刚毛藻分解对荣成天鹅湖沉积物磷释放的影响

在荣成天鹅湖刚毛藻暴发和非暴发区域分别采集沉积物进行室内加藻模拟试验,定期监测上覆水的溶解氧（DO）、pH、化学需氧量（COD）和可溶性磷（SRP）等指标的变化,并分析了刚毛藻分解对沉积物磷释放的影响。结果表明,避光培养过程中,刚毛藻分解使上覆水体的DO含量大幅降低,形成厌氧环境（0~0.14 mg.L-1）;COD含量则明显增加,各处理最大值变化在0.59~6.93 mg.L-1之间。刚毛藻分解可明显促进沉积物中磷的释放,培养期间上覆水SRP的含量大幅上升,变幅为0.01~1.51 mg.L-1;暴发区沉积物＋10 g藻和沉积物＋30 g藻处理的最大释磷量分别为沉积物处理的2.06倍和1.91倍。不同湖区沉积物磷的释放能力存在较大差异,暴发区沉积物的释磷量明显高于非暴发区,沉积物释放是前者上覆水磷含量增加的主要来源,而在非暴发区藻类分解释放的磷高于沉积物中释放的磷。

Influence of Decomposition of Cladophora on Phosphorus Release from the Sediments of Rongcheng Swan Lake,China

Rongcheng Swan Lake is a coastal lagoon in eastern Shandong Peninsula,China,whose water quality has deteriorated in recent years and large amounts of Entermorpha prolifera occur in the spring and summer.In present study,the sediments were sampled in dominated zone and non-dominated zone of Cladophora in the lake,and cultivated with algae in the laboratory to reveal the influence of algal decomposition on P release from the sediments.Concentrations of dissolved oxygen（DO）,chemical oxygen demand（COD）,soluble reactive phosphorus（SRP）and pH in the overlying water were monitored during the experiment.Due to the decomposition of Cladophora,DO concentration in overlying water declined significantly and reached the anoxic condition（0~0.14 mg·L-1）.However,COD concentrations of different treatments increased greatly,and the maximum varied from 0.59 mg·L-1 to 6.93 mg·L-1.During the algal decomposition,SRP concentrations in overlying water increased significantly,ranging from 0.01 mg·L-1 to 1.51 mg·L-1.The maximum release amount of sediments with algae was much higher than that of sediments without algae.In dominated zone,P release amounts of sediments with algae treatments were almost twice of treatment without algae.P release ability from the sediments differed among different areas,which was significantly higher in the dominated zone than that in non-dominated zone.In dominated zone,the released P from sediments constituted the most part of P in overlying water;while in non-dominated zone,the released P from algal decomposition were higher than that from the sediments.In a word,the decomposition of Cladophora had an obvious effect on the P level of lake water.