State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510 640, China.
Environ Sci Process Impacts. 2019 Aug 14;21(8):1393-1402. doi: 10.1039/c9em00194h.
The hydroxyl radical (OH) is one of the most important oxidants controlling the oxidation capacity of the indoor atmosphere. One of the main OH sources indoors is the photolysis of nitrous acid (HONO). In this study, real-time measurements of HONO, nitrogen oxides (NOx) and ozone (O3) in an indoor environment in Guangzhou, China, were performed under two different conditions: (1) in the absence of any human activity and (2) in the presence of cooking. The maximum NOx and HONO levels drastically increased from 15 and 4 ppb in the absence of human activity to 135 and 40 ppb during the cooking event, respectively. The photon flux was determined for the sunlit room, which has a closed south-east oriented window. The photon flux was used to estimate the photolysis rate constants of NO2, J(NO2), and HONO, J(HONO), which span the range between 8 × 10-5 and 1.5 × 10-5 s-1 in the morning from 9:30 to 11:45, and 8.5 × 10-4 and 1.5 × 10-4 s-1 at noon, respectively. The OH concentrations calculated by photostationary state (PSS) approach, observed around noon, are very similar, i.e., 2.4 × 106 and 3.1 × 106 cm-3 in the absence of human activity and during cooking, respectively. These results suggest that under "high NOx" conditions (NOx higher than a few ppb) and with direct sunlight in the room, the NOx and HONO chemistry would be similar, independent of the geographic location of the indoor environment, which facilitates future modeling studies focused on indoor gas phase oxidation capacity.
羟基自由基 (OH) 是控制室内大气氧化能力的最重要氧化剂之一。室内 OH 的主要来源之一是亚硝酸 (HONO) 的光解。在这项研究中，在中国广州的一个室内环境中，在两种不同条件下实时测量了 HONO、氮氧化物 (NOx) 和臭氧 (O3)：(1) 没有人活动的情况下和 (2) 烹饪时。在烹饪过程中，NOx 和 HONO 的最大浓度分别从无人活动时的 15 和 4 ppb 急剧增加到 135 和 40 ppb。确定了阳光充足的房间的光量子通量，该房间有一个朝东南方向的封闭窗户。光量子通量用于估计 NO2 的光解速率常数 J(NO2) 和 HONO 的光解速率常数 J(HONO)，它们在上午 9:30 到 11:45 之间的范围分别为 8×10-5 和 1.5×10-5 s-1，中午分别为 8.5×10-4 和 1.5×10-4 s-1。通过光稳定态 (PSS) 方法计算的 OH 浓度，中午左右观察到的浓度非常相似，即在无人活动和烹饪时分别为 2.4×106 和 3.1×106 cm-3。这些结果表明，在“高 NOx”条件下（NOx 高于几个 ppb）并且室内有直射阳光的情况下，NOx 和 HONO 化学性质相似，与室内环境的地理位置无关，这有助于未来针对室内气相氧化能力的建模研究。
