Chen Xiao-Hua, Li Xiao-Ping, Qian Xiao-Yong, Hu Shuang-Qing
Shanghai Academy of Environmental Science, Shanghai 200233, China.
State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200062, China.
Huan Jing Ke Xue. 2017 Jan 8;38(1):113-120. doi: 10.13227/j.hjkx.201607041.
Based on water quality monitoring data of Lake Erhai from 1990 to 2013,the yearly and seasonally response characteristics of algal chlorophyll-a to total nitrogen (TN),total phosphorus (TP) and water temperature was investigated using quantile regression method.It indicated that water temperature was always the primary limiting factor of algal biomass indicated by chlorophyll a (Chl-a) across recent 24 years,but its limiting effect on algal Chl-a content was kept descending sharply and replaced much by nutrients (e.g.P,N) with the increasing eutrophic level.Especially the slope values of TP on Chl-a were kept ascending from -0.3 to 0.8.Since 2002,the positive effect of TN on Chl-a presented slow descending tendency,and P became the most important limiting nutrient factor of algal growth.According to the seasonal variation analysis,water temperature and N had dominant effects on algal Chl-a in spring and autumn,but they were replaced by P in the case of Chl-a>8 mg·m in spring.In summer,N and P had strong interactive impacts on the algal growth,and the positive effect of P was stronger than that of N in the case of Chl-a>3 mg·m.In winter,algal biomass was co-limited by temperature and P.It suggested that P reduction is the prior choice of eutrophication control of Lake Erhai,and simultaneously reducing N load is necessary in the background of global warming.In addition,so far a emergency controlling measure should be taken to monitor algal blooming due to sharp ascending of water temperature within a few days in spring and autumn.
基于1990 - 2013年洱海水质监测数据，采用分位数回归方法研究了藻类叶绿素a对总氮（TN）、总磷（TP）和水温的年际及季节响应特征。结果表明，水温一直是近24年来叶绿素a（Chl-a）所指示的藻类生物量的主要限制因素，但其对藻类Chl-a含量的限制作用急剧下降，随着富营养化程度的增加，逐渐被营养物质（如磷、氮）所取代。特别是TP对Chl-a的斜率值从-0.3持续上升至0.8。2002年以来，TN对Chl-a的正向作用呈缓慢下降趋势，磷成为藻类生长最重要的限制营养因子。根据季节变化分析，水温与氮在春季和秋季对藻类Chl-a起主导作用，但在春季Chl-a>8mg·m时被磷取代。夏季，氮和磷对藻类生长有强烈的交互影响，在Chl-a>3mg·m时磷的正向作用强于氮。冬季，藻类生物量受温度和磷的共同限制。这表明，减少磷排放是洱海富营养化控制的优先选择，同时在全球变暖背景下减少氮负荷也很有必要。此外，目前应采取应急控制措施，以监测春秋季水温在数天内急剧上升导致的藻类水华现象。
