Cinzas voadoras: ameaças ao ecossistema avaliadas por testes ecotoxicológicos em zonas úmidas tropicais

Abstract

The increase in ash in the tropical region, mainly caused by fires, associated with the need for a better understanding of the impact of ash on the ecosystem, highlights the importance to carry out more detailed analyzes of the influence of this pollutant in the Pantanal region, one of the largest wetlands on the planet, with an abundant biodiversity. Here, our objective was to elucidate the ecotoxicological effects of ash degradation in tropical wetlands. The impact of this compound on the edaphic system was measured through behavioral and acute toxicity tests in annelids subjected to tropical artificial soil with different concentrations of ash matrix solution. We also sought to assess the impact of ash on the emission of greenhouse gases by the soil. The effect of this pollutant on the water environment was evaluated through acute toxicity tests with Daphnia. Our results allowed the identification of possible effects of ash on tropical organisms. The acute trial resulted in reduced mean mortality rates for Eisenia andrei, with the highest percentage being 25%, although sublethal responses of individuals to the pollutant, such as behavioral and morphological changes, were recorded. The avoidance test allowed the identification of annelid rejection responses to the polluted substrate with the four highest ash concentrations tested, with rejection percentages higher than 50%, with possible indications of damage to the soil function as a habitat. While the acute test with Daphnia similis allowed to record average mortality rates of 100% of the organisms. Additionally, we found a significant increase in greenhouse gas emissions to the atmosphere, with the flow of carbon dioxide increasing as there was an increase in ash concentration, while methane showed a higher emission throughout the experimental period. In addition, changes in soil characteristics were recorded due to the presence of the pollutant and discrepancies in the chemical composition of the ash according to its origin were verified, a fact that may have interfered with the tests performed. Our findings contribute to the understanding of the ecotoxicological impact of ash in tropical areas.