Heavy metals in contaminated soils: sequential extractions

JANAINA F. MARQUES RAPHAEL HYPOLITO About the authors

HEAVY METALS IN CONTAMINATED SOILS - SEQUENTIAL EXTRACTIONS

JANAINA F. MARQUES 1 AND RAPHAEL HYPOLITO 2

1Programa de Pós-graduação em Hidrogeologia, Instituto de Geociências – USP, São Paulo, SP.

2Departamento de Geologia Sedimentar e Ambiental, Instituto de Geociências – USP, São Paulo, SP.

Presented by ANTONIO C. ROCHA-CAMPOS

In order to understand the mechanisms of contamination by metals, it is necessary to know the ways in which they are bound to the different soil components since their mobility depends on this, as do the mitigation and remediation of contaminated areas.

By means of sequential extractions the hydrogeochemical behavior of metal ions in contaminated soils will be determined. This method selectively extracts metallic ions associated with different soil fractions through sequential utilization of reagents from the least to the most aggressive.

Of interest in this project are the exchangeable ions, bound to oxides/hydroxides of iron and manganese, to carbonates, to organic matter, and to residual binding fractions.

The sequential extraction procedure for determination of heavy metals and their speciation in soils have been developed in the past 20 years. This methodology was introduced by Tessier et al. (1979) and later publications are largely based in this work.

In most of the literature references, the conditions under which the extractions were performed are not completely specified. Also, depending on the soil type and the metals analyzed, the extractions may present difficulties which have to be overcome.

In this study, the selective extraction methods will be chosen, those which are most interesting will be tested, and new methods will be developed.

An experimental station will be built for collecting soil and water samples, monitoring wells and carrying out experiments. In situ monitoring of parameters such as pH, Eh, CE, temperature and alkalinity will also be performed.

This project will contribute to our understanding about important mechanisms of mobility and fixation of metallic ions associated with soils. — (December 14, 2001).

Publication Dates

  • Publication in this collection
    09 Oct 2002
  • Date of issue
    Sept 2002
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