沉水植物生长期对沉积物和上覆水之间磷迁移的影响

分别在春季培养黑藻(Hydrilla verticillata)和苦草(Vallisneria natans),在冬季培养菹草(Potamogeton crispus),跟踪监测在沉水植物影响下环境因子的变化,及上覆水和沉积物各形态磷的浓度变化,以探讨沉水植物对磷在沉积物和上覆水中迁移转化的规律.结果表明,不同季节实验条件下沉水植物均能不同程度降低上覆水中各形态磷的浓度.在植物生长期上覆水磷浓度保持在相对较低的水平,黑藻、苦草和菹草组上覆水中总磷(TP)的浓度分别保持在0.03～0.05、0.04～0.12和0.02～0.11 mg.L-1.沉水植物组沉积物中各形态磷的浓度均呈现不同程度的降低,黑藻、苦草和菹草组沉积物TP的含量最大降低幅度分别为35.34、60.67和25.92 mg.kg-1.植物组上覆水溶解氧(DO)、氧化还原电位(Eh)和pH均显著提高(DO 10.0～14.0mg.L-1;Eh 185～240 mV;pH 8.0～11.0),沉积物中Eh(-140～-23 mV)也明显提高,并使得沉积中pH保持在中性范围内(7.2～8.0).沉水植物通过提高上覆水中的DO、Eh和pH及沉积物Eh的方式影响上覆水和沉积物之间磷的迁移转化.

Influence of Submerged Macrophytes on Phosphorus Transference Between Sediment and Overlying Water in the Growth Period

In order to study the process of phosphorus transfer between sediment and overlying water, Hydrilla verticillata and Vallisneria natans were cultured in spring, Potamogeton crispus was cultured in winter. Changes of environmental factors and phosphorus concentrations in water and sediment were investigated. The results indicated that: submerged macrophytes could reduce all phosphorus fractions in the overlying water. Phosphorus concentrations in overlying water maintained in a relative low level in the growth period of submerged macrophytes. The concentrations of total phosphorus (TP) in overlying water of H.verticillata, V. natans and P. crispus were 0.03-0.05,0.04-0.12,0.02-0.11 mg·L^-1, respectively. All phosphorus fractions in sediment were reduced. The maximum value between submerged macrophyte and control of H.verticillata, V. natans and P. crispus were 35.34, 60.67 and 25.92 mg·kg^-1, respectively.Dissolved oxygen (DO), redox potential (Eh) and pH in overlying water increased (DO 10.0-14.0 mg·L^-1, Eh 185-240 mV, pH 8.0-11.0) in the submerged macrophytes groups. Submerged macrophytes increased Eh(-140--23 mV) and maintained pH(7.2-8.0) in neutral range. The results indicated that submerged macrophytes affected phosphorus transferring between sediment and overlying water through increasing DO,Eh and pH in overlying water, and Eh in sediment.