Biochar properties regarding to contaminants content and ecotoxicological assessment.

The objective of the study was the determination of the content of contaminants and toxicity of four different biochars. The properties of the biochars, content of trace metals and polycyclic aromatic hydrocarbons (16 PAHs) were determined. Toxicological estimation of the biochars was performed on the basis of a battery of biotests with plants (Lepidium sativum), bacteria (Vibrio fischeri and 11 different strains from MARA), alga (Selenastrum capricornutum), protozoa (Tetrahymena thermophila) and crustaceans (Daphnia magna). The content of trace metals depended on the biochar and was comparable to uncontaminated soils. PAHs sum varied from 1124 to 28,339 μg/kg. The toxicity of the biochars depended both on their kind and on the test applied. The most sensitive organism was D. magna. Relatively the least sensitive to extracts from the biochars proved to be S. capricornutum and T. thermophila. A significant correlation between the content of PAHs and toxicity was noted only in the case of D. magna.