基于长时间序列乌梁素海水环境变化趋势及生态补水等关键驱动因子分析(2011-2020年)

Water environment change trend and ecological water replenishment of Lake Wuliangsuhai and other key driving factors analysis based on long time series(2011-2020)

基于2011—2020年乌梁素海水质监测数据,将综合营养指数法、PCA排序法和ArcGIS克里金插值法有机结合,综合评价2011—2020年乌梁素海水体富营养化程度年际时空变化特征,厘清引起水体富营养化发生变化的关键性驱动因子。研究结果表明:(1)乌梁素海水体总磷和总氮的峰值出现在平水期,氨氮的峰值在枯水期,COD_(Mn)的峰值在丰水期,水质整体以地表Ⅲ类水为主。(2)2011—2020年湖体水质经历了由轻度富营养-中营养-轻度富营养-中营养的变化过程,综合营养状态指数在60~70(中度富营养)的湖区面积占比由21.49%逐渐消失,综合营养状态指数在30~50(中营养)的湖区面积占比由23.84%扩增到44.87%。(3)乌梁素海生态补水量与总氮、总磷、COD_(Mn)和综合营养状态指数呈负相关,是影响湖泊水体营养化的另一个关键性驱动因子。

Based on the water quality monitoring data of Lake Wuliangsuhai from^(2)011 to 2020,the comprehensive nutrition index method,PCA sorting method and ArcGIS Kriging interpolation method were combined to comprehensively evaluate the interannual temporal and spatial variation characteristics of the eutrophication degree of Lake Wuliangsuhai from^(2)011 to 2020.Additionally,this study aimed to elucidate the key drivers that contributed to changes in water eutrophication.The research results showed that:(1)The peaks of TP and TN of Lake Wuliangsuhai occurred during the flat water period,the peak of NH 3-N was observed during the dry season,and the peak of COD_(Mn)was during the wet season.The overall water quality was found to be mainly surface water.(2)Between 2011 and 2020,the water quality of the lake underwent a transition from mild eutrophication to moderate eutrophication,followed by a retum to mild eutrophication,and ultimately to a state of medium nutrient status.The proportion of the lake area with a comprehensive nutrient index of 60-70(moderate eutrophication)decreased from^(2)1.49%to a point where it has now nearly disappeared,while the proportion of the lake area with a comprehensive nutritional index of 30-50(medium nutrition)increased from^(2)3.84%to 44.87%.(3)The ecological water replenishment of Lake Wuliangsuhai was negatively correlated with TN,TP,COD_(Mn)and comprehensive nutrient status index,This indicates that ecological water replenishment was another key driver that impacted the trophication of lake water.