Abstract
The remediation of heavy metal-contaminated soils has attracted increased attention worldwide. The immobilization of metals to prevent their uptake by plants is an efficient way to remediate contaminated soils. This work aimed to seek the immobilization of cadmium in contaminated soils via a combination method. Flask experiments were performed to investigate the effects of hydroxyapatite (HAP) and the Cupriavidus sp. strain ZSK on soil pH and DTPA-extractable cadmium. Pot experiments were carried out to study the effects of the combined amendment on three plant species. The results showed that HAP has no obvious influence on the growth of the strain. With increasing concentrations of HAP, the soil pH increased, and the DTPA-extractable Cd decreased. Via the combined amendment of the strain and HAP (SH), the DTPA-extractable Cd in the soil decreased by 58.2%. With the combined amendment of the SH, the cadmium accumulation in ramie, dandelion, and daisy decreased by 44.9%, 51.0%, and 38.7%, respectively. Moreover, the combined amendment somewhat benefitted the growth of the three plant species and significantly decreased the biosorption of cadmium. These results suggest that the immobilization by the SH combination is a potential method to decrease the available cadmium in the soil and the cadmium accumulation in plants.
Highlights
Various physical, chemical and biological techniques have been used to remediate heavy metal-contaminated soils[1]
The cadmium-contaminated soil was collected from gardens near the Zhuzhou Smelter in Hunan Province, China (113°4′23.46′′E, 27°51′54.3′′N)[18]. It is classified as Ferralsols, according to the World Reference Base for soil resources (WRB)[19]
The soil was cleared of plant debris and stones, air dried at room temperature, and ground to a particle size 2 mm for the experiments
Summary
Chemical and biological techniques have been used to remediate heavy metal-contaminated soils[1]. In situ immobilization is generally considered a feasible technique to remediate metal-contaminated soils due to its cost effectiveness and ease of operation[13]. Identifying combinations of chemical and biological materials to compensate for these shortcomings has been a popular approach with respect to the immobilization of soil metals. ZSK was isolated from heavy metal-contaminated soils[16]. It was indicated that this strain is highly tolerant to five heavy metals (Cd, Cu, Zn, Cr, and Pb) and is a potential microorganism to adsorb cadmium ions[16]. The potential application of the combined amendment of this strain and HAP was investigated for the immobilization of soil cadmium
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