Ehlerscooke0360

To reveal the pollution characteristics and the health risks of the trace heavy metals in the atmospheric particles in Baoding, Hebei province, PM2.5 samples were collected using a middle volume sampler, and the mass concentrations of V, Cr, Mn, Co, Ni, Cu, Zn, As, Cd, and Pb in the samples were determined by microwave digestion-inductively coupled plasma-mass spectrometry (ICP-MS). The results showed that the PM2.5 concentration in Baoding ranged from 16.84-476.2 μg·m-3. During sampling, 65 samples were above the second-level standard of the Ambient Air Quality Standards (GB 3095-2012) by 54.2%. The most heavy metal elements showed higher levels in nighttime than during the daytime, except for except for Ni, Mn, and Co. Obvious seasonal variation was found with the trend of winter > autumn > spring > summer. The enrichment factors for Cu, Zn, Pb, and Cd were more than 1.5, indicating that those metals mainly came from anthropogenic emissions, such as traffic sources. Health risk assessment results indicated that the non-carcinogenic risk of heavy metals in PM2.5 in Baoding was small, and the carcinogenic risk resulting form As, Cr, Cd, and Co was greater for adults than for children.In order to explore the characteristics of PM2.5 and water-soluble ions in Shenyang in winter, the URG-9000D online monitoring system was used to continuously sample PM2.5 and gas components during 2018. AK 7 purchase The results indicated that the average concentration of PM2.5 in Shenyang during the sampling period was 80.67 μg·m-3, and the total water-soluble ion concentration ranged from 2.68 to 132.79 μg·m-3. Compared with clean days, the proportion of NO3-, SO42-, and NH4+ (SNA) in polluted days increased significantly, reached 43.7% of PM2.5. The rapid accumulation of SO2 in a short period of time made atmospheric PM2.5 explosively increase in Shenyang in winter. A Pearson correlation analysis showed that the correlation coefficients of SNA, Cl-, and PM2.5 were all above 0.78, indicating that the main contribution components of winter PM2.5 in Shenyang were SNA and Cl-. The apportionment of PMF sources indicated that the sources of pollutants in winter in Shenyang mainly included secondary reaction sources, coal and biomass combustion sources, and dust sources.To study the characteristics of PM2.5 pollution and the potential sources of its main components in the central plain urban agglomeration in autumn and winter, PM2.5 samples were collected continually in the four typical cities of Zhengzhou, Luoyang, Anyang, and Xinxiang from October 2018 to January 2019. X-ray fluorescence spectrometry, carbon analysis methods, and ion chromatography were used to determine 18 kinds of inorganic elements, organic carbon (OC)/elemental carbon (EC), and 9 kinds of water-soluble inorganic ions. According to the daily PM2.5 concentration, three pollution levels were divided, and the comparative analysis for the spatial and temporal variation of PM2.5 and its main components, i.e., NO3-, OC, and 18 kinds of inorganic elements, were studied via the calculation of the nitrogen oxidation rate (NOR), secondary organic carbon (SOC), and enrichment factor. The emission sources and their contribution rates of PM2.5 pollution level in the four cities were calculated by a chemical mass bal the Anyang and Xinxiang areas were mainly concentrated in Henan province and the Beijing-Tianjin-Hebei transport belt. The pollution levels of OC in Anyang and Xinxiang were also affected by the northwest Anhui, southwest Shandong, southeast Shanxi, and north Shaanxi.Pollution occurs in the boundary layer, and the thermal and dynamic vertical structure of the boundary layer has a significant influence on the formation of heavy pollution episodes. Based on unmanned aerial vehicle (UAV) sounding, ground-based remote sensing and numerical modeling, this paper analyzes the vertical structure of the boundary layer and the causes of pollution during the heavy pollution episode in Tianjin from January 10 to 15, 2019, with a view to strengthening the understanding of the influence law of boundary layer processes on heavy pollution in northern coastal cities and improving the accuracy of weather forecasts and heavy pollution warnings. The results show that atmospheric temperature stratification had a significant influence on the formation, persistence, and dissipation of heavy pollution episodes. During an episode, accompanied by the development and dissipation of the inversion layer, a high PM2.5 concentration area developed to the upper atmosphere with a height of over 300 m in affected the improvement of air quality by cold air. The strong temperature inversion at the top of the fog resulted in the failure of the cold air to transmit to the ground through turbulent shear stress in the S3 stage. There was an obvious difference in wind speed between the upper and lower air. The influence of cold air on the ground was delayed, and the effect of it was weakened. Thus, the heavy pollution episode could not be alleviated completely.Since 2013, the Chinese government implemented the Air Pollution Prevention and Control Action Plan. As a result, the atmospheric concentrations of sulfate reduced significantly, whereas the nitrate concentrations remain relatively high due to the excess of ammonia (NH3). To date, there is no official observation network monitoring NH3 concentrations in China. Previous studies have focused on NH3 or ammonium (NH4+) separately. These limitations hinder a complete understanding of their dynamic changes due to the rapid gas-to-particle conversion. In this study, the concentrations of NH3 and NH4+ were measured concurrently in urban Beijing during autumn 2019 utilizing an acid-coated denuder-filter combination with a time resolution from 2 h (PM2.5>35 μg·m-3) to 5 h (PM2.575 μg·m-3) and non-polluted (PM2.5 less then 75 μg·m-3) days, peaking at 2130-0530 and 0530-0830, respectively. The NH3 concentrations on polluted days were relatively lower during 1730-2130, which may be related to higher wind speeds. In contrast to NH3, NH4+ had an obvious peak during 1730-2130 due to the formation of ammonium nitrate. The meteorological conditions favor the gas-to-particle conversion on polluted days, resulting in a lower NH3/NH4+ ratio of 0.8. However, this value may reach 2.8 on non-polluted days. The concentrations of NH3, CO, NO2, SO2, and PM2.5 in the emission control period showed a significant increase greater than or comparable to those in the non-control period by 54.2%, 40.4%, 33.3%, 0%, and 49.4%, respectively. This result shows that the stagnant conditions offset the benefit of emission control actions implemented during and before the National Celebration Day.