Nitrite isotope characteristics and associated soil N transformations

Nitrite (NO(2)(−)) is a crucial compound in the N soil cycle. As an intermediate of nearly all N transformations, its isotopic signature may provide precious information on the active pathways and processes. NO(2)(−) analyses have already been applied in (15)N tracing studies, increasing their interpretation perspectives. Natural abundance NO(2)(−) isotope studies in soils were so far not applied and this study aims at testing if such analyses are useful in tracing the soil N cycle. We conducted laboratory soil incubations with parallel natural abundance and (15)N treatments, accompanied by isotopic analyses of soil N compounds (NO(3)(−), NO(2)(−), NH(4)(+)). The double (15)N tracing method was used as a reference method for estimations of N transformation processes based on natural abundance nitrite dynamics. We obtained a very good agreement between the results from nitrite isotope model proposed here and the (15)N tracing approach. Natural abundance nitrite isotope studies are a promising tool to our understanding of soil N cycling.