底泥不同悬浮方式对水体生物有效磷的影响

Effect of Different Sediment Resuspension Modes on Particulate Phosphorus Bioavailability in Overlying Water

以太湖月亮湾底泥为材料,通过室内模拟实验研究了底泥不同悬浮方式(底泥扰动、底泥曝气)对水体中生物有效磷的影响。结果表明:底泥再悬浮导致颗粒态磷生物有效性呈下降趋势,10 d时,藻类可利用磷(AAP)占总磷(TP)的百分比仅为初始状态(39.86%)时的34.75%(底泥扰动)和17.03%(底泥曝气)。内源磷形态分析表明,悬浮物中Fe/Al-P含量、非闭蓄态Fe/Al-P(AAP)占Fe/Al-P的比重均有下降的趋势。这主要与底泥再悬浮导致溶解氧融入(溶解氧从2.59 mg/L(初始状态)分别增加至5 mg/L(底泥扰动)和6 mg/L(底泥曝气)左右)和pH改变(pH值从8.07(初始状态)分别降至7.4(底泥扰动)和7.3(底泥曝气))有关。实验结束时颗粒态磷生物有效性突然升高,出现这种现象的原因较复杂,可能与底泥再悬浮状态下底泥的物理化学变化和水中微生物的作用有关,还需要进一步探究。底泥再悬浮导致水体中可被利用颗粒态磷(BAPP)和溶解态磷(DTP)含量降低,从而导致上覆水中生物有效磷(BAP)含量降低。

Effect of different sediment resuspensions such as disturbing sediments and aerating to sediments on bioavailable particulate phosphorus（PP） were studied,with sediment taken from Moon Bay in Taihu Lake as materials.Results showed that bioavailability of PP decreased under sediment resuspension conditions.After 10 d,the percentages of algal available phosphorus（AAP） to total phosphorus（TP） in suspended solids were 34.75% for disturbing sediments and 17.03% for aerating to sediments of initial state 39.86% respectively.Sequential fractionation indicated that Fe/Al-P and proportions of non-occluded Fe/Al-P（AAP） to Fe/Al-P decreased gradually under sediment resuspension conditions with time increase,which was attributed to dissolved oxygen（DO） penetration and pH values change.Under sediment resuspension conditions,DO concentrations increased from 2.59 mg/L（initial state） to 5 mg/L（disturbing sediments） and 7.3（aerating to sediments） respectively.Bioavailability of particulate phosphorus is in a sudden increase by the end,and the reasons of the sudden increase in bioavailability of particulate phosphorus by the end are very complex.Maybe it is related to physical and chemical changes in sediment under sediment resuspension and role of microorganisms in water,which need further studies.The concentrations of bioavailable particulate phosphorus（BAPP） and dissolved total phosphorus（DTP） reduce under sediment resuspension conditions.Correspondingly the contents of bioavailable phosphorus（BAP） decrease in overlying water,compared with initial state.