Mercury (Hg) Contamination From Artisanal Gold Mining: Environmental Risks, Health Impacts, Effluent Limits, and Adsorption-Based Remediations

Abstract

Mercury (Hg) levels, ubiquitously occurring in nature, can be exacerbated by anthropogenic activities. The elevated Hg environmental levels posed a risk to public and ecological health. After a half-century of the Minamata disease, recent investigations have continuously revealed the Hg neurodegenerative effects on humans. This review mainly examined artisanal and small-scale gold mining (ASGM) elevating Hg environmental levels. A United Nations investigation identified the top 10 countries significantly using Hg for ASGM, with Indonesia heading the list. The Hg effluent standards of leading countries were reviewed, finding 5.0 μg/L as the most recurring. Moreover, elevated Hg levels in the environment have been reported from other underdeveloped regions, feasibly involving socio-economic aspects. The adsorption technique stood out among the investigations treating actual ASGM effluent. Although highly engineered adsorbents have higher capacity and efficiency, valorized agricultural wastes into activated carbons are deemed more practical and sustainable for regions depending on ASGM. The review further elaborated on critical operational conditions for adsorption and models for Hg removal. The identified research gaps include the limitation of real, practical, and industrial-scale applications of the current adsorption techniques. Likewise, the Hg adsorption mechanism in literature appeared to have a theoretical gap, which may require further exploration. This article is categorized under: Science of Water > Water Quality Engineering Water > Water, Health, and Sanitation Engineering Water > Sustainable Engineering of Water.