Physical, chemical and biological processes in Lake Vostok and other Antarctic subglacial lakes

Over 70 lakes have now been identified beneath the Antarctic ice sheet. Alt hough water from none of the lakes has been sampled directly, analysis of l ake ice frozen (accreted) to the underside of the ice sheet above Lake Vost ok, the largest of these lakes, has allowed inferences to be made on lake w ater chemistry and has revealed small quantities of microbes. These finding s suggest that Lake Vostok is an extreme, yet viable, environment for life. All subglacial lakes are subject to high pressure (similar to 350 atmosphe res), low temperatures (about -3 degreesC) and permanent darkness. Any micr obes present must therefore use chemical sources to power biological proces ses. Importantly, dissolved oxygen is available at least at the lake surfac e, from equilibration with air hydrates released from melting basal glacier ice. Microbes found in Lake Vostok's accreted ice are relatively modern, b ut the probability of ancient lake-floor sediments leads to a possibility o f a very old biota at the base of subglacial lakes.