A review of biochars’ potential role in the remediation, revegetation and restoration of contaminated soils

• Published in: Environmental pollution (1987) 2011-12, Vol.159 (12), p.3269-3282
• Main Authors: Beesley, Luke, Moreno-Jiménez, Eduardo, Gomez-Eyles, Jose L., Harris, Eva, Robinson, Brett, Sizmur, Tom
• Format: Article
• Language: English
• Subjects: Adsorption; Agriculture; Applied sciences; arsenic; Biochar; Carbon; cation exchange capacity; Charcoal - chemistry; composts; Contaminants; Contamination; Decontamination. Miscellaneous; Density; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Environmental clean-up; environmental impact; Environmental Restoration and Remediation - instrumentation; Environmental Restoration and Remediation - methods; environmental sustainability; Exact sciences and technology; Heavy metals; land restoration; liming; nutrients; oxygen; PAH; polluted soils; Pollution; Pollution abatement; Pollution, environment geology; pyrolysis; remediation; Restoration; soil amendments; Soil and sediments pollution; Soil degradation; Soil Pollutants - chemistry; soil solution; Soils; sorption; Sustainability; temperature
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/j.envpol.2011.07.023

Biochars are biological residues combusted under low oxygen conditions, resulting in a porous, low density carbon rich material. Their large surface areas and cation exchange capacities, determined to a large extent by source materials and pyrolysis temperatures, enables enhanced sorption of both organic and inorganic contaminants to their surfaces, reducing pollutant mobility when amending contaminated soils. Liming effects or release of carbon into soil solution may increase arsenic mobility, whilst low capital but enhanced retention of plant nutrients can restrict revegetation on degraded soils amended only with biochars; the combination of composts, manures and other amendments with biochars could be their most effective deployment to soils requiring stabilisation by revegetation. Specific mechanisms of contaminant-biochar retention and release over time and the environmental impact of biochar amendments on soil organisms remain somewhat unclear but must be investigated to ensure that the management of environmental pollution coincides with ecological sustainability. ► Biochars can reduce mobilities of some organic and inorganic pollutants in soil. ► Source material and production conditions influence pollutant retention. ► Highly alkaline pH and water soluble carbon can undesirably mobilise some elements. ► Large surface area may be toxic to soil fauna but create microbial niches. ► Efficacy of biochar may depend on other organic materials applied in combination. Biochars can reduce the mobility and impact of some soil pollutants but, if applied alone, may fail to support soil restoration, revegetation and hence ecologically circumspect remediation.