Browsing by Subject "NITRYL CHLORIDE"

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  • Fan, Xiaolong; Cai, Jing; Yan, Chao; Zhao, Jian; Guo, Yishuo; Li, Chang; Dällenbach, Kaspar; Zheng, Feixue; Lin, Zhuohui; Chu, Biwu; Wang, Yonghong; Dada, Lubna; Zha, Qiaozhi; Du, Wei; Kontkanen, Jenni; Kurten, Theo; Iyer, Siddhart; Kujansuu, Joni T.; Petäjä, Tuukka; Worsnop, Douglas R.; Kerminen, Veli-Matti; Liu, Yongchun; Bianchi, Federico; Tham, Yee Jun; Yao, Lei; Kulmala, Markku (2021)
    Gaseous hydrochloric (HCl) and hydrobromic acid (HBr) are vital halogen species that play essential roles in tropospheric physicochemical processes. Yet, the majority of the current studies on these halogen species were conducted in marine or coastal areas. Detection and source identification of HCl and HBr in inland urban areas remain scarce, thus limiting the full understanding of halogen chemistry and potential atmospheric impacts in the environments with limited influence from the marine sources. Here, both gaseous HCl and HBr were concurrently measured in urban Beijing, China, during winter and early spring of 2019. We observed significant HCl and HBr concentrations ranging from a minimum value at 1 x 10(8) molecules cm(-3) (4 ppt) and 4 x 10(7) molecules cm 3 (1 ppt) up to 6 x 10(9) molecules cm(-3) (222 ppt) and 1 x 10(9) molecules cm(-3) (37 ppt), respectively. The HCl and HBr concentrations are enhanced along with the increase of atmospheric temperature, UVB and levels of gaseous HNO3. Based on the air mass analysis and high correlations of HCl and HBr with the burning indicators (HCN and HCNO), gaseous HCl and HBr are found to be related to anthropogenic burning aerosols. The gas-particle partitioning may also play a dominant role in the elevated daytime HCl and HBr. During the daytime, the reactions of HCl and HBr with OH radicals lead to significant production of atomic Cl and Br, up to 2 x 10(4) molecules cm(-3) s(-1) and 8 x 10(4) molecules cm(-3) s(-1), respectively. The production rate of atomic Br (via HBr + OH) is 2-3 times higher than that of atomic Cl (via HCl + OH), highlighting the potential importance of bromine chemistry in the urban area. On polluted days, the production rates of atomic Cl and Br are faster than those on clean days. Furthermore, our observations of elevated HCl and HBr may suggest an important recycling pathway of halogen species in inland megacities and may provide a plausible explanation for the widespread halogen chemistry, which could affect the atmospheric oxidation in China.
  • Yan, Chao; Tham, Yee Jun; Zha, Qiaozhi; Wang, Xinfeng; Xue, Likun; Dai, Jianing; Wang, Zhe; Wang, Tao (2019)
    Nitrate radical (NO3) and dinitrogen pentoxide (N2O5) play crucial roles in the nocturnal atmosphere. To quantify their impacts, we deployed a thermal-dissociation chemical ionization mass spectrometry (TD-CIMS), to measure their concentration, as well as ClNO2 at a coastal background site in the southern of China during the late autumn of 2012. Moderate levels of NO3, N2O5 and high concentration of ClNO2 were observed during the study period, indicating active NOx-O-3 chemistry in the region. Distinct features of NO3, N2O5 and ClNO2 mixing ratios were observed in different airmasses. Further analysis revealed that the N2O5 heterogeneous reaction was the dominant loss of N2O5 and NO3, which showed higher loss rate compared to that in other coastal sites. Especially, the N2O5 loss rates could reach up to 0.0139 s(-1) when airmasses went across the sea. The fast heterogeneous loss of N2O5 led to rapid NOx loss which could be comparable to the daytime process through NO2 oxidization by OH, and on the other hand, to rapid nitrate aerosol formation. In summary, our results revealed that the N2O5 hydrolysis could play significant roles in regulating the air quality by reducing NOx but forming nitrate aerosols. (C) 2019 Published by Elsevier B.V.
  • Lee, Ben H.; Lopez-Hilfiker, Felipe D.; Veres, Patrick R.; McDuffie, Erin E.; Fibiger, Dorothy L.; Sparks, Tamara L.; Ebben, Carlena J.; Green, Jaime R.; Schroder, Jason C.; Campuzano-Jost, Pedro; Iyer, Siddharth; D'Ambro, Emma L.; Schobesberger, Siegfried; Brown, Steven S.; Wooldridge, Paul J.; Cohen, Ronald C.; Fiddler, Marc N.; Bililign, Solomon; Jimenez, Jose L.; Kurten, Theo; Weinheimer, Andrew J.; Jaegle, Lyatt; Thornton, Joel A. (2018)
    We describe the University of Washington airborne high-resolution time-of-flight chemical ionization mass spectrometer (HRToF-CIMS) and evaluate its performance aboard the NCAR-NSF C-130 aircraft during the recent Wintertime INvestigation of Transport, Emissions and Reactivity (WINTER) experiment in February-March of 2015. New features include (i) a computer-controlled dynamic pinhole that maintains constant mass flow-rate into the instrument independent of altitude changes to minimize variations in instrument response times; (ii) continuous addition of low flow-rate humidified ultrahigh purity nitrogen to minimize the difference in water vapor pressure, hence instrument sensitivity, between ambient and background determinations; (iii) deployment of a calibration source continuously generating isotopically labeled dinitrogen pentoxide ((N2O5)-N-15) for in-flight delivery; and (iv) frequent instrument background determinations to account for memory effects resulting from the interaction between sticky compounds and instrument surface following encounters with concentrated air parcels. The resulting improvements to precision and accuracy, along with the simultaneous acquisition of these species and the full set of their isotopologues, allow for more reliable identification, source attribution, and budget accounting, for example, by speciating the individual constituents of nocturnal reactive nitrogen oxides (NOz=ClNO2+2xN(2)O(5)+HNO3+etc.). We report on an expanded set of species quantified using iodide-adduct ionization such as sulfur dioxide (SO2), hydrogen chloride (HCl), and other inorganic reactive halogen species including hypochlorous acid, nitryl chloride, chlorine, nitryl bromide, bromine, and bromine chloride (HOCl, ClNO2, Cl-2, BrNO2, Br-2, and BrCl, respectively).
  • Tham, Yee Jun; Wang, Zhe; Li, Qinyi; Wang, Weihao; Wang, Xinfeng; Lu, Keding; Ma, Nan; Yan, Chao; Kecorius, Simonas; Wiedensohler, Alfred; Zhang, Yuanhang; Wang, Tao (2018)
    Heterogeneous uptake of dinitrogen pentoxide (N2O5) and production of nitryl chloride (ClNO2) are important nocturnal atmospheric processes that have significant implications for the production of secondary pollutants. However, the understanding of N2O5 uptake processes and ClNO2 production remains limited, especially in China. This study presents a field investigation of the N2O5 heterogeneous uptake coefficient (gamma (N2O5)) and ClNO2 production yield (phi) in a polluted area of northern China during the summer of 2014. The N2O5 uptake coefficient and ClNO2 yield were estimated by using the simultaneously measured ClNO2 and total nitrate in 10 selected cases, which have concurrent increases in the ClNO2 and nitrate concentrations and relatively stable environmental conditions. The determined gamma (N2O5) and phi values varied greatly, with an average of 0.022 for gamma (N2O5) (+/- 0.012, standard deviation) and 0.34 for (15 (+/- 0.28, standard deviation). The variations in gamma (N2O5) could not be fully explained by the previously derived parameterizations of N2O5 uptake that consider nitrate, chloride, and the organic coating. Heterogeneous uptake of N2O5 was found to have a strong positive dependence on the relative humidity and aerosol water content. This result suggests that the heterogeneous uptake of N2O5 in Wangdu is governed mainly by the amount of water in the aerosol, and is strongly water limited, which is different from most of the field observations in the US and Europe. The ClNO2 yield estimated from the parameterization was also overestimated comparing to that derived from the observation. The observation-derived phi showed a decreasing trend with an increasing ratio of acetonitrile to carbon monoxide, an indicator of biomass burning emissions, which suggests a possible suppressive effect on the production yield of ClNO2 in the plumes influenced by biomass burning in this region. The findings of this study illustrate the need to improve our understanding and to parameterize the key factors for gamma (N(2)O5) and phi to accurately assess photochemical and haze pollution.
  • Li, Yuanyuan; Nie, Wei; Liu, Yuliang; Huang, Dandan; Xu, Zheng; Peng, Xiang; George, Christian; Yan, Chao; Tham, Yee Jun; Yu, Chuan; Xia, Men; Fu, Xiao; Wang, Xinfeng; Xue, Likun; Wang, Zhe; Xu, Zhengning; Chi, Xuguang; Wang, Tao; Ding, Aijun (2020)
    Titanium dioxide (TiO2) is extensively used with the process of urbanization and potentially influences atmospheric chemistry, which is yet unclear. In this work, we demonstrated strong production of Cl-2 from illuminated KCl-coated TiO2 membranes and suggested an important daytime source of chlorine radicals. We found that water and oxygen were required for the reactions to proceed, and Cl-2 production increased linearly with the amount of coated KCl, humidity of the carrier gas, and light intensity. These results suggested that water promotes the reactivity of coated KCl via interaction with the crystal lattice to release free chloride ions (Cl-). The free Cl- transfer charges to O-2 via photoactivated TiO2 to form Cl-2 and probably the O-2(-) radical. In addition to Cl-2, ClO and HOCl were also observed via the complex reactions between Cl/Cl-2 and HOx. An intensive campaign was conducted in Shanghai, during which evident daytime peaks of Cl-2 were observed. Estimated Cl-2 production from TiO2 photocatalysis can be up to 0.2 ppb/h when the TiO2-containing surface reaches 20% of the urban surface, and highly correlated to the observed Cl-2. Our results suggest a non-negligible role of TiO2 in atmospheric photochemistry via altering the radical budget.