The vertical distribution of 27 elements in bottom sediments reflects the modern history of the hypersaline lagoon

Abstract

Knowledge of the distribution of various elements in the bottom vertical cores helps to assess current levels and to reconstruct the history of a water body. There is little to no bioturbation of bottom sediments in hypersaline lagoons/lakes, and vertical distribution of elements in the sediments is not distorted. The vertical distribution of 27 elements was studied in one of the Crimean hypersaline marine lakes. Their determination was carried out in layers one centimeter thick, which were taken from a depth of 1 cm to 28 cm. Using the technogenic radionuclide 90Sr, the time intervals when various layers of bottom sediments were formed had been previously determined. The concentrations of most elements, as well as their ratio, changed quasi-cyclically. For most of the elements for which such changes were noted, the maximum peak values were in the layers that formed in 1976 and 2006. The authors concluded from this that there appears to be a natural rhythm with a period of about 30 years. Not only a concentration of technogenic radionuclide 90Sr but also Mo, Ba, Tl, Sb, Se, and Ag reacted strongly to the accident at the Chernobyl nuclear power plant in 1986 due to atmospheric fallout and transportation of elements via the Dnieper river waters through the North Crimean Canal.