Hi!
I’m a scientist and I research the atmosphere.
It’s rather important - and very fragile.
Maybe you’ve used it?
I am…
an atmospheric chemist and science communicator
a researcher at the Paul Scherrer Institute (PSI) in Switzerland
a Ph.D. from the Brown group at CU Boulder and Tropospheric Chemistry at NOAA
usually exploring a mountain
in the field taking measurements of atmospheric pollutants
mostly indoors trying to understand those measurements
Science Communication
Perhaps the most pressing scientific challenge
Producing knowledge is not useful if only experts understand its importance. Below are some examples of how I work to communicate science.
Past senior editor and writer
From space missions to minuscule microbes, Science Buffs covers STEM research at the University of Colorado Boulder and beyond.
Zach Decker presenting on the NOAA Twin Otter science mission during the FIREX-AQ Research Campaign at the NOAA Outreach booth during the American Geophysical Union Meeting
As a public presenter
Whether as a guest on a Buffs Talk Science podcast, or as a co-wizard at a CU wizards STEM seminar for kids I am always looking to spread exciting science!
Current Research
Nanoparticles are in the air - especially near airports
Zachary Decker (left) and Peter Alpert (right) discussing at the field research site near the Zürich airport.
Inside the APPROPRIATE measurement trailer stationed nearby the Zürich airport.
Particulate matter (PM) is a pollutant with major implications for our health, welfare, and the global climate. One can often see particulate matter, such as dust or smoke, in the air. However, Ultra Fine Particles (UFPs) are harder to see because they are about 100 times smaller than human hair, or the size of a coil of DNA.
High concentrations of UFPs are consistently detected near airports. This is a problem for human health because UFPs can lodge deep in your lung tissue and permeate the blood-brain barrier. For example, multiple studies find an increased occurance of brain tumors for residents exposed to airport UFPs. In other words, the closer one lives to the airport the higher risk of developing brain cancers. (1,2)
Yet, the source of UFPs near airports is not clear. Airports emit UFPs, but the emissions are complex mixtures of aircraft engine exhaust, vehicle exhaust, and other emissions such as tire rubber. Some emissions begin as particles, but others as gas-phase molecules that grow into particles. We want to untangle these emissions and learn how the emissions transform into UFPs and thus understand their chemical makeup.
To do just this, we deployed an impressive suite of state-of-the-art instrumentation from the Paul Scherrer Institute’s Laboratory for Atmospheric Chemistry. As part of the research campaign called Aviation Plume PROPeRtIes AT point of Exposure (APPROPRIATE 2022-2023), we conducted laboratory investigations of aircraft oils and fuels. We then moved our instrumentation to the field at an engine test cell to sample real engine exhaust directly. Finally, we moved once again to the Zürich airport to sample real-world conditions. We are now meticulously combing through terabytes of data collected during APPROPRIATE to find the chemical fingerprints of ultrafine particles.
1. Wu, A. H. et al. Association between airport-related ultrafine particles and riskof malignant brain cancer: A Multiethnic Cohort Study.Cancer Res.81,4360–4369 (2021).
2. Weichenthal, S. et al. Within-city spatial variations in ambient ultrafineparticle concentrations and incident brain tumors in adults.Epidemiology31,177–183 (2020).
Balancing the Molecular Scale
Gasses are introduced into the atmosphere always and everywhere. On the time scale of weeks to years, the gasses are transformed into smaller and smaller molecules - eventually reaching their minimalist form of carbon monoxide (CO) and carbon dioxide (CO2). Even more, molecules can condense into particles from nanoparticles to sand and dust. A total accounting of our atmosphere would require a total accounting of these gasses and particles - an insurmountable challenge.
Gasses and particles are measured continuously atop the Jungfraujoch (JFJ), a high-altitude research station in Switzerland. Measurements are made jointly between 1) Paul Scherrer Institute (PSI), 2) Swiss Federal Laboratories for Materials Science and Technology, 3) the Global Atmosphere Watch program of the World Meteorological Organization, and 4) Aerosol, Clouds, and Trace Gas Research Infrastructure (ACTRIS).
The location is ideal to sample air from around the world including wildfires from the U.S., Saharan dust storms blown from Africa, or simply local pollution from the valley town below. In an effort to close the “Carbon Budget”, or the total molecular budget of our atmosphere, the “Carbon Balance Campaign” (CBC) was created. We combine ongoing measurements at the JFJ with additional measurements from researchers across Europe.
Nora Nowak, CBC principal investigator, calibrating instrumentation
The famous Jungfrau Peak (left) and the Jungfraujoch station (right)
Wildfires are increasing
View from the window of the NOAA Twin Otter sampling smoke during the FIREX-AQ research campaign.
It is well-known that wildfires can degrade our air quality at local, regional and global scales. Sadly, wildfires are increasing in size across the western U.S., leading to increases in human smoke exposure and their associated negative health impacts. For example, towns impacted by smoke also have increased cases of influenza, and even COVID-19.
This increase is caused by anthropogenic influences such as human-caused climate change and past wildland management practices. Yet, the underlying chemistry within wildfire smoke plumes is not well understood. So, to change this NASA and NOAA joined forces to create the Fire Influence on Regional to Global Environments Experiment - Air Quality (FIREX-AQ). FIREX-AQ was a major field study in 2019 that combined airborne, ground-based, and satellite measurements of wildfire and agricultural burning smoke.
During FIREX-AQ I took chemical measurements aboard the NOAA Chemistry Twin Otter Aircraft. We were the first group to focus on nighttime wildfire smoke chemistry, a severely understudied component of wildfires.
FIREX-AQ produced an immense amount of data that hundreds of scientists are analyzing. Years later, we are still uncovering new findings in the data. I am working through our FIREX-AQ dataset to tease out the details of some of the most important chemical reactions that may degrade our air quality.
Research Outcomes
Wildfire smoke is filled with “Dark Chemistry”
The smoke from fires (biomass burning) contains thousands of different molecules. When the summer smoke haze reaches our town or the winter smell of a fireplace reaches our nose we are breathing in these molecules. To understand how those molecules affect our health we must first know which molecules are actually in smoke! To make things more difficult, a lot of the molecules evolve - they react and change - as the smoke ages. Going further, nighttime smoke and daytime smoke change differently because of sun exposure. During my Ph.D., I investigated which smoke molecules are likely the most important for air quality degradation and found the surprising result that “Dark Chemistry” happens at all times of the day.
Age Matters
Just like your car engine an aircraft engine needs oil, and eventually an oil change. Oil is tough - it avoids degradation - yet small amounts of oil are exhausted as gas and particles. Even when the sky appears clear, we detect particles containing the molecular fingerprints of oil near the Zürich airport. Thanks to extensive laboratory studies of brand-new and used oil we can identify this oil using state-of-the-art instrumentation called mass spectrometers. Our work is currently preliminary, but we are working to understand how the molecular fingerprint may relate to the formation of oil particles in the air. With some hope, this information could be used to make oil that is safer for surrounding communities.