Study of Cyanide Contamination of Market Garden and Agricultural Products Grown Around the Samira Gold Mine (Niger)

Abstract

The term cyanide refers to all the compounds producing the ─C≡N group. It comes from both anthropogenic and natural origins. Its presence in the environment is largely related to gold mining. Cyanide is very scary because of its toxicity causing very deadly environmental consequences. The objective of this work is to study the fate of cyanide and assess its contamination on the environment in the vicinity of a potential source of pollution such as a gold mine. In this study, soils and foods samples from the Samira gold mine and its surroundings in southwestern Niger were collected, analysed and compared with equivalent control samples grown in areas free of any industrial cyanide source. Total cyanide contents in the soils of the Samira site and its surroundings are 2 to 104 times higher than the Canadian standard (0.90 µg g^-1 CN^-) for agricultural soils, while the control soils are almost free of cyanide. These results show a migration of cyanide from the mine tailings to the surrounding area and these soils are unsuitable for any crop. The produced foods on these polluted soils have total cyanide contents 2 to 5 times higher than their controls. These contaminated matrices reveal negative impacts of the Samira mine's gold activities on its immediate environment. Ingestion of these foods would lead to serious health consequences for local populations.