Monimolimnion

Mermomictic^([sic – meaning meromictic]) lakes may have an extremely high calcium carbonate content in the monimolimnion.

Source: wiktionary

The resulting pH-drop causes a dissolution of carbonate material which has been biogenically precipitated in the epilimnion. This carbonate is recycled to the surface waters during the autumn and winter circulation and can be transported through the outflowing rivers to the oceans. A similar situation exists in temporary or permanently stratified waters of freshwater, brackish and marine environments. Examples of such environments are the monimolimnions of meromictic lakes, the Baltic Sea […] and Norwegan fjords where a high CO₂ input is maintained by vigorous degradation of organic matter.

Source: wiktionary

The higher salinity of the monimolimnion, and therefore the greater density, prevents wind-driven mixing. The cause of meromixis in Green Lake is the inflow of saline ground-water springs below a depth of about 20 m.

Source: wiktionary

The monimolimnion is not a static state but is subject to change, depending mainly on the weather conditions, because of basin's shallowness and the almost stable temperature of the spring waters.

Source: wiktionary