Assessment of Mercury Contamination from Gold Mining Operations in Zamfara State Using Chemical Analysis

Artisanal and small-scale gold mining in Zamfara State, North West Nigeria, employs mercury amalgamation as the primary gold recovery technique, releasing significant quantities of mercury into the surrounding environment. This study assessed the extent of mercury contamination in soil, water, and biological samples from mining-affected communities in Anka, Maru, and Birnin Magaji Local Government Areas, and evaluated the public health implications of observed contamination levels. Soil and sediment samples were collected from mining sites and from residential zones at progressive distances from active operations. Water samples were drawn from streams and community wells. Hair and urine samples were collected from mining workers and non-worker community members as biomonitoring matrices. Mercury was determined by cold vapour atomic absorption spectrophotometry. Soil mercury concentrations at active mining sites reached 48 mg/kg, far exceeding the Dutch target value of 0.3 mg/kg for residential land. Stream sediment mercury was 12 to 84 mg/kg. Drinking water sources showed mercury levels up to 8.4 micrograms per litre, compared to the WHO guideline of 1 microgram per litre. Urinary mercury in miners was 38 to 284 micrograms per gram creatinine, indicating chronic exposure above occupational threshold limit values. Neurological symptom prevalence questionnaires showed elevated reporting of tremors, fatigue, and memory complaints among highly exposed miners. These findings confirm a serious mercury contamination crisis requiring immediate public health intervention, mercury-free gold processing technology adoption, and medical screening of affected communities.

Keywords: mercury contamination, artisanal gold mining, Zamfara State, biomonitoring, public health