DOI: 10.5194/tc-15-2001-2021
论文题名: Interfacial supercooling and the precipitation of hydrohalite in frozen NaCl solutions as seen by X-ray absorption spectroscopy
作者: Bartels-Rausch T. ; Kong X. ; Orlando F. ; Artiglia L. ; Waldner A. ; Huthwelker T. ; Ammann M.
刊名: Cryosphere
ISSN: 19940416
出版年: 2021
卷: 15, 期: 4 起始页码: 2001
结束页码: 2020
语种: 英语
英文关键词: atmospheric chemistry
; atomic absorption spectroscopy
; chemical reaction
; detection method
; marine environment
; precipitable water
; precipitation (chemistry)
; snow cover
; sodium chloride
; supercooling
; Arctic Ocean
英文摘要: Laboratory experiments are presented on the phase change at the surface of sodium chloride-water mixtures at temperatures between 259 and 241 K. Chloride is a ubiquitous component of polar coastal surface snow. The chloride embedded in snow is involved in reactions that modify the chemical composition of snow as well as ultimately impact the budget of trace gases and the oxidative capacity of the overlying atmosphere. Multiphase reactions at the snow-air interface have been of particular interest in atmospheric science. Undoubtedly, chemical reactions proceed faster in liquids than in solids; but it is currently unclear when such phase changes occur at the interface of snow with air. In the experiments reported here, a high selectivity to the upper few nanometres of the frozen solution-air interface is achieved by using electron yield near-edge X-ray absorption fine-structure (NEXAFS) spectroscopy. We find that sodium chloride at the interface of frozen solutions, which mimic sea-salt deposits in snow, remains as supercooled liquid down to 241 K. At this temperature, hydrohalite exclusively precipitates and anhydrous sodium chloride is not detected. In this work, we present the first NEXAFS spectrum of hydrohalite. The hydrohalite is found to be stable while increasing the temperature towards the eutectic temperature of 252 K. Taken together, this study reveals no differences in the phase changes of sodium chloride at the interface as compared to the bulk. That sodium chloride remains liquid at the interface upon cooling down to 241 K, which spans the most common temperature range in Arctic marine environments, has consequences for interfacial chemistry involving chlorine as well as for any other reactant for which the sodium chloride provides a liquid reservoir at the interface of environmental snow. Implications for the role of surface snow in atmospheric chemistry are discussed. © 2021 BMJ Publishing Group. All rights reserved. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/164650
Appears in Collections: 气候变化与战略
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作者单位: Laboratory of Environmental Chemistry, Paul Scherrer Institut, Villigen PSI, Switzerland; Swiss Light Source (SLS), Paul Scherrer Institut, Villigen PSI, Switzerland; Department of Chemistry and Molecular Biology, Atmospheric Science, University of Gothenburg, Gothenburg, Sweden; Omya International AG, Oftringen, Switzerland
Recommended Citation:
Bartels-Rausch T.,Kong X.,Orlando F.,et al. Interfacial supercooling and the precipitation of hydrohalite in frozen NaCl solutions as seen by X-ray absorption spectroscopy[J]. Cryosphere,2021-01-01,15(4)