Content of heavy metals in tsyogorychk fishery of Dnipropetrovsk region
Authors:   Oles Honchar Dnipro National University, Korzhenevska P. O. , Sharamok T. S. ,   Oles Honchar Dnipro National University, Marenkov O. N. ,   Oles Honchar Dnipro National University
Published: May 2021

In modern conditions, the problem of pollution of reservoirs with heavy metals becomes especially relevant, especially given the man-made load on surface waters of Ukraine. Heavy metals are among the most dangerous conservative chemical pollutants, due to their physiological and biochemical characteristics of action, as well as transmission through food chains. Also, the danger of heavy metals is that they are bioavailable and enter the fish ponds not only during the water harvest, but also during the application of fertilizers to fields or feeding fish. Fish that complete the trophic chain of the reservoir are the end products of the fishery activities of the enterprise and directly accumulate heavy metals. At the same time, such heavy metals as Fe, Zn, Mn are essential, ie they in physiological concentrations are vital for the implementation of regulatory functions in fish. However, the body of fish accumulates heavy metals that even in small concentrations adversely affect its physiological state. The aim of the study was to determine the characteristics of the accumulation of heavy metals in the body of young carp fish in typical pond farms of Dnipropetrovsk region. The object of research were this year's scaly carp and silver carp, which were grown in Tarom and Krynychany fisheries. In the cities of heavy metals in water ponds and the carcass of fish were determined by atomic absorption spectrophotometer her on a spectrophotometer S115-M1. The results of the study show that the content of Pb and Fe in the water of ponds of both fisheries did not exceed the MPC (SOU, 2006). The Cd content in the water of the Krynychany fish farm exceeded the maximum concentration limit by 2 times. The level of Mn in the water of the Tarom fish farm was 3 times higher than the MPC. The level of Zn content in both fish farms exceeded the permissible concentrations by almost 3 times. The concentration of Cu exceeded the MPC in the water of the ponds of the Tarom fish farm 5 times, and Krynychansky - 14 times. It is known that lead with significant exposure can cause bleeding in the digestive tract of fish, anemia, liver and kidney damage. In Tarom fishery, the maximum content of lead was found in scaly carp, which is 41,7% more than in white carp. A similar trend was observed in the Krynychany fish farm, but the content of this element in carp was only 2,2% higher. At the same time, the lead content of carp of the scaly Tarom farm was 34,4% higher in comparison with the same-age carp individuals grown in the Krynychany fish farm. The lead content in the body of young carp fish of the Dnieper fisheries was low. Cadmium is known to be more toxic than other heavy metals. In the young of silver carp Tarom fish farm cadmium concentration was higher by 14,3% than in carp. In fish of the Krynychany farm, on the contrary, the cadmium content was higher by 14.3% in scaly carp compared to silver carp. The biological role of manganese in fish is realized mainly through enzymes that are activated by this element. In Tarom farm the highest content of manganese was observed in silver carp, the concentration of manganese in scaly carp was 2,2 times less. In the Krynychany fish farm, on the other hand, the manganese content of scaly carp is 35% less than that of silver carp. Analyzing the data, it can be noted that the concentration of manganese in fish of Krynychany fish farm was higher compared to Tarom in 3,2 and 1,1 times in carp and silver carp, respectively. Copper is required for the synthesis of erythrocytes, in addition, it is part of liver proteins and a number of oxidative enzymes. In the young fish of both fish farms, the maximum copper content was observed in carp, it exceeded the content of this metal in silver carp by 1,3 and 2,1 times in Tarom and Krynychany farms, respectively. At the same time, the concentration of copper in this year's Tarom farm exceeded this indicator in the fish of the Krynychany fish farm by 1,5 and 2,3 times for carp and silver carp, respectively. The biological role of iron is mainly related to the function of iron-containing proteins. In young fish of Tarom fishery, the maximum concentration of iron ions was observed in silver carp and was 47,8% higher compared to carp. In the Krynychany fishery, on the other hand, a larger amount of iron was concentrated in the carp's body and was 1.9 times higher than in the silver carp of the same reservoir. The highest level of iron among the same-age fish of both fish farms was found in the young silverfish of Tarom farm, which was 2,4 times higher than the level of iron in silverfish of Krynychany fishery. The iron content in the young scaly carp of the Tarom fish farm was 21,5% higher than in the carp of the Krynychany farm. The importance of zinc for the body of fish is due to its participation in the regulation of many metabolic components in zinc-containing enzymes. In Tarom fish farm the highest content of zinc was found in carp, which is 2,4 times more than in silver carp. In Krynychany fish farm the highest concentration of zinc was found in silver carp, it was 18,6% higher than the concentration of zinc in carp. The highest level of zinc content among the studied fish farms was observed in the scaly carp of the Tarom farm and was 2,4 times higher than in the same carp of the Krynychany fish farm. The content of zinc in the carcass of silver carp of the Krynychany farm was higher by 19,6% in comparison with the one-year-old individuals of the Tarom fish farm. Thus, in the body of young fish of the studied fish farms actively accumulated such essential elements as Fe and Zn, which are necessary for normal growth and development of the organism. The minimum content of heavy metals was set for Cd. This pattern is the norm for growing fish. Prospects for further research are related to the study of the effect of toxicants of different origins on the morphobiological parameters of carp fish, which determines the feasibility of their continuation with the use of fish of different ages raised in the Dnipropetrovsk region. In addition, the results obtained can contribute to effective scientific support for the development of aquaculture in the region.