A comprehensive radiological investigation of soils and water resources in artisanal gold mining areas in Ghana: Mining activities vs radiological risks

Global mining activity has intensely increased in response to the rise in gold demand and prices over the last two decades. Mining has been recognized as a potential source of radioactive exposure in the environment. Investigations of natural radionuclides, radon activity concentration and radon exhalation rates in soils, and in surface and groundwater resources were carried out in some gold mining areas in Ghana. Activity concentrations of Ra-226, Ra-228, Th-232, and K-40 in soil and water samples were analyzed with High Purity Germanium gamma ray detector while radon activity concentration and radon exhalation rates in soils were determined with passive radon detectors (CR-39) and exhalation chambers. The data obtained from the radioactivity measurement indicated that soils in the studied regions had high Th-232 activity concentrations as compared to Ra-226. Activity concentrations and radon exhalation rates were observed to be high in soils from farming areas and mining sites than in residential and undisturbed areas. Surface and ground water resources recorded elevated levels of the measured radionuclides above world average values of 0.1 Bq/l for Ra-226 and 1.0 Bq/l for Ra-228. Groundwater sampled from areas with close proximity to mining sites recorded higher radioactivity concentrations. This could be attributed to artisanal mining activities leading to leaching and seepage of radionuclides into bedrocks, aquifers and nearby water resources as well as miners directly washing gold ores and mining equipment in surface water bodies. The evaluated radiological risks associated with the ingestion and inhalation of radionuclides due to mining were found to be high particularly for the water resources. Therefore, the studies showed that the extraction, transportation, and processing of gold minerals, as well as the use of mine residues directly exposes miners and the populace to ionizing radiation and consequently posing radiological risks.