# An Assessment of the Impact of Gypsum Deposit Development on Changes in the Radiation Environment
## 2 Materials and Methods
### Sample Description and Preparation  
In August 2023, 14 water samples were collected to determine the activity of the uranium isotopes \({}^{234}\)U, \({}^{235}\)U and \({}^{238}\)U. Within a 3 km radius of the quarry (N 64\({}^{\circ}\)05\({}^{\prime}\)04\({}^{\prime\prime}\)-64\({}^{\circ}\)08\({}^{\prime}\)10\({}^{\prime\prime}\), E 42\({}^{\circ}\)33\({}^{\prime}\)21\({}^{\prime\prime}\)-42\({}^{\circ}\)41\({}^{\prime}\)40\({}^{\prime\prime}\)), samples were collected from two rivers, five lakes and one groundwater source. Samples of quarry water and water from a settling pond were also collected. Following the detection of high uranium concentrations in the quarry water, additional samples were collected from it in January and February 2025 (W-11-1 and W-11-2, respectively, in Table 1). Samples of 20 L were acidified with hydrochloric acid to pH 1-2, and the required amount of the isotopic tracer \({}^{232}\)U was added so that its activity was comparable with the activity of the isolated natural uranium isotopes. After 4 h, the pH was brought to 4.5-5.5 by using a 20% solution of hexamethylenetetramine (uroropine), verifying it with universal indicator paper. After about 1-2 h, 15 g of sorbent in the form of specially prepared activated carbon of the BAU-A brand was added to the sample under study and thoroughly mixed with a stirrer for 10 min, after which it was allowed to settle for 24 h. The water was drained with a hose, and the carbon with the remaining water was poured into 1.5 L plastic containers and transported to the laboratory.  
In August 2023, ten bottom sediment samples, fourteen soil samples, three gypsum samples and three samples of overburden moraine deposits were also collected to determine the activity of the uranium isotopes \({}^{234}\)U and \({}^{238}\)U, as well as \({}^{137}\)Cs, \({}^{226}\)Ra, \({}^{232}\)Th and \({}^{40}\)K. The sample mass was about 1 kg. Bottom sediment samples were collected by using a Peterson hand sampler at a distance of 0.5 m from the shore from silt deposits of the same two rivers and five lakes where water sampling was carried out. Soil samples were collected from the litter-peat soil horizon \"O\" with a thickness of 2-7 cm. This is a surface horizon consisting of organic material of varying degrees of decomposition (no more than 50%) and various botanical compositions. The organic matter content is >35% of the horizon mass. It is underlain by a clay-illuvial soil horizon \"B1\" with a thickness of 5-15 cm [25]. Samples of gypsum and overburden moraine loans were collected directly on the territory of the quarry.  
Figure 2a shows the study area and sampling locations.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**ID**} & \multirow{2}{*}{**Water Point**} & \multirow{2}{*}{**N**} & \multirow{2}{*}{**E**} & \multicolumn{2}{c}{**2*U**} & \multicolumn{2}{c}{**2*U**} & \multicolumn{2}{c}{**2*U**} & \multicolumn{2}{c}{**2*U**/**2*U**} & \multicolumn{1}{c}{**U**} \\  & & & **(mBq L\({}^{-1}\))** & **(mBq L\({}^{-1}\))** & **(mBq L\({}^{-1}\))** & **(mBq L\({}^{-1}\))** & **(mBq L\({}^{-1}\))** & **(mBq L\({}^{-1}\))** \\ \hline W-1 & Poarea River 1 ** & 64.089 & 42.635 & 3.04 \(\pm\) 0.46 & 3.14 \(\pm\) 0.47 & -0.38 & 1.03 \(\pm\) 0.15 & 0.25 \(\