Thermally Modified Calcium Oxalate Phytoliths as Markers for Biomass Fire Sources

Calcium oxalate phytoliths are present in more than 217 different families of plants. They concentrate in the bark and leaves, which are also the parts of plants that are consumed in wildfires and contain the highest ash content. Phytoliths have a variety of shapes, forms, or crystal habits based on the plant part where they occur and the genetics of the plant. The shape of the phytoliths are retained even after exposure to high temperature that changes their chemical composition and alters the optical properties of the phytolith. Thermally modified calcium oxalate phytoliths indicate the types of plants (and plant parts) that have burned, as well as the type of temperature transition and intensity of the combustion, making the presence or absence of thermally modified phytoliths useful for identifying debris from the smoke of specific wildfires and combustion sources.