Seasonal Stratification Characteristics of Vertical Profiles of Water Body in Lake Lugu

For the purpose of exploring seasonal stratification characteristics of water hydrochemistry, the seasonal dynamics and vertical thermal stratification of water temperature in Lake Lugu, the vertical profiles of water temperature (Temp), Electrical Conductivity (EC), Dissolved Oxygen (DO), pH and Chlorophyll-a (Chl-a) of Lake Lugu were monitored in January, April, July and October 2015, respectively. The results indicated that water body of Lake Lugu appeared thermal stratification in spring, summer and autumn, however, in winter, the water temperature in vertical direction was homogeneous. The thermocline was located between 10 and 25 m, nevertheless, it moved down to range from 20 to 30 m in autumn. In addition, water temperature in hypolimnion was maintained almost as a constant and consistent with annual temperature, indicating water body was stable all along. The results showed that the thermal stratification had some influences on vertical distributions of DO, EC, pH and Chl-a. The significant stratification of DO, EC and pH was found, especially in summer, DO and pH values in thermocline peaked due to greatly stable thermal stratification and temperature increase. In hypolimnion, DO concentration and pH value were very small. Moreover, Chl-a concentration was higher in the surface and lower in the bottom water, implying that human should be highly alter to prevent the emergence of a large area of algae in Lake Lugu. EC took on decreasing variation, besides, lower in the thermocline. While,Lugu Lake water salinity was lower and substantially constant (~ 0.10‰), without considering the effects of salinity, both in vertical sections and in epilimnion, thermocline and hypolimnion, there all existed a simple linear function of the relationship between EC andwater temperature, showing that Lugu Lake was affected by natural climate and keeps natural state.