Geoenvironmental impacts of post-wildfire hillslope stabilization with xanthan gum and polyacrylamide

Abstract

Wildfire-burnt hillslopes are vulnerable to erosion, precipitation-induced landslides, and debris flows. Xanthan gum (XG) and polyacrylamide (PAM) were recently shown as attractive alternatives for controlling surface erosion. However, their mobility on the hillslopes or effects on downstream waters are unknown. This study showed that after three wet-dry cycles, vertical movement of XG and PAM into the soil with rainfall is possible. Controlled water quality experiments showed that XG could have negative impacts on acidity and turbidity if its concentration in water is 0.25% or higher. Both additives showed potential concerns related to total nitrogen at concentrations of 0.25% (XG), 0.1% (PAM), and higher. Further, even at the lowest concentration (0.01%), both increased the total organic carbon concentration, which can be problematic for water treatment and control of toxic disinfection byproduct formation. However, further research is needed as the benefits of controlling post-fire erosion may overcome the water quality degradation from XG and PAM seen in controlled experiments.

Citation

Ahmed, Alishan; Hohner, Amanda K.; Robichaud, Peter R.; Akin, Idil Deniz. 2022. Geoenvironmental impacts of post-wildfire hillslope stabilization with xanthan gum and polyacrylamide. In: Lemnitzer, Anne; Stuedlein, Armin W., eds. Geo-Congress 2022: Geoenvironmental Engineering; Unsaturated Soils; and Contemporary Topics in Erosion, Sustainability, and Coal Combusion Residuals. American Society of Civil Engineers. p. 50-59.