上覆水环境因子对滨海水库沉积物氮磷释放的影响

Effects of Environmental Factors of Overlying Water on the Release of Nitrogen and Phosphorus from Sediment of Coastal Reservoir

为了解我国滨海水库富营养化过程,以北大港水库沉积物为研究对象,通过室内模拟试验,考察上覆水环境因子〔扰动、ρ(Cl-)、pH、温度、ρ(DO)〕对滨海水库沉积物氮、磷释放的影响.结果表明:1扰动促进氮、磷的释放,ρ(NH_3-N)、ρ(NO_3^--N)、ρ(TN)和ρ(TP)增加了54.4%~230.8%,扰动对滨海水库沉积物TN、TP释放通量的促进作用比淡水沉积物强;2ρ(Cl-)升高促进氮、磷释放,ρ(Cl-)越高,促进效果越强,ρ(Cl-)为1 000和5 000 mg/L时,ρ(NH_3-N)、ρ(NO_3^--N)、ρ(TN)和ρ(TP)分别增加了4.2%、3.2%、35.0%、11.9%和8.4%、4.8%、44.7%、23.8%;3与pH为7.0时相比,pH为8.5和10.0时,ρ(TP)增加了21.3%~42.6%,ρ(NH_3-N)降低了14.9%~18.6%,ρ(NO_3^--N)和ρ(TN)基本没有变化,但NO_3^--N释放通量增加了5.2%~10.3%,TN的释放通量降低了7.1%~21.5%;4温度升高促进了NH_3-N、TN和TP释放,抑制了NO_3^--N释放,滨海水库沉积物中较高的盐度减弱了温度对TP释放的促进作用,25℃时,ρ(NH_3-N)、ρ(TN)和ρ(TP)比5℃时增加了37.3%~71.0%,ρ(NO_3^--N)降低了34.0%;5好氧条件抑制了NH_3-N、TN和TP释放,促进了NO_3^--N释放,好氧条件下ρ(NH_3-N)、ρ(TN)和ρ(TP)降低了54.2%~85.6%,ρ(NO_3^--N)增加了20.5%.研究显示,上覆水环境因子会影响滨海水库沉积物氮、磷释放,其中以扰动、温度和ρ(DO)影响较大.

To investigate the influence of environmental factors（ e. g.,disturbance,chloride ion concentration,pH,temperature and dissolved oxygen） of overlying water on the release of nitrogen and phosphorus from coastal reservoir sediment,laboratory experiments were conducted using sediment samples collected from Beidagang Reservoir. The results were as follows：（ 1） Disturbance of water increased the release of nitrogen and phosphorus. The concentrations of NH3-N,NO3^--N,TN and TP increased ranging from 54. 4% to230. 8%. Besides,disturbance was more effective for the release of TN and TP from coastal sediment than from freshwater sediment.（ 2）The release of nitrogen and phosphorus from sediment increased with increasing Cl-concentrations. The higher the Cl-concentrations were,the more the nitrogen and phosphorus released. At 1000 mg/L Cl-,the concentrations of NH3-N,NO3^--N,TN and TP increased4. 2%,3. 2%,35. 0%,11. 9%. At 5000 mg/L,the values became 8. 4%,4. 8%,44. 7%,23. 8%.（ 3） Compared to the control（ pH =7. 0）, at pH 8. 5 and 10. 0, the concentrations of TP were increased by 21. 3%- 42. 6%, and those of NH3-N were decreased by 14. 9%-18. 6%,while those of NO3^--N and TN had no difference. However,the release rate of NO3^--N was increased by 5. 2%-10. 3%,and that of TN was decreased by7. 1%-21. 5%.（ 4） Higher temperature increased the release ofNH3-N,TN and TP,but decreased that of NO3^--N. The increase of TP release by temperature was inhibited by the higher salinity of coastal sediment. At 25 ℃,the concentrations of NH3-N,TN and TP increased ranging from 37. 3% to 71. 0%,but those of NO3^--N decreased by 34. 0%.（ 5） Under aerobic condition,the release of NH3-N,TN and TP was inhibited,but that of NO3^--N increased; the concentrations of NH3-N,TN and TP decreased ranging from 54. 2%-85. 6% and those of NO3^--N increased by 20. 5%. The results suggested that the release of nitrogen and phosphorus from coastal reservoir sediment is affected by environmental factors especially disturbance,temperature and dissolved oxygen.