Critical Reviews in Environmental Science and Technology · 2019 · 280 citations · 319 references
AgricultureEnvironmental EngineeringSoil SciencesSoil ChemistrySoil RemediationSoil ScienceBioremediationContaminated Soil RemediationSoil Chemical PropertiesSoil ContaminationSoil PhSoil PollutionBiochar AmendmentsBiochar ImmobilizationBiochar-amended MediaBiochar-based RemediationImmobilizationMicrobial ImmobilizationPotentially Toxic ElementsSoil Organic Matter Content
Biochars are increasingly used to remediate contaminated soils and waters, yet while chemical immobilization mechanisms in aqueous media are well defined, those in soil matrices are more complex and the biological interactions with PTEs remain poorly understood, with effectiveness depending on biochar properties, application rates, and soil factors such as organic matter, clay, pH, and redox potential. This review seeks to overview the factors governing biochar–PTE interactions, the synergistic role of microorganisms, and to highlight analytical methods and future research directions for understanding biochar–PTE interactions in polluted soils. The authors discuss how biochar characteristics, application rates, and soil conditions influence immobilization, and review analytical techniques for probing molecular interactions between biochar and PTEs. Modified biochars can outperform pristine ones in immobilizing PTEs, but may negatively impact soil microbial activity.
The application of biochars for the remediation of water and soils contaminated with potentially toxic elements (PTEs) has seen a recent growing interest. The mechanisms of chemical immobilization of PTEs with biochars in aqueous media have been well defined. However, immobilization mechanisms by which biochars interact with PTEs in soil matrix are more complex. The biological immobilization mechanisms and their interactions with PTEs in biochar-amended soils are not as well defined. This review presents an overview of factors governing interactions of biochars with PTEs as well as the synergistic effect of biochars and microorganisms in biological immobilization processes. The effectiveness of biochars in improvement of microbial immobilization of PTEs mainly depends on biochar properties, application rates, and soil environments such as organic matter content, clay type and content, pH and redox potential. Although some modified biochars appear to be better than the pristine biochars for immobilization of PTEs, their potential adverse impacts on soil microbial activity should be considered. This review highlights the most common analytical methods to discover molecular interaction mechanisms between biochar and PTEs and future research areas required for the understanding of biochar-PTE interactions in polluted soil systems.
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