大气中氨基酸的来源及氮同位素分馏机制

doi:10.13745/j.esf.sf.2025.3.25

摘要/Abstract

摘要：

近年来气溶胶中包括游离态氨基酸(FAAs)和结合态氨基酸(CAAs)在内的蛋白质类物质已被广泛关注。这是因为氨基酸在全球气候变化、空气污染物的去除效率、大气氮的生物利用性、二次有机气溶胶的形成以及对人体健康的影响等方面发挥着重要作用。本文将重点阐述氨基酸单体的稳定氮同位素这一新技术在示踪大气氨基酸来源和转化过程中的应用,综述潜在大气释放源中氨基酸单体的稳定氮同位素特征及其在燃烧和大气过程中的稳定氮同位素分馏机制。在未来的工作中需进一步研究不同粒径大小、不同气象条件下和特殊污染事件中的氨基酸单体的同位素分馏机制,这将有助于阐明氨基酸在云和降水形成、气候变化以及污染事件中所发挥的作用和贡献。

关键词: 游离态氨基酸, 结合态氨基酸, 稳定氮同位素, 分馏机制

Abstract:

In recent years, amino acids in aerosols, including free amino acids (FAAs) and combined amino acids (CAAs), have attracted widespread attention. This is due to the significant roles these proteinaceous substances play in global climate change, the removal efficiency of air pollutants, the bioavailability of atmospheric nitrogen, the formation of secondary organic aerosols, and their effects on human health. This paper focuses on the application of stable nitrogen isotopes of compound-specific amino acids, a new technique, in tracing the sources and transformation processes of atmospheric amino acids. It reviews the stable nitrogen isotope characteristics of individual amino acids in potential atmospheric protein emission sources, as well as the mechanisms of stable nitrogen isotope fractionation during combustion processes and atmospheric transformations. Future research should further investigate the isotopic fractionation mechanisms of individual amino acid under different particle sizes, meteorological conditions, and special pollution events. This will help clarify the role and contribution of amino acids in cloud and precipitation formation, climate change, and pollution events.

Key words: free amino acids, combined amino acids, stable nitrogen isotopes, fractionation mechanisms

中图分类号:

P402

朱仁果, 肖化云. 大气中氨基酸的来源及氮同位素分馏机制[J]. 地学前缘, 2025, 32(3): 362-374.

ZHU Renguo, XIAO Huayun. Sources and nitrogen isotope fractionation mechanisms of atmospheric amino acids[J]. Earth Science Frontiers, 2025, 32(3): 362-374.

图/表 5

图1 主要释放源中游离甘氨酸的氮同位素值(据文献[25]) NA表示未检出。

Fig.1 The average of δ15N for free Gly from major emission sources. Adapted from [25]. NA represents not detected.

表1 主要游离态和结合态甘氨酸释放源的氮同位素值(据文献[27]的补充材料修改)

Table 1 Nitrogen isotope values of major sources of free and combined glycine release (modified after [27])

源	样本数量	δ¹⁵N值/‰
源	样本数量	平均值	分析精度	最小值	最大值
植物源中游离Gly	21	-13.4	3.0	-19.3	-7.6
土壤源中游离Gly	5	5.2	3.5	1.2	9.4
生物质燃烧源游离Gly	6	22.4	4.4	16.9	27.3
植物源中结合Gly	5	-11.1	2.7	-13.2	-6.6
土壤源中结合Gly	7	2.6	4.6	-1.6	7.8
生物质燃烧源结合Gly	6	19.2	0.6	18.1	19.8

图2 生物质燃烧、土壤、植物源和PM2.5中游离态和结合态氨基酸单体的百分占比分布(据文献[27]修改) 图中氨基酸缩写的全称为:丙氨酸(Ala),甘氨酸(Gly),缬氨酸(Val),亮氨酸(Leu),异亮氨酸(Ile),γ-氨基丁酸(Gaba),脯氨酸(Pro),蛋氨酸(Met),丝氨酸(Ser),苏氨酸(Thr),苯丙氨酸(Phe),天冬氨酸(Asp),谷氨酸(Glu),天冬酰胺(Asn),赖氨酸(Lys),谷氨酰胺(Gln),精氨酸(Arg),组氨酸(His),酪氨酸(Tyr),色氨酸(Trp),鸟氨酸(Orn),半胱氨酸(Cys)和高丝氨酸(Homoser)。

Fig.2 Distribution of free amino acid and combined amino acids in biomass burning, soil, plant sources, and PM2.5. Modified after [27].

图3 蛋白质物质在大气中可能经历的光化学和微生物过程(据文献[25,27]修改)

Fig.3 Photochemical and microbial processes that proteins may undergo in the atmosphere. Modified after [25,27].

图4 蛋白质类物质在燃烧过程中可能发生的化学反应(据文献[25,91]修改)

Fig.4 Chemical reactions that proteinaceous compounds may undergo during combustion. Modified after [25,91].

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