Atmospheric Environment 143 (2016) 300e312
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A field measurement based scaling approach for quantification of major ions, organic carbon, and elemental carbon using a single particle aerosol mass spectrometer Yang Zhou a, b, X.H. Hilda Huang a, Stephen M. Griffith c, Mei Li d, *, Lei Li d, Zhen Zhou d, Cheng Wu e, Junwang Meng e, Chak K. Chan e, f, g, Peter K.K. Louie h, Jian Zhen Yu c, e, ** a
Institute of Environment, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China Key Laboratory of Physical Oceanography, College of Oceanic and Atmospheric Sciences, Ocean University of China, Qingdao 266100, China Department of Chemistry, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China d Institute of Atmospheric Environment Safety and Pollution Control, Jinan University, Guangzhou 510632, Guangdong, China e Division of Environment, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China f Department of Chemical and Biomolecular Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China g School of Energy and Environment, City University of Hong Kong, Kowloon, Hong Kong, China h Hong Kong Environmental Protection Department, Wan Chai, Hong Kong, China b c
h i g h l i g h t s Developed several scaling procedures for SPAMS based on a field campaign datasets. Determined a set of correction parameters to link SPAMS data with the bulk measurements. Obtained improved correlation of ion intensity by SPAMS with bulk measurements of main PM2.5 components. SPAMS could underestimate Kþ under high influence of biomass burning emissions.
a r t i c l e i n f o
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Article history: Received 9 October 2015 Received in revised form 4 August 2016 Accepted 18 August 2016 Available online 21 August 2016
Single Particle Aerosol Mass Spectrometers (SPAMS) have been increasingly deployed for aerosol studies in Asia. To date, SPAMS is most often used to provide unscaled information for both the size and chemical composition of individual particles. The instrument's lack of accuracy is primarily due to only a fraction of particles being detected after collection, and the instrumental sensitivity is un-calibrated for various chemical species in mixed ambient aerosols. During a campaign from January to April 2013 at a coastal site in Hong Kong, the particle number information and ion intensity of major PM2.5 components collected by SPAMS were scaled by comparing with collocated bulk PM2.5 measurements of hourly or higher resolution. The bulk measurements include PM2.5 mass by a SHARP 5030 Monitor, major ions by a Monitor for Aerosols & Gases in ambient Air (MARGA), and organic carbon (OC) and elemental carbon (EC) by a Sunset OCEC analyzer. During the data processing, both transmission efficiency (scaled with the Scanning Mobility Particle Sizer) and hit efficiency conversion were considered, and component ion intensities quantified as peak area (PA) and relative peak area (RPA) were analyzed to track the performance. The comparison between the scaled particle mass assuming a particle density of 1.9 g cm3 from SPAMS and PM2.5 concentration showed good correlation (R2 ¼ 0.81) with a slope of 0.814 ± 0.004. Regression analysis results suggest an improved scaling performance using RPA compared with PA for most of the major PM2.5 components, including sulfate, nitrate, potassium, ammonium, OC and EC. Thus, we recommend preferentially scaling these species using the RPA. For periods of high Kþ concentrations (>1.5 mg m3), under-estimation of Kþ by SPAMS was observed due to exceeding the dynamic range of the acquisition board. When only applying the hit efficiency correction, data for sulfate, nitrate, ammonium, potassium and OC were in reasonably good correlation (R2 ¼ 0.56e0.79) with the bulk measurements, suggesting semi-quantified data by the hit efficiency correction can be utilized when
Keywords: Single particle PM2.5 Laser ionization Scaling factor Ions OCEC
* Corresponding author. ** Corresponding author. Division of Environment, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China. E-mail addresses:
[email protected] (M. Li),
[email protected] (J.Z. Yu). http://dx.doi.org/10.1016/j.atmosenv.2016.08.054 1352-2310/© 2016 Elsevier Ltd. All rights reserved.
Y. Zhou et al. / Atmospheric Environment 143 (2016) 300e312
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transmission efficiency correction is not available. More inter-comparisons of this type are needed to assess the inter-instrument variability among different SPAMS instruments. © 2016 Elsevier Ltd. All rights reserved.
1. Introduction Laser ablation/ionization methods can characterize individual particles in real-time performing a rapid analysis (
