Hydrocarbons in the water and bottom sediments of the North Crimean Canal and adjacent water areas (Crimea) during the change of the water regimen of the canal
O. V. SOLOVEVA, E. A. TIKHONOVA
A.O. Kovalevsky Institute of Biology of the Southern Seas, Russian Academy of Sciences, Sevastopol, Russia
Keywords: hydrocarbons, markers, water, bottom sediments, North Crimean Canal
Abstract
The North Crimean Canal (NCC) is an irrigation and water supply canal built in 1961-1971 to provide water to low-water and arid areas of Crimea. The canal waters are used for economic purposes, so investigation of the processes that were formed after the destruction of the Kakhovka Reservoir in 2023 and currently occur in the watercourse is urgent. In this work, we determined the concentrations of hydrocarbons (with safety assessment), features of the distribution of n-alkanes, potential sources of their income in the water and bottom sediments of the canal and adjacent water areas. The total concentrations of hydrocarbons and separately n-alkanes were determined by gas chromatography. Exceedance of the maximum permissible concentrations of hydrocarbons in water (0.05 mg/L) was detected in 50 % of samples in 2024, independently of sampling territory and time. The hygienic standard of hydrocarbon content (0.1 mg/L) was not exceeded in any sample, which makes the water suitable for drinking water supply. In all the bottom sediment samples collected in the canal in 2024, the standard level of HC content (50 mg/kg) was exceeded. Conditionally clean bottom sediments were detected only in the Biyuk-Karasu River bed. The genesis of hydrocarbons in 2024 in the waters of the canal and adjacent areas was mixed, mainly biogenic. The molecular composition of n-alkanes in the bottom sediments of the canal corresponded to the mixed origin of hydrocarbons with the predominance of allochthonous components.
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