Diagnóstico da qualidade da água na Região Hidrográfica do Médio Paraíba do Sul

Abstract

The Médio Paraíba do Sul River Basin is situated in one of Brazil’s most industrialized regions. Along its course, the Paraíba do Sul River is subjected to conflicting uses, including water abstraction for public supply and the discharge of domestic and industrial effluents. The intensive and multiple use of water resources have increased pressure on both water quantity and quality, making monitoring a matter of public and environmental health. This study conducted an integrated assessment of water quality, based on physicochemical and microbiological parameters, as well as the calculation of the Water Quality Index (WQI), and non-target screening of organic compounds using comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC×GC/TOFMS). The research was conducted in two phases: in the first phase, 34 points were monitored using a multiparameter probe to assess seasonal influences; in the second phase, water samples were collected from 11 priority points, selected based on the initial results, for in-depth laboratory analyses. The results revealed significant impacts related to urban and industrial pollution, including increased turbidity during the rainy season and reduced dissolved oxygen during dry periods. The presence of Escherichia coli at several points indicated contamination from domestic sewage, even in stretches classified as having “good” water quality according to the WQI, highlighting the limitations of this index in degraded environments. Various organic compounds were identified, such as caffeine, phthalates, atrazine, DEET, and polycyclic aromatic hydrocarbons (PAHs), even at reference points. These findings confirm a scenario of diffuse and multifactorial contamination, reinforcing the need to revise environmental indicators and improve strategies for monitoring and managing water resources in the region.