Geology and bathymetry Sea of Azov

satellite image of sea of azov. shallow sea of azov distinguished deeper black sea. numbers: 1. dnieper river, 2. kakhovka reservoir, 3. molochna river, 4. molochny liman, 5. arabat spit, 6. sivash lagoon system, 7. karkinit bay, 8. kalamitsky bay, 9. crimea, 10. fedosiysky bay, 11. strait of kerch, 12. black sea, 13. sea of azov, 14. don river (russia), 15. taganrog bay, 16. yeysk liman, 17. beisug liman

the international hydrographic organization defines limit of sea of azov in kertch strait [sic] limit of black sea , defined line joining cape takil , cape panaghia (45°02 n) .

the sea considered internal sea of russia , ukraine, , use governed agreement between these countries ratified in 2003. sea 360 kilometres (220 mi) long , 180 kilometres (110 mi) wide , has area of 39,000 square kilometres (15,000 sq mi); smallest sea within countries of former soviet union. main rivers flowing don , kuban; ensure waters of sea have comparatively low salinity , fresh in places, , bring in huge volumes of silt , sand. accumulation of sand , shells results in smooth , low coastline, in numerous spits , sandbanks.

the sea of azov shallowest sea in world average depth of 7 metres (23 ft) , maximum depth of 14 metres (46 ft); in bays, silt has built up, average depth 1 metre (3 ft). sea bottom relatively flat depth gradually increasing coast centre. sea of azov internal sea passage atlantic ocean going through black, marmara, aegean , mediterranean seas. connected black sea strait of kerch, @ narrowest has width of 4 kilometres (2.5 mi) , maximum depth of 15 metres (49 ft). narrowness of kerch strait limits water exchange black sea. result, salinity of sea of azov low; in open sea 10–12 psu, 1 third of salinity of oceans; lower (2–7 psu) in taganrog bay @ northeast end of sea. long-term variations of salinity within few psu , caused changes in humidity , precipitation.

although more 20 rivers flow sea, north, 2 of them, don , kuban rivers, account more 90% of water inflow. contribution of don twice of kuban. kuban delta located @ southeast, on east side of kerch strait. on 100 km long , covers vast flooded area numerous channels. because of spread, delta has low contrast in satellite images, , hardly visible in map. don flows north large taganrog bay. depth there varies between 2 , 9 metres, while maximum depth observed in middle of sea.

typical values of annual inflow , outflow of water sea, averaged on period 1923 1985, follows: river inflow 38.6 km, precipitation 15.5 km, evaporation 34.6 km, inflow black sea 36–38 km, outflow 53–55 km. thus, 17 km of fresh water outflowing azov sea black sea. depth of azov sea decreasing, due river-induced deposits. whereas past hydrological expeditions recorded depths of 16 metres, more recent ones not find places deeper 13.5–14 metres. might explain variation in maximum depths among different sources. water level fluctuates 20 cm on year due snow melts in spring.

the taman peninsula has 25 mud volcanoes, of active. eruptions quiet, spilling out mud, , such gases methane, carbon dioxide , hydrogen sulfide, violent , resemble regular volcanic eruptions. of volcanoes under water, near shores of peninsula. major eruption on 6 september 1799, near stanitsa golubitskaya, lasted 2 hours , formed mud island 100 metres in diameter , 2 metres in height; island washed away sea. similar eruptions occurred in 1862, 1906, 1924, 1950 , 1952.

the current vertical profile of sea of azov exhibits oxygenated surface waters , anoxic bottom waters, anoxic waters forming in layer 0.5 to 4 metres (1.6–13.1 ft) in thickness. occurrence of anoxic layer attributed seasonal eutrophication events associated increased sedimentary input don , kuban rivers. sedimentary input stimulates biotic activity in surface layers, in organisms photosynthesise under aerobic conditions. once organisms expire, dead organic matter sinks bottom of sea bacteria , microorganisms, using available oxygen, consume organic matter, leading anoxic conditions. studies have shown in sea of azov, exact vertical structure dependent on wind strength , sea surface temperature, typically stagnation zone lies between oxic , anoxic layers.