About

As a PhD student at the University of Waterloo, I am innovating approaches to apply in situ denitrification to reduce nitrate concentrations in aquifers. I am using this website as a repository for my studies and development of the scientific basis and methods to implement in situ treatment. In situ treatment of nitrate is advantageous since above ground nitrate treatment systems are more costly than treating contaminated groundwater in the aquifer.

Denitrification

Denitrification is a process that results in the breakdown of nitrate in less harmful products. This website is dedicated to the study of denitrification, nitrate, and agricultural land management practices.

Nitrates and Groundwater

Groundwater is polluted globally by nitrogen-based fertilizers and manure applications that facilitate plant growth. Excess nitrogen that is not taken up by plants is lost to the environment through surface runoff or leaching to groundwater. Nitrogen that is lost to surface runoff ends up in lakes, rivers, and oceans where it contributes to eutrophication. Nitrogen that is lost to leaching can convert to nitrate in the soil prior to advancing to groundwater.

Best or beneficial management practices (BMPs) as a method of groundwater quality control in agricultural settings have been a focus of environmental research for several decades. It is well documented that growing agricultural operations, which necessitate manure management and crop fertilization, have resulted in non-point source contamination of regional aquifers (Nolan and Stoner, 2000; Nolan and Hitt, 2006; Burrow et al. 2010). Of particular concern is contamination by nitrate, which, when present in drinking water in concentrations exceeding 10 milligrams per liter (mg/L), has been linked to serious health adversities, including methemoglobinemia (e.g., Gelberg et al. 1999), gastro-intestinal cancers (e.g., Ward et al. 1996), and congenital defects (Blaisdell et al. 2019).

BMPs implemented for the purpose of nitrate reduction in groundwater include crop fertilizer reduction, changes to the timing of fertilizer application, alternative methods of fertilization, strategic crop rotation and irrigation, and off-site manure storage. While BMPs have been adopted more widely in recent years, communication barriers between growers and policymakers, as well as growers’ concerns of financial deficit resulting from changes to often long-standing farming practices, prevent the adoption of BMPs in many cases (Feichtinger et al. 2008; Ranjan et al. 2019).

The effectiveness of agricultural BMPs, while demonstrated using predictive models (e.g., Bailey et al. 2015; Haas et al. 2017; Schultz et al. 2018), are very challenging to quantity on a regional scale using long-term in-situ measurements from a variety of fields and soil conditions. Confounding variables including regional geology, preferential flow paths, groundwater recharge dynamics, non-uniform distribution of natural attenuation capacity, and the time delay associated with BMP implementation and realized groundwater effects, all present significant challenges in determining how effective a BMP or combination of BMPs has been. Additionally, few regions have data available over a time period that is long enough to reasonably assess BMP effectiveness. Hence, the common use of modeling approaches.