Avaliação da concentração de nutrientes, metais pesados e hidrocarbonetos policíclicos aromáticos nos sedimentos de fundo do lago água preta (Belém- Pará).

Abstract

In aquatic ecosystems the bottom sediments represent the main compartment of accumulation, reprocessing and transfers of heavy metals, nutrients and organic compounds, in this sense has developed several studies to measure the risks that they may offer to aquatic biota. Therefore the present work was to evaluate the concentrations of heavy metals, nutrients and polycyclic aromatic hydrocarbons (PAH's) in bottom sediments of Água Preta lake, located in Metropolitan Region of Belém do Pará state, more specifically in the area of environmental park in Belém. This waterbody is responsible to Bolonha Lake for water supply of the entire metropolitan area of Belém. The concentrations of heavy metals were obtained by emission spectrometry with inductively coupled plasma mass spectrometry (ICP-MS), now in HPAS analysis was used the EPA 8100 method with liquid-liquid extraction and injection (GC-FID) automated. The metals with the highest concentrations were chromium (245 mg.Kg-1) and nickel (97 mg.Kg-1), these indices were above the TEL and PEL, indicating a frequency in the occurrence of adverse effects on aquatic biota, thus as the values of heavy metals nutrients also showed high concentrations, with maximum 6018.67 mg.Kg-1 for total nitrogen and 1674.56 mg.Kg-1 for total phosphorus. In short, the work showed the reflection of anthropogenic pressures, whose the Água Preta lake has suffered over the years, showing that the bottom sediments are impacted by heavy metals, high loads of organic matter and nutrients, what potentiates the eutrophication process. This whole scenario points to the need of intensification of the surveillance in the vicinity of the springs, in addition to monitoring of its environmental quality, seeking to extend the life cycle of the main water supply of the region.