## 2 Materials and Methods  
### Study Area and Sampling  
The Lisava uranium mining sector is located about 5 km south Ciudanovita, in the western margin of the Anina Mountain part of the Banat Mountains (southwestern Romania). In the area of interest (45\({}^{\circ}\)06\({}^{\prime}\)20\({}^{\prime\prime}\) N; 21\({}^{\circ}\)03\({}^{\prime}\)33\({}^{\prime\prime}\) E), the exploration and mining of uranium ore was undertaken using galleries from the Dobrei North, Dobrei South and Dobrei East deposits. Mining activities were stopped in 1999, and the area has been partly rehabilitated [17]. The perimeter included the Lisava tailing dump, formed from the tailings deposited from the mines mentioned above, and the zone where ore was picked up and transported to the processing plant (Figure 1). From a geological perspective, the Lisava sector belongs to the west Banat region in the southern Carpathians and is part of the Alpine orogenic belt. The regional lithost stratigraphic formations are, from the oldest to the newest: a Proterozoic layer, represented by crystalline  
Figure 1: **(A)** Geological map of the study area (extracted from a geological map of Romania at a 1:200,000 scale [18]; **(B)** sampling area of the Lisava uranium mining sector. schists, followed by Carboniferous formations consisting of grey conglomerate layers, sandy layers and organic-rich black shales, sandstone and siltstone [19]. Overlying the Carboniferous layer are Permian formations made up of the Lower Permian (sandstone, siltstone and shale) and Upper Permian (Ciudanovita Series) that hosts uranium deposits, comprising conglomerate, bituminous sandstone, sandstone, siltstone and carbonaceous shale deposited in five cycles. The uppermost formations are Jurassic layers composed of grey limestones and marls lying over conglomerates, as shown in Figure 1A. The Ciudanovita sedimentation cycle has 30-40 m thick hosted uranium deposits in the western and eastern flank of the Natra-Girliste Anticline (Figure 2). The Ciudanovita Series have five sequences in the eastern part of the Natra-Girliste Anticline. Each rhythm is between 20 and 200 m thick and begins from the bottom to the top with conglomerate, ending with fine-grained facies, which are predominantly siltstone. Three out of the five cycles contain uranium, and every cycle comprises cross-bedded microconglomerates, gritstone, sandstone and bituminous siltstone of an alluvial and lacustrine-alluvial origin. Intercalated with uraniferous-bearing cycles, barren rocks represented by well-sorted conglomerate and sandstone derived from extrusive igneous rock occur [19; 20; 21]. The dump material is a mixture of sterile rock and fragments of mineralized rock represented by red sandstones and reddish or grey microconglomerates that incorporate uneconomic small amounts of uranium. The waste deposit is compacted and covered by a layer of surface soil overgrown with vegetation that has grown spontaneously on the entire surface of the waste dump, which is more developed in the western part of the dump. The soil samples were collected from 47 sampling points that were uniformly distributed over the whole surface of the Lisava uranium mining sector. The sampling point locations are presented in Figure 1B. Soil sampling was conducted by manually boring holes with a diameter of 55 mm drilling at a depth range of 0-15 cm. At each point, five samples were collected from the corners and center of a square with ten-meter sides. The permanent grass cover was excluded. After collection, the samples were mixed, resulting in one composite sample weighing about 1.5 kg, and placed into a plastic bag. Together with the soil samples, three mineralized rock samples from the dump material were collected. The rock samples were selected based on dose rate measurements in air using a radiation survey meter (Berthold 137 UMO 137). The samples collected were red sandstones (Figure 3).