Estudo dos hidrocarbonetos policíclicos aromáticos (HPA) em amostras de água e material particulado em suspensão no rio Aurá, Belém – PA.

Abstract

Polycyclic aromatic hydrocarbons (PAH) are ubiquitous organic contaminants generated by natural and anthropogenic processes. They are formed, mainly, during the decomposition of organic matter which is induced by high temperatures. They are persistent compounds that can be transported over long distances. The US Environmental Protection Agency (US EPA) considers sixteen of these PAH, because of their toxic, mutagenic and carcinogenic properties. The objective of this study was to evaluate the environmental contamination by PAH in the Aurá river, against the levels established by the legislation, and its possible sources in water samples and in suspended particulate matter (SPM). Ten samples of water and SPM were collected in two distinct seasons (rainy and less Rainy). The extraction techniques used were automated SPE for water samples and microwave assisted extraction for the SPM samples. Samples were analyzed in Gas Chromatography coupled to a Mass Spectrometer with Triple quadropole. In water the concentrations of PAH found were below the detection limit of the equipment. PAH total concentrations founded in SPM ranged from 31.71 to 2.498,15 μg L-1 in the Less Rainy season and from 31.71 to 2865.84 μg L-1 in the rainy season. Discrimination of PAH sources and their toxicity potential are required to assess their effects on the environment. The PAH sources tended to be associated with petrogenic source but were classified as mixed, petrogenic and pyrolytic sources, due to the responses obtained with the diagnostic ratios applied. Previous studies carried out on the bottom sediment of the Aurá River, while the landfill was in operation, showed a predominance of PAH from pyrogenic origin while the results obtained in this study after the landfill deactivation showed a higher concentration of petrogenetic sources indicating the influence of the landfill on the study area.