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Elucidating the Potential of Biochar-bentonite Composite and Kaolinite-based Seed Balls for the Remediation of Coal Mining Impacted Heavy Metals Contaminated Soil
Medha, I.; Chandra, S.; Bhattacharya, J. Elucidating the Potential of Biochar-Bentonite Composite and Kaolinite-Based Seed Balls for the Remediation of Coal Mining Impacted Heavy Metals Contaminated Soil. Sustainability2023, 15, 12900.
Medha, I.; Chandra, S.; Bhattacharya, J. Elucidating the Potential of Biochar-Bentonite Composite and Kaolinite-Based Seed Balls for the Remediation of Coal Mining Impacted Heavy Metals Contaminated Soil. Sustainability 2023, 15, 12900.
Medha, I.; Chandra, S.; Bhattacharya, J. Elucidating the Potential of Biochar-Bentonite Composite and Kaolinite-Based Seed Balls for the Remediation of Coal Mining Impacted Heavy Metals Contaminated Soil. Sustainability2023, 15, 12900.
Medha, I.; Chandra, S.; Bhattacharya, J. Elucidating the Potential of Biochar-Bentonite Composite and Kaolinite-Based Seed Balls for the Remediation of Coal Mining Impacted Heavy Metals Contaminated Soil. Sustainability 2023, 15, 12900.
Abstract
Globally, open-pit coal mining is associated with severe land use impact and contamination of soil and water resources with heavy metals. Thus, in growing economies like India, where coal is a significant energy source, the heavy metals contamination of soil and water become ubiquitous. Remediation of such a large stretch of mined-out land is a major challenge and a costly process for the mining industry. In recent years, the application of biochar for the remediation of such heavy metals-contaminated soil has been widely practiced. However, applying biochar and cultivating plants in field conditions becomes challenging.
This study uses a unique remediation approach by developing biochar-bentonite-based seed balls encapsulating Shorgham grass seeds at their core for application in the contaminated soil. The seed ball was developed by using the bentonite biochar composite in varying weight fractions of 0.5 – 5 % with respect to the kaolinite, whose fractions in the seed ball also varied at one, three, and five parts. The seed balls were applied to the pots containing 3 kg of heavy metals contaminated soil for a pot-culture study in a polyhouse for a period of four months. Initial soil analysis results indicated that the mine soil samples showed poor nutrient and organic matter content and were contaminated with heavy metals such as Ni, Zn, Cr, and Cd. Post-pot-culture soil analysis results indicated that the application of seed balls containing five fractions of biochar composite with its combination with three and five-weight fractions of kaolinite showed substantial improvement in the pH, available nutrients, organic matter content, soil enzymes, and overall soil fertility index compared to the controlled study and other cases. The same combination of seed balls also significantly reduced the plant-available fractions of Ni, Zn, Cr, and Cd in the soil and the translocation of these heavy metals from the rhizosphere zone to the grass’s aerial parts, indicating stabilization of heavy metals within the soil matrix. Moreover, the application of seed balls also substantially improved the plant physiology and reduced the release of stress hormones such as proline and glutathione within the plant cells indicating improvement in the plant’s biotic and abiotic stress factors. Thus, the application of seed balls in heavy metals contaminated soils, particularly over a large stretch of land, could be a low-cost and viable remediation technique.
Keywords
biochar; coal mining; heavy metals; remediation; seed balls
Subject
Environmental and Earth Sciences, Pollution
Copyright:
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
