Dataset Information

Effects of Bacillus thuringiensis HC-2 Combined with Biochar on the Growth and Cd and Pb Accumulation of Radish in a Heavy Metal-Contaminated Farmland under Field Conditions.

ABSTRACT: The objective of this study was to explore the effect of heavy metal-resistant bacteria and biochar (BC) on reducing heavy metal accumulation in vegetables and the underlying mechanism. We tested Bacillus thuringiensis HC-2, BC, and BC+HC-2 for their ability to immobilize Cd and Pb in culture solution. We also studied the effects of these treatments on the dry weight and Cd and Pb uptake of radish in metal-contaminated soils under field conditions and the underlying mechanism. Treatment with HC-2, BC, and BC+HC-2 significantly reduced the water-soluble Cd (34-56%) and Pb (31-54%) concentrations and increased the pH and NH4+ concentration in solution compared with their vales in a control. These treatments significantly increased the dry weight of radish roots (18.4-22.8%) and leaves (37.8-39.9%) and decreased Cd (28-94%) and Pb (22-63%) content in the radish roots compared with the control. Treatment with HC-2, BC, and BC+HC-2 also significantly increased the pH, organic matter content, NH4+ content, and NH4+/NO3- ratio of rhizosphere soils, and decreased the DTPA-extractable Cd (37-58%) and Pb (26-42%) contents in rhizosphere soils of radish. Furthermore, BC+HC-2 had higher ability than the other two treatments to protect radish against Cd and Pb toxicity and increased radish biomass. Therefore, Bacillus thuringiensis HC-2 combined with biochar can ensure vegetable safety in situ for the bioremediation of heavy metal-polluted farmland.

SUBMITTER: Li Z

PROVIDER: S-EPMC6801573 | biostudies-literature | 2019 Sep

REPOSITORIES: biostudies-literature

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Effects of <i>Bacillus thuringiensis</i> HC-2 Combined with Biochar on the Growth and Cd and Pb Accumulation of Radish in a Heavy Metal-Contaminated Farmland under Field Conditions.

Li Zigang Z Wang Peng P Yue Xiaoyu X Wang Jingtao J Ren Baozeng B Qu Lingbo L Han Hui H

International journal of environmental research and public health 20190930 19

The objective of this study was to explore the effect of heavy metal-resistant bacteria and biochar (BC) on reducing heavy metal accumulation in vegetables and the underlying mechanism. We tested <i>Bacillus thuringiensis</i> HC-2, BC, and BC+HC-2 for their ability to immobilize Cd and Pb in culture solution. We also studied the effects of these treatments on the dry weight and Cd and Pb uptake of radish in metal-contaminated soils under field conditions and the underlying mechanism. Treatment w ...[more]

PMID: 31574932

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Project description:AimsThe release of heavy metals (such as Pb and Cd) from foliar litter play an important role in element cycling in alpine forest ecosystems. Although natural forest gaps could play important roles in the release of heavy metals from foliar litter by affecting the snow cover during the winter and solar irradiation during the growing season, few studies have examined these potential roles. The objectives of this study were to document changes in Pb and Cd dynamics during litter decomposition in the center of gaps and under closed canopies and to investigate the factors that controlled these changes during the winter and growing seasons.MethodsSenesced foliar litter from six dominant species, including Kangding willow (Salix paraplesia), Masters larch (Larix mastersiana), Mingjiang fir (Abies faxoniana), Alpine azalea (Rhododendron lapponicum), Red birch (Betula albosinensis) and Mourning cypress (Sabina saltuaria), was placed in litterbags and incubated between the gap center and closed canopy conditions in an alpine forest in the eastern region of the Tibetan Plateau. The litterbags were sampled at the snow formation stage, snow coverage stage, snow melt stage and during the growing season. The Pb and Cd concentrations in the sampled foliar litter were determined by acid digestion (HNO3/HClO4).Important findingsOver one year of decomposition, Pb accumulation and Cd release from the foliar litter occurred, regardless of the foliar litter species. However, Pb and Cd were both released from the foliar litter during the winter and accumulated during the growing season. Compared with the gap center and the canopy gap edge, the extended gap edge and the closed canopy showed higher Pb and Cd release rates in winter and higher Pb and Cd accumulation rates during the growing season, respectively. Statistical analyses indicate that the dynamics of Pb were significantly influenced by frequent freeze-thaw cycles in winter and appropriate hydrothermal conditions during the growing season, the dynamics of Cd were strongly influenced by species and the presence of a forest gap at different decomposition stages. These results show that forest gaps could inhibit Pb and Cd release from foliar litter in the alpine forest of western Sichuan. In addition, a decrease in the snow depth in the winter warming scenario would promote the release of Pb during foliar litter decomposition. There exist some difference that may be influenced by litter quality, microenvironment and microtopography during litter decomposition.

Project description:Biochar was widely developed for the soil amendment and remediation of heavy metal contaminated soil. The Cd hyperaccumulator, Solanum nigrum L., has been paid much more attention with the wide application of phytoremediation. The effects of biochar on the growth and accumulation capacity of Solanum nigrum L. in Cd contaminated soil have not been explored so far. The objectives of this study were to explore the dual effects of biochar addition on available Cd in the soil and hyperaccumulation of Cd in Solanum nigrum L. under different Cd contaminated levels. The correlations of soil physicochemical and biochemical properties and Cd absorption of Solanum nigrum L. were analyzed after a 60-day pot experiment under three biochar doses (0%, 1% and 5%) and four Cd concentrations (0, 25, 50 and 100 mg kg-1). The availability of Cd obtained by DTPA extraction significantly decreased after biochar application (P = 0.003, P = 0.0001, P = 0.0001 under 1% biochar addition for 25, 50, and 100 mg kg-1 Cd concentrations, P = 0.0001, P = 0.0001, P = 0.0001 under 5% biochar addition for 25, 50, and 100 mg kg-1 Cd concentrations, n ≥ 3). The 1% biochar dose significantly increased leaf dry weight (P = 0.039, P = 0.002 for the Cd concentrations of 50 and 100 mg kg-1, n ≥ 3) compared with the control in higher Cd concentrations (50 and 100 100 mg kg-1). In the presence of biochar, the bioconcentration factor (BCF) increased under the Cd concentrations of 50 and 100 mg kg-1. The translocation factors (TF) decreased with the biochar doses under the Cd concentration of 100 mg kg-1. The dose of 5% biochar significantly increased the urease activity by 41.18% compared to the 1% biochar addition in the Cd contaminated soil of 50 mg kg-1 concentration. The activities of acid phosphatase were inhibited by 1% biochar dose in all the Cd contaminated soils. The dry weight of the root of Solanum nigrum L. was significantly negatively correlated with acid phosphatase activity and BCF, respectively, indicating acid phosphatase in the rhizosphere soil of Solanum nigrum L. were repressed by Cd toxicity despite of biochar amendment. Biochar had no negative effect on Cd accumulation ability of Solanum nigrum L. Two-way ANOVA analysis showed that both biochar and Cd significantly affected the height of Solanum nigrum L. and the dry weight of leaf and stem. This study implied that biochar addition does not limit the absorption of hyperaccumulator Solanum nigrum L. in the remediation of Cd-contaminated soil. This study implied that the simultaneous application of biochar and hyperccumulator Solanum nigrum L. is promising during the remediation of Cd-contaminated soil.

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Dataset Information

Effects of Bacillus thuringiensis HC-2 Combined with Biochar on the Growth and Cd and Pb Accumulation of Radish in a Heavy Metal-Contaminated Farmland under Field Conditions.

Publications

Effects of <i>Bacillus thuringiensis</i> HC-2 Combined with Biochar on the Growth and Cd and Pb Accumulation of Radish in a Heavy Metal-Contaminated Farmland under Field Conditions.

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