Grant: Strategic Projects - Group

Nitrogen is essential to plant growth but release of excess nitrogen (N) to surface waters results in elevated levels of nitrate (NO3) and ammonium (NH4) that can be harmful to aquatic organisms and threaten water supplies.  Excess nitrogen also results in the production of nitrous oxide (N2O), a potent greenhouse gas with a global warming potential of approximately 300 times that of CO2. Aquatic systems impacted by high nutrient loading from agriculture and wastewater treatment plants (WWTPs) are large sources of N2O to the atmosphere. No estimates exist for N2O emissions from Canadian rivers yet river emissions from WWTPs and agriculture are reported under Canada's UNFCCC (United Nations Framework Convention on Climate Change) and Kyoto commitments. Our goal is to determine the importance nitrogen sources and processes leading to elevated NO3 and NH4 levels in rivers and determine the magnitude and sources of N2O flux to the atmosphere from rivers.  We will focus on the largest Canadian watershed feeding Lake Erie, the Grand River, where several agencies and regulators require information for science-based management. The Grand River watershed is home to 900,000 people.  Projected population increase is over 40% within 20 years.  Currently, more than 500,000 people rely on the Grand River for drinking water while there are 26 WWTPs along the river.  Non point source nutrient loads are also extremely high, as agriculture (including large livestock operations) is the dominant land use.  To accommodate this new growth, billion dollar decisions for wastewater and drinking water treatment and agricultural land management must be taken in the immediate future. This research project involves a comprehensive approach to understanding and modelling the entire N cycle in rivers..  We will use year round field sampling, laboratory experiments and new natural isotopic techniques developed by our research group to understand the important processes of N cycling and to separate agricultural from WWTP contributions to high levels of N2O, NO3 and NH4 in rivers.