Caroline Slomp

Caroline Slomp
I study Earth’s elemental cycles and their microbial and chemical controls. I specifically look at elements that are important to life.
Caroline Slomp
Conservation and Restoration Ecology
Current role

On 1 October 2022, prof. dr. ir. Caroline Slomp was appointed professor at the Radboud Institute for Biological and Environmental Sciences (RIBES). In this interview, you will learn more about her research and her activities at Radboud University. “We want to understand how natural systems function.”

Geomicrobiology and biogeochemistry: what is this field about?

“I study Earth’s elemental cycles and their microbial and chemical controls. I specifically look at elements that are important to life. I do this on different time scales: I look at present-day cycles, but also try to reconstruct elemental cycles in the geological past.”

What is an elemental cycle?

Elemental cycles are the biogeochemical pathways by which elements are transformed and moved through various states by biological, chemical and geological processes.

What topics are you working on right now?

“We study marine areas that suffer from a lack of oxygen near the seafloor. Oxygen depletion has all kinds of effects: for example, it impacts microbes, cycles of nutrients such as those of nitrogen and phosphate, and the dynamics of the greenhouse gas methane. Seas change dramatically when there is a lack of oxygen. Our goal is to unravel how the microbial and chemical processes and the interactions between the various elemental cycles change upon marine oxygen loss. A key question is how much methane produced in coastal environments escapes to the atmosphere."

“Ultimately, we are interested in how the ocean responds to environmental change. Such changes can be caused by natural processes, but can also be caused by humans. We want to understand both the natural drivers and the part that humans play, and how we can restore ecosystems.”

“By the way, I always say we, because we do this research in teams. I not only have my own team, but we also involve a large number of collaborators in each project. Collaborating is also one of the things I am looking forward to the most in my job at RIBES: my research matches RIBES’ mission: towards healthy ecosystems. I would like to collaborate with people working on present-day ecosystems and the various biological components in these. I would love to hear from colleagues who are interested in that!”

Which projects will you be working on, here at Radboud University?

“One of my projects, the ERC Synergy project MARIX, already started before I joined Radboud University. It is a collaboration with the department of Microbiology (with Mike Jetten, a.o.). It’s a very large project in which we study the removal of methane and ammonium from coastal areas.

In such coastal areas, most methane is produced in the seafloor. Most of that methane is removed by microbes – the microbial filter. But there are also places where methane is emitted to the atmosphere, which is harmful to the environment, because methane is a strong greenhouse gas. We want to understand how this microbial filter for methane works exactly. We already know some of the pathways responsible for the methane removal but we have indications there are additional ones and we want to know how they work and what microbes are involved. We are doing the same for ammonium removal. That is important because high levels of ammonium are toxic to marine life.”

“In our project, we’re specifically looking at coastal areas, because they are impacted by humans and by climate change. In comparison to the ocean, they are relatively small ecosystems that can easily be disrupted. The oceans are also changing due to human activity by the way, but that is a different story. We see that our Dutch coastal waters have strongly changed over the past couple of decades. This is also happening globally. In this project, we are studying a number of carefully selected sites. One of those is the Dutch Lake Grevelingen. During the COVID crisis, a location in the Netherlands was very practical, as it allowed us to continue our field studies. We are also working in Swedish and Finnish coastal waters.”

Field studies and other research methods

“Field studies are an essential part of our research. We do not just want to do theoretical work at our desk. We also do that, but in the end we want to know what it is like in the real world. And that is often surprising: beforehand, you form an image of a certain place, based on literature or your own expectations. Once you see the place in real life you often aresurprised. That is also because the world is changing, rather quickly actually.”

“Personally, I combine field studies (such as in the Arabian Sea, Baltic Sea, Mediterranean Sea, Gulf of Mexico, North Sea, and so on), experimental work, and modelling work. This fits with the research by environmental scientists and ecologists at RIBES. Moreover, I have talked about marine waters and the seafloor up till now, but I also study freshwater systems, which ties in with RIBES.”

What would you like to achieve with this project?

“We want to make mathematical models with which we can more accurately describe the chemistry and microbiology of coastal waters. Eventually, our goal is to develop models that can predict what happens with a coastal system when it is disturbed and  how quickly it can recover. Crucial to these models is the inclusion of the role of microbes. If you only look at systems from a chemical point of view, you see the net processes, so you do not know what is going on exactly. Once you know what microbes are present in a certain place and how active they are, you can begin to unravel what processes are truly going on.”

Will you also be teaching?

“In 2023, I will contribute to the MSc course Microbiology of Aquatic Ecosystems. Besides that, I would like to develop a course on Geobiology.  This fits with my research on geological time scales and is currently not really a part of the research at RIBES. Geobiology considers the relationship between the co-evolution of life and Earth. Elemental cycles are also an important part of this; just think of the appearance of oxygen in the atmosphere, 2.3 billion years ago. I have taught about the history of the Earth before and I am really looking forward to doing this again.”

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