青岛大气气溶胶中游离氨基化合物的浓度、组成和来源

氨基化合物是大气气溶胶中一类重要的有机氮化合物,由于其具有吸湿性,且沉降入海后可被海洋浮游生物直接利用,因此,可能在大气化学方面和海洋生态系统中具有重要作用.基于此,本研究利用2007年6月至2008年5月在青岛采集的55个总悬浮颗粒物样品,采用邻苯二甲醛/N-乙酰-L-半胱氨酸柱前衍生高效液相色谱法,分析了其中游离氨基化合物(FAC)的浓度.结果表明,气溶胶中总FAC浓度为0.14~8.33 nmol·m^-3,其中,精氨酸、甲胺和丙氨酸的贡献最大.不同季节FAC的组成不同,精氨酸在夏、秋季节对FAC的贡献高于冬、春季节,甲胺的相对贡献则在夏季较低,而冬、春季较高.采样期间气团来源和天气状况的不同会影响气溶胶中FAC的浓度和组成.FAC在受南方陆源影响的气溶胶中浓度最高,北方陆源次之,海洋源气溶胶中的浓度最低,蛋白质类氨基化合物对总FAC的贡献在海洋源气溶胶中最高,在南方陆源气溶胶中最低.雾天和烟霾时气溶胶中FAC的浓度分别为晴天时的2.5倍和1.8倍,沙尘天气时FAC浓度与晴天时基本相当,蛋白质类氨基化合物对总FAC的贡献在晴天和雨后相对较高,在烟霾和雾天时相对较低.

Sources, compositions and distributions of free amino compounds in atmospheric aerosols at Qingdao

Amino compound is considered as an important part of organic nitrogen compounds in atmospheric aerosols because of their potential impact on atmospheric chemistry and climate change. These compounds might also have a significant influence on the marine ecosystem via atmospheric deposition. In this study, 55 total suspended particles samples were collected at Qingdao during the period from June, 2007 to May, 2008. Concentrations of free amino compounds (FAC) were measured using an approach in which precolumn fluorescence derivatization with o-phthaldialdehyde and N-isobutyryl-L-cysteine was used, followed by the chemical analysis with a reverse-phase high performance liquid chromatography. FAC concentrations ranged from 0.14 to 8.33 nmol·m^-3 in Qingdao. In these FAC, arginine, methylamine and alanine were the most abundant components. Composition of FAC in aerosols exhibited a distinctive seasonal variation. The contributions of arginine to the total FAC were higher in summer and autumn than in winter and spring. The contribution of methylamine to the total FAC were higher in winter and spring, but lower in summer. When the orgins of air mass were considered, the highest and the lowest cconcentrations of the total FAC were associated with the air mass originating from the south and marine atmosphere, respectively. When the air mass originated from the north, the concentrations of FAC were lower between the highest from the south and the lowest from the marine. In addition, contributions of protein-type to the total FAC were the highest in the aerosols from marine atmosphere while the lowest contribution occurred in the aerosols from the south. When the meorological conditions were considered, the concentrations of FAC during fog and haze episodes were 2.5 times and 1.8 times higher than those during clear weather conditions, respectively. However, contributions of protein-type to the total FAC were higher in the aerosols collected after rain and during clear days, when compared to those during haze and fog episodes. It was found that the FAC concentrations in dust days were comparable to those in clear days.