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RESEARCH ON ENVIRONMENTAL-FRIENDLY SAMPLING TECHNOLOGY OF ANTARCTIC SUBGLACIAL LAKES

Nowadays it is generally recognized that a vast network of lakes, rivers, and streams exists thousands of meters beneath Antarctic Ice Sheets. As of 2016, 402 subglacial lakes with published references have been identified. Estimates indicate that the total surface area of the subglacial lakes is nearly 10 % of the ice sheet’s base, and the volume exceeds 10 000 km3. Sealed from the Earth’s atmosphere for millions of years, subglacial aquatic environment may provide unique information about microbial evolution, the past climate of the Earth, and the formation of the Antarctic ice sheet. The discovery of subglacial aquatic environments has opened an entirely new area of science in a short period of time. The recent stage of exploration requires direct sampling of these aquatic systems. The subglacial water most likely contains life, which must adapt to total darkness, low nutrient levels, high water pressures and isolation from atmosphere.


                                              

The locations of Antarctic subglacial lakes [Wright and Siegert, 2012]

The main function of the proposed RECoverable Autonomous Sonde (RECAS) is exploration of subglacial lakes with minimal chemical and microbial contamination. The sonde makes it possible to access subglacial water without connecting it to the modern atmosphere. The RECAS is equipped with electrically powered melting tips located at the upper and lower ends of the apparatus. The thermal drill can melt a hole to ice sheet bottom and is able to move upwards. It includes two electrically powered thermal drill bits, heated body, and coiling system.

All down-hole RECAS components will be sterilized using a combination of chemical wash, hydrogen peroxide vapor (HPV) and ultraviolet (UV) sterilization prior to deployment. The melted water is not recovered from the hole and it refreezes behind the sonde. The power and signal line is released from the coil inside the sonde. When sampling and monitoring are complete, the coil motor is activated and the top drill bit is powered. The sonde begins to recover himself to the surface by spooling the cable and melting overlying ice with the help of the upper drill bit. Besides sampling, subglacial sonde will measure pressure, temperature, pH, and conductivity of subglacial water.



Conceptual 3D model of the RECAS



The first laboratory tests of RECAS prototype are scheduled for early 2018, field tests are planned in season 2018-2019, in the area of Chinese Antarctic station Zhongshan. The project is sponsored by Ministry of Science and Technology of China (Project No. XXXXXX).





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