## 4 Results and Discussion
### Mutational Changes of Crucian Carp from the Tailings Pond
#### 4.2.2 Elemental Composition of Crucian Carp Organs  
In crucian carp organs, some elements are distributed selectively (Figure 5). The concentration of Ca, Sr, and Al in the gills of fish from the background reservoir (Chany Lake) is much higher than their concentration in other organs. Aluminum serves no known biological function and is both toxic to aquatic life and bioaccumulative [52]. The accumulation of these elements in the gills can be associated with the entry of a thin suspension of carbonate and clay minerals from the water. Iron is contrasted; the main organ of its concentration is the heart. In a smaller amount, it is contained in the kidneys and gills, and the muscles and gonads contain iron an order of magnitude lower. Additionally, elevated concentrations of Fe and Mn can cause neurological, genotoxic, pulmonary, and brain disorders in fish [53; 54]. Zinc and copper are distributed more evenly across organs. It has been noticed that prolonged exposure to Cu can evoke an acclimation response, allowing fish  
Figure 3: Linear dimensions of _Carassius auratus_ at the age of 5+ from Komsomsolsk pond. not only to survive but also withstand further exposure to higher concentrations. However, there are reproductive impairments, reduced growth, and behavioral changes [55]. Figure 4: The growth rate of crucian carp in the studied reservoirs in terms of weight and body length (light circles—fish from Chany Lake, black—from Komsomolsk pond). Figure 5: Distribution of elements in organs of _Canssius gibelio_ from Chany Lake (background reservoir). Lead, just like calcium, strontium, and aluminum, predominantly accumulates in the gills. The concentrations of metalloids (As, Sb, and Se) are very close in all organs, varying within (\(\upmu\)g/g dry weight) 0.13-0.34 (As), 0.00052-0.0089 (Sb), 0.38-1.4 (Se). It should be noted that the content of Pb, Cd, Hg, and Sb in gonads is significantly lower than in other organs. In the organs of crucial carp from Komsomsolsk pond, an increase in many elements is determined compared to the background (Figure 6). Antimony accumulated the most: in the heart I\({}_{\mathrm{conc}}\)F was more than 10,000, in all other organs--more than 1000. Recall that in the water of Komsomsolsk pond, the greatest value of I\({}_{\mathrm{conc}}\)W is determined precisely for antimony--350. Other metalloids and metals also accumulated in significant amounts. The I\({}_{\mathrm{conc}}\)F (As) was more than 100 in the gills, heart, liver, and kidneys (the concentration of arsenic in the pond water is 40 times higher than the background reservoir). According to [56], the bioaccumulation of As in the muscular tissue of _P. linetatus_ seems to be linked to its detritivorous feeding behavior, where this element is accumulated via ingestion of sediments with As high concentrations. A high positive correlation (r = 0.98) between the composition of the pond water and the level of element accumulation in organs was found. At the same time, the assimilation of some elements occur in different ways. For example, I\({}_{\mathrm{conc}}\)W(Cu) in the pond water was 1.6 and I\({}_{\mathrm{conc}}\)F(Cu) in organs was 1.4 (muscle) to 16 times (liver). Meanwhile, higher concentrations of zinc in water (I\({}_{\mathrm{conc}}\)W(Zn) = 3.8) were much lower in organs; the muscles and kidneys contained zinc lower than the background values, the liver was at the same level as in the background crucian carp, and the other organs had insignificant concentrations (1.2 (cavitar)--2.3 (heart)). The I\({}_{\mathrm{conc}}\)W(Pb) was 2.5. However, lead accumulated rather more in organs; the I\({}_{\mathrm{conc}}\)F(Pb) varies from 9.1 (gills) up to 250 (heart). It should be especially focused on the mercury accumulation. Despite the fact that its content in the water of Komsomsolsk pond and the background lake was low (!0.01 \(\upmu\)g/L), there was an intensive accumulation of mercury in the crucian carp organs from the pond; the largest value of I\({}_{\mathrm{conc}}\)F(Hg) was determined in the kidneys (420) and liver (100).