杞麓湖水质参数季节性变化 Seasonal Variations of Water Quality Parameters in Lake Qilu

本文通过对杞麓湖2015年10月、2016年1月、5月、6月、10月水温(Temp)、溶解氧(DO)、叶绿素a(Chl-a)浓度、pH、浊度(Turbid+)进行垂直剖面监测数据分析，给出了杞麓湖水质现状数据，在此基础上讨论了杞麓湖水体水质参数季节性变化特征。分析结果表明，作为典型高原浅水湖泊的杞麓湖，其水质参数季节性变化明显，其中水温是受季节变化影响最显著的环境因子，受湖水扰动作用，混合性较强，加之由于湖水较浅，水温表现为垂直方向上变化不明显，水温随气温变化也不存在滞后效应。受杞麓湖盆地效应及气象站点海拔影响，监测时段内水温均略高于气温。流域降水集中在每年6~10月，水汽的滴落、蒸发对当地气温短时段变化有一定影响。杞麓湖对流域气候的调节作用显著，这一点在冬季尤为重要。湖水叶绿素a浓度、溶解氧受人类活动影响，季节性差异明显，空间差异较大。杞麓湖各季节pH在7.6~8.8之间波动，与藻类光合作用及底层有机物腐解关系密切。浊度在6月达到最大值，可能与藻类爆发、污水的集中输入以及湖水扰动底泥释放有关，对湖泊产生不利影响。湖水氮磷浓度均处于较高水平，外源污染输入是造成湖泊富营养化的主要原因，底泥的释放也是引起湖水营养盐浓度升高的又一原因。监测时段内，湖泊水质整体处于恶化状态，湖泊营养化加重、藻类浓度上升、生态效益退化。杞麓湖的生态环境治理需要科学的管理理念和措施、更多的资金投入和更有效的管理。 To understand the characteristics of water quality, their seasonal variations and vertical thermal dynamics, the water temperature (Temp), dissolve oxygen (DO), Chlorophyll-a (Chl-a), pH and Turbidity+ (Turbid+) of Lake Qilu, one of the typical plateau shallow lakes in Yunnan Plateau, were measured in October of 2015 and January, May, June, October of 2016. The data analysis results show a complex seasonal change picture of the water quality parameters. The water temperature did not change significantly in the vertical profile and following the air temperature. Affected by the Lake Qilu Basin and the altitude of weather station, the measured water temperature is slightly higher than the air temperature during the monitoring period. As the precipitation in Lake Qilu Basin concentrated in the rainy season, which lasted from June to October, short term local temperature was affected by the evaporation and raining processes. Certainly, the existence of Lake Qilu possesses a strong effect on the climate-environments of the drainage area, especially during the winter. The monitored data revealed large seasonal variations and spatial differences of the contents of chlorophyll-a, dissolved oxygen in the lake water, which are closely related with the human activities in the region. The pH values of Lake Qilu fluctuated between 7.6 - 8.8 that related to the photosynthesis of algae and the aerobic decomposition of organics at the bottom of the lake. The turbidity was higher in June, which might be related to the outbreak of algae, the polluted river water discharges into the lake and pollutant release from the lake sediment caused by lake water disturbance. The contents of both nitrogen and phosphorus in Lake Qilu are at a high level. It was concluded that the external pollutant input is one of the main sources of lake, and further the main factors inducing eutrophication of the lake water. During the monitoring period, the lake water quality as a whole is deteriorating, the lake nutrition is increasing, and the algae concentration is rising. It is the time to take serious measurements to protect the Lake Qilu from the further deterioration, even it is already too late to keep the lake function properly and effectively.