Use of bone meal amendments to immobilise Pb, Zn and Cd in soil: A leaching column study.
The aim of this study is to test the stabilisation of metals in contaminated soils via the formation of low-solubility metal phosphates. Bone apatite, in the form of commercially available bone meal, was tested as a phosphate source on a mine waste contaminated made-ground with high levels of Pb, Zn and Cd. Triplicate leaching columns were set up at bone meal to soil ratios of 1:25 and 1:10, in addition to unamended controls, and were run for 18 months. The columns were irrigated daily with a synthetic rain solution at pH of 2, 3, and 4.4. After 100 days, the leachate Pb, Zn and Cd concentrations of all amended columns were significantly reduced. For 1:10 treatments, release of these metals was suppressed throughout the trial. For 1:25 treatments, Zn and Cd concentrations in the leachates began to increase after 300 days. DTPA and water extractions showed that Pb and Cd were more strongly held in the amended soils. This study concludes that the complexity of soil processes and the small quantities of metals sequestered precluded determination of a metal immobilisation mechanism.
Sneddon
I R
IR
Department of Mineralogy, The Natural History Museum, Cromwell Road, London SW7 5BD, UK.
Orueetxebarria
M
M
Hodson
M E
ME
Schofield
P F
PF
Valsami-Jones
E
E
D000327:Adsorption; D000818:Animals; D001673:Biodegradation, Environmental; D001688:Biological Products; D002104:Cadmium; D006863:Hydrogen-Ion Concentration; D007220:Industrial Waste; D007854:Lead; D019216:Metals, Heavy; D008903:Minerals; D008906:Mining; D012989:Soil Pollutants; D014961:X-Ray Diffraction; D015032:Zinc
D001688:Biological Products; D007220:Industrial Waste; D019216:Metals, Heavy; D008903:Minerals; D012989:Soil Pollutants; D002104:Cadmium; D007854:Lead; D015032:Zinc; C027762:bone meal