蠡湖水体透明度的时空变化及其影响因素

为揭示浅水湖泊水体SD(透明度)下降的主导因子,根据2012—2013年现场调查资料和历史监测资料,分析了浅水湖泊蠡湖SD的时空分布特征、变化规律及主要影响因素,并重点探讨了SD与ρ(TSS)(TSS为总悬浮物)、ρ(Chla)和ρ(DOC)的相互关系. 结果表明:SD在年内变化范围为20.0～209.0 cm,平均值为64.1 cm,总体上呈西蠡湖大于东蠡湖、湖心大于沿岸区的分布趋势；春、夏、秋、冬四季的SD分别为(51.1±15.1)、(41.3±10.6)、(28.3±7.4)和(127.1±43.2)cm,表现为冬季>春季>夏季>秋季,冬季SD平均值可达127.1 cm,而秋季仅有28.3 cm. 多元回归分析表明,ρ(TSS)是影响水体SD的最主要因子,其次为浮游藻类生物量；SD与ρ(TSS)呈幂函数关系,拟合方程为y=220.61x-0.545 0. 

Dynamic Spatial and Temporal Changes in Water Transparency and Their Influencing Factors in Lihu Lake

Lihu Lake, a typical shallow lake, is in a transitional period from muddy and rich with algae to clear and rich in submerged plants. Since environmental comprehensive management engineering of the lake began in 2003, the water quality of Lihu Lake has been greatly improved as evidenced by decreasing ρ(TN), ρ(TP) and ρ(Chla) as the key indices of eutrophication. However, the SD and ρ(TSS), two typical sensory indices, have not significantly improved. To reveal the dominant factors of low water SD in the shallow lake, the spatial and temporal distribution characteristics, patterns and key influencing factors of SD in Lihu Lake were analyzed by both field survey and investigation of historical monitoring data from 2012-2013. The relationships among SD, ρ(TSS), ρ(Chla) and ρ(DOC) were investigated. Results showed that the annual SD was from 20.0-209.0 cm, with a mean value of 64.1 cm. The SD in the western part of Lihu Lake was higher than that in the eastern part, while the SD in the center of the lake was greater than that of the shore areas. The SD values in spring, summer, autumn and winter were (51.1±15.1), (41.3±10.6), (28.3±7.4) and (127.1±43.2)cm, respectively, with the decreasing order of winter > spring > summer > autumn. The SD in winter reached 127.1 cm, whereas it was only 28.3 cm in autumn. Results of multivariate regression analysis showed that ρ(TSS) was the most important factor affecting water SD, followed by planktonic algae biomass. The relationship between water SD and ρ(TSS) could be well fitted by a power function, y=220.61x-0.5450. The results provide a scientific basis for improving water quality and SD of Lihu Lake, and simultaneously offer technical support for submerged plant recovery.