2014—2019年焦岗湖水质时空变化与影响因子分析

Temporal and Spatial Variation and Influencing Factors of Jiaogang Lake Water Quality from 2014 to 2019

焦岗湖是淮河流域重要的浅水湖泊和淮河中游最大的生态湿地,基于2014—2019年焦岗湖和2017—2019年入湖河流水质逐月监测数据,利用Mann-Kendall(M-K)趋势检验、主成分分析(PCA)和相关性分析等方法分析焦岗湖水质时空变化规律,探讨入湖河流水质和环境因子对焦岗湖水质和富营养化状态的影响。结果表明:(1)2014—2019年焦岗湖整体属于GB 3838—2002《地表水环境质量标准》Ⅲ~Ⅳ类水之间,富营养状态为中营养和轻度富营养状态之间,主要污染区域在湖区西部和北部。高锰酸盐指数(COD)呈轻微下降趋势;TP和TN浓度年均值处于较高水平,主要原因可能是水产养殖。(2)入湖河流中N、P污染物的外源输入是导致湖区污染物浓度超标的关键因素。(3)主成分分析和相关性分析表明,降水量(P)、温度(T)、溶解氧(DO)和水深(D)对湖区水质有重要影响。降雨增加了外源输入,高温易造成藻类爆发,而水深的增加对水质有所改善。调整养殖产业结构,削减污染物外源输入,是改善焦岗湖水质的关键。

Jiaogang Lake is a significant shallow lake in Huaihe River Basin and the largest ecological wetland in the middle reaches of Huaihe River.Based on the monthly water quality monitoring data of Jiaogang Lake from 2014 to 2019 and four inflow rivers from 2017 to 2019,the spatial and temporal variation of water quality in Jiaogang Lake was analyzed.By using Mann-Kendall trend test,Principal Component Analysis and Correlation Analysis,the effects of inflow rivers and environmental factors on water quality and eutrophication status of Jiaogang Lake are discussed.The results show that:(1)From 2014 to 2019,Jiaogang Lake belongs to the categoryⅢtoⅤof Surface Water Environmental Quality Standard of China(GB 3838-2002).The eutrophication status was between mesotrophic and mild eutrophication.The main contaminated areas were in the northwest and north of the lake area.The concentration of CODshowed a slight downward trend,while the annual average concentrations of TP and TN were relatively stable and at a high level,mainly due to aquaculture.(2)In the lake area,the external input of nitrogen,phosphorus and other pollutants from inflow rivers is the key factorleading to the concentration of pollutants exceeding theⅣstandard of GB 3838-2002.(3)Principal Component Analysis and Correlation Analysis show that precipitation,temperature and depth of lake had great impacts on water quality of the lake area.Rainfall increased exogenous input,high temperature caused algal bloom,but the increase of depth improved the water quality.The key to improve the water quality of Jiaogang Lake is to adjust the structure of aquaculture industry and reduce the external input of pollutants.