Down the Tube: A Two-Part Story of Characterizing Marine VOCs

Written By: Delaney Kilgour (Upper Section) & Margaux R.E. Winter (Lower Section)

When you roll down your car windows after a long drive to the beach, what are your first reactions? Do you listen to the waves crash, feel the humid air, or take in the smells? Can you taste the salt in the air? Do you ever know you’re at the beach because, for some reason, it just smells like the beach? Well, it turns out, that characteristic “beach smell” is created by a complex mixture of volatile organic compounds (VOCs) emitted by microorganisms living in the ocean. What is commonly referred to as the smell of the beach comes from sulfur-containing compounds, specifically.

VOCs are emitted by phytoplankton and bacteria that live in the ocean in response to various environmental and biological activities. The most well-studied marine biogenic VOCs include dimethyl sulfide (DMS), isoprene, and monoterpenes. Once emitted, evaporation processes at the air-sea interface can cause these gases to be emitted into the atmosphere, where the gases can then be further aged by oxidation processes to form secondary marine aerosols. These aerosols affect cloud formation, and thus have the capacity to greatly affect our climate.

From Left to Right: Margaux Winter and Delaney Kilgour in front of the Vocus PTR-MS in the Hydraulics Lab
(courtesy of @bertramlab Instagram page)

During SeaSCAPE, Margaux and I study these VOCs emitted at the air-sea interface. We are using a chemical ionization time-of-flight mass spectrometer to measure the gases that are emitted over the course of an induced phytoplankton bloom. One of our primary goals is to characterize a variety of gas emissions, in addition to well-studied gases like DMS, to understand how the gas emission profile varies in response to biological processes in the ocean and how the emission of different gasses relates to the suite of aerosol particles produced.

We work closely with two other teams of researchers (namely Jon Sauer and Alexia Moore from the Prather group at UC San Diego and Emily Barnes from the Goldstein group at UC Berkeley) that also measure VOCs. As a group, we sample from the headspace of the wave flume, in addition to two separate chambers that circulate wave flume water through large, cylindrical glass tubes. Because we all use different instruments with improved sensitivities for certain classes of molecules, our hope is that we can combine our collective data from the various instruments and sampling locations to form a more complete profile of gas emissions during the bloom.

As SeaSCAPE comes to a close, I feel very lucky to have been able to participate in such a large-scale, collaborative experiment during my first year of graduate school. While I was nervous about the intensity of this experiment and working away from my lab in Madison, I quickly realized that everyone here was invested in helping each other and making sure the experiment as a whole was the best possible. I look forward to continuing to work together in the future and for all of our exciting findings.

Similar to many of the undergraduate interns at CAICE, SeaSCAPE has been my first experience on a field campaign. Having studied VOCs and aerosols in two labs prior, I thought I had some baseline as what to expect out of my experiences in the Hydraulics Lab at Scripps Institute of Oceanography (SIO). Of course, past lab and course work familiarized me with the material, but working through CAICE at SIO has been an experience all its own.

In contrast with the sterile, fluorescent environment of my organic chemistry laboratory courses, or the secluded basement that serves as our experimentation space where I work in the Keutsch group, the Hydraulics Lab is of a vastly different nature. The first time walking into the space was overwhelming. The tall, sloping ceiling is reminiscent of a cathedral, or an overturned ark. Despite the few windows, sunlight streams in through the loading dock doors, which are kept open during the day, when the phytoplankton are allowed to fully photosynthesize. Simply arriving in the building, the presence of SeaSCAPE, and the immediacy of the work cannot be overlooked.

Of course, this feeling isn’t generated exclusively from the physical space. Defining my experience at CAICE was the omnipresent and continual collaboration among researchers across different groups. The work demands it.

Photo by Riaan Myburgh on Unsplash

Not only must the three different gas-phase instrumentation teams work together to compare measurements, but if we are interested in seeing how these gasses inform aerosol production we must be in constant communication with everyone working on particle sizing and counting. No matter how much work any one person puts into the quality of their data collection, of equal or perhaps even more importance is the ability of this data to be shared and productively utilized in collaboration with data collected by other groups. Information must be efficiently shared and cross-analyzed each day – sometimes a significant challenge if your own data collection isn’t running smoothly.

So yes, the work demands collaboration, and at CAICE, that collaboration is given freely. Never before I have I been in an environment when so many people are required to work together, and where scientists of different backgrounds and with various skill sets are so willing to give their time and intellectual capacity to all those around them. There is a visceral sense that the work at CAICE is greater than the sum of its parts. Every person in the Hydraulics Lab is committed to the success of the project, and to that end, every person is committed to making the most out of their work, by also making the most out of the work of others.

As the summer comes to a close, I am able to reflect on my experience at CAICE. Of course, the engaged training and education in the field of atmospheric chemistry that I have received is irreplaceable. Learning how to use a Vocus PTR-MS and getting hands-on experience every single day in lab solidified my interest in the field of atmospheric chemistry, augmented what I learn in my school-year course work, and accentuated my ongoing commitment to research.

In the coming weeks, I am incredibly excited to synthesize the research Delaney and I have conducted this summer into a final presentation, and to share the work done here with non-CAICE affiliates when I return to Cambridge in the fall. However, one of the notable takeaways of my experience is the capacity for science to function collaboratively and around the clock. Attempts to answer large-scale, interdisciplinary questions, such as the ones presented at CAICE require the kind of work ethic and ingenuity that I have been fortunate enough to be surrounded by this summer. Bringing a group of dedicated workers together provides the groundwork for action, and I hope to bring this sentiment into my work in the upcoming school year and as I continue my efforts in chemistry in the Keutsch group and in my future graduate studies.

Written by: Delaney Kilgour, Graduate Student in the Bertram Research Group at the University of Wisconsin-Madison and Margaux R.E. Winter, Undergraduate Student in the Keutsch Group at Harvard University

Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation (NSF).

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