Saline
lakes are rare in the European inland. They can only be found in
Seewinkel and in central Hungary. Very big waters can be found in
other parts of the world e.g. in Kazakhstan, Mongolia, Australia
and the Etosha pan. But also from the global point of view, these
regions are rare. It is one of the main tasks to preserve these
unique landscapes. There are about 45 saline lakes between the
Neusiedler See and the Hanság that characterise like no other
landscape component the Seewinkel area.
Where do
theses shallow saline waters come from?
The creation
of the saline lakes along the east shore of the Neusiedler See
(Stinkerseen, Illmitzer Zicklacke...) is not completely explored
yet, but it might be linked to the formation of the lake
embankment. Sediments from the bottom of the lake were deposited by
water currents and ice movement. A breech in the embankment led to
erosion of an inland depression. This is where the saline lakes
could form.
The saline
lakes of the central Seewinkel (Lange Lacke, Wörthenlacken...) are
even older than the Neusiedler See itself: According to the
accepted Riedl-theory, so called pingos formed during the Würm
ice-age (115.000 to 10.000 years ago). Pingos prevented the Danube
from depositing it's sediments there. When the pingos melted, the
shallow basins filled with water.
About 13
million years ago, the area was part of the open sea. Huge
formations of sediment forced the sea to retreat to the east.
According to Husz a soda-carrying soil horizon developed during the
last interglacial period with arid climate conditions. The
groundwater rose and salt reached the surface by capillary action.
The regular desiccation helps to maintain the saline lakes. The
bottom of the saline lake is impermeable. If the groundwater
reaches this layer from below, salt rises by capillary action into
the system of the saline lake. If the groundwater level declines,
the salt concentration decreases and the lake desalinates and could
even disappear. The saline lakes differ from each other in their
chemical composition and soil substratum - that is why it is so
important to preserve each and every saline lake.
Between
the extremes
The water
level varies with the seasons, from high water levels in springtime
to desiccation in summer. Precipitation and evaporation play the
key role. The salt concentration of the saline lakes increases,
when the water level drops. The "soda snow" consists of sodium
carbonate (Na²CO³) but there can also be Glauber salt (Na2SO4),
Epsom salt (MgSO4) and common salt (NaCl).
Saline lakes
are extreme habitats not only because of their salinity and the
changing water level but also because of extreme variations in
night and day temperatures. Before total desiccation, temperatures
can range from 18 to 38°C.
Over the
course of a year, the water level can vary in depth between 70 cm
and total desiccation. Precipitation in autumn and winter
compensate the heavy evaporation in summer. Once there were more
than 100 saline lakes in this area, but most have been lost due to
human interference, some silted in naturally.