Scientists Reveal How Iron Minerals Lock Carbon in Soil for Centuries
Scientists have uncovered how iron minerals store carbon in soil for decades and even centuries. This discovery explains an important part of the global carbon cycle. As a result, it helps scientists better understand how soils reduce greenhouse gas emissions.A new study from Northwestern University focused on iron oxide minerals, which are abundant in soils worldwide. These minerals prevent carbon from returning to the atmosphere. However, researchers previously lacked details about exactly how carbon is retained.
The Role of Ferrihydrite in Carbon Storage
Iron oxide minerals, including ferrihydrite, store over one-third of soil organic carbon. Therefore, they play a critical role in long-term carbon storage. Ferrihydrite is commonly found near plant roots and in organic-rich sediments. It interacts with many types of organic molecules, including amino acids, sugars, and nucleotides.The mineral’s surface is complex. It carries an overall positive charge, but its surface contains both positive and negative regions. This mixed charge allows ferrihydrite to attract different organic compounds. Some molecules attach through electrical attraction, while others form stronger chemical bonds with iron atoms. Hydrogen bonding also helps weaker compounds attach.
Multiple Binding Methods Keep Carbon Stable
Different organic compounds bind in different ways. Amino acids attach to opposite surface charges, while sugars bind through hydrogen bonds. This combination strengthens carbon retention in soil. As a result, carbon can remain stored for decades or even centuries. This process limits greenhouse gas release and supports climate stability.
This Discovery Matters
Soil stores approximately 2,500 billion tons of carbon, making it the second-largest carbon sink after oceans. Understanding how iron minerals trap carbon helps improve climate models. Scientists are now studying what happens to carbon after it binds to minerals. Some compounds may become even more resistant to breakdown over time, providing long-term environmental benefits.
