不同水深条件下狐尾藻生长对沉积物氮磷的影响

Influence of Myriophyllum spicatum's growth on nitrogen and phosphorus in sediment in different water depth

采用巢湖原位试验研究了80、160和240 cm 3个水深条件下生长的沉水植物狐尾藻(Myriophyllum spicatum L.)对沉积物和间隙水中氮磷的影响。结果表明,狐尾藻的株高和生物量随着水深的增加总体呈下降趋势,并且其差异随着生长期的延长而加大,水深为240 cm的条件下狐尾藻具有最小的株高和生物量,即240 cm的大水深条件不利于狐尾藻的个体形态构建;而相对浅的水深条件(80和160 cm)则是其生长的较佳生境。狐尾藻的生长过程中能够通过根系吸收和根际环境的改变使沉积物和间隙水中的氮磷含量明显下降,一定程度上降低了沉积物氮磷向上覆水体释放的风险,并且其抑制能力随着不同水深条件下植株的长势不同而有所差异,即在植株生长良好的浅水条件下其对沉积物和间隙水中氮磷的抑制效果更佳。因此,较浅的水环境有利于沉水植物的生长,同时还能充分发挥植物对沉积物氮磷的控释作用。

In-situ experiments were carried out in Chaohu lake to investigate the influence of water depth on Myriophyllum spicatum L as well as that on nitrogen and phosphorus characteristics in sediment and interstitial water.The results showed that plant height and biomass of the studied plant decreased with increasing water depth on the whole,namely,the characteristics of plant height and biomass are much better in water depth of 80 cm and 160 cm than that of 240 cm.Meanwhile,the nitrogen and phosphorus levels of sediment and interstitial water decreased obviously during the growth of M.spicatum because of the root absorption and the change of root zone environment.This function can reduce the risk of nitrogen and phosphorus releasing from sediment to overlying water,which plays an important role in protecting lakes from eutrophication.And this function is associated with plant growth condition,plant can inhibit nitrogen and phosphorus releasing more effectively with better growth condition and vice versa.In conclusion,shallow water is favorable for the growth of M.spicatum,and makes full use of the functions in reducing nitrogen and phosphorus in sediment and interstitial water.