# Polychlorinated Biphenyls in the Snow Cover of South-Eastern Kazakhstan
## 3 Results
### Pollution of Snow Cover by Polychlorinated Biphenlys in Almaty Agglomeration (2018-2020)  
From 2018 to 2020, the object of the study of PCBs in the SC was the territory of the Almaty agglomeration (AA), created in 2016 within the south-eastern part of Kazakhstan. The AA covers the northern slope of the Iii Alatau Mountains up to an altitude of 2755 m above sea level and a foothill plain with a minimum altitude of 487 m above sea level. There are many rivers of different water content. Tributaries of the Iii River, which is one of the main transboundary rivers in Kazakhstan, feed the unique Balkhash Lake. The territory of AA includes the near-dam part of the water area of the Kapshagay Reservoir that was built on the Iii River. The analysis of the results obtained over the years primarily shows the distribution of PCBs in SC in the whole AA, except for cases of their temporary absence at certain sampling points (Table 3). In 2018, the highest concentrations of the toxicants in the SC of the AA exceeding 0.1 ug/L, i.e., 100 pg/L, were noted at nine points during the first survey, and four points during the second survey out of 22 studied sampling points. The maximum PCB accumulation level was recorded during the second survey in the snow water of a mountain point (mountain skiing sports base (MSSB) \"Shymbulak\"), located at the altitude of 2755 m above sea level (1.942 ug/L) and at the area of Shamalgan Station  
Figure 4: Relative content of PCB congeners in solid precipitations in the territory of Almaty city. with an amount of 1.283 \(\upmu\)g/L. In total, 22 individual PCB congeners were registered in the snow samples. It is known that the presence of several congeners in SC samples is an indicator of the presence of various sources of PCB air pollution in an area. Many researchers came to this conclusion by studying the soil cover in cities [57; 58]. These conclusions are also confirmed by our studies [48]. Strictly controlled \"marker\" (indicator) PCB congeners 101 and 138, as well as PCB congeners 118, belonging to the group of highly toxic dioxin-like congeners, were registered in a wide range of PCB congener compositions in the snow samples taken at the indicated points. The \"marker\" congener PCB 52 and dioxin-like congener PCB 118 were also found in the SC of Almaty city. Highly toxic congeners were not found in the SC of the mountain zone. The concentrations of PCBs in the SC of small towns and urban-type settlements varied in a wide range from zero to 1.283 \(\upmu\)g/L. The highest values of the average content of PCBs (0.129 and 0.225 \(\upmu\)g/L) were registered in the SC of this zone. The maximum values of the relative content of PCB congeners in SC were noted for PCB 44 and 155; \"marker\" congeners PCB 52 and 138 were registered in the amount of 100 and 15%, respectively, as well as dioxin-like PCB 118 (39%). These isomers were present in the SC of Talgar and Kapshagay cities. In the snow water of small settlements, the content of PCBs reached 0.192 and 0.205 \(\upmu\)g/L. The dominant position in relative concentration had light congeners PCB 44 (up to 97 and 100%) and PCB 49 (up to 77%) and also PCB 151 (from 64 to 100%). The only case of the presence of dioxin-like congener PCB 118 was noted at the point close to the territory of Almaty city. Based on the 2019 results, we note a relatively low level of agglomeration SC contamination from the studied pollutants. The maximum concentrations of PCBs in the SC of certain points in the territory of Almaty and small towns were 0.140 and 0.148 \(\upmu\)g/L during the first survey and 0.039 and 0.044 \(\upmu\)g/L during the second. A decrease in the level of SC pollution by PCBs in 2019, compared with the data received in 2018, can presumably be explained by the fact that the winter of 2019 in the studied region was characterized by little snow and frequent thaws. As a result, fresh precipitation which was less exposed to the influence of local sources of pollution was taken for analysis.