Impacts of industrial and biogenic emissions on air quality
Volatile organic compounds play important roles in atmospheric chemistry, air quality and wellness of human being. This dissertation investigated two air quality problems related to volatile organic compounds and compared two techniques used to measure formaldehyde at ambient levels. The first study addresses formaldehyde sources in a local valley, the Lewiston and Clarkston Valley. Two summer field campaigns in 2016 and 2017 measured formaldehyde and a number of other speciated VOCs at three sites. Average formaldehyde mixing ratios were 2.35 ± 0.95 ppbv in 2016 and 4.20 ± 1.2 ppbv in 2017. Formaldehyde displayed strong correlation with SO2 observed both in morning peak events at around 6:30 am PST, accompanied by peaks in reduced sulfur compounds and in the afternoon with short spikes in SO2 and formaldehyde. Formaldehyde abundance was low in the afternoon when abundances of typical secondary pollutants such as NOz and O3 were high. The influence of traffic emissions, biogenic emissions and secondary photoproduction was not pronounced on the local airshed. Primary emissions from the pulp mill were concluded to be the dominant formaldehyde sources in the valley. The second study characterized monoterpene speciation and emission rates in the air from the marijuana growing and processing facilities in Spokane. Whole air samples collected using SUMMA canisters were analyzed with GC-MS. -myrcene, d-limonene, -pinene and -pinene constitute the main monoterpene species with average relative abundance of 40%, 30%, 12% and 4%. High terpinolene abundance was found in some air samples. Estimated emission rates for one of the facilities sampled were 25g hr-1, equivalent to emissions from about 400 ponderosa pine trees. In addition, two different methods used to measure formaldehyde and acetaldehyde in the Lewiston study were compared. The precision of the method dinitrophenylhydrazine cartridge sampling followed by high performance liquid chromatography is reported to be 20 to 30% for formaldehyde and 10% for acetaldehyde in this study. Agreement between proton-transfer-reaction mass spectrometry and the cartridge sampling method is typically larger than 80%, suggesting viable measurements of formaldehyde can be made with this newer technology.