动、静水条件下苦草(Vallisneria natans L.)对沉积物磷释放的影响

The impact of Vallisneria natans L. on the release of phosphorus from sediment under static and hydrodynamic conditions

在浅水湖泊中,沉降在沉积物中的营养盐易受到水流的扰动再释放出来,而沉水植物可以在一定程度减少营养盐的释放.借助自主开发的生态水槽,在40 d的实验周期内检测动、静水条件下有、无苦草（Vallisneria natans L.）时沉积物、上覆水中磷含量变化,旨在为沉水植物对湖泊沉积物营养盐释放量的影响估算及水环境质量评价提供科学依据.结果表明：动水条件下,沉积物在没有苦草的保护下总磷含量下降21.8%,而有苦草的保护下总磷含量下降17.7%.苦草根系从周围沉积物中吸收磷,1~4 cm沉积物层的吸收量高于4~8 cm沉积物层.动水槽的上覆水中总溶解态磷浓度和总颗粒态磷浓度均大量增加,并且总颗粒态磷浓度相对于总溶解态磷浓度占较大比例.苦草减少了沉积物中磷的释放,并对上覆水中正磷酸盐有明显的吸收作用.

In shallow lakes,phosphorus will release from sediments to the overlying water when sediments are disturbed. Submerged plants can reduce the releasing. The impact of Vallisneria natans L. on the release of phosphorus from sediment to water were analyzed in a 40 day lab experiment with the independent hydrodynamic ecological flume under static and hydrodynamic conditions. This study was designed to provide scientific bases for estimating the impact of submerged plants on the release of phosphorus from sediment and the water environmental auality assessment. Results indicated that the phosphorus contents in sediment decreased by 21. 8% under hydrodynamic condition,but decreased by 17. 7% with the protection of V. natans L.. The phosphorus absorbed by V. natans L. in 1-4 cm layer sediment was more than that in 4-8 cm layer sediment. The dissolved phosphorus and the particulate phosphorus dramatically increased in overlying water under hydrodynamic condition and nitrate took a large proportion of total phosphorus in surface water,especially the particulate phosphorus. V. natans L. reduced the releasing of phosphorus from the sediment to the overlying water and large amounts of orthophosphate in the overlying water were absorbed by V. natans L..