Accumulation of radioiodine from aqueous solution by hydroponically cultivated sunflower (Helianthus annuus L.)

doi:10.1016/j.envexpbot.2005.05.014

Environmental and Experimental Botany

Volume 57, Issue 3, October 2006, Pages 220-225

https://doi.org/10.1016/j.envexpbot.2005.05.014 Get rights and content

Abstract

The suitability of sunflower plants (Helianthus annuus L.) for the phytoremediation of soils and waters contaminated with radioactive iodine was tested following the ¹²⁵I uptake from a hydroponic medium and translocation during 32-day cultivation. The plants accumulated about 26% of the applied activity in case of combination of ¹²⁵I (1.3 MBq) and 0.1 mM K¹²⁷I (“carrier ¹²⁵I”) and 47% when only ¹²⁵I (1.3 MBq, “non-carrier ¹²⁵I”) was added. When hydroponic medium was changed for the fresh one every 4 days, the plants accumulated up to 59% of starting activity of non-carrier ¹²⁵I. The ¹²⁵I distribution within the plant was followed using autoradiography. At low iodine level (non-carrier ¹²⁵I) the radionuclide was localized mainly in the roots. At high iodine concentrations (carrier ¹²⁵I) it was found mainly in the upper part of sunflower plants. All iodine removed from the liquid medium was found in the plant body. Volatilization of iodine (in the form of I⁰ or volatile organic compounds) apparently did not occur during accumulation and translocation. The achieved results indicate that sunflower can be used for phytoremediation of radioactive iodine, even if it is not its hyperaccumulator.

Introduction

Over the last 15 years, phytoremediation, i.e. the use of plant biotechnology for the removal of organic pollutants and toxic metals from contaminated sites and wastewaters, has become an area of intense research. Phytoremediation now appears as a promising option for clean-up of the environment. Its main advantages include low input and environmentally friendly character. With the development of risk assessment approaches to environmental contamination, it is clear that in many situations a slow, sure, green in situ strategy may be the most optimal variant. Phytoremediation is expected to be particularly useful for the in situ extraction of toxic metals from contaminated sites (Vaněk and Schwitzguébel, 2003, Nriago and Pacyna, 1988).

The inevitable prerequisite of successful application and commercialization of phytoremediation is the choice of suitable plants based on the understanding of the mechanisms and limiting factors controlling the uptake and translocation of the pollutants in plants.

One of the severe contaminants is radioactive iodine (¹²⁵I). The accident at the Chernobyl nuclear power plant released massive quantities of radioiodine into the atmosphere (Aurengo et al., 1998, Robbins and Schneider, 1998). Radioactive iodine isotopes have been also generated as fission and decay products from the nuclear fuel and from uranium impurities on the surface of the fuel rods. Tichler and Norden (1982) reported that in 1988 about 36 GBq of radioiodine were emitted by nuclear power plants with pressurized water reactors (PWR) and about 89 GBq by nuclear power plants with boiling water reactors (BWR). The effects of radionuclides on the functioning of the ecosystems vary considerably and have economic and public health significance.

Soils contaminated with radionuclides pose a long-term radiation hazard to human health through exposure via the food chain and other pathways. While a great deal is known about the relationship between internal radiation exposure and thyroid cancer, much less is known about the oncogenic effects of internal radiation exposure from iodine isotopes.

Iodine is an essential element for mammals including humans. However, it was not proved indispensable for plants. Nevertheless, in some plants (e.g. seaweed from the Phaeophyceae genus) iodine exists in the form of organic compounds, such as 3,5-di-iodine tyrosine (Hou et al., 1997, Muramatsu et al., 1995). Halophytes such as Allenrolfea occidentalis are capable of facultative or obligatory growth on arid soils and can contain a high level of iodine (Trent et al., 1997).

In this contribution, the accumulation and translocation of ¹²⁵I and/or ¹²⁷I by the sunflower Helianthus annuus L. has been analyzed with the aim to find out whether this plant species can be utilized efficiently for phytoremediation of iodine contaminated soil and waters. The sunflower was chosen as a model system due to its high biomass production, easy hydroponic cultivation and possible utilization for rhizofiltration (Dushenkov et al., 1999). Additional advantage is the availability of agrotechnique necessary for large-scale application. The hydroponic cultivation in sterile conditions was used in order to quantify iodine uptake in a model system avoiding the potential influence of microorganisms as well as the soil effects.

Section snippets

Plant material

Hydroponically cultivated sunflower plants (H. annuus L.) had been pre-cultivated for 4 weeks in a flowerpot. Then single plants were placed into Erlenmeyer flasks with 300 mL of hydroponic medium. Plants were kept at 20 °C with a 16 h period of light. The hydroponic medium contained 3.4 mM Ca(NO₃)₂, 2.5 mM KNO₃, 2 mM (NH₄)₂SO₄, 1.8 mM KH₂PO₄ and 1 mM MgSO₄, pH 5.

Growth value calculation

Growth value (GV) was calculated from the ratio between m(x) − m(0) and m(0), where m(0) is fresh weight of plant at the start of the

The effect of iodine concentration on the sunflower growth and radionuclide accumulation

The effect of iodine concentration on the biomass production was followed using non-radioactive ¹²⁷I (in the form of KI). The highest KI concentration, which can be tolerated by H. annuus was 0.1 mM (GV = 0.172, Fig. 2). In order to check, whether sunflower plants are equally sensitive to radioactive nuclide (¹²⁵I) as to the non-radioactive one (¹²⁷I), the impact of 0.1 mM K¹²⁷I and of the mixture of 0.1 mM K¹²⁷I and K¹²⁵I (carrier ¹²⁵I) on sunflower growth was compared. No significant differences

Discussion

The aim of this study has been to evaluate the suitability of sunflower for remediation of soils and waters contaminated with radioactive iodine (¹²⁵I). Our findings of concentration range, which can be tolerated by sunflower plants, correspond to the data obtained on rice (Oryza sativa) with iodide and iodate published by Mackowiak and Grossl (1999).

Similarity of the behaviour of radioactive and non-radioactive nuclides was proved by comparison of the effects of non-radioactive iodine and a

Acknowledgements

This work was supported by COST Project No. 859.10. The authors thank Mrs. Z. Hornychová and Mrs. J. Brychnáčová for their technical assistance. The authors are grateful to Dr. L. Hauzerová for his final linguistic revision of the English text.

References (16)

T. Bannai et al.
Levels of radionuclides in plant samples collected around the uranium conversion facility following the criticality accident in Tokai-mura
J. Environ. Radioact.
(2000)
X. Hou et al.
Determination of chemical species of iodine in some seaweeds (I)
Sci. Total Environ.
(1997)
Y. Muramatsu et al.
Volatilization of methyl iodine from the soil-plant system
Atmospheric Environ.
(1995)
J. Robbins et al.
Radioiodine-induced thyroid cancer: studies in the aftermath of the accident at Chernobyl
Trends Endocrinol. Metab.
(1998)
S.C. Sheppard et al.
Is the akagare phenomenon important to iodine uptake by wild rice (Zizania aquatica)?
J. Environ. Radioact.
(1997)
P. Soudek et al.
Laboratory analyses of ¹³⁷Cs phytoremediation
Chemosphere
(2004)
A.M. Zayed et al.
Selenium volatilisation in roots and shoots: effects of shoot removal and sulphate level
J. Plant Physiol.
(1994)
A. Aurengo et al.
Management of 29 children with thyroid cancer following the Chernobyl accident
Bull. Acad. Natl. Med.
(1998)

There are more references available in the full text version of this article.

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Environmental and Experimental Botany

Abstract

Introduction

Section snippets

Plant material

Growth value calculation

The effect of iodine concentration on the sunflower growth and radionuclide accumulation

Discussion

Acknowledgements

References (16)

Levels of radionuclides in plant samples collected around the uranium conversion facility following the criticality accident in Tokai-mura

J. Environ. Radioact.

Determination of chemical species of iodine in some seaweeds (I)

Sci. Total Environ.

Volatilization of methyl iodine from the soil-plant system

Atmospheric Environ.

Radioiodine-induced thyroid cancer: studies in the aftermath of the accident at Chernobyl

Trends Endocrinol. Metab.

Is the akagare phenomenon important to iodine uptake by wild rice (Zizania aquatica)?

J. Environ. Radioact.

Laboratory analyses of ¹³⁷Cs phytoremediation

Chemosphere

Selenium volatilisation in roots and shoots: effects of shoot removal and sulphate level

J. Plant Physiol.

Management of 29 children with thyroid cancer following the Chernobyl accident

Bull. Acad. Natl. Med.

Cited by (31)

Emerging paradigms into bioremediation approaches for nuclear contaminant removal: From challenge to solution

A review of iodine in plants with biofortification: Uptake, accumulation, transportation, function, and toxicity

A strategy for bioremediation of nuclear contaminants in the environment

Bioremediation and bioeconomy potential of sunflower (Helianthus annuus L.)

Transport and disposal of radioactive wastes in nuclear industry

Phytoremediation of radionuclides in soil, sediments and water