Sampling and conditioning artifacts of PM2.5 in filter-based samplers

Liu, Chun Nan; Lin, Sih Fan; Awasthi, Amit; Tsai, Chuen-Tinn; Wu, Yueh Chuen; Chen, Chung Fang

doi:10.1016/j.atmosenv.2013.11.075

Cited by 48 publications

(17 citation statements)

References 25 publications

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“…PM 2.5 measured by the TEOM 1405 Monitor, which was much greater than the values of 50-60 % reported by previous studies in the NCP (Shen et al, 2009;. It was possible that the mass concentration of PM 2.5 measured by the TEOM 1405 Monitor was underestimated because the volatile even semi-volatile component in PM 2.5 can be easily lost at 50 • C which is designed in the TEOM 1405 Monitor for avoiding water condensation on the filter (Charron et al, 2004;Grover et al, 2005;C. N. Liu et al, 2014).…”

Section: Resultscontrasting

confidence: 48%

The possible contribution of the periodic emissions from farmers' activities in the North China Plain to atmospheric water-soluble ions in Beijing

Liu

Zhang

et al. 2016

Atmos. Chem. Phys.

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Abstract. The North China Plain (NCP), which includes Beijing, is currently suffering from severe haze events due to a high pollution level of PM 2.5 . To mitigate the serious pollution problem, identification of the sources of PM 2.5 is urgently needed for the effective control measures. Daily samples of PM 2.5 were collected in Beijing city and in a rural area in Baoding, Hebei Province through the year of 2014, and the seasonal variation of water-soluble ions (WSIs) in PM 2.5 was comprehensively analysed to determine their possible sources. The results indicated that the periodic emissions from farmers' activities made a significant contribution to the atmospheric WSIs in Beijing. The relatively high concentration of K + in winter and autumn at the two sampling sites confirmed that crop straw burning contributed to atmospheric K + in Beijing. The remarkable elevation of Cl − at the two sampling sites as well as the evident increase of the Cl − / K + ratio and the Cl − proportion in WSIs during the winter in Beijing could be ascribed to coal combustion for heating by farmers. The unusually high ratio of Cl − to Na + in summer, the obviously high concentrations of Cl − in the rural sampling site and the elevation of Cl − proportion in WSIs in Beijing during the maize fertilization could be explained by the use of the prevailing fertilizer of NH 4 Cl in the vast area of NCP. The abnormally high concentrations of Ca 2+ at the two sampling sites and the elevation of Ca 2+ proportion during the period of the maize harvest and soil ploughing in Beijing provided convincing evidence that the intensive agricultural activities in autumn contributed to the regional mineral dust. The most serious pollution episodes in autumn were coincident with significant elevation of Ca 2+ , indicating that the mineral dust emission from the harvest and soil ploughing not only increased the atmospheric concentrations of the primary pollutants, but also greatly accelerated formation of sulfate and nitrate through heterogeneous reactions of NO 2 and SO 2 on the mineral dust. The backward trajectories also indicated that the highest concentrations of WSIs usually occurred in the air parcel from southwest-south regions, which have a high density of farmers. In addition, the values of nitrogen oxidation ratio (NOR) and the sulfur oxidation ratio (SOR) were found to be much greater under haze days than under non-haze days, implying that formation of sulfate and nitrate was greatly accelerated through heterogeneous or multiphase reactions of NO 2 and SO 2 on PM 2.5 .

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Section: Resultscontrasting

confidence: 48%

The possible contribution of the periodic emissions from farmers' activities in the North China Plain to atmospheric water-soluble ions in Beijing

Liu

Zhang

et al. 2016

Atmos. Chem. Phys.

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“…Therefore, the volatilization of a material in the particulate phase on the Teflon filter should increase if that material in the gas phase is removed by the upstream denuder (Yu et al, 2006). However, as shown in Table 2, only VR of NO 3 -is positively correlated with HNO 3 concentration at the upstream denuder (p < 0.05) (Liu et al, 2014). Even VR of NO 3 -is more closely related to NH 3 concentration at the upstream denuder (p < 0.01), indicating that particulate NO 3 -on the Teflon filter is volatilized, because of the NH 3 deficiency (to form NH 4 NO 3 ) by removing NH 3 at the upstream denuder.…”

Section: Major Factors Affecting the Volatilization Ratiomentioning

confidence: 84%

Characterization of Volatilization of Filter-Sampled PM2.5 Semi-Volatile Inorganic Ions Using a Backup Filter and Denuders

Kim

Choi

Ghim

2015

Aerosol Air Qual. Res.

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The characteristics of the volatilization of semi-volatile inorganic ions sampled on a Teflon filter were investigated using a backup nylon filter and annular denuders. The volatilization ratio (VR) was defined as the fraction of the concentration at the backup filter and denuder to the sum of the concentrations collected at the Teflon filter, backup filter, and denuder. Particles whose aerodynamic diameters are less than or equal to 2.5 µm (PM 2.5 ) were sampled for 24 h each season from summer 2011 to spring 2012 at a site, about 35 km southeast of downtown Seoul. Increase in VR with increasing temperature was evident, but the effects of relative humidity were not clear, because seasonal variation in the two variables was correlated, and the variation in relative humidity was smaller than that in temperature. While VRs generally decreased with the amounts sampled on the Teflon filter, details of the volatilization behaviors varied among ions according to concentrations at the Teflon filter and VR. The removal of gaseous species at the upstream denuders affected VRs of semi-volatile ions by shifting the equilibrium among NH 4 + , NO 3 -, and SO 4 2-.

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“…Further, HEPA filter tests will be carried out to prove the breakthrough of NH 3 after few days of use of the denuder. Although the Cl ¡ correlation can also be described as good, the increased variability could be due to either the high and variable content of Cl ¡ on quartz filters (Wieprechta et al 2004) or loss of volatile NH 4 Cl (Witz et al 1990;Liu et al 2014). The discrepancy between the two methods is larger toward the end of year, where high values of Cl ¡ were found on the filters as consequence of high concentrations of sea-spray in air.…”

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confidence: 98%

A Comparison Between a Semi-Continuous Analyzer and Filter-Based Method for Measuring Anion and Cation Concentrations in PM₁₀at an Urban Background Site in London

Beccaceci

McGhee

Brown

et al. 2015

Aerosol Science and Technology

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A comparison between the filter-based, laboratory ion chromatography technique and a semi-continuous analyzer (URG 9000B Ambient Ion Monitor [AIM]) was conducted to evaluate the performance of the AIM in measuring the concentrations of the main airborne ionic species in PM 10 . The study was carried out in an urban background area of London (UK) in 2013. The two methods showed an overall good correlation (R 2 > 0.83) for nitrate, sulfate, chloride, ammonium, and magnesium and poor correlation was found for sodium, potassium, and calcium (R 2 < 0.50). The AIM gave consistently higher concentrations for sodium and potassium, possibly due to a positive bias within the sampling unit. During high concentration episodes, both the efficiency of the particle extraction and removal of gases by the denuder may be reduced. A HEPA filter test demonstrated that the denuder was removing gaseous components effectively but that there was some potential for contamination. Overall, the AIM was found to be a good instrument for measuring hourly anion and cation concentrations in PM 10 in urban sites.

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Sampling and conditioning artifacts of PM2.5 in filter-based samplers

Cited by 48 publications

References 25 publications

The possible contribution of the periodic emissions from farmers' activities in the North China Plain to atmospheric water-soluble ions in Beijing

The possible contribution of the periodic emissions from farmers' activities in the North China Plain to atmospheric water-soluble ions in Beijing

Characterization of Volatilization of Filter-Sampled PM2.5 Semi-Volatile Inorganic Ions Using a Backup Filter and Denuders

A Comparison Between a Semi-Continuous Analyzer and Filter-Based Method for Measuring Anion and Cation Concentrations in PM₁₀at an Urban Background Site in London

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Sampling and conditioning artifacts of PM2.5 in filter-based samplers

Cited by 48 publications

References 25 publications

The possible contribution of the periodic emissions from farmers' activities in the North China Plain to atmospheric water-soluble ions in Beijing

The possible contribution of the periodic emissions from farmers' activities in the North China Plain to atmospheric water-soluble ions in Beijing

Characterization of Volatilization of Filter-Sampled PM2.5 Semi-Volatile Inorganic Ions Using a Backup Filter and Denuders

A Comparison Between a Semi-Continuous Analyzer and Filter-Based Method for Measuring Anion and Cation Concentrations in PM10at an Urban Background Site in London

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Product

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A Comparison Between a Semi-Continuous Analyzer and Filter-Based Method for Measuring Anion and Cation Concentrations in PM₁₀at an Urban Background Site in London