K14d Diagnóstico da concentração de HPAs e íons metálicos em sedimentos do Lago de Itaipu-PR

Abstract

Sediments are an environmental segment of great interest in aquatic ecosystems, since they can accumulate and remobilize contaminant species that enter bodies of water through various natural and man-made sources. Some of these contaminants are adsorbed in the sediments, for example the HPAs and the metallic elements. The HPAs are considered priority organic pollutants in environmental studies because they can cause mutations and tumors in biological systems. The presence of metallic elements in the environment permits bioaccumulation and biomagnification in the food chain, causing disturbances in the metabolic processes of living organisms. The object of this study was to diagnose the degree of contamination by metal ions, using FAAS and the extraction and quantification of HPAs through HPLC in samples of sediment collected at nine separate points along the Lago de Itaipu (Lake Itaipu). Concentrations of the elements Al, Fe, Mn, Cu, Pb, Zn, Cd, Ni and Cr were evaluated, along with the 16 HPAs considered to be priority in function of their carcinogenic nature. Physiochemical parameters (pH, COT, MO, PT and granulommetry) were determined for characterization of the samples. The fractions of environmentally biodisponible metallic ions were analyzed using HCl 0,1mol.L?¹ as an extractor, and the pseudo-total fractions using concentrated HNO3 and H2O2 30% v/v. The quantification of metal biodisponibility ions in the sediment revealed levels that were always below the PEL limit, at which there are likely biological effects to the aquatic environment. For the pseudo-total fraction, the elements Cr, Cu and Ni exceeded this limit. Analysis of the HPAs showed that these organic substances were present in low concentrations in the region of study, but did not exceed the NEP reference value, above which adverse biological effects are expected. Studies of the ratio between the concentrations of the HPAs indicated pyrolitics and petrogenic sources for these contaminants in the region studied. It was established through granulometric analysis that points 1, 3, 5 and 8 were sand-based, while points 2, 4, 6, 7 and 9 were clay-based. The sediments of the region were organic at collection points 2, 6, 7 and 9 and inorganic all the other points. The levels of total phosphorus varied from 28,12 to 155,73 mg.Kg?¹.