2010~2020年太湖无锡水域水质时空变化及原因分析

Water Quality Spatiotemporal Variation and Cause Analysis of Wuxi Water Area of Taihu Lake from 2010 to 2020

分析太湖无锡水域水质时空变化对于区域富营养化控制、水污染防治有重要意义。基于2010~2020年太湖无锡水域逐月水质数据和入湖河流水质数据,采用综合污染指数和综合营养状态指数评估了湖区水质和富营养化状态的时空变化特征,分析了主要水质指标的年际年内变化规律和空间格局,探究了湖区水质与入湖河流污染物浓度及通量的相关性。结果表明,2010~2020年太湖无锡水域水质明显改善,全湖综合污染指数和综合营养状态指数分别下降了25%、10%。除总磷浓度无明显变化趋势外,湖区其余水质因子浓度均呈下降趋势。季节变化方面,高锰酸盐指数、总磷和叶绿素a浓度在夏秋季保持较高值,总氮和氨氮浓度则在冬春季保持较高值。空间上,营养盐浓度由西北部、北部湖区向东南部、东部湖区递减。2013~2020年入湖河流水质变化与湖区水质变化趋势基本一致,其中湖区总氮和氨氮浓度分别与入湖河流总氮浓度和氨氮入湖通量呈显著正相关关系,空间格局响应基本一致,入湖河流的外源输入是影响湖区水质时空变化的重要因素。

The spatial and temporal variations of water quality in Wuxi water area of Taihu Lake are important for regional eutrophication control and water pollution control.Based on the monthly water quality data of Wuxi water area of Taihu Lake and the water quantity data of rivers entering the lake from 2010 to 2020,the spatial and temporal variation characteristics of water quality and eutrophication status of the lake were evaluated using the integrated pollution index and integrated nutrient status index.The inter-annual variation pattern and spatial pattern of major water quality indicators were analyzed,and the correlation between the water quality of the lake and the concentration and flux of pollutants in rivers entering the lake was investigated.The results show that the water quality of Wuxi water area of Taihu Lake improved significantly from 2010 to 2020,and the integrated pollution index and integrated nutrient status index of the whole lake decreased by 25%and 10%,respectively.Except for the concentration of total phosphorus concentration with no obvious change trend,the concentration of other water quality factors in the lake area all showed a downward trend.In terms of seasonal changes,permanganate index,total phosphorus,and chlorophyll-a concentrations maintained higher values in summer and autumn,while total nitrogen and ammonia nitrogen concentrations maintained higher values in winter and spring.Spatially,nutrient concentrations decreased from the northwestern and northern lakes to the southeastern and eastern lakes.The changes in water quality of rivers entering the lake from 2013 to 2020 are basically consistent with the trends of water quality in the lake area.The concentration of total nitrogen and ammonia nitrogen in the lake area are significantly positively correlated with the concentration of total nitrogen in inflow river and the flux of ammonia nitrogen into the lake,respectively.The spatial pattern response is consistent,and the exogenous input of the inflow river is an important factor affecting the spatial and temporal changes of water quality in the lake area.