Lake Untersee

Lake Untersee
Lake Untersee Location of Lake Untersee in Antarctica
Location	Queen Maud Land, Antarctica
Coordinates	71°20′S 13°27′E / 71.333°S 13.450°E / -71.333; 13.450Coordinates: 71°20′S 13°27′E / 71.333°S 13.450°E / -71.333; 13.450
Type	glacial
Etymology	"Lower Lake" (from German "unter" [lower] + "see" [lake])
Basin countries	(Antarctica)
Max. length	6.5 kilometres (4.0 mi)
Max. width	2.5 kilometres (1.6 mi)
Surface area	11.4 square kilometres (4.4 sq mi)
Max. depth	169 metres (554 ft)
Surface elevation	563 metres (1,847 ft)
Frozen	Permanently
References	Wand et al.

Lake Untersee (German: Untersee, "Lower Lake") is the largest surface freshwater lake in the interior of the Gruber Mountains of central Queen Maud Land in East Antarctica. It is situated 90 kilometres (56 mi) to the southwest of the Schirmacher Oasis. The lake is approximately 6.5 kilometres (4.0 mi) long and 2.5 kilometres (1.6 mi) wide, with a surface area of 11.4 square kilometres (4.4 sq mi), and a maximum depth of 169 metres (554 ft). The lake is permanently covered with ice and is partly bounded by glacier ice.

Lake Untersee is an unusual lake, with pH between 9.8 and 12.1, dissolved oxygen at 150 percent supersaturation, and very low primary production in the water column. Despite the high oxygen supersaturation in most of the lake, there is a small sub-basin at the southern end that is anoxic and its sediments may have a higher methane concentration than those of any other known lake on Earth. Much of the primary production is in microbial communities that grow on the floor of the lake as stromatolites. The water temperature varies between 0.5 °C (32.9 °F) and 5 °C (41 °F) and the ice cover on the lake is 2–6 metres (6.6–19.7 ft) thick. The ice cover may have persisted for over 100,000 years, and some scientists studying climate change fear significant environmental changes associated with global warming in the coming decades. In the past, the water chemistry of the lake has been compared to Clorox. However, the chemical activity of bleach is due to Cl⁻ in addition to a pH that is higher than that measures in Lake Untersee, and Lake Untersee does not have high chlorine or chlorite concentrations.

Lake Untersee lies in the interior of the Gruber Mountains of central Queen Maud Land in East Antarctica, which is roughly on the same longitude as Huab, in the Skeleton Coast National Park on the northern coast of Namibia. It is situated 90 kilometres (56 mi) to the southwest of the Schirmacher Oasis.Aurkjosen Cirque lies at the east side of the lake.