Rebecca Fraser

Fluorescent imaging of permeable reactive barriers for remediation of radionuclide contaminated groundwater

PhD Research Student

Address:
GPRG
Kroto Research Institute
North Campus, University of Sheffield
Broad Lane
Sheffield
S3 7HQ
United Kingdom

Telephone: +44 (0)114 222 5784
Fax: +44 (0)114 222 5701
Room: G21

email : r.fraser@sheffield.ac.uk

Current Research Interests

This project addresses the remediation of sites that are potentially contaminated with radionuclides such as Uranium and Technetium. Radioactive isotopes of these elements behave as heavy metal contamination in soils and groundwater. Both natural and engineered remediation options include the reductive precipitation of these elements and their associated immobilisation as mineral phases. The aim of this approach to risk reduction is to decrease the concentration and the flux of radioactivity and metals, to receptors that are downstream of source areas such as contaminated land and sub-surface waste repositories. Previous research has shown that iron particles are capable of abiotically reducing mobile uranium (VI) into immobile uranium (IV) through adsorption and precipitation reactions.

Zero-valent iron can be used to act as an effective reductant within sub-surface permeable zones such as engineered reactive barriers to control contaminant plumes, or in reactive containment walls to reduce source strength from a waste repository. Fluorescence imaging can be used to monitor changes in dissolved oxygen, pH variations and reduced species formation such as U(VI) → U(IV). Fluorescent indicators such as Ru(phen)3Cl2 can give a measurement of how much dissolved oxygen is present in a solution under UV light, whilst Pyranine and fluorescein are used to give accurate pH readings over a narrow range and low ionic strengths.