崇明东滩沉积物再悬浮对沉积物-水界面氮、磷交换行为的影响

2002年7月采集崇明东滩低潮滩沉积物样和水样,运用模拟实验研究沉积物再悬浮作用对沉积物-水界面三态氮和可溶磷交换行为的影响实验发现,在沉积物不断发生再悬浮的过程中,水体中三态氮的含量明显增加,其中NO₃^--N变化最为显著,升高浓度值达11.869μmol·L^-1,NH₄⁺-N增长2.1713μmol·L^-1,NO₂^--N的释放约为0.2μmol·L^-1,可溶磷的含量也有少量的增加.同时,再悬浮作用对沉积物-水界面三态氮和可溶磷的环境地球化学行为也有一定的影响,与静置状态相比,NH₄⁺-N和NO₃^--N表现出与静置状态截然相反的变化规律,NO₂^--N受多种因素的影响,变化比较复杂,初期与静置状态相反而后表现一致.再悬浮颗粒物浓度也是制约沉积物-水界面三态氮和可溶磷变化的主要因子之一.实验结果显示,NH₄⁺-N在前7h以内的变化和悬浮颗粒物浓度表现出较好的相关关系,后5h呈负相关关系;NO₂^--N和可溶磷在整个过程中与悬浮颗粒物浓度的变化都有着很好的相关性,只有NO₃^--N的变化与其关系比较薄弱.

Effects of Sediment Resuspension on Nitrogen and Phosphate Exchange at the Sediment-Water Interface in East Chongming Tidal Flat

Sampling sediment and water to mimic sediment resuspension and researching its effects on nitrogen and phosphate exchange at the sediment-water interface in east Chongming tidal flat. Through the experiment, it was found that sediment resuspension causes NO3(-)-N, NH4(+)-N, NO2(-)-N and DIP releases. The release of NO3(-)-N is most marked, the increasing concentration of NO3(-)-N, NH4(+)-N, NO2(-)-N and DIP reach in turns: 11.869 mumol.L-1, 2.1713 mumol.L-1, 0.2 mumol.L-1, 0.02 mumol.L-1. At the same time, resuspension also change nitrogen and phosphate exchange at the sediment-water interface compare to without resuspension to great extent. NH4(+)-N and NO3(-)-N have absolutely opposite diversification with and without resuspension; NO2(-)-N shows complicated transformation because of many effected elements. The result of the experiment display the changes of NH4(+)-N, NO2(-)-N and DIP concentration in water have good relation to SPM (mg.L-1), this relation have not appear in change of NO3(-)-N.