Poppendieck Dustin, Robertson Rileigh, Link Michael F
Engineering Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
Indoor Environ. 2024 Mar;1(1). doi: 10.1016/j.indenv.2023.100002.
Every year in the United States conifers are purchased to serve as Christmas trees in homes where they emit volatile organic compounds (VOCs) to the indoor environment. Although many studies have measured the ecosystem-level emissions of VOCs from conifers outdoors (characterizing monoterpene, isoprene, and aldehyde emissions), little is known about VOC emission rates once a conifer is brought indoors. Using a proton transfer reaction-mass spectrometer we characterized the VOCs emitted from a freshly cut Douglas Fir for 17 days in an environmentally controlled chamber. Ozone injections were also performed to analyze indoor chemistry that may occur. Introduction of the tree into the chamber increased the response of 52 mass spectra signals detected by the PTR-MS by at least 500 counts per second (cps) compared to background levels, with concentrations sharply decreasing after the first two days. Monoterpenes were emitted from the tree at a rate of 12.4 mg h the first day and fell to 1 mg h by day three. Overall, monoterpene emissions from this Douglas fir were initially comparable to other strong indoor monoterpene sources (fragranced products and air fresheners) but decayed quickly and, within days, were smaller than other common indoor sources. Addition of ozone to the chamber resulted in decreased monoterpene concentrations that coincided with modest increases in formaldehyde. Four other emitted VOCs were tentatively identified due to their large increase within the first few hours of the tree placed in the chamber, behavior during ozonation, or pattern of accumulation over time.
在美国，每年都有针叶树被买来作为圣诞树放置在家庭中，它们会向室内环境释放挥发性有机化合物（VOCs）。尽管许多研究测量了针叶树在户外生态系统层面的VOCs排放（表征单萜、异戊二烯和醛类排放），但对于针叶树被带入室内后的VOC排放速率却知之甚少。我们使用质子转移反应质谱仪，在一个环境可控的实验舱中对一棵新砍伐的花旗松17天内释放的VOCs进行了表征。还进行了臭氧注入实验以分析可能发生的室内化学反应。将树放入实验舱后，与背景水平相比，质子转移反应质谱仪检测到的52个质谱信号的响应至少增加了每秒500计数（cps），且在前两天后浓度急剧下降。第一天，单萜从树上的释放速率为12.4毫克/小时，到第三天降至1毫克/小时。总体而言，这棵花旗松的单萜排放最初与其他强大的室内单萜来源（香料产品和空气清新剂）相当，但迅速衰减，几天内就低于其他常见室内来源。向实验舱中添加臭氧导致单萜浓度降低，同时甲醛略有增加。由于在树放入实验舱的最初几个小时内大幅增加、臭氧处理期间的行为或随时间的积累模式，还初步鉴定出了其他四种释放的VOCs。
