226Ra In Trickling Waters From The Vicinity Of A Phosphogypsum Deposition Site

Phosphate rock is a raw material used during the production of phosphate fertilizers. As a waste by-product, phosphogypsum is characterized by technically enhanced natural radioactivity (NORM). During the production of phosphate fertilizers, most of the natural 238U from the phosphate ore ends up in the final products, while 80 percent of 226Ra is incorporated into phosphogypsum (CaSO₄ - 2H₂O). The phosphogypsum from one Croatian phosphate fertilizer factory is deposited at a local site situated at the borderline of Lonjsko Polje Nature Park, which implies that the constant monitoring of the deposition site environment is necessary. In this investigation, the activity concentration of 226Ra in trickling water samples from the surroundings of the mentioned deposition site was measured. The samples were collected by piezometers and after radiochemical separation of 226Ra measured with an alpha spectrometer. Activity concentrations of 226Ra in trickling water were within the range from 8 ± 4 Bq/m³ to 34 ± 9 Bq/m³ so we can conclude that layers of clay underneath the pile serve as good isolation. In addition, long-term systematic investigations showed a significant decrease in 226Ra activity concentrations in the trickling water. However, constant monitoring is necessary to detect possible future changes in the radioactivity levels in the environment. (author).