蓝藻消亡分解过程中的水质变化及营养盐释放特征

Changes of Water Quality and Characteristics of Nutrients Release During the Algal Extinction

为研究蓝藻消亡分解对湖泊水质及水体营养盐的影响,从巢湖藻类水华易发区收集新鲜藻浆,在室内进行了蓝藻消亡分解实验,探讨蓝藻消亡分解过程中的水体溶解氧(DO)、总氮(TN)、总磷(TP)等理化指标的变化。研究结果表明,在蓝藻消亡分解过程中,水体DO和氧化还原电位(ORP)会在短时间内迅速下降,最低值分别达0.1 mg/L和-200 mV,使水体处于厌氧强还原状态;蓝藻中的营养盐会快速向水体中释放,导致水体氮磷浓度持续升高,使水体TN、氨氮(NH_(3)-N)、TP最大浓度分别达到初始浓度的2.15、1.18、2.60倍。在蓝藻消亡分解过程中,水体营养盐浓度与藻类生物量呈显著负相关。对蓝藻聚集区内的蓝藻开展快速有效打捞,对于遏制蓝藻污染十分必要。

The experiments of algal extinction and decomposition were conducted to indicate the effects of algal extinction and decomposition on the water quality of lakes and nutrients in water using fresh algae suspension collected in the pron algal bloom area of Chaohu Lake.Meanwhile,the changes of the physical and chemical indicators of water quality including dissolved oxygen(DO),oxidation reduction potential(ORP),electrical conductivity(EC),total nitrogen(TN),total phosphorus(TP),and ammonia nitrogen(NH_(3)-N)were explored simultaneously.The results indicated that the process of cyanobacteria dying out and decomposing led to a rapid decline of DO and ORP in a short period of time,and minimum value dropped to 0.1 mg/L and-200 mV,so that the water body was at an anaerobic and strong reduction state.The algae decomposition process accelerated the release of nutrients into the water body,resulting in the continuous increase of nitrogen and phosphorus nutrient concentrations.The maximum concentrations of TN,NH3-N and TP were 2.15,1.18 and 2.60 times of that of the initial water.In addition,significant negative correlation between the concentrations of nutrients and cyanobacteria biomass in the process of cyanobacteria dying out and decomposing revealed that quickly salvaging cyanobacteria in bloom area is indispensable and effectively to hold back further expansion of cyanobacterial blooms.