干旱区生态环境知识资源中心

There is a long icebound season of frozen lakes in cold and arid regions. The ice, especially in shallow lakes, occupies a large proportion of water depth, from 1/3 similar to 2/3 of the depth. Therefore, the impact of lake ice for the lake ecosystem cannot be ignored. The process of freezing can discharge a great amount of pollutants. We examined the concentrations of pollutants in Ulansuhai Lake water from the beginning of freezing until full icebound. We found that the concentration of pollutants rose as the lake froze. For instance, the total nitrogen and total phosphorus concentration of water pollutants were 2 to 10 times and 6 to 10 times higher within the water as compared to the ice. With melting, those pollutants returned to the entire lake volume. The water layer below ice had high concentrations which resulted in a new endogenous pollution source. Using monthly field observation data in 2011, we carried out endogenous pollution estimates in Ulansuhai Lake and determined the influence of the freezing and melting process on the lake's environment. The new treatment was given by combining actual situation with study analysis results.