The Use of Sequential Extraction Procedures for the Characterization and Management of Contaminated Soils

Abstract

Metal mobility and availability in solid samples, such as soils, sediments and sludges, is frequently studied with sequential extraction procedures, which allow to partition the total metal content into classes of different reactivity. From the experimental point of view, each extraction step requires many practical operations, which can represent sources of error if they are not properly executed. The first part of the paper gives indication on how to perform sequential extractions, from sample pretreatment to extract analysis, in order to reduce experimental errors. The second part describes the main applications of sequential extraction schemes for the characterization and management of contaminated soils: the assessment of the risks associated to metal pollution, the evaluation of the feasibility and efficiency of remediation techniques, the study of soil properties and of metal behaviour and plant availability.

Is there a future for sequential chemical extraction?

“…63 The review of Young et al 64 is recommended for providing a clear introduction to the development of sequential extractions, some of the limitations such as lack of specificity and some of the recent innovations for improving the procedure. Other reviews have included an overview of the use of leaching/extraction tests for risk assessment of trace metals in contaminated soils and sediments, 65 the use of sequential extraction procedures for the characterization and management of contaminated soils, 66 the fractionation of metals in atmospheric aerosols 67 and recent methodological advances, in particular for on-line dynamic fractionation. 68 An ongoing limitation to the use of sequential extraction has been the availability of only a few reference materials for checking the performance of methods and laboratories.…”

Heavy metals mobilization from harbour sediments using EDTA and citric acid as chelating agents

“…Since metal extraction effectiveness depends on the binding form of the element of interest, preliminary sequential extraction using the Tessier's method [25][26][27][28] were performed to investigate their distribution into five fractions: exchangeable, bound to carbonate, bound to Fe-Mn oxides and hydroxides, bound to organic matter and residual.…”

Monitoring of total and bioavailable heavy metals concentration in agricultural soils

“…Sequential extraction methods, although originally developed for use on sediments, have been extended to soils (Tessier et al 1979;Ure et al 1993;Garcia et al 1996;Sahuquillo et al 1999;Abollino et al 2002Abollino et al , 2005Elass et al 2004;Mu-Hua et al 2005). However, although they are useful for assessing the relative importance of the different forms of metals (exchangeable, bound to carbonates, bound to iron and manganese oxides, bound to organic matter and residues), they have several limitations: they are rather laborious, can be sources of errors if not properly carried out, and not have been unreservedly accepted by the scientific community because the results are seldom comparable and depend on the analytical conditions used.…”