Fingerprint natural soil N2O emission from nitration and denitrification by dual isotopes (15N and 18O) and site preferences

Nitrification and denitrification are the main contributors to soil N2O production and emission, and distinguishing their contributions to N2O emission under natural conditions is vital to deciphering nitrogen biogeochemistry. Stable isotopes have provided insight to resolve this problem, of which δ15N2Obulk (15N abundance in N2O), dual isotopes (δ15N, δ18O) and site preference (SP) are the most effective methods currently. δ15N2Obulk is useful in tracing substrates yielding N2O, but it is helpless to make accurate differentiation between nitrification and denitrification; The dual isotopes, δ15N and δ18O, introduce O atom sources in partitioning N2O source and this method could roughly apportion N2O from nitrification and denitrification. However, expensive equipment requirements and the inherent uncertainties on δ18O determination owning to few data available hamper its accuracy and applicability on distinguishing nitrification and denitrification. Site preference (SP) provides new insight on distinguishing contribution of nitrification and denitrification on N2O emission and results in more accuracy results. We summarized that the average values of δ15N2Obulk, δ18O and SP during denitrification, which were − 29.29‰, 19.78‰, and 2.43‰, respectively, are much lower than the corresponding values during nitrification, which were − 7.87‰, 48.03‰ and24.14‰, respectively.