贵州红枫湖底泥磷释放的模拟实验研究

A Simulation Study on the Release of Phosphorus from Sediments in Lake Hongfeng,Guizhou Province,China

在实验室条件下,模拟了温度、溶解氧（Dissolved Oxygen,DO）、pH、扰动、微生物等环境因子对红枫湖底泥磷释放的影响。实验结果表明：（1）底泥磷的释放量随温度的升高而增大,5℃时底泥磷的释放通量为0.59mg·m-2·d-1;25℃和35℃时底泥磷的释放通量分别为1.25和3.68mg·m-2·d-1。（2）厌氧（DO〈2.0mg/L）条件下,底泥磷释放显著,释放通量在1.15~4.57mg·m-2·d-1之间;好氧（DO〉6.0mg/L）条件下,底泥磷的释放通量仅为0.82mg·m-2·d-1。（3）底泥磷的释放与上覆水pH值密切相关,且释放量随上覆水pH值的升高而增大,当pH=5.5和pH=7.5时,底泥磷的释放通量分别为1.15和1.25mg·m-2·d-1;当pH=9.5时,底泥磷的释放通量为4.57mg·m-2·d-1。（4）扰动条件下的底泥磷释放通量（2.62mg·m-2·d-1）明显大于静置条件下的底泥磷释放通量（1.25mg·m-2·d-1）。（5）微生物对底泥磷释放有明显影响,灭菌条件下的底泥磷释放量明显大于有微生物条件下的底泥磷释放量。综上所述,高温、厌氧、高pH值、强烈扰动均可促进红枫湖底泥磷的释放,微生物对底泥磷释放有明显抑制作用。基于红枫湖底泥磷释放模拟实验结果,计算了不同环境条件下红枫湖底泥磷的释放通量,在此基础上估算出红枫湖夏季热分层期间（6~9月）底泥磷释放量约为8.58t,占红枫湖水体总磷负荷（约28t）的30.6%,表明红枫湖底泥内源磷释放对水体磷负荷和富营养化有重要贡献,亟待开展底泥内源污染治理。

A simulation study on the release of phosphorus from sediments in Lake Hongfeng,Guizhou Province,China was conducted by controlling temperature,dissolved oxygen（DO）,pH,disturbance and microbial activities.Our results show that：（1）the amount of sedimentary phosphorus release increases with rising temperature.When T= 5℃,the flux of sedimentary phosphorus release is 0.59mg·m-2·d-1.When T=25℃and T=35℃,the flux of sedimentary phosphorus release is 1.25 and 3.68mg·m-2·d-1,respectively;（2）Under anaerobic condition（DO2.0mg/L）,the sediment obviously releases phosphorus to the overlying water;the flux of sedimentary phosphorus release is 1.15-4.57mg·m-2·d-1.Under aerobic condition（DO6.0mg/L）,the flux of sedimentary phosphorus release is only 0.82mg·m-2·d-1;（3）The release of sedimentary phosphorus is closely related to pH of the overlying water and the amount of sedimentary phosphorus increase with rising pH.When pH=5.5and pH=7.5,the flux of sedimentary phosphorus release is 1.15 and 1.25mg·m-2·d-1,respectively.When pH=9.5,the flux of sedimentary phosphorus release is 4.57mg·m-2·d-1;（4）Under disturbed condition,the flux of sedimentary phosphorus release（2.62mg·m-2·d-1）is higher than the undisturbed one（1.25mg·m-2·d-1）;and（5）Microbes influence the release of sedimentary phosphorus to the overlying water significantly.Under sterilized condition,the amount of sedimentary phosphorus release is larger than the microbial influence.In summary,high temperature,anaerobic condition,high pH,and intense disturbance could stimulate release of sedimentary phosphorus.Notably,microbes significantly inhibites sedimentary phosphorus release to the overlying water.Based on results of the laboratory simulation study,the fluxes of sedimentary phosphorus release under different environmental conditions were calculated and the estimated amount of sedimentary phosphorus release during summer thermal stratification（6-9 months）was 8.58 t,accounting for30.6% of total phosphorus load of the water body（about 28t）and indicating that the release of sedimentary phosphorus make an important contribution to phosphorus load and eutrophication of the water body.It is therefore urgent to manage the polluted sediment in Lake Hongfeng.