Analysis of contaminants in surface water after the collapse of the Córrego do Feijão mine dam in Brumadinho, Brazil

Abstract

This manuscript presents results on surface water quality in the Paraopeba River basin, Brazil, following the environmental disaster caused by the dam collapse at the Córrego do Feijão mine in Brumadinho. Surface water samples were collected at 52 points along the river and analyzed to determine the presence of organic compounds according to the guidelines outlined in CONAMA Resolution 396. Liquid and gas chromatography with sequential mass spectrometry (UHPLC-2D-MS/MS and GC–MS/MS, respectively) were employed to identify and quantify volatile, semi-volatile, and non-volatile organic compounds in the water samples. The results revealed the presence of several organic compounds, some of which exceeded the maximum allowable concentrations. Most semi-volatile compounds analyzed were within regulatory limits, although some were near the maximum permissible thresholds. Polycyclic aromatic hydrocarbons (PAHs), including Benzo(a)anthracene, Benzo(a)pyrene, and Chrysene, were found at concentrations indicative of combustion residues. Additionally, pesticide residues such as organophosphates and triazines were quantified, pointing to agricultural influence in the basin. Organochlorine compounds banned in Brazil, such as dieldrin, aldrin, DDT, and lindane, were still detected in the samples, evidencing their environmental persistence. The compounds with the highest detection frequencies were 2,4,6-trichlorophenol (415 samples), pentachlorophenol (259 samples), and lindane (188 samples). Peak concentrations were observed for 2,4,6-trichlorophenol (11.0 μg L⁻¹), cis-dichloroethene (82.2 μg L⁻¹), trans-dichloroethene (10.3 μg L⁻¹), and alachlor (6.2 μg L⁻¹), raising concerns about their persistence and potential toxicity. These findings highlight the importance of continuously monitoring surface water quality in areas affected by environmental disasters to ensure the safety of water consumers.