An exploratory study into ash mobilization using lysimeters

Abstract

Wildfires burn vegetation and leave the resultant organic and inorganic ash into the soil surface. Depending on the temperatures and burn durations, the quantity and type of ash can vary widely. Ash mobilization following wildfire is a topic of major concern, since it may result in contamination of surface water bodies within and downstream of the burnt areas. The present study aims to analyse the influence of black and white ash on surface runoff, leachate and total erosion and erosion of organic matter by running a field experiment along 6 weeks, using three replicate lysimeters with control soil, soil with addition of black ash and soil with addition of white ash. There was some suggestion but no statistical evidence that black ash reduced overland flow generation during the initial rainfall events, while black ash was found to increase sediment and organic matter losses by overland flow in a statistically significant manner. This was not during the initial rainfall events and, therefore, not directly related to the presence of a homogenous cover of a well-defined ash layer on the soil surface.

Introduction to the special issue on fire impacts on hydrological processes

“…This special issue presents research on the impact of fire on the Earth System. Most of the special issue (Caltabellotta et al, 2022;Ebel et al, 2022;Godoy et al, 2022;Li et al, 2022;Lucas-Borja et al, 2022;Sanin et al, 2022) is devoted to the impact of wildfire or prescribed fire on hydrological processes. The remaining articles are devoted to the heat-induced changes in soil properties (Fajković et al, 2022;Hološ et al, 2022) and the impact of biochar (produced by pyrolysis/heating biomass in the total or partial absence of oxygen) amendment on soil organic molecular markers (Atanassova et al, 2022).…”

“…This strongly indicates that wildfire can act as a trigger for remobilization of heavy metals. Godoy et al (2022) completed a plot-scale study of ash effects on surface runoff, leachate, total erosion, and erosion of organic matter using natural rainfall in the Aveiro region of north-central Portugal. Wildfire and industrial wood ash were applied atop non-fire affected soil, sand, and gravel in lysimeters.…”