太湖藻对水-沉积物界面磷交换过程的影响

采用太湖梅梁湾沉积物和上覆水,以及从太湖水体中分离出的水华优势蓝藻(铜绿微囊藻)和常见绿藻(月芽藻), 室内模拟研究了这2种藻对太湖梅梁湾沉积物磷交换过程的影响. 结果表明:藻种的不同显著影响磷在水-沉积物界面的交换过程. 在沉积物和上覆水灭活条件下,铜绿微囊藻能够显著增加沉积物磷的释放量,引起上覆水中可溶性磷酸盐的增加;而月芽藻的存在没有引起沉积物中磷的明显释放,上覆水中可溶性磷酸盐一直保持在很低水平. 在低磷浓度的水体中,藻类会被诱导产生碱性磷酸酶,分解大分子可溶性有机磷,以满足自身生长的需要. 沉积物中各形态磷存在明显的转化作用,其中铁磷和碱提有机磷含量明显下降,而钙磷和酸提有机磷含量则大幅增加. 

Effects of Algae on the Phosphorus Exchange at Water-Sediment Interface in Taihu Lake

Effect of Microcystis aeruginosa and Selenastram bibrainum Reinsch separated from Taihu Lake on the exchange of phosphorus at the water-sediment interface was studied in laboratory by the use of the sediment and overlying water from Meiliang Bay.The results indicated that the difference of algae species obviously influenced the exchanges of phosphorus at the water-sediment interface.Under sterilized sediment and overlying water conditions,Microcystis aeruginosa evidently improved the release quantity of phosphorus from the sediments,and increased the concentration of dissoluble inorganic phosphate(DIP) in the overlying water.But Selenastram bibrainum Reinsch did not influence the phosphorus release quantity from sterilized sediments,and the concentrations of DIP were kept in a low level during the experiment period.Alga could produce alkaline phosphatase with the low DIP concentration in the overlying water,which could decompose dissoluble organic phosphate(DOP) to DIP and supply enough nutrients to the alga growth.Different phosphorus fractions were transformed obviously in the sediments.Fe bound phosphorus(Fe-P) and alkali extracted organic phosphorus(OrgP_alk) decreased obviously.Ca bound phosphorus(Ca-P) and acid extracted organic phosphorus(Org-P_acd) increased largely.