Análise da Fitotoxicidade das águas do Rio Parnaíba na área de influência das atividades industriais e comerciais do distrito industrial de Teresina/PI

Abstract

Water quality is essential for ecosystem integrity and human uses, and industrial pollution is a frequent aggravating factor in urban areas. In this context, the Parnaíba River—important for water supply, agriculture, and fishing in Teresina (Piauí, Brazil) —may be affected, especially near the Industrial District, where effluent discharges may occur. Therefore, this study aimed to assess the phytotoxicity of Parnaíba River waters before (P1) and after (P2) the influence area of the Teresina Industrial District. Water samples were collected at two sites (November 6, 2025), and Allium cepa L. bioassays were performed, along with pH and electrical conductivity measurements. After seven days of exposure, bulb mass gain, number of roots, root length, and root biomass were evaluated. Physicochemical results indicated neutral pH and low conductivity at both sites, with no statistical differences. However, the bioassay showed a significant reduction in bulb mass gain for onions exposed to P2 water, whereas P1 presented higher biomass gain. Root number, root length, and root biomass did not differ statistically among treatments. In conclusion, although basic physicochemical parameters suggested apparent stability, the lower bulb mass gain at P2 indicates the possible presence of contaminants causing sublethal phytotoxic effects not detected by pH and conductivity, highlighting the need for continuous, integrated monitoring and complementary chemical analyses to identify potential pollutants and support mitigation actions for the Parnaíba River. Keywords: contamination; environmental monitoring; Allium cepa L.