Preliminary Assessment of Mercury and Methyl Mercury Contamination of Sediments, Water and Fish from the Bétaré-oya Gold Extraction Site (Cameroon)

Abstract

The gold extraction process by mercury amalgamation is recognized worldwide as a process presenting an environmental and health risk linked to mercury contamination of the geo and biosphere close to the gold panning site. The aim of this work is to assess the risk of contamination by mercury of populations living in the locality of Bétaré-oya, which is subject to the phenomenon of small-scale artisanal mining. In order to achieve this, a small social survey was carried out on two gold extraction sites in the locality of Bétaré-oya. Samples of sediment, water and fish were also taken from these sites. After characterization, these samples underwent the total mercury was determined by an automatic mercury analyzer. Moreover, the methyl mercury was extracted from the samples and analyzed by inductively coupled plasma mass spectrometer coupled to gas chromatography and by gas chromatography coupled to an electron capture detector. The results obtained showed total mercury concentrations varying from 386 to 5072 µg/kg in sediments and from 24.6 to 8451 ng/L in water. Methyl mercury was measured at concentrations ranging from 7.62 to 165 µg/kg in sediments, from 2.54 to 15 µg/L and from 45.4 to 90.8 µg/kg in fish. Well water (15.0 ± 2.4 µg/L of methyl mercury) which is consumed by the populations of the study site, and fish contaminated with an average concentration of 68 µg/kg of Methyl mercury, represent the main vectors of the risk of direct contamination of the populations of the locality of Bétaré-oya by this pollutant.