中文摘要：

通过2015年1月、4月、7月、10月水温、电导率、溶解氧、pH及叶绿素a监测数据对水体温度的季节动态及其垂直分层结构进行分析,探讨了泸沽湖水体水化学性质的季节性分层特征。结果表明：泸沽湖水体在春、夏、秋季出现明显的热力分层现象,冬季水温在垂向上接近同温状态,夏季温跃层位于10～25 m水深处,而秋季温跃层下移至20～30 m处。均温层水温维持在9.5～10℃与泸沽湖年均温一致,说明均温层水体稳定且处于相对恒温状态,是湖区年均温的反映。热力分层结构对电导率、溶解氧、pH及叶绿素a变化有一定影响,致使水体电导率、溶解氧、pH出现明显的分层现象,尤其在夏季,气温升高,热力分层现象显著,溶解氧和pH在温跃层内出现峰值,自峰值处向上、向下均呈递减趋势,均温层处于缺氧状态且p H值较小。虽然叶绿素a在温跃层以下维持较低水平,整体不高,但在表层有突然增高的现象,应予以高度警示,防止泸沽湖出现大面积藻类繁殖甚至局部性爆发。电导率垂向上呈递减变化,在温跃层内降低幅度较大。泸沽湖水体盐度基本保持恒定（约0.10‰）,在不考虑盐度效应的情况下,无论是在垂直断面上还是在变温层、温跃层及均温层中,电导率与水温之间存在一简单线性函数关系,证明泸沽湖仍受自然气候影响,保持自然水体状态。

英文摘要：

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 Chla. 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.