristics. Under the NEH pattern, O3 transport within the Chengdu Plain had notable impact on O3 pollution in Chengdu, with a significant increasing contribution from Deyang (14.9%). By contrast, under the UNF pattern, O3 pollution in Chengdu became more localized, with nearly half (46.8%) of O3 contributed by local emissions. 
    Distribution of Per- and Polyfluoroalkyl Substances (PFASs) in Lower Reach of Yellow River, China
    LÜ Ming, ZHU Youchang, PAN Baozhu, XU Nan
    2022, 58(3):  575-586.  DOI: 10.13209/j.0479-8023.2022.025
    Asbtract ( )   HTML   PDF (2572KB) ( )  
    Related Articles | Metrics
    Fifty PFASs were measured in water and sediment samples collected from the lower reach of Yellow River in spring and autumn to understand their distribution and ecological risk. The results indicated that the total concentrations of PFASs in water ranged from 29.83–54.44 ng/L in spring and 16.18–57.81 ng/L in autumn, while the total contents in sediment ranged from 18.12–36.16 ng/g in spring and 13.01–36.78 ng/g in autumn. Perfluoroalkyl carboxylic acids (PFCAs), perfluoroalkane sulfonic acids (PFSAs) and n:2 fluorotelomer sulfonic acids (n:2 FTSs) were the three dominant types of PFASs in both seasons, and n:2 FTSs, as emerging PFASs, were detected with high concentrations in both water and sediment. Short-chain PFCAs were the main substitutes of perfluorooctanoic acid (PFOA) in water and sediment, while hexafluoropropylene oxide dimer acid (HFPO-DA) presented a higher substitution trend to PFOA in sediment; the main substitute of perfluorooctane sulfonic acid (PFOS) in water and sediment was 6:2 FTS. The results of risk quotient analysis showed that the PFASs target compounds in water posed no ecological risks to aquatic environment.