Assessment of the bioavailability of metals in sediments of mangrove area of the Estuarine Complex of Suape, Pernambuco.

Abstract

Mangroves are known areas of deposition of terrestrial and marine materials, being thus potentially accumulators of heavy metals. Moreover, they are a major source of debris which forms the basis of most tropical coastal food chains. Thus, metals accumulated in mangroves can potentially contaminate such chains and reach human beings. For this reason, their determination is an important factor for the establishment of quality standards and for the control of pollutants in general. In order to contribute to the study of these environments sediments from mangroves and from the Massangana and Tatuoca Rivers in the area of the Industrial Portuary Complex of Suape, in the State of Pernambuco - Brazil were analyzed. The concentrations of the metals Cd, Pb, Al, Zn and Fe were determined by atomic absorption spectrometry. The levels obtained for [Cd (< 0.10 mg.kg-1), Pb (<0.05 mg.kg-1 – 3.14 mg.kg-1), Mn (12 mg.kg-1– 65 mg.kg-1), Zn (<0.04 mg.kg-1), Fe (710 mg.kg-1 - 15000 mg.kg-1), Al (1100 mg.kg-1 – 1600 mg.kg-1] were compared with some international reference values (National Oceanic and Atmospheric Administration - NOAA and Summary of Existing Canadian Environmental Quality Guidelines), which showed concentrations below the established levels, suggesting no bioavailability of these metals to the biota. The variation of the sea tides and the particle size of the samples may still hinder the accumulation of these metals in the sediment of the region. However, these levels can be harmful to benthic organisms which are fixed to the substrate being, therefore, more susceptible to contamination.