汤溪水库的富营养化现状研究

Current eutrophication in Tangxi Reservoir of Guangdong Province

为了解汤溪水库的富营养化现状,于2000年丰水期和枯水期对该水库的水质和浮游生物分布进行了调查。结果表明,汤溪水库综合营养状态指数(TLI)在30～50之间,属中营养水平。浮游植物丰度为0.81×10~6～6.57×10~6cells·L^(-1),丰水期高于枯水期。浮游植物以蓝藻、绿藻和硅藻为主,其优势种主要为水华微囊藻(Microcystis flos-aquae)、颗粒直链藻(Melosira granulata)、极小直链藻(Melosira minmum)和衣藻(Chlamydomonas sp.)等富营养化指示种。浮游动物丰度为43.25～812.2ind.·L^(-1),其优势种也多为富营养化指示种,如:螺形龟甲轮虫(Keratella cochlearis)、角突臂尾轮虫(Brachionus angularis)、前节晶囊轮虫(Asplanchna priodonta)和广布中剑水蚤(Mesocyclops leuckarti)。与1984年相比,该水库由硅藻型变为蓝藻型,其营养水平与浮游植物丰度都显著增加。在2000年一次微囊藻水华发生时,水体表层浮游植物丰度高达11.97×10~6cells·L^(-1)。

In the flood season and dry season of 2000, the water quality and plankton distribution of Tangxi Reservoir were investigated to evaluate its trophic state. According to the comprehensive trophic level index (TLI), the values of Tangxi reservoir were between 30 and 50. It showed that the reservoir was mesotrophic. The phytoplankton abundances varied from 0.81 ×106 to 6.57 ×106 cells · L-1, and were higher in the flood season than in the dry season. The phytoplankton was primarily composed of Cyanophyta, Chlorophyta and Bacillariophyta. Most of the dominant species were eutrophication indicators such as Microcystis flos-aquae, Melosira granulata, Melosira minmum and Chlamydomonas sp.. The zooplankton abundances were between 43.25 ind.· L-1 and 812.2 ind. · L-1, and the dominant species were mostly eutrophication indicators: Keratella cochlearis, Brachipnus angularis, Asplanchna priodonta and Mesocyclops leuckart. In comparison with 1984, the dominant phylum changed from Cyanophyta to Bacillariophyta. Both trophic state and the phytoplankton abundance increased greatly. During a Microcystis bloom occurred in 2000, the maximum phytoplankton abundance in the surface water reached 11.97×l06 cells · L-1.