铜绿微囊藻污染下滇池草海表层沉积物中各形态磷的含量

Contents of Different Forms of Phosphorus in Surface Sediments of Caohai of Dianchi Lake under Microcystis aeruginosa Pollution

通过设置3种浓度的铜绿微囊藻(Microcystis aeruginosa)污染的模拟实验,研究滇池草海表层(0~20 cm深度)沉积物中各形态磷含量的变化规律。研究结果表明,在低、中和高浓度铜绿微囊藻污染下,表层沉积物中的平均全磷质量比分别为1 245.61 mg/kg、1 241.04 mg/kg和1 230.80 mg/kg;在中浓度铜绿微囊藻污染下,表层沉积物中的有机磷和钙结合态磷质量比分别由实验开始时的560.05 mg/kg和558.39 mg/kg降至实验结束时的420.96mg/kg和510.98 mg/kg,铁结合态磷和铝结合态磷质量比分别由实验开始时的66.07 mg/kg和175.24 mg/kg增至实验结束时的86.21 mg/kg和188.06 mg/kg,说明铜绿微囊藻浓度增大会促进表层沉积物中内源磷的释放。在中、高浓度铜绿微囊藻污染下,表层沉积物中的全磷含量分别与钙结合态磷含量和有机磷含量显著正相关,钙结合态磷和有机磷是表层沉积物中全磷内源负荷的主要磷形态。在高浓度铜绿微囊藻污染下,叶绿素a含量与铝结合态磷含量显著相关,铝结合态磷是对叶绿素a含量增加贡献最大的磷形态。控制表层沉积物内源磷中钙结合态磷和有机磷的释放,降低铜绿微囊藻对沉积物铝结合态磷的吸收,是减少蓝藻暴发的有效途径。

In this study, the change laws of different forms of phosphorus contents in surface sediments of Caohai was studied by setting up simulation experiment under different concentrations of Microcystis aeruginosa. The results showed that the average value of total phosphorus contents in surface sediments were 1 245.61 mg/kg,1 241.04 mg/kg and 1 230.80 mg/kg under Microcystis aeruginosa pollution of low, medium and high concentrations. Under the condition of medium concentration of Microcystis aeruginosa, the contents of organic phosphorus and calcium-bound phosphorus decreased from the initial values of 560.05 mg/kg and 558.39 mg/kg to420.96 mg/kg and 510.98 mg/kg in the end, respectively, while the contents of ferrum-bonded phosphorus and aluminum-bonded phosphorus increased from the initial values of 66.07 mg/kg and 175.24 mg/kg to 86.21 mg/kg and 188.06 mg/kg in the end, respectively. The results explained that the increased concentration of Microcystis aeruginosa could promote the release of endogenous phosphorus in sediments. Under medium and high concentration of Microcystis aeruginosa, there was a significantly positive correlation between total phosphorus content and calcium bound phosphorus content and organic phosphorus content. Calcium-bound phosphorus and organic phosphorus were the main phosphorus forms of total phosphorus load in surface sediments.Chlorophyll-a content was positively correlated with aluminum bound phosphorus contents under high concentration of Microcystis aeruginosa, and aluminum bound phosphorus was the most important phosphorus form contributing to chlorophyll-a growth. Therefore, controlling the release of calcium-bound phosphorus and organic phosphorus in surface sediments and reducing the absorption of aluminum-bound phosphorus by Microcystis aeruginosa in parallel is an effective way to reduce the bloom of Cyanobacteria.