The Helmholtz Centre Potsdam - GFZ German Research Centre for Geosciences is the national centre for geosphere research. As a member of the Helmholtz Association we are part of the largest German scientific organization. With around 1,300 employees we develop a sound understanding of the systems and processes of the solid Earth as well as strategies and options for action to face global change and its regional impacts, to understand natural hazards and reduce associated risks, and to assess the influence of humans on the Earth's system.

As a partner in Geo.X, the GFZ has access to an excellent network of other geoscience institutions in Potsdam and Berlin. This largest regional concentration of geoscientific competence in Europe offers first-class cooperation and development opportunities.

For section 3.3 Earth Surface Geochemistry (department "Geochemistry"), we are looking for a:

PhD Student (f/m/x) in Isotope Geochemistry Reference Number 4954

The PhD position is part of the DFG-funded project "Towards a new, experimentally-grounded model of the evolution of the boron isotope composition of seawater" (PI Dr. Michael Henehan). Boron isotopes are a vital proxy for reconstructing past CO₂ levels and past periods of rapid climate change. However, beyond a few million years ago, applications of the proxy rely on estimates of the boron isotope composition of seawater, which are a considerable source of uncertainty. This PhD project will address this by revisiting (with new experiments) the grounding principles of global boron cycling – in particular the interaction between boron and secondary minerals (clays). With their new experimental data in hand, the PhD candidate will – together with their supervisory team – construct a new numerical model of how the boron isotopic composition of seawater has evolved over the past 100 million years, potentially greatly improving estimates of past pCO₂. The successful applicant will work within a vibrant, international, diverse and multidisciplinary research group (Section 3.3, Earth Surface Geochemistry) at the GFZ, and will receive training in the methodology of boron and lithium isotope analysis within the Helmholtz Laboratory for the Geochemistry of the Earth Surface, a world-class facility equipped with boron-free clean laboratories and multi-collector and single-collector ICPMS instruments for analysis. Funds are also set aside for attendance at the Urbino Summer School in Paleoclimatology in Italy.

Your responsibilities:

carrying out experiments investigating B and Li isotope fractionation during adsorption on clays
working efficiently and responsibly in a metal-free clean laboratory environment
developing and applying numerical box models in collaboration with your supervisory team
presentation of results at international conferences and in scientific publications

Your qualifications:

a Master's degree (or equivalent) in Geosciences, Chemistry or other related sciences
fluent in spoken and written English
a positive attitude, excellent problem-solving skills and the ability to work well independently and within a team
prior experience in clean laboratory work and/or numerical modelling is beneficial but not essential

Starting date:	1^st July 2021 (with scope for flexibility)
Fixed term:	3 years
Working hours:	part-time 75 % (currently 29.25 h/week)
Salary:	This position has been assessed as being salary group 13 according to "TVöD Bund (Tarifgebiet Ost)". The salary group will be determined by the conditions of the collective wage agreement and the appropriate personal qualifications.
Location:	Potsdam