Química de elementos-traço nos sedimentos do Lago do Parú (Manacapuru - Amazonas), sob influência do pulso de inundação do baixo Rio Solimões Trace elements chemical in Lago do Parú (Manacapuru - Amazonas) sediments, under Lower Solimões River flood pulse influence

Abstract

O objetivo deste estudo foi determinar as concentrações totais e em frações geoquímicas de Fe, Mn, Co, Cu e Zn em sedimentos, coletados nos períodos de seca (2005) e cheia (2006) do Lago do Parú. Nas partículas de sedimento seco ao ar (SSA) The aim of this work was to determine whole and geochemical fractions of Fe, Mn, Co, Cu and Zn concentrations from sediments collected at low (2005) and high (2006) water seasons in Lago do Parú. From < 45 µm air dried sediment particles was made a Tessier et al. (1979) method to sequential extraction, which separates elements in exchangeable, bound to carbonates, bound to iron and manganese oxides, bound to organic matter and residual geochemical fractions. Diluted samples were read in each fraction, by flame atomic absorption spectrometry, where Fe showed the highest whole concentration and strong association with oxides. Mn reached the biggest exchangeable fraction among elements in both analyzed periods. Cu showed strong association by organic fraction and don't presented difference of concentration between periods. Co presented similar behavior of Cu, except for organic fraction, in which showed difference between periods, where was bigger in high water level period. Multivariate statistical analyses confirmed that metals were displaced in sediments geochemical fractions at low and high water seasons.

Keywords

• Metais-traço
• Extração seqüencial
• Lago de planície inundável
• Lago de várzea
• Amazônia central
• Trace metals
• Sequential extraction
• Floodplain Lake
• várzea lake
• Central Amazonia