Monitoring of the main parameters of pond water in order to obtain safe products for joint cultivation of sturgeon and carp fish

Abstract

The article presents the results of studying the hydrochemical regimes of carp ponds in polyculture and for the introduction of sterlet (Acipenser ruthenus) into polyculture. The highest pH values were in pond 2, and in the second half of June and the first half of July exceeded the upper limit of normal (norm 6.5–8.5) by 0.3 and 0.5, respectively. In July, the upper limit of the norm was exceeded in the water of pond 1, by 0.1 and 0.2, respectively. From August, the pH of water increased in both ponds until October and in pond 2 the active reaction of water was higher, compared to pond 1, 5.08.2020, by 18.3 %, 20.08.2020 by 12.3 %, 5.09.2020, by 3.8 %, 20.09.20 and 5.10.20, respectively by 2.5 and 2.4 %. Higher in pond 2, compared with pond 1, was the permanganate oxidation of water in all studied periods, but the largest difference was 5.07.2020 and amounted to 6.9 mg O/l. In the second half of July, permanganate oxidation of water was the lowest, but was at the upper limit of normal, then in August increased sharply and was highest in October – 26.3 mg O/l in the pond 1 and 26.5 mg O/l in the pond 2. Dichromatic oxidation of water of the studied ponds was during the experiment in pond 2 slightly higher than normal and ranged from 50.5 (5.06.2020) to 57.9 (5.07.2020) mg O/l and only 20.07.2020 it was the lowest and was 34.2 mg O/l. In pond 1, the dichromate oxidation of water at the beginning of the experiment was 52 mg O/l, gradually decreased and 20.06.2020, was 46 mg O/l, in July, the chemical oxygen demand (COD) increased sharply to 63.6 and also decreased sharply up to 40.5 mg O/l. From 05.08.2020, COD rose by 27.8 % above normal, remained at approximately the same level during September and decreased to 62 mg O/l in early October. The content of free ammonia in the water during the whole period of fish farming exceeded the norm from 2.6 to 5 times, and the highest, except for 20.06.2020, it was in pond 2. The highest difference in ammonia content in the water of the studied ponds was 5.07.2020 and 5.10.2020, and was, respectively, 0.1 and 0.08 mg N/l. The content of ammonium nitrogen and mineral phosphorus in the water of the studied ponds exceeded the norm, and the nitrogen content of nitrates and nitrites was within the norm. In pond water, the concentration of Ca2+, Mg2+, Na+, CO32-, HCO3-, SO42-, Cl-did not exceed the norm. was 5.07.2020, and was 1.20 mg/dm³, which is higher than the norm by 20 %. The total hardness and mineralization of water in the studied ponds did not exceed the norm.