Simultaneous measurement of methylamine in size-segregated aerosols and the gas phase
Simultaneous measurement of methylamine in size-segregated aerosols and the gas phase
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DOI：
10.1080/16000889.2021.1875585
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发表时间：
2021-01
期刊：
影响因子：
--
通讯作者：
A. Hirai;K. Matsumoto
中科院分区：
文献类型：
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作者：
A. Hirai;K. Matsumoto
摘要为了提高我们对大气中甲胺的来源和生产过程及其对颗粒物WSON的贡献的认识，在日本山梨县的一个森林地区进行了一年多的甲胺在尺寸分离气溶胶和气相中的同时测量。大气中甲胺的浓度是气相、粗模式和细模式颗粒中甲胺的总和，平均为0.962 ng-N m−3。大气中约77%的甲胺是在精细模式颗粒中检测到的，约17%是在气相中。在细模式和气态甲胺中发现了类似的季节变化，包括在夏季记录的较高浓度。气态甲胺浓度与氨浓度呈显著正相关，说明气态甲胺与氨有相似的来源，如土壤挥发和/或森林生物活动排放。精细模式甲胺浓度与气态甲胺浓度呈显著正相关，细模式甲胺与细模式和气态甲胺之和的浓度比（可作为甲胺从气相到颗粒相转化的指标）与细模式非海盐SO 4 2-呈显著正相关（nss-SO 4 2-）浓度，表明气态甲胺通过与硫酸和/或nss-SO 4 2-的酸碱反应转化为颗粒状甲胺。在细模式甲胺与细模式和气态甲胺的总和的浓度比与过量的硫酸完全中和氨的情况下的比较中未获得显著的正相关性，这意味着硫酸比氨更优先与气态甲胺反应的可能性。
Abstract In order to improve our understanding of the origin and production processes of methylamine in the atmosphere and its contribution to the particulate WSON, simultaneous measurements of methylamine in size-segregated aerosols and the gas phase were conducted at a forested site in Yamanashi Prefecture, Japan, over one year. The concentration of the atmospheric methylamine that is the sum of methylamine in the gas phase, coarse-mode, and fine-mode particles was 0.962 ng-N m−3 on average. About 77% of the atmospheric methylamine was detected in the fine-mode particles and about 17% was in the gas phase. Similar seasonal variations were found in the fine-mode and gaseous methylamine including higher concentrations recorded in summer. The relationship between the concentrations of the gaseous methylamine and ammonia showed a significant positive correlation, suggesting that methylamine in the gas phase has similar sources with ammonia; for instance, the volatilization from soil and/or emission from forest biological activities. The concentration of the fine-mode methylamine showed a significant positive correlation with that of the gaseous methylamine, and the concentration ratio of the fine-mode methylamine to the sum of the fine-mode and gaseous methylamine that can be an indicator of the conversion of methylamine from the gas phase to the particulate phase showed a significant positive correlation with the fine-mode non-sea salt SO4 2- (nss-SO4 2-) concentration, suggesting that the gaseous methylamine is converted into the particulate methylamine through the acid-base reaction with sulfuric acid and/or nss-SO4 2-. Significant positive correlation was not obtained in the comparison of the concentration ratio of the fine-mode methylamine to the sum of the fine-mode and gaseous methylamine with the excessive amount of sulfuric acid for complete neutralization of ammonia, which implies the possibility that the sulfuric acid more preferentially reacts with the gaseous methylamine than ammonia.