# Polychlorinated Biphenyls in the Snow Cover of South-Eastern Kazakhstan
## 3 Results
### Pollution of Snow Cover by Polychlorinated Biphenlys in Almaty Agglomeration (2018-2020)
In total, seven individual PCB congeners were registered. Light congeners 44 and 49, which belong to the homologous group of tetrachloropiphenyls, were dominant. The relative share of PCB 44 congener in the urban area ranged from 35 to 53% (Figure 7). The most toxic congener PCB 114 was present in the SC of the Northern bypass road in an amount of 33%. According to studies in this field, the content of POP compounds in precipitation is influenced by two main types of pollution sources: local sources and global transport [32]. The predominance of low-chlorinated congeners (dichloropiphenyls and trichloropiphenyls) in the composition of PCBs indicates the long-range transport of toxicants to the sampling area [59; 60; 61]. The dominance in the total concentration of PCBs of congeners belonging to the homologous group of tetra-, penta-, and hexachloropiphenyls indicates a similar composition of the detected PCBs with the composition of the main mixture \"Sovol\", which was used in the Soviet Union [50]. Therefore, this indicates the participation of mainly local or regional pollution sources in the sampling area for  
Figure 7: Relative content of PCB congeners in the snow cover of Almaty city in 2020.  
forming PCB composition. The coverage of the territory including a large number of snow sampling points allowed us to study the toxicants' distribution in characteristic zones, i.e., urban, mountainous, and flat areas, with different anthropogenic loads to reach a relatively detailed conclusion. Pollution of Snow Cover by Polychlorinated Biphenyls in the Territory of Iii River Delta and Iii-Balkhash State Natural Reserve (2021)  
The objects of the study in 2021 were the delta of the Iii River and the territory of the State Nature Reserve \"GNR Iii-Balkhash\", with a total area of 415 thousand hectares, situated in south-eastern Kazakhstan. The reserve is located in the ancient delta of Iii River and the southern Balkhash Lake region (Figure 8). The study aimed to obtain scientific data on the level of SC contamination by PCBs in this vast and important natural area, which had not been previously studied regarding this issue. According to the obtained data, it should be noted that PCBs were registered in the SC of all sampling points. The total concentration of PCB in the SC of the Iii River Delta was in the range of 0.088-0.397 \(\mathrm{\SIUnitSymbolMicro\text{$\mu$}}\)/L. At the points located in the  
Figure 8: Delta of Iii River and the territory of “Ili-Balkhash Lake” reserve (authors [PERSON], [PERSON]). zone, the content of toxicants in snow water reached 4.750 and 20.71 \(\upmu\)g/L. Such a high concentration of PCB, according to our studies, was not registered on the northern slope of the Ili Alatau Mountains or in the territory of the Almaty agglomeration. The average concentration of PCB in the SC of the entire study area, excluding two samples with a high content of the toxicant, was 0.227 \(\upmu\)g/L. In the upper part of the Ili River Delta, there were areas with higher values of the total concentration of PCBs. The largest number of congeners (seven) from all the taken samples, including strictly controlled \"marker\" (PCB 153) and highly toxic dioxin-like (PCB 105) congeners, were found here. Twenty-five PCB congeners in total were registered in the SC of this study area. In certain samples, their number varied from 1 to 7. A more frequent presence in snow water is typical for light congeners PCB 44 (53%) and PCB 97 (82%), which are included in the homologous groups of tetra- and pentachlorophenyls. The relative proportion of the founded PCB isomers was between 6% and 12%. In the snow samples of the study area, the more toxic PCB congeners were \"marker\" PCB congeners 52, 138, 153, and dioxin-like PCB 105 and 114. The congeners of the first group were founded in SC with concentration ranges of 0.027 \(\upmu\)g/L to 0.082 \(\upmu\)g/L, while dioxin-like ones were found in concentration ranges of 0.058 to 0.068 \(\upmu\)g/L.