My role as a stable isotope research assistant

I recently began my role as a stable isotope research assistant at the National Environmental Isotope Facility (NEIF) at BGS’s headquarters in Keyworth, Nottingham.

Prior to working at BGS, I studied for a PhD at Imperial College London. My thesis focused on the zinc and cadmium stable isotope compositions of igneous rocks and meteorites to better understand how Earth obtained volatile elements and species such as water. Whilst studying for my PhD, I gained valuable knowledge, experience and understanding of different isotope systems and mass spectrometry, as well as sample preparation and laboratory techniques. These all helped me hit the ground running when I started my new role at BGS.

My first few months have mainly involved analysing the carbon and oxygen stable isotope compositions of various carbonate samples, for example from lake sediments, as part of the environmental change, adaptation and resilience challenge area. This gives useful insight into how the environment in which these sediments were deposited changed over time, allowing scientists to better understand the processes affecting similar environmental systems today.

Preparation of these sediments usually involves treatment with a dilute bleach solution overnight to remove unwanted organic material that may interfere with the isotope analysis. Each sample is then rinsed through with clean water before being crushed into a fine powder and weighed precisely. Learning these new techniques has given me new skills in the preparation of organic samples through acid digestion and freeze-drying.

A lot of my time at BGS so far has been spent using the carbonate line, a series of glass tubes and valves used to pump out air from bespoke sample vials to keep them under vacuum. This improves the accuracy of the isotope measurements by reducing any interference from unwanted atmospheric gases during analysis. Once under vacuum, each carbonate sample is reacted with phosphoric acid to produce carbon dioxide (CO₂) gas, which is then extracted using the carbonate line. This has given me my first experience in using liquid nitrogen in the laboratory.

I recently began independently analysing the isotope compositions of these samples using a newly acquired gas source mass spectrometer, with the help of Dr Jack Lacey. Jack and I have also spent time carrying out test runs on the instrument to check that it is operating at an acceptable level of accuracy and precision. Additionally, we’ve been carrying out experiments to identify the optimal technique for analysing the oxygen isotope composition of sediments containing low concentrations of siderite, which is an iron carbonate mineral. With time, I hope to gain further experience using additional isotope systems and techniques.

I have thoroughly enjoyed my time spent in the laboratory and learning these new techniques, as well as collaborating with people from both BGS and other institutions. I’m looking forward to developing my skills further over the coming year. Outside of the laboratory, I have also taken part in some BGS Wilding Group events, helping to plant trees and build insect hotels, with the aim of increasing biodiversity here at the Keyworth site.

Author

Dr Harvey Pickard

Plasma mass spectrometry technician

BGS Keyworth

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