Isotopic constraints on heterogeneous sulphate production in Beijing haze

He, Pengzhen; Alexander, Becky; Geng, Lei; Chi, Xiaowei; Fan, Shidong; Zhan, Haicong; Kang, Hui; Zheng, Guangjie; Cheng, Yafang; Su, Hang; Liu, Cheng; Xie, Zhouqing

doi:10.5194/acp-2017-977

Cited by 3 publications

(4 citation statements)

References 15 publications

(20 reference statements)

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“…It is essential to note that the revised ISORROPIA when running in the stable state yields an almost identical distribution as compared to ISORROPIA in the metastable state. The studies using the standard ISORROPIA model with the stable state assumption have predicted unrealistic pH values of around 7 and should be reevaluated He et al, 2017). Previous ISORROPIA calculations using the metastable state assumption 15 obtained average pH values from 4.1 to 5.4 (He et al, 2017;Liu et al, 2017a;Shi et al, 2017;Cheng et al, 2016;Guo et al, 2017b;Tan et al, 2018), agreeing reasonably with our results (an average pH value of 4.6).…”

Section: Summary Of Existing Studiessupporting

confidence: 81%

“…The studies using the standard ISORROPIA model with the stable state assumption have predicted unrealistic pH values of around 7 and should be reevaluated He et al, 2017). Previous ISORROPIA calculations using the metastable state assumption 15 obtained average pH values from 4.1 to 5.4 (He et al, 2017;Liu et al, 2017a;Shi et al, 2017;Cheng et al, 2016;Guo et al, 2017b;Tan et al, 2018), agreeing reasonably with our results (an average pH value of 4.6). It is noted that concentrations of Ca 2+ and Mg 2+ were not measured in this study and a sensitivity test suggests that including these crustal cations in thermodynamic calculations would increase predicted pH values by about 0.1 unit (Fig.…”

Section: Summary Of Existing Studiessupporting

confidence: 81%

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Fine particle pH for Beijing winter haze as inferred from different thermodynamic equilibrium models

Song¹,

Gao²,

Xu³

et al. 2018

Preprint

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Abstract. pH is an important property of aerosol particles but is difficult to measure directly. Several studies have estimated the pH values for fine particles in North China winter haze using thermodynamic models (i.e., E-AIM and ISORROPIA) and ambient measurements. The reported pH values differ widely, ranging from close to 0 (highly acidic) to as high as 7 (neutral).In order to understand the reason for this discrepancy, we calculated pH values using these models with different assumptions 25 with regard to model inputs and particle phase states. We find that the large discrepancy is due primarily to differences in the model assumptions adopted in previous studies. Calculations using only aerosol phase composition as inputs (i.e., reverse mode) are sensitive to the measurement errors of ionic species and inferred pH values exhibit a bimodal distribution with peaks between −2 and 2 and between 7 and 10. Calculations using total (gas plus aerosol phase) measurements as inputs (i.e., forward mode) are affected much less by the measurement errors, and results are thus superior to those obtained from the reverse mode 30 calculations. Forward mode calculations in this and previous studies collectively indicate a moderately acidic condition (pH from about 4 to about 5) for fine particles in North China winter haze, indicating further that ammonia plays an important role in determining this property. The differences in pH predicted by the forward mode E-AIM and ISORROPIA calculations may be attributed mainly to differences in estimates of activity coefficients for hydrogen ions. The phase state assumed, which can be either stable (solid plus liquid) or metastable (only liquid), does not significantly impact pH predictions of ISORROPIA. 35Atmos. Chem. Phys. Discuss., https://doi

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Section: Summary Of Existing Studiessupporting

confidence: 81%

Section: Summary Of Existing Studiessupporting

confidence: 81%

Fine particle pH for Beijing winter haze as inferred from different thermodynamic equilibrium models

Song¹,

Gao²,

Xu³

et al. 2018

Preprint

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“…However, recent studies have shown that the oxidation pathways of SO 2 represented in AM3, e.g., homogeneous oxidation by OH and aqueous oxidation by O 3 and H 2 O 2 , can not sustain the observed concentrations of sulfate in the North China Plains (Wang et al, 2014a;Zheng et al, 2015). Under hazy conditions, heterogeneous oxidation of SO 2 by NO 2 (Cheng et al, 2016) or O 2 (Hung and Hoffmann, 2015) at the surface of or in aerosols may be the dominant sources of SO 2− 4 , although the relative importance of these pathways remains uncertain (Guo et al, 2017;He et al, 2017). In order to quantify the sensitivity of our results to these reactions, we perform an additional simulation using the parameterization of the uptake coefficient of SO 2 on aerosols derived by Zheng et al (2015): Fig.…”

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confidence: 99%

Changes in the aerosol direct radiative forcing from 2001 to 2015: observational constraints and regional mechanisms

Paulot

Paynter

Ginoux

et al. 2018

Preprint

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Abstract. We present observation and model-based estimates of the changes in the direct shortwave effect of aerosols under clear-sky (SDRECS) from 2001 to 2015. Observation-based estimates are obtained from changes in the outgoing shortwave clear-sky radiation (Rsutcs) measured by the Clouds and the Earth's Radiant Energy System (CERES), accounting for the effect of variability in surface albedo, water vapor, and ozone. We find increases in SDRECS (i.e., less radiation scattered to space by aerosols) over Western Europe (0.7&#8211;1&#8201;W&#8201;m&#8722;2&#8201;dec&#8722;1) and the Eastern US (0.9&#8211;1.8&#8201;W&#8201;m&#8722;2&#8201;dec&#8722;1), decreases over India (&#8722;0.5&#8211;&#8201;&#8722;1.9&#8201;W&#8201;m&#8722;2&#8201;dec&#8722;1) and no significant change over Eastern China. Comparisons with the GFDL chemistry climate model AM3, driven by CMIP6 historical emissions, show that changes in SDRECS over Western Europe and the Eastern US are well captured, which largely reflects the mature understanding of the sulfate budget in these regions. In contrast, the model overestimates the trends in SDRECS over India and Eastern China. Over China, this bias can be partly attributed to the decline of SO2 emissions after 2007, which is not captured by the CMIP6 emissions. In both India and Eastern China, we find much larger contributions of nitrate and black carbon to changes in SDRECS than in the US and Europe, which highlights the need to better constrain their precursors and chemistry. Globally, our model shows that changes in the all-sky aerosol direct forcing between 2001 and 2015 (+0.03&#8201;W&#8201;m&#8722;2) are dominated by black carbon (+0.12&#8201;W&#8201;m&#8722;2) with significant offsets from nitrate (&#8722;0.03&#8201;W&#8201;m&#8722;2) and sulfate (&#8722;0.03&#8201;W&#8201;m&#8722;2). Changes in the sulfate (+7&#8201;%) and nitrate (+60&#8201;%) all-sky direct forcing between 2001 and 2015 are only weakly related to changes in the emissions of their precursors (&#8722;12.5&#8201;% and 19&#8201;% for SO2 and NH3, respectively), due mostly to chemical non linearities.

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“…Full methodological details are given in He et al. (2018). In summary, a punch sample of each filter was extracted via sonication and filtered through pre‐washed 0.22‐µm filters.…”

Section: Methodsmentioning

confidence: 99%

Spatial and Temporal Distribution of Sea Salt Aerosol Mass Concentrations in the Marine Boundary Layer From the Arctic to the Antarctic

Jiang

Xie

et al. 2021

JGR Atmospheres

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Isotopic constraints on heterogeneous sulphate production in Beijing haze

Cited by 3 publications

References 15 publications

Fine particle pH for Beijing winter haze as inferred from different thermodynamic equilibrium models

Fine particle pH for Beijing winter haze as inferred from different thermodynamic equilibrium models

Changes in the aerosol direct radiative forcing from 2001 to 2015: observational constraints and regional mechanisms

Spatial and Temporal Distribution of Sea Salt Aerosol Mass Concentrations in the Marine Boundary Layer From the Arctic to the Antarctic

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