南昌市PM_(2.5)中的低分子羧酸:来源鉴定及其对气溶胶酸度的影响

Low-Molecular-Weight Carboxylic Acids in Nanchang:Source Identification and Effects on the Acidity of Aerosols

低分子羧酸是大气气溶胶中的重要水溶性有机化合物,对环境和人类健康具有重要影响。尽管一些研究者对气溶胶中的低分子羧酸进行了研究,但这些研究很少讨论低分子羧酸不同来源的相对重要性,并且关于它们对气溶胶酸度影响程度的研究也很少。为了更好地了解低分子羧酸在气溶胶中的来源和对酸度的影响,于2018年12月1日至2019年8月31日在南昌市收集了210个PM_(2.5)样品,对其进行了水溶性离子和低分子羧酸组成的分析。结果显示,南昌市低分子羧酸主要来自于生物质燃烧,其对羧酸的贡献为34.6%。气态污染物的排放是促进低分子羧酸的形成的主要因素,而较高的湿度和充足的降雨可能会降低低分子羧酸的浓度。通过计算,甲酸,乙酸和草酸对PM_(2.5)酸度的平均贡献分别为0.02%、0.01%、0.04%。这项研究量化了不同来源对气溶胶低分子羧酸贡献的相对重要性,并评估了低分子羧酸对PM_(2.5)酸度的影响程度,为进一步了解气溶胶中有机酸的行为提供帮助。

Low-molecular-weight carboxylic acids(LMWCAs)are an important group of water-soluble organic compounds in atmospheric aerosols that have significant implications on the environment and human health.Although the LMWCAs in atmospheric aerosols have been investigated by many researchers across the world,these studies seldom discuss the relative importance of different sources of LMWCAs,and there are few studies on the degree of their influence on aerosol acidity.In order to better understand the source of LMWCAs in aerosols and their impact on acidity,we collected 210 PM_(2.5)samples in Nanchang from December 1,2018 to August 31,2019.The composition of water-soluble ions and LMWCAs was analyzed.Our results show that LMWCAs in Nanchang mainly come from biomass combustion,and their contribution to carboxylic acid is 34.6%.The emission of gaseous pollutants is the main factor that promotes the formation of LMWCAs,and higher humidity and sufficient rainfall may reduce the concentration of LMWCAs.By calculation,the average contribution of formic acid,acetic acid and oxalic acid to PM_(2.5)acidity is 0.02%,0.01%,and 0.04%,respectively.This study quantified the relative importance of the contribution of different sources to low-molecular-weight carboxylic acids in aerosols,and assessed the impact of LMWCAs on the acidity of PM_(2.5),providing help for further understanding of the behavior of organic acids in aerosols.