Bioaccumulation of potentially toxic elements in floating aquatic macrophytes of Guarapiranga Reservoir, São Paulo

Abstract

Macrophytes species play a relevant role in aquatic environments once they incorporate elements that can be a suitable tool for accumulation studies, mainly when it comes to an important and strategic water supply. The main goal of this study was to establish concentration levels of As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, Se and Zn in four species of floating aquatic macrophytes samples at three sampling sites along the Guarapiranga Reservoir. For this purpose, five analytical techniques were tested such as Inductively Coupled Plasma Optical Emission Spectrometry (ICP OES), Inductively Coupled Plasma Mass Spectrometry (ICP MS), Graphite Furnace Atomic Absorption Spectrometry (GF AAS), Thermal Decomposition, Amalgamation, and Atomic Absorption Spectrophotometry and the multielemental characterization of this matrix was undertaken using Neutron Activation Analysis technique (NAA). The results obtained were compared to reference values for aquatic plants and most of the elements exceeded these values, especially at sampling site 01, which is located near the Embu-Guaãu River flow, the main tributary of the reservoir. In relation to comparison among sampling sites and macrophytes species, One-way Anova in Statistical Package for Social Sciences (SPSS) was performed. Output showed significant differences among sampling sites, but not for macrophytes species. Factor Analysis (FA) with Principal Components (PC) extraction method was performed on data using SPSS software. Output suggested possible common source from the As, Co, Cr, Hg, Ni, Pb and Se elements, which composed PC1. PC2 included Cd, Cu and Zn elements and it should be noticed that Cu is frequently used as algicide in the reservoir, as CuSO4. PC3 included only Mn, suggesting distinct behavior of this element. Eventually, this work should be extended to monitoring programs.