【摘要】 为探讨三峡水库运行初期小江回水区水体的光学特性,2007年5月~2008年5月对回水区5个断面水下光合有效辐射(PAR)与常规水质指标进行监测,分析了真光层深度的时空特征及其影响因素。研究区域真光层深度空间差异不明显,但季节变化显著,冬季最高,夏季最低。回归分析表明光合有效辐射(PAR)衰减系数与透明度、总悬浮物浓度有显著的相关性(R2=0.861 9,R2=0.764),与叶绿素a相关性不明显(R2=0.011 3)。进一步研究分析表明真光层深度、总悬浮物浓度、叶绿素a主要受小江河口流量、小江回水区水位的影响,复杂的水动力条件与独特的水文条件是影响三峡水库小江回水区真光层深度变化的主要因素。更多还原

【Abstract】 Spatiotemporal variations of euphotic depth and its causing factors are investigated for the early impounding stage of Three Gorges Reservoir in the backwater area of Xiaojiang River that is a tributary of the Yangtze River.Water samples were taken at five cross-sections in the backwater area during the period May,2007 through May,2008.The photosynthetically active radiation(PAR) and conventional water quality monitoring indices were derived from the water samples for analysis in this study.The results show that there are no significant spatial variations in the mean euphotic depth at the five sampling cross-sections.However,seasonal variations are strong with the highest value of euphotic depth in the winter and the lowest value in the summer.Regressions between the attenuation coefficient of PAR with the secchi disc transparency and with the concentration of total suspended solids(TSS) show that the two correlations appeared to be strong as revealed by the coefficient of determination R2 = 0.861 9 for the former and 0.764 for the latter,which indicates that the TSS influence on the euphotic depth is significant.The study also finds that there is no significant correlation between the attenuation coefficient of PAR and the chlorophyll-a(Chla) concentration as shown by the low value of R2 = 0.011 3.This result suggests that the euphotic depth,the concentrations of TSS and Chla are all influenced by the river flow and water stage in the backwater area of Xiaojiang River.The spatiotemporal variation of euphotic depth is thus mainly influenced by the sophisticated hydrodynamic and hydrological conditions in the river-reservoir hybrid system.更多还原