Collocated speciation of PM2.5 using tandem quartz filters in northern nanjing, China: Sampling artifacts and measurement uncertainty. (1st February 2021)

• Record Type: Journal Article
• Authors: Yang, Li; Shang, Yue; Hannigan, Michael P.; Zhu, Rui; Wang, Qin'geng; Qin, Chao; Xie, Mingjie
• Is Part Of: Atmospheric environment. Volume 246(2021)
• Publication Date: 2021-02-01
• Subjects: PM2.5 -- Quartz filter -- Collocated sampling -- Artifact -- Uncertainty; Air -- Pollution -- Periodicals; Air -- Pollution -- Meteorological aspects -- Periodicals; 551.51
• DOI: 10.1016/j.atmosenv.2020.118066
• Languages: English
• ISSNs: 1352-2310

Abstract

Abstract: In this study, collocated samples of particulate matter with aerodynamic diameter less than 2.5 μm (PM2.5 ) were collected every sixth day on quartz filters (Q f ) at a suburban site in northern Nanjing, China for one year. A backup quartz filter (Q b ) was installed behind Q f to estimate positive artifacts. The analysis of gravimetric mass, water-soluble inorganic ions (WSIIs), total organic (OC) and elemental carbon (EC), water-soluble OC (WSOC), total nitrogen (WSTN) and organic nitrogen (WSON) were performed on both Q f and Q b . Due to the high mass loadings on Q f (17.9 ± 7.82 mg filter −1, 4.71–38.5 mg filter −1 ), the collocated precision of gravimetric mass and dominant species (NH4 +, NO3 −, SO4 2−, OC, and EC) is better than that from previous work. Except K +, EC, and WSON, all other target components were detected on Q b with average Q b /Q f ratios ranging from 3.02 ± 3.48–21.7 ± 22.4%. The final concentrations and uncertainties of PM2.5 components were determined based on duplicate Q f –Q b data. The results suggest that using an error fraction of 10% will underestimate the uncertainty of less concentrated species (e.g., Ca 2+ and Mg 2+ ) in PM2.5 . Due to the evaporation loss of semi-volatile materials from the Q f, the Q f –Q b calculation would lead to an estimate of the lower limit for particulate NH4 +, NO3 −, and OC. Synchronized hourly data of PM2.5 mass and components were obtained at downtown Nanjing. The comparisons of gravimetric versus reconstructed PM2.5 and filter-based versus continuous measurements of PM2.5 components indicate that a substantial fraction of the unexplained gravimetric PM2.5 can be attributed to aerosol water. Graphical abstract: Image 1 Highlights: Collocated precision of PM2.5 components depends largely on filter loadings. Besides OC adsorption, quartz filter sampling is also subject to surface reactions. Assuming a constant error fraction of 10% is appropriate for PM2.5 major components. Water content contributes a substantial fraction of the unexplained gravimetric PM2.5 .