藻类生长对沉积物上磷迁移转化的影响

Effect of Algae Growth on Phosphorus Migration and Transformation on Sediments

通过模拟中肋骨条藻(Skeletonema costatum)和沉积物共存体系,探究了富营养化条件下,藻类与沉积物对无机磷的吸收/吸附作用的相互影响。采用自制的金汞伏安微电极测定了藻与沉积物共存体系中溶解氧(DO)的含量变化,分析了体系中溶解氧含量变化与磷消耗速率以及沉积物中磷形态分布变化之间的关系。结果表明,在本课题研究范围内,共存的藻类与沉积物互相影响彼此对磷的消耗过程,1.0×10^4、5.0×10^4和1.0×10^5 cells/mL三种初始藻密度的中肋骨条藻(Skeletonema costatum)48 h后对磷的吸收百分比分别达54.7%、73.4%、93.8%,添加沉积物后分别降至21.3%、34.1%和51.9%;沉积物对培养基介质中的无机磷的吸附百分比为42.5%,加入三种不同藻密度的藻体后分别降至9.1%、2.8%及0.3%。高密度藻与沉积物共存体系的耗磷速率与体系DO含量呈显著负相关(p<0.05)。体系中DO浓度降低会促进沉积物中Fe-P向水体中释放,从而导致沉积物中铁结合态磷(Fe-P)含量的降低。可交换态磷(Ex-P)、有机磷(OP)和Fe-P是藻类存在时沉积物向水体中较易释放的形态。

The interaction between skeletonema costatum and sediment on the absorption/adsorption of inorganic phosphorus under eutrophication was investigated in this paper.In-situ measurement of dissolved oxygen(DO)in the system of skeletonema costatum and sediment was carried out by Au/Hg voltammetric microelectrode.The relationship between DO concentration and the rate of phosphorus consumption,as well as the migration of different phosphorus fractions were preliminary discussed.The results showed that algae and sediments interacted with each other to consume phosphorus in coexistence system under the research conditions of this study.The absorption percentages of phosphorus by skeletonema costatum with the initial cellular concentrations of 1.0×10^4,5.0×10^4 and 1.0×10^5 cells/mL after 48h were 54.7%,73.4%,and 93.8%,respectively,which decreased to 21.3%,34.1%and 51.9%after adding sediment.The percentage of phosphorus adsorbed by sediments in the medium was 42.5%,which respectively decreased to 9.1%,2.8%and 0.3%after adding skeletonema costatum with the three initial cellular concentrations as above.There was a significant negative correlation(p<0.05)between the phosphorus consumption rate and the concentration of DO only in the case of high cellular concentration.The decline of DO concentration promoted the release of Fe-P into the overlying water,thus resulting in a decrease in the content of Fe-P in sediment.In addition,Ex-P,OP and Fe-P were the forms which sediment preferentially released into overlying water in the presence of skeletonema costatum.