Μetal Uptake by Sunflower (Helianthus annuus) Irrigated with Water Polluted with Chromium and Nickel

Vasiliki Stoikou,Marios Kostakis,Sotiris Stasinos,Ioannis Zabetakis,Nikolaos Thomaidis,Vangelis Andrianos,Sofia Attiti

doi:10.3390/foods6070051

Abstract

The water aquifers of the regions of Asopos River in Viotia and Messapia in Evia (Greece) have been contaminated with hexavalent chromium (Cr (VI)) and bivalent nickel (Ni (II)). Given that these areas are the two biggest tuber producing regions of Greece, in our previous work, the cross-contamination of the food chain with these two heavy metals was quantified. In the present study, the potential of sunflower (Helianthus annuus) cultivation in these regions is evaluated. The scope of our study was to investigate the uptake of chromium and nickel by sunflower, in a greenhouse experiment. The study included two cultivation periods of plants in six irrigation lines with different levels of Cr (VI) and Ni (II) ranging from 0 μg/L (control) to 10,000 μg/L. In all plant parts, statistically significant increased levels of Cr (VI) and Ni (II) were found when compared to control ones. Also, a positive correlation, both for Cr and Ni, between levels of heavy metals in irrigation water and plants was observed. Following European Food Safety Authority recommendations, the obtained oil was evaluated as safe for consumption, therefore, sunflower cultivation could be a valid bioremediation solution for the Asopos and Messapia regions.

Highlights

Asopos River in Viotia and Messapia in Evia are the two main tuber producing regions in Greece
The maximum absorption of Cr was observed in the 5000 μg/L irrigation line (14.76 × 102 μg/g dry matter) (Supplementary Materials Figure S1). This could be explained on the basis that the highest levels of heavy metals in water may have caused minor phytotoxic effects to the plants that reduced the absorption of heavy metals
0 μg/L and 1000 μg/L, 5000 μg/L, and 10,000 μg/L. Given that both Cr and Ni tend to have an identical tendency to be phytoaccumulated, with the highest percentage concentrating in the roots [33], we have demonstrated here the ability of sunflower to phytoaccumulate significant amounts of these toxic metals

Summary

Introduction

Asopos River in Viotia and Messapia in Evia are the two main tuber (i.e., carrot, potato, and onion) producing regions in Greece. In a greenhouse experiment simulating the irrigation parameters of these regions, it was found that both Cr and Ni (present in irrigation water) can cross-contaminate the food tubers [1]. This cross-contamination affects the nutritional value of food products [2]. Phytoextraction is a remediation green technology that uses plants to remove, reduce, degrade, or immobilize heavy metals from polluted soil and water. Water pollution with heavy metals has been a worldwide concern, as it poses great threats to crop production causing significant cross-contamination of the food chain [4], resulting in negative impacts on human health [5]

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