1.
Underlying mechanisms and effects of hydrated lime and selenium application on cadmium uptake by rice (Oryza sativa L.) seedlings.
Huang, G, Ding, C, Guo, F, Li, X, Zhang, T, Wang, X
Environmental science and pollution research international. 2017;(23):18926-18935
Abstract
A pot experiment was conducted to investigate the effects of selenium (Se) and hydrated lime (Lime), applied alone or simultaneously (Se+Lime), on growth and cadmium (Cd) uptake and translocation in rice seedlings grown in an acid soil with three levels of Cd (slight, mild, and moderate contamination). In the soil with 0.41 mg kg-1 Cd (slight Cd contamination), Se addition alone significantly decreased Cd accumulation in the root and shoot by 35.3 and 40.1%, respectively, but this tendency weakened when Cd level in the soil increased. However, Se+Lime treatment effectively reduced Cd accumulation in rice seedlings in the soil with higher Cd levels. The results also showed that Se application alone strongly increased Cd concentration in the iron plaque under slight Cd contamination, which was suggested as the main reason underlying the inhibition of Cd accumulation in rice seedlings. Se+Lime treatment also increased the ability of the iron plaques to restrict Cd uptake by rice seedlings across all Cd levels and dramatically decreased the available Cd concentration in the soil. These results suggest that Se application alone would be useful in the soil with low levels of Cd, and the effect would be enhanced when Se application is combined with hydrated lime at higher Cd levels.
2.
Bioleaching of heavy metals from mine tailings by indigenous sulfur-oxidizing bacteria: effects of substrate concentration.
Liu, YG, Zhou, M, Zeng, GM, Wang, X, Li, X, Fan, T, Xu, WH
Bioresource technology. 2008;(10):4124-9
Abstract
The aim of this study was to determine the effect of substrate concentration (elemental sulfur) on remobilization of heavy metals from mine tailings by indigenous sulfur-oxidizing bacteria. Also, the variation in the binding forms of heavy metals before and after bioleaching was explored. This work showed the laboratory results of bioleaching experiments on Pb-Zn-Cu mine tailings. The results showed that 97.54% Zn, 97.12% Cu, and 44.34% Pb could be removed from mine tailings by the bioleaching experiment after 13 days at 2% w/v substrate concentration. The results also indicated that substrate concentration 2% was found to be best to bacterial activity and metal solubilization of the five substrate concentration tested (0.5%, 1%, 2%, 3%, and 5%) under the chosen experimental conditions. The bioleaching had a significant impact on changes in partitioning of heavy metals.