Emerging mercury and methylmercury contamination from new artisanal and small-scale gold mining along the Nile Valley, Egypt

Abstract

The past decade witnessed the initiation and boom of the Artisanal and Small-scale Gold Mining (ASGM) activities in the hyper-arid southern Egypt. The ores are mined in the Eastern Desert and then transported to the densely populated farming communities in the Nile Valley, where the river provides the water resources needed for ore processing. In search for economic benefits, the poorly educated farmers with limited technical resources transformed their cultivated lands into ASGM operations, exposing themselves, their families, the residents, and the Nile ecosystems to several environmental and occupational health problems. Using integrated remote sensing, field, geochemical, and isotopic analyses, we report the first inventory of ASGM-related total mercury (THg) and methylmercury (MeHg) levels in tailings, amalgamation-tailing ponds, and surface and groundwater with emphasis on the Edfu city and its surroundings. The field and remote sensing-based mapping of ASGM activities reveals clustering around the Nile waterways and suggests interaction of Hg contamination sources with their surrounding receptors. Common ASGM practices include release of contaminated water from unlined amalgamation-tailing ponds into irrigation and drainage canals, and spreading of tailings over cultivated soils. In a short period (10 years), the released Hg contaminated multiple media, including the surface water, the shallow and deep aquifers, and possibly the soil, crops, and livestock. THg levels in amalgamation-tailing ponds (1200–8470 ng/L) are fourfold higher than US EPA and eightfold the WHO thresholds. The contaminated waters released from amalgamation-tailing ponds raised THg levels in surface water (irrigation canals: 50–100 ng/L; drainage canals: THg: > 200 ng/L) and groundwater (shallow and deep aquifers: 80–500 ng/L). Our findings highlight the need to extend the adopted approach to cover the entire length of the Nile River and its valley and the importance of conducting awareness campaigns to educate residents and health care providers about potential ASGM-related environmental and health hazards. Graphical Abstract

Analysis of Mercury in Aquifers in Gold Mining Areas in the Ecuadorian Amazon and Its Associated Risk for Human Health

“…This relationship between Hg concentrations in surface and groundwater is evidence of the interaction between these two environments and may be related to infiltration processes that occur when Hg present in surface water bodies is mobilized to the aquifer [ 35 ]. These findings highlight the importance of determining the sources of aquifer recharge in order to identify potential sources of contamination that may be affecting the quality of groundwater resources [ 36 ].…”

Impact of mining on the livelihood of women in Gashaka local government area, Taraba State

“…Additionally, Ahmed et al (2021) examined the dynamics of artisanal gold mining in Gashaka Local Government Area of Taraba State, noting a lack of protective gear among miners. Abdelaal et al (2023) observed clustering of artisanal and small-scale gold mining activities around the Nile waterways in Egypt, emphasizing mercury contamination sources and their impact on surrounding receptors.…”

Environmental Stressors of Mozambique Soils Quality

“…A particular critical problem associated with the artisanal gold mining is the use of mercury in the final extraction step [11,12]. Liquid mercury is used for the amalgamation process, in which there is the separation of gold by the remaining components of the ores.…”

“…Moreover, there are some unsustainable and/or unregulated practices that may contribute with toxic pollutants release and/or soil degradation and, consequently, constitute stressors that may affect environmental quality. The release into environment of mercury from artisanal gold mining is a typical example of highly polluting activity [11,12]. Deforestation for illegal timber commerce [13], conversion of forest soil into crop cultures [14] and charcoal production [15], are examples of activities that degrade soil quality.…”