Monday, 27 August 2018

Another One Bites The Dust: Dust-to-crop chromium transfer in Zambia – A student project...by Sophia Dowell

Sophia in the lab
Hi my name is Sophia Dowell, I’m an undergraduate chemistry student from the University of Surrey.  I have been working at the British Geological Survey for just over a year, joining the Inorganic Geochemistry team in Keyworth, Nottinghamshire as an industrial placement student in July 2017. The majority of my work whilst here has been focused around the operation of the Agilent 8900 triple quadrupole Inductively Coupled Plasma Mass Spectrometry (ICP-MS) under the supervision of Elliott Hamilton. ICP-MS is used for simultaneous multi element analysis, on a wide variety of sample matrix's from ground waters through to urines and bloods. I have been working on this instrument independently since March, and now have a much better understanding of both the operation and principles. As part of my work, I have also learned how to conduct key laboratory tests, such as determining soil pH and the Unified Barge Method (UBM) analysis for looking at elemental bioaccessibility. Now that my year is coming to an end at the BGS, I have started to train Nicholas Porter who is also a University of Surrey, industrial placement student. I am training Nicholas the basics and passing on my knowledge, so that he can continue my work within the ICP-MS laboratories.

Alongside my work within the lab, I undertook a short research project looking at dust-to-crop transfer of chromium in Zambia. This links directly with Elliott’s PhD work and follows on from both Emily Leader and Lee Evans who were past placement students from the University of Surrey. Chromium (Cr) exists naturally in the environment as both trivalent (Cr (III)) and hexavalent (Cr (VI)) forms. Trivalent chromium is essential for animal well-being and is considered to be vital for insulin regulation and glucose metabolism inside the body. On the other hand hexavalent chromium is classified as a Group A human carcinogen with the respiratory tract being the main target organ for Cr(VI) following inhalation. Although chromium can enter the environment through natural processes the origin of Cr(VI) in the environment is largely anthropogenic.

SEM images with dust on the washed pumpkin leaves
The study used dusts created from the Zambian soils Elliott collected whilst on fieldwork (Elliott Hamilton’s blog) in a glasshouse study at the University of Nottingham’s Sutton Bonington campus. Pumpkin leaves were grown over a period of 3 weeks before the Zambian dust was applied to the leaves. After 4 days the leaves were harvested and brought back to BGS for analysis. The leaves were digested and analysed using ICP-MS and it was found that the chromium concentration in the leaves exposed to the dusts was elevated in comparison to the control leaves. It was later determined, with the help of Dr Lorraine Field, that this increased concentration in washed leaves was likely due to dust particles adhering to the leaf surfaces, rather than through absorption as shown by  scanning electron microscopy (SEM). The SEM images show dust on the washed leaves which was not visible to the human eye.

After I have completed my placement, I will be returning to the University of Surrey for the final year of my undergraduate chemistry degree. I hope to continue into a career in environmental chemistry research after my degree, pursuing a MSc in analytical chemistry or geochemistry. I have loved my time at BGS and in the Inorganic Geochemistry team and believe that the placement has helped me not only develop new laboratory skills that will make me more employable as a graduate, but it has also given me many positive memories of my time here!

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