长江徐六泾近6年水质变化趋势及其响应机制分析

Variation trend of water quality at Xuliujing station of Yangtze River estuary in recent 6 years and its emergency response mechanism

根据徐六泾水质自动站自2013年1月至2018年10月共303周的水质监测数据,分析了5项水质基本指标(水温、pH值、溶解氧、电导率、浊度)和3项重点监测指标(总有机碳、氨氮、高锰酸盐指数)近6 a的变化趋势。对比了溶解氧、高锰酸盐指数和氨氮3项指标2016年1月至2017年10月的人工监测数据,并采用综合水质标识指数法初步探究了自动监测系统对徐六泾断面水质综合变化的预警响应机制。结果表明:徐六泾断面近6 a水环境质量较好,各指标数值波动幅度逐渐减小;两种监测方式对溶解氧和高锰酸盐指数的检测结果相对偏差≤20%的分别占比100%和84.2%,而对氨氮的检测结果相对偏差≤20%的仅占比42.1%。经分析认为主要是由两种方式的检测方法原理不同所引起的系统偏差。但通过单因子水质评价法进行评价时,两种方式的评价结果仍具有较高的一致性;自动监测系统根据响应机制能够直接反馈徐六泾断面水质综合变化情况。徐六泾水质自动监系统不仅为城市供水提供安全保障,更为保护长江口区域生态环境提供科学依据。

According to the water quality monitoring data of Xuliujing Water Quality Automatic Station for 303 weeks from January 2013 to October 2018,the variation trend of five basic water quality indicators(water temperature, pH value, dissolved oxygen, conductivity, turbidity) and three key monitoring indicators(total organic carbon, ammonia nitrogen and permanganate index) in recent six years were analyzed. After comparing with dissolved oxygen, permanganate index and ammonia nitrogen of manual monitoring from January 2016 to October 2017, the emergency response mechanism of the automatic monitoring system to the comprehensive variation of water quality in Xuliujing section was preliminarily explored by using the comprehensive water quality identification index method. The results showed that the water quality of Xuliujing was good and stable in the recent 6 years. The fluctuation of each index was gradually declined. Meanwhile, the ratio of the relative deviation of dissolved oxygen(DO) and permanganate index(CODMn) less than or equal to 20% by two methods is 100% and 84.2%, respectively. But the ratio of the relative deviation of ammonia nitrogen(NH3-N) less than or equal to 20% is only 42.1%. The offset was caused by the system error of two monitoring methods. However, two evaluated results using the single factor water quality assessment method are mostly consistent with each other. According to the emergency response mechanism, the Automatic Monitoring System can directly feedback the comprehensive variations of water quality at Xuliujing station. The Water Quality Automatic Monitoring System of Xuliujing not only provides security for urban water supply, but also provides scientific basis for protecting the ecological environment of the Yangtze River Estuary.