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School of Biological and Behavioural Sciences

Yueyue Si


PhD student



Project title: Novel sinks for the atmospherically potent gas nitrous oxide

Summary: Nitrous oxide is an atmospherically potent gas, having 350 times the warming potential of CO2 and destroying stratospheric ozone. Recently, in pristine, nitrogen limited parts of the Arctic, we have unearthed evidence for a novel sink for N2O. Here, our primary objective is to characterise the fundamental microbial ecology and biogeochemical significance of this novel sink for N2O. We will work in both the controlled setting of our long-term experimentally warmed ponds, and along the temperature gradient of geothermally heated streams in Iceland to test:

  1. whether at colder temperatures a higher proportion of total N-fixation is dependent on N2O. Since N2O is partially activated relative to N2 and fixing it should be energetically more favourable in the cold;
  2. whether the diazotrophs responsible for N2O fixation will be taxonomically distinct from those fixing N2 – or, alternatively, N2O-fixation represents a physiological response at cooler temperatures in diazotrophs that typically fix N2. 



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