Effect of chelating agents on phytoxicity and bioaccumulation of heavy metals in vascular plants

Miroslav Horník,Jana Marešová,Jana Guldanová,Martin Pipíška,Jozef Augustín

doi:10.36547/nbc.1136

Abstract

In this work the effect of chelating agents ethylenediaminetetraacetate (EDTA) and nitrilotriacetate (NTA) on phytotoxicity and bioaccumulation of Cd and Co in tobacco plants (Nicotiana tabacum L.) hydroponically grown in diluted Hoagland media (HM) spiked with 109Cd and 60Co was studied. Speciation analysis using a program Visual MINTEQ showed, that the portion of bioavailable ionic Me2+ forms significantly decreased in the presence of EDTA or NTA in 25% HM for account of [Me-EDTA]2- or [Me-NTA]- complexes. We found that the equimolar addition of EDTA or NTA to 50 μmol/dm3 CdCl2 or CoCl2 in HM positively diminished phytotoxicity of Cd or Co on tobacco plants. Bioaccumulation of Cd by tobacco roots during 8 d cultivation was minimally affected in the presence of equimolar concentrations of EDTA or NTA to 10 μmol/dm3 CdCl2 in media. On the contrary, equimolar concentration of EDTA or NTA added into HM caused considerable decrease of Co uptake by tobacco roots. Cadmium showed higher mobility in conductive tissues of tobacco plants than cobalt and the transport ratio in the presence of EDTA or NTA increased 2-times or 3-times in comparison with control experiments (without addition of chelates), respectively. In the case of cobalt this effect was observed in a less extent. Obtained data suggest the possibilities and constraints in the use of chelating agents in phytoextraction technologies in term of phytotoxicity, uptake and translocation of metals in plant tissues.

Highlights

Heavy metals soil pollution is a serious worldwide problem and can be potentially harmful to human health via the food chain
The aim of the current work was to investigate the influence of chelating agents ethylenediaminetetraacetic acid (EDTA) and nitrilotriacetic acid (NTA) on Cd and Co phytotoxicity and bioaccumulation in tissues of hydroponically cultivated tobacco plants (Nicotiana tabacum L.)
The high concentrations of EDTA and NTA used here likely mask the effects of the exudates from the roots

Summary

Introduction

Heavy metals soil pollution is a serious worldwide problem and can be potentially harmful to human health via the food chain. Metals soil contamination results from anthropogenic activities such as mining, smelting, fertilizer application, and in the case of radionuclides from typical operations of nuclear fuel cycle, nuclear weapon testing and occasional nuclear disasters. The stricter implementation of environmental laws urges the development of costeffective soil remediation methods. Traditional techniques of remediation are expensive and may cause secondary pollution. Phytoremediation, the use of green plants to remove pollutants from soil, is one cost-effective method to remediate metal and radionuclide contaminated soils. The technical aspects of phytoremediation are described in numbers of review papers (see latest works in this area e.g. PILONSMITS and LEDUC, 2009; VANGRONSVELD et al, 2009) and monographs The technical aspects of phytoremediation are described in numbers of review papers (see latest works in this area e.g. PILONSMITS and LEDUC, 2009; VANGRONSVELD et al, 2009) and monographs (see e.g. MACKOVA et al, 2006; WILLEY, 2007)

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