# Polychlorinated Biphenyls in the Snow Cover of South-Eastern Kazakhstan
## 3 Results
### Pollution of Snow Cover by Polychlorinated Biphenlys in Almaty Agglomeration (2018-2020)
The indicator congener PCB 101 (0.017 \(\upmu\)g/L) and dioxin-like congener PCB 114 (0.038 \(\upmu\)g/L) were registered in the SC of two points in the urban area. In the SC of Almaty city, which is the center of the agglomeration, we detected the dominance of the highly toxic dioxin-like isomer PCB 114 at 53% (Figure 5). \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline  & \multicolumn{4}{c}{**PCB Congeners**} & \multicolumn{4}{c}{**PCB Concentration, \(\upmu\)g/L**} \\ \cline{2-9}
**Zone** & **2018** & **2019** & **2020** & \multicolumn{4}{c}{**2018**} & \multicolumn{4}{c}{**2019**} \\ \cline{3-9}  & **2018** & **2019** & **2020** & \multicolumn{4}{c}{**1 ***} & **2 *** & **1 *** & **2 *** & **2020** \\ \hline
1. Mountain territory & 40; 42; 44; 49; 151 & 40; 42; 48; 86 & 44; 49 & 0.031 & 1.942 & 0.026 & 0.0 & 0.005 (0.038) \\ \hline
2. Territory of Almaty city & 41; 44; 49; 52; 66; 95; 87/115; 101; 118; 119; 138; 151 & 40; 41; 44; 74; 114; 137 & 0.066 & 0.058 & 0.044 & 0.009 & 0.071 \\ \hline
3. Small towns and urban-type settlements & 40; 44; 49; 52; 85; 97; 110; 118; 119; 128; 138; 151; 155 & 42; 44; 74; 86 & 44; 66/95; 74; 97 & 0.129 & 0.225 & 0.039 & 0.016 & 0.207 \\ \hline
4. Small settlements & 40; 44; 49; 97; 118; 121; 151 & 42; 44; 86 & 44; 48; 49; 74; 97 & 0.093 & 0.028 & 0.016 & 0.007 & 0.068 \\ \hline \hline \end{tabular} Note.* = number of field trips for sampling: AA = Almaty agglomeration.  
\end{table} 
Table 3: Average content and congener composition of PCBs in snow cover of the Almaty agglomeration in 2018–2020. The PCB concentration distribution in the SC of the entire territory of the AA in 2020 (Figure 5) showed that PCBs were registered in the SC at 27 out of 41 sampling points. Out of seven points chosen in 2020 in the mountainous area, PCBs of 0.038 \(\upmu\)g/L were found only in the snow of the ski resort \"Shymbulak\" (Figure 6). Such relatively high concentrations can be attributed to the fact that the ski resort \"Shymbulak\" is situated closer to the territory of Almaty city compared to the other sampling points, which are situated at a considerable distance in the east and south  
Figure 5: Relative content of PCB congeners in the SC of Almaty territory. Figure 6: Content of PCBs in the snow cover of Almaty agglomeration (AA) depending on the altitude. west directions from the ski resort. Consequently, convective air flow from the mountain valley circulation raises polluted aerosols above the city to the ski resort altitude and to the higher layers of the atmosphere. At the same time, solid precipitation in this zone accumulates a certain part of the pollutants, including PCBs. As shown in Table 3, the average PCB content in the SC of Almaty city in 2020 was 0.071 \(\upmu\)g/L. This was the highest average concentration of PCBs (0.207 \(\upmu\)g/L), which turned out to be a characteristic of the SC of small towns and urban-type settlements zones. The highest content reached 0.209, 0.447, and 0.492 \(\upmu\)g/L in the SC of Boraldai village, Talgar city, and Uzynagash village, respectively (Figure 6). Pollution sources of the SC of these settlements resulted from emissions from industrial facilities and from the Central Heating and Power Plant Number 2 located close to Boraldai village. PCBs were registered in the SC of 16 small settlements (SS) out of 22 surveyed. Their highest concentrations were in the SC of Ulan village (0.396 \(\upmu\)g/L). The average toxicant content indicators in the SC of this zone (0.068 \(\upmu\)g/L) were approximately equal to those of the territory of Almaty city in 2020. Possible pollution sources of the SC of this zone include the production facilities of small- and medium-sized businesses, autonomous utilities often operating on high-ash coal (up to 40%), and railway and coal handling facilities. The atmospheric transport of pollutants from the territory of nearby cities such as Almaty and others is not excluded. In 2020, PCB congener composition in the AA did not differ significantly from that observed in 2019.