Where the ocean meets the air

A National Science Foundation collaborative project between researchers from the University of Delaware and the University of Georgia to better understand how nutrients, pollutants and organic matter are exchanged between the air and the sea recently conducted a research cruise in the North Atlantic Ocean. The cruise aboard UD’s Research Vessel Hugh R. Sharp to study the sea surface microlayer was designed to better understanding the role it plays in regulating carbon cycles and climate.

Andrew Wozniak, associate professor in the School of Marine Science and Policy (SMSP), is the UD project lead while the project lead for UGA is Amanda Frossard, associate professor in the Department of Chemistry at UGA. 

Wozniak said the sea surface microlayer is a unique micro-environment. 

“It accumulates organic material of a certain kind and then it reaches the air-sea interface and accumulates there, and that creates interesting physical properties that influence the exchange of materials back and forth,” said Wozniak. “We thought that if we can do a better job of understanding how the chemistry of the organic matter changes in space and time due to the ocean processes and biology, then we’ll have a better understanding of how these gases exchange and how the particles that are emitted to the atmosphere can influence atmospheric chemistry.” 

Frossard explained that the research team is interested in studying what are known as surfactants, compounds that reduce the surface tension of a liquid such as seawater and accumulate in surface waters and the sea surface microlayer due to their affinity for surfaces and interfaces, such as rising bubbles in the ocean. 

One of the main goals of the project is to look at and better understand these surfactants. 

“We want to understand what surfactants are in the ocean, how they partition to the microlayer and what affects their concentration and their composition,” said Frossard. “We're collecting samples here, some that we're processing on the ship, but we're taking all of them back to the lab to do different analyses. We'll use these results to understand the sea surface microlayer and further understand air-sea gas exchange as well as the emission of particles from the ocean into the atmosphere.” 

Frossard was joined on the cruise by four of her graduate students: Daniel Ammer, Amber Birt, Ellie Smerznak, and Mara Shields. An important research experience that also aligns with the developing new knowledge about these critical Earth cycles. Our thanks to the UD team for sharing the story.

Image: Researchers aboard UD’s Research Vessel Hugh R. Sharp working with a Rosette sampler. Photo by Audrey Tong