Understanding the holistic approach to plant-microbe remediation technologies for removing heavy metals and radionuclides from soil

Abstract

Heavy metals (HMs) and radionuclides are released through geological and anthropogenic activities and enter the environment through wastewater, soil and sediment. Large amounts of Pb (>1000 ppm), Zn (>4000 ppm) and Cd (40–400 ppm) have recently been reported in soils near Picher, USA. These inorganic pollutants cannot be degraded and cause damage to the vital human organs. Different industrial and municipal solid waste was a major source of HMs in soil, including airborne aerosols. In the same manner, nuclear waste and radioactive materials used (e.g., medical facilities) or released in different processes contribute to the environmental pollution of radionuclides. The release of such HMs ions from different sources leads to mutagenesis, carcinogenesis and poses serious risks to the living organisms. As a result, proper management of waste from these sources, as well as environmentally friendly remediation methods, is imperative. However, recent studies have shown that it is more difficult to remove HMs and radionuclides from the soil, but they can be effectively neutralized or converted into a less toxic metabolites. The combination of a unique plant-microbe system plays a key role in the remediation process. However, new bioremediation methods are now being used to eliminate HMs and radionuclides. Microbes are capable of bio-transforming, bio-sorbing and biomineralizing HMs and radionuclides through their inherent catabolic process. Enhancing phytoremediation using different strategies for the remediation of HMs and radionuclides is necessary to ensure that the land resource is safe, fertile and productive for sustainable use.

Keywords

• Heavy-metals
• Radionuclides
• Microbes enhanced phytoremediation
• Plant growth-promoting rhizobacteria ( PGPR)
• Sustainability
• Toxicity