Fires make the soil impermeable and cause the displacement of ashes, which can carry harmful substances, spreading contamination to aquifers and other areas.
Fires substantially alter the characteristics of the surface layer of the soil, which is generally the most fertile, and make the affected land impermeable. This is demonstrated by research carried out after the Doñana fire by scientists from the MED Soil Research Group (University of Seville) and the Soil and Sediment Organic Matter (MOSS) of the Institute of Natural Resources and Agrobiology of Seville (IRNAS-CSIC), as published in the newspaper El País.
Cuesta Maneli, area near Doñana, burned after the fire. Source: EUROPA PRESS
According to this study, the flames convert permeable soil into hydrophobic soil by altering the molecular composition of organic matter and the proportion of long-chain fatty acids. This modification explains the formation of the so-called “chapapote de monte”, the sludge of ashes and fine sediments that appears in disaster areas. Subsequently, with rainwater, the debris left by the fire is washed into aquifers, rivers and the coast, which in turn are also affected with harmful substances, spreading environmental pollution. In places where there is no rainfall, the toxic material mixes with the soil, already altered by the fire.
This study allows us to address more effectively the restoration work, which should not only focus on restoring the vegetation cover, but also on soil remediation. The head scientist at IRNAS, José Antonio González Pérez, points out that “despite being so close to us and being a fundamental resource for life, the soil on which we live is largely unknown. Apart from being the basis for the production of food and fibers for our clothes, it filters the water we drink, stores it and also prevents floods and droughts and combats global climate change by fixing greenhouse gases”.
