10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
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Source Apportionment of High Resolution Aerosol Trace Elements in Beijing, China
P. RAI, Markus Furger, Jay G. Slowik, Francesco Canonaco, Rujin Huang, Junji Cao, Urs Baltensperger, Andre S.H. Prévôt, Paul Scherrer Institute
Abstract Number: 916 Working Group: Source Apportionment
Abstract In the context of rapid economic development and industrial growth in Asian countries, particularly in China, anthropogenic emissions into the atmosphere have had a drastic increase in recent years. Heavily urbanized areas are characterized by a wide array of particle sources, which must be quantified for the formulation of efficient pollution mitigation strategies. Receptor modeling of high resolution data and near real time measurements of trace elements adds greater temporal variabilities to certain source apportionment analyses, which can assist in the identification of local anthropogenic sources such as traffic and industries.
Here we present source apportionment of highly time resolved and near real time measurements of trace metals in Beijing, China during winter time (November/December 2017). During the campaign PM10 and PM2.5 were sampled with 1-hour time resolution alternatively by an Xact® 625i ambient metals monitor. Sources were resolved using the multilinear engine (ME-2) implementation of positive matrix factorization (Paatero, 1999; Canonaco et al 2013).
The sampling site in Beijing was located in the north of the urban core with two main roads at about 800 m in south and west directions. We found five sources in both size fractions, mineral dust, traffic, S-rich and regional background sources, like industrial and coal combustion, derived from ME-2 analysis. Mineral dust elements (e.g. Al, Si, Ca, Ti, Fe, V) are elevated through the day (2-3 times higher than at night), suggesting their concentrations are driven by resuspension due to anthropogenic activities. While there is no strong diurnal patterns for S-rich, coal combustion and industrial elements (e.g. Cl, Ni, Co, Zn) indicate more diffuse sources. In addition to the sources resolved in both size ranges, we find (size-dependent) evidence for biomass burning and metal smelters emissions. Traffic-related elements (e.g. Cu, Sb, Cr, Ba, Fe, Sn, Zr, Mn) in both size ranges show prominent peaks during the morning and evening rush hours, as is typically the case for traffic-related pollutants similar to NOx and CO. Both size ranges show distinguish maxima peaks during morning and evening hours. The strong night peak in PM2.5 size fraction might be related to truck activity, which is enhanced during the night hours as truck activity is banned during the day. We will discuss source identification, quantification, and contributions to total PM at this sampling site.
Acknowledgements This project was supported by the Swiss National Science Foundation project 200021_162448.