Prolonged testing of metal mobility in mining-impacted soils amended with phosphate fertilisers

Munksgaard, Niels C., Lottermoser, Bernd G., and Blake, Kevin (2012) Prolonged testing of metal mobility in mining-impacted soils amended with phosphate fertilisers. Water, Air and Soil Pollution, 223 (5). pp. 2237-2255.

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The aim of the study was to determine whether the application of superphosphate fertiliser to soils contaminated with mine wastes can inhibit metal and metalloid mobility (Cu, Pb, Zn, Cd, Fe, Mn, As, Sb) in the long term. Contaminated soils contained sulfide- and sulfate-rich waste materials from the Broken Hill and Mt Isa mining centres. Results of long-term (10 months) column experiments demonstrate that fertiliser amendment had highly variable effects on the degree of metal and metalloid mobilisation and capture. Rapid release of metals from a sulfate-rich soil showed that phosphate amendment was ineffective in stabilising highly soluble metal-bearing phases. In a sulfide-rich soil with abundant organic matter, complexing of metals with soluble organic acids led to pronounced metal (mainly Cd, Cu and Zn) release from fertiliser-amended soils. The abundance of pyrite, as well as the addition of fertiliser, caused persistent acid production over time, which prevented the formation of insoluble metal phosphate phases and instead fostered an increased mobility of both metals and metalloids (As, Cd, Cu, Sb, Zn). By contrast, fertiliser application to a sulfide-rich soil with low organic carbon content and a sufficient acid buffering capacity to maintain near-neutral pH resulted in the immobilisation of Pb in the form of newly precipitated Pb phosphate phases. Thus, phosphate stabilisation was ineffective in suppressing metal and metalloid mobility from soils that were rich in organic matter, contained abundant pyrite and had a low acid buffering capacity. Phosphate stabilisation appears to be more effective for the in situ treatment of sulfide-rich soils that are distinctly enriched in Pb and contain insignificant concentrations of organic matter and other metals and metalloids.

Item ID: 20895
Item Type: Article (Research - C1)
ISSN: 1573-2932
Keywords: mine waste, metals, fertiliser, immobilisation, remediation
Date Deposited: 13 Mar 2012 06:06
FoR Codes: 05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050207 Environmental Rehabilitation (excl Bioremediation) @ 50%
05 ENVIRONMENTAL SCIENCES > 0503 Soil Sciences > 050304 Soil Chemistry (excl Carbon Sequestration Science) @ 50%
SEO Codes: 96 ENVIRONMENT > 9612 Rehabilitation of Degraded Environments > 961205 Rehabilitation of Degraded Mining Environments @ 100%
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