Tian Shi-Li, Liu Xue-Jun, Pan Yue-Peng, Zhou Yan-Bo, Xu Wen, Wang Yue-Si
State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China.
College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China.
Huan Jing Ke Xue. 2017 Sep 8;38(9):3605-3609. doi: 10.13227/j.hjkx.201701177.
Reactive nitrogen and sulfur compounds are chemically active in the atmosphere and play an important role in secondary particle formation. Among them, sulfate, nitrate, and ammonium (SNA) are important components of particulate matter (PM) that account for approximately one-third of fine particles. The precursors of SNA including HNO, SO, and NH are all involved in haze formation in China. To date, the concurrent measurements of SNA and their precursors have been limited to single sites and short terms because of the high cost of the instruments. This study aimed to use DELTA (Denuder for Long-Term Atmospheric sampling) to characterize the daily concentrations of reactive nitrogen and sulfur species during haze episodes. The results showed that the background interface of NH, NO, and SO in the denuder was minor and could be used to determine 24-48 h concentrations of NH, HNO, SO, NH, and NO. However, the SO concentrations in the blank filter was so high that they could only be used for sampling weekly or for longer periods of time. During the campaign between May 9 and June 7, 2016 in urban Beijing, the concentrations of NH, HNO, NH, and NO showed distinct daily variations at different wind directions, i.e., higher values were observed during southerly winds and lower values during northerly winds. The time series of these reactive nitrogen compounds coincided with that of PM, CO, SO, and NO, indicating the combustion of fossil fuels. The mean concentrations of NH, HNO, NH, and NO were twice the concentrations during clean days, further highlighting the effect of local emissions on the urban environment. The ratios of HNO/NO and NH/NH were 1.2 and 4.5, respectively, without significant differences between hazy and clean days. The findings demonstrated that both the reduced and oxidized nitrogen were preferred in gaseous phase rather than particulate phase due to relatively high temperatures during the transition season of spring/summer.
活性氮和硫化合物在大气中具有化学活性，在二次颗粒物形成中发挥重要作用。其中，硫酸盐、硝酸盐和铵（SNA）是颗粒物（PM）的重要组成部分，约占细颗粒物的三分之一。SNA的前体包括HNO、SO和NH，均在中国的雾霾形成中起作用。迄今为止，由于仪器成本高昂，SNA及其前体的同步测量仅限于单个站点且时间较短。本研究旨在使用DELTA（长期大气采样剥蚀器）来表征雾霾事件期间活性氮和硫物种的日浓度。结果表明，剥蚀器中NH、NO和SO的背景界面较小，可用于测定NH、HNO、SO、NH和NO的24 - 48小时浓度。然而，空白滤膜中的SO浓度过高，只能用于每周或更长时间的采样。在2016年5月9日至6月7日北京城区的监测期间，NH、HNO、NH和NO的浓度在不同风向呈现出明显的日变化，即南风期间观测值较高，北风期间较低。这些活性氮化合物的时间序列与PM、CO、SO和NO的时间序列一致，表明了化石燃料的燃烧。NH、HNO、NH和NO的平均浓度是清洁日浓度的两倍，进一步突出了本地排放对城市环境的影响。HNO/NO和NH/NH的比值分别为1.2和4.5，雾霾天和清洁天之间无显著差异。研究结果表明，由于春/夏过渡季节温度相对较高，还原态和氧化态氮在气相中比在颗粒相中更占优势。
