Yu Yan, Liu De-Fu, Yang Zheng-Jian, Zhang Jia-Lei, Xu Ya-Qian, Liu Jin-Gao, Yan Guang-Han
College of Hydraulic and Environmental Engineering, China Three Gorges University, Yichang 443002, China.
College of Civil and Environmental Engineering, Hubei University of Technology, Wuhan 430068, China.
Huan Jing Ke Xue. 2017 Apr 8;38(4):1393-1402. doi: 10.13227/j.hjkx.201606085.
According to the data collected from the five monitoring sites in front of the dam in Thousand-island Lake in September 2015, the vertical distribution characteristics of dissolved oxygen (DO), water temperature, pH, turbidity, conductivity and phytoplankton were analyzed. The influencing factors of special stratification of DO and vertical distribution of phytoplankton were also discussed. The results showed that:① The vertical distribution of DO presented "the surface is higher than the underlying" mode. DO ranged from 1.95 mg·L to 8.25 mg·L and the average concentration was 5.10 mg·L. Low-oxygen zones appeared between 12 m and 20 m and the minimum concentration was 1.95 mg·L at 17 m. The concentration of DO maintained at a high level between 0 m and 12 m and the vertical variance was small. Sudden drop of DO occurred between 12 m and 20 m and there was an anoxic zone (<4.0 mg·L). The concentration of DO returned to normal level between 20 m and 38 m. Then it reduced under 38m as the water depth increased. The vertical distribution of pH showed the same trend with that of DO and their sudden change regions appeared in the same zone. ② Vertical phytoplankton biomass displayed significant difference. The phytoplankton biomass of S1, S2 and S3 presented:mid-layer > surface > bottom. But S4, S5 presented:bottom > surface > mid-layer. In addition, the depth between 20 m and 30 m was the best for the growth of phytoplankton. ③ The correlation analysis showed that DO and water temperature in the thermocline were significantly correlative. The range and degree of low-oxygen zones in Thousand-island Lake was determined by physical processes like thermal stratification of water and direct or indirect effects of the plankton. Phytoplankton and DO, pH showed significant negative correlation. The phytoplankton was mainly influenced by turbulent mixing and DO stratification in the surface layer while it was mainly influenced by light intensity at the bottom.
根据2015年9月从千岛湖大坝前5个监测点收集的数据，分析了溶解氧（DO）、水温、pH值、浊度、电导率和浮游植物的垂直分布特征。还讨论了DO特殊分层和浮游植物垂直分布的影响因素。结果表明：①DO的垂直分布呈现“表层高于底层”模式。DO浓度范围为1.95mg·L至8.25mg·L，平均浓度为5.10mg·L。在12m至20m之间出现低氧区，最低浓度在17m处为1.95mg·L。DO浓度在0m至12m之间保持在较高水平，垂直变化较小。在12m至20m之间DO突然下降，存在缺氧区（<4.0mg·L）。DO浓度在20m至38m之间恢复正常水平。然后在38m以下随着水深增加而降低。pH值的垂直分布与DO呈现相同趋势，它们的突变区域出现在同一区域。②浮游植物生物量的垂直分布存在显著差异。S1、S2和S3的浮游植物生物量呈现：中层>表层>底层。但S4、S5呈现：底层>表层>中层。此外，20m至30m之间的深度最适合浮游植物生长。③相关性分析表明，温跃层中的DO与水温显著相关。千岛湖低氧区的范围和程度由水体热分层等物理过程以及浮游生物的直接或间接影响决定。浮游植物与DO、pH值呈显著负相关。浮游植物在表层主要受湍流混合和DO分层影响，而在底层主要受光照强度影响。
