Source Molecular Talks About Nutrient Source Tracking at Great Lakes Conference

Source Molecular Corporation’s James Herrin spoke about nutrient source tracking at the 61st Annual Conference on Great Lakes Research, held from June 18 to June 22 at the University of Toronto Scarborough.

Mr. Herrin’s presentation is titled, “Identifying Nutrient Pollution Sources with Stable Isotopes to Improve Water Quality.” The conference was hosted by the International Association for Great Lakes Research (IAGLR), a scientific organization made up of researchers studying the Laurentian Great Lakes, other large lakes of the world, and their watersheds, as well as those with an interest in such research.

Mr. Herrin explains that nutrient source tracking is a method used to determine the sources of nutrient pollution in the environment. There are many potential sources of nutrients in the water — manure and animal waste, atmospheric deposition, chemical fertilizers, urban runoff and wastewater treatment plant discharge.

Millions of dollars have been spent to reduce nutrients but they continue to be a leading cause of impairment. Thus, stakeholders need to gain a better understanding of the sources of nutrient pollution. Specifically, where did the nitrogen that’s causing excessive nutrient loading come from? Nitrogen isotopes are effective tracers of nutrient source identification. Different sources of nutrients have distinctive isotope ratios and these serve as unique markers in order to trace them.

According to Mr. Herrin, crafting a nitrogen source tracking plan begins with developing an initial hypothesis for the nitrogen source. Next, sampling sites must be identified. Samples must be collected at nitrogen hotspots and must represent the watershed’s spatial variability. They must also be collected in wet and dry weather. There should be a substantial number of sampling events to represent temporal variability. Samples should be tested for anthropogenic sources and for the most likely natural sources.

The four-day conference featured 56 sessions with 580+ presentations and a Poster Social with 140+ posters. Several workshops and discussions offered the opportunity for a deeper dive into certain topics.

For more information about nutrient source tracking and to get a copy of the presentation, please contact James Herrin at