不同类型沉积物磷形态转化及其对狐尾藻生长的影响

在室内模拟条件下利用不同类型沉积物培养穗状狐尾藻,分析了沉积物与上覆水各形态磷的变化,以及狐尾藻生物量和根系形态的差异,揭示不同沉积物中各形态磷的转化特性及其对沉水植物生长的影响.结果表明,在研究条件下,外加细沙改变了沉积物的颗粒度,促进沉积物中磷的释放,增加了上覆水磷浓度;外加氮源,改变沉积物的化学性状,抑制沉积物中磷的释放,降低了上覆水中磷的浓度;添加细沙使狐尾藻植株及根系干重增加了49%和107%,根长增加了19%;而外加氮源对植株根系生长产生了抑制作用,使狐尾藻早衰;狐尾藻生长促进了沉积物中磷的释放,其衰退增加了沉积物中磷的沉积,各形态磷随着狐尾藻的生长呈先降后升趋势,其中以Fe/Al-P变化量最大(41%～57%);根系长度是影响狐尾藻对沉积物中磷吸收和释放的主要形态指标,根直径主要通过影响沉积物的通透性间接促进沉积物中磷的释放.

Effect of Different Type Sediments on Transformation of Phosphorus Forms and Growth of Myriophyllum spicatum

The changes of the different phosphorus (P) forms in sediments, overlying water and the diversity of dry weight and root forms of Myriophyllum spicatum were studied using different type sediments under simulating condition. The characteristic of transformation of P forms and growth of submerged plant Myriophyllum spicatum were illustrated. The results indicated that the P release was promoted by adding the silver sand in sediment, and their P concentrations in the overlying water were increased. The chemical characteristic of the sediments were changed by adding NH₄Cl, which restrained the P release from their sediments and decreased the P concentration in their overlying water. About 49%, 107% of their plant, root dry weight and 19% root length ofMyriophyllum spicatum from different treatments were raised by adding silver sand in sediments. The root growths of the Myriophyllum spicatum from different treatments were restrained and their agings were promoted by adding NH₄Cl in sediments. The P release from sediments were accelerated by the growth ofMyriophyllum spicatum,and the early decay of Myriophyllum spicatumcan increase the P accumulation in sediment. The changing trend of different P forms in the sediments decreased firstly, and then increased with the Myriophyllum spicatum growthing, their contents of Fe/Al-P form in sediments varied greatly (41%-57%). The P release and adsorption in sediments were mainly affected by their root length index of Myriophyllum spicatum from different treatments. The P release in sediment was accelerated through their changing penetrate capacity by root diameter increasing.