title: Inherent organic compounds in biochar--Their content, composition and potential toxic effects.
abstract: Pyrolysis liquids consist of thermal degradation products of biomass in various stages of its decomposition. Therefore, if biochar gets affected by re-condensed pyrolysis liquids it is likely to contain a huge variety of organic compounds. In this study the chemical composition of such compounds associated with two contaminated, high-volatile organic compound (VOC) biochars were investigated and compared with those for a low-VOC biochar. The water-soluble organic compounds with the highest concentrations in the two high-VOC biochars were acetic, formic, butyric and propionic acids; methanol, phenol, o-, m- and p-cresol, and 2,4-dimethylphenol, all with concentrations over 100 μg g(-1). The concentrations of 16 US EPA PAHs determined by 36 h toluene extractions were 6.09 μg g(-1) for the low-VOC biochar. For high-VOC biochar the total concentrations were 53.42 μg g(-1) and 27.89 μg g(-1), while concentrations of water-soluble PAHs ranged from 1.5 to 2 μg g(-1). Despite the concentrations of PAHs exceeding biochar guideline values, it was concluded that, for these particular biochars, the biggest concern for application to soil would be the co-occurrence of VOCs such as low molecular weight (LMW) organic acids and phenols, as these can be highly mobile and have a high potential to cause phytotoxic effects. Therefore, based on results of this study we strongly suggest for VOCs to be included among criteria for assessment of biochar quality.
authors.affiliation: UK Biochar Research Centre, School of Geosciences, University of Edinburgh, Crew Building, Alexander Crum Brown Road, Edinburgh EH9 3FF, UK.
authors.forename: Wolfram
authors.initials: W
authors.lastname: Buss
authors.affiliation: UK Biochar Research Centre, School of Geosciences, University of Edinburgh, Crew Building, Alexander Crum Brown Road, Edinburgh EH9 3FF, UK. Electronic address: ondrej.masek@ed.ac.uk.
authors.forename: Ondřej
authors.initials: O
authors.lastname: Mašek
authors.affiliation: School of Geosciences, University of Edinburgh, Crew Building, Alexander Crum Brown Road, Edinburgh EH9 3FF, UK.
authors.forename: Margaret
authors.initials: M
authors.lastname: Graham
authors.affiliation: Institute of Agricultural Engineering, Conversion Technology and Life Cycle Assessment of Renewable Resources, University of Hohenheim, Garbenstrasse 9, 70599 Stuttgart, Germany.
authors.forename: Dominik
authors.initials: D
authors.lastname: Wüst
mesh_terms: D000821:Animal Feed / Q000032:analysis; D002606:Charcoal / Q000737:chemistry*; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis* / Q000633:toxicity; D012987:Soil / Q000737:chemistry; D012989:Soil Pollutants / Q000737:chemistry* / Q000633:toxicity; D055549:Volatile Organic Compounds / Q000032:analysis* / Q000633:toxicity
chemical_list: D011084:Polycyclic Aromatic Hydrocarbons; D012987:Soil; D012989:Soil Pollutants; D055549:Volatile Organic Compounds; C540010:biochar; D002606:Charcoal
keywords: Biochar; Contaminant; PAH; Pyrolysis; Re-condensation; VOC