The occurrence of ash and the use of biochar in the environment has important implications for a range of environmental processes. For instance, on one hand, each year extensive areas all over the world are affected by wildfires and prescribed fire, in which ash is deposited on the soil. On the other hand, the demand for energy is leading to an increased number of biomass power plants, whose ash is increasingly used as a soil amendment. Physicochemical reactions of complex mixtures of mineral and organic compounds (e.g. soil-ash mixtures) can have a range of effects on soils and waters. Importantly, charcoal is relatively recalcitrant and can therefore act as a long-term sink for atmospheric CO2.The complexity of these issues and associated concerns require urgent solutions and knowledge generation about ash and biochar behavior in the environment, especially in a context of climate change. Currently, there is no complete agreement on the terminologies used in the ash and biochar research communities. Due to the obvious overlap and potentials for synergy between ash and biochar research, we consider that it is important to establish clear and unbiased definitions of both concepts in order to strengthen connections and networks among ash and biochar researchers. For example, some researchers consider ash as the inorganic material remaining after combustion while others also include organic material which has not combusted completely. Biochar is the charred residue produced by the pyrolosis of biomass, ideally in the absence of oxygen. Ash and biochar can have a range of effects on soil properties, processes and functions, as well as on the wider environment, including air, surface and groundwater quality. The nature and extent of these effects depend on the type and composition, amount, origin and age of the material, when and where it is released, the subsequent interactions with soil mineral, organic and biological matter, and the way it is influenced by environmental and climatic conditions. This session aims to improve the understanding of the full range of effects of ash and biochar in all environmental components, at different temporal and spatial scales (e.g. from local, to regional and global scales), as well as the underlying factors and mechanisms which control their impacts and dynamics, in terms of behavior, mobility and fate in the environment. Scientific contributions on impacts, environmental behavior, toxicity, mobility, and fate of ash and biochar, in all spheres of the environment, in the form of preliminary results, small and large-scale studies, new methodologies, as well as proposals for future research directions, are welcomed to this session.

We are planning to make a special issue in a international (ISI) journal.

Keynotes

Dr. Frank Verheijen (Department of Environment and Planning & CESAM (Centre for Environmental and Marine Studies,University of Aveiro,Portugal)

Title
"Biochar effects on soils: overview and knowledge gaps"

Dr. Guillermo Rein (School of Engineering, University of Edinburgh, Scotland)

Title
"From peat to char to ash: smouldering wildfires in peatlands"

Prof. Dr. Yakov Kuzyakov

Department of Soil Science of Temperate Ecosystems. University of Göttingen, Germany

Title (provisional)
"Decomposition and transformation of 14C labeled Black Carbon"