Effects of increased sodium concentration on the re-distribution of calcium and magnesium in different media in Taihu Lake, China

Taihu Lake, the third largest freshwater lake in China, has experienced rapid salinization in the past decades, however, little is known about its impact on the distribution of base cations (especially Ca and Mg) in the lake environment. In this work, the adsorption-exchange experiment was conducted using the sediment from Taihu Lake mixed with the Na solution with different concentrations. the experimental and the MINTEQ model data was used to quantitatively explain this exchange process and compared with the actual Taihu environment. The datea showed that Taihu exist obvious cation exchange process caused by salinization, and this process could alter on the distribution of Ca and Mg between the water and sediment in the lake, especially in water; i.e., elevated Na concentration can significantly increase Ca and Mg concentration in the solution, with Ca being preferably exchanged over Mg from the sediment, and the reason for this ionic preference could be attributed to the exchange affinity between base cations by MINTEQ.