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He J.,The University of Nottingham Ningbo, China | He J.,National University of Singapore | Xu H.,Zhejiang Meteorological Science Institute | Balasubramanian R.,National University of Singapore | And 2 more authors.
Aerosol and Air Quality Research

This report describes the results of an inter-comparison study conducted for the sampling and analysis of NO2 and SO2 by using different type of passive samplers in tropical urban environment. For this purpose, field experiments were proposed to be conducted by two round robin tests from Sept. 2007 to Aug. 2008 in Singapore. A set of different types of passive samplers have been exposed to ambient air at atmospheric research station in National University of Singapore along with suitable active samplers (as reference method) for a sufficient period of time (3-4 weeks). Annular denuder system (ADS) active sampling data showed that NO2 concentration level (23.8-28.1 ppb) in Singapore was slightly higher than the WHO guideline but SO2 concentration (12.5-14.9 ppb) was approximately twice the value of WHO guideline. For the two round robin tests, accuracy analysis by using active sampling data as reference demonstrated that grand mean values from passive air sampling (PAS) and active sampler average concentrations, for both NO2 and SO2, are in close agreement with each other. Precision evaluation based on the triplicate samplers co-located at the same sampling site - Singapore showed that most of the passive samplers applied here had repeatability. ANOVA statistical analysis also showed no significant difference between the measurement data obtained by different type of passive samplers for both round robin tests in Singapore. © Taiwan Association for Aerosol Research. Source

Tomatis M.,The University of Nottingham Ningbo, China | Xu H.-H.,Zhejiang Meteorological Science Institute | He J.,The University of Nottingham Ningbo, China | Zhang X.-D.,University of Shanghai for Science and Technology
Journal of Chemistry

Volatile organic compounds (VOCs) emitted from anthropogenic sources pose direct and indirect hazards to both atmospheric environment and human health due to their contribution to the formation of photochemical smog and potential toxicity including carcinogenicity. Therefore, to abate VOCs emission, the catalytic oxidation process has been extensively studied in laboratories and widely applied in various industries. This report is mainly focused on the benzene, toluene, ethylbenzene, and xylene (BTEX) with additional discussion about chlorinated VOCs. This review covers the recent developments in catalytic combustion of VOCs over noble metal catalysts, nonnoble metal catalysts, perovskite catalysts, spinel catalysts, and dual functional adsorbent-catalysts. In addition, the effects of supports, coke formation, and water effects have also been discussed. To develop efficient and cost-effective catalysts for VOCs removal, further research in catalytic oxidation might need to be carried out to strengthen the understanding of catalytic mechanisms involved. © 2016 Marco Tomatis et al. Source

Xu J.-S.,The University of Nottingham Ningbo, China | Xu H.-H.,Zhejiang Meteorological Science Institute | Xiao H.,Chinese Institute of Urban Environment | Xiao H.,Chinese Academy of Sciences | And 5 more authors.
Atmospheric Research

Due to the rapid industrialization of the Yangtze River Delta (YRD) region in China, heavy air pollution episodes have occurred frequently over the past five years which are of great concern due to their environmental and health impacts. To investigate the chemical characteristics of the highly polluted aerosols in this region, a sampling campaign had been conducted in Ningbo from 3 December 2012 to 27 June 2013, during which a month long high pollution episode had been captured. Daily average PM2.5 concentrations during high and low pollution periods were 111 μg m- 3 and 53 μg m- 3, respectively. The most polluted day was 8 January 2013 with a PM2.5 concentration up to 175 μg m-3. To understand the origin of the highly polluted aerosols, meteorological conditions, air mass backward trajectories, distribution of fire spots in surrounding areas and various categories of aerosol pollutants were analyzed, including trace metals, inorganic species, PAHs and anhydrosugars. Total metal concentrations were 3.8 and 1.6 μg m- 3 for the high and low pollution episodes, respectively, accounting for 3.4% and 3.1% of the total PM2.5 mass. Total concentrations of ionic species accounted for more than 50.0% of the PM2.5 by mass, with dominant ions (nitrate, sulfate, ammonium) accounting for over 42.0% of the PM2.5 mass concentrations in both periods. During the high pollution episode, enhanced Cd-Pb and biomarker (levoglucosan, mannosan) levels indicated the contributions from coal combustion, traffic and biomass burning to fine aerosol PM2.5. The average diagnostic ratio of Fla/(Fla + Pyr) was 0.54 in high pollution episode, which was intermediate between that for wood (>0.50) and coal combustion (0.58). BaP/Bpe was 0.49 and 0.30 for the highly and lightly polluted aerosols respectively, associated with the significant non-traffic emissions (<0.60). In addition, stagnant weather conditions during the high pollution period and long-range transport of air masses from heavy industries and biomass burning from northern China to Ningbo could be considered as the main factors for the formation of the aerosols during high pollution period. © 2016 Elsevier B.V. Source

Xu H.-H.,Zhejiang Meteorological Science Institute | Pu J.-J.,Zhejiang Meteorological Science Institute | He J.,The University of Nottingham Ningbo, China | Liu J.,Zhejiang Meteorological Science Institute | And 2 more authors.
Advances in Meteorology

In order to understand the formation and evolution of recurrent severe haze pollution episodes in Yangtze River Delta, China, a short comparative sampling campaign was conducted at the Lin'an background monitoring station from 25 November 2013 to 14 December 2013. The characteristic concentrations of PM2.5, black carbon, CO2, CO, and CH4 have been systematically recorded at the abovementioned site. Coupled with detailed analysis of air backward trajectories, fire spot distribution surrounding the studied site and meteorological impacts, temporal trend, diurnal variation, and intercorrelation of the aforementioned species have also been comprehensively investigated throughout prehaze, haze, and posthaze periods. © 2016 Hong-Hui Xu et al. Source

Li X.,Capital Normal University | Zhang R.,Capital Normal University | Cong X.,Capital Normal University | Cheng L.,Capital Normal University | And 2 more authors.
Atmospheric Pollution Research

PM1.0and PM2.5 samples are collected in Lin'an, a Regional Atmosphere Background Station in spring (1–30 April), summer (1–31 July), autumn (1–31 October) and winter (1–31 January) in 2011 to investigate the seasonal characteristics of aerosol pollution in the Yangtze River Delta region. The daily concentrations of water-soluble ions are 24.6 ± 12.0 mg m–3 and 36.6 ± 23.6 μg m–3 in PM1.0 and PM2.5, respectively. SO4 2–, NO3 – and NH4 + are the dominant contributors of water-soluble ions, accounting for 78.6% (spring), 83.5% (summer), 80.6% (autumn) and 81.9% (winter) of the total ions measured in PM1.0 and 80.2% (spring), 85.4% (summer), 78.9% (autumn) and 78.9% (winter) inPM2.5. Seasonal variation is observed, with the lowest ions concentration in winter and the highest one in summer. Nevertheless, the crustal elements (e.g., Ca,Mg, Al, Fe, etc.) have the highest concentrations in spring. Most of the pollution species (Sb, Se, Cd, Pb, As and Zn) have enrichment factor values higher than 100, implying a strong possibility that the air pollution originates from anthropogenic sources and have no evident seasonal variation. The high concentration of Kþ and biomass burning potassium (K+ BB) in PM2.5 in autumn and winter and its good correlation with black carbon (r = 0.74) suggest that the most severe pollution derives from biomass burning. Factor analysis results indicate that road dust, combustion processes (biomass burning and fossil fuels combustion), sea salt from marine sources and industrial activities are main sources of aerosol pollution in Lin'an. © 2015 Turkish National Committee for Air Pollution Research and Control. Production and hosting by Elsevier B.V. All rights reserved. Source

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