Aplicação da cromatografia de permeação em gel na avaliação da interação entre metais pesados e a matéria orgânica - Lagoa de Patos, RS, Brasil

Abstract

Gel permeation chromatography method was applied to evaluate the Zn metal distribution levels in the organic fraction from sediments collected in the Patos Lagoon estuary. The analysis was performed based in metal distribution levels comparing with the dissolved organic carbon one and the molecular mass of the organic fraction. Initially, it was considered the analysis of three different metals: Cu, Pb and Zn. Nevertheless, while Cu and Pb levels were below the detection limit, Zn concentration ranges from 5 to 205 µg L1 . In this study was analyzed four different points: I {[Zn] = 4.88-24.47 µg L-1} and II {[Zn] = 11.33- 91.06 µg L-1} in north region; III {[Zn] = 5.82-39.26 µg L-1} and IV {[Zn] = 22.78-205.41 µg L-1} in south region. The Zn levels in south were ten times higher than in north region, which is due to several industrial and port activities in this area. In both regions, there are significant amounts of Zn associated with the organic fraction (1.8 Da-1.4 kDa), while in south region there is a high level of Zn in its free form. It is important to comment that Zn complexation in the estuary was highly variable between north and south region (Lagoon estuary), which may be attributable to the lower salinity level in north region when compared with south one.