Pedosphere 22(4): 544--553, 2012
ISSN 1002-0160/CN 32-1315/P
©2012 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| Attenuation of metal bioavailability in acidic multi-metal contaminated soil treated with fly ash and steel slag |
QIU Hao1, GU Hai-Hong1, HE Er-Kai1, WANG Shi-Zhong1 and QIU Rong-Liang1,2 |
1 School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275 (China);
2 Guangdong Provincial Key Lab of Environmental Pollution Control and Remediation Technology, Guangzhou 510275 (China) |
| ABSTRACT |
| A pot experiment was conducted with multi-metal (Pb, Cd, Cu, and Zn) contaminated acidic soil to investigate changes in available metal burden resulting from the application of industrial wastes (fly ash and steel slag). The efficiency of amendments-induced metal stabilization was evaluated by diffusive gradients in thin films (DGT), sequential extraction, and plant uptake. The stability of remediation was assessed by an acidification test and by chemical equilibrium modeling. Addition of fly ash (20 g kg-1)and steel slag (3 g kg-1)resulted in similar increase in soil pH. Both amendments significantly decreased the concentrations of metals measured with DGT (CDGT) and the metal uptake by Oryza sativa L. Significant correlations were found between CDGT and the concentration of a combination of metal fractions (exchangeable, bound to carbonates, and bound to Fe/Mn oxides), unraveling the labile species that participate in the flux of metal resupply. The capability of metal resupply, as reflected by the R (ratio of CDGT to pore water metal concentration) values, significantly decreased in the amended soils. The CDGT correlated well with the plant uptake, suggesting that DGT is a good indicator for bioavailability. Acidification raised the extractable metal concentration in amended soil but the concentration did not return to the pre-amendment level. Equilibrium modeling indicated that the soil amendments induced the precipitation of several Fe, Al and Ca minerals, which may play a positive role in metal stabilization. Chemical stabilization with alkaline amendments could be an effective and stable soil remediation strategy for attenuating metal bioavailability and reducing plant metal uptake. |
| Key Words: acidification, chemical stabilization, diffusive gradients in thin films (DGT), heavy metal, remediation |
| Citation: Qiu, H., Gu, H. H., He, E. K., Wang, S. Z. and Qiu, R. L. 2012. Attenuation of metal bioavailability in acidic multi-metal contaminated soil treated with fly ash and steel slag. Pedosphere. 22(4): 544-553. |
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