Determination of heavy metals (fe, mn, cd, cu, co, cr, ni, zn and pb), organic matter and organic carbon in the sediment of mangrove areas in Vigia de Nazaré City, NE–PA

Abstract

Contamination and assessment of metals in the sediment of aquatic ecosystems is an important indicator of environmental contamination occurring in locations close to urban areas. The study aims to characterize and quantify the levels of heavy metals (Fe, Mn, Cd, Cu, Co, Cr, Ni, Zn and Pb), at the bottom sediment at Furo da Laura, city of Vigia de Nazaré (PA), the area is considered of great importance for the hydrographic complex, as it is an estuary that receives contribution from the Marajó Bay. Nine sediment samples were collected and sieved in the clay fraction <63 μm. From each site, 0.5g was selected to be subjected to acid digestion, and the metal determinations were performed by flame atomic absorption spectrometry with atomization, partial extraction. The determinations of organic matter and organic carbon used as a reference the Walkley-Black method. High concentrations of Fe and Mn suggest the characteristic of lateritic soils in the region, and only the concentrations for Pb (P3, P4 and P7) and Ni showed values above the tolerable limit stipulated by CONAMA Resolution No. 454/12, Level 1. However, these results are still considered concentrations below which adverse effects on the ecosystem are expected, but which suggests the anthropogenic contribution, whose probable sources of releases are domestic and industrial effluents, and also, coming from river transport activities. It is recommended that the area be monitored so that the behavior of these metals can be monitored.