Environmental Controls on Bacterial Nitrogen Cycling

Supervisors: Dr Mark Osborn

Key words: inorganic nitrogen; microbial nitrate; estuaries

Project Description

Estuaries are major conduits for the transport of inorganic nitrogen (derived from fertilizer runoff and wastewater treatment plants) from land to sea. Estuarine sediments are now known to be a major site for the removal of inorganic nitrogen and in particular nitrate, via three distinct mechanisms of microbial nitrate/nitrite reduction (denitrification and anammox both yielding nitrogen, or nitrate ammonification yielding ammonium which remains in the system). Without such processes, increasing nitrate loads drive eutrophication in estuarine and coastal environments. However and conversely, denitrification can also result in the production of the greenhouse gas nitrous oxide, hence contributing to global warming.
Our previous research has shown diverse bacterial species drive these different nitrate reduction pathways and additionally that the fate of nitrate is affected by both biotic and abiotic variables and varies spatially and seasonally. The aim of this studentship is to determine how and to what extent key environmental variables including temperature, nitrate loads and the availability of organic carbon, including that derived from photosynthetic benthic algae/diatoms, affect and control the nitrate reduction pathways and hence the environmental fate of nitrate in estuarine sediments, and in addition how these factors affect the composition, function and activity of the nitrate reducing bacterial communities therein.
The successful applicant will undertake fieldwork in UK estuaries, and receive training in biogeochemistry and molecular microbial ecology.
Applicants should have, or expect to obtain at least a 2:1 degree in a relevant subject. Informal enquiries can be directed to Dr. Mark Osborn a.m.osborn@sheffield.ac.uk.

Starting date: 1 October 2010.

How to apply: Complete an on-line application form via University of Sheffield web site at http://www.shef.ac.uk/postgraduate/research/apply/index.html. Send a full CV, via email to Mrs S Carter, s.a.carter@sheffield.ac.uk, or a hard copy to Mrs S Carter, Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN.

Closing date for applications: 31 January 2010.