From sources to solutions: integrated approaches for Cd, Hg, and Pb remediation- a comprehensive review

Abstract

Background

Urbanization, industrialization, and various other anthropogenic and natural activities increase the release of heavy metals (HMs) into the environment, posing a severe threat to nearby flora, fauna, and humans. HMs are toxic, non-biodegradable, silent, and subtle killers that alter the soil attributes and threaten plants, animals, and humans, impacting biodiversity and human health.

Objective

HMs such as Cd, Hg, and Pb disturb physiological processes in plants and animals, reducing growth, impaired reproduction, and negative impacts on human beings upon bioaccumulation in food chains. This results in the dire need for effective remediation strategies to clean up HMs in soil and water.

Methods

Various conventional and non-conventional approaches remove and detoxify HMs from the substrate. Metal immobilization, detoxification, and removal via microbial approaches, i.e., biosorption, bioaccumulation, bioaugmentation, bioleaching, and bio-volatilization, are effective in remediating Cd, Hg, and Pb.

Results

Additionally, microbes utilize direct and indirect mechanisms to help the remediation of Cd, Hg, and Pb from contaminated sites. Genetically engineered microbes (GEMs) are also being explored for the remediation of these metals from contaminated soil, offering both opportunities and challenges regarding associated risks and management practices. This review emphasizes the possible heavy metal sources responsible for increasing the concentration of HMs in the environment and their effect on plants and animals. We will discuss various conventional remediation strategies that can help remediate Cd, Hg, and Pb.

Conclusion

By elucidating the role of microbial-dependent remediation approaches, including GEMs, this review also contributes to advancing sustainable approaches for mitigating Cd, Hg, and Pb-contaminated soil and safeguarding environment.