Features of the spatial and seasonal distribution of hydrocarbons in water of the North Crimean Canal, Crimea

The North Crimean Canal is a watercourse originating from the Kakhovka Reservoir and flowing into the Crimean Peninsula. The canal is an important source of drinking water supply and is also used to irrigate agricultural lands and fill fish farms. Due to its location, in recent years its functioning has not been stable, and the processes occurring along the canal have been poorly studied. In this study, we determined the content (with a safety assessment), features of spatial and seasonal distribution, and potential sources of hydrocarbons in the water of the North Crimean Canal, Crimea. During the study period (from March to November 2023) in the primary canal, the content of aliphatic hydrocarbons did not exceed sanitary standards (0.05 mg·L⁻¹). Their increased concentrations in the secondary canals could be associated with the input of organic substances into the canal water as it moves across the Crimean Peninsula. The composition of n-alkanes had temporal and spatial variability. In the period from spring to autumn, the content of autochthonous compounds decreased sharply. The share of allochthonous compounds increased as a consequence of the natural processes. The analysis of biogeochemical markers showed that autochthonous compounds produced by phytoplankton predominated in the spring–summer period. Subsequently, they had less importance, and the main share was accounted for allochthonous n-alkanes.