High resolution 2D imaging of trace elements in soils by diffusive gradient thin-film (DGT) and laser ablation (LA) ICP-MS

Dr Paul Williams from Queen's University Belfast will be giving a seminar entitled 'High resolution 2D imaging of trace elements in soils by diffusive gradient thin-film (DGT) and laser ablation (LA) ICP-MS' at the James Hutton Institute Aberdeen.

Abstract

Rice contains ~10 times more arsenic than other cereal staples, and is the dominant food source of inorganic arsenic exposure to the world’s population. The anaerobic biogeochemistry of paddy fields makes them vulnerable to excessive arsenic mobilisation and subsequently assimilation by rice. Uptake typically occurs at root apices, sites of rapid entry for water and nutrients, where radial oxygen losses are highest. Therefore, nutrient and toxic metal uptake must largely occur through zones of oxidation and micro-gradients in H⁺concentration. Yet, the precise processes controlling the acquisition of trace elements in rice are difficult to explore experimentally due to a lack of suitable methods.

Using the diffusive gradients in thin films (DGT) gel based dynamic sampling technology, planar optode and laser ablation-ICP-MS as exemplar techniques, this presentation reviews recent advances in chemical imaging and the measurement of arsenic dynamics in rice rhizospheres. The results highlight the need to consider the kinetics of arsenic mobilisation, in situ speciation, as well as the importance of simultaneous/high resolution measurements of multiple analytes, in order to decipher the geochemical processes modulating arsenic remobilisation dispersion and plant uptake.

Biography

Dr Paul Williams is a Lecturer in Soil and Environmental Biogeochemistry at Queen’s University Belfast. Paul obtained his PhD degree in Biological Sciences from the University of Aberdeen in 2007. Previous to working at Queen’s he held Research Fellowships with the Chinese Academy of Sciences, Lancaster University and a Lectureship with the University of Nottingham. 

Paul, an analytical and environmental chemist, has research interests orientated around the role of soils and rhizospheres in global food security. Specific interests and projects focus on the influence of soil dynamic processes and chemical speciation on trace element (both toxic and essential) uptake by plants, visualising rhizosphere micro-heterogeneity through high resolution measurements using DGT and DET techniques, and bettering in situmonitoring of the environment.

Techniques and methods that Paul uses include multi-element chromatography (IC-ICP-MS), laser-based analytical measurement (LA-ICP-MS), passive sampling (DGT, DET), optical sensors (colour ratiometric planar optodes), in-situ UV/vis spectrometry and XRF analysis.

The seminar will be hosted by Dr Luke Beesley.