溶氧·水温和水流对东太湖沉积物中氮·磷释放的影响

Effect on the Release of Nitrogen and Phosphorus from Sediment of the East Taihu by Dissolved Oxygen,Water Temperature and Currents

[目的]研究东太湖底泥内源污染强度。[方法]通过室内模拟试验,分析环境因子(溶解氧、水温、水流)对东太湖底泥中N、P释放的影响。[结果]在不同溶解氧(DO)和水温条件下,上覆水中N、P浓度都随时间呈线性升高。DO浓度为3.0、5.5、8.0 mg/L时,N的平均释放速率分别为443、239、153 mg/(m2×d),P的平均释放速率分别为33.2、17.8、12.1 mg/(m2×Day);水温为15、25、35℃时,N的平均释放速率分别为81、169、301 mg/(m2×Day),P的平均释放速率分别为8.7、15.8、19.3 mg/(m2×Day);不同水流速度下,上覆水中的N、P浓度先呈线性升高,120h后趋于平衡;水流速度为0.02、0.04、0.08 m/s时,96 h内N的平均释放速率分别为45、78、161mg/(m2×Day),P的平均释放速率分别为1.8、7.5、16.8 mg/(m2×Day)。[结论]沉积物中N、P释放速率随着溶解氧降低、水温升高和水流加快而提高,其中溶解氧的影响最大。

[Objective] The aim was to research the endogenous pollution intensity of the East Taihu Lake.[Method] The effects were analysed on the release of nitrogen and phosphorus from sediment of the east Taihu for the environmental factors,such as dissolved oxygen,water temperature and the flow by laboratory simulation experiments.[Result] The results showed that the nitrogen,phosphorus concentrations of the overlying water were increased linearly with time in different dissolved oxygen（DO） and water temperature conditions.When dissolved oxygen in the concentration of 3.0,5.5,8.0 mg/L,the average release rate of nitrogen accordingly reached 443,239,153 mg/（m2×day）,the average release rate of phosphorus reached 33.2,17.8,12.1 mg/（m2×day）.When the water temperature were in 15,25,35 ℃,the average release rate of nitrogen respectively reached 81、169、301 mg/（m2×day）,the average release rate of phosphorus reached 8.7、15.8、19.3 mg/（m2×day）;When the flow rate was different,nitrogen,phosphorus concentrations of the overlying water would increase linearly with time and tended to be in balance after 120 hours;When the water flow at the rate of 0.02,0.04,0.08 m/s,the average release rate of nitrogen were 45,78,161 mg/（m2×day） in 96 hours,the average release rate of phosphorus were 1.8,7.5,16.8 mg/（m2×day） in 96 hours.[Conclusion]The Nitrogen,phosphorus release rates from the sediment increased with the dissolved oxygen reducing,water temperature and flow increasing and the effect of the dissolved oxygen was the greatest.