常州市典型水生态环境功能区河流水环境质量评价

Water Quality Assessment of Rivers in Aquatic Eco-environmental Function Regions in Changzhou City

为探究常州市辖区内13个河流水生态环境功能区水环境质量状况,于2018年布设57个监测断面开展水质季度监测。应用水质类别、综合水质标识指数法、冗余分析以及主成分分析等方法分析主要水质指标的现状、空间分异特征和季节性变化规律,探究水质状况的主要影响因素。结果表明:①2018年常州市河流水质以GB 3838—2002《地表水环境质量标准》Ⅳ类水为主,水环境质量较差;②主要水质指标浓度时空差异性显著,西部丘陵区水质显著优于东部平原区,夏秋季水质状况优于冬春季;③从水生态环境功能分区来看,东部城镇区域的Ⅲ-09区(生态Ⅲ级区)、Ⅳ-02区(生态Ⅳ级区)、Ⅳ-03区(生态Ⅳ级区)水质较差,而西部Ⅰ-02区(生态Ⅰ级区)、Ⅱ-01区(生态Ⅱ级区)、Ⅲ-08区(生态Ⅲ级区)水质较好.水质状况与水生态环境功能区分级一致性较高,表明水生态环境功能分区可为水质监测、评价、环境管理提供科学参考;④冗余分析结果显示:建设用地是水质恶化的主要影响因素,2000 m以上尺度,耕地相对占比的增加,以及水域面积的减小与水质恶化密切相关;⑤主成分分析结果表明,五日生化需氧量、COD、高锰酸盐指数、总氮具有较高的解释率,表明常州市河流水质主要受有机污染和富营养化的影响。不同等级水生态环境功能区水质状况的威胁因素有差异,生态Ⅳ级区主要受到氨氮和总磷的影响,而生态Ⅲ级区和生态Ⅱ级区主要受到总氮、COD、五日生化需氧量的影响。该研究显示,常州市河流水环境质量较差,其河流水质主要受到有机污染和富营养化污染,存在西部水质优于东部的明显空间差异,与水生态环境功能分区较一致。

In 2018,57 monitoring sections were arranged for a quarterly water quality survey in Changzhou,which can help grasp the water quality of 13 aquatic eco-environmental function regions.The current situation,characteristics of spatial heterogeneity,and seasonal changing laws of main water quality indicators are evaluated by multiple methods such as the water quality grade analysis,comprehensive water quality identification index(WQⅡ)method,redundancy analysis,and principal component analysis.In this way,we can explore the major influencing factors of water quality.The results are as follows:①In 2018,the water quality of rivers in Changzhou City was mainly classified as Grade Ⅳ according to the Environmental Quality Standards for Surface Water(GB 3838—2002),which indicates the poor water quality.②The results show significant spatio-temporal difference in the concentration of main water quality indicators,and the water quality in the western hills is better than that in the eastern plains.The grade of water quality is higher in summer and autumn than in spring and winter.③From the perspective of aquatic eco-environmental function regions,the water quality of Ⅲ-09(ecologically Grade Ⅲ),Ⅳ-02(ecologically Grade Ⅳ),and Ⅳ-03(ecologically Grade Ⅳ)regions in the eastern urban area is poor,while the water quality of Ⅰ-02(ecologically Grade Ⅰ),Ⅱ-01(ecologically Grade II),Ⅲ-08(ecologically Grade Ⅲ)regions in the west is good.The grades of aquatic eco-environmental function regions are highly consistent with the water quality,which proves that the function regions can provide scientific reference for the monitoring,assessment,and environmental management of water quality.④The redundancy analysis shows that the land for construction is the main influencing factor in the deterioration of water quality.The increase in the relative proportion of arable land and the decrease in the aquatic area closely correlate with the deterioration of water quality when the scale is over 2,000 m.⑤The principal component analysis indicates that the five-day biochemical oxygen demand,COD,and permanganate index have high interpretation rates.This shows that the water quality of rivers in Changzhou City is mainly affected by organic pollution and eutrophication.The threat factors of water quality in different grades of aquatic eco-environmental function regions are different.The ecologically Grade Ⅳ area is mainly affected by ammonia nitrogen and total phosphorus,while the ecologically Grade Ⅲ and Grade Ⅱ areas are mainly affected by total nitrogen,COD,and five-day biochemical oxygen demand.The study shows that the water quality of rivers in Changzhou City is poor,and the water quality is mainly influenced by organic pollution and eutrophication.Obvious spatio-temporal difference exists as the water quality in the west is superior to that in the east,which is consistent with the function regions.