Texas A&M University Graduate Student Spotlight: Iron Colloids

Iron Colloids

How long can you hold your breath? 30 seconds? A full minute, maybe longer? Oxygen in the air we breathe is an essential component of chemical reactions in our bodies that keep us alive. Oxygen is produced as a byproduct of photosynthesis, the chemical pathway by which plants make food for themselves using energy from the sun. Only about half of the oxygen in the air comes from land plants, however; you can thank microscopic marine plants, called phytoplankton for the other half.

To photosynthesize, phytoplankton need iron. Just like humans need vitamins and minerals to be strong, phytoplankton need iron to perform basic metabolic functions. Dissolved iron is considered bioavailable for phytoplankton to use for photosynthesis, and a significant portion of this dissolved iron is considered to be colloidal, which means that instead of being truly dissolved, the iron is actually present as tiny particles that are so small that they do not sink.  Using a new method that separates colloids in to a spectrum of sizes, scientists at Texas A&M can learn a lot about the composition of these colloids and structure of colloids, including their origin and chemical processes that affect them. Answering these questions about colloids along with learning about coastal processes such as plankton blooms, ocean currents, and river runoff, can give insight into the role that iron colloids play in the marine environment and just how important they may be for phytoplankton growth.  Understanding how iron colloids impact phytoplankton can provide important insights regarding marine ecosystems such as the dynamics of fish populations and climate change, which are linked to the marine phytoplankton.

The above figure shows the size separation of different iron pools in the oceans; soluble (dissolved), colloidal, or particulate. Image provided by Kimber De Salvo


This has been On the Ocean: a program made possible by the Department of Oceanography and a production of KAMU-FM on the campus of Texas A&M University in College Station.  For more information and links, please go to ocean.tamu.edu and click On the Ocean

Script Author: Kimber De Salvo

Editor: James M. Fiorendino

Contributing Professor: Dr. Kathryn Shamberger