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Radioactivity
Published in Pradyot Patnaik, Handbook of Environmental Analysis, 2017
This method measures the total radium-226 in the water that includes both the dissolved isotope of this element and that present in the suspended particles. In this method, the radium is measured as its daughter isotope radon-222 resulting from the alpha decay. Radium is separated from water by coprecipitation with barium as sulfate (radium–barium sulfate) using acidified barium chloride solution followed by sulfuric acid. The mixture is stirred vigorously. The precipitate is filtered through a membrane filter and washed with dilute H2SO4. The filter is placed in a platinum dish or crucible, and treated with a small quantity of 48% hydrofluoric acid and a few drops of 10% ammonium sulfate solution and evaporated to dryness for the removal of silicates if present and decompose any insoluble radium compounds. The residue is ignited over a small flame to char the filter and burn off the carbon and then treated with 1 mL 85% phosphoric acid and heated over a hot plate first at 200°C and then at 400°C for 30 min. The precipitate fuses into a clear melt. Fuming with phosphoric acid removes the sulfite (SO32−). The mixture is then cooled and treated with 6 N HCl, and heated to dissolve radium completely. The solution is diluted with distilled water. The solution is placed in a bubbler, closed, and stored for several days to measure the ingrowth of radon. The bubbler is connected to an evacuation system. The liquid is aerated to purge out the radon gas. Radon may alternatively be purged with helium or nitrogen. It is then dried over a desiccant and collected in a counting chamber. Radon-222 is counted on an alpha scintillation counter. Details of the concentration techniques, scintillation counter assembly, and the radon bubblers are described in the method and the instrument manuals. Calculate radium-226 in the bubbler from the following equation, taking the correction, ingrowth, and decay factors into account: Radium-226,pCi=[(Rs−Rb)/Rc](C/AB) where Rs is the counting rate of sample per hour (cph), measured in the counting cellRb is the background counting rate, cph in the scintillation cell with the counting gas
Assessment of radiation dose from radon ingestion and inhalation in commercially bottled drinking water and its annual effective dose in Eastern Province, Saudi Arabia
Published in International Journal of Environmental Health Research, 2019
The study was conducted during the summer and autumn of 2016 at the laboratories of the department of Radiological Sciences, College of applied Medical Sciences University of Dammam. A total of 77 samples of drinking water sources; 47 bottled drink water and 27 tap water samples including 3 samples from water storage tank supplier were collected and examined. The bottled drink water samples were purchased from local supermarket and were chosen in order to represent water resources from different locations. The samples were stored in sealed bottles for more than four weeks in order to extinguish the radon diluted in the sample that originates from extraction at geological locations. After this time, radon will reaches the secular equilibrium and any radon presents in water sample is associated with diluted radium compounds. Hence, the radon activity can be measured and the activity concentration of diluted radium compounds can be evaluated.