Stable Isotope Research Apprenticeship / / by Savannah Worne

After completing a PhD researching the interaction between subarctic sea ice, oceanic nutrient upwelling and global climate over the last 1 million years at the University of Nottingham, Savannah Worne is now undertaking an apprenticeship with us here at the British Geological Survey. Here, she tells us a little bit more about what the role entails...

Samples in glass jugs being prepared.
Preparing samples

Hi, I’m Savannah Worne and I have just started a one year postgraduate Stable Isotope Research Apprenticeship in Keyworth, based in the geochemistry department. My key responsibilities will be preparing and analysing a range of samples for organic carbon and nitrogen isotopes (using the new Elementar precision mass spectrometer). I also hope to get involved in a whole range of light stable isotope analysis as the opportunity arises, for example analysing biogenic silica for oxygen and carbon isotopes.

Prior to this internship, I was a PhD student at the University of Nottingham, where my thesis research centred on creating a high resolution reconstruction of sea ice, nutrient cycling and ocean-atmosphere CO2 dynamics in the Bering Sea over the last one million years, using geochemical and micropalaeontological records from a deep-ocean sediment core taken by the Integrated Ocean Drilling Program (IODP). During this time, I completed some of my own sample preparation and analysis at BGS and so I was thrilled by the opportunity to come back and gain further technical experience in stable isotope analysis, using brand new equipment.

So far, I have undergone in-depth training on how to correctly and safely run, dismantle and replace parts for both the elemental analyser and mass spectrometer, including how to operate the respective software and extract and process data from them. While the elemental analyser quantifies the organic carbon and nitrogen content of sample, the mass spectrometer analyses the stable isotope composition. Alongside my mentor Dr Jack Lacey, we have undertaken rigorous calibration and quality assurance checks for the elemental analyser, ensuring that we can accurately and precisely reproduce the organic nitrogen and carbon content of international standards and to ensure the new instrument is functioning consistently. Since then, I have now started to analyse real samples for a range of projects as part of the National Environmental Isotope Facility (a NERC Service and Facility operated out of BGS). As I had only previously been a stable isotope data user, it has been fascinating to see how much work goes on behind the scenes to ensure the data is accurate, reliable and repeatable. 

Picture of Savannah at work in front of her computer, with scientific machinery next to her
Savannah in one of the geochemistry labs

Aside from this, I have been busy re-familiarising myself with sample preparation techniques, particularly for organic carbon analysis, including freeze-drying samples, decarbonating through acid digestion, sample homogenisation through grinding and weighing out samples to the microgram level. I have also been given an introduction to biogenic silica analysis for oxygen and silicon isotope analysis. I am excited to be involved with a large range of work completed by BGS, and am looking forward to continuing to learn and grow within my role for the rest of my year with the team.