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.

摘要

为了增进我们对大气中甲胺的来源和生产过程及其对颗粒物WSON的贡献的了解，在日本山梨县的一个森林地点同时进行了大小分离的气溶胶和气相中甲胺的同时测量，超过一年。气相，粗模式和细模式颗粒中的甲胺总和的大气甲胺浓度为0.962 ng-N m ^-3一般。在精细模式颗粒中检测到约77％的大气甲胺，在气相中检测到约17％。在精细模式和气态甲胺中发现了类似的季节性变化，包括夏季记录的较高浓度。气态甲胺和氨的浓度之间存在显着的正相关关系，这表明气相中甲胺与氨的来源相似。例如，土壤的挥发和/或森林生物活动的排放。精细模式甲胺的浓度与气态甲胺的浓度呈显着正相关，₄ ^2-（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甲胺。在精细模式甲胺的浓度比与精细模式和气态甲胺的总和与过量的硫酸以完全中和氨的比较中，没有获得显着的正相关。酸比氨更优先与气态甲胺反应。