The effects of nitrogen pollutants on the isotopic signal (?15N) of Ulva lactuca. Microcosm experiments
Effects of two chemical forms of Nitrogen (NH4
+ and NO3
?) on ?15N in Ulva lactuca were analysed separately and
in mixture at two concentrations.We assessedwhether the ?15Nvaluesof U. lactuca discriminate between Nitrogen
from synthetic fertilisers (inorganic) and from fresh cow manure (organic), and the isotopic ability of the
macroalga to reflect Nitrogen concentrations. Isotopic signature and N content of themacroalga reflected different
nitrogenous sources and their concentrations after 48 h. The inorganic Nitrogen source (NH4NO3) altered the