Atmospheric Chemistry Program Seminar
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 with oxidized VOCs, ozone and fine particles as a result. These processes affect air quality and climate and are a challenge to understand due to the large number of different VOCs that are released to 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 seminar. First, we use PTR-TOF for measurements of VOCs in indoor environments to better understand their sources and fate. One particular study involves the impact of the Marshall Fire in Boulder County on indoor air in homes that were near the burnt area. Second, we are working on the emissions and chemistry of VOCs in urban air. One study that will be highlighted involved field measurements in Los Angeles in the Summer of 2022. Third, we are working on a chamber study to better understand the formation of secondary organic aerosol from biogenic VOCs. Finally, we are also using data from satellite remote sensing instruments to measure the pollutants from oil and natural gas production, and from wildfires."
Understanding aerosols for pollution, climate change, and disease transmission
ANYL faculty, CU Boulder
"Our group’s research focuses on understanding the sources, properties, transformations, and sinks of aerosols (and of the gases that interact with them), which have major effects on human health and climate. In this talk I will briefly present results from different projects over the last year, as well as some future directions for our group. (1) I will introduce our aircraft research program, including results from recent projects, and how they set up scientific questions for the upcoming NASA ASIA-AQ project on multiple megacities (if politics allows: Tokyo, Seoul, Manila, Bangkok, Kolkata, Dhaka, Hanoi, Singapore, and Kuala-Lumpur). (2) I will present preliminary results from the CalNexT-2022 field study in the Los Angeles area, where we returned (along with Prof. de Gouw’s group and other colleagues) to the Caltech campus 12 years after CalNex-2010. Analysis so far suggests that ½ of the SOA potential in ambient air is due to species less volatile than sesquiterpenes and aromatics (c* < 1e4 ug m-3). (3) I will discuss recent results on COVID airborne transmission, as well as the indoor chemistry due to germicidal ultraviolet (GUV) air disinfection and other commercial “air cleaners”.
For those interested in COVID-19 aerosol transmission, you can find a summary of the evidence supporting airborne transmission of COVID-19 at https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(21)00869-2/, a review for airborne transmission of all respiratory diseases at https://doi.org/10.1126/science.abd9149, an overview of how airborne transmission really works at https://doi.org/10.1111/ina.13025, and an overview of the historical reasons for the confusion on this topic at https://doi.org/10.1111/ina.13070."