DEPARTMENT OF EARTH, ENVIRONMENTAL, AND PLANETARY SCIENCES

Marine biogeochemical cycles help regulate Earth's climate -- but what happens to them when oxygen becomes scarce? As our oceans warm, they’re losing dissolved oxygen. Areas with low dissolved oxygen, called oxygen minimum zones (OMZs), are expanding. This fundamentally alters important feedbacks between the ocean and Earth’s climate which help keep it regulated.

I study how biogeochemical cycling changes in oxygen-limited conditions. This includes examples from the geologic past, like the Ocean Anoxic Events of the Cretaceous, as well as unique, present-day environments, like a deep, stratified lake. I measure stable isotopes of common elements in water, sediments, and rocks to reconstruct biogeochemical changes that occur when dissolved oxygen is lower. I also use oxygen-sensitive trace elements in the ocean, like molybdenum, to track how oxygen levels have changed over time in marine environments.

As OMZs expand, this work will help us understand how cycling of critical elements like carbon, sulfur, and oxygen may change, and what that means for Earth’s climate in the future.