太湖湖滨带藻密度与水质、风作用的分布特征及相关关系

Temporal and Spatial Distribution of Algal Density and its Relationship with Water Quality and Wind Factor in the Littoral Zone of Lake Taihu

为研究太湖湖滨带水体藻密度、水质及风作用的时空分布特征,于2010年春、夏季调查了太湖湖滨带的水质、藻密度,同时结合风级、风向等数据,运用偏相关法分析了藻密度分布与水质、风作用的相关关系.结果表明:春季湖滨带水体藻密度低于夏季,平均值分别为1.88×106、1.75×108L-1,竺山湾、梅梁湾、西部沿岸藻密度较高.太湖湖滨带水体ρ(TP)、ρ(TN)、ρ(NO3--N)、ρ(NH3-N)、ρ(COD Mn)春季平均值分别为0.10、4.48、0.99、2.36、6.46 mgL,夏季分别为0.16、2.09、0.60、0.43、6.73 mgL,其中高值主要分布在竺山湾、西部沿岸、梅梁湾湖滨带;在时间上,ρ(TN)、ρ(NH3-N)、ρ(DO)春季较高;ρ(TP)、pH夏季较高.太湖湖滨带春、夏季风作用均以向岸的正作用力为主,夏季和春季风力作用平均值分别为0.26和0.73.风作用值较高的区域出现在梅梁湾、贡湖、西部沿岸.偏相关分析结果表明:春、夏季藻密度分布均与风作用值呈显著正相关;春季只有透明度与藻密度的分布显著相关,夏季藻密度分布与ρ(COD Mn)、ρ(SS)呈显著性正相关,而与pH呈显著负相关.在富营养化严重的太湖,N、P等营养盐已经不再是藻类暴发的限制因子,而风作用及与之密切相关的湖流,北部竺山湾、梅梁湾似口袋状的地理形态,是影响藻密度分布的重要因素;另外,入湖河流污染对北部、西北部湖滨带自生藻类的滋生,水生植物、浮游动物对藻类分布也会有不同程度的影响.

The water quality and algal density of the littoral zone around Lake Taihu was determined in spring and summer of 2010. The wind information during two sampling periods was collected and collated during the same period. The temporal and spatial distributions of water quality, algal density and wind information in the littoral zone were studied. The partial correlations between algal density and the factors of water quality and wind function were analyzed. The results showed that the algal densities in spring （ 1.88 x 106 L-l ） were lower than those in summer （1.75 x 10s L-1 ）. The algal densities were higher in the sampling sites of Zhushanwan, Meiliangwan and west side of the lake. The temnoral and snatial variation nf water cmalitv in the littoral znne nf Lake. Taihu was significant The concentrations of TP, TN, NO3 -_N, NH3-N, CODMn were 0. 10, 4.48,0. 99,2. 36,6.46 mg/L in spring, were 0. 16,2.09,0. 60, 0. 43,6. 73 mg/L in summer, 2010. Higher concentrations of TP, TN, NO3 -N, NH3-N and CODM,, and lower transparency were found in Zhushanwan, Meiliangwan and the west side. The positive wind function values were dominant in both spring and summer, with the averages of 0. 26 and 0.73, respectively. The higher wind function values were often found in Meiliangwan,Gonghu and the west side. The partial correlation analysis revealed that the algal density significantly positive was correlated wind function values in both spring and summer. Transparency was the only factor for water quality that was significantly correlated with algal density in spring, while the concentration of CODMn and SS had significant positive and pH had significant negative correlations with algal density in summer. The results indicated that nitrogen and phosphorus were not the limitation factors for the algal bloom in Lake Taihu that produces serious eutrophic condition. However, wind function, lake current and the ＂pocket-liking＂ geographic pattern of Zhushanwan and Meiliangwan, are important driving factors for algal distribution. Additionally, the pollution from inlet rivers, aquatic plants and zooplanktons can affect on the distribution of algal density in the littoral zone of Lake Taihu.