太湖湖滨带浮叶植物菱(Trapa quadrispinosa Roxb)对氮素再悬浮的影响

大型浅水湖泊沉积物的再悬浮是湖泊生态系统的重要过程之一，也是影响湖泊内源负荷的主要因子之一。大型水生植物在抑制沉积物再悬浮方面有重要作用。通过测定浮叶植物生长区内外的沉积物再悬浮速率、沉积物总氮含量和水中总氮浓度，探讨太湖湖滨带浮叶植物菱（Trapa quadrispinosa Roxb）对沉积物中氮素再悬浮的影响。研究结果发现菱对沉积物的再悬浮有良好的抑制作用，在研究期间，菱生长区内的平均沉积物再悬浮速率为218.46 g dw m-2d-1，生长区外为658.13 g dw m-2d-1。随着沉积物的再悬浮，在生长区内平均每天每平方米有719.63 mg N（每年每平方米262.66 g）被带入水中，在生长区外相应的数字为1 536.14 mg（每年每平方米560.69 g）。另外在研究中发现上层沉积物总氮含量受风浪影响较大，与沉积物再悬浮速率呈负相关。恢复浮叶植物能有效控制湖泊沉积物再悬浮，降低湖水氮负荷。

EFFECT OF A FLOATING-LEAVED MACROPHYTE TRAPA QUADRISPINOSA ROXB ON NITROGEN RESUSPENSION IN THE LITTORAL ZONE OF LAKE TAIHU

The effect of a floating-leaved macrophyte Trapa quadrispinosa Roxb on nitrogen resuspension from sediment was studied with sediment traps placed within(inner zone) and outside(outer zone) of the macrophyte stand in Lake Taihu.During the study period,the average sediment resuspension rate was 658.13 g dw m~(-2) day~(-1) in outer zone and 218.46 g dw m~(-2) day~(-1) in inner zone;With the resuspended sediment,1 560.96 and 718.06 mg N m~(-2) day~(-1) was brought to the water column in outer zone and in inner zone respectively,suggesting that the nutrient loading due to sediment resuspension was considerable high in Lake Taihu.The results also revealed that the total nitrogen concentration of the upper sediment had a negative relationship to the sediment resuspesion rate.Thus it could be concluded that floating-leaved macrophyes are able to reduce nutrient resuspentsion significantly from sediment.