Phenol compounds in the borehole 5G, Vostok station, after the unlocking of the subglacial lake

• Published in: Ice and Snow
• Main Authors: I. A. Alekhina, A. L. Moskvin, A. A. Ekaykin, V. Ya. Lipenkov
• Format: Article in Journal/Newspaper
• Language: Russian
• Published: Nauka 2017
• Subjects: антарктида; вторичный лёд; заливочная жидкость; ледяные керны; углеводороды; Science; Q; Lake Vostok; Vostok Station; Антарктида
• Online Access: https://doi.org/10.15356/2076-6734-2017-3-417-426; https://doaj.org/article/434ed79b220c477291e0b6f929247769

The main results after the first unlocking into the subglacial Lake Vostok were as follows: the Lake had been opened and not polluted; the water pressure within the lake was not balanced by a column of the drilling liquid that resulted in unplanned rise of water in the borehole up to 340 m. The main problem during the drilling in the lake ice was to prevent a pollution of water by the drilling fluid, which filled the borehole, and thus, to avoid a compression of the fluid which could be the main source of chemical and biological pollution of not only the Lake itself, but also the Lake water samples and ice cores. The article presents results of analysis of causes for the occurrence of phenolic compounds in the central channel in the core of secondary ice, being formed by the lake water that rose into the well after the first penetration (the range of depths was 3426–3450 m). It was found that the process, running within the borehole during the drilling, can be described as the fractionation of phenolic compounds, being contained in the filling liquid, to the water phase with its subsequent freezing. We have developed methods for the determination of concentrations of phenolic compounds in the original aviation kerosene and Freon HCFC-141b: 6. mg·l−1 and 0.032 mg·l−1, respectively. To analyze the composition of phenolic compounds in the extract of real filling liquid, located at the bottom of the borehole, the method of gas chromatography-mass spectrometry (GC-MS) was used. The corresponding peaks were quite well resolved and identified as phenol and its derivatives. The main components of the extract were phenol (20%), 2.5-dimethyl phenol (23,8%), 2,4,6-trimethylphenol, and other congeners of phenol. In our case, the Lake Vostok was not polluted during both, the first and second penetrations, however, the problem of human impact on these pristine and unique subglacial reservoirs remains extremely relevant. This impact includes not only direct water pollution of the lake by the drilling fluid, but also possible ...