Chemical characterization and source identification of PM2.5 in Luoyang after the clean air actions

Luoyang is a typical heavy industrial city in China, with a coal-dominated energy structure and serious air pollution. Following the implementation of the clean air actions, the physicochemical characteristics and sources of PM_2.5 have changed. A comprehensive study of PM_2.5 was conducted from October 16, 2019 to January 23, 2020 to evaluate the effectiveness of previous control measures and further to provide theory basis for more effective policies in the future. Results showed that the aerosol pollution in Luoyang in autumn and winter is still serious with the average concentration of 91.1 μg/m³, although a large reduction (46.9%) since 2014. With the contribution of nitrate increased from 12.5% to 25.1% and sulfate decreased from 16.7% to 11.2%, aerosol pollution has changed from sulfate-dominate to nitrate-dominate. High NO₃⁻/SO₄²⁻ ratio and the increasing of NO₃⁻/SO₄²⁻ ratio with the aggravation of pollution indicating vehicle exhaust playing an increasingly important role in PM_2.5 pollution in Luoyang, especially in the haze processes. Secondary inorganic ions contributed significantly to the enhancement of PM_2.5 during the pollution period. The high value of Cl⁻/Na⁺ and EC concentration indicate coal combustion in Luoyang is still serious. The top three contributor sources were secondary inorganic aerosols (33.3%), coal combustion (13.6%), and industrial emissions (13.4%). Close-range transport from the western and northeastern directions were more important factors in air pollution in Luoyang during the sampling period. It is necessary to strengthen the control of coal combustion and reduce vehicle emissions in future policies.     

Significant contribution of secondary particulate matter to recurrent air pollution: Evidence from in situ observation in the most polluted city of Fen-Wei Plain of China

Particulate matter (PM) pollution in high emission regions will affect air quality, human health and climate change on both local and regional scales, and thus attract worldwide attention. In this study, a comprehensive study on PM_2.5 and its chemical composition were performed in Yuncheng (the most polluted city of Fen-Wei Plain of China) from November 28, 2020 to January 24, 2021. The average concentration of PM_2.5 was 87.8 ± 52.0 μg/m³, which were apparently lower than those observed during the same periods of past five years, attributable to the clean air action plan implemented in this region. NO₃⁻ and organic carbon (OC) were the dominant particulate components, which on average contributed 22.6% and 16.5% to PM_2.5, respectively. The fractions of NO₃⁻, NH₄⁺, OC and trace metals increased while those of crustal materials and elemental carbon decreased with the degradation of PM_2.5 pollution. Six types of PM_2.5 sources were identified by the PMF model, including secondary inorganic aerosol (35.3%), coal combustion (28.7%), vehicular emission (20.7%), electroplating industry (8.6%), smelt industry (3.9%) and dust (2.8%). Locations of each identified source were pinpointed based on conditional probability function, potential source contribution function and concentration weighted trajectory, which showed that the geographical distribution of the sources of PM_2.5 roughly agreed with the areas of high emission. Overall, this study provides valuable information on atmospheric pollution and deems beneficial for policymakers to take informed action to sustainably improve air quality in highly polluted region.     

Characteristics of PM2.5 pollution in Beijing after the improvement of air quality

Following the implementation of the strictest clean air policies to date in Beijing, the physicochemical characteristics and sources of PM_2.5 have changed over the past few years. To improve pollution reduction policies and subsequent air quality further, it is necessary to explore the changes in PM_2.5 over time. In this study, over one year (2017–2018) field study based on filter sampling (TH-150C; Wuhan Tianhong, China) was conducted in Fengtai District, Beijing, revealed that the annual average PM_2.5 concentration (64.8 ± 43.1 μg/m³) was significantly lower than in previous years and the highest PM_2.5 concentration occurred in spring (84.4 ± 59.9 μg/m³). Secondary nitrate was the largest source and accounted for 25.7% of the measured PM_2.5. Vehicular emission, the second largest source (17.6%), deserves more attention when considering the increase in the number of motor vehicles and its contribution to gaseous pollutants. In addition, the contribution from coal combustion to PM_2.5 decreased significantly. During weekends, the contribution from EC and NO₃^? increased whereas the contributions from SO₄^2?, OM, and trace elements decreased, compared with weekdays. During the period of residential heating, PM_2.5 mass decreased by 23.1%, compared with non-heating period, while the contributions from coal combustion and vehicular emission, and related species increased. With the aggravation of pollution, the contribution of vehicular emission and secondary sulfate increased and then decreased, while the contribution of NO₃^? and secondary nitrate continued to increase, and accounted for 34.0% and 57.5% of the PM_2.5 during the heavily polluted days, respectively.     

Water-soluble matter in PM2.5 in a coastal city over China: Chemical components, optical properties, and source analysis

Although marine and terrestrial emissions simultaneously affect the formation of atmospheric fine particles in coastal areas, knowledge on the optical properties and sources of water-soluble matter in these areas is still scarce. In this work, taking Qingdao, China as a typical coastal location, the chemical composition of PM_2.5 during winter 2019 was analyzed. Excitation-emission matrix fluorescence spectroscopy was combined with parallel factor analysis model to explain the components of water-soluble atmospheric chromophores of PM_2.5. Our analysis indicated that NO₃⁻, NH₄⁺ and SO₄²⁻ ions accounted for 86.80% of the total ion mass, dominated by NO₃⁻. The ratio of [NO₃⁻]/[SO₄²⁻] was up to 2.42 ± 0.84, suggesting that mobile sources play an important role in local pollutants emission. The result of positive correlation between Abs₃₆₅ with K⁺ suggests that biomass burning is an important source of water-soluble organic compounds (WSOC). Six types of fluorophores (C1-C6), all humic-like substances, were identified in WSOC. Humification index, biological index and fluorescence index in winter were 1.66 ± 0.34, 0.51 ± 0.44 and 1.09 ± 0.78, respectively, indicating that WSOC in Qingdao were mainly terrestrial organic matters. Overall, although the study area is close to the ocean, the contribution of terrestrial sources to PM_2.5, especially vehicle exhaust and coal combustion, is still much higher than that of marine sources. Our study provides a more comprehensive understanding of chemical and optical properties of WSOC based on PM_2.5 in coastal areas, and may provide ground for improving local air quality.     

Seasonal variation characteristics of hydroxyl radical pollution and its potential formation mechanism during the daytime in Lanzhou

Hydroxyl free radicals (OH radicals) play the main role in atmospheric chemistry and their involving reactions are the dominant rate determining step in the formation of secondary fine particulate matter and in the removal of air pollutants from the atmosphere. In this paper, we studied the seasonal variation characteristics of OH radicals during the daytime in Lanzhou and explored the potential formation mechanism of high concentration OH radicals. We found that the OH radicals in four seasons was 2.7 × 10⁶, 2.6 × 10⁶, 3.1 × 10⁶, and 2.2 × 10⁶ cm^?3, respectively. Since the rainfall was concentrated in summer, the wet deposition had a significant effect on removing OH radicals. Among the four pollutants (including ozone (O₃), volatile organic compounds (VOCs), nitrogen dioxide (NO₂) and fine particulate matter (PM_2.5)), the variation of OH radicals were closely related to ozone concentration especially in spring and summer. In autumn, the correlation between PM_2.5 and OH radicals were the closest among the observing pollutants and its formation mechanism was different conventional regeneration pathway. In Event 1, high concentration of ozone was the main source of OH radicals; under the high humidity condition, except for ozone, the multiple factors including VOCs, NO₂ and PM_2.5 interplayed and leaded to the Event 2.     

Year-round observation of atmospheric inorganic aerosols in urban Beijing: Size distribution, source analysis, and reduction mechanism

To investigate particle characteristics and find an effective measure to control severe particle pollution, year-round observation of size-segregated inorganic aerosols was conducted in Beijing from January to December, 2016. The sampled atmospheric particles all presented bimodal size distribution at four pollution levels (clear, slight pollution, moderate pollution and severe pollution), and peak values appeared at the size range of 0.7-2.1 μm and >9.0 μm, respectively. As dominant particle compositions, NO₃⁻, SO₄²⁻, and NH₄⁺ in four pollution levels all showed significant peaks in fine mode, especially at the size range of 1.1-2.1 μm. Secondary inorganic aerosols accounted for about 67.6% (36.3% (secondary sulfates) + 31.3% (secondary nitrates)) of the total sources of fine particles in urban Beijing. Severe pollution of fine particles was mainly caused by the air masses transported from nearby western and southern areas, which are industrial and densely populated region, respectively. Sensitivity tests further revealed that the control measures focusing on ammonium emission reduction was the most effective for particle pollution mitigation, and fine particles all showed nonlinear responses after reducing ammonium, nitrate, and sulfate concentrations, with the fitting curves of y = -120.8x - 306.1x² + 290.2x³, y = -43.5x - 67.8x², and y = -25.8x - 110.4x² + 7.6x³, respectively (y and x present fine particle mass variation (μg/m³) and concentration reduction ratio (CRR)/100 (dimensionless)). Overall, our study presents useful information for understanding the characteristics of atmospheric inorganic aerosols in urban Beijing, as well as offers policy makers with effective measure for mitigating particle pollution.     

Chemical characteristics and source apportionment of PM2.5 in a petrochemical city: Implications for primary and secondary carbonaceous component

To study the pollution features and underlying mechanism of PM_2.5 in Luoyang, a typical developing urban site in the central plain of China, 303 PM_2.5 samples were collected from April 16 to December 29, 2015 to analyze the elements, water soluble inorganic ions, organic carbon and elemental carbon. The annual mean concentration of PM_2.5 was 142.3 μg/m³, and 75% of the daily PM_2.5 concentrations exceeded the 75 μg/m³. The secondary inorganic ions, organic matter and mineral dust were the most abundant species, accounting for 39.6%, 19.2% and 9.3% of the total mass concentration, respectively. But the major chemical components showed clear seasonal dependence. SO₄^2? was most abundant specie in spring and summer, which related to intensive photochemical reaction under high O₃ concentration. In contrast, the secondary organic carbon and ammonium while primary organic carbon and ammonium significantly contributed to haze formation in autumn and winter, respectively. This indicated that the collaboration effect of secondary inorganic aerosols and carbonaceous matters result in heavy haze in autumn and winter. Six main sources were identified by positive matrix factorization model: industrial emission, combustion sources, traffic emission, mineral dust, oil combustion and secondary sulfate, with the annual contribution of 24%, 20%, 24%, 4%, 5% and 23%, respectively. The potential source contribution function analysis pointed that the contribution of the local and short-range regional transportation had significant impact. This result highlighted that local primary carbonaceous and precursor of secondary carbonaceous mitigation would be key to reduce PM_2.5 and O₃ during heavy haze episodes in winter and autumn.     

Heavy haze pollution during the COVID-19 lockdown in the Beijing-Tianjin-Hebei region, China

To investigate the characteristics of particulate matter with an aerodynamic diameter less than 2.5 μm (PM_2.5) and its chemical compositions in the Beijing-Tianjin-Hebei (BTH) region of China during the novel coronavirus disease (COVID-19) lockdown, the ground-based data of PM_2.5, trace gases, water-soluble inorganic ions, and organic and elemental carbon were analyzed in three typical cities (Beijing, Tianjin, and Baoding) in the BTH region of China from 5-15 February 2020. The PM_2.5 source apportionment was established by combining the weather research and forecasting model and comprehensive air quality model with extensions (WRF-CAMx). The results showed that the maximum daily PM_2.5 concentration reached the heavy pollution level (>150 μg/m³) in the above three cities. The sum concentration of SO₄²⁻, NO₃⁻ and NH₄⁺ played a dominant position in PM_2.5 chemical compositions of Beijing, Tianjin, and Baoding; secondary transformation of gaseous pollutants contributed significantly to PM_2.5 generation, and the secondary transformation was enhanced as the increased PM_2.5 concentrations. The results of WRF-CAMx showed obviously inter-transport of PM_2.5 in the BTH region; the contribution of transportation source decreased significantly than previous reports in Beijing, Tianjin, and Baoding during the COVID-19 lockdown; but the contribution of industrial and residential emission sources increased significantly with the increase of PM_2.5 concentration, and industry emission sources contributed the most to PM_2.5 concentrations. Therefore, control policies should be devoted to reducing industrial emissions and regional joint control strategies to mitigate haze pollution.     

Nitrogenous and carbonaceous aerosols in PM2.5 and TSP during pre-monsoon: Characteristics and sources in the highly polluted mountain valley

This study reports for the first time a comprehensive analysis of nitrogenous and carbonaceous aerosols in simultaneously collected PM_2.5 and TSP during pre-monsoon (March–May 2018) from a highly polluted urban Kathmandu Valley (KV) of the Himalayan foothills. The mean mass concentration of PM_2.5 (129.8 µg/m³) was only ~25% of TSP mass (558.7 µg/ m³) indicating the dominance of coarser mode aerosols. However, the mean concentration as well as fractional contributions of water-soluble total nitrogen (WSTN) and carbonaceous species reveal their predominance in find-mode aerosols. The mean mass concentration of WSTN was 17.43±4.70 µg/m³ (14%) in PM_2.5 and 24.64±8.07 µg/m³ (5%) in TSP. Moreover, the fractional contribution of total carbonaceous aerosols (TCA) is much higher in PM_2.5 (~34%) than that in TSP (~20%). The relatively low OC/EC ratio in PM_2.5 (3.03 ± 1.47) and TSP (4.64 ± 1.73) suggests fossil fuel combustion as the major sources of carbonaceous aerosols with contributions from secondary organic aerosols. Five-day air mass back trajectories simulated with the HYSPLIT model, together with MODIS fire counts indicate the influence of local emissions as well as transported pollutants from the Indo-Gangetic Plain region to the south of the Himalayan foothills. Principal component analysis (PCA) also suggests a mixed contribution from other local anthropogenic, biomass burning, and crustal sources. Our results highlight that it is necessary to control local emissions as well as regional transport while designing mitigation measures to reduce the KV's air pollution.     

Cross-boundary transport and source apportionment for PM2.5 in a typical industrial city in the Hebei Province, China: A modeling study

Cross-boundary transport of air pollution is a difficult issue in pollution control for the North China Plain. In this study, an industrial district (Shahe City) with a large glass manufacturing sector was investigated to clarify the relative contribution of fine particulate matter (PM_2.5) to the city's high levels of pollution. The Nest Air Quality Prediction Model System (NAQPMS), paired with Weather Research and Forecasting (WRF), was adopted and applied with a spatial resolution of 5 km. During the study period, the mean mass concentrations of PM_2.5, SO₂, and NO₂ were observed to be 132.0, 76.1, and 55.5 μg/m³, respectively. The model reproduced the variations in pollutant concentrations in Shahe at an acceptable level. The simulation of online source-tagging revealed that pollutants emitted within a 50-km radius of downtown Shahe contributed 63.4% of the city's total PM_2.5 concentration. This contribution increased to 73.9±21.2% when unfavorable meteorological conditions (high relative humidity, weak wind, and low planetary boundary layer height) were present; such conditions are more frequently associated with severe pollution (PM_2.5 ≥ 250 μg/m³). The contribution from Shahe was 52.3±21.6%. The source apportionment results showed that industry (47%), transportation (10%), power (17%), and residential (26%) sectors were the most important sources of PM_2.5 in Shahe. The glass factories (where chimney stack heights were normally < 70 m) in Shahe contributed 32.1% of the total PM_2.5 concentration in Shahe. With an increase in PM_2.5 concentration, the emissions from glass factories accumulated vertically and narrowed horizontally. At times when pollution levels were severe, the horizontally influenced area mainly covered Shahe. Furthermore, sensitivity tests indicated that reducing emissions by 20%, 40%, and 60% could lead to a decrease in the mass concentration of PM_2.5 of of 12.0%, 23.8%, and 35.5%, respectively.     

环境与人口、经济和科技发展的协同探析

本文从环境与人口、经济和科技之间的相依关系出发,探讨了诸因素相互关联的内在协同机理,简析了IPAT模型的建构与应用.嗣后,利用IPAT模型解析了中国近15年来人口、经济和科技发展对环境影响的贡献差异;指出经济规模的迅速扩展和落后技术支持下的传统生产方式是加剧环境恶化的元凶,且技术转型期的负面影响也是不可忽视的重要因素;进而提出了中国未来环境与人口、经济和科技协同演化的对策措施.     

环境与人口、经济和科技发展的协同探析

本文从环境与人口、经济和科技之间的相依关系出发，探讨了诸因素相互关联的内在协同机理，简析了IPAT模型的建构与应用。嗣后，利用IPAT模型解析了中国近15年来人口、经济和科技发展对环境影响的贡献差异；指出经济规模的迅速扩展和落后技术支持下的传统生产方式是加剧环境恶化的元凶，且技术转型期的负面影响也是不可忽视的重要因素；进而提出了中国未来环境与人口、经济和科技协同演化的对策措施。     

论知情权的确认和保障

知情权作为人权的重要组成部分愈来愈受到人们的广泛关注和重视,但我国的宪法和宪法性文件并没有关于知情权的明文规定.本文从知情权的概念、确认知情权的必要性与可行性、保障知情权的有效途径等方面试就以法律的形式确认和保障知情权的问题进行分析和探讨,提出我国公民知情权的保护应该通过建立与信息公开、新闻自由、隐私权密切相关的法律去实现,以使知情权规范化、制度化.     

Biomimetics and the case of the remarkable ragworms

Biomimetics is a rapidly growing field both as an academic and as an applied discipline. This paper gives a short introduction to the current status of the discipline before it describes three approaches to biomimetics: the mechanism-driven, which is based on the study of a specific mechanism; the focused organism-driven, which is based on the study of one function in a model organism; and the integrative organism-driven approach, where multiple functions of a model organism provide inspiration. The first two are established approaches and include many modern studies and the famous biomimetic discoveries of Velcro and the Lotus-Effect, whereas the last approach is not yet well recognized. The advantages of the integrative organism-driven approach are discussed using the ragworms as a case study. A morphological and locomotory study of these marine polychaetes reveals their biomimetic potential, which includes using their ability to move in slippery substrates as inspiration for novel endoscopes, using their compound setae as models for passive friction structures and using their three gaits, slow crawling, fast crawling, and swimming as well as their rapid burrowing technique to provide inspiration for the design of displacement pumps and multifunctional robots.     

微博对大学生思想政治教育工作的影响及其对策研究

随着科技的快速发展,社会也发生了巨大的变化。新兴媒体大量崛起,快速蔓延到人们的生活中,特别是在大学生的生活中占据了重要的地位。这是一种对传统的教育模式的挑战。但是,这并不是单纯的只有挑战,同时伴随着一定的机遇。微博是一种新出现的网络社交平台,因此,深受大学生的喜爱,对于大学生思想政治教育具有一定的影响,如何利用好微博这一平台,在本文中做出了探讨。     

浅议环境与发展综合决策制度的建立与实施

衽环境与发展综合决策势在必行。传统的决策方式在存在许多不足，必须综合考虑环境发展和经济发展，在思想上，经济目标上，环境保护部门与有关部门相互关系上以及工作措施上体现综合决策思想。     

从世界可持续发展高峰会议的成果看能源问题的紧迫性与艰巨性

本文首先概要评述了世界可持续发展高峰会议的成果;其次,从可持续发展资源稀缺性的角度和延缓全球变暖的角度阐述了能源问题的紧迫性;再次,从国际气候变化谈判和这次世界峰会能源谈判的角度分析了能源问题的艰巨性。最后,对中国应取的立场和措施提出了建议。     

近20年大、小凌河入海径流量和输沙量变化及其驱动力分析

利用大、小凌河1988—2007年的流量和输沙量资料,阐述了这2条河流入海径流量和输沙量的年内分配特征,应用Mann-Kendall秩检验法分析了其多年变化特征,并进一步探讨了2条河流入海径流和输沙量变化的驱动力. 结果表明:大、小凌河入海径流量和输沙量的年内分配极不均衡,分别有60%和90%以上集中在汛期(6—9月);近20年来,大、小凌河入海径流量和输沙量年际变化趋势基本一致. 1999年为2条河流入海径流量和输沙量年际变化的突变年,1999年前呈增大趋势,而从1999年开始明显减少. 流域降水变化可能是促使大、小凌河入海径流量和输沙量变化的主要原因,同时人类活动的影响也起到了较大的促进作用.      

航道疏浚对珠江口附近海洋生态环境影响及预防措施

广州港航道疏浚工程中开挖和处理底泥会产生大量悬浮物，悬浮物及其含有的各种污染物将影响珠江口近海洋生态和渔业。本文主要介绍污染情况以及预防措施。通过扩散实验认为与航道疏浚工程有一定的污染，但是影响不大。通过施工前及施工期间监测结果相对照，认为航道疏浚工程对珠江口附近海洋生态环境基本没有产生大的影响，疏浚工程所采取的环保措施是极为有效的。