Organic Compounds and Metals in the Sediments of Meromictic Lakes Separated from the Kandalaksha Gulf of the White Sea

Abstract

It is shown that a large number of organic compounds of autochthonous and allochthonous nature are formed in the bottom sediments of separating waterbodies in the Kandalaksha Gulf of the White Sea, despite their subarctic position. The average content of Corg, Ntot, Stot, aliphatic hydrocarbons, and polycyclic aromatic hydrocarbons in the bottom sediments are 5.33, 0.78, 0.53%, 817 μg/g, and 261 ng/g, respectively, which are significantly higher than in sediments of the open areas of the White Sea. The eutrophication of these waterbodies depends on their connection with the sea. It was found that anoxic pelitic sediments of separating lakes are enriched in Cu, Cd, Mo, Hg and U compared to sediments of the open sea bays in Kandalaksha Gulf. Thereby, the Hg and Mo contents are 2 and 14 times higher than their maximum permissible concentrations (MPC) (0.3 and 3 µg/g, respectively). A positive correlation with total sulfur (r 0.8, р 0.01) indicates the prevailing occurrence of these metals in form of poorly soluble sulfides.