Análises de metais pesados em corpos hídricos urbanos na cidade de Cascavel

Abstract

Understanding traces of metals in urban water bodies has been crucial to comprehend the impact of anthropogenic activities, mostly in persistent pollutants context. This is especially important when these water bodies serve as the primary water supply due to their proximity to urban environments. Thus, this study aims at evaluating the potential ecological risk and their respective sources of contamination by heavy metals in urban water bodies in the of Cascavel city, Paraná. The treatments included spatial points (urban spring, urban median thalweg, and urban mouth) of six rivers in Cascavel-PR: Cascavel and Quati Rivers, Rio, Bezerra streamlet, River of Antas, Lageado Clarito, and Sanga Amambay. Samples were collected in eight replications using an Ekman dredger collector and well packaged to be transported and analyzed regarding texture, carbon dioxide, and heavy metal concentrations. Chemical elements such as cadmium (Cd), copper (Cu), lead (Pb), chromium (Cr), iron (Fe), manganese (Mn), nickel (Ni), and zinc (Zn) were quantified by atomic absorption spectrometry. While heavy metal values were compared with the ones established as limits by CONAMA. Heavy metals concentrations along the studied rivers at the spring, median thalweg, and at the river mouth were related to soil particle size, hydrodynamics, total organic carbon, and anthropogenic activities. Copper and nickel levels exceeded level-2 limit when compared to the ones established by CONAMA in all rivers, indicating a need for monitoring. In contrast, cadmium, lead, and chromium did not exceed the level 2 limit and are not a cause for concern. While cadmium, lead and chromium did not exceed the level-2 limit, thus, they are not a problem yet. Iron levels were substantially high in all studied rivers, consequently, regular and thorough monitoring must occur, likely due to geogenic effects.