# Current State of the Gold Mining Waste from the Ores of the Ursk Deposit (Western Siberia, Russia)
## 1 Introduction  
Sulfide-containing mine tailings are a potential source of acid mine drainage (AMD) [1, 2, 3, 4] and gas emanations [5, 6]. Of particular interest are seasonal variations in the structure and composition of technogenic systems depending on environmental parameters in regions with a continental climate characterized by cold, long winters and short, warm summers. Frozen soils are a complex multiphase system, which, due to the inconstancy of temperature and pressure, are characterized by varying dynamics. At temperatures below 0 \({}^{\circ}\)C, there are sudden peaks in the electric potential at the pore water-ice interface, and the rates of some chemical reactions increase [7, 8, 6]. The most intense geochemical transformations are observed in the layer of seasonal temperature fluctuations, in which chemical leaching is activated, associated with rock cracking under the influence of expanding and freezing pore fluid [9]. Changes in natural conditions primarily concern surface watercourses near dumps. Suffide-containing waste is oxidized due to oxygen in the air and water; acidic sulfate flows are formed with total dissolved solids up to 10 g/L and high concentrations of a wide rangeof chemical elements: metals (Cu, Zn, Cd, Pb, Fe, and Be) and metalloids (As, Sb, and Se). In the areas adjacent to sulfide-containing dumps, landscape changes occur: acid erosion of soils, formation of cracks and gouges due to long-term impact of aggressive drainage, \"burned out\" roots of trees, and destroyed vegetation. Mechanical demolition of tailings along the slope occurs, and a taper is formed, in which water-saturated, dense acidic sands are located. Furthermore, a water stop is formed, due to which flows spread laterally, and, over time, technogenic changes cover more territories. It is also known that mine tailings exercise a thawing effect on the underlying soils and cause the formation of positive temperature anomalies [9], which, in the long term, leads to the degradation of permafrost rocks [10] and creates many problems (for example, the loss of the bearing capacity of engineering structures in areas of high anthropogenic pressure) [11]. This study aims to provide a comprehensive assessment of the current state of the abandoned waste dumps of gold-bearing ore mining and processing (Ursk settlement, Kemerovo region), the drainage valley, and the surface watercourses exposed to technogenic impact. An integrated approach is very promising for the study of such sites, since geochemical transformations of the mineral composition of waste can significantly affect the physical and chemical properties of soils and bedrock. For example, a set of methods is used to control the dumps of the ongoing production of Zn-Pb pores [12; 13]. The results of geophysical surveys, including the electrical resistivity tomography (ERT) and magnetometry, are confirmed by geochemical surveys. The ERT method is widely used to study the hydro-geological dynamics of dumps [13; 14; 15; 16]. Geophysical methods may be employed to trace the flooded areas and directions of water infiltration, as well as areas of pollution around the dump, including minerals redeposited by aeolian processes: authigenic or detrital. Many researchers emphasize the indispensability of geophysical methods for studying the internal structure of waste rock piles and migration of pollutants [17; 18; 19; 20; 21; 22; 23; 24]. Ursk dump, located in the village Ursk of the Kemerovo region (54.45\({}^{\circ}\) N, 85.4\({}^{\circ}\) E) containing barite-pyrite bulk material from the oxidation zone of the Novo-Urskoe pyrite deposit after gold extraction by cyanidation, was formed in the 1930s (Figures 1 and 2). A natural stream flows near its foot, becoming an acidic stream with high concentrations of dissolved metals. Figure 1: Location of the Ursk dump. The dashed lines indicate the natural fault zone according to [25].