Generales

By Carlos Olimpo Restrepo S., Journalist at UdeA Communications Office 

Researchers from the University of A Coruña in Turbo and the University of Oldenburg in Germany conducted the first study of the ocean’s surface microlayer in a tropical estuary—the Gulf of Urabá. Their findings reveal a greater concentration of surfactants in this area compared to other ocean regions, which impacts the climate and poses risks to marine life. 

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Photo: Courtesy / Karen Moreno. 

In the Gulf of Urabá, surfactant levels in the sea surface microlayer (SML) increase markedly during the rainy season. These increased concentrations can reduce the exchange of gases, such as carbon dioxide (CO₂), between the ocean and atmosphere by up to 23%. This reduction could intensify global warming. 

The sea surface microlayer (SML) forms an almost invisible film, only about a millimeter thick, that covers roughly 70% of the Earth’s oceans. This layer contains organic matter, including surfactants—compounds that behave like a soap film. As the film thickens, it restricts the movement of CO₂ between the ocean and the atmosphere. This restriction can cause temperatures in the nearby air to increase. 

A crucial conclusion of the project “Surfactant distribution can impact air-sea exchange in a Tropical Estuarine System in the Caribbean” comes from students and faculty of the Oceanography program at the Universidad de Antioquia in Turbo. Since 2018, they have collaborated with researchers from the University of Oldenburg in Germany, collecting samples and data for analysis in cutting-edge laboratories in Europe. 

The research found that more than 80% of the surfactant levels surpassed the threshold for high surface activity, highlighting a significant impact on the biogeochemical cycles of these tropical ecosystems. As a result, CO₂ has trouble escaping into the atmosphere, and nutrients and microscopic organisms in the sea experience difficulties mixing and moving, which can affect marine life. 

Mariana Ribas Ribas, a chemical oceanographer at the Institute of Chemistry and Biology of Marine Environments, Carl von Ossietzky University of Oldenburg, explained, “Surfactants reduce the exchange of gases between the ocean and atmosphere, disrupting the flow of gases such as CO₂, which is crucial for climate regulation.” 

The scientist highlighted that “surfactants are not inherently environmental pollutants. These surface-active compounds often form naturally in marine environments as a result of biological activity.” 

Lennin Flórez Leiva, coordinator of the Oceans, Climate and Environment Research Group (OCA) at the University of A Coruña’s Institute of Marine Sciences, noted, “Surfactant levels in tropical coastal areas like the Gulf of Urabá estuary are three to four times higher than those found in the open ocean.” 

The professor highlighted that the project pinpointed the Atrato River as the main source of surfactants flowing into the Gulf of Urabá, but further study is needed to explore their specific characteristics. The elevated surfactant levels in this region, higher than elsewhere in the world, have direct effects on marine life. 

Mariana Ribas Ribas, from the Institute of Chemistry and Biology of Marine Environments at the University of Oldenburg, expressed, “Our collaboration with researchers from the Universidad de Antioquia has been extremely positive, particularly in supporting undergraduate theses. I consider it vital to nurture young researchers. Partnerships like this not only build local expertise but also enhance scientific research as a whole.” 

An experience beyond academics 

The research appeared in the scientific journal Estuarine, Coastal and Shelf Science. It features Karen Moreno Polo and Diomer Tobón Monsalve as lead authors; both recently graduated from the Oceanography program at the Universidad de Antioquia (UdeA). The team also included Professor Ribas, Professor Flórez, researchers Carola Lehners and Oliver Wurl from the University of Oldenburg, and Wilberto Pacheco from the OCA research group. 

Karen Moreno Polo highlighted how this project helped her connect her academic goals with her research interests—something she initially felt uncertain about. She explained, “When they introduced us to this topic and I saw its close link to the carbon cycle, which holds significant scientific importance due to its impact on our lives, I couldn’t refuse. That’s how my exploration of that thin ocean layer began.” 

The researcher recognized the complexity of studying the ocean’s surface microlayer. Moreno Polo explained, “This zone represents the interface between ocean and atmosphere, and its location in a coastal area adds terrestrial influences. These factors make understanding what seem like small processes challenging, given their strong links to other environmental systems.” 

He noted that the challenge arose during the COVID-19 pandemic in 2020, which forced a pause in fieldwork for several months. During that period, however, the team focused on thoroughly reviewing the existing literature. 

Diomer Tobón Monsalve stressed the importance of studying the SML. “We must uncover what occurs within the microlayer. It affects everything from microfauna to climate systems, but researchers have not yet used it to study or model climate processes,” he explained. 

He noted that this study breaks new ground in the Gulf of Urabá ecosystem and tropical estuaries, leaving many questions for future research to answer. “We still don’t know where the surfactants come from—whether they form naturally, arise from biological activity, or stem from human influence. We also need to understand the microlayer’s biology and its link to surfactants, along with the physical processes occurring in deeper ocean waters beneath the microlayer,” he explained. 

He explained, “The ocean absorbs a large share of atmospheric CO₂. When the SML limits gas exchange, the ocean absorbs less CO₂, leaving higher levels of the gas in the atmosphere than previously thought. It could amplify the effects of climate change.” 

In a similar vein, Professor Mariana Ribas Ribas highlighted, “Future studies need to focus on understanding surfactants’ role in coastal systems like the Gulf of Urabá, which have received little attention in the literature. Gaining this insight is vital for refining our carbon budgets—average emissions per person—and other biogeochemical cycles.” 

Professor Lennin Flórez emphasized that the project’s success relied on the dedication of the undergraduate students, the expertise of the European scientists, and the strong support from both teams. “Above all, the tireless efforts of the students made this research possible,” he said.