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Award details

Ammonia (NH3) in the marine atmosphere and impact on aerosols DTP Research Theme(s): Changing Planet NERC GW4+ DTP PhD studentship for 2022 Entry, PhD in Biosciences Ref: 4299

About the award


Lead Supervisor

Dr Ming-Xi Yang - Plymouth Marine Laboratory

Additional Supervisors

Dr. Jo Browse -College of Life and Environmental Sciences, University of Exeter.

Dr Tom Bell - Plymouth Marine Laboratory.

Mr. Malcolm Woodward - Plymouth Marine Laboratory 

Location: Penryn Campus, University of Exeter, Falmouth, Cornwall.

This project is one of a number that are in competition for funding from the NERC Great Western Four+ Doctoral Training Partnership (GW4+ DTP).  The GW4+ DTP consists of the Great Western Four alliance of the University of Bath, University of Bristol, Cardiff University and the University of Exeter plus five Research Organisation partners:  British Antarctic Survey, British Geological Survey, Centre for Ecology and Hydrology,  the Natural History Museum and Plymouth Marine Laboratory.  The partnership aims to provide a broad training in earth and environmental sciences, designed to train tomorrow’s leaders in earth and environmental science. For further details about the programme please see

For eligible successful applicants, the studentships comprises:

  • An stipend for 3.5 years (currently £15,609 p.a. for 2022/23) in line with UK Research and Innovation rates
  • Payment of university tuition fees;
  • A research budget of £11,000 for an international conference, lab, field and research expenses;
  • A training budget of £3,250 for specialist training courses and expenses

Project details:

PMLs new L4 mooring

PMLs Penlee Point

Project Background:

Atmospheric particles (aerosols) are key to the Earth’s climate and affect air quality. Ammonia (NH3) is one
of the principal precursor gases to aerosols (forming particulate ammonium, NH4+) and the primary base in
the atmosphere, neutralising acids and facilitating new particle formation. Over the last few decades,
pollution regulations (e.g. Clean Air Acts) have significantly reduced the emissions of acidic aerosol
precursors in Europe and North America, including sulphur and nitrogen oxides emitted from fossil fuel
combustion. However, NH3 emissions, driven largely by agriculture, have hardly decreased. This has
resulted in long-term changes in aerosol pH and chemistry that are not well understood. Additionally, we
lack understanding of natural NH3 sources. Oceanic NH4+ may be a key source of NH3 to the marine
atmosphere, depending on biogeochemistry, water temperature and water pH. Estimates of air-sea NH3
flux on a regional/global scale are severely hampered by a) a paucity of marine atmospheric NH3
observations, and b) a lack of mechanistic studies of air-water NH3 exchange processes. As a result, NH3 is
not well represented in global climate models and its impact is poorly constrained or neglected.

Project Aims and Methods:

It is envisaged that this PhD project will combine long-term ambient observations, laboratory experiments,
and an Earth System Model to significantly improve our understandings in atmospheric NH3 cycling, oceanic
NH3 emissions, and the impact of NH3 on aerosols. The student is encouraged to define the proportional
focus of the PhD. Some examples of research questions may be:
1. What are the concentrations of atmospheric NH3 and aerosol NH4+in different airmasses (e.g.
marine Atlantic, mainland Europe, Arctic) and how do they vary seasonally?

2. Does air-sea NH3 exchange behave as predicted according to existing theory (as a function of water
temperature and pH) and is the ocean a large source of NH3 to the marine atmosphere?

3. What are the impacts of (ocean-derived) NH3 on marine aerosols and clouds?

4. How will oceanic NH3 emission change in the future and what feedback may that have on marine aerosols, clouds and climate?

Candidate Requirements:

Suited for someone with a passion for environmental research with an aptitude to adapt/operate scientific
instrumentation and have interests in quantitative data analysis/numerical modelling. Applicants should be
degree-level qualified in Environmental, Chemical, Marine or Atmospheric Sciences; those with other
numerate degrees (e.g. Physics, Engineering, Mathematics) are also encouraged to apply.

Project Partners:

Plymouth Marine Laboratory (PML) is a world-leading marine research institute with state-of-the-art
facilities and expertise in air-sea exchange research. Central to this PhD are the long-term atmospheric
observatory (Penlee Point in Cornwall and ocean
mooring station ( The University of
Exeter (UoE) was ranked (in REF2014) 4th for Earth Systems and environmental sciences and is a centre for
world-leading interdisciplinary climate change research and modelling. Supervisors on this proposed PhD
work (Yang from PML and Browse from UoE) have collaborated in recent years on projects about the
atmospheric impact of ship exhaust emissions.


The student will receive project specific training in topics such as air-sea exchange, ocean biogeochemistry,
and atmospheric chemistry. The student will also be trained to operate state-of-the-art instrumentation
(PML), perform quantitative data analysis, and develop/code numerical models (UoE). The student will join
an active postgraduate cohort at PML and will also have access to excellent training opportunities in a
range of academic skills including scientific writing, presentation and communication, statistics through the
Doctor Training Programme. The student is further encouraged to attend an intensive, international
summer/winter school in atmospheric chemistry/air-sea exchange. They will gain an understanding of good
laboratory practice, quality assurance, and health and safety procedures within a research laboratory
setting (valuable skills in academic, industry and consultancy careers).

Background reading and references

• Altieri, K. E. et al.: Air-sea ammonia fluxes calculated from high-resolution summertime observations across the
Atlantic Southern Ocean. Geophysical Research Letters, 48, 2021.
• Dunne et al.: Global atmospheric particle formation from CERN CLOUD measurements, Science, 2016.
• Paulot, F. et al: Ocean ammonia outgassing: Modulation by CO2 and anthropogenic nitrogen deposition.
Journal of Advances in Modeling Earth Systems, 12, 2020.
• Pye, H. O. T. et al.: The acidity of atmospheric particles and clouds, Atmos. Chem. Phys., 20, 4809–4888, 2020.

Useful Links:

Prospective applicants: For information about the application process please contact the Admissions team
via Each research studentship project advertisement has an ‘Apply Now’
button linking to an application portal. Please note that applications received via other routes including a
standard programme application route will not be considered for the studentship funding. 


NERC GW4+ DTP studentships are open to UK and Irish nationals who, if successful in their applications, will receive a full studentship including payment of university tuition fees at the home fees rate.

A limited number of full studentships are also available to international students which are defined as EU (excluding Irish nationals), EEA, Swiss and all other non-UK nationals.  For further details please see the NERC GW4+ website.

Those not meeting the nationality and residency requirements to be treated as a ‘home’ student may apply for a limited number of full studentships for international students. Although international students are usually charged a higher tuition fee rate than ‘home’ students, those international students offered a NERC GW4+ Doctoral Training Partnership full studentship starting in 2022 will only be charged the ‘home’ tuition fee rate (which will be covered by the studentship). 

International applicants need to be aware that you will have to cover the cost of your student visa, healthcare surcharge and other costs of moving to the UK to do a PhD. More information on this is available from the universities you are applying to (contact details are provided in the project description that you are interested in.

The conditions for eligibility of home fees status are complex and you will need to seek advice if you have moved to or from the UK (or Republic of Ireland) within the past 3 years or have applied for settled status under the EU Settlement Scheme.


Entry requirements

Applicants should have obtained, or be about to obtain, a First or Upper Second Class UK Honours degree, or the equivalent qualifications gained outside the UK.   Applicants with a Lower Second Class degree will be considered if they also have Master’s degree.  Applicants with a minimum of Upper Second Class degree and significant relevant non-academic experience are encouraged to apply.

All applicants would need to meet our English language requirements by the start of the  project


How to apply

In the application process you will be asked to upload several documents.  Please note our preferred format is PDF, each file named with your surname and the name of the document, eg. “Smith – CV.pdf”, “Smith – Cover Letter.pdf”, “Smith – Transcript.pdf”.

  • CV
  • Letter of application outlining your academic interests, prior research experience and reasons for wishing to undertake the project.
  • Transcript(s) giving full details of subjects studied and grades/marks obtained.  This should be an interim transcript if you are still studying.
  • If you are not a national of a majority English-speaking country you will need to submit evidence of your current proficiency in English, please see the entry requirements for details.
  • Two references

Reference information
You will be asked to submit two references as part of the application process.  If you are not able to upload  your reference documents with your application please ensure you provide details of your referees.  If you provide contact details of referees only, we will not expect receipt of references until after the shortlisting stage. Your referees should not be from the prospective supervisory team.

If you are shortlisted for interview, please ensure that your two academic referees email their references to the, 7 days prior to the interview dates. Please note that we will not be contacting referees to request references, you must arrange for them to be submitted to us by the deadline.

References should be submitted by your referees to us directly in the form of a letter. Referees must email their references to us from their institutional email accounts. We cannot accept references from personal/private email accounts, unless it is a scanned document on institutional headed paper and signed by the referee.

All application documents must be submitted in English. Certified translated copies of academic qualifications must also be provided.

The closing date for applications is 1600 hours GMT Friday 10 January 2022. Interviews will be held between 28 February and 4 March 2022.  For more information about the NERC GW4+ DPT please visit

If you have any general enquiries about the application process please email  Project-specific queries should be directed to the lead supervisor.

Data Sharing
During the application process, the University may need to make certain disclosures of your personal data to third parties to be able to administer your application, carry out interviews and select candidates.  These are not limited to, but may include disclosures to:

  • the selection panel and/or management board or equivalent of the relevant programme, which is likely to include staff from one or more other HEIs;
  • administrative staff at one or more other HEIs participating in the relevant programme.

Such disclosures will always be kept to the minimum amount of personal data required for the specific purpose. Your sensitive personal data (relating to disability and race/ethnicity) will not be disclosed without your explicit consent.


Application deadline:10th January 2022
Value:£15,609 per annum for 2022-23
Duration of award:per year
Contact: PGR Enquiries