Acúmulo e potencial de mobilidade de metais pesados e nutrientes em sedimentos do Sistema Tietê-Pinheiros, SP (reservatórios Billings, Pirapora, Rasgão e Barra Bonita)

Author(s)

Ivone Silveira da Silva

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Conjunto das Químicas (IQ e FCF) (CQ/DBDCQ)
• Defense date: 2000-09-26

Examining board members

Jorge Cesar Masini; Lucio Angnes; Marcio Antonio Augelli; Jose Roberto Guimaraes; Wilson de Figueiredo Jardim

• Advisor: Jorge Cesar Masini

Abstract

The aim of this phD thesis was to assess the accumulation levels and the geochemical distribution of heavy metais and nutrients in sediment profiles of the Tietê-Pinheiros River System, in São Paulo State. Samples were submitted to a single extraction with 0,1 mol L-1 hydrochloric acid and a sequential extraction procedure. The concentrations of sulphides, carbon, phosphorus, nitrogen were determined in order to identify the chemical mechanisms involved in the heavy metais distribution in these sediments. It was also carried out an assessment of the surface and bottom waters quality based on nutrients (C, N, P and S), metals and dissolved oxygen concentrations. The obtained results indicated a high grade of contamination for Cd, Zn, Pb and Cu in sediments from Billings, Pirapora and Rasgão reservoirs. In these environments, heavy metals are associated in greater extension with reactive forms such as sulphides, carbonates or adsorbed to oxihydroxides of iron and manganese or they form complexes with organic matter. The residual fraction was the main form of heavy metais association in sediments from Barra Bonita reservoir, which presented a high grade of contamination for Cd. (AU)