Clumped isotopes as a novel tracer for the N2O cycle

Scientist Empa: Kristyna Kantnerova (PhD student, Prof. S. Bernasconi ETHZ)

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Nitrous oxide is a major greenhouse gas and the most important ozone destructing species emitted today. Its sources are disperse and highly variable which, combined with the long lifetime of N2O, makes source studies and thus mitigation challenging. Measuring the doubly substituted “clumped” isotopes of N2O will add new and unique dimensions to our ability to fingerprint and constrain the N2O biogeochemical cycle, as has been shown in recent years for other atmospheric constituents such as CO2, CH4, and O2.

Within this SNSF funded project, we are developing a quantum cascade laser based analytical technique for the selective and precise analysis of the most abundant doubly substituted N2O isotopic species: 15N14N18O, 14N15N18O, and 15N15N16O. The measurement setup will consist of a laser spectrometer coupled to a field deployable preconcentration device, capable of enhancing N2O mixing ratios from ambient or process levels to the percentage range.

Being a completely new and exciting field of research, analysis of clumped N2O isotopes offers a broad range of prospective applications. This will be demonstrated by testing exemplary research hypotheses on N2O produced by microbial, fungal and abiotic sources processes. In a larger perspective, this new technique may also be applied to other research areas such as stratospheric chemistry or industrial catalytic processes. With respect to biogeochemical N2O cycles, clumped N2O is expected to significantly advance our understanding by providing a new class of reservoir-insensitive approaches and molecular-scale insights.

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