material - Photometry - Water
analyses - Limnology museum in Listvjanka
Limnology and Hydrology
The Lake Baikal is the world´s deepest lake (1637 m)
and one of the largest, stretching like a giant crescent, 636 km long and up
to 80 km wide. It contains 23600 km3 of water, or about 20 % of the
Earth´s non-frozen surface freshwater. The Baikal is a drainage lake.
Around 300 rivers with a catchment area of 560 000 km2 flow into
it, but there is only one discharge: the Angara. The total input to the lake
consists of the tributaries (83 %), precipitation (13%) and condensed moisture
just as groundwater (4%). Losses are attributed to discharge (85%) and evaporation
(15%). The time of water residence is long (~ 350 years).
Topographically, the lake consists of three main basins (south, middle and north).
The southern and middle basins are separated by the sediment delta of the Selenga
river. The northern basin is separated by a submarin mountain ridge.
The climate of the country around Baikal is distinctly continental. The Baikal
causes a climate mitigation effect by its water mass. The summer and winter
temperatures of the area around the baikal are not as extreme as in areas which
are not influenced by the Baikal. The mean annual air temperature is –1,7
The Baikal is a cold lake. Although immediately after the clearance of ice in
May and June, the Baikal begins to build up heat from solar radiation, the high
heat capacity of the water and its great volume cause that the temperature of
the water does not rise very much. So the lake remains relatively cold. A surface
temperature of +3 to +4 °C is maintained for a long time. Only in the shallows
and in bays does it rise up to +10 to +12 °C. A water temperature of +16
up to +18 °C can be found in July and August along the shores of the southernmost
end of the lake, for example near the mouth of Selenga. Low heat conductivity
is typical for water which gives off heat very slowly. Another peculiarity is
the fact, that it achieves its greatest density at +4 °C. This peculiarity
is the main reason for the spring and summer warming of the surface layer of
water down to around 300 meters. Dense water at a temperature of +4 °C sinks
and mixes with cold water, gradually balancing the temperature in the surface
layer. In June the lake goes through a homothermic period, wich is a levelling
out of temperature in the top 300 meter layer. During the state of homothermy,
the temperature of the water in the top 300 meter layer gradually rises. In
June a period of temperature stratification occurs. A thin, well warmed surface
layer arises separated from deep water by a layer of sudden significant temperature
decrease. In September, the water of the Baikal begins to cool and in November
it again goes through a state of homothermy. Below the active layer is a body
of water that plays a small role in temperature exchange with the atmosphere.
It is characterized by a relatively even temperature, which decreases to +3,4
°C towards the bottom.
The currents in the lake Baikal are caused by various factors, for example winds,
changes in the atmosphere, pressure, the rotation of the earth, and the input
of large amounts of water via tributaries.
The water of the Baikal is exceptionally pure. It has a very low level of mineralisation,
only up to 96,6 mg/L. The water is defined as being of the carbonate calcium
type. River water and especially the water of Selenga influence the concentration
of individual ions in the water. Some components vary by location and season.
The low level of mineralisation of the Baikals water is due to the low mineralisation
of the water of its tributaries. The low mineralisation of the water of the
tributaries is caused by the fact that the Baikal basin is composed mostly of
metamorphic and magmatic rock lacking minerals that are easily dissolved. The
low mineralisation level is also influenced by the low temperatures in the lake.
An outstanding feature of the lake Baikal is the variety and originality of
its fauna and flora. 80% of 2635 known species and subspecies of hydrobionts
in the lake are found nowhere else, meaning that they are endemic. But there
are many other quanitative characteristics of the Lake, which surprise with
their unique parameters. For example are there more than 300,000,000 omuls and
around 100,000 Baikal seals living in the Lake. The 230 Gammaridae types (flea-cancer-types)
are responsible for the unique self-purification of the Baikal. These animals
have a high filtration performance. They degrade algae, bacteria and dead organic
matter and filtrate 83 km3 of water every day. They provide the purity
of the water.