Preprints
https://doi.org/10.5194/egusphere-2023-311
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/egusphere-2023-311
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
21 Mar 2023
| 21 Mar 2023
Iodine oxoacids and their roles in sub-3 nanometer particle growth in polluted urban environments
Ying Zhang
Aerosol and Haze Laboratory, Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing, China
Joint International Research Laboratory of Atmospheric and Earth System Sciences, School of Atmospheric Sciences, Nanjing University, Nanjing, China
Jiangsu Provincial Collaborative Innovation Center of Climate Change, Nanjing, China
Duzitian Li
Joint International Research Laboratory of Atmospheric and Earth System Sciences, School of Atmospheric Sciences, Nanjing University, Nanjing, China
Jiangsu Provincial Collaborative Innovation Center of Climate Change, Nanjing, China
Institute for Atmospheric and Earth System/Physics, Faculty of Science, University of Helsinki, Helsinki, Finland
Finnish Meteorological Institute, Helsinki, Finland
Wei Nie
CORRESPONDING AUTHOR
Joint International Research Laboratory of Atmospheric and Earth System Sciences, School of Atmospheric Sciences, Nanjing University, Nanjing, China
Jiangsu Provincial Collaborative Innovation Center of Climate Change, Nanjing, China
Chenjuan Deng
State Key Joint Laboratory of Environment Simulation and Pollution Control, State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex, School of Environment, Tsinghua University, Beijing, China
Runlong Cai
Institute for Atmospheric and Earth System/Physics, Faculty of Science, University of Helsinki, Helsinki, Finland
Yuliang Liu
Joint International Research Laboratory of Atmospheric and Earth System Sciences, School of Atmospheric Sciences, Nanjing University, Nanjing, China
Jiangsu Provincial Collaborative Innovation Center of Climate Change, Nanjing, China
Yishuo Guo
Aerosol and Haze Laboratory, Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing, China
Chong Liu
Joint International Research Laboratory of Atmospheric and Earth System Sciences, School of Atmospheric Sciences, Nanjing University, Nanjing, China
Jiangsu Provincial Collaborative Innovation Center of Climate Change, Nanjing, China
Yiran Li
State Key Joint Laboratory of Environment Simulation and Pollution Control, State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex, School of Environment, Tsinghua University, Beijing, China
Liangduo Chen
Joint International Research Laboratory of Atmospheric and Earth System Sciences, School of Atmospheric Sciences, Nanjing University, Nanjing, China
Jiangsu Provincial Collaborative Innovation Center of Climate Change, Nanjing, China
Yuanyuan Li
Joint International Research Laboratory of Atmospheric and Earth System Sciences, School of Atmospheric Sciences, Nanjing University, Nanjing, China
Jiangsu Provincial Collaborative Innovation Center of Climate Change, Nanjing, China
Chenjie Hua
Aerosol and Haze Laboratory, Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing, China
Tingyu Liu
Aerosol and Haze Laboratory, Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing, China
Zongcheng Wang
Aerosol and Haze Laboratory, Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing, China
Lei Wang
Joint International Research Laboratory of Atmospheric and Earth System Sciences, School of Atmospheric Sciences, Nanjing University, Nanjing, China
Jiangsu Provincial Collaborative Innovation Center of Climate Change, Nanjing, China
Tuukka Petäjä
Institute for Atmospheric and Earth System/Physics, Faculty of Science, University of Helsinki, Helsinki, Finland
Federico Bianchi
Institute for Atmospheric and Earth System/Physics, Faculty of Science, University of Helsinki, Helsinki, Finland
Ximeng Qi
Joint International Research Laboratory of Atmospheric and Earth System Sciences, School of Atmospheric Sciences, Nanjing University, Nanjing, China
Jiangsu Provincial Collaborative Innovation Center of Climate Change, Nanjing, China
Xuguang Chi
Joint International Research Laboratory of Atmospheric and Earth System Sciences, School of Atmospheric Sciences, Nanjing University, Nanjing, China
Jiangsu Provincial Collaborative Innovation Center of Climate Change, Nanjing, China
Pauli Paasonen
Institute for Atmospheric and Earth System/Physics, Faculty of Science, University of Helsinki, Helsinki, Finland
Yongchun Liu
Aerosol and Haze Laboratory, Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing, China
Joint International Research Laboratory of Atmospheric and Earth System Sciences, School of Atmospheric Sciences, Nanjing University, Nanjing, China
Jiangsu Provincial Collaborative Innovation Center of Climate Change, Nanjing, China
Jingkun Jiang
State Key Joint Laboratory of Environment Simulation and Pollution Control, State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex, School of Environment, Tsinghua University, Beijing, China
Aijun Ding
Joint International Research Laboratory of Atmospheric and Earth System Sciences, School of Atmospheric Sciences, Nanjing University, Nanjing, China
Jiangsu Provincial Collaborative Innovation Center of Climate Change, Nanjing, China
Markku Kulmala
Aerosol and Haze Laboratory, Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing, China
Joint International Research Laboratory of Atmospheric and Earth System Sciences, School of Atmospheric Sciences, Nanjing University, Nanjing, China
Jiangsu Provincial Collaborative Innovation Center of Climate Change, Nanjing, China
Institute for Atmospheric and Earth System/Physics, Faculty of Science, University of Helsinki, Helsinki, Finland
Abstract. New particle formation processes contribute significantly to the number concentration of ultrafine particles (UFP), and have great impacts on human health and global climate. Iodine oxoacids (HIOx, including iodic acid, HIO3 and iodous acid, HIO2) have been observed in pristine regions and proved to dominate NPF events at some sites. However, the knowledge of HIOx in polluted urban areas is rather limited. Here, we conducted a long-term comprehensive observation of gaseous iodine oxoacids and sulfuric acid in Beijing from January 2019 to October 2021 and also in Nanjing from March 2019 to February 2020, and investigated the contribution of HIOx to UFP number concentration in urban environments. HIO3 concentration is highest in summer, up to 2.85×106 cm-3 and 2.78×106 cm-3 in Beijing and Nanjing, respectively, and is lowest in winter, with a more prominent seasonal variation than H2SO4. HIO3 concentration shows a clear diurnal pattern at both sites with a daily maximum at around noontime, similar to the atmospheric temperature, radiation and ozone (O3) levels. HIO2 concentration has the same diurnal and seasonal trend as HIO3 but is overall about one order of magnitude lower than HIO3 concentration. Back trajectory analysis suggests that the sources for inland iodine species could be a mix of marine and terrestrial origins, both having peak iodine emission in warm seasons. While the contribution of HIO2 to particle growth is marginal in Beijing and Nanjing, our results demonstrate that HIO3 enhances the particle survival probability of sub-3 nm particles by about 40 % (median) and occasionally by more than 100 % in NPF events, suggesting HIOx are non-negligible contributor to UFPs in polluted urban areas. As the growth contribution from HIO3 and H2SO4 is similar on a per-molecule basis, we propose that the sum of HIO3 and H2SO4 could be used to estimate sub-3 nm particle growth of inorganic acid origin, in the polluted atmospheres with a significant amount of HIOx.
How to cite. Zhang, Y., Li, D., He, X.-C., Nie, W., Deng, C., Cai, R., Liu, Y., Guo, Y., Liu, C., Li, Y., Chen, L., Li, Y., Hua, C., Liu, T., Wang, Z., Wang, L., Petäjä, T., Bianchi, F., Qi, X., Chi, X., Paasonen, P., Liu, Y., Yan, C., Jiang, J., Ding, A., and Kulmala, M.: Iodine oxoacids and their roles in sub-3 nanometer particle growth in polluted urban environments, EGUsphere [preprint], https://doi.org/10.5194/egusphere-2023-311, 2023.
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Ying Zhang et al.
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RC1: 'Comment on egusphere-2023-311', Anonymous Referee #1, 07 Aug 2023
This study reports unique long-term CIMS measurements of HIOx as well as NPF events in two urban areas, Beijing and Nanjing, China. The source analysis of iodic acid indicated potential long-range transport from marine and terrestrial sources rather than local anthropogenic emissions. They also estimated the contribution of HIOx and H2SO4 to nanoparticle growth rate and survival probability of nanoparticles. This paper shows that, although iodic acid does not play a major role in nanoparticle growth rate, the additional growth by iodic acid can enhance the survival of sub-3 nm particles in Beijing during NPF events. This suggests iodic acid contributes to NPF events in urban conditions with support from field measurements. However, some technical details on the measurement and analysis need to be clarified. Therefore, I recommend the manuscript for publication after revisions to address my comments below.
Main comments:
- Eq. (9) & (11): What was the range of temperature/size correction factor applied to GR(HIO3) in eq. (9)? Also, please explain why GR(H2SO4) in eq. (11) does not need temperature correction. In eq. (5), GR is corrected only to account for growth by condensation. And it is unclear in the text whether GR(HIO3) and GR(H2SO4) in those equations are growth rates only by condensation (excluding coagulation).
- Line 273-274: “We define SPtot as the particle survival probability calculated using the measured GRs (in Beijing) or the expected growth rate considering growth contributions from both H2SO4 and HIO3 (in Nanjing).” Please explain how using different inputs for SPtot calculation would affect EF in each site.
- Line 305-306: “The calibrated HIOx concentration is above the detection limit during almost the entire measurement periods…” However, I can not find more details on the calibration, except for the general description of nitrate CIMS in section 2.1.2. Therefore, the quantification method of HIOx (as well as H2SO4) needs to be shown and the sources of uncertainty need to be discussed since HIOx concentrations are being used for the growth rate and survival probability calculations. How and how often were the instruments calibrated for HIOx? Do authors expect losses in the sampling line or variations of HIOx sensitivity due to changes in temperature/relative humidity?
- Line 426: “implies that marine iodine sources could be important” Could it be emissions from industrial areas along with the back trajectory path?
- Line 428: That is the opposite direction of continental outflow.
- Line 445: Even if the HIO3 emission (or secondary formation) is higher in winter (when PM2.5 loading is higher), still the concentration of HIO3 can be lower due to potentially higher CS. Thus the y-axis in Fig.3 can be normalized by CS to see if the source of HIO3 is correlated to PM2.5 pollution.
- Line 522-529: Survival parameter (P) is newly introduced here and it is unclear why P is being used for AHL/BUCT case while survival probability (SP) is used for the rest of the analysis. Please compare the survival parameter from Kulmala et al. (2017) and survival probability (SP) from Lehtinen et al. (2007) and explain why using P is useful here.
- Line 567: “a fixed GR enhancement” What does “fixed” mean?
- Line 570-575: Are the MOD, APT-x, and APT-y methods equally credible? Then the differences in those methods represent the uncertainty of using MOD fitting method? Or do APT-x and APT-y represent upper/lower limit of MOD fitting?
- Line 586-588: “This is based on the observed consistency between the gaseous H2SO4 concentration and its significant contribution to the sub-3 nm particle growth rate in Beijing (Deng et al., 2020b).” However, in this study (Table S4), GR1.5-3 was generally higher than GR(H2SO4) in Beijing indicating contributions from other species.
- Fig. 5: In my understanding of the text, although HIO3 is not the major contributor in the measured GR, the sub 3-nm SP is so sensitive to additional GR from HIO3 that the additional HIO3 enhances SP of sub 3-nm significantly (as shown in fig. 7). And fig. 5 is a nice place to visually indicate that sensitive regimes that correspond to the data in fig. 7.
- Line 606-608: “As depicted in Fig. S8(c), SP enhancements in percentage are generally one order of magnitude higher than the GR contribution in percentage and HIO3 can result in as high as 2-fold enhancement on SP in sub-3 nm particle growth.” How important is the ~100% (or ~40% on average) enhancement of SP from HIO3 in the occurrence of NPF event? In Table S4, during NPF events in Beijing, the survival probability (“P1”) of sub 3-nm particles spans over 3 orders of magnitude from 6.1E-4 to 2.1E-1. Also, that wide range of SP needs to be directly mentioned in the main text.
Technical comments:
- Line 94: “survival probability (Kulmala et al., 2017)...” According to the rest of the text, the survival parameter is from Kulmala et al. (2017) and the survival probability is from Lehtinen et al. (2007).
- Line 250: GR’(HIO3) -> GR(HIO3).
- Line 269: Define dpinitial and dpfinal.
- Line 594: “IA” and ”SA” not defined previously (supposedly HIO3 and H2SO4?). Use consistent names in the main text and SI unless otherwise needed.
- Fig. 1&6: Make the panels bigger.
- Table S8 and S9 caption typo: SOREPS -> SORPES.
- Table S2-S7 & S9: Please use the consistent notations for survival probability (SP) and enhancement factor (EF) rather than “P” and “E”. Especially, “P” was used for the survival parameter in the main text and Fig. S6.
- Fig S4: The back trajectory color scheme is not consistent. Also, specify the meaning of (%) that the colors represent in the caption.
Citation: https://doi.org/10.5194/egusphere-2023-311-RC1 - RC2: 'Comment on egusphere-2023-311', Anonymous Referee #2, 29 Sep 2023
Ying Zhang et al.
Ying Zhang et al.
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Short summary
In this study, a long-term observation of gaseous iodine oxoacids has been carried out in two Chinese mega-cities. We find that iodine oxoacids ubiquitously present in these cities with the highest concentrations (up to 0.1 parts per trillion by volume) in summer. Our analysis shows that the iodine source is likely a mix of terrestrial and marine sources. Iodic acid is further found to contribute to sub-3 nanometer particle growth and particle survival probability.
In this study, a long-term observation of gaseous iodine oxoacids has been carried out in two...