# An Assessment of the Impact of Gypsum Deposit Development on Changes in the Radiation Environment
## 2 Materials and Methods  
### Study Area  
The study area is located in the northern taiga zone on a rolling plain formed over several ice ages. At the end of the last glaciation, huge volumes of meltwater seeped through soluble rocks and formed a karst relief with a large number of sinkholes, streams, lakes, caves and other karst formations. The soil cover depends on the composition of the underlying rocks and the degree of their drainage. Illuvial-ferruginous and alluvial-humus-ferruginous podzols are confined to moraine sandy-clavey deposits with a thickness of about 2-10 m and develop in well-drained areas of the relief--the tops of moraine hills and moderately steep slopes under bilberry--green moss spruce forests. In meso-depressions, where the thickness of the Quaternary deposits can reach 30 m, peaty-podzolic-gley soils are widespread. Unique soils with coarse, weakly and moderately decomposed litter and purely gypsum mineral horizons are developed at the gypsum outcrops on the surface [24].  
Sedimentary deposits of the Sakmarian stage of the Lower Permian (P1s) lie under the cover of the Quaternary deposits. The upper part of the sedimentary layer, 80 m thick, is composed of gypsum and anhydrite containing lenses and interlayers of dolomites and sandstones (Figure 1). Admixture of terrigenous material is noted everywhere, both in the groundmass and along cracks. Deeper lies a 140 m layer of limestones and dolomites of the Sakmarian and Asselian (P1a) stages of the Lower Permian [8].  
Groundwater is confined to the fractured and karstified zone in the upper part of the gypsum strata. It has a Ca-SO4 composition and total dissolved solids (TDS) of 2.3 g L\({}^{-1}\), corresponding to full saturation with respect to gypsum. Two rivers, the Pozera and the Chuga, 24 and 34 km long, respectively, flow in the immediate vicinity of the mining allotment of the deposit. The Pozera River, 24 km long, originates from a swamp massif and has low total mineralization values in the source area, which is explained by its predominant snow and rain feeding. Six kilometers downstream, TDS increases from 0.5 to 1.8 g L\({}^{-1}\) due to a consistent increase in underground recharge. In the longer Chuga River, TDS at the quarry latitude reaches 2.3 g L\({}^{-1}\); i.e., it is completely formed due to the dissolution of gypsum.  
Two lakes, Sennoe and Karasevoye, are moraine lakes with virtually no underground recharge. Their water has a Ca-HCO3-SO4 composition and minimal TDS values (0.1 g L\({}^{-1}\)). Three small unnamed lakes with difficult underground recharge, due to partial colmatation of the bottom, are classified as karst and have intermediate TDS values (0.8-1.8 g L\({}^{-1}\)). Quarry waters and waters from the quarry water settling tank have a Ca-SO4 composition. The TDS value in quarry waters was increased compared with groundwater to 2.6 g L  
Figure 1: A quarry at a gypsum deposit with a dump of overburden sandy–clayey rocks of Quaternary age.  
due to additional enrichment with calcium sulfates and sodium chlorides. In the quarry water settling tank, the TDS value corresponded to groundwater (2.3 g L\({}^{-1}\)).