Water isotopic-geochemical composition in the Trekhtsvetnoe meromictic lake on the White Sea coast

The isotopic features of Lake Trekhtsvetnoe in the White Sea coast area were studied in 2012–2015 in both winter and summer. Lake Trekhtsvetnoe is a water body, separating from the sea, with constant vertical stratification throughout the observation period. Its isotopic, hydrophysical, and biological characteristics have been studied. By the isotopic profile of lake water body, three zones can be identified in the lake: (1) 0–1 m: mixolimnion zone with δ¹⁸O varying from–12 to–11.1‰; (2) 1.0–3.0 m: zone with transitional properties with δ¹⁸O varying from–11.1 to–5.5‰; (3) 3.0–7.6 m: monimolimnion zone with highest values of δ¹⁸O—from–5.5 to–4.7‰.