Rhizospheric soil chromium toxicity and its remediation using plant hyperaccumulators

Abstract

The hyper-accumulation of chromium in its hexavalent form is treated as a hazardous soil pollutant at industrial and mining sites. Excessive accumulation of Cr⁶⁺ in soil threatens the environmental health and safety of living organisms. Out of two stable forms of chromium, Cr⁶⁺ is highly responsible for ecotoxicity. The expression of the high toxicity of Cr⁶⁺ at low concentrations in the soil environment indicates its lethality. It is usually released into the soil during various socio-economic activities. Sustainable remediation of Cr⁶⁺ contaminated soil is of utmost need and can be carried out by employing suitable plant hyperaccumulators. Alongside the plant’s ability to sequester toxic metals like Cr⁶⁺, the rhizospheric soil parameters play a significant role in this technique and are mostly overlooked. Here we review the application of a cost-effective and eco-friendly remediation technology at hyperaccumulators rhizosphere to minimize the Cr⁶⁺ led soil toxicity. The use of selected plant species along with effective rhizospheric activities has been suggested as a technique to reduce Cr⁶⁺ toxicity on soil and its associated biota. This soil rectification approach may prove to be sustainable and advantageous over other possible techniques. Further, it may open up new solutions for soil Cr⁶⁺ management at polluted sites.

NOVELTY STATEMENT

Phytoremediation is an eco-friendly technology that has been widely used for the treatment of Cr⁶⁺ contaminated soils. Most of the phytoremedial studies either focus on the ability of plant hyperaccumulators alone or in association with rhizospheric microbes for the successful remediation of Cr⁶⁺. The current study lays emphasis on different soil parameters and interactions (both biotic and abiotic) at the plant rhizosphere that is much essential for providing a sustainable remedial solution for Cr⁶⁺ contaminated soils.

Keywords:

• Environment
• Hexavalent chromium
• Hyperaccumulators
• Rhizosphere
• Toxicity

Acknowledgment

The author(s) acknowledge the infrastructural support provided by Siksha ‘O’ Anusandhan (Deemed to be University), Bhubaneswar, Odisha.

Authors’ contributions

All authors contributed to the study’s conception and design. Material preparation, data collection, and analysis were performed by Pratyush Kumar Das, Bidyut Prava Das, Bikash Kumar Das, and Patitapaban Dash. The first draft of the manuscript was written by Pratyush Kumar Das and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.

Conflict of  interests

The authors have no relevant financial or non-financial interests to disclose.