沉水植物黑藻对上覆水中各形态磷浓度的影响

Effect of submerged plant Hydrilla verticillata on the concentrations of different phosphorus species in overlying water

室内模拟研究了沉水植物黑藻对上覆水中不同形态磷浓度的影响及其季节性变化,并从沉水植物生长、间隙水和碱性磷酸酶活性(APA)三方面进行了讨论,进一步揭示磷在浅水湖泊水-沉积物界面的交换机理。结果表明,在本研究条件下,上覆水中各形态磷以溶解性总磷(DTP)为主,其他形态磷浓度变异较大,黑藻降低了上覆水中总磷(TP)、溶解性活性磷(SRP)和DTP浓度,也降低了DTP和SRP占总磷的比例,从而使颗粒态总磷(PP)和溶解性有机磷(DOP)占总磷比例升高。黑藻主要通过吸收上覆水中的磷和抑止沉积物、上覆水中APA使上覆水中各形态磷浓度保持较低水平,其中对SRP和DTP浓度的影响更明显。上覆水中各形态磷浓度呈现明显的季节性变化。在7～8月,TP、SRP和DTP浓度呈下降趋势,并在8月达到最低值;9～10月间有所升高,但仍然维持在较低水平,不同采样时间存在波动。

The effect of a submerged plant Hydrilla verticillata on the concentrations of different phosphorus species in overlying water and its seasonal variation were investigated under simulating condition, and were also discussed from three aspects of the growth of submerged plant Hydrilla verticillata, the effect of pore water and the alkaline phosphatase activity （APA）. The mechanism of the phosphorus exchange at sediment-water interface in shallow lake was elucidated ulteriorly. The results indicate that in this paper the main phosphorus specie in overlying water was dissolved total phosphorus （DTP）, and the concentrations of other phosphorus species change greatly. Hydrilla verticillata reduced the concentrations of total phosphorus （TP）, soluble reactive phosphorus （SRP） and DTP overlying water, and also reduced the percentages of DTP and SRP to TP and increased the percentages particulate phosphorus （PP） and dissolved organic phosphorus （DOP） to TP. The submerged plant Hydrilla verticillata can reduce the concentrations of different phosphorus species, especially SRP and DTP, in overlying water mainly by uptaking the phosphorus from overlying water and inactivating the APA of the sediment and the overlying water. The concentrations of different phosphorus species in overlying water change seasonally. The concentrations of TP, SRP and DTP decrease from July to August and attain the lowest in August; and increase a little, maintained low levels and also fluctuate at different sampling time during September and October.