ISOTOPIC AND BIOGEOCHEMICAL CHARACTERISTICS OF TABULAR GROUND ICE ON THE YUGORSKII AND YAMAL PENINSULAS

Abstract

A possible source of moisture for the ground ice was determined from the sulfur and carbon isotopic tests of meltwater. The starting material for the investigation was collected in 1998-2000 from four tabular ground ice exposures on the Yugorskii (Shpindler thermocirque and Pervaya Peschanaya River valley) and Yamal peninsulas (Belushii Nos Cape, western Yamal and the Se-Yakha River near the Bovanenkovo gas-condensate field of the central Yamal). It was shown that the sulfur isotopic composition of sulfate-ion dissolved in meltwater from the Yugorskii Peninsula and central Yamal is close to the mean sulfur isotopic composition of atmospheric precipitation in the Arctic Region. Ice from the Belushii Nos Cape is enriched in suspended matter and shows the lightest isotopic composition of sulfate-ion demonstrating a greater influence of continent compared to ice from other locations. The organic carbon of suspended matter contained in ice shows a relatively homogeneous isotopic composition with average δ 13C ∼ -25‰ in all tabular ground ice exposures. At the same time, the δ13C-Corg values of particular ice samples vary considerably from -21.0 to -27.7‰. The δ13C-Corg and δ 13C-CH4 values in combination with the results of radiocarbon (14C) and microbiological investigations testify to microflora activity in the tabular ground ice.