Abstract
The common ice plant (Mesembryanthemum crystallinum L.) is a widely studied model due to its tolerance to numerous biotic and abiotic stresses. In this study, carried out in model pots, the plants were treated with variant doses of Cd(II) and Cr(VI) and proved resistant to extreme levels of these heavy metals. Initial toxicity symptoms were observed upon final concentrations of 818 mg Cd kg−1 soil d.w., and 1699 mg Cr kg−1 applied as potassium chromate. Biometric analyses revealed that none of the Cr(VI) doses affected dry weight of the plant organs thus maintaining the shoot-to-root ratio. The Cd and Cr hypertolerance strategies were divergent and resulted in different accumulation patterns. For the case of Cd(II), an excluder-like mechanism was developed to prevent the plant from toxicity. For chromate, high accumulation potential together with Cr(VI) root-to-shoot translocation at sublethal concentrations was revealed (up to 6152 mg Cr kg−1 shoot at 4248 mg Cr kg−1 soil). It is concluded that M. crystallinum reveals considerable phytoremediation capabilities due to unique growth potential in contaminated substrates and is suitable for bioreclamation of degraded soils. The plant is especially applicable for efficient phytoextraction of chromate-contamination, whereas for Cd-affected areas it may have a phytostabilizing effect.
Highlights
The environmental impact of progressing anthropogenic activity brings severe risk to the bioand geosphere
Mesembryanthemum crystallinum tolerance to the presence of the two tested heavy metals was first evaluated based on the morphological visible symptoms
Neither plant growth nor shoot and root morphologies were disturbed by the presence of Cr(VI) administered up to the final doses of 2.3 mmol Cr per pot (1086 mg Cr kg−1 soil d.w.)
Summary
The environmental impact of progressing anthropogenic activity brings severe risk to the bioand geosphere. Among the main factors contributing to land degradation and deterioration are rapid industrial development, poor spatial planning, excessive exploitation of resources together with imbalanced water and soil management related to improper agricultural use. According to recent estimates, degraded soils contribute up to 24% of the global land area Soil degradation results from numerous processes that negatively influence critical properties of soil environment such as chemical, physical characteristics and biological activity. Among the dominant factors responsible for industrial soil degradation are chemical pollutants which include. Plants 2020, 9, 1230 both recalcitrant organic compounds (xenobiotics) and inorganic contaminants. The latter group covers a very divergent list of substances, namely acidic and alkali chemicals, salts, biogenic elements causing eutrophication, and, in particular, heavy metals, metallo-organic and inorganic complexes and derivatives
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