# Polychlorinated Biphenyls in the Snow Cover of South-Eastern Kazakhstan
## 1 Introduction  
The SC analysis was carried out in the south-eastern region of Kazakhstan, which includes parts of the territories of three regions of the Republic of Kazakhstan (Almaty, Zhambyl, and Karaganda provinces) and occupies the northern slope of Ili-Alatau, including a vast foothill plain. The study area also includes the whole basin of the Ile (Ili) River with numerous tributaries. This south-eastern Kazakh region is densely populated and one of the largest and most economically significant territories in Kazakhstan. The total length of the Ili River is 1439 km; the first 624 km is situated in China, and the rest in Kazakhstan. The total area of the basin is 140.000 km\({}^{2}\), of which 77.400 km\({}^{2}\) belongs to Kazakhstan [1, 2]. The total runoff volume of the Ili River basin is 2287 km\({}^{3}\)/year, of which 174 km\({}^{3}\)/year is formed in China. Sixty kilometres from Almaty, the Kapshagai Reservoir was built at the Ili River, one of the largest artificial waterbodies in Central Asia. Its area is 1450 km\({}^{2}\), and the water volume is 16.0 km\({}^{3}\). Notably, 70% of the water inflow into the reservoir is from the Ili River. The left-side tributaries are the Shelek, Turgen, Esik, Kaskelen, and Talgar Rivers. Within the reservoir dam, the Kapshagai Hydro Power Plant (KHPP) was built with a capacity of 364 MW (rated capacity is 434 MW) [2]. The Ili River Delta is the largest natural inland delta of Central Asia (CA) with a total area of 20.000 km\({}^{2}\), of which 8000 km\({}^{2}\) belongs to the recent delta. The rest belongs to the ancient delta with branching channels (\"Bakanases\") [2]. Against the background of globally widespread desertification and the degradation of river deltas (deltas of the riversSyrdarya, Amudarya, Shu, etc.) [3], the area of the modern delta of II River is the only remaining river delta in Central Asia. The delta's area is included in the Ramsar convention and the list of wetlands of the international importance of the Convention on Wetlands of International Importance as waterforb habitat (adopted in the city of Ramsar, Iran) [4; 5]. In 2018, the IIi-Balkhash State Nature Reserve (SNR Iii-Balkhash) was created within the contact zone between the IIi Delta and Lake Balkhash. It has a protected reserve regime and it is a unique object in terms of ecological restoration. The Almaty agglomeration was created on this territory, including five cities. Almaty is the biggest city and the core of the agglomeration. The total land area of the agglomeration is 939.5 thousand hectares, and 188 settlements of the Almaty region are located in this agglomeration zone, with a total population of 2.5 million people. An agrarian-industrial complex has developed outside the urban areas. There are rather large irrigation areas: Akdala (30.000 hectares), Shengeldy (18.000 hectares), and Kerbulak (1400 hectares) [6; 7]. This vast territory is subject to significant anthropogenic impacts on transboundary and regional nature conditions. As a consequence, there is a need to study the ecological and toxicological effects of the natural conditions. Hence, this study's aim is to assess the level of environmental pollution of the snow cover in south-eastern Kazakhstan using the chromatographic determination of PCB content with a congener composition in the SC. This is because snow cover functions as a temporal storage medium for pollution inputs. Polychlorinated biphenyls (PCBs) are included in the list of persistent organic pollutants (POPs) which are recognized by the international community as substances that pose a great danger to people and the environment [8]. Even short-term human exposure to high levels of dioxins can lead to pathological changes to the skin, such as chloracne and focal darkening, as well as changes in liver function. Prolonged exposure damages the immune system, the emerging nervous system, the endocrine system, and reproductive function [8; 9].