Human Disturbance to Land Releases “Old Carbon” into Rivers

Dr. Marguerite Xenopoulos

Trent University, January 6, 2015

Mobilization of “old carbon” comparable to effects of burning fossil fuels

A new study, co-authored by Trent University Biology professor Dr. Marguerite Xenopoulos, and published in the new issue of Nature Geoscience, has found that human disturbance to land is causing the release of “old carbon” into rivers and waterways, the negative effects of which are equated to the burning of fossil fuels.

“Soils store carbon over long periods of time. However, new research suggests that the effects of human land-use such as urban development and intensive agriculture and monocultures —are reducing how much carbon is stored in the ground,” explains Professor Xenopoulos. “When humans manipulate the land, the “old” stored soil carbon is released in nearby waterways, rivers and streams. The release of this aged carbon is comparable to the burning of fossil fuels.”

Prof. Xenopoulos co-authored the study with lead author Professor David Butman from the University of Washington, Professor Rebecca Barnes from Colorado College, Dr. Henry Wilson, a Trent University alumnus and current research scientist with Agriculture and Agri-Foods Canada, and Professor Peter Raymond from Yale University. Dr. Wilson completed his Ph.D. in the Watershed Ecosystems Graduate Program (now Environmental and Life Sciences) at Trent University in 2009.

The new paper in Nature Geoscience, called “Increased mobilization of aged carbon to rivers by human disturbance,” shows for the first time that the carbon in rivers with human affected land use (agriculture, urban) is aged (old), as determined through the use of carbon radioisotopes.

“Using data from southern Ontario coupled with a global dataset from field research around the world the study determined how carbon isotopes of organic matter in rivers can be linked to the impact of land disturbances—specifically, the release of ‘old’ previously stored carbon into the modern carbon cycle” says Prof. Xenopoulos. “Typically, in more pristine rivers most carbon would originate from newly formed and produced carbon from soils, and nearby plants and trees, but the results of this study suggest that up to nine percent of that organic carbon is actually aged carbon that human land disturbances have mixed back into the cycle.”

Through Professor Xenopoulos’ Natural Sciences and Engineering Research Council (NSERC) Discovery grant program, the study involved about a dozen river catchments in southern Ontario that span a gradient of agriculture land use.


About Trent University

One of Canada’s top universities, Trent University was founded on the ideal of interactive learning that’s personal, purposeful and transformative. Consistently recognized nationally for leadership in teaching, research and student satisfaction, Trent attracts excellent students from across the country and around the world. Here, undergraduate and graduate students connect and collaborate with faculty, staff and their peers through diverse communities that span residential colleges, classrooms, disciplines, hands-on research, co-curricular and community-based activities. Across all disciplines, Trent brings critical, integrative thinking to life every day. As the University celebrates its 50th anniversary in 2014/15, Trent’s unique approach to personal development through supportive, collaborative community engagement is in more demand than ever. Students lead the way by co-creating experiences rooted in dialogue, diverse perspectives and collaboration. In a learning environment that builds life-long passion for inclusion, leadership and social change, Trent’s students, alumni, faculty and staff are engaged global citizens who are catalysts in developing sustainable solutions to complex issues. Trent’s Peterborough campus boasts award-winning architecture in a breathtaking natural setting on the banks of the Otonabee River, just 90 minutes from downtown Toronto, while Trent University Durham delivers a distinct mix of programming in the GTA.

For more information contact:

Dr. Marguerite Xenopoulos, associate professor, Biology, Trent University, 705-748-1011 ext. 7699 or  


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