Two PhD positions on methane and ammonium dynamics in marine systems (1.0 FTE, 4 years)

Hours per week: 
36 to 40
Faculty of Geosciences
GEO / Dept AW
Application deadline: 

Job description

The Department of Earth Sciences at Utrecht University, Utrecht, and the Department of Microbiology at Radboud University, Nijmegen, in the Netherlands have an opening for two fully funded PhD projects to work on the ERC Synergy project MARIX for 4 years. MARIX stands for 'Methane and Ammonium Removal In redoX transition zones'. The project focuses on the discovery of new microbial and geochemical pathways of removal of methane and ammonium in sediments and the water column of coastal marine systems.

Sharp redox transitions in marine environments are prime sites for removal of toxic ammonium and the greenhouse gas methane. In this project, we are exploring the redox reactions, microbial players and key controls that explain this removal.

The MARIX project combines sea-based fieldwork with laboratory experiments and reactive transport modelling. The two new PhD candidates will focus on sediment processes in a range of field work areas including the Netherlands and Sweden. A key goal will be to increase the understanding of processes leading to the anaerobic removal of methane and ammonium coupled to reduction of iron oxides and the interactions between the nitrogen, methane and iron cycles.

The MARIX team and collaborating research groups currently consists of Prof C.P. Slomp (UU Geochemistry), Prof M.S.M. Jetten (RU Microbiology), several PhD students and Postdocs and complementary staff members at Utrecht and Radboud Universities. PhD1, with a focus on geochemistry, will be based in the Geochemistry group at Utrecht University. PhD2, with a focus on microbiolology, will be based in the Microbiology group at Radboud University.

A personalised training programme will be set up, mutually agreed on recruitment, which will reflect the candidate's training needs and career objectives. As part of this training, up to 10% of the candidate's time will be dedicated to assisting in Bachelor's and Master's teaching programmes.


For the Geochemistry position, we are seeking a PhD candidate with an MSc degree in earth sciences, environmental sciences or an equivalent degree with demonstrable affinity with (inorganic) geochemistry. Experience in quantitative modeling is helpful, but not a requirement.

For the Microbiology position, we are seeking a PhD candidate with an MSc degree in microbiology or biotechnology. Experience in molecular analysis and bioreactor experiments is helpful, but not a requirement.

Candidates should be interested in performing fundamental, interdisciplinary research in an applied context. We are looking for excellent team players as this project requires close collaboration within the MARIX team and with external (inter)national researchers. Excellent written and spoken English skills are essential.


We offer a temporary position (1.0 FTE), initially for one year with an extension to four years in total upon a successful assessment in the first year, and with the specific intent that it results in a doctorate within this period. The gross salary ranges between €2,395 in the first year and €3,061 in the fourth year (scale P according to the Collective Labour Agreement Dutch Universities) per month for a full-time employment.

Salaries are supplemented with a holiday bonus of 8% and a year-end bonus of 8.3% per year. In addition, both Utrecht University and Radboud University offer excellent secondary conditions, including an attractive retirement scheme, (partly paid) parental leave, the choice for a good balance between work and private (a good arrangement for leave, among other things), possibilities for development and flexible employment conditions (multiple choice model). More information about working at Utrecht University and Radboud University can be found at: Utrecht and Nijmegen.

About the organisation

Utrecht University
A better future for everyone. This ambition motivates our scientists in executing their leading research and inspiring teaching. At Utrecht University, the various disciplines collaborate intensively towards major societal themes. Our focus is on Dynamics of Youth, Institutions for Open Societies, Life Sciences and Sustainability.

The Faculty of Geosciences studies the Earth: from the Earth's core to its surface, including the spatial and material utilisation of the Earth by humans - always with a focus on sustainability and innovation. With 3,400 students (BSc and MSc) and 720 staff, the faculty is a strong and challenging organisation. The Faculty of Geosciences is organised in four Departments: Earth Sciences, Human Geography & Spatial Planning, Physical Geography, and Sustainable Development.

The Department of Earth Sciences conducts research and teaching across the full range of the solid Earth and environmental earth sciences, with activities in almost all areas of geology, geochemistry, geophysics, biogeology and hydrogeology. The department hosts an international tenured staff of over 45 scientists and more than 110 PhD candidates and Postdoctoral Researchers. Our research programme spans four intertwined themes: Climate & Life, Earth interior, Earth materials, and Environmental Earth Sciences. We house or have access to a wide variety of world-class laboratories. The Geochemistry Group focuses on the geochemistry of the earth surface, combining field data with experimental, modeling and theoretical approaches to elucidate biogeochemical cycles and mineral transformations along the aquatic continuum, e.g. from weathering of rocks to the biogeochemistry of deep sea sediments. Biogeochemical processes are investigated from the nanometer to the global scale and the geological record is utilised to better project earth surface conditions in the future. We are part of the excellence (Gravitation) centre in climate research (NESSC).

Radboud University

We want to get the best out of science, others and ourselves. Why? Because this is what the world around us desperately needs. Leading research and education make an indispensable contribution to a healthy, free world with equal opportunities for all. This is what unites the more than 22,000 students and 5,000 employees at Radboud University. And this requires even more talent, collaboration and lifelong learning. You have a part to play!

The Faculty of Science is a student-oriented faculty with a strong research base. The faculty aims to be an academic community with international prominence and engages students actively in that community. Through high quality teaching, the Faculty of Science Lecturers are dedicated to challenge students to become critical academics and responsible decision-makers, willing and able to take up influential positions in our increasingly international society.

The main focus of the Microbiology Cluster at the Institute for Water and Wetland Research (IWWR) is on discovering and understanding new anaerobic microbes in the methane and nitrogen cycles using state-of-the-art microbial, physiological, bioreactor, biochemical, molecular, multi-omics and microscopic methods. We are part of the excellence (Gravitation) centres in anaerobic microbiology (SIAM) and climate research (NESSC).

Additional information

For more information about these positions, please contact: 
for the geochemistry position: Prof Caroline Slomp (Professor of Biogeochemistry), via, and for the microbiology position: Prof Mike Jetten (Professor of Microbiology), via


To apply, please send your curriculum vitae, including a letter of motivation via the ‘apply’ button below. Please indicate in your application which position you are applying for.

The application deadline is April 19th, 2021. Evaluations and interviews are planned soon thereafter. We seek to initiate the position no later than September 1st, 2021. Online screening may be part of the selection.

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The application deadline is 19 April 2021.