Major ions composition and spatiotemporal variation of water in Dishui Lake

Abstract:

Through measuring major ions of Dishui Lake water every two weeks from January to December in 2009, we concluded that the average total ion content of the lake was 1.82 g/L and the water of Dishui Lake was brackish.The major anion and cation were Cl^- and Na⁺ respectively. The water type was Cl^Na_Ⅲ according to Alekin classification. The total ion content decreased gradually in 2009, and the ion composition of the lake changed significantly with the proportions of Cl^- and Mg²⁺ decreasing and HCO₃^-, SO₄^2-, Ca²⁺increasing. Significant difference lay in the total ion contents among different sampling sites. The area around water sports club had the highest total ion contents while the lowest site was South Island district. As to the ion composition, no significant difference was observed among five sampling sites. Analyzing the relationship between the ion composition and total ion content in Dishui Lake, we concluded that the higher total ions concentration, the larger the proportion of Cl^- and the less the proportion of HCO₃^-. The water type of Dishui Lake was significantly different from other lakes in the lower reaches of the Yangtze River and common natural brackish lakes. The important information about total ions, ion composition and spatiotemporal variation of Dishui Lake were obtained which laid a good foundation for water chemistry and ecological research in the future.