These Lakes Also Have Dissolved Minerals
The fossil water inside the subglacial lakes has high levels of dissolved minerals, which support the microbial lifeforms that live there. The minerals include carbon and other nutrients, which affect the chemical composition of the coastal areas of the Southern Ocean.
The lakes periodically drain out into the Southern Ocean and then are filled again by the water that flows and collects together. As the water flows out into the ocean, the minerals flow out and join the salty Southern Ocean. As more water flows in, the minerals recollect. The carbon levels can replenish themselves within 4.8 to 11.9 years.