Biochar: Environmental and Socio-Economic Issues

The toxins question

Two toxins are especially of concern with regard to biochar because they are associated with combustion processes. They are polycyclic aromatic hydrocarbons (PAHs) and dioxins. How often these are found in charcoal and in what concentrations is, according to CSIRO, “inadequately researched”. While charcoal samples have been found to contain PAHs, CSIRO says these are “not at environmental risk level.” However, it adds, “a more systematic evaluation for a more complete range of other potentially harmful chemical contaminants associated with combustion, as well as toxic substances within feedstocks, has not been made.”

Similarly, an environmental risk assessment of the impacts of these toxins on terrestrial or aquatic ecosystems has not been done. CSIRO says that such an assessment is critical for three reasons: “the irretrievability of biochar once added to soil, the apparent general permanency of biochar once in the soil and the scale and speed at which the strategy needs to be implemented to contribute to climate change mitigation.”

Resources

• See main page: Biochar
• Biochar: Carbon Sequestration
• Biochar: Effects on Soil and Crops
• Biochar Lobby