Water and fire are two elements that do not mix, but they affect each other and can greatly harm the health of people and all life forms on Earth. Water is an essential element for life, but excessive use of water can have many negative consequences, such as the recent floods in Brazil. Fire has already been manipulated by primitive people for thousands of years, and today it is an essential tool for various human activities. However, if used without proper control or in criminal ways, it can also be extremely harmful and dangerous.
The results of recent studies show the interactions between these two elements, and mainly the negative effects of fire on water on our planet. Many scientific articles have mentioned the effect of fires in reducing the amount of available water, which affects, among other aspects, air humidity. These consequences are largely linked to climate change and global warming itself.
What about water quality? Little. Since fire and water do not mix, it is the residue left by the fire that reacts with the water, causing direct interference and a decrease in its quality.
The effects of forest fire ash on water resources have been widely studied in temperate regions, Europe and the United States. In Brazil, the topic gained importance within the scope of the research project “Fires and water resources in the Cerrado: ash effects on climatic and ecotoxicological aspects” (2010-2012), and later in the “Ash Project: Motivational aspects of the use of fires and their effects on water and soil as subsidies to mitigate this practice in agriculture” (2013-2016), both led by Embrapa Cerrados (DF) and funded by the National Council for Scientific and Technological Research (CNPq).
However, there are still many gaps to be filled and many questions to be investigated. Fires are known to be frequent and natural events in the Brazilian Cerrado region, for example, but human action has increased their frequency and generated numerous environmental problems. In addition to the losses seen after the fire has ended, effects that are not easily visible have also been discovered. The ash and soot produced by a fire are composed of chemical elements that are components of burned living organisms (vegetables or animals) or even mineral materials, which can decompose depending on the intensity of the fire.
With rainfall, or even airborne, some of this material reaches water resources, carrying a series of chemical elements capable of changing the quality of the water, harming its suitability for drinking and, most importantly, the survival of the species that inhabit it. They inhabit aquatic ecosystems. The presence of macronutrients such as potassium, phosphorus and nitrogen, as well as micronutrients such as various minerals, is observed in the ash, and the available quantities of each of these elements is the most important aspect to determine the consequences.
When in contact with water, some of these compounds dissolve, altering many of the physical and chemical factors of the aquatic environment, including pH and dissolved oxygen, which limits the survival of some species. In this case, environments with low flow or water flow, such as lakes, ponds, and reservoirs, may be most at risk.
Groundwater contamination by ash has also been studied, and this may be a point of concern in terms of gastrointestinal disturbances in individuals consuming well water, or even a problem for irrigators using this water, as elements such as calcium and magnesium can harm the operation of irrigation equipment.
Data on human behaviour suggest that the misuse of fire can and should be reduced, particularly with increased involvement of public bodies, through enhanced educational and environmental education activities for communities, as well as combating practices that can harm the environment and human health.
The fact is that the balance in the interaction between water, fire and human actions urgently needs to be re-established, in order to reduce the observed damage, and thus ensure human survival and the environmental sustainability of the planet.
*Eduardo Sereno Oliveira-Fello is a researcher at Embrapa Cerrado.Image – Source: Embrapa Cerrados Communication
