Size distributions of particulate sulfate, nitrate, and ammonium at a coastal site in Hong Kong

Zhuang, Hong; Chan, Chak K.; Fang, Ming; Wexler, Anthony S.

doi:10.1016/s1352-2310(98)00305-7

Cited by 240 publications

(149 citation statements)

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“…Studies on the size distribution of ambient aerosol species in Hong Kong are mainly based on size-resolved sampling by cascade impactors or serial collocated samplers with different inlet cutoff size diameters. Sulfate and ammonium were observed as the dominant species in fine particles (D p < 1.8 μm), while nitrate was mainly present in the coarse mode [Zhuang et al, 1999]. Solvent extractable organics were shown to be enriched in PM 2.5 and to exhibit a seasonal dependency with higher concentrations and a shift toward larger particle size in the dry winter season [Zheng et al, 2008].…”

Section: Introductionmentioning

confidence: 90%

“…mode, with a mode diameter centered at 3.95 μm [Zhuang et al, 1999]. With a size cut of 2.5 μm, it is likely that MARGA detects larger fractions of coarse mode nitrate than the AMS.…”

Section: Comparison Of Ams Marga and Ecoc Analyzer Measurementsmentioning

confidence: 99%

“…In Hong Kong, the number of lowvisibility (<8 km) days has continuously increased since the 1980s and has seen a dramatic rise since the early 2000s [Chan and Yao, 2008]. Particulate matter has been recognized as a major factor in Hong Kong's urban air quality, affecting visibility [Zhuang et al, 1999] and human health [Thach et al, 2011]. Studies on particulate matter in Hong Kong have been traditionally based on filter sampling and off-line analysis including elemental and organic carbon (ECOC) analysis, gas chromatography-mass spectrometry, ion chromatography, gravimetric analysis, and absorptive colorimetry Li and Yu, 2010;Yao et al, 2007].…”

Section: Introductionmentioning

confidence: 99%

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Physical and chemical characterization of ambient aerosol by HR‐ToF‐AMS at a suburban site in Hong Kong during springtime 2011

Lee

Wang

et al. 2013

JGR Atmospheres

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[1] An Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) has been employed in a field sampling campaign at a suburban coastal site in Hong Kong in springtime 2011 to provide insights into the size-resolved chemical composition of nonrefractory submicron aerosol species. This is the first time that such detailed real-time measurements have been made in Hong Kong. The total nonrefractory PM 1 was dominated by sulfate (51.0%) and organics (28.2%) with considerable acidity (average in situ pH = 0.95) and a characteristic bimodal particle size distribution with peaks at 200 and 570 nm of vacuum aerodynamic diameter (D va ). Source apportionment of organic aerosol yielded three characteristic aerosol fractions (hydrocarbon-like organic aerosol, semivolatile organic aerosol and low-volatile organic aerosol) with distinct temporal patterns and distributions in different particle size regions. The influence of air mass origin on species concentrations, particle size distributions and elemental ratios was investigated using backtrajectory analysis. Larger particle diameters, greater fractions of oxygenated organic aerosol and higher organic-to-carbon ratios were observed during coastal and continental air mass influence. Three major pollution events with elevated nonrefractory PM 1 concentrations were observed in the sampling period, which were related to distinct meteorological and circulatory conditions. Accumulation and redistribution of local and regional pollutants were notable in a period of strong land-sea breeze over the Pearl River Delta region, with considerable photochemical activity and particle aging. Increased fractions of oxygenated organic aerosol were apparent in foggy conditions, illustrating the importance of aqueous phase oxidation processes in a cooler and more humid time period.

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Section: Introductionmentioning

confidence: 90%

“…mode, with a mode diameter centered at 3.95 μm [Zhuang et al, 1999]. With a size cut of 2.5 μm, it is likely that MARGA detects larger fractions of coarse mode nitrate than the AMS.…”

Section: Comparison Of Ams Marga and Ecoc Analyzer Measurementsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Physical and chemical characterization of ambient aerosol by HR‐ToF‐AMS at a suburban site in Hong Kong during springtime 2011

Lee

Wang

et al. 2013

JGR Atmospheres

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“…The datasets consist of monthly-averaged NO 2 measurements from a total of 137 monitoring locations, and annual averages of SO 4 measurements from 166 monitoring locations over the 15-year period between 1988 and 2002. SO 4 was measured as a mass constituent of PM 10 (particulate matter of 10 microns or less in aerodynamic diameter, although previous studies indicate that much of the SO 4 will have particle sizes below 2.5 microns in aerodynamic diameter; see, e.g., (20)). Figure 1 shows all the measurement sites for each pollutant during the study period.…”

Section: Nitrogen Dioxide and Sulfate Datamentioning

confidence: 99%

“…There are two main products when using SOM: (i) a low-dimensional model of the high-dimensional input space, the SOM itself; and (ii) a low-dimensional representation of high-dimensional vectors after they are mapped onto the trained SOM (17, pp. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. The former is often useful in explaining patterns observed in the latter, once both are given visual form, as demonstrated in section 4.2.…”

Section: Dimensionality Reductionmentioning

confidence: 99%

Multi-Perspective Analysis and Spatiotemporal Mapping of Air Pollution Monitoring Data

Kolovos

Skupin

Jerrett

et al. 2010

Environ. Sci. Technol.

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Space-time data analysis and assimilation techniques in atmospheric sciences typically consider input from monitoring measurements. The input is often processed in a manner that acknowledges characteristics of the measurements (e.g., underlying patterns, fluctuation features) under conditions of uncertainty, leads to the derivation of secondary information that serves study-oriented goals, and provides input to space-time prediction techniques. We present a novel approach that blends a rigorous space-time prediction model (Bayesian Maximum Entropy, BME) with a cognitively informed visualization of high-dimensional data (spatialization). The combined BME and spatialization approach (BME-S) is used to study monthly-averaged NO 2 and mean annual SO 4 measurements in California over the 15-year period 1988-2002. Using the original scattered measurements of these two pollutants BME generates spatiotemporal predictions on a regular grid across the state. Subsequently, the prediction network undergoes the spatialization transformation into a lower-dimensional geometric representation, aimed at revealing patterns and relationships that exist within the input data. The proposed BME-S provides a powerful spatiotemporal framework to study a variety of air pollution data sources.

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Insights into factors affecting nitrate in PM_2.5 in a polluted high NO_x environment through hourly observations and size distribution measurements

et al. 2014

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Nitrate, a major PM 2.5 component in polluted environments, could be greatly elevated during pollution episodes. In this study, nitrate and other inorganic ions on PM 2.5 were measured half hourly at a residential location in Hong Kong in December 2009. Hourly nitrate concentrations in PM 2.5 varied from 0.8 to 40.5 μg m À3 . In an episode during which hourly visibility was down to 3.7 ± 1.0 km and NO 2 was 80.7 ± 14.4 ppb, PM 2.5 NO 3 À reached 27.8 ± 8.0 μg m À3 ,~6 times the level during the normal hours. Nitrate was fully balanced by NH 4 + , indicating abundant presence of NH 3 . Size-segregated measurements showed 84% of nitrate was in the fine mode during the episode and also suggested that less acidic fine particles and less abundant sea-salt particles were the contributing factors to the dominant presence in the fine mode. An observation-based model for secondary inorganic aerosols was applied to investigate the relative importance of homogeneous and heterogeneous reactions to production of NO 3 À potential (sum of HNO 3 (g) and aerosol nitrate). The modeling analysis shows that both formation pathways were significantly more active during the episode. Gas phase production of HNO 3 through reaction of NO 2 + OH dominated during the initial rapid buildup of nitrate around noon time, but the heterogeneous N 2 O 5 hydrolysis pathway made a sizable contribution in the subsequent few hours due to sustained high-NO 2 concentrations combined with reduced photolysis loss of N 2 O 5 . This case study illustrates the important role of NH 3 and NO 2 in elevating PM 2.5 in a high-NO x environment through the formation of nitrate.

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Size distributions of particulate sulfate, nitrate, and ammonium at a coastal site in Hong Kong

Cited by 240 publications

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Physical and chemical characterization of ambient aerosol by HR‐ToF‐AMS at a suburban site in Hong Kong during springtime 2011

Physical and chemical characterization of ambient aerosol by HR‐ToF‐AMS at a suburban site in Hong Kong during springtime 2011

Multi-Perspective Analysis and Spatiotemporal Mapping of Air Pollution Monitoring Data

Insights into factors affecting nitrate in PM_2.5 in a polluted high NO_x environment through hourly observations and size distribution measurements

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Size distributions of particulate sulfate, nitrate, and ammonium at a coastal site in Hong Kong

Cited by 240 publications

References 0 publications

Physical and chemical characterization of ambient aerosol by HR‐ToF‐AMS at a suburban site in Hong Kong during springtime 2011

Physical and chemical characterization of ambient aerosol by HR‐ToF‐AMS at a suburban site in Hong Kong during springtime 2011

Multi-Perspective Analysis and Spatiotemporal Mapping of Air Pollution Monitoring Data

Insights into factors affecting nitrate in PM2.5 in a polluted high NOx environment through hourly observations and size distribution measurements

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Insights into factors affecting nitrate in PM_2.5 in a polluted high NO_x environment through hourly observations and size distribution measurements