长江上游沱江流域地表水环境质量时空变化特征

Characteristics on Spatiotemporal Variations of Surface Water EnvironmentalQuality in Tuojiang River in Upper Reaches of Yangtze River Basin

沱江是长江流域上游最重要的支流之一,为了明晰沱江流域水质时空变化特征和防治重点,根据2010—2017年沱江流域36个监测断面水质监测数据,采用单因子评价法和秩相关系数法,从年份、月份、季度和水期4个时间段进行了分析.结果表明:沱江流域水质状况总体上污染较重,但有向好趋势,总磷(TP)为首要污染物,流域断面达标率呈先上升后下降复上升的趋势;水质指标浓度年内变化显著,水质指标浓度丰水期达到最小值,枯水期达到最大值;沱江干流监测断面水质类别好于支流;TP和氨氮(NH3-N)浓度空间变异性较弱,化学需氧量(COD)和生化需氧量(BOD5)浓度则存在较强空间变异性.虽然沱江流域水质有变好趋势,但沱江流域面临的污染问题依然严峻,今后要高度重视污染源治理,尤其是TP的防治工作.

Tuojiang River is one of the most important tributaries among the Upper Reaches of Yangtze River basin. In order to characterize of the water quality variations and the prevention focus of Tuojiang River basin,this paper presents analyses in its four periods of the year,month,quarter and water period using single factor evaluation and rank correlation coefficient method, based on the monitoring data of water quality in 36 monitoring sections in Tuojiang River Basin from 2010 to 2017, the results show that the water quality of Tuojiang River basin was generally in a polluted state, but has a positive trend. Total phosphorus(TP) was the primary pollutant. The standard rate of water quality monitoring sections in basin shows a trend of increasing first, then decreasing and then increasing again. The water quality index changed significantly during the year, which reached its minimum in wet season and reached the maximum in dry season. Besides, the water quality of the main stream was better than that of the tributary. The spatial variability of TP and ammonia nitrogen(NH3-N) concentrations were weak, and the spatial variability of chemical oxygen demand(COD) and biochemical oxygen demand(BOD5) concentrations were strong. Although the water environmental quality of Tuojiang River basin has changed, the pollution problem that Tuojiang River basin faced is still grim. Therefore, it is necessary to attach great importance to the control of pollution source, especially the prevention of TP in future.