Presence of Heavy Metals and Bacteria in the Water and Soil of the Sinos River Basin After Flooding

Introduction: The catastrophic event that affected 2.3 million people and impacted almost all municipalities in the state of Rio Grande do Sul in May 2024 is an example of the effects of climate change on the planet. Considering this period, the study covered the physical-chemical and microbiological monitoring of the waters of the Rio dos Sinos and the soils located in the flooded areas of this basin. Four water samples and eleven soil samples were collected in two campaigns. The first occurred in July 2024 and the second in October 2024. For the water quality of the Rio dos Sinos, the results showed low concentrations of arsenic, cadmium, chromium, copper, nickel, lead, and mercury. The levels of Escherichia Coli and Total Coliforms were > 8 x 101 CFU/100mL at all collection points. Considering the soils, the concentrations of Chromium, Total Coliforms, and Aerobic Mesophilic Bacteria ranged between 2,400 - 107,560 mg/kg; < 1.0 x 101 - 5.4 x 105 CFU/100mL and 2.2 x 104 - 1.1 x 107 CFU/100mL, respectively. The study concludes that the flood influenced the presence of contaminants in the analyzed environmental matrices, especially in soils located in urban areas. Objective: The objective of this study was to investigate the presence of heavy metals and bacteria in the water and soil of the Rio dos Sinos Basin after the May 2024 flood. Theoretical Framework: In this section, the main concepts and theories that underpin the research are presented. Emphasis is placed on extreme weather events, flooding, heavy metals, and bacteria, providing a solid foundation for understanding the context of the investigation. Method: The methodology adopted for this research includes, considering this period, the physical-chemical and microbiological monitoring of the waters of the Rio dos Sinos and the soils located in the flooded areas of this basin. Four water samples and eleven soil samples were collected in two campaigns. The first campaign occurred in July 2024 and the second in October 2024. Results and Discussion: For the water quality of the Rio dos Sinos, the results showed low concentrations of arsenic, cadmium, chromium, copper, nickel, lead, and mercury. The level of Escherichia Coli and Total Coliforms was > 8 x 10¹ CFU/100mL at all collection points. Considering the soils, the concentrations of Chromium, Total Coliforms, and Aerobic Mesophilic Bacteria ranged between 2,400 - 107,560 mg/kg; < 1.0 x 10¹ - 5.4 x 105 CFU/100mL and 2.2 x 104 - 1.1 x 107 CFU/100mL, respectively. Research Implications: The practical and theoretical implications of this research are discussed, providing insights into how the results can be applied or influence practices in the occurrence of extreme weather events. Originality/Value: This study contributes to the literature as it showed the impact of the Rio Grande do Sul flood on water and soil quality. The relevance and value of this research are related to the conclusion of the work, as the presence of contaminants in the analyzed environmental matrices was evidenced, especially in soils located in urban areas.