The effect of EDTA on the groundwater transport of thorium through sand.

The effect of the anthropogenic complexing agent EDTA on thorium transport in groundwater has been studied using sand-packed columns and flow rates in the range of 20-100 m y⁻¹. The concentrations injected into the columns were in the range of 0.4-4 mM for Th and 4-40 mM for EDTA, and with EDTA:Th ratios in the range 1:1 to 10:1.

Characterisation of thorium-ethylenediaminetetraacetic acid and thorium-nitrilotriacetic acid species by electrospray ionisation-mass spectrometry.

Electrospray ionisation-mass spectrometry (ESI-MS) has been used to investigate the speciation of Th in the presence of two common organic complexing agents found in radioactive wastes, EDTA and NTA. These ligands may enhance radionuclide migration from nuclear wastes and contaminated land, and characterisation of the complexes formed will improve our understanding of their environmental mobility. When acetic acid and ammonia were used to adjust the pH, the dominant Th-EDTA species changed from the mixed ligand [ThEDTAac](-) complex to [ThEDTAOH](-) and [ThEDTA(OH)(2)ac](3-) as the pH increased, with all species co-existing, to some extent, over the pH range (2.