Avaliação de risco ambiental e humano por metais potencialmente tóxicos em rios urbanos

Abstract

The environmental impacts on the aquatic ecosystems of the Mangues and Mundaí rivers, located in the municipality of Porto Seguro, resulting from the lack of adequate sanitation and disorderly population growth are notorious. Given this reality and the lack of regular monitoring of water quality in these rivers, the objective of this work is to develop and validate an analytical methodology using the microwave-induced plasma atomic emission spectrometry (MP-AES) technique to to the evaluation of the levels of Al, Cd, Cr, Cu, Fe, Pb, Ni and Zn in fresh water, combination as class II according to CONAMA Resolution 357/2005. The results revealed concentrations higher than regulatory standards in both rivers, highlighting the significant presence of metals such as Al, Cr, Cu, Fe, Pb, Ni and Zn. The environmental risk analysis, carried out using the HeRisk software, highlighted extreme levels of pollution in the Mangues River, especially for Fe at point 1 and for Fe and Ni at point 4. On the other hand, the Mundaí River presented low overall risks, except for Cd at point 1. The Pollution Load Indices (PLI) indicated significant levels of metals in the Rio dos Mangues, while the Rio Mundaí maintained values below 1. The Integrated Threshold Pollution Index (IPITh) indicated a moderate level of pollution for the Rio dos Mangues, contrasting with the low incidence in the Rio Mundaí, in accordance with Brazilian legislation. The assessment of the Potential Ecological Risk Index (PERI) revealed moderate risks to the aquatic ecosystem in specific points of the Rio dos Mangues, mainly due to the concentration of cadmium. The Mundaí River demonstrated a significant absence of risks, resulting in a less impacted aquatic environment. For human risk, an analysis considering oral consideration and thermal contact, covering children and adults. The results highlight oral participation as the main route of exposure, with Cu and Cd presenting the highest non-carcinogenic risks, although they remain below 1, indicating a negligible risk. Pb also presented values below 1, without absence of carcinogenic risk.