Baseline isotope data for Spirodela sp.: nutrient differentiation in aquatic systems.

The excessive addition of nitrogen to watersheds is recognized as one of the main causes of the global deterioration of aquatic ecosystems and an increasing number of studies have shown that δ¹⁵N signatures of macrophytes may reflect the N-loading of the system under investigation. This study investigated isotopic equilibration rates and concentration level effects of KNO₃ and cow manure nutrient solutions on the δ¹⁵N and δ¹³C signatures, C/N ratios, % N and % C of Spirodela sp. over time, to determine the feasibility of their use in monitoring anthropogenic N-loading in freshwater systems.