滇池水体磷的时空变化与藻类生长的关系

The spatial and temporal variations of phosphate concentrations and their relationships with algal growth in Lake Dianchi, China

水体磷的时空变化与藻类生长的关系对研究水体富营养化具有十分重要的作用。采用GPS定位,对滇池海埂、斗南、罗家村、新街、昆阳等5个代表性位点监测断面水体总磷、可溶性磷及叶绿素a含量进行了为期1年(2003年5月至2004年5月)的动态研究,并在滇池海埂位点进行了日变化试验,全面分析了滇池不同区域、不同层次、不同时期水体总磷和可溶性磷的年变化、日变化及水体氮/磷比对藻类生长的影响。结果表明,滇池水体磷与藻类生长呈现显著的年变化和日变化特征,显示了滇池全湖水体总磷与叶绿素a周年变化呈显著正相关,水体可溶性磷与叶绿素a呈正相关趋势;海埂位点水体总磷与叶绿素a日变化呈显著正相关,水体可溶性磷与叶绿素a日变化呈显著的负相关,水体氮磷比与叶绿素a呈显著正相关。表明水体磷负荷对藻类生长影响呈现显著的水体区域性和水层差异性和季节性,藻类生长主要吸收水体中的可溶性磷,暗示了滇池水体磷是藻类生长的主要限制因子之一。

Phosphorus （P） concentration is one of the major factors stimulating algal growths in Lake Dianchi. Studying the spatial and temporal variations of total P （TP）, soluble P （SP） concentrations and their effects on algal growth could help understanding the mechanisms of the eutrophication of Lake Dianchi. Dynamic changes of TP, SP and chlorophyll a concentrations at different depths of water were determined regularly at five representative sites of Lake Dianchi, namely Haigeng, Dounan, Luojiacun, Xinjie, and Kunyang located with GPS, respectively from May 2003 to May 2004. Daily changes of TP, SP and chlorophyll a concentrations were studied in Haigeng site. The results showed that, both TP and SP in Lake Dianchi had significant annual and daily variations, which were related to algal growth, TP concentrations were found significantly positively correlated with annual variation of chloro-phyll a concentrations. SP had only positively correlation trend with chlorophyll a concentration. TP concentration positively corre-lated with the daily variations of chlorophyll a concentration in the Haigeng site of Lake Dianchi. But SP concentrations had negative correlations with the daily variations of chlorophyll a. It is indicated that algal growth in Lake Dianchi was affected by water TN/TP in the lake. The results indicated that the effects of TP and SP concentrations on algal growth in Lake Dianchi varied with different sites, water depths and seasons. Soluble phosphorus （SP） concentration is subject to algal growth as a direct P supplying source, Phosphorus is one of the major limiting factors for algal growth in Lake Dianchi.