Spatial and seasonal variations of water quality in the upstream plain river networks of the Taihu Basin

Abstract

在太湖流域上游的宜溧洮滆水系主要河道设置67个监测点，分别于2014年1月（冬季）、4月（春季）、8月（夏季）、11月（秋季）进行水质监测，采用多元统计方法分析了水质的空间差异性和季节性变化，并利用水质标识指数法对水环境质量进行评价.结果表明，宜溧洮滆水系污染程度较严重，总氮（TN）、总磷（TP）和高锰酸盐指数（COD_Mn）浓度年均值分别为4.93、0.26和7.63 mg/L；单因素多元方差分析和聚类分析显示污染物浓度具有显著时空差异性，时间上冬、春季污染程度较高而夏、秋季较低，空间上无锡和常州氮、磷污染较为严重，宜兴和溧阳市有机污染程度较高；水质标识评价结果显示流域内水质基本为IV类或V类，其中TN、TP及COD_Mn是关键污染指标.;Sixty-seven water sampling sites in the Yili-Taoge plain river networks of the upstream area of the Taihu Basin were set to characterize its water quality with spatiotemporal distribution. Water sampling trips were conducted in January (winter), April (spring), August (summer), November (autumn) of 2014, and main water quality parameters were concentrated on nutrients and organic matters. Spatial and seasonal variations of water quality were analyzed by using the multivariate statistical methods and water quality were assessed by employing the comprehensive water quality identification index. The results indicated that pollution degree in the research area was severe. The averaged concentrations of total nitrogen (TN), total phosphorus (TP) and permanganate index (COD_Mn) were 4.93 mg/L, 0.26 mg/L and 7.63 mg/L, respectively. One-way multivariate analysis and cluster analysis showed significantly spatiotemporal patterns of pollutants. Pollution levels in winter and spring were higher than that in summer and autumn. Pollution of nitrogen and phosphorus were heavier in the Wuxi and Changzhou areas, whereas organic matter pollution was more serious in the Yixing and Liyang areas. Water quality in the upstream plain river networks can meet the criteria of Grade IV or V of National Standards for Surface Water Quality, characterized by pollution of TN, TP and COD_Mn.