Renforth, P, Mayes, WM, Jarvis, AP, Burke, IT, Manning, DAC and Gruiz, K (2012) Contaminant mobility and carbon sequestration downstream of the Ajka (Hungary) red mud spill: the effects of gypsum dosing. Science of the Total Environment. ISSN 0048-9697 (In Press)Full text available as:
A number of emergency pollution management measures were enacted after the accidental release of caustic bauxite processing residue that occurred in Ajka, western Hungary in October, 2010. These centred on acid and gypsum dosing to reduce pH and minimise mobility of oxyanion contaminants mobile at high pH. This study assesses the effectiveness of gypsum dosing on contaminant mobility and carbon sequestration through assessment of red mud and gypsum-affected fluvial sediments via elemental analysis, sequential extraction and stable isotope analysis. There is a modest uptake of contaminants (notably As, Cr, and Mn) on secondary carbonate-dominated deposits in reaches subjected to gypsum dosing. C and O stable isotope ratios of carbonate precipitates formed as a result of gypsum dosing are used to quantify the importance of the neutralisation process in sequestering atmospheric carbon dioxide. This process is particularly pronounced at sites most affected by gypsum addition, where up to 36% of carbonate-C appears to be derived from atmospheric in-gassing of CO2. The site is discussed as a large scale analogue for potential remedial approaches and carbon sequestration technologies that could be applied to red mud slurries and other hyperalkaline wastes. The results of this work have substantial implications for the aluminium production industry in which 3-4% of the direct CO2 emissions may be offset by carbonate precipitation. Furthermore, carbonation by gypsum addition may be important for contaminant remediation, also providing a physical stabilisation strategy for the numerous historic stockpiles of red mud.
|Copyright, Publisher and Additional Information:||© 2012 Elsevier. This is an author produced version of a paper accepted for publication in Science of the Total Environment. Uploaded in accordance with the publisher's self-archiving policy|
|Academic Units:||The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds)|
|Depositing User:||Symplectic Publications|
|Date Deposited:||30 Jan 2012 12:43|
|Last Modified:||08 Feb 2013 17:36|
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