We’re coasting through tropical waters—the sun is bright, the sky is blue, and the temperature is balmy—but Karyn Rogers (above), a microbial geochemist from the Carnegie Institute of Washington, is bundled up in a thick sweatshirt, pants, and a wooly hat.
This is because Karyn spends much of her time processing samples in the cold room, a refrigerated mini-lab kept at a chilly 4 degrees C.
Why the cold room? Karyn and her collaborators are looking at redox (reduction/oxidation) chemistry in the water surrounding and inside of deep-sea microbial mats. Redox-sensitive chemical ions, like ferrous iron (Fe 2+), tend to react quickly with oxygen when brought to the surface, causing key information about the biogeochemical system to disappear. The cold temperature slows down these reactions, allowing Karyn to capture the chemistry in a state that’s as close to in situ conditions as possible.
Although previous research has addressed other components of water chemistry at hydrothermal vents, most studies don’t look at redox-sensitive chemistry in these deep-sea environments precisely because it’s so difficult to process before it reacts with oxygen in the air. Samples come up from the seafloor in bulk rather than one at a time, meaning there’s always a mad rush to get everything processed before it’s too late.
But Karyn is willing to brave the cold temperatures and labor-intensive sample processing because redox chemistry is such a crucial component of the ecosystems that we’re here to study, where many of the microbes live by oxidizing ferrous iron from the hydrothermal vent waters. Karyn’s efforts (and heroic sacrifice of personal comfort) will help to develop a better understanding of the interplay between microbial diversity and geochemical diversity in extreme environments.
–Cat Wolner, NSF
Photo credits: Cat Wolner