We are pleased to announce the publication of a new article in Groundwater Monitoring and Remediation from the G360 Institute Team.
On methods for in-well nitrate monitoring using optical sensors.
MacDonald*, G., Levison, J., Parker, B.L.
DOI: 10.1111/gwmr.12248
Acknowledgments
The authors would like to acknowledge the Canadian Foundation for Innovation (CFI), Ontario Research Fund: Small Infrastructure, Ontario Research Fund Research Excellence Round 3 Award ORF-RE 03-061 (ORF RE-3), The Canadian Natural Sciences and Engineering Research Council (NSERC) and the University of Guelph School of Engineering for financial support of this research. Norfolk County, the Region of Waterloo and City of Guelph are acknowledged for providing access to wells/field sites. Bill Banks of Banks Groundwater Engineering Ltd. provided valuable technical input throughout the research and is gratefully acknowledged.
Funding
University of Guelph School of Engineering
Canadian Natural Sciences and Engineering Research Council
Small Infrastructure, Ontario Research Fund Research Excellence Round 3. Grant Number: ORF-RE 03-061
Canadian Foundation for Innovation (CFI)
Abstract:
Optical sensors are promising for collecting high resolution in-well groundwater nitrate monitoring data. Traditional well purging methods are labor intensive, can disturb ambient conditions and yield an unknown blend of groundwater in the samples collected, and obtain samples at a limited temporal resolution (i.e., monthly or seasonally). This study evaluated the Submersible Ultraviolet Nitrate Analyzer (SUNA) for in-well nitrate monitoring through new applications in shallow overburden and fractured bedrock environments. Results indicated that SUNA nitrate-N concentration measurements during flow cell testing were strongly correlated (R 2 = 0.99) to purged sample concentrations. Vertical profiling of the water column identified distinct zones having different nitrate-N concentrations in conventional long-screened overburden wells and open bedrock boreholes. Real-time remote monitoring revealed dynamic responses in nitrate-N concentrations following recharge events. The monitoring platform significantly reduced labor requirements for the large amount of data produced. Practitioners should consider using optical sensors for real-time monitoring if nitrate concentrations are expected to change rapidly, or if a site’s physical constraints make traditional sampling programs challenging. This study demonstrates the feasibility of applying the SUNA in shallow overburden and fractured bedrock environments to obtain reliable data, identifies operational challenges encountered, and discusses the range of insights available to groundwater professionals so they will seek to gather high resolution in-well monitoring data wherever possible.