
%0 Journal Article
%A Thayalakumaran, T. 
%A Vogeler, I. 
%A Scotter, D. R. 
%A Percival, H. J. 
%A Robinson, B. H. 
%A Clothier, B. E. 
%T Leaching of copper from contaminated soil following the application of EDTA. I. Repacked soil experiments and a model
%J Soil Research
%D 2003/04/08
%V 41
%N 2
%P 323-333
%K iron, convection&#8211;dispersion equation, heavy metals.
%R https://doi.org/10.1071/SR02059
%U https://www.publish.csiro.au/paper/SR02059 
%X The EDTA-enhanced remediation of copper contaminated sandy-loam soil of volcanic origin was investigated. The soil, from an orchard, was contaminated with about 250 mg/kg of copper due to the extensive use of copper sprays. Copper-contaminated soil was packed into 100-mm-long columns, and solutions of Na2H2EDTA with CaCl2, raised to a pH of 6.2, were applied at a flow rate of 24 mm/h. Application of an excess of 0.01 M EDTA leached about half the acid-extractable copper from the soil; most of it coming out in the first 3 liquid-filled pore volumes (PV). Also a 0.5 PV pulse of 0.001 M EDTA was applied to similar soil columns and then either leached immediately with 0.005 M CaCl2, or left for periods of up to 1 month before leaching. With immediate leaching, 70% of the EDTA applied was complexed with copper in the leachate, but after a month&#39;s delay only 24% was complexed with copper in the leachate, the rest being complexed with iron. There was no evidence of EDTA retardation or adsorption. The experimental results were simulated using the convection&#8211;dispersion equation, incorporating a source/sink term. This described the competing time-dependent reactions of copper and iron with EDTA, and the reversion of CuEDTA2&#8211; to adsorbed Cu2+ and Fe(III)EDTA&#8211; in solution. Reasonable simulations were achieved, mostly within errors of observation. 
