Wednesday, 26 October 2016

Getting a Read on Radon: measurement of radon activity in groundwater samples from a proposed fracking site - a student project! James Dinsley

My name is James Dinsley, an Environmental Science student from the University of Nottingham and I am currently a quarter of the way through a one-year placement with the British Geological Survey, working in the Inorganic Geochemistry Laboratories in Keyworth, Nottingham. Over my year with the BGS, I have been supporting projects with Dr Charles Gowing and Dr Andy Marriott looking at the development and validation of (i) a method for determining the amount of radon in groundwater and its application to environmental baseline monitoring at proposed shale gas exploration sites, and (ii) a method of using a form of radioactive lead (210Pb) to determine the age of lake sediments. I will also be working in the aqueous chemistry laboratories, where I will use different chemical tests to analyse the composition of water samples for clients. As part of my work, I have learned how to conduct key laboratory tests such as determining soil pH and organic matter content, water pH and alkalinity, electrical conductivity and total organic carbon.

What does radon have to do with shale gas and fracking?

Fracking is a controversial topic due to public concern about it’s potential environmental and health risks. The process of fracking creates micro-fractures in the target shale rock to release natural gas (methane) for energy supply. One area of concern with fracking and the shale-gas development more generally is the possible release of naturally occurring radioactive materials (NORMs) contained in the shale, e.g. radon (222Rn), a known carcinogen, either as a gas or dissolved in the produced water that also comes up the shale gas well. Human exposure to radon is known to present a health risk if it is not adequately controlled.

In order to understand the potential additional risks that might arise from shale gas operations, a clearer understanding of the baseline groundwater chemistry is needed in areas around proposed development sites.

What have we found so far?

Libby preparing the samples for analysis to
determine radon concentration. 
Charles, Andy and Libby Gallanaugh, the previous placement student from the University of Surrey, refined a method for looking at the emission of alpha particles (a type of radiation) from the radioactive decay of radium (226Ra) in order to quantify the amount of radon present in groundwater samples. To do this, organic chemicals called ‘scintillators’ are used to convert the energy generated by alpha particle emission into light, which is then measured by a detector. More light pulses will indicate a higher amount of radon in the samples.
Libby’s work has identified the most suitable scintillator type and an appropriate scintillator/sample ratio to use, alongside helping to determine the most efficient analytical run time needed. Her results have helped to enhance both the counting efficiency of the detector and improve the quality of the results. It is hoped that the technique that Charles, Andy and Libby were working on could be used directly in the field to reduce the length of time that radium has to decay before analysis.

What are the next steps?

Alongside my duties in the aqueous lab, I will continue to further this research by investigating both the influence of sample temperature on the detector’s ability to quantify the radon concentration; and the influence that major ions in water (e.g. chloride, bicarbonate, etc.) can have on the detector’s readings, since water collected from different environments and rock types will have different chemical compositions! This work will help to ensure that the quantification of radon from field samples are more accurately represented despite variation in where and when sampling takes place.

During my time with the BGS I will also be working on another project, looking at refining a method for using a radioactive lead isotope (210Pb) to determine the age of Malaysian lake sediments. Ageing these sediments will help to reconstruct past pollution events from possible human activities. 210Pb dating can show us changes in sediment deposition over time, which is key as this can lead to changes in the lake’s physical and chemical characteristics. By using data collected from 210Pb dating, decision makers will then be able to determine the best method to remediate contaminated lakes. This project is being run in collaboration with the University of Nottingham through the joint Centre for Environmental Geochemistry.

I am enjoying my time with the BGS so far, and I am looking forward to getting involved with learning and experiencing as much as possible, alongside having the opportunity to meet many more people!

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