Biochar-Facilitated Soil Remediation: Mechanisms and Efficacy Variations
Recent research suggests that biochar amendment is a promising approach to mitigate soil contamination via immobilizing heavy metals and organic pollutants. Through intensive literature review, this paper was aimed to better understand the processes, mechanisms, and effectiveness of biochar in immob...
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doaj-46eb361dc3ed4749b47a48727088c5772020-11-25T03:08:30ZengFrontiers Media S.A.Frontiers in Environmental Science2296-665X2020-10-01810.3389/fenvs.2020.521512521512Biochar-Facilitated Soil Remediation: Mechanisms and Efficacy VariationsMingxin Guo0Weiping Song1Jing Tian2Department of Agriculture and Natural Resources, Delaware State University, Dover, DE, United StatesDepartment of Chemistry, Delaware State University, Dover, DE, United StatesCollege of Chemistry and Materials Science, Sichuan Normal University, Chengdu, ChinaRecent research suggests that biochar amendment is a promising approach to mitigate soil contamination via immobilizing heavy metals and organic pollutants. Through intensive literature review, this paper was aimed to better understand the processes, mechanisms, and effectiveness of biochar in immobilizing chemical contaminants in soil. The quality characteristics of biochar as a soil amendment varied greatly with the feedstock materials and the pyrolysis conditions. Biochar products from different sources demonstrated remarkably diversified capacities and efficiencies for stabilizing soil contaminants. Soil-incorporated biochar was able to stabilize Cd, Cu, Ni, Pb, and Zn and reduce their bioavailability through enhanced sorption (based on electrostatic attraction, ion exchange, and surface complexation) and chemical precipitation (incurred from soil pH elevation and ash addition of carbonates and phosphates). The stabilization efficacy was largely determined by cation exchange capacity, pH, and ash content of the biochar. Biochar amendment increased the mobility of anionic toxic elements [e.g., CrO42-, AsO3-, and Sb(OH)6-] in soil. Soil-incorporated biochar was also able to adsorb non-polar organic compounds (through pore filling, partition, and hydrophobic effect) and polar organic compounds (via H-bonding, electrostatic attraction, specific interaction, and surface precipitation). The adsorption efficiency was controlled by the biochar surface properties specific surface area, microporosity, and hydrophobicity. Biochar may facilitate the mineralization of organic pollutants by enhancing soil microbial activities. The effectiveness of biochar-facilitated soil remediation was case specific, changing with the biochar source, amendment rate, placement, soil type, and pollutant species. More field studies are needed to evaluate the long-term effectiveness of biochar-facilitated soil remediation under practical circumstances.https://www.frontiersin.org/articles/10.3389/fenvs.2020.521512/fullbiocharheavy metalsorganic contaminantsadsorptionimmobilization |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Mingxin Guo Weiping Song Jing Tian |
spellingShingle |
Mingxin Guo Weiping Song Jing Tian Biochar-Facilitated Soil Remediation: Mechanisms and Efficacy Variations Frontiers in Environmental Science biochar heavy metals organic contaminants adsorption immobilization |
author_facet |
Mingxin Guo Weiping Song Jing Tian |
author_sort |
Mingxin Guo |
title |
Biochar-Facilitated Soil Remediation: Mechanisms and Efficacy Variations |
title_short |
Biochar-Facilitated Soil Remediation: Mechanisms and Efficacy Variations |
title_full |
Biochar-Facilitated Soil Remediation: Mechanisms and Efficacy Variations |
title_fullStr |
Biochar-Facilitated Soil Remediation: Mechanisms and Efficacy Variations |
title_full_unstemmed |
Biochar-Facilitated Soil Remediation: Mechanisms and Efficacy Variations |
title_sort |
biochar-facilitated soil remediation: mechanisms and efficacy variations |
publisher |
Frontiers Media S.A. |
series |
Frontiers in Environmental Science |
issn |
2296-665X |
publishDate |
2020-10-01 |
description |
Recent research suggests that biochar amendment is a promising approach to mitigate soil contamination via immobilizing heavy metals and organic pollutants. Through intensive literature review, this paper was aimed to better understand the processes, mechanisms, and effectiveness of biochar in immobilizing chemical contaminants in soil. The quality characteristics of biochar as a soil amendment varied greatly with the feedstock materials and the pyrolysis conditions. Biochar products from different sources demonstrated remarkably diversified capacities and efficiencies for stabilizing soil contaminants. Soil-incorporated biochar was able to stabilize Cd, Cu, Ni, Pb, and Zn and reduce their bioavailability through enhanced sorption (based on electrostatic attraction, ion exchange, and surface complexation) and chemical precipitation (incurred from soil pH elevation and ash addition of carbonates and phosphates). The stabilization efficacy was largely determined by cation exchange capacity, pH, and ash content of the biochar. Biochar amendment increased the mobility of anionic toxic elements [e.g., CrO42-, AsO3-, and Sb(OH)6-] in soil. Soil-incorporated biochar was also able to adsorb non-polar organic compounds (through pore filling, partition, and hydrophobic effect) and polar organic compounds (via H-bonding, electrostatic attraction, specific interaction, and surface precipitation). The adsorption efficiency was controlled by the biochar surface properties specific surface area, microporosity, and hydrophobicity. Biochar may facilitate the mineralization of organic pollutants by enhancing soil microbial activities. The effectiveness of biochar-facilitated soil remediation was case specific, changing with the biochar source, amendment rate, placement, soil type, and pollutant species. More field studies are needed to evaluate the long-term effectiveness of biochar-facilitated soil remediation under practical circumstances. |
topic |
biochar heavy metals organic contaminants adsorption immobilization |
url |
https://www.frontiersin.org/articles/10.3389/fenvs.2020.521512/full |
work_keys_str_mv |
AT mingxinguo biocharfacilitatedsoilremediationmechanismsandefficacyvariations AT weipingsong biocharfacilitatedsoilremediationmechanismsandefficacyvariations AT jingtian biocharfacilitatedsoilremediationmechanismsandefficacyvariations |
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