关键词: 太湖, 磷, 悬浮物, 营养盐释放, 再悬浮通量, 风浪扰动, 消浪工程

Abstract:

In order to evaluate the effects of wave dissipation engineerings on reducing sediments resuspension and internal nutrient release in Lake Taihu, sediment traps were settled on July 15 to 17, 2005 in the wave dissipation engineering area to measure resuspension flux of sediments. Water of different layers was sampled so as to know the vertical distribution of nutrient concentration. The maximum value of the upper resuspension flux was 7.22 g /d·m2 and the maximum value of the lower resuspension flux was 41.8 g /d·m2 on July 16 when the wind speed was 3 m/s; The minimum value of the upper resuspension flux was 24.7 g/ d·m2 and the minimum value of the lower resuspension flux 48.4 g/ d·m2 on July 17 when the wind speed was 5 m/s. Sediments resuspension flux has a close relation to windwave disturbance. When comparing the resuspension fluxes in and out of the engineering area, it was obvious that wave dissipation engineering has weakened the windwave disturbance to sediments, with an effect to prevent sediment resuspension, and therefore a lower nutrient resuspension flux was observed. Organic matter in suspended solid also reduced with the increase of suspended solid materials. Accordingly, phosphorus in suspended solid per unit will decrease too. Dissolved phosphorus did not increase in the observation,though sustained windwave disturbance may bring much dissolved phosphorus from sediments into overlying water. Suspended solids can absorb dissolved phosphorus in the water. As a result, dissolved phosphorus will not increase dramatically with drastic sediments resuspension.

Key words: Lake Taihu, phosphorus, suspended solids, nutrient release, resuspension flux, windwave disturbance, wave dissipation engineering