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Chemical characteristics and source apportionment of PM_(2.5) between heavily polluted days and other days in Zhengzhou, China 被引量:24
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作者 Nan Jiang Qiang Li +5 位作者 Fangcheng Su Qun Wang Xue Yu Panru Kang Ruiqin Zhang Xiaoyan Tang 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2018年第4期188-198,共11页
PM(2.5) samples were collected in Zhengzhou during 3 years of observation, and chemical characteristics and source contribution were analyzed. Approximately 96% of the daily PM(2.5) concentrations and annual avera... PM(2.5) samples were collected in Zhengzhou during 3 years of observation, and chemical characteristics and source contribution were analyzed. Approximately 96% of the daily PM(2.5) concentrations and annual average values exceeded the Chinese National Ambient Air Quality Daily and Annual Standards, indicating serious PM(2.5) pollution. The average concentration of water-soluble inorganic ions was 2.4 times higher in heavily polluted days(daily PM32.5 concentrations &gt; 250 μg/mand visibility &lt; 3 km) than that in other days, with sulfate, nitrate, and ammonium as major ions. According to the ratio of NO-3/SO2-4,stationary sources are still the dominant source of PM(2.5) and vehicle emission could not be ignored. The ratio of secondary organic carbon to organic carbon indicated that photochemical reactivity in heavily polluted days was more intense than in other days.Crustal elements were the most abundant elements, accounting for more than 60% of 23 elements. Chemical Mass Balance results indicated that the contributions of major sources(i.e., nitrate, sulfate, biomass, carbon and refractory material, coal combustion, soil dust,vehicle, and industry) of PM(2.5) were 13%, 16%, 12%, 2%, 14%, 8%, 7%, and 8% in heavily polluted days and 20%, 18%, 9%, 2%, 27%, 14%, 15%, and 9% in other days, respectively.Extensive combustion activities were the main sources of polycyclic aromatic hydrocarbons during the episode(Jan 1-9, 2015) and the total benzo[a]pyrene equivalency concentrations in heavily polluted days present significant health threat. Because of the effect of regional transport, the pollution level of PM(2.5) in the study area was aggravated. 展开更多
关键词 PM2.5 Water soluble inorganic ions Secondary organic carbon CMB Back trajectory analysis
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Boron Oxide Glasses and Nanocomposites: Synthetic, Structural and Statistical Approach 被引量:1
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作者 Hristo Hristov Miroslava Nedyalkova +1 位作者 Sergio Madurga Vasil Simeonov 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2017年第6期535-540,共6页
Three different precursors of boron-aqua and glycerol solutions of boric acid and ethanol solution of trimethyl borate were used for the preparation of organic–inorganic advanced materials. The films and bulk materia... Three different precursors of boron-aqua and glycerol solutions of boric acid and ethanol solution of trimethyl borate were used for the preparation of organic–inorganic advanced materials. The films and bulk materials samples were heat treated at 100, 400, 800?C for 2 h. The hybrid samples were stable and transparent until 100?C. The further increase of temperature to 400?C led to destruction of samples, and at 800?C they were molten. The structural changes during the pyrolysis were studied by Fourier transform infrared spectroscopy, differential thermal analysis, and X-ray diffraction. Details of surface morphology were observed by scanning electron microscopy. The obtained BO_3 and BO_4 groups were identified in the molten materials after pyrolysis. The quantities and order of borate structural units as well as residual carbon in the networks depended on boron precursor type. PVA/PEG/B_2O_3 hybrid materials were proved to be appropriate precursors for synthesizing borate and carboborate glass and carbon/borate glass nanocomposites. To access the impact of the experimental conditions on the structural changes of the nanocomposites, cluster analysis of the IR-spectral data was used as a classification method. 展开更多
关键词 Organic–inorganic hybrid materials Borate glass Nanocomposites Cluster analysis
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