The first year of my PhD research: iodine geodynamics… by Olivier Humphrey

The shores of Lake Malawi.
Hi, my name is Olivier and I have just started the second year of my PhD at the Centre for Environmental Geochemistry (University of Nottingham and the BGS). My research revolves around iodine geodynamics and plant availability. In this blog I will provide a brief update of some of the work I have been doing over the past year.

Iodine is an essential micronutrient involved in the production of thyroid hormones. Approximately one-third of the world’s population has inadequate iodine intake, and this causes a spectrum of clinical and social issues, collectively known as Iodine Deficiency Disorders (IDD). Dietary supplementation, by means of iodised salt, is commonly used around the world to reduce the prevalence of IDD. However, iodine biofortification represents an area of active research as a cost effective strategy to address global iodine deficiency without the limitations associated with iodised salt. Despite this a much greater understanding of soil-plant uptake is required.

I’ve had a busy year becoming familiar with the extensive literature surrounding iodine geodynamics and plant uptake/availability, working on a review paper and planning/starting various experiments. One of my current experiments includes investigating the uptake mechanisms of iodine in spinach and tomato plants. These are two crops which have been shown to respond well to iodine treatments and have great potential for biofortification programmes. A series of experiments have been designed to investigate the uptake, translocation (from root to foliage and foliage to root) and storage in the mature plants. These experiments will include the use of stable radioactive iodine (I-129), by using multiple isotopes it will be possible to observe potential changes in chemical speciation (conversations between iodide and iodate) as the plant interacts with the iodine. Over the summer I was able to conduct an experiment to investigate where mature spinach and tomato plants predominately store iodine. I have now harvested and prepared the samples; I will perform the ICP-MS analysis very soon.

Peat bogs of Hautes-Fagnes. 
This summer, I attended my first international conference in Brussels for the Society for Environmental Geochemistry and Health’s (SEGH) annual conference, where I presented a poster summarising my PhD research. This was a great opportunity to meet other scientists from around the world with similar interests. We happened to be in Brussels for the Ommegang of Brussels which is an annual religious procession, naturally this involves people fighting on stilts and a huge wooden horse being paraded around Brussels’ Grand Place! On the final day, we went on a field trip to the peat bogs of Hautes-Fagnes, where we were given a talk about how the peat bogs were being used to look at the effects of industry on pollutant levels in the area.

I also participated in a 2 week Africa-UK doctoral training network capacity strengthening exercise. The network, established between the UK, Zambia, Zimbabwe, and Malawi, held their annual meeting in Lilongwe, Malawi this year. After the official opening meeting, which included multiple presentations from our various guests of honour and a brief appearance on national TV, it was time to get to work. The network is aimed at providing sustainable capacity strengthening in soil geochemistry and associated disciplines (see previous blog by Michael Watts). It was great to see all the Royal Society - Department for International Development (RS-DFID) PhD students, local scientists and lab technicians and catch up with their progress again after they visited the UK in May. The first week was based at the Department for Agricultural Research Services in Chitedze for training in soil chemistry, quality assurance and preparation of reference materials via lectures and participatory demonstrations from Dr. Charles Gowing and Dr. Michael Watts (BGS). I was also fortunate enough to visit Lake Malawi following a lecture in the field from Malawi’s leading pedologist Prof. Max Lowole and try some of the Lakes famous Chambo fish after a hot day in the African sunshine. The second week, based at LUANAR: Lilongwe University of Agriculture & Natural Resources, focused on generic training and included statistical analysis, GIS, ethical awareness and presentation skills, the sessions were run by Dr. Murray Lark (BGS), Prof. Amon Murwira (UoZ), Dr. Kate Millar (UoN) and Prof. Martin Broadley (UoN).

Prof. Max Lowole providing a lecture to the research group on a Malawian vertisol. 
Over the next few months I will continue with my plant experiments to identify uptake pathways and investigate translocation mechanisms when iodine is applied to the plants in the form of a foliar spray. These experiments will be based in the growth rooms at Sutton Bonington (UoN) and analysed at BGS, thereby maximising the resources made available to me through the Centre for Environmental Geochemistry, from which my funding originates. I am also planning an innovative soil experiment involving microdialysis probes that I hope to use to extract soil solution and analyse the chemical speciation over a short-term period using size exclusion chromatography (SEC). The use of SEC, coupled to ICP-MS, will enable me to look at different size fractions of iodine, including organically bound iodine. This will provide a much clearer understanding of how iodine behaves in soils shortly after rainfall or fertilization events when iodine is most available for plant uptake. By understanding the dynamic processes that occur during these events it will be possible to understand the factors that limit plant uptake.


The PhD is supervised under the umbrella of the Centre for Environmental Geochemistry:
Dr Scott Young, Dr Liz Bailey and Professor Neil Crout (University of Nottingham) and 
Dr Michael Watts and Dr Louise Ander (BGS)