Radon Concentration in the Water of the Ex-tin Mine Pond and Its Adjacent Groundwater

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Radon (²²²Rn) is a ubiquitous radioactive gas that comes from the decay of ²²⁶Ra as part of the ²³⁸U decay chain, one of the naturally occurring radioactive materials (NORM). Radon, radium, and uranium are soluble in water and can be found in various concentrations in groundwater. Human activity, such as mining, can elevate NORM in the environment. Additionally, by-products of tin smelting (tin-slag) that contain high concentrations of NORM might leach radon and ²²⁶Ra into the groundwater. This study aims to investigate the radon concentration in the water found in the tinmine area of Sungai Liat and Pangkal Pinang, Bangka Island, Indonesia. Six surface water samples were collected from the ex-tin mine pond, and twenty groundwater samples were collected from the nearby well. For each, 10 mL of water sample were injected into 10 ml of mineral oil scintillator inside a 20-mL glass vial. The integral counting method by portable liquid scintillation counter (Triathler, Hidex) was used to measure the radon concentrations in the samples. The radon concentrations in the ex-tin mine ponds ranged from 31 Bq L^-1 to 75 Bq L^-1. The measured radon concentration in the wells ranged from 48 Bq L^-1 to 129 Bq L^-1. The highest and second highest radon concentration in groundwater were found in the sample closest to a tin-slag storage and ex-tin mine pond, respectively.