Activation of Non‐Enzymatic Antioxidants by Lepidium sativum L. Exposed to Hg During Assisted Phytoextraction

Abstract

This study focuses on the physiological response of Lepidium sativum L. to Hg and/or nitrilotriacetic acid (NTA) during soil reclamation. Greenhouse experiments are conducted in soil contaminated with Hg to final concentrations of 10 or 100 mg kg−1. The influence of Hg and NTA is studied on the growth of L. sativum L. and the activation of its non‐enzymatic antioxidant system, including generation of ascorbic acid (AA) and tocopherols (TOCs). The results shows that Hg is accumulated by L. sativum L. in its aboveground tissues, but increased lipid peroxidation and H2O2 formation in the plant shoots, which is a symptom of oxidative stress. Plants exposed to Hg produced increasing amounts of AA and TOCs to protect their cells from oxidative damage. Application of NTA to polluted soil did not show any toxic effects on L. sativum L. growth or physiological processes. Amendment of polluted soil with NTA significantly increased Hg accumulation in the aerial tissues of L. sativum L., resulting in decreased soil contamination. The use of NTA can therefore be considered for use in assisted phytoextraction of Hg contaminated soil.

The influence of compost and nitrilotriacetic acid on mercury phytoextraction by Lepidium sativum L.

“…In accordance with Zhang et al (2002) hyperaccumulating plants are those that have a BF > 1 . Low BF values obtained for plants harvested from contaminated soil confirm the earlier findings that L. sativum L. is a non‐hyperaccumulator . Nevertheless, the slight transfer of Hg to aerial tissues was noticed.…”

“…Mercury concentrations in plant samples and soil or growing medium samples were provided in accordance with the procedure described in Smolinska and Bonikowski . The concentrations of Hg in plant tissues and soil or growing medium were used to calculate the efficiency of phytoextraction: Bioaccumulation factor (BF) was calculated using (Eqn (1)): …”

“…57 The previous study of Smolinska and Bonikowski showed that the application of NTA as an enhancement in phytoextraction did not show toxic effect on L. sativum L. and effectively increased Hg accumulation in aboveground plant tissues. 30 Due to high costs of this chemical reagent, the present investigation was provided with the use of half-lower concentration of NTA than in the previous work.…”

“…31 Low BF values obtained for plants harvested from contaminated soil confirm the earlier findings that L. sativum L. is a non-hyperaccumulator. 30 Nevertheless, the slight transfer of Hg to aerial tissues was noticed. TF obtained for plants cultivated in polluted soil at Hg final concentration of 10 mg kg −1 dry weight was at the same level as obtained by Liu et al for Opuntia stricta exposed to low Hg concentration (2 μL L −1 ).…”