Wird der Große Aralsee meromiktisch? Verfolgung der laufenden Veränderungen im physikalischen und biogeochemischen Regime des weltweit dynamischsten Gewässerökosystems.
Zusammenfassung der Projektergebnisse
The project was dedicated to detailed assessment of the current state of the Aral Sea following the two unique lake manipulation events: diverting of the major inflows started in 1960ies, which lead to shrinkage of one of the largest lakes to about 10% of its previous size, and construction of a dam separating southern and northern parts of the Aral Sea, which resulted in extreme salinity differences between the remaining parts of the lake. In view of the importance of the Aral Sea as an unique example for understanding of lake manipulation consequences and the lack of available regular observations, the project was specifically focused on obtaining field data about the mixing conditions in the semi-separated parts of the Aral Sea, their dependence on salinity and water level variations and their effects on the biogeochemical processes. The main original project hypothesis stated that the largest remaining basin of the Aral Sea is turning into a meromictic lake with deep waters isolated from the atmosphere and accumulating greenhouse gases due to anaerobic production. Extensive field studies on the remaining water basins of the Aral Sea revealed complex physical and biogeochemical processes driven by extreme gradients of salinity and strong variations of water level. Water exchange between the hypersaline southern Aral Sea and the brackish North Aral Sea leads to formation of meromictic conditions in large semi-isolated parts of the lake and triggers intense deep methane production by anaerobic microbial activity. The meromixis remains unstable and can be destroyed by water level decrease during droughts. As a result, periods of methane accumulation are alternated by methane outbursts into the atmosphere on decadal time scales. The results abandon the original project hypothesis and demonstrate a highly dynamic behavior of mixing and stratification in the Aral Sea, affected by the regional water diversion and the Global Change. The project outcomes provided the first quantitative results on the seasonal mixing regime of different parts of the Aral Sea with important implications for both fundamental understanding of lake physics under extreme external forcing and assessment of water management consequences on regional scales. The uncovered features of the drying lakes dynamics - formation and destruction of meromixis by horizontal salinity exchange, extreme winter mixing of arid hypersaline lakes accelerated by exothermic heat of salt precipitation, restoration of the seasonal mixing regime to a “transient” one between dimictic and polymictic by water diversion - provide an important insight into physical and biogeochemical consequences of lake manipulation.
Projektbezogene Publikationen (Auswahl)
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Former bay of the desiccating Aral Sea as the newly formed world’s largest heliothermal lake . Copernicus GmbH.
Izhitskiy, Alexander; Kirillin, Georgiy; Goncharenko, Igor; Kurbaniyazov, Abilgazy & Zavialov, Peter
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The world’s largest heliothermal lake newly formed in the Aral Sea basin. Environmental Research Letters, 16(11), 115009.
Izhitskiy, Alexander S.; Kirillin, Georgiy B.; Goncharenko, Igor V.; Kurbaniyazov, Abilgazy K. & Zavialov, Peter O.
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Multi-model projections of future evaporation in a sub-tropical lake. Journal of Hydrology, 615, 128729.
La Fuente, Sofia; Jennings, Eleanor; Gal, Gideon; Kirillin, Georgiy; Shatwell, Tom; Ladwig, Robert; Moore, Tadhg; Couture, Raoul-Marie; Côté, Marianne; Love Råman Vinnå, C. & Iestyn Woolway, R.
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The North (Small) Aral Sea after 15 years of recovering: physical and biogeochemical outcomes of the lake-wide conservation experiment.. Copernicus GmbH.
Izhitskiy, Alexander & Kirillin, Georgiy
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Thermal conditions and lake metabolism in the ice-covered North Aral Sea. Copernicus GmbH.
Kirillin, Georgiy; Izhitsky, Alexander & Kurbaniyazov, Abilgazi
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Increasing warm-season evaporation rates across European lakes under climate change. Climatic Change, 177(12).
La Fuente, Sofia; Jennings, Eleanor; Lenters, John D.; Verburg, Piet; Kirillin, Georgiy; Shatwell, Tom; Couture, Raoul-Marie; Côté, Marianne; Vinnå, C. Love Råman & Woolway, R. Iestyn
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The effects of salinity and river runoff on idealized brackish ice-covered lakes . Copernicus GmbH.
Sharifi, Fatemeh Sadat; Hinkelmann, Reinhard; Hattermann, Tore & Kirillin, Georgiy
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Three-dimensional modeling of diffusion-gravity flows in ice-covered lakes. Environmental Fluid Mechanics, 25(2).
Sharifi, Fatemeh Sadat; Hinkelmann, Reinhard; Hattermann, Tore & Kirillin, Georgiy
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Three-dimensional modeling of diffusion-gravity flows in ice-covered lakes. Environmental Fluid Mechanics, 25(2).
Sharifi, Fatemeh Sadat; Hinkelmann, Reinhard; Hattermann, Tore & Kirillin, Georgiy
