袁河袁州区段溶解氧过饱和成因分析及防治

Cause Analysis of Dissolved Oxygen Supersaturation in Yuanhe River Section of Yuanzhou District

2020年8月15日袁河袁州区段(棚下-袁河水厂取水口)出现溶解氧过饱和现象,为了解该河段溶解氧的变化及提高河道流量前后对水生态环境的影响,将该段河道分为6个监测断面,于8月16—24日监测每个监测点的常规水质、浮游植物群落结构、溶解氧和实时流量。结果表明:自然状态下袁河袁州区段溶解氧沿水流方向从6.8 mg/L逐渐增至12.48 mg/L,出现溶解氧过饱和现象。通过采取流量先大后小的方式持续调水6~10 h,调水期间内河道流量平均提高了40%~47%。增加下泄流量前后袁河袁州区段的总氮、总磷、氨氮和COD_(Mn)差异较小,溶解氧及pH恢复正常水平,但优势浮游植物种类和数量发生显著变化。皮尔逊相关性分析结果表明,溶解氧含量与浮游植物总密度呈显著正相关(P<0.01)。

The phenomenon of dissolved oxygen supersaturation was found in the section of Yuanhe River(from Pengxia to Yuanhe Waterworks intake)on August 15,2020.In order to understand the changes of dissolved oxygen in this section the impact on the water ecological environment before and after increasing the river flow,the river was divided into six sections to monitor routine index include water quality,phytoplankton,dissolved oxygen and real-time flow from 16 to 24 August.The results showed that the dissolved oxygen in this section increased gradually from 6.8 mg/L to 12.48mg/L in the natural state,which showed supersaturation.The river flow increased by an average of 40%-47%during the 6-10 hours of continuous water diversion by adopting the method that the flow was first large and then small.Before and after the increase of discharge,there was little difference in total nitrogen,total phosphorus,ammonia nitrogen and COD_(Mn),dissolved oxygen and pH returned to normal level,but the dominant phytoplankton species and quantity changed significantly.Pearson correlation analysis showed that the dissolved oxygen content was significantly positively correlated with the total density of phytoplankton(P<0.01).