Diatoms, single-celled algae with ornate, glassy shells, are often admired for their stunning beauty. These algae play a vital role in ocean chemistry and ecology, contributing to climate regulation and marine food webs while they are alive. Now, new research reveals that their impact continues long after they die, rapidly reshaping ocean chemistry and potentially influencing Earth’s climate in ways previously underestimated.
The Unexpected Speed of Reverse Weathering
A team of scientists from Georgia Tech has discovered that diatoms’ silica-based skeletons transform into clay minerals surprisingly quickly—within just 40 days. Previously, scientists believed this process, known as reverse weathering, took hundreds to thousands of years. The findings, published in Science Advances, highlight the dynamic role these microscopic organisms play in regulating the planet’s climate.
From Glass to Clay: A Chemical Transformation
When a diatom dies, most of its silica skeleton dissolves. However, the remaining silica can undergo reverse weathering—a process that transforms it into new clay minerals containing trace metals. This process also releases previously sequestered carbon back into the atmosphere as sediments react with seawater. This interplay between silicon, carbon, and trace metals significantly influences ocean chemistry and helps stabilize Earth’s climate over time.
Recreating Seafloor Conditions in the Lab
To understand how and how quickly reverse weathering happens, the researchers built a specialized two-chamber reactor simulating seafloor conditions. One chamber contained diatom silica, while the other held iron and aluminum minerals, separated by a membrane that allowed dissolved elements to mix. Utilizing advanced microscopy, spectroscopy, and chemical analysis, the team tracked the full transformation from diatom shell dissolution to new clay formation.
The results were striking: within just 40 days, the diatom silica transformed into iron-rich clay minerals—the same minerals found in marine sediments. This demonstrates that reverse weathering isn’t a slow, background process, but an active component of the modern ocean’s chemistry, influencing silica availability, carbon dioxide levels, and nutrient recycling.
Implications for Climate Modeling and Ocean Ecosystems
“It was remarkable to see how quickly diatom skeletons could turn into completely new minerals and to decipher the mechanisms behind this process,” said Simin Zhao, the study’s first author.
The rapid transformation of diatoms has far-reaching implications. It suggests that ocean chemistry is more dynamic and potentially more responsive to modern environmental changes than previously thought. The findings also address a long-standing mystery: scientists have known that more silica enters the ocean than gets buried, and this research suggests that much of it is converted to new minerals through rapid reverse weathering.
“Diatoms are central to marine ecosystems and the global carbon pump,” explained Jeffrey Krause, co-author and oceanographer. “We already knew of their importance while living. Now we know that even after they die, diatoms’ remains continue to shape ocean chemistry in ways that affect carbon and nutrient cycling – a true game-changer.”
Future Research and a Reminder of Basic Science
The team’s research will guide climate modelers studying the ocean’s role in regulating atmospheric carbon, as well as improve models of ocean alkalinity and coastal acidification. Their next steps involve exploring how factors like water chemistry impact these transformations and examining samples from coastal and deep-sea environments to see how these laboratory findings translate to the natural world.
“This study changes how scientists think about the seafloor, not as a passive burial ground, but as a dynamic chemical engine,” said Yuanzhi Tang, senior author of the study.
The research serves as a powerful reminder of the importance of basic scientific inquiry and highlights how molecular-scale processes within tiny organisms can have profound impacts on Earth systems.
