Evidence for regional climate change in the recent evolution of a high latitude pro-glacial lake

• Published in: Antarctic Science
• Main Authors: Webster, Jenny, Hawes, Ian, Downes, Malcolm, Timperley, Michael, Howard-Williams, Clive
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 1996
• Subjects: Glacial Lake; Lake Wilson; McMurdo Dry Valleys; Victoria Land; Antarctic Science
• Online Access: http://dx.doi.org/10.1017/s0954102096000090; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0954102096000090

Lake Wilson, a perennially ice-capped, deep (>100 m) lake at 80°S in southern Victoria Land was investigated in January 1993. Water chemistry and physical structure showed three distinct layers; an upper c. 35 m mixed layer of low salinity, moderately turbid water; a less turbid mid layer, 20 m thick of slightly higher salinity and supersaturated with oxygen; and a deep 20 m brackish layer (conductivity c. 4000 μS cm −1 ) with anoxic conditions in the lower 5 m. Extreme supersaturation of N 2 O (up to 400 times air saturation) together with high nitrate concentration (4000 mg m −3 ) was recorded in the deep layer. Phytoplankton biomass and photosynthetic activity was confined to the upper mixed layer and the band of supersaturated dissolved oxygen located at 40–55 m appears to represent a relict layer from when the lake level was lower. The evidence from a comparison of profiles between 1975 and 1993 suggests that Lake Wilson has risen 25 m since 1975, synchronous with a period of lake level rise in the McMurdo Dry Valleys lakes to the north at 77°S. Geochemical diffusion models indicate that Lake Wilson had evaporated to a smaller brine lake about 1000 yrs BP, which also fits the pattern shown by the McMurdo Dry Valleys lakes. Climate changes influencing lake levels have thus covered a wide area of southern Victoria Land.