Variation in global chemical composition of PM 2.5 : emerging results from SPARTAN

The Surface PARTiculate mAtter Network (SPARTAN) is a long-term project that includes characterization of chemical and physical attributes of aerosols from filter samples collected worldwide. This paper discusses the ongoing efforts of SPARTAN to define and quantify major ions and trace metals found...

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Published in:Atmospheric chemistry and physics 2016-08, Vol.16 (15), p.9629-9653
Main Authors: Snider, Graydon, Weagle, Crystal L., Murdymootoo, Kalaivani K., Ring, Amanda, Ritchie, Yvonne, Stone, Emily, Walsh, Ainsley, Akoshile, Clement, Anh, Nguyen Xuan, Balasubramanian, Rajasekhar, Brook, Jeff, Qonitan, Fatimah D., Dong, Jinlu, Griffith, Derek, He, Kebin, Holben, Brent N., Kahn, Ralph, Lagrosas, Nofel, Lestari, Puji, Ma, Zongwei, Misra, Amit, Norford, Leslie K., Quel, Eduardo J., Salam, Abdus, Schichtel, Bret, Segev, Lior, Tripathi, Sachchida, Wang, Chien, Yu, Chao, Zhang, Qiang, Zhang, Yuxuan, Brauer, Michael, Cohen, Aaron, Gibson, Mark D., Liu, Yang, Martins, J. Vanderlei, Rudich, Yinon, Martin, Randall V.
Format: Article
Language:English
Subjects:
Aerosol optical depth
Aerosol Robotic Network
Aerosols
Aluminum
Ammonium
Ammonium compounds
Ammonium nitrate
Anthropogenic factors
Atmospheric particulates
Black carbon
Chemical composition
Coefficient of variation
Components
Dry season
Dust storms
Environmental monitoring
Equivalence
Gravimetry
Humidity
Hygroscopicity
Instruments
Mathematical analysis
Monitoring instruments
National parks
Nephelometers
Optical analysis
Oxides
Particulate emissions
Particulate matter
Particulates
Photometers
Population density
Ratios
Relative humidity
Salts
Spatial distribution
Sulfates
Suspended particulate matter
Temporal variability
Temporal variations
Trace elements
Trace metals
Urban areas
Water purification
Zinc
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Summary:The Surface PARTiculate mAtter Network (SPARTAN) is a long-term project that includes characterization of chemical and physical attributes of aerosols from filter samples collected worldwide. This paper discusses the ongoing efforts of SPARTAN to define and quantify major ions and trace metals found in fine particulate matter (PM2.5). Our methods infer the spatial and temporal variability of PM2.5 in a cost-effective manner. Gravimetrically weighed filters represent multi-day averages of PM2.5, with a collocated nephelometer sampling air continuously. SPARTAN instruments are paired with AErosol RObotic NETwork (AERONET) sun photometers to better understand the relationship between ground-level PM2.5 and columnar aerosol optical depth (AOD).We have examined the chemical composition of PM2.5 at 12 globally dispersed, densely populated urban locations and a site at Mammoth Cave (US) National Park used as a background comparison. So far, each SPARTAN location has been active between the years 2013 and 2016 over periods of 2–26 months, with an average period of 12 months per site. These sites have collectively gathered over 10 years of quality aerosol data. The major PM2.5 constituents across all sites (relative contribution ± SD) are ammoniated sulfate (20 % ± 11 %), crustal material (13.4 % ± 9.9 %), equivalent black carbon (11.9 % ± 8.4 %), ammonium nitrate (4.7 % ± 3.0 %), sea salt (2.3 % ± 1.6 %), trace element oxides (1.0 % ± 1.1 %), water (7.2 % ± 3.3 %) at 35 % RH, and residual matter (40 % ± 24 %).Analysis of filter samples reveals that several PM2.5 chemical components varied by more than an order of magnitude between sites. Ammoniated sulfate ranges from 1.1 µg m−3 (Buenos Aires, Argentina) to 17 µg m−3 (Kanpur, India in the dry season). Ammonium nitrate ranged from 0.2 µg m−3 (Mammoth Cave, in summer) to 6.8  µg m−3 (Kanpur, dry season). Equivalent black carbon ranged from 0.7 µg m−3 (Mammoth Cave) to over 8 µg m−3 (Dhaka, Bangladesh and Kanpur, India). Comparison of SPARTAN vs. coincident measurements from the Interagency Monitoring of Protected Visual Environments (IMPROVE) network at Mammoth Cave yielded a high degree of consistency for daily PM2.5 (r2 = 0.76, slope  =  1.12), daily sulfate (r2 = 0.86, slope  =  1.03), and mean fractions of all major PM2.5 components (within 6 %). Major ions generally agree well with previous studies at the same urban locations (e.g. sulfate fractions agree within 4 % for 8 out of 11 collocation comparisons). Enh
ISSN:1680-7324
1680-7316
1680-7324
DOI:10.5194/acp-16-9629-2016