INFLUENCE OF ABIOTIC AND BIOTIC FACTORS ON SAMPLES OF D16 ALUMINUM ALLOY IN THE MIXING AREA OF SEA AND RIVER WATERS

In order to assess the corrosion resistance of samples of aluminum alloy grade D16, full-scale bench tests were carried out at two stations in the Don River mouth area. Test period: December 2018 – December 2019. During the research, the hydrological and hydrochemical regimes of the water area were described. Fluctuations of the ionic composition in the areas of the experiment depended on the volume of river runoff, the frequency and amplitude of surges and the associated intrusions of saline waters during surges or a drop in the water level during surges. It is shown that environmental conditions affect the experimental plates both directly and indirectly through the influence on the composition and structure of the forming fouling community. The dynamics of microphytoperiphyton on samples D16 in different parts of the delta was characterized by a two-peak curve with a maximum at the nineth month after the beginning of the experiment. Diatoms predominated, which is typical of many water bodies. Microzooperiphyton on the experimental plates is represented mainly by ciliates. With an increase in the exposure period, there was a tendency to an increase in the proportion of colonial and large sessile ciliates. The formation of macro-fouling communities began on samples that have been in the water for more than three months. The dominating species on the plates exposed at full immersion for 6 months were bryozoans Fredericella sultana. After 9 and 12 months the mollusks Dreissena polymorpha were dominant. When testing samples in water for 12 months, it was revealed that the largest area of corrosion damage for alloy D16 was obtained at Station 2 – 50 %, while during tests at Station 1 the area of corrosion damage does not exceed 30 % of the surface. According to the results of determining the composition of corrosion products on all plates, oxidation products of the samples surface, elements that make up the aqueous medium, and also elements of organic origin prevail.

D16 aluminum alloy, corrosion, Don River estuary, water mixing zone, hydroclimatic conditions, fouling communities