Avaliação integrada da qualidade da água: influência de parâmetros físico-químicos, metais pesados e impactos ecotoxicológicos em diferentes condições de vazão do Rio Lonqueador, Região Sul do Brasil

Abstract

The Lonqueador River region, located in the southwest of Paraná, is subject to various forms of anthropogenic interference, such as improper land use, the discharge of industrial waste, and unsustainable agricultural practices. In order to better understand the impacts of these activities on water quality, this study carried out an integrated assessment based on physicochemical analyses and ecotoxicological assays, using different bioindicator organisms. Samples were collected at seven points along the river during both high and low flow periods, allowing for the evaluation of how flow variability influences the presence and effects of contaminants. The seasonal approach is essential, as it helps assess the dilution of pollutant concentrations, which significantly affects environmental risk. Water is a vital resource for life and for maintaining ecosystem balance, yet conventional treatment methods are not capable of fully removing many pollutants, such as metals, hormones, and pesticides. These substances remain active in the environment and can cause harm to fauna, flora, and even human health. The effects were assessed using the bioindicators Aspergillus nidulans, Artemia salina, Eisenia fetida, Lithobates catesbeianus, Huh7.5 cells, and Allium cepa. The growth of A. nidulans was significantly reduced at several points, correlating with dissolved hormones and metals. A. salina exhibited significant toxicity at P6 and P7 (during low flow) and at P3 (during high flow), associated with turbidity, electrical conductivity, and the hormone E2. The E. fetida assay indicated toxicity at P7, correlated with pH, metals, and organic matter. L. catesbeianus exhibited micronuclei and a reduced mitotic index, indicating mutagenic and cytotoxic effects at multiple sites. Huh7.5 cells showed reduced viability at P7, associated with metals. A. cepa revealed chromosomal aberrations and cytotoxicity correlated with metals and hormones. Among the points analyzed, P3 and P7 showed the highest levels of environmental impact. Point P3 is located in an area heavily influenced by agriculture, with intensive use of chemical inputs. In contrast, point P7 is situated in an urban and industrialized area, near a major road junction, which increases the load of pollutants entering the river both directly and indirectly. These findings reinforce the need for specific environmental management actions and continuous monitoring. Furthermore, it is extremely important to adopt a broader perspective on water quality one that considers not only classical potability parameters but also ecotoxicological effects and emerging pollutants that often go undetected by traditional monitoring systems.