The health of freshwater ecosystems like lakes and rivers is essential to our existence, but freshwater quality is declining due to human impacts like pollution and land use change. Developing a better understanding of the state of freshwater systems is imperative to shaping the focus of future efforts to restore their health, particularly in the face of climate change.  

Trent University Professor and Canada Research Chair in Climate Change and Northern Ecosystems, Dr. Andrew Tanentzap, and co-author Dr. Jérémy Fonvielle, University of Cambridge, highlight a more comprehensive approach to study freshwater health in their new article published in the prestigious journal Science. Their new approach focuses on tracking the fate of individual compounds dissolved in freshwater. 

Research suggests that many aspects of freshwater health depend on the composition of dissolved organic matter (DOM) found in water. DOM, a makeup of thousands of individual carbon compounds, mainly originates from the remains of plants and animals surrounding freshwaters, but also comes from organisms found in water, like fish and algae. 

Using past approaches to measure DOM, researchers could only determine the state of freshwater health, such as if a waterbody was polluted. However, these past approaches have been unable to pinpoint the origins and fate of individual compounds. Compounds vary in their characteristics, including how they react with drinking water treatment, absorb pollutants, and cause microorganisms to release greenhouse gases like carbon dioxide. Knowledge of individual compounds is important to improve freshwater health, such as by more accurately pinpointing sources of phosphorus and nitrogen pollution.  

Dr. Tanentzap uses Trent University’s Fourier-transform ion cyclotron resonance mass spectrometer (FT-ICR-MS) to track freshwater health. This unique technology provides new insights into water quality, allowing researchers to identify and investigate the tens of thousands of individual compounds found in water. 

“By measuring the chemical diversity in the water, we can also track the impact of climate change and its implications for the things we care about in water, like drinking water quality,” says Dr. Tanentzap. 

“At Trent University in our Water Quality Centre, we’re fortunate to have a FT-ICR-MS. The one at Trent is only the third of its kind in all of Canada, and it’s a powerful instrument that provides us with the resolution to be able to go out and track all of those individual compounds.” 

The use of the FT-ICR-MS can help, for example, distinguish the source of the pollutants, whether it be from agricultural work or wastewater, by creating a unique “fingerprint” of different types of DOM. 

Dr. Tanentzap says, “With the high-resolution techniques that we now have at our disposal, we can identify the precise sources that degrade water quality so we can make the changes we need to improve and protect freshwater.”