Chemistry of Volatile Organic Compounds in the Atmosphere

Joost de Gouw,
ANYL Faculty, CU Boulder

Volatile organic compounds (VOCs) are released from many different natural and man-made sources to the atmosphere. VOCs are removed by different oxidants on time scales of minutes to months and oxidized VOCs, ozone and fine particles are formed as a result. These processes affect air quality and climate and are a challenge to understand due to the large number of different VOCs in the atmosphere and the analytical difficulties in measuring all of these compounds as well as their oxidation products. In our laboratory, we make measurements of VOCs by proton-transfer-reaction time-of-flight mass spectrometry (PTR-TOF) and gas chromatography mass spectrometry (GC-MS). PTR-TOF allows measurements of many different VOCs with high time resolution and without the need for pre-separation or sample treatment. GC-MS allows higher chemical detail, but at the cost of time resolution. We also combine these methods to better understand the compounds that are detected by PTR-TOF in different environments. Several different ongoing and future projects will be presented in this talk. First, we use PTR-TOF for measurements of VOCs from wildfires, in particular those at the wildland urban interface. One particular example is the Marshall Fire in Colorado, and we study the post-fire impacts both on indoor and outdoor air. Second, we are working on the emissions and chemistry of VOCs in urban air. One study that will be highlighted were our field measurements in Denver in the Summer of 2024. Third, we are working on the indoor air chemistry induced by air cleaners such as germicidal UV lamps that are effective at inactivating airborne viruses. Finally, we are also using data from satellite remote sensing instruments to measure the pollutants from oil and natural gas production, in urban air and from wildfires.