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Temperature and nitrogen modulated nitrous oxide cycling

Project Description

A postgraduate research studentship is available to start in September 2019 in the group of Professor Mark Trimmer, based in the School of Biological and Chemical Sciences at Queen Mary University of London.

Project details

Nitrous oxide (N2O) is an atmospherically potent gas, with 300 times the global warming potential of CO2 and playing a major role in the destruction of stratospheric ozone. Not surprisingly therefore, research so far has tended to focus on important sources of this potent gas. For example, agricultural soils and estuaries with their high loadings of human derived nitrogen (fertilizers, sewage) are often associated with high emissions of N2O. Recently, as part of our work in pristine parts of the Arctic, we have unearthed evidence for a little explored sink for N2O. Here, across geothermally heated streams we found that colder streams contained less N2O relative to atmospheric equilibration, while the warmer streams contained more. Bio-available, fixed-N is scarce and these pristine stream ecosystems are fuelled by an abundance of N-fixing, diazotrophs which readily fix N2 gas. The ecological problem here though is that N2 fixation is very energy demanding and fixing N2 in the cold is energetically costly. In contrast, N2O is partially activated relative to N2 and fixing it should be energetically more favourable in the cold. Here the primary objective is to characterise the fundamental microbial ecology and biogeochemical significance of this novel sink for N2O. The PhD student will use 15N incubations to trace the fixation of both 15N2 and 15N2O into microbial community biomass – bulk and their DNA – as a function of temperature. They we will then use 15N and 13CO2 stable-isotope-probing (SIP) combined with taxonomic marker gene sequencing and functional metagenomics to identify whether this N2O fixation represents a physiological response at cooler temperatures - in otherwise N2 fixing organisms - or whether there is an entirely novel, N2O sustained, microbial community. The PhD will involve fieldwork in remote settings including periods in Iceland and the northern uplands of both Scotland and England.

Eligibility and applying

Applications are invited from candidates with, or expecting to be awarded, a first or an upper-second class bachelors degree in a relevant subject area. An MSc in an appropriate subject may be an advantage. Knowledge of bioelement cycling in ecology and the application of tracers e.g. 15N and 13C is desirable and/or some microbiological knowledge or experience.

Applicants from outside of the UK are required to provide evidence of their English language ability. Please see our English language requirements page for details:

Informal enquiries about the project can be sent to Professor Mark Trimmer (). Formal applications should be submitted online by the stated deadline. Please use the ’visit website’ link below to access the online application form.

Funding Notes

The studentship is funded by the Leverhulme Trust. It will cover Home/EU tuition fees and provide a tax-free maintenance allowance for 3 years at the Research Council rate (£17,009 in 2019/20)


[1] Farias, L. et al. Biological N2O Fixation in the Eastern South Pacific Ocean and marine cyanobacterial cultures. PLoS ONE 8, doi:10.1371/journal.pone.0063956 (2013).
[2] Welter, J. R. et al. Does N-2 fixation amplify the temperature dependence of ecosystem metabolism? Ecology 96, 603-610, doi:10.1890/14-1667.1 (2015).
[3] Yvon-Durocher, G., Hulatt, C. J., Woodward, G. & Trimmer, M. Long-term warming amplifies shifts in the carbon cycle of experimental ponds. Nature Climate Change 7, 209-+, doi:10.1038/nclimate3229 (2017).

How good is research at Queen Mary University of London in Biological Sciences?

FTE Category A staff submitted: 23.39

Research output data provided by the Research Excellence Framework (REF)

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