Cooperative Institute for Research in Environmental Sciences

Atmospheric Chemistry Program Seminar: Dongwook Kim, CU-ANYL Chem

Monday October 24 2022 @ 12:15 pm

October

24

Mon

2022

12:15 pm

Event Type
Seminar
Availability

Open to Public

Audience
  • CIRES employees
  • Science collaborators
  • Host
    CIRES

    Quantifying particulate halogens in the atmosphere: Airborne measurements and instrumentation
    Dongwook Kim,
    ANYL 3rd year, Jimenez group
    "Halogens in the atmosphere play important roles in ozone chemistry. Halogen chemistry studies have been mainly focused on gas-phase chlorine, iodine, and bromine chemistry. Particulate halogens can be a reservoir for reactive halogens and can directly interact with ozone. However, they have not been well-constrained in chemical transport models due to a lack of measurements on a global scale. Recently, we have quantified submicron particulate halogens, as well as speciation of oxidation states, from several airborne datasets measured by the University of Colorado High-Resolution Aerodyne Aerosol Mass Spectrometer (CU-HR-AMS). We have identified sources that were previously not well recognized. We present particulate halogen measurements (i.e., I, Br, ClO4-) over urban, remote, and wildfire conditions as well as instrumental development for stratospheric aerosol sampling.
    (1) On aircraft platforms, AMS uses an aerodynamic lens that requires constant upstream pressure to work consistently. Airborn interfaces that provide that (pressure-controlled inlets –PCI-) have historically performed less well at high altitudes. We show the recent development of a new PCI inlet design coupled with a PM2.5 aerodynamic lens towards the goal of sampling PM1 aerosols up to ~15 km altitude.
    (2) The first quantitative detection of iodine (both particle and gas phase) in the stratosphere has been reported (Koenig et al., 2020). It suggested that particulate iodine is a major fraction in the stratosphere. We present particulate iodine measurement up to the lower stratosphere over the Pacific Ocean during NSF TI3GER and its implications for stratospheric ozone.
    (3) Reactive halogens (i.e., chlorine and bromine) can affect urban air quality by providing radical sources. We show that particulate bromine is emitted by anthropogenic sources and compare it with other ground measurements. Also, we identify particulate iodine sources and discuss the potential impact on air quality.
    (4) We quantify the emission of particulate iodine from Western US wildfires during FIREX-AQ. We found that particulate fore could be the major form of iodine emission from US wildfires.
    (5) Exposure to perchlorate affects the human endocrine system. While the atmospheric sources of perchlorate are highly uncertain, snow and ice core records suggest that chlorofluorocarbons (CFCs) might be important precursors for the photochemical production of perchlorate in the stratosphere. We show the first global in-situ perchlorate measurements from the ATom campaign over the remote oceans and comparison to the GEOS-Chem model with updated perchlorate-related mechanisms. Also, we show anthropogenic emissions of perchlorate that may affect the tropospheric perchlorate burden. "