【摘要】 为了解西江干流水体高锰酸盐指数(COD_Mn)的时空特征及影响因素,分别于2017年9月、12月和2018年3月、6月对西江红水河大湾至肇庆江段进行了季节调查,并对其水环境质量进行了初步分析与评价。结果表明:该水域COD_Mn质量浓度变化范围为0.73～4.83 mg/L,均值为2.67 mg/L;季节均值呈6月（3.08 mg/L）>12月（3.03 mg/L）>9月（2.94 mg/L）>3月（1.62 mg/L）的变化特征;依据COD_Mn水平, 13个样点可聚为3个类群, COD_Mn数值上呈聚群Ⅲ>聚群Ⅰ>聚群Ⅱ情况;水体COD_Mn污染指数（Pi）范围在0.18～1.21之间,处于"无污染–轻污染"状况,不同月份COD_Mn超标率为12月>6月>9月> 3月;水质标识指数评价结果得到西江干流大部分时期水质类别为Ⅰ～Ⅱ类,少数时期为Ⅲ类,其中3月水质最好,都为Ⅰ类, 9月、12月为Ⅱ类, 6月为Ⅱ～Ⅲ类;统计分析结果显示COD_Mn与水温（WT）、TP呈显著正相关,与盐度（Sal）、DO、透明度（SD）、NO3-N、NO2-N、叶绿素a （Chl a）和N/P比值呈显著负相关,并受到TP和PO4-P和DO的显著性影响。西江干流水体污染目前尚不严重,水质优于中国境内其他主要河流;分析认为河流水动力情势及周边人类活动干扰是决定水体COD_Mn含量高低的重要因素;水体还原性有机质与TP具有一定的同源性,来自区域点源。更多还原

【Abstract】 To understand the dynamic patterns of the permanganate index(COD_Mn) and impact factors in the surface water of the mainstream of Xijiang River, seasonal investigations were conducted between Dawan of Hongshui River and Zhaoqing of Xijiang River from September 2017 to June 2018. The water quality was analyzed and evaluated basing on the present study. During the investigation, the COD_Mn concentration varied in the range of 0.73～4.83 mg/L, and the mean value was 2.67 mg/L. The seasonal COD_Mn mean value were 3.08 mg/L（June）, 3.03 mg/L（December）, 2.94 mg/L（September）, and 1.62 mg/L（March）. The 13 sample stations were clustered in three groups, and the highest content of COD_Mn was found in cluster Ш, followed by cluster Ⅰ, with the lowest in cluster Ⅱ. Results of pollution conditions based on COD_Mn were in the range of 0.18～1.21, whereas the corresponding water quality levels were "no pollution" to "light pollution." The temporal water pollution for the annual average content of COD_Mn in water from the 13 sites in descending order was December, June, September, and March. The water quality identification index and levels based on COD_Mn showed that at most times in one year the water quality classification belonged to class Ⅰ or Ⅱ, and the last times belonged to class Ⅲ. Specifically, water quality in March was best with assigned to class Ⅰ, followed by periods in September and December, which was belonged to class Ⅱ, and the worst water quality was in June, which belonged to class Ⅱ to Ⅲ. Correlation analysis with other physical and chemical factors showed that COD_Mn had a significant positive correlation with water temperature and total phos phorus, and it was significantly negatively correlated with salinity, dissolved oxygen（DO）, secchi depth, total phosphorus, nitrate nitrogen, nitrite nitrogen chlorophyll a, and N:P. Stepwise regression analysis showed that COD_Mn concentration was significantly affected by total phosphorus, phosphate, and DO. According to the present study, it was determined that the water environment in mainstream of Xijiang River was lightly polluted and the water quality was better than most of the other rivers in our country. It was also concluded that the hydrodynamic situation of the river and human settlements near the sampling area were the factors affecting the COD_Mn concentration. Additionally, it was determined that the reducibility of organic matter came from "point source pollution" in the investigation area, which was in common with the sources of water total phosphorus mass.更多还原