绿潮暴发对滨海湿地沉积物磷释放的影响

Green tides (macroalgal blooms) have occurred frequently in coastal regions in recent years, which seriously affects the ecological environment and nutrient cycle in marine water. According to the fact, the typical coastal wetland and green filamentous algae Cladophora sp. (a prevalent specie of green tieds) are studied with the indoor simulation method combining the field observation and in situ enclosure. The influence of macroalgae growth on phosphorus (P) exchange at sediment-water interface is analyzed in water-sediment-macroalgae system. In addition, some environmental parameters at the interface are investigated during the macroalgae production and decomposition process. The aims of this study are to definite P release mechanism from the sediments and the primary influence factors in three-phase system, and to clarify the influence mechanism of the occurrence and degradation of green tides on sediment P release. The results are helpful to further elucidate the influence mechanism of green filamentous algae on P transference between the sediment and overlying water, which also can provide scientific basis for the control of internal P pollution and the prevention of harmful green tides in coastal wetlands.

针对绿潮（大型绿藻藻华）灾害在近海海域频频暴发，严重影响了生态环境和水体营养盐循环等问题，以典型的滨海湿地和绿潮生物的代表种类刚毛藻（Cladophora sp.）为研究对象，通过室内模拟、野外采样监测与原位围隔相结合的试验方法，在沉积物-水体-海藻体系下研究藻类生长对水体和沉积物中磷迁移转化的影响，检测藻类生长和衰亡时期水土界面微环境的变化，明确三相模式下沉积物磷的释放规律及主控因子，阐明绿潮暴发和消亡对沉积物磷释放的影响程度及其机理。本项目研究将有助于深入阐释大型藻类对水土界面磷迁移转化的影响机制，可为滨海湿地磷内源污染的控制以及绿潮灾害的防治提供科学依据。

本项目以绿潮频繁暴发的荣成天鹅湖湿地为研究对象，研究了藻类生长对水土界面磷迁移转化的影响，明确了藻类分解过程中藻体磷的释放特征，探讨了三相模式下沉积物磷的释放规律及其主控因子，阐释了绿潮暴发和消亡对沉积物磷释放的影响机制。主要成果结论如下：1）在硬毛藻生长过程中，当水体磷含量较高时，藻类具有较高的吸收能力；而磷含量较低时，可诱导碱性磷酸酶活性大幅增加，促进沉积物中磷向上覆水体释放。天鹅湖西北部和湖西端沉积物中磷具有较大的释放潜力和生物可利用性。2）硬毛藻在衰亡分解过程中，累积在藻体内的磷可快速释放，温度是影响藻类分解的首要因素。藻类分解可形成极度的厌氧环境，明显促进了沉积物中可还原态磷的释放。3）藻类分解条件下，扰动对沉积物磷释放的影响最大，厌氧状态次之。在夏季高温且风浪较大的天气，大量硬毛藻的衰败分解可加剧沉积物的内源污染，造成水质严重恶化。