风浪对太湖水体中胶体态营养盐和浮游植物的影响

为了解不同风浪条件下太湖水中胶体态营养盐和浮游植物含量的特征, 选择不同风速情况进行现场观测和采样, 用切向流超滤法获取胶体, 测定胶体态有机碳、氮、磷及其他形态营养盐含量. 同时收集浮游植物样品, 测定其密度和生物量. 结果表明, 在风速小于4m/s时胶体氮(CN)和胶体磷(CP)含量随风速变大而升高, 而在风速大于4 m/s时其含量不再升高, 甚至略有降低; 叶绿素a(Chl-a)、浮游植物密度、蓝藻密度和蓝藻生物量均在风速小于4m/s时随风速增大而升高, 在风速大于4 m/s时随风速增大而降低, 说明小风浪有利于蓝藻生长或漂浮, 而大风浪对其生长或漂浮不利. CN和CP含量与浮游藻类含量呈显著正相关, 表明在藻类生长旺盛的夏季, 太湖水中胶体氮、磷的主要来源为藻类产物.

Effect of Wind-Induced Wave on Concentration of Colloidal Nutrient and Phytoplankton in Lake Taihu

In order to find out the characteristics of colloidal nutrient and phytoplankton under different wind conditions in Lake Taihu, observation were carried out and samples were collected. Colloid was collected by using cross-flow ultrafiltration system. Organic carbon, nitrogen, and phosphorus in colloidal, dissolved and other fractions of water samples were determined, and concentration and biomass of phytoplankton were also determined. The result showed that the concentration of colloidal nitrogen (CN), colloidal phosphorus (CP) increased with the increasing of wind speed when the wind speed was less than 4m/s, and did not increase or even decreased with the increasing of wind speed when the wind speed was more than 4m/s. The concentration of Chl-a, phytoplankton, cyanobacteria, and biomass of cyanobacteria increased with the increasing of wind speed when the wind speeds was less than 4m/s, and decreased with the increasing of wind speeds when the wind speed was more than 4m/s. It was indicated that the small wind-induced waves are of advantage to the float or growth of cyanobacteria while the big wind-induced waves are of disadvantage to the float or growth of cyanobacteria. Concentration of CN and CP are significantly correlated with concentration of phytoplankton and cyanobacteria, indicating that algae and their production are main sources of CN and CP in summer in Lake Taihu.