底泥再悬浮对东湖水体初级生产力的影响

EFFECTS OF RE-SUSPENDED SEDIMENT ON THE PRIMARY PRODUCTION IN THE DONGHU LAKE

为研究底泥再悬浮对东湖初级生产力的影响,通过模拟东湖通道施工导致的底泥再悬浮过程,用原位黑白瓶法测量了水体初级生产力,同步测定受试水体的光强、营养盐以及藻类叶绿素荧光活性,结果表明,随着再悬浮底泥含量的增加,水体出现明显的光衰减现象,光强显著降低(P<0.05);总氮总磷浓度升高;藻类最大光化学效率(Fv/Fm)上升;水体呼吸作用显著增强(P<0.05),总初级生产力与净初级生产力先增大后减小。与不含再悬浮底泥的对照组相比,水体再悬浮底泥含量50—100 g/L处理组具有较高的初级生产力;相对其他处理组,再悬浮底泥含量200 g/L处理组的初级生产力显著降低(P<0.05),且其净初级生产力为负值。研究结果表明,在一定范围内的底泥再悬浮通过增加水体营养盐含量的方式提高水体初级生产力,较大含量的再悬浮底泥则通过影响水体光强降低初级生产力,该结果确认了东湖通道施工引起的底泥再悬浮对水域生态系统的影响,值得引起关注和重视。

To examine the effect of suspended sediment on the primary production in the Donghu Lake, field investigation was carried out with the modified black and white bottles. The light intensity, nutrient concentrations and chlorophyll fluorescence were measured. The results showed that with the increased content of resuspended sediments, light intensity decreased significantly （P〈0.05）, TP concentration and the maximum photochemical efficiency （Fv/Fm） increased significantly （P〈0.05）, the respiration was significantly enhanced （P〈0.05）, the gross primary productivity and net primary productivity increased at first and then decreased. Suspended sediment at 50-100 g/L significantly increased primary productivity via the enrichment of the nutrient but dramatically repressed the gross primary productivity at 200 g/L even with a negative net primary productivity through significantly decreasing the light intensity in the water column （P〈0.05）. We revealed the impacts of Donghu Channel project on the freshwater ecosystem of the Donghu Lake, which need further attention.