The Gulf of finland

Measures The square of the Finland bay is 29,5 thousand kilometers. The length of the bay from the Hanko Penninsula to Saint Petersburg is 420 kilometers, the width from 70 kilometers in narrow entrance to a gulf to 130 kilometers in the widest part at the meridian of the Mozhnyi Island. In the Nevskaya Bay it diminishes to 12 kilometers.

The relief of coasts Petergoff is situated on the under flooded Southern coasts of the Baltic Sea. The Baltiisko-Ladoga glint about 40 m high runs along the entire coast. The southern cost of the one side are rather aligned, weakly sinuous (like in eastern Estonia), on the other side it is more rugged (like in west Estonia and in Russia, where the deep gulfs such as Narvskii, Koporskii locate). They are separated by Kurgalskii, Soikinskii and Karvaldaiskii peninsulas.

Formation 300-400 hundred years ago in Palaozoic the whole territory of the modern Finland gulf was covered by sea. The sedimentary deposits of that time represented by sandstone, sand, clay, and limestone cover the basement as a thickness above 200 meters. The latter consists of granite, gneiss and diabase.

Ice cover activity The modern relief is a result of the ice cover activity. The last Valdai glaciation took place 12 000 years ago. After the glacia stepped back the Littorin Sea was generated. The sea level was 7-9 meters above the modern level of the Baltic Sea. The levels of glacial reservoirs decreased gradually and their area diminished. That’s why the reservoir bottoms are characterized by the origination of the stepped terraces going down in the direction of the Finland Bay. 4 000 years ago the sea progradated and Finland Bay shoals transformed into islands. The modern stronger uplift of the Scandinavian shield leaded to the skew of the Finland Bay surface. Via that reason the northern costs of the bay are high and rocky, but southern – under flooded.

Vegetation Forest vegetation is represented by pine and firry forests, and also by greenwood (birch, willow, rowan, aspen, black and gray alder). There are plots of wetland vegetation throughout the Gulf of Finland, mainly consisting of bulrush and common reed, and also many water plants grow there, such as lily white, yellow spatter-dock, Urrutia spiked and whorled, sedge acute cane reed canary grass, valerian Maritime, Marine klubnekamysh. Shoal water flora is represented by Naiad Marine, RUPP korotkonozhkovaya and others. Both the main coast landscapes and islands on the Gulf of Finland are attributed to subzone of southern taiga (forest, meadow and mursh communities).

Extinct animals In recent years, gray seal pups and the Baltic Ringed Seal have been regularly found on the coasts of the gulf. These spieces are listed in the Red book as rare and vulnerable.

Depth The Finland bay is very shallow. The bottom profile decreases from the narrow entrance to the top. The especially abrupt change occurs near Narva-Yesuu, that’s why this place is called the Narva Wall. The average depth is 38m, the maximal depth is 100m, the depth of the Nevskaya Bay is 6 m and less, and in the coast zone it diminishes until 1m. The Sea Channel is built on the Nevskaya Bay bottom for the passage of ships.

Temperature rigime The average winter temperature of the water is near 0 °C and summer temperature is about 15—17 °C at the surface and 2—3 °C at the bottom. The bay froze from the end of November to the end of April and in the warm winter it does not froze the whole year. Freezing starts in the eastern part of the bay and gradually spreads to the west. The strong wave disturbances and onsets are typical with the western wind and triggers the flooding.

Salinity Because of the big input of the fresh water from rivers, especially from the Niva River, representing 2/3 of the whole flow, the water of the bay bears very weak salinity. It changes from 0,2 to 5,8 ‰ at the surface to interval from 0,3 to 8,5 ‰ at the bottom.

Ecological problems Superfluous content of nitrogen and phosphorus in water area is a result of washout from the fertilized fields, with municipal drains of cities and a waste of some factories and plants. Accumulation of heavy metals — mercury, lead, copper, zinc, cadmium, cobalt, nickel. Pollution by oil

Solutions Each year, international forum called “The Baltic Day” is held in Saint-Petersburg. The forum brings together more than 500 members, their decisions influence politics of many countries, for example Russia. Thanks to one of the major water companies of Saint-Petersburg, Vodocanal, nowadays more than 91% of wastewater is cleared. By 2015 they plan to clear about 98% of wastewater – it’s one of the best results in the world.