A review of the sidelined pollutant: Reviving the fight against heavy metal contamination in an era of emerging contaminants

Abstract

Groundwater contamination by heavy metals (HMs) remains a pressing global concern, presenting substantial risks to humans, animals, plants, and the environment. Although emerging pollutants have received increasing attention, the adverse impacts of HM have not been adequately resolved. This comprehensive review examines the current state of knowledge regarding HM in groundwater, addressing sources, global trends, transport, fate, sampling techniques, modeling, quality control, toxicity, treatment, sustainable measures, and vital research gaps. HM research has continued to dwindle since 2022, these chemicals infiltrate groundwater systems through various pathways, and their mobility and bioavailability are affected by changes in climate, geological heterogeneity, and chemical properties. Moreover, HM may interact with other emerging contaminants to enhance migration and toxicity; however, little or no research has been conducted to fully understand cocktail migration mechanisms and impacts in groundwater systems. Despite the existence of various treatment techniques, no single approach has been universally accepted as the sole solution for completely removing HM from drinking water systems. There is a pressing need for standardized and advanced sampling methods, stringent quality control measures, and the incorporation of cutting-edge technologies such as smart water sensors that can detect both charged and uncharged contaminants, and nanotechnology for effective management. The increasing toxicity of HM and their harmful effects on human health and ecosystems emphasize the need for continuous and novel research involving sustainable remedial strategies, as the battle against metal contamination in groundwater systems requires constant dedication, innovative research, and a shared commitment to protecting our environment.