Estudo sazonal da qualidade de ecossistemas aquáticos no Sul da Amazônia

Abstract

Water is a vital natural resource for the survival of living beings, economic development, and the maintenance of biodiversity. Lentic environments, such as lakes and ponds, play crucial roles in biodiversity and biogeochemical cycles, as well as supporting riparian communities. However, anthropogenic activities, such as minings, deforestation, and the construction of hydroelectric plants, threaten the integrity of these ecosystems. This study assessed water quality throughout a hydrological cycle in four distinct environments in the southern Amazon. Water sampling was conducted monthly between July 2023 and October 2024 at three points in each water body. Physical-chemical and biological parameters were analyzed and subjected to descriptive and multivariate statistical analysis, followed by the application of the Water Quality Index (WQI). Land use and land cover for the year 2023 were also evaluated to identify anthropogenic influences in the surrounding areas. The results showed that temperature, conductivity, phosphate, ammonia, BOD, nitrogen, iron, sulfate, and nitrate did not show significant differences among the environments, while dissolved oxygen, pH, total solids, turbidity, phosphorus, potassium, magnesium, nitrite, and salinity showed significant differences. The Water Quality Index (WQI) ranged from "poor" to "good," with the Beem River showing the lowest values, reflecting greater anthropogenic impact, as seen in land use and occupation. In summary, the lakes maintained more stable conditions, with better indices during the dry season. Multivariate analysis revealed high similarity among the environments, suggesting similar ecological and hydrological characteristics. In conclusion, human interference, especially in the Beem River, requires urgent measures, such as effluent treatment and waste management, while the preservation of native vegetation is essential for the sustainability of the lakes.