Leigh R Crilley, Jenna C Ditto, Melodie Lao, Zilin Zhou, Jonathan P D Abbatt, Arthur W H Chan, Trevor C VandenBoer
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引用次数: 0
Abstract
Gas-phase reactive nitrogen species (Nr) are important drivers of indoor air quality. Cooking and cleaning are significant direct sources indoors, whose emissions will vary depending on activity and materials used. Commercial kitchens experience regular high volumes of both cooking and cleaning, making them ideal study locations for exploring emission factors from these sources. Here, we present a total Nr (tNr) budget and contributions of key species NO, NO2, acidic Nr (primarily HONO) and basic Nr (primarily NH3) using novel instrumentation in a commercial kitchen over a two-week period. In general, highest tNr was observed in the morning and driven compositionally by NO, indicative of cooking events in the kitchen. The observed HONO and basic Nr levels were unexpectedly stable throughout the day, despite the dynamic and high air change rate in the kitchen. After summing the measured NOx, HONO and Nr,base fractions, there was on average 5 ppbv of Nr unaccounted for, expected to be dominated by neutral Nr species. Using co-located measurements from a proton transfer reaction mass spectrometer (PTR-MS), we propose the identities for these major Nr species from cooking and cleaning that contributed to Nr,base and the neutral fraction of tNr. When focused specifically on cooking events in the kitchen, a vast array of N-containing species was observed by the PTR-MS. Reproducibly, oxygenated N-containing class ions (C1-12H3-24O1-4N1-3), consistent with the known formulae of amides, were observed during meat cooking and may be good cooking tracers. During cleaning, an unexpectedly high level of chloramines was observed, with monochloramine dominating the profile, as emitted directly from HOCl based cleaners or through surface reactions with reduced-N species. For many species within the tNr budget, including HONO, acetonitrile and basic Nr species, we observed stable levels day and night despite the high air change rate during the day (>27 h-1). The stable levels for these species point to large surface reservoirs which act as a significant indoor source, that will be transported outdoors with ventilation.
气相活性氮物种(Nr)是影响室内空气质量的重要因素。烹饪和清洁是室内的重要直接来源,其排放量会因活动和使用的材料而异。商业厨房经常会有大量的烹饪和清洁活动,因此是探索这些来源的排放因子的理想研究场所。在此,我们使用新型仪器对商业厨房进行了为期两周的检测,得出了总氮氧化物(tNr)预算以及主要物种一氧化氮(NO)、二氧化氮(NO2)、酸性氮氧化物(主要是 HONO)和碱性氮氧化物(主要是 NH3)的贡献。一般来说,在上午观测到的 tNr 最高,由氮氧化物(NO)驱动,表明厨房里有烹饪活动。尽管厨房内的空气变化率很高,但全天观测到的 HONO 和基本 Nr 水平却出乎意料地稳定。将测量到的 NOx、HONO 和 Nr、碱组分相加后,平均有 5 ppbv 的 Nr 未被计算在内,预计主要是中性 Nr 物种。利用质子转移反应质谱仪(PTR-MS)的同位测量,我们提出了烹饪和清洁过程中产生的这些主要 Nr 物种的特性,这些 Nr 物种对 Nr 碱和 tNr 的中性部分有贡献。当特别关注厨房中的烹饪活动时,PTR-MS 观察到了大量含氮物质。在肉类烹饪过程中,可重复观察到含氧 N 类离子(C1-12H3-24O1-4N1-3),与已知的酰胺分子式一致,可能是很好的烹饪示踪剂。在清洁过程中,观察到氯胺的含量出乎意料地高,其中一氯胺占主导地位,它直接从基于 HOCl 的清洁剂中释放出来,或通过与还原 N 物种的表面反应释放出来。对于 tNr 预算中的许多物种,包括 HONO、乙腈和碱性 Nr 物种,尽管白天的换气率很高(>27 h-1),但我们还是观测到了日夜稳定的水平。这些物种的稳定水平表明,有大量的地表储层是重要的室内源,它们会随着通风被带到室外。
期刊介绍:
Environmental Science: Processes & Impacts publishes high quality papers in all areas of the environmental chemical sciences, including chemistry of the air, water, soil and sediment. We welcome studies on the environmental fate and effects of anthropogenic and naturally occurring contaminants, both chemical and microbiological, as well as related natural element cycling processes.