三峡澎溪河回水区流速对藻类原位生长速率的影响

为明晰不同流速水平对三峡支流回水区库湾藻类原位生长的影响,本文采用可调速的环形实验槽,选择三峡水库不同运行状态(低水位、高水位),对三峡澎溪河高阳平湖库湾藻类生物量(用叶绿素a浓度表示)变化特征进行原位受控实验.通过流速在0(对照)、0.1、0.2和0.3 m/s的实验发现,夏季低水位阶段澎溪河水域光热充足,但流速升高(0.2m/s)对藻类原位比生长速率具有一定影响.大体上,高阳平湖水域藻类原位比生长速率与流速水平呈对数关系.冬季高水位运行期间,流速的升高将可能在一定程度上促进水柱扰动,成为维持藻类在上层水体受光生长、避免下沉的主要因素.该时期,采用调节流速、流量的方法抑制藻类生长的难度相对较大.

Effects of flow speed on the change of in situ growth rates of algae in Pengxi River backwater zone, Three Gorges Reservoir

To understand the influence of flow speed on algae growth rates in reservoirs, in situ experiment using stirring experimental tank was carried out in different water level periods (low water level and high water level) in Pengxi River backwater area, a tributary of the Three Gorges Reservoir. Four different treatments, i.e. flow speeds of 0, 0.1, 0.2 and 0.3 m/s, were selected in the experiment. In summer low water level period, light and temperature conditions were feasible for the growth of algae. Increase in flow speed (>0.2 m/s) would have significant impacts on the growth of algae. In general, relationships between algal growth rates and flow speeds were in accordance with logarithmic function. In winter, a high water level period, increasing in flow speed would increase in turbulence in water column, preventing sedimentation of algae. In this period, regulating flow speed and discharge to control algal growth might be difficult.