太湖贡湖湾(望虞河以西)主要河口区域水质状况评价

Assessment of water quality in the estuarine area (west of Wangyu River) of Gonghu Bay,Taihu Lake,China

为探讨贡湖湾(望虞河以西)河口区域的水质状况,采用WQI(水质综合指数)在夏季(2017年8月)和冬季(2018年3月)对其8个河口区域的31个点位进行了水质状况评价,并计算WQImin(最小水质综合指数),识别主要水质因子。WQI将水质状况分成5个等级进行评价,即WQI>90为非常好,70<WQI≤90为好,50<WQI≤70为中等,25≤WQI≤50为差,WQI<25为非常差。研究表明:①研究区域的水质状况具有显著的季节性差异,夏季的水质状况总体评价为中等(WQI为54.62),冬季总体评价为好(WQI为73.63);②河口之间的水质状况具有区域性差异,夏季闸门内外水质状况差异明显,河道的水质状况优于湖泊,小溪港河口区域水质状况相对最差(WQI为47.50),冬季壬子港河口区域的WQI最小,为62.84;③总磷(TP)、总氮(TN)、溶解氧(DO)和高锰酸盐指数(CODMn)等4个水质指标是影响研究区域水质状况的关键性因子。研究显示:贡湖湾(望虞河以西)河口区域的水质状况具有明显的时空差异,WQI的分级评价和关键因子识别能为研究区域的水环境治理提供参考依据,并有助于为相关管理部门对同类河口的水生态修复提供决策思路。

The study assessed the actual water situation in the estuarine area of Gonghu Bay(west of Wangyu River),Lake Taihu,China,based on the status of water quality using WQI(water quality index)methods,and the WQI min(minimum water quality index)was also calculated to identify the main water quality factors.In the summer(August 2017)and winter(March 2018)seasons,8 estuarine areas were tested at 31 sampling sites,which included lakes and rivers.The WQI was divided water quality into five grades,WQI>90 was very good,70<WQI≤90 was good,50<WQI≤70 was medium,25≤WQI≤50 was bad and WQI<25 was very bad.The results indicated that the water quality had significant difference on season in the study area,the overall water quality status of summer were medium(WQI:54.62),and in winter,the overall status were good(WQI:73.63).Differences were also observed between the estuarine areas of Gonghu Bay.In summer,the water quality between the two sides of sluices in some estuaries were obviously different,the status of river-side were better than that of lake-side,and the estuarine area of Xiaoxi River had relatively worse water quality status(WQI:47.50).In winter,Renzi Gang had the minimum WQI,which was 62.84.TP,TN,DO and COD Mn used in the WQI min were the most effective parameters in our study.According to the study,the water situation in the estuarine area of Gonghu Bay(west of Wangyu River)had obvious spatio-temporal differences,and the grading evaluation of WQI and the identification of key factors can provide a valuable contribution to inform decision-making for the management of water environments by providing the actual water situation of the estuarine area of Gonghu Bay and other similar estuaries.