Project Number:
DNR-219
Funding Year:
2013
Contract Period:
7/1/2013 - 6/30/2015
Funding Source:
DNR
Investigator(s):
PIs:- Paul M. McGinley, UW-Stevens Point
- William M. DeVita, UW-Stevens Point
- Amy Nitka, UW-Stevens Point
Abstract:
BACKGROUND
Nitrate-nitrogen concentrations exceed the drinking water standard in nine percent of Wisconsin’s private wells andforty-seven community water system wells. It has been estimated that up to ninety percent of the nitrogen that contaminates groundwater is from agricultural sources, but on-site wastewater systems may also be important sources of groundwater nitrate-nitrogen in some areas. It is important that the source of nitrate-nitrogen to an individual well be understood to make appropriate land management and treatment decisions.
OBJECTIVE
The objective of this study was to develop a chemical method for distinguishing between fertilizer and on-site waste sources of nitrate to a well by analyzing other compounds that are likely present in groundwater recharge from those sources.
METHODS
A group of likely tracers for on-site waste and agricultural nitrate contamination were identified through literature review and previous research. The ideal tracer is ubiquitous in the source water, mobile in groundwater, resistant to degradation and detectable at environmentally relevant concentrations. Analytical methods were refined to concentrate and analyze the on-site waste indicator compounds. That group included pharmaceuticals, artificial sweeteners and personal care products. Five pesticide metabolites and a bovine antibiotic were included as agricultural source indicators. Water samples were collected five times over two years from eighteen private wells in a suburban area with a history of nitrate-N 6 contamination. Two sets of monitoring wells were installed near the private wells to understand the vertical variation in water quality in the study area.