Sources, compositions and distributions of free amino compounds in atmospheric aerosols at Qingdao
青岛大气气溶胶中游离氨基化合物的浓度、组成和来源

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.