滇池叶绿素a的时空变化及水体磷对藻类生长的影响

The Spatial and Temporal Dynamics of Chlorophyll a Concentrations and Its Relationship with Phosphorus in Lake Dianchi

水体藻类生长的时空变化及其与磷的关系对研究水体富营养化十分重要。本研究采用GPS定位,对滇池海埂、斗南、罗家村、新街、昆阳等5个代表性样点水体叶绿素a的含量进行了为期1年的动态监测,全面分析了不同区域、不同层次、不同时期滇池水体中叶绿素a含量的时空动态变化特征及水体磷对藻类生长的影响。结果表明,全湖水体叶绿素a含量的平均浓度在12.33～39.28mg·L-1之间,总体趋势以夏季和秋季较高,冬季较低;以表层、底层较高,中层较低。但不同位点变化高峰和趋势不同。滇池水体不同层次叶绿素a的浓度变化范围是6.04～72.70mg·L-1,不同区域水体叶绿素a平均含量1年的变化范围是:表层为7.00～72.70mg·L-1,中层为9.20～63.89mg·L-1,底层为6.04～58.06mg·L-1。各区域水体叶绿素a的含量以海埂最高,全年在11.34～72.70mg·L-1间变化,其次是昆阳,罗家村、斗南较低。新街水体中叶绿素a的含量最低,全年变化范围为6.04～28.06mg·L-1。滇池全湖水体总磷与叶绿素a周年变化呈显著正相关;滇池水体中藻类的生长与总磷、可溶性磷在空间变化上呈显著正相关。

Phosphorus （P） is important to algae growth, causing eutrophication of Lake Dianchi. To study the effect of P on algae growth and the relationship between the spatial and temporal distribution of algae growth and P concentration in Lake Dianchi, the dynamics of chlorophyll a （Chl a） concentrations, total P and soluble P concentrations at different water depths in five representative sites of Lake Dianchi, Haigeng, Dounan, Luojiacun, Xinjie, and Kunyang from May 2003 to May 2004 were monitored. The results showed that, the average concentration of Chl a in Lake Dianchi ranged from 12.33 to 39.28 mg· L^-1 with a trend of higher in summer and autumn, and lower in winter. But the peak time and concentrations were different among the five sampling sites. The Chl a concentration in different water levels ranged from 6.04 to 72.70 mg· L^-1 with a trend of higher in surface and bottom layers, and lower in the middle layer. The average annual variations of Chl a concentrations in the five sampling sites were 7.00～72.70, 9.20～63.89 and 6.04～58.06 mg· L^-1, in surface, middle and bottom layers, respectively. During the peak time of algae growth, the Chl a concentration was higher in the surface layer compared to that in middle and bottom layers, but the annual variations of Chl a concentration in different water depths had no significant difference. Among the sampling sites, the Chl a concentration was the highest in Haigeng, averaging 31.81 mg· L^-1 （ranging from 11.34 to 72.70 mg· L^-1）, followed by Luojiacun, Kunyang, Dounan, and Xinjie with the average Chl a concentration 20.90, 20.85, 19.45 and 17.15 mg· L^-1, respectively. The Chl a concentration in Xinjie was the lowest with an average of ranging from 6.04 to 28.06 mg· L^-1. The Chl a concentration positively correlated with the annual variations of total P concentrations in Lake Dinachi, and positively correlated with total P and soluble P concentrations in spatial variations.