苦草(Vallisneria natans)和黑藻(Hydrilla verticillata)对沉积物各形态磷垂直分布的影响

Effects of macrophytes Vallisneria natans and Hydrilla verticillata on the vertical distribution of different phosphorus fractions in sediments

采用沉水植物苦草(V.natans)和黑藻(H.verticillata)作为研究对象,在其旺盛生长期测定群落内外上覆水及沉积物各形态磷的含量,以探究不同根系特点的沉水植物对沉积物中各形态磷垂直分布的影响.结果表明:实验进行30 d后苦草和黑藻组沉积物总磷(TP)、无机磷(IP)和氢氧化钠提取磷(NaOH-P)含量在垂直方向均呈现不同程度的降低.苦草和黑藻组沉积物TP的含量在4.5 cm深度处降低幅度最大,较对照组分别下降了58.91和36.46 mg/kg;IP含量分别在沉积物6.0和3.0 cm深度处降低幅度最大,较对照组分别降低了85.41和57.41 mg/kg.总体来看,沉水植物苦草对沉积物各形态磷含量降低的影响大于黑藻.

In order to study the effects of different root systems in different submerged macrophytes on the vertical distribution of phosphorus fractions in sediments, V. natans and H. verticillata were applied and phosphorus concentrations in overlying water and underneath sediments were investigated during the growth season. Results showed that the contents of total phosphorus （TP）, inor- ganic phosphorus（IP） and NaOH-P fractions in sediments decreased vertically in different levels during both submerged macrophyt- ic groups. Both submerged macrophytic groups reached their maximum decreased values at the depth of 4.5 cm, decreased by 58.91 and 36.46 mg/kg, respectively, comparing with the control. The maximum decreased values of IP in groups of V. natans and 11. verticiUata appeared at the depth of 6.0 and 3.0 cm, and they decreased by 85.41 and 57.41 mg/kg, respectively, compa- ring with the control. The results indicated that the submerged macrophyte V. natans has higher ability in lowering down phosphorus fractions than H. verticiUata in sediments.