热带亚热带水库浮游植物叶绿素a与磷分布的特征

于丰水期和枯水期对广东省19个大中型水库的浮游植物叶绿素a和磷(P)进行采样和测定,分析了P和叶绿素a的分布特征及其相关性。结果表明P的浓度和叶绿素a含量较低的有流溪河、新丰江、公平和白盆珠水库;而枯、丰两期P的浓度和叶绿素a含量均较高的有契爷石、石岩、鹤地和大镜山水库;其余12个水库均属于季节性差异较明显的水库,在丰水期由入流带来较多的P,而枯水期则因入流相对较少,P的含量也较低。大部分水库在枯水期P限制现象比较严重,而丰水期则有所缓解。P限制程度的不同导致了丰水期和枯水期水库浮游植物种群组成和叶绿素含量的变化。丰水期的优势种类P半饱和浓度较高,在枯水期这些种类不再是优势种的组成部分。而一些P半饱和浓度较低的种类,在丰水期和枯水期都成为各个水库的优势种。通过相关性分析,正磷酸盐(PO₄^3--P)与叶绿素的相关系数较高,总磷(TP)与叶绿素的相关系数则相对较低。从时间上来看,枯水期PO₄^3--P与叶绿素的相关性高于丰水期;从空间上看,大坝处PO₄^3--P与叶绿素的相关性高于入水口。

Distribution of Chlorophyll-a and phosphorus in subtropical reservoirs, South China

Chlorophyll-a and phosphorus were measured in 19 reservoirs in Guangdong province, South China in flood and dry seasons of 2000. The results showed that Liuxihe reservoir, Xinfengjiang reservoir, Gongping reservoir and Baipenzhu reservoir, which located in the up-stream of the rivers, had low concentration of phosphorus and chlorophyll-a all the year. On the contrary, Qiyeshi reservoir, Shiyan reservoir and Hedi reservoir as well as Dajingshan reservoir, which located in down-stream of the rivers or located in Leizhou Peninsula, where is well developed farm area, had high concentration of both phosphorus and chlorophyll-a. The other reservoirs had obvious seasonal patten: the concentration of phosphorus were higher in the flood season than in the dry season. Phosphorus limitation was more serious in a dry season, which caused a significant change in the phytoplankton species composition from a flood season to a dry season. The dominant species in the flood season had a high half-saturation concentration of phosphorus, and they lost the advantage in the dry season. The species, Microcystic spp. and Melosira spp., which have a low half-saturation concentration of phosphorus dominate in both the flood and the dry seasons. The correlation coefficient between PO43--P and chlorophyll a was higher in dry season than in flood season, and higher near the dam than in the riverine. It was higher than the correlation coefficient between TP and chlorophyll a concentrations.