Research Areas > Nutrients > Identification of Nutrient Sources > Background: Isotope Geochemistry Tools

Background: Isotope Geochemistry Tools for Nutrient Source Tracking

SCCWRP Research

Isotopes are slightly different versions of the same element. For example, ¹⁴N and ¹⁵N are two isotopes of nitrogen that have most of the same properties, but differ in their number of neutrons, making them distinguishable through chemical analysis. An isotope is called “stable” if it does not decay spontaneously (is not radioactive). Because physical, chemical, and biological processes tend to preserve certain isotopes, they can serve as useful tools to track the source of an element in nature. Different sources of nutrients have unique isotope ratios, like fingerprints. Thus, quantifying the relative contribution of each isotope to the total provides a means to identify the sources of nutrients (such as manmade fertilizers or naturally decaying plants) for that particular ecosystem.

SCCWRP is exploring the use of isotope tools to track nutrient sources and characterize nutrient cycling within ecosystems. Scientists will examine the natural isotope forms of different nutrients (such as nitrogen and phosphorus) found in dissolved and particulate organic matter in ambient waters.