Biotransformation fate and sustainable mitigation of a potentially toxic element of mercury from environmental matrices

The deposition of potentially toxic mercury (Hg) in various ecosystems and subsequent entry into the food chain pose serious concerns to the ecosystem, biodiversity, and public health. In terms of toxicity, Hg is considered as a neurotoxin and capable to augment in food chains and bind to the thiol functional entity in living tissue. Moreover, methylated mercury (CH3Hg+) is a highly toxic form of mercury and extremely difficult to remove from living bodies. Mercury methylation is mainly conducted by microbial and/or chemical processes under appropriate conditions. The mechanisms associated with mercury methylation inside the environment, their sources, production/degradation rate, and transport into the living organisms are not well understood. In addition, efficient and sustainable remediation strategies are essential to employ for mercury removal. Therefore, this review signifies a possible mechanism for mercury methylation and its transportation in the environment, including molecular mechanisms and genes associated with microbial-mediated mercury methylation, and identifies the gaps in existing research. The transport of Hg into the human body and associated health risks are given with suitable examples. Moreover, the escalating anthropogenic activities, the rate-limiting factors, and the sustainable remediation strategies implemented for mercury removal from the environment are discussed. This study will provide a scientific base, direction, and progress in future studies.