Notice Board

The Department of Geography & Environment hosts a series of guests, faculty members, and graduate students/post-docs who speak on current topics and issues in (or related to) human and physical geography.

From the Mountains to the Sea: Organic matter cycling in aquatic networks
Dr. Sarah Ellen Johnston

Friday, January 29th at 3:10 p.m.
Join us on Zoom

Agriculturalization, urbanization, and climate warming all have profound impacts on our natural aquatic environments. Important to understanding the impacts of these changes is how the carbon cycle is responding to human induced changes. Dissolved organic matter (DOM) is a complex mixture of organic molecules found in all aquatic environments and is an important piece of the carbon cycle. Changes in DOM provide us with an opportunity to better understand how a variety of mechanisms impact the carbon cycle. The composition of DOM is a chemical fingerprint of the sources of carbon in aquatic systems since different sources impart unique chemical signatures on the DOM. Across environments, from isolated Arctic lakes to the heavily agriculturalized grassland rivers in Southern Alberta, the composition of DOM can indicate how these systems are responding to human changes. My research uses techniques that detect specific chemical fingerprints of the DOM, which helps to track changes in the aquatic carbon cycle across diverse environments and gradients of human impact. Here I will present updated estimates DOM flow and composition from rivers in Alaska, Russia, and Alberta draining a variety of land cover types and human impacts, and how chemical changes in DOM composition can help explain the factors controlling this movement of carbon.

Everyone is welcome.  Free Admission.  
For further information, contact the University of Lethbridge at 403-329-2225

This lecture is made possible through an endowment established by donations from the Lethbridge Historical Society and Friends of Alex Johnston.