Looking into things… using GeoPET

Author: Stefan Schymura, from Helmholtz-Zentrum Dresden-Rossendorf | HZDR

Researchers wanting to investigate the fate of contaminants in the environment face one challenge: most of nature is opaque. Be it soil, rock formations or organisms, looking inside them to locate small amounts of contaminants is often not possible without basically destroying the sample in question by cutting it up at the end of an experiment. Here it is that Positron Emission Tomography (PET) can help by providing the ability of a non-destructive, four-dimensional visualization of tracer distributions.

Using the special properties of certain radioactive atoms called positron emitters it is possible to track and visualize the distribution of these atoms inside an opaque sample and its change over time. For example, this is used in medicine for the diagnosis of tumors, by visualizing the tumor and its potential remission upon treatment, or diagnosing early stage Alzheimer’s disease, by giving information about the amount of certain receptors in the patient’s brain. At the HZDR Research Site Leipzig, PET is also used to visualize flow in geological material in the context of nuclear waste repository research, thus named GeoPET. Using this technique, the HZDR researchers look, among others, at fluid flow through rock fractures, contaminant transport in porous geological substrates, tightness of technical barriers, leaching of valuable metals or transport of dust in reactor setups.

The technique delivers valuable data about contaminant mobility in the environment

The realisation of such an experiment is the end-point of a long scientific route that involves the production of the name-sake positron* emitters (e.g. F-18, Cu-64, Y-86, etc.) at the in-house cyclotron particle accelerator, the labelling of the contaminant under investigation (e.g. nanoparticles, ionic solutions, biological signalling molecules, water) and the preparation of the geological sample. When performed the experiment delivers valuable data about contaminant mobility in the environment and helps to understand transport processes in nature, thereby contributing to minimising risks towards society and environment.

Within Surfbio, GeoPET allows the tracking of suitably radiolabeled nano/biocolloids and the investigation of the environmental mobility of contaminants such as manufactured nanoparticles in interaction with biofilms.

References:

Kulenkampff et al. (2018): Time-lapse 3D imaging by positron emission tomography of Cu mobilized in a soil column by the herbicide MCPA, Scientific Reports 8, 7091, DOI: 10.1038/s41598-018-25413-9

Kulenkampff et al. (2016): Quantitative experimental monitoring of molecular diffusion in clay with positron emission tomography, Solid Earth, 7, 1207–1215, DOI: 10.5194/se-7-1207-2016

Kulenkampff et al. (2016): Geoscientific process monitoring with positron emission tomography (GeoPET), Solid Earth, 7, 1217–1231, DOI: 10.5194/se-7-1217-2016