Lake VostokLake Vostok (озеро Восток, ozero Vostok) is the largest of Antarctica's almost 400 known subglacial lakes. Lake Vostok is located at the southern Pole of Cold, beneath Russia's Vostok Station under the surface of the central East Antarctic Ice Sheet, which is at above mean sea level. The surface of this fresh water lake is approximately under the surface of the ice, which places it at approximately below sea level. Measuring long by wide at its widest point, it covers an area of making it the 16th largest lake by surface area.
OxygenOxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as well as with other compounds. Oxygen is Earth's most abundant element, and after hydrogen and helium, it is the third-most abundant element in the universe. At standard temperature and pressure, two atoms of the element bind to form dioxygen, a colorless and odorless diatomic gas with the formula O2.
Climate changeIn common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to Earth's climate. The current rise in global average temperature is more rapid than previous changes, and is primarily caused by humans burning fossil fuels. Fossil fuel use, deforestation, and some agricultural and industrial practices increase greenhouse gases, notably carbon dioxide and methane.
Anoxic watersAnoxic waters are areas of sea water, fresh water, or groundwater that are depleted of dissolved oxygen. The US Geological Survey defines anoxic groundwater as those with dissolved oxygen concentration of less than 0.5 milligrams per litre. Anoxic waters can be contrasted with hypoxic waters, which are low (but not lacking) in dissolved oxygen. This condition is generally found in areas that have restricted water exchange.
Iron(III) oxide-hydroxideIron(III) oxide-hydroxide or ferric oxyhydroxide is the chemical compound of iron, oxygen, and hydrogen with formula FeO(OH). The compound is often encountered as one of its hydrates, FeO(OH)·nH2O [rust]. The monohydrate FeO(OH)·H2O is often referred to as iron(III) hydroxide Fe(OH)3, hydrated iron oxide, yellow iron oxide, or Pigment Yellow 42. Anhydrous ferric hydroxide occurs in the nature as the exceedingly rare mineral bernalite, Fe(OH)3·nH2O (n = 0.0–0.25).
Fluvial processesIn geography and geology, fluvial processes are associated with rivers and streams and the deposits and landforms created by them. When the stream or rivers are associated with glaciers, ice sheets, or ice caps, the term glaciofluvial or fluvioglacial is used. Fluvial processes include the motion of sediment and erosion or deposition on the river bed. The movement of water across the stream bed exerts a shear stress directly onto the bed.
Trophic state indexThe Trophic State Index (TSI) is a classification system designed to rate water bodies based on the amount of biological productivity they sustain. Although the term "trophic index" is commonly applied to lakes, any surface water body may be indexed. The TSI of a water body is rated on a scale from zero to one hundred. Under the TSI scale, water bodies may be defined as: oligotrophic (TSI 0–40, having the least amount of biological productivity, "good" water quality); mesotrophic (TSI 40–60, having a moderate level of biological productivity, "fair" water quality); or eutrophic to hypereutrophic (TSI 60–100, having the highest amount of biological productivity, "poor" water quality).
HypolimnionThe hypolimnion or under lake is the dense, bottom layer of water in a thermally-stratified lake. The word "hypolimnion" is derived from λιμνίον. It is the layer that lies below the thermocline. Typically the hypolimnion is the coldest layer of a lake in summer, and the warmest layer during winter. In deep, temperate lakes, the bottom-most waters of the hypolimnion are typically close to 4 °C throughout the year. The hypolimnion may be much warmer in lakes at warmer latitudes.
Sedimentary rockSedimentary rocks are types of rock that are formed by the accumulation or deposition of mineral or organic particles at Earth's surface, followed by cementation. Sedimentation is the collective name for processes that cause these particles to settle in place. The particles that form a sedimentary rock are called sediment, and may be composed of geological detritus (minerals) or biological detritus (organic matter). The geological detritus originated from weathering and erosion of existing rocks, or from the solidification of molten lava blobs erupted by volcanoes.
Hypoxia (environmental)Hypoxia refers to low oxygen conditions. Normally, 20.9% of the gas in the atmosphere is oxygen. The partial pressure of oxygen in the atmosphere is 20.9% of the total barometric pressure. In water, oxygen levels are much lower, approximately 7 ppm or 0.0007% in good quality water, and fluctuate locally depending on the presence of photosynthetic organisms and relative distance to the surface (if there is more oxygen in the air, it will diffuse across the partial pressure gradient).
