Assessment of Technosol formation and in situ remediation in capped alkaline tailings

Santini, Talitha C. and Fey, Martin V. (2015) Assessment of Technosol formation and in situ remediation in capped alkaline tailings. Catena, 136 17-29. doi:10.1016/j.catena.2015.08.006

Author Santini, Talitha C.
Fey, Martin V.
Title Assessment of Technosol formation and in situ remediation in capped alkaline tailings
Journal name Catena   Check publisher's open access policy
ISSN 0341-8162
Publication date 2015-09-01
Year available 2015
Sub-type Article (original research)
DOI 10.1016/j.catena.2015.08.006
Open Access Status Not Open Access
Volume 136
Start page 17
End page 29
Total pages 13
Place of publication Amsterdam, Netherlands
Publisher Elsevier
Collection year 2016
Language eng
Formatted abstract
Technosols formed from mineral processing wastes such as tailings are of growing importance worldwide due to the increasing demand for mineral and energy resources. The construction and nature of tailings and capping materials in tailing storage facilities are likely to influence soil formation rates; however, these have not been evaluated to date. This study used bauxite residue (alumina refining tailings) as a model material to compare soil development and in situ remediation with reference to initial residue composition, landscape position, and cap type. Soil development in the capped tailings deposits was limited to accumulation of organic matter in the upper 0–2 cm of capping materials, and shallow (< 10 cm deep) decreases in pH and salinity within the underlying tailing layers. Landscape position had little effect on soil development due to the formation of technic hard material through calcite cementation in sintered bauxite residues, which inhibited weathering. Weak structure development, likely due to volume shrinkage through desiccation, was observed in unsintered bauxite residue. Leaching of acidic pore waters from pyritic mine spoil caps aided in pH neutralization in unsintered bauxite residues.

The current Technosol classification was adequate for description of the soil materials within the study site; however, the introduction of a novel prefix qualifier, Ordic, would enable more accurate description of multilayered Technosols. Unsintered bauxite residue under a pyritic mine spoil cap was predicted to move from a Spolic Technosol to a Haplic Cambisol based on variations in structure and colour within the capping. The lack of observable weathering precluded identification of a likely pedogenic trajectory in sintered bauxite residue. Accelerating natural processes of soil development and in situ remediation may be achieved by application of chemically reactive caps; however, these should not preclude atmospheric gas exchange, leaching, or interaction with biota as pedogenesis will be retarded.
Keyword Pedogenesis
Tailings management
Bauxite residue
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

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