My Work Experience Week in the Stable Isotope Facility at the British Geological Survey...by Liam Curtis



Liam and Grace in the Stable Isotope Facility.

Hi, my name is Liam Curtis and I am a 6th form student at Rushcliffe School and I have just finished a week of work experience placement at the British Geological Survey (BGS).  BGS is a world leading geoscience facility in Nottingham; it has facilities ranging from bore drilling to 3D visualisation and everything in-between. I spent this week with another student, Grace who is also writing a blog...

 

I am particularly interested in geochemistry so was thrilled to find out I was going to be working in the Stable Isotope Facility, one of the best laboratories who work on isotopes in the UK! This facility measures the levels of different isotopes of various elements (e.g. carbon, oxygen, silicon) from samples of soils, minerals and rocks and uses this information to deduce what the climate and environment was like on Earth from millions to hundreds of years ago.

The first thing we did after the mandatory health and safety and lab tour, was vacuum extraction of water from soil samples. This involved using liquid nitrogen (at –190^oC!) and a very high vacuum to evaporate then capture all the water from the sample. After collection the water was to be analysed elsewhere (more on that later). This was really interesting physics and chemistry, it was very practical and visual as I could see the ice forming in the tube as it was sucked out of the soil.

Next we started a three day long experiment analysing the different isotopes in some carbonate (its like limestone) samples from a loch in Scotland. This process was extremely useful and interesting as we both got to see and do an actual experiment from start to finish. For me this helped to both further my understanding of chemistry but also got me thinking about my future career as a scientist (maybe a geologist!). The first thing we did was prepare the samples, this involved adding very small amounts of the samples into phosphoric acid and removing all the air so any CO₂ produced would not be contaminated by the CO₂ in the air. As the carbonate reacted we collected the CO₂ gas using liquid nitrogen (very useful stuff as CO₂ condenses at these very low temperatures meaning we can move the CO₂ around as a solid). We then analysed the CO₂ using a very expensive instrument called a mass spectrometer. After we got the data, we analysed the results, coming to the conclusion that sea levels had risen over a period of 7,000 years starting 18,000 years ago as isotopes in the loch where closer to that of marine water to that of fresh water. It’s amazing that isotopes can tell us so much about the Earth.

Liam getting to grips with vacuum extraction
techniques - physics and chemistry!

We also did some water isotope analysis (from the soil water extraction work we did). This started with pipetting 200 microlitres (a tiny drop) of water into vials to be analysed on the mass spectrometer. However it was not that simple, unfortunately mass spectrometers can only analyse gases. This meant that a workaround was needed. To do this the air in the tubes was replaced with CO₂, and then the water and CO₂ mixed, this caused the oxygen in the water to exchange with that in the gas, it was then this gas that was analysed. All very clever stuff!

We also had a go at filtering sediments that where being cleaned in bleach (to remove organic material). These samples had tiny, tiny shells mixed within the sand, these shells needed to be cleaned (in the bleach) then extracted and analysed. So it was down to us to filter them. Fortunately we had plenty of fine sieves and it was exciting to see shells emerge from the dirt.

The whole week has been interesting and useful, even the washing up. I now know what lab work is like and I have had a glimpse into geochemistry. This has made me more interested in the inorganic side to chemistry and allowed to see chemists in action. I am extremely grateful to all the people (Carol Arrowsmith, Chris Kendrick, Melanie Leng, Andi Smith and Jack Lacey) that gave up there time to help me and showing me around. It has been a fantastic week and really educational.

Liam Curtis is a 6th form student at Rushcliffe School