Major and trace elements, δ13C, and polycyclic aromatic hydrocarbons in the Late Pleistocene ice wedges: A case-study of Batagay yedoma, Central Yakutia

Abstract

We studied the ionic composition of ice, the content of suspended and dissolved trace- and major elements in ice, values of δ13С, and the composition of PAHs of inclusions in the Late Pleistocene syngenetic ice wedges of the Batagay yedoma. For the first time, the complex geochemical study of Batagay megaslump was carried out. The ice of the upper and lower complex of different ages was studied. Mineralisation of the Late Pleistocene ice wedges of Batagay yedoma ranges from 66.56 to 424.8 mg L−1, from ultrafresh to desalinated, the ionic composition of the ice is bicarbonate-calcium and corresponds to snow formed under the influence of continental air masses. The proportion of Ca contained in dissolved form is not more than 20–30%; as for the other elements, the proportion of Mg, K, Na, Al, Fe, Mn, Sr, Ba in suspended form is greater than 90%. The content of trace elements in inclusions in ice wedges and soils is equal, which confirms the pedogenic origin of the inclusions in ice. According to our data, values of δ13С in lipids of the pedogenic material in ice decrease with depth. The lowest values (values of δ13С less than −30‰) were observed in the ice wedge of the upper complex at a depth of 7.4–8.6 m. The increase of δ13C values of lipids from pedogenic material in ice wedges with depth is due to the landscape change from grassland ecosystems to forest ecosystems, and may also be influenced by the increased frequency of fires that occurred during the transition to forest ecosystems and the disappearance of large herbivores.