Real and simulated bioavailability of lead in contaminated and uncontaminated soils.

Marin Senila

doi:10.1186/2052-336x-12-108

Abstract

BackgroundLead (Pb) is a toxic element that occurs in elevated concentrations in soils, mostly as a result of anthropogenic activities. This study assess the Pb bioavailability in soils from two areas with different contamination level using Diffusive Gradients in Thin-Films (DGT) technique, single extractions and metal contents of vegetables grown on contaminated soils.ResultsIn the area situated far from mining and smelting activities, the pseudo total Pb concentration (12 – 51 mg kg−1 dw) was found to be comparable to that normally found in unpolluted areas. In the area from the vicinity of the Pb smelter very high concentrations of pseudo-total Pb (850 – 9300 mg kg−1 dw) were found. The average concentrations of Pb accumulated in onion, garlic, carrot, and parsley grown on this contaminated soils were 18, 48, 38 and 91 mg kg−1 dw, respectively, and represent a risk factor for the consumers.ConclusionsThe present study demonstrates the utility of DGT technique for the assessment of Pb bioavailability, since, generally, better correlations are obtained between the effective Pb concentration and Pb concentration in vegetables than for bioavailable Pb determined by chemical extractions and Pb concentration in vegetables.

Highlights

Lead (Pb) is a toxic element that occurs in elevated concentrations in soils, mostly as a result of anthropogenic activities
The aims of this study were: (1) to evaluate the Pb bioavailability in soils with different contamination levels in NW Romania using chemical extractions, Diffusive Gradients in Thin-Films (DGT) technique and vegetables Pb content and; (2) to evaluate the capacity of chemical extractions and DGT to accurately predict Pb bioavailability in contaminated and uncontaminated soils by studying the relationships between soil characteristics, real Pb bioavailability in soil assessed by bioaccumulation in plants and simulated Pb bioavailability assessed by DGT and chemical extractions
Positive correlations were found between Cation exchange capacity (CEC) and total organic carbon (TOC), both in contaminated and uncontaminated areas, which is usually observed in soils [10]

Summary

Introduction

Lead (Pb) is a toxic element that occurs in elevated concentrations in soils, mostly as a result of anthropogenic activities. For the assessment of a metal’s bioavailability in soils, various single or sequential extraction schemes, based on different chemical extractants (e.g. neutral salt solutions, diluted acids, complexing agents) were developed and applied [7,8,9,10]. By applying these techniques, neither the decrease in metal concentrations at the root-induced processes in the rhizosphere which influence the metal’s mobility and bioavailability [15,16]

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