May 4, 2015—
By Mark Wilcox
Research indicates human activities have altered the global nitrogen cycle as much or more than the global carbon cycle. Yet it seems the public is far less aware of these changes.
In the world of aquatic biology, it’s a long-held belief that what goes up, must come down. As human activity causes nitrogen loads to go up along the banks of rivers and streams, nitrogen levels go down through another process. Amy Marcarelli, a Michigan Technological University associate professor in biological sciences, has received a CAREER Award from the National Science Foundation (NSF) to study this nitrogen conversion balance.
She’s looking at two biological processes: nitrogen fixation and denitrification. Nitrogen fixation is sort of like a magic show where microbes take nitrogen out of thin air, turning it into a usable form for all organisms. The trick is in the biogeochemical process, which partitions and cycles chemical elements and compounds between the living and nonliving parts of an ecosystem. The process is more or less reversed in denitrification, with the gases released into the atmosphere. The result should be a net reduction in nitrogen loads in rivers and streams. Although nitrogen fixation could offset nitrogen losses from denitrification, we know little about where and when it occurs in streams and rivers, and how it responds to human activities.
Marcarelli is looking to apply updated analytical techniques and models to test alternative hypotheses regarding how the balance between nitrogen fixation and denitrification influences nitrogen loads in streams and rivers.
With funding from the CAREER award, Marcarelli and her team will help create more accurate nitrogen budgets and models which are needed to better understand and manage the human effects on nitrogen cycling at both regional and global scales.
The CAREER awards are prestigious grants from the NSF to young faculty who effectively integrate research and teaching. Marcarelli was awarded a 5-year, $794,661 grant to continue her research into nitrogen fixation and denitrification.
Not only will her research look to affirm, or disprove, long-held beliefs, but also to create a more ecologically-savvy citizenry by integrating ecosystem ecology techniques into K-12 and undergraduate education.