Talik

As Talik (plural Taliki or Taliks ) an area unfrozen soil is referred to in permafrost regions, caused by a local anomaly of the thermal, hydrological, hydrogeological and hydrochemical conditions. Most definitions of the term imply also that the unfrozen state must endure for at least one year in order to qualify as Talik, otherwise the Auftauboden would be classified as such. Heterogeneity also exists with regard to the question whether the unfrozen soil below the permafrost, the so-called Niefrostboden, can be described as Talik.

Taliki be classified in various ways, including on their location in the permafrost. In this example, open and closed Taliki be distinguished, the latter have no contact with the Auftauboden and are surrounded by frozen ground. Another classification is based on the physical cause of the unfrozen state. A form hydrothermal Taliki, which are due to the warming effect of the overlying surface water.

Taliki are a common phenomenon, even in the continuous permafrost zone in the temperature profile of the area. You can be caused by changes in the temperature budget and show permafrost degradation. On the other hand, they can also occur in an area is located on the climate in balance and are caused by local heat sources, in particular movements of groundwater may be responsible - as the frozen ground is impermeable to water, they are limited in permafrost areas on Taliki.

Classification

A basic criterion is a distinction according to the temperature. In most cases, this is higher than the freezing point of water. But there are also so-called kryotische Taliki whose temperature is below 0 ° C, for example because they are traversed by mineralized ground.

Depending on the location relative to the surrounding permafrost mainly of the following types:

  • Closed Talik: A Talik of this type has no contact with the Auftauboden, he is entirely surrounded by Permaforst or is at a location on the ground surface does not freeze at this. The latter can typically occur among lakes or rivers. The temperature here is due to the heat storage of surface water above 0 ° C, which is why it is non- kryotische Taliki.
  • Open Talik: If a Talik he is the permafrost completely penetrates referred to as "open". Such Talik connects the surface water with the water beneath the permafrost. In continuous permafrost open Taliki are rare, they can form under large lakes or rivers. Open Taliki can be kryotisch or non- kryotisch.
  • Lateral Talik: This is a Talik surrounded both the top and bottom by year-round frozen ground. Such Taliki can be kryotisch or non- kryotisch.
  • Insulated Talik: Taliki this type are entirely surrounded by frozen ground. They are often kryotisch, but can also be non- kryotisch.
  • Transient Talik, if a Talik gradually disappears by freezing of the soil, it is referred to as a "transient ." Typically, they develop under desiccating lakes. Here at propagation of permafrost develops a closed to an isolated and transient Talik.

Another classification distinguishes between the physical cause of the unfrozen state. There are five main types:

  • Thermal Talik: This is a non - kryotischen Talik that forms by the local thermal profile of the soil. Thermal Taliki are found mainly in areas with discontinuous permafrost, typically in the edge region of the permafrost area. In these areas, the sunlight is stronger, resulting in higher air and Bodentemeraturen are related. In addition, the insulating effect of seasonal snow cover can play a role and have a higher average temperature of the soil result.
  • Hydrothermal Talik: Such Talik caused by the warming effect of surface water, it is therefore non- kryotisch. It may be Taliki among lakes, or rivers, but also below the seabed there are Taliki this type. Furthermore, such Taliki may arise under levels that are flooded irregularly but frequently. Such Taliki may also be located under glaciers, however, if at the basic melt water flows.
  • Hydro Chemical Talik: This is a kryotischen Talik, in which the freezing is prevented by mineralized groundwater, which penetrates the Talik.
  • Geothermal Talik: A Talik of this type is produced by geothermal anomalies that are caused by processes within the Earth. Here, the geothermal heat flux transfers within the Earth along active faults in or near volcanoes on water under pressure beneath the permafrost. Thus, such Taliki are non- kryotisch.
  • Artificial Talik: These are caused by human activities in the permafrost region. Examples are Taliki under artificial water reservoirs, waste dumps, buildings or roads. In diskontinuierlen permafrost region ranging from the smallest changes in the heat balance to produce an artificial Talik that. You can be kryotisch or non- kryotisch.

Importance

Taliki and their development have a significant impact on the vegetation, surface and Grundwasserhydologie, the landscape, and also on human infrastructure in permafrost region. They also represent a very suitable environment for soil microorganisms, the organic material located there - can be converted into methane - such as dead plants and in permafrost preserved animal carcasses. Make methane releases into meltwater lakes in the permafrost area reportedly represents a significant source of methane in the atmosphere

Chemical hydrology Active layer Mineralization Mineralization (biology)
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