Unraveling the role of silicon in atmospheric aerosol secondary formation: a new conservative tracer for aerosol chemistry

Lu, Dawei; Tan, Jihua; Yang, Xuezhi; Sun, Xu; Liu, Qian; Jiang, Guibin

Aerosol particles are ubiquitous in the atmosphere and affect the quality of human life through their climatic and health effects. The formation and growth of aerosol particles involve extremely complex reactions and processes. Due to limited research tools, the sources and chemistry of aerosols are still not fully understood, and until now have normally been investigated by using chemical species of secondary aerosols (e.g., inline-formula M1inlinescrollmathml chem normal NH normal 4 + 24pt15ptsvg-formulamathimg8aeb386a576ed6c8280ae774099f80e4 acp-19-2861-2019-ie00001.svg24pt15ptacp-19-2861-2019-ie00001.png , inline-formula M2inlinescrollmathml chem normal NO normal 3 - 25pt16ptsvg-formulamathimg4c315b3ea451cf26923ad12993612b33 acp-19-2861-2019-ie00002.svg25pt16ptacp-19-2861-2019-ie00002.png , inline-formula M3inlinescrollmathml chem normal SO normal 4 normal 2 - 29pt17ptsvg-formulamathimg6060a0eb6022af681aa55d19b3180df9 acp-19-2861-2019-ie00003.svg29pt17ptacp-19-2861-2019-ie00003.png , SOC) as tracers. Here we investigated the role of silicon (Si), an ubiquitous but relatively inert element, during the secondary aerosol formation process. We analyzed the correlation of Si in airborne fine particles (inline-formulaPM2.5) collected in Beijing – a typical pollution region – with the secondary chemical species and secondary particle precursors (e.g., inline-formulaSO2 and inline-formulaNOx). The total mass of Si in inline-formulaPM2.5 was found to be uncorrelated with the secondary aerosol formation process, which suggested that Si is a new conservative tracer for the amount of primary materials in inline-formulaPM2.5 and can be used to estimate the relative amount of secondary and primary compounds in inline-formulaPM2.5. This finding enables the accurate estimation of secondary aerosol contribution to inline-formulaPM2.5 by using Si as a single tracer rather than the commonly used multiple chemical tracers. In addition, we show that the correlation analysis of secondary aerosols with the Si isotopic composition of inline-formulaPM2.5 can further reveal the sources of the precursors of secondary aerosols. Therefore, Si may provide a new tool for aerosol chemistry studies.



Lu, Dawei / Tan, Jihua / Yang, Xuezhi / et al: Unraveling the role of silicon in atmospheric aerosol secondary formation: a new conservative tracer for aerosol chemistry. 2019. Copernicus Publications.


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